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WO1993001606A1 - Commutateur commande par ecoulement de fluide - Google Patents

Commutateur commande par ecoulement de fluide Download PDF

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Publication number
WO1993001606A1
WO1993001606A1 PCT/AU1992/000321 AU9200321W WO9301606A1 WO 1993001606 A1 WO1993001606 A1 WO 1993001606A1 AU 9200321 W AU9200321 W AU 9200321W WO 9301606 A1 WO9301606 A1 WO 9301606A1
Authority
WO
WIPO (PCT)
Prior art keywords
fluid flow
flow switch
switch
paddle
switch according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AU1992/000321
Other languages
English (en)
Inventor
Kerry James Field
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO1993001606A1 publication Critical patent/WO1993001606A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/40—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by devices allowing continual flow of fluid, e.g. vane
    • H01H35/405—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by devices allowing continual flow of fluid, e.g. vane the switch being of the reed switch type

Definitions

  • This invention relates to improvements in fluid flow sensing switches. More particularly, the invention relates to a fluid flow switch comprising an actuating paddle arm which is corrosion resistant and operable by a magnet or magnets encased in the paddle arm acting in conjunction with a switch.
  • Switches for switching on and off electrical circuits, and remotely controlling electrical equipment, when fluid either flows, or ceases to flow in a pipe or conduit, or open channel, are collectively known as flow switches.
  • These switches according to the prior art usually comprise a housing, a switch assembly and a paddle of sheet metal or plastic positioned so fluid flow impinges on the paddle face and causes it to deflect.
  • a switch which may be mechanically or magnetically actuated is controlled by the deflection of the paddle, and thus a switch output is obtained.
  • the paddle deflection which is responsive to fluid flow usually occurs against a spring bias, or counter weight, so that when flow ceases the paddle returns to its undeflected state or state of natural repose under the action of the spring bias or weight.
  • a spring bias or counter weight
  • an external method of pre-loading the spring is employed. This usually consists of an adjusting screw with suitable sealing, positioned to compress the pre-load spring. Where corrosive or aggresive fluids are to be sensed, conventional paddle flow switches tend to be unsuitable, due to corrosion of the metal components and potential leakage of fluids through spring seals, bellows or adjusting screws.
  • One example of a prior art flow switch involves the use of magnets attached to the top end of a paddle arm such that the magnet actuates a reed switch.
  • the types of magnets which has been used comprised aluminium, nickle and cobalt.
  • the prior art flow switches have adopted the use of a metal bellows to which the top end of the paddle arm is attached. The bellows rocks when the arm is moved and trips a micro switch included in a flow switch housing.
  • a sensitivity adjustment is provided in this type of flow switch by means of a spring loaded screw in the housing which retards the rocking of the bellows and provides a sensitivity adjustment.
  • One problem that exists with the bellows type flow switches is that the sensitivity of the switch is directly related to the mechanical strength of the bellows.
  • the sensitivity of the switch decreases thereby reducing its efficiency and effectiveness. If the bellows is made from very thin metal the switch can have a high degree of sensitivity but a very low pressure rating. On the other hand, if the bellows is strong, the switch is less sensitive but has a high pressure rating. As an example of this the typical switch may be rated at 10 bars but will be irreversibly damaged by fluid pressures over 20 bars.
  • the prior art switches have generally been made of metal, for instance, the flow switch may have a bronze body and stainless steel paddle arm.
  • the flow switches have also adopted conventional micro switches or reed switches.
  • the present invention seeks to overcome the prior art disadvantages by providing a flow switch wherein the paddle arm is made of a plastics material and carries within the paddle a magnet isolated from contact with the fluid in which the paddle is located.
  • This type of switch avoids the disadvantages associated with corrosion of mechanical components and resultant insensitivity.
  • the present invention provides finer control of the switching threshold compared to the spring bias switches, zero friction associated with the adjusting mechanism across the entire adjustment range, elimination of spring fatigue or corrosion and an elimination of change in switch sensitivity over the life of the switch as well as a higher pressure rating.
  • the present invention comprises; a corrosion resistant fluid flow switch for insertion in a fluid flow channel or line, said flow switch comprising; a housing, at least one switch assembly connected to a power source and located therein, a paddle arm electrically and mechanically isolated from the switch and pivotally attached within or to said housing thereby forming two free ends, one of said ends engaging with the fluid in which the fluid flow switch is inserted; and at the other end at least one magnet embedded in the paddle arm which, in conjunction with at least one other opposing biasing magnet located within or on the housing, biases the paddle towards a natural repose position wherein the switch assembly is either open or closed according to the predetermined configuration of the switch assembly and the paddle arm; wherein, when fluid flows in one direction resisting the bias, the switch assembly adopts either an open or closed condition commensurate with said predetermined configuration and when fluid flow in that direction stops or flows in the opposite direction, the paddle arm returns to its position of natural repose thereby closing or opening the switch assembly.
