Claims:WE CLAIM:

1. A gas flow measuring device (10), comprising:
- a housing (12) with a gas inlet opening (12I) and a gas outlet opening
(12O);
- a U-shaped tube (14) having an inlet leg (14I) and an outlet leg (14O)
disposed inside the housing (12), such that the gas enters vertically
downwards form the gas inlet opening (12I) into the inlet leg (14I) and
flows vertically upwards from the outlet leg (14O) through the gas outlet
opening (12O);
- a fixed member (16) mounted in the outlet leg (14O), such that the
fixed member (16) allows flow of the gas through it;
- a floating member (18) disposed in the outlet leg (14O) in the path of
the gas, such that the floating member (18) is held floating vertically
above the fixed member (16) and moves vertically due to the gas flow;
- a magnetic field detecting sensor (20) located outside the outlet leg
(14O), such that the sensor (20) detects a change in magnetic field due
to vertical movement of the floating member (18); and
- an electronic system (22) to convert a magnetic field value into flow
rate of the gas.

2. The gas flow measuring device (10) according to claim 1, wherein the outlet leg (14O) includes a diverging portion (14D), a straight portion (14S) and a converging portion (14C), such that the diameter of the diverging portion (14D) increases along upwards from a diameter of the outlet leg (14O) to a diameter of the straight portion (14S) and decreases along upwards from the diameter of the straight portion (14S) to the diameter of the outlet leg (14O) in the converging portion (14C).

3. The gas flow measuring device (10) according to claim 2, wherein the fixed member (16) is mounted in the outlet leg (14O) below the diverging portion (14D) and the floating member (18) is disposed in the diverging portion (14D).

4. The gas flow measuring device (10) according to claim 3, wherein the diameter of the floating member (18) is more than the diameter of the outlet leg (14O), such that the floating member (18) is held in the diverging portion (14D) without contacting the fixed member (16).

5. The gas flow measuring device (10) according to claim 1, wherein the floating member (18) is held floating by balancing its downward weight and a magnetic force created by a magnetic field.

6. The gas flow measuring device (10) according to claim 1, wherein the floating member (18) moves vertically when there is change in the gas flow rate and acquires a fixed position on reaching equilibrium.

7. The gas flow measuring device (10) according to claim 1, wherein the floating member (18) is in a form of at least one of a ball, a disc, a ring or a combination thereof.

8. The gas flow measuring device (10) according to claim 1, wherein each of the floating member (18) and the fixed member (16) are made of a magnet.

9. The gas flow measuring device (10) according to claim 1, wherein the fixed member (16) is made of magnet and the floating member (18) is made of a ferromagnetic material.

10. The gas flow measuring device (10) according to claim 1, wherein the floating member (18) is made of magnet and the fixed member (16) is made of a ferromagnetic material.

11. The gas flow measuring device (10) according to claim 1, wherein the magnetic field detecting sensor is a hall effect sensor.

12. The gas flow measuring device (10) according to claim 1, wherein the fixed member (16) is in a form of a circular ring.

13. The gas flow measuring device (10) according to claim 1, wherein the electronic system is calibrated to report gas flow rate as per the magnetic field value.

14. A method (100) of measuring a gas flow rate, the method comprising the steps of:
- guiding (110) the gas to pass through a U-shaped tube (14) having an inlet leg (14I) and an outlet leg (14O) disposed inside a housing (12), such that the gas enters vertically downwards into the inlet leg (14I) and flows vertically upwards from the outlet leg (14O);
- mounting (120) a fixed member (16) in the outlet leg (14O), the fixed member (16) is adapted to allow flowing of the gas through it;
- disposing (130) a floating member (18) in the outlet leg (14O) in the path of the gas, such that the floating member (18) is held floating vertically above the fixed member (16) and moves vertically due to the gas flow;
- detecting (140) a change in a magnetic field due to vertical movement of the floating element (18); and
- converting (150) the magnetic field value into gas flow rate.

15. The method (100) of measuring a gas flow rate according to claim 15, wherein the floating member (18) is held floating by balancing its downward weight and a magnetic force created by a magnetic field.

16. The method (100) of measuring a gas flow rate according to claim 15, wherein the magnetic field is created by one of the fixed member (16) and the floating member (18).
, Description:FIELD OF THE INVENTION

[001] The present invention relates generally to mass flow measuring devices and methods, and more particularly to gas flow measuring devices and method.

BACKGROUND OF THE INVENTION

[002] A gas meter is a specialized flow meter, used to measure the amount of gases delivered through a pipeline. The gases may be fuel gases such as natural gas and liquefied petroleum gas. Gas meters are used at residential, commercial, and industrial buildings that consume fuel gas supplied by a gas utility.

[003] The flow rate of gas is measured using a range of gas meters which are based on different methods of measuring the gas flow rate. Some of the major types of gas meters includes diaphragm meters, rotary displacement meters, turbine meters, Ultrasonic flow meter and Coriolis meters. The Diaphragm Meter has four measurement chambers linked together to form a unit that is separated by a diaphragm and deformable wall. These diaphragms are connected to each other via a rotating piston. The quantity of gas passing through the diaphragm meter can be directly measured if the volume of each chamber is already known. Diaphragm meters can also be employed with pulse generators for providing a meter reading.

[004] In Rotary Displacement Meters, two rotating impellers are placed within a housing and rotate opposite to each other make up the full body of the rotary displacement meter. The impellers are positioned such that their cross-sections are perpendicular to the rotating axis, and the gap between the impellers and housing is very small. The quantity of gas can be directly measured as the volume of each chamber is well known.