  • the invention comprises: a corrosion resistant fluid flow switch for insertion in a fluid flow channel or line; said flow switch comprising; a housing, at least one switch assembly located within the housing and connected between a power source and an appliance, a paddle arm electrically and mechanically isolated from the switch and pivotally attached within or to said housing thereby forming two free ends with one of said ends engaging with the fluid in which the fluid flow switch is inserted and at the other end at least one magnet embedded in the paddle arm which, in conjunction with first and second biasing magnets, the first located on the housing and the second magnet spaced apart from the first magnet and located on a biased switching arm bias the paddle towards a natural repose position wherein the switch assembly is either open or closed according to the predetermined configuration of the switch assembly and paddle arm; wherein, when fluid flows in one direction resisting the bias, the switch assembly adopts either an open or closed condition commensurate with said predetermined configuration and when fluid flow in that direction stops or flows in the opposite direction, the paddle arm returns to its position of natural repose thereby closing or opening
  • the fluid flow switch comprises in the housing one or more biasing magnets which is/are adjustable relative to the magnet or magnets in the paddle arm so as to alter switch sensitivity according to requirements.
  • the housing is substantially T shaped with the outstanding leg of the T comprising a hollow cavity into which the paddle arm locates.
  • the paddle arm has an integral pivot which locates in recesses in the housing from within the housing cavity.
  • the magnets used in the paddle arm and housing may comprise Neodymium, Iron, Boron increasing magnetic power to simulate spring strength operation.
  • the paddle arm is electrically and mechanically isolated from the flow switch, and also from the biasing magnet. This prevents fluid within which the fluid flow switch is located coming in contact with any metallic part which could be susceptacle to corrosion.
  • Figure 1 presents a long sectional view of the flow switch according to a preferred embodiment of the invention.
  • Figure 2 represents a side elevational view of the flow switch according to the embodiment of figure 1.
  • Figure 3 represents a sectioned side elevation of the flow switch of the embodiment of figure 1.
  • Figure 4 represents a partly disassembled version of the preferred embodiment of figure 1 showing the bearing screw released.
  • Figure 5 shows an alternative embodiment of the invention.
  • Flow switch 1 comprises a body 2 which is preferrably injection molded from a chemically inert thermo plastic material such as polypropolene.
  • Housing 2 is formed substantially in the shape of a T comprising two principle sections, a main housing 3 and a connecting leg 4.
  • Connecting leg 4 comprises a cavity 5 within which paddle arm 6 fits.
  • the paddle arm comprises a substantially elongated member having one end adapted to engage with the fluid in which the fluid flow switch is to be used and the other end comprising at least one magnet.
  • End 8 of the paddle arm 6 comprises a substantially planar paddle member 9 which presents a face to the direction of fluid flow and which enables the paddle arm to pivot about bearing pin 10.
  • bearing pin 10 is molded as an integral part of the paddle arm 6.
  • the paddle arm is injection molded from a suitable chemically resistant and resilient thermo plastic such as polycarbonate.
  • the bearing pin 10 is held in position by means of eccentric bearing screw 11.
  • the bearing screw 11 is screwed into connecting leg 4 of the body 1.
  • Bearing screw 11 is sealed by an 0-ring 12 which nests in a recess (not shown) in the body of the connecting leg 4.
  • Bearing pin 10 locates in recess 13 in connecting leg 4.
  • Magnet 7 of paddle arm 6 is embedded in the material of the paddle such that it is totally covered by the plastics material. Thus, there is no metallic contact between air and/or fluid in which the flow switch is placed.
  • Magnets may be cylindrical or a planar disc as shown or alternatively, they may be a number of different shapes and comprise Neodymium, Iron and Boron. As an alternative to molding in of the magnet it is possible to insert the magnet/s in the body of the paddle and then place a cover over the magnet opening.
  • Housing 3 comprises therein a circuit board assembly 14 with screw means 15 anchoring the circuit board to the base 16 of the housing 3.
  • FIG. 1 Associated with the circuitry is a reed switch 17 which is outstanding from the circuit board so that it presents in the direction of the magnetised upper end of the paddle arm.
  • Figure 2 shows an external side view of the flow switch depicted in figure 1.
  • Connecting leg 4 is adapted with threaded shank 18 to facilitate connection with a fluid flow pipe not shown.
  • Connecting leg 4 also has a part 19 which is threaded internally and forms a blind bore which terminates in the body of the connecting leg 4 before it would otherwise enters cavity 5.
  • an adjusting screw 20 which is fitted with a magnet 21 at the extremity of shank 22.
  • Magnet 21 is orientated so that its pole face matches the pole face of magnet 7 which is molded into the paddle arm 6.
  • the polarity of the respective magnets 21 and 7 are such that magnet 21 tends to repel magnet 7 away from it such that the natural repose position of the paddle arm 6 is rotated away from magnet 21 to the limits of its travel by the interaction of the two magnets.
  • a natural repose position of the paddle arm 6 can be as shown in figure 3.
  • the paddle arm 6 can be preloaded away or preloaded toward the adjusting magnet 21 by effecting an appropriate adjustment to the polarity.
  • the screw 22 is provided with a screw driver slot 23 so as to enable the adjustable biasing of magnet 21 and movement thereof inward or outward relative to the position of magnet 7 in the paddle arm 6 in order to increase or decrease the magnetic preload on the paddle arm 6 .
  • This adjustment capability provides a range of sensitivities for the reed switch 17.
  • the use of this methodology achieves what the mechanical action achieved in the prior art devices effected by an adjustable spring sensitivity mechanism but with an elimination of the disadvantages of the spring and without any mechanical intrusion into the wet cavity of the flow switch.
  • the flow switch may be produced in which there are no metal components exposed to the fluid being sensed. This represents an advantage over the conventional metal or metal/plastic flow switches.
  • the flow switch 1 described uses a magnetically coupled reed switch 17 to achieve an electric output.
  • Magnet 7 in the paddle arm 6 has sufficient pole strength to actuate reed switch 17.
  • the reed switch 17 may be used directly as the electrical output device or it may be used to gate into conduction a solid state switch such as a triac, to control a relay.
  • the housing 3 is sealed against connecting leg 4 by means of sealing rings 24.
  • Housing 3 houses the circuit board 14 which acts as the reed switch 17 and also a cable termination block 25. Cable termination block 25 enables connection of an electrical appliance to the switch which is to be actuated according to the operation of the flow switch depending upon how it is set relative to fluid flow.
  • a heat sink 26 is optionally included in the housing to support a triac 27.
  • Housing 3 is positioned by means of screws 15. Beneath the heads of the screws 15 are 0 ring seals 28.
  • a cable gland 29 is shown screwed to the housing 3. When the housing 3 is constructed and anchored in this way, the electrics inside are rendered waterproof and electrically safe.
  • the flow switch body 1 is connected by a threaded portion 18 into a T in a pipe line.
  • Paddle arm 6 would normally be cut or profiled so that when the flow switch was installed in the pipe system, the paddle 9 protrudes into the flow stream but does not contact any part of the pipe including the pipe walls.
  • an operator Prior to setting of the flow switch into position in a fluid flow line an operator first must decide on the directional polarity of the magnets so as to decide on the repose position of the paddle arm 6. Which ever biasing arrangement is decided, that is, whether the magnets are repelling or attracting, the flow switch is inserted such that the fluid flow in order to actuate the paddle arm 6 passes in a direction which tends to resist the biasing forces exerted by the magnets.
  • magnets 21 and 7 are repelled such that the natural repose position of the paddle arm 6 is such that the magnets are at maximum separation.
  • the tendancy is for the magnets 21 and 7 to be forced towards each other against the action of the repulsive bias.
  • the repulsion between the magnets 21 and 7 causes the paddle arm 6 to again be pushed away and out of proximity of the reed switch 17 thereby causing the reed switch to revert to the off condition.
  • the magnets 21 and 7 may be arranged to attract or repeal each other depending on the orientation of the magnetic poles and the nature of the switch requirements according to the fluid flow required.
  • the position shape and numbers of magnets may be varied in the paddle arm and housing.
  • the effective action of the magnets simulates the mechanical action of the prior art devices by simulating a biasing effect.
  • the adjusting biasing magnet 21 may be replaced by a piece of ferrous material such as iron and provided magnet 7 has sufficient strength, it will be attracted to the metal. The net effect of this is an arrangement which performs the same function as that achieved in the use of a tension spring arrangement.
  • the electrical function of the flow switch may be reversed to provide an on condition when there is no flow acting against the paddle arm 6 and an off condition when flow impinges on the arm 6.
  • This reverse function is achieved by turning the entire electrical board assembly around and due to the reed switch 17 being positioned out of centre with respect to the paddle arm 6 and out of center of opposite hand effect is achieved which reverses the output of the switch.
  • FIG 4 there is shown a sectional view of a flow switch according to the preferred embodiment of figure 1 this time showing bearing pin 11 released.
  • Paddle arm 6 is displaced sideways to a point where the bearing pin 11 on the side of the paddle arm has disengaged from bearing hole 30. In this position the paddle arm may be removed without withdrawing it axially.
  • a trench 31 is provided within the body of connecting leg 4 to allow the off side bearing boss to clear the body cavity and thus be withdrawn or reassembled.
  • the paddle arm depicted in figures 1 to 4 is intended for use in applications which require the flow switch to be fitted into pipes in which liquids may be flowing. It is nevertheless possible for the flow switch to be utilised for indicating flow conditions of other fluids such as gases. Furthermore, it is practical to employ the flow switch to monitor liquid flow in open channels to detect flows of vapours.
  • FIG 5 there is shown a flow switch according to an alternative embodiment wherein there are three magnets used.
  • Figure 5 depicts a flow switch actuated by a paddle arm 32, as previously described, to which a micro switch 33 is fitted.
  • the micro switch 33 is fixed to a backing plate 34 which is held in position against the flow switch body 35 by the two fixing studs 36.
  • the micro switch 33 is provided with an arm 37, of preferably non ferrous material, such as brass or stainless steel.
  • the arm 37 is free to pivot about a bearing pin 38.
  • a magnet 39 is suitably fixed. This magnet is oriented so its face pole repels against the paddle magnet 40, when the paddle arm 32 is in close proximity thereto.
  • a small compression spring 41 is provided to balance the weight of the arm 37 and magnet 39, and to act as a mechanical dampener to unwanted movement of the arm 37.
  • the repulsive force developed between the magnets 40 and 39 when in close proximity is sufficient to cause the arm 37 to be lifted, depressing the micro switch button 43.
  • This action causes the micro switch to change electrical state. That is, a closed circuit may be obtained between the micro switch electrical terminals, 44 normally open, and 45 common. An open circuit is obtained between terminals 45 common, and 46 normally closed.
  • micro switches which are arranged to operate two circuits simultaneously.
  • pneumatic pilot valves may be actuated by the flow switch.
  • Magnetic repulsion may be utilised, in a like manner to the method previously described for electrical switches.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Indicating Or Recording The Presence, Absence, Or Direction Of Movement (AREA)
  • Measuring Volume Flow (AREA)

Abstract

Commutateur commandé par écoulement de fluide, résistant à la corrosion et destiné à être incorporé dans un canal ou une canalisation dans lesquels s'écoule un fluide. Ledit commutateur comprend un boîtier avec à l'intérieur au moins un ensemble commutateur connecté à une source de courant, un bras à palette (6) isolé électriquement et mécaniquement du commutateur et fixé de manière pivotante dans ou sur ledit boîtier (2), formant ainsi deux extrémités libres, une de ces extrémités étant en contact avec le fluide passant dans la canalisation dans laquelle le commutateur est au moins un aimant (7) noyé dans le bras à palette; cet aimant, conjointement avec au moins un autre aimant de sollicitation (21) monté en opposition de polarisation et situé dans ou sur le boîtier, sollicite le bras à palette (6), selon la polarité des aimants, vers une position naturelle de repos dans laquelle l'ensemble commutateur est soit ouvert soit fermé selon une configuration prédéterminée de l'ensemble commutateur et du bras à palette, et dans laquelle, lorsque le fluide s'écoule dans une direction résistant à la sollicitation, l'ensemble commutateur adopte soit un état ouvert, soit un état fermé correspondant à la configuration prédéterminée, et lorsque l'écoulement de fluide dans cette direction s'arrête ou se poursuit dans la direction opposée, le bras à palette (6) reprend sa position de repos naturel, fermant ou ouvrant ainsi l'ensemble commutateur.
PCT/AU1992/000321 1991-07-05 1992-06-30 Commutateur commande par ecoulement de fluide Ceased WO1993001606A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPK7050 1991-07-05
AUPK705091 1991-07-05

Publications (1)

Publication Number Publication Date
WO1993001606A1 true WO1993001606A1 (fr) 1993-01-21

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PCT/AU1992/000321 Ceased WO1993001606A1 (fr) 1991-07-05 1992-06-30 Commutateur commande par ecoulement de fluide

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7105756B1 (en) 2005-09-21 2006-09-12 Plastic Magen, Lp Flowswitch having reduced number of parts
WO2009019732A1 (fr) * 2007-08-07 2009-02-12 Comem S.P.A Agencement d'ajustement d'écoulement pour un relais de buchholz
CN103453946A (zh) * 2013-08-19 2013-12-18 佛山市高明毅力温控器有限公司 用于液体循环管道的流量检测器
CN103617924A (zh) * 2013-10-29 2014-03-05 大连葆光节能空调设备厂 流体磁性信号器
FR3006761A1 (fr) * 2013-06-06 2014-12-12 Jpc Sas Detecteur de debit pour conduite de circulation de liquide

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB707408A (en) * 1951-05-18 1954-04-14 Trist & Co Ltd Ronald Improvements relating to magnetic transmissions
DE2632673A1 (de) * 1976-07-16 1978-01-19 Laaser & Co Nachf Kontrollgeraet fuer stroemung, druck und temperatur
US4081635A (en) * 1976-03-19 1978-03-28 Delaval Turbine Inc. Electrical switch responsive to a predetermined fluid flow
US4143255A (en) * 1977-09-19 1979-03-06 Jack Herscovitz Device for detecting fluid flow
DE2744901A1 (de) * 1977-10-06 1979-04-19 Hammelrath Turbo Werk Fritz Waechter fuer den durchfluss oder den fuellstand von medien

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB707408A (en) * 1951-05-18 1954-04-14 Trist & Co Ltd Ronald Improvements relating to magnetic transmissions
US4081635A (en) * 1976-03-19 1978-03-28 Delaval Turbine Inc. Electrical switch responsive to a predetermined fluid flow
DE2632673A1 (de) * 1976-07-16 1978-01-19 Laaser & Co Nachf Kontrollgeraet fuer stroemung, druck und temperatur
US4143255A (en) * 1977-09-19 1979-03-06 Jack Herscovitz Device for detecting fluid flow
DE2744901A1 (de) * 1977-10-06 1979-04-19 Hammelrath Turbo Werk Fritz Waechter fuer den durchfluss oder den fuellstand von medien

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7105756B1 (en) 2005-09-21 2006-09-12 Plastic Magen, Lp Flowswitch having reduced number of parts
WO2009019732A1 (fr) * 2007-08-07 2009-02-12 Comem S.P.A Agencement d'ajustement d'écoulement pour un relais de buchholz
RU2468461C2 (ru) * 2007-08-07 2012-11-27 Комем С.П.А Газовое реле для защиты силового электрического оборудования с масляной изоляцией
FR3006761A1 (fr) * 2013-06-06 2014-12-12 Jpc Sas Detecteur de debit pour conduite de circulation de liquide
CN103453946A (zh) * 2013-08-19 2013-12-18 佛山市高明毅力温控器有限公司 用于液体循环管道的流量检测器
CN103453946B (zh) * 2013-08-19 2016-06-29 佛山市高明毅力温控器有限公司 用于液体循环管道的流量检测器
CN103617924A (zh) * 2013-10-29 2014-03-05 大连葆光节能空调设备厂 流体磁性信号器

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