[005] Turbine Meters use a gearwheel system, a turbine wheel, an extrusion section and a sealed housing as main components of the Turbine meter. At the time of gas flow, the turbine wheel starts rotating. The rotation of the turbine wheel is proportional to the flow velocity. Therefore, the volume of gas can be measured with respect to the rotation of the wheel.

[006] An ultrasonic flow meter is a type of flow meter that measures the velocity of a fluid with ultrasound to calculate volume flow. Using ultrasonic transducers, the flow meter can measure the average velocity along the path of an emitted beam of ultrasound, by averaging the difference in measured transit time between the pulses of ultrasound propagating into and against the direction of the flow or by measuring the frequency shift from the Doppler effect.

[007] Coriolis flow meters artificially introduce a Coriolis acceleration into the flowing stream and measure mass flow by detecting the resulting angular momentum. A Coriolis meter is based on the principles of motion mechanics. When the process fluid enters the sensor, it is split. During operation, a drive coil stimulates the tubes to oscillate in opposition at the natural resonant frequency. As the tubes oscillate, the voltage generated from each pickoff creates a sine wave. This indicates the motion of one tube relative to the other. The time delay between the two sine waves is called Delta-T, which is directly proportional to the mass flow rate.

[008] There are further types of gas meters which use different types of sensors such as thermal sensor, hall-effect sensors, pressure sensors, CAM sensors to determine the flow rate.

[009] However, all the gas meter types have their own limitations. In diaphragm meters, the leakage from moving parts and diaphragm are the major causes for occurrence of measurement error of diaphragm meters. The rotary displacement and turbine meters have a number of mechanical parts which affects the accuracy and are prone to wear in long run. The ultrasonic flow meter and Coriolis flow meters employ complicated mechanisms and electric components which makes them expensive and complicated to use. Similarly the sensor bases gas meters need external power supply to operate the sensors, which may be unsafe and not compliant with some application areas and standards.

[0010] In view of the limitations inherent in the available gas meters, there exists a need for an improved methods and gas metering device which overcomes the disadvantages of the prior art and which can be used and manufactured in a cost effective, reliable, secure and environmentally friendly manner.

[0011] The present invention fulfils this need and provides further advantages as described in the following summary.

SUMMARY OF THE INVENTION

[0012] In view of the foregoing disadvantages inherent in the prior arts, the general purpose of the present invention is to provide an improved combination of convenience and utility, to include the advantages of the prior art, and to overcome the drawbacks inherent therein.

[0013] A primary objective of the present invention is to provide a method and device for measuring gas flow rate in a simple and cost-effective way.

[0014] In one aspect, the present invention provides a gas flow measuring device. The device comprises a housing with a gas inlet opening and a gas outlet opening, a U-shaped tube having an inlet leg and an outlet leg disposed inside the housing, a fixed member mounted in the outlet leg, a floating member disposed in the outlet leg in the path of the gas, such that the floating member is held floating vertically above the fixed member and moves vertically due to the gas flow, a magnetic field detecting sensor to detect change in magnetic field due to vertical movement of the floating member and an electronic system to convert the change in magnetic field into flow rate of gas.

[0015] In another aspect of the present invention, the outlet leg includes a diverging portion, a straight portion and a converging portion, such that the diameter of the diverging portion increases along upwards from a diameter of the outlet leg to a diameter of the straight portion and decreases along upwards from the diameter of the straight portion to the diameter of the outlet leg in the converging portion.

[0016] In yet another aspect of the present invention, the fixed member is mounted in the outlet leg below the diverging portion and the floating member is disposed in the diverging portion.

[0017] In a further aspect of the present invention, the diameter of the floating member is more than the diameter of the outlet leg, such that the floating member is held in the diverging portion without contacting the fixed member.

[0018] In one aspect of the present invention, the floating member is held floating by balancing its downward weight and a magnetic force created by a magnetic field.

[0019] In another aspect of the present invention, the floating member moves vertically when there is change in the gas flow rate and acquires a fixed position on reaching equilibrium.

[0020] In yet another aspect of the present invention, the floating member is in a form of at least one of a ball, a disc, a ring or a combination thereof.

[0021] In one aspect of the present invention, the fixed member is made of magnet and the floating member is made of a ferromagnetic material.

[0022] In another aspect of the present invention, the floating member is made of magnet and the fixed member is made of a ferromagnetic material.

[0023] In yet another aspect of the present invention, the magnetic field detecting sensor is a hall effect sensor.

[0024] In a further aspect of the present invention, the fixed member is in a form of a circular ring.

[0025] In one aspect of the present invention, the electronic system is calibrated to report gas flow rate as per change in magnetic field.

[0026] In another aspect, the present invention provides a method of measuring a gas flow rate. The method comprises guiding the gas to pass through a U-shaped tube having an inlet leg and an outlet leg disposed inside an housing, such that the gas enters vertically downwards into the inlet leg and flows vertically upwards from the outlet leg, mounting a fixed member in the outlet leg, the fixed ember is adapted to allow flowing of the gas through it, disposing a floating member in the outlet leg in the path of the gas, such that the floating member is held floating vertically above the fixed member and moves vertically due to the gas flow, detecting a change in magnetic field due to vertical movement of the floating element and converting the change the magnetic field value into gas flow rate.

[0027] These together with other aspects of the invention, along with the various features of novelty that characterize the invention, are pointed out with particularity in the description annexed hereto and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The advantages and features of the present invention will become better understood with reference to the following detailed description taken in conjunction with the accompanying drawings in which:

[0029] FIG. 1 illustrates a schematic diagram of a gas flow measuring device, according to one embodiment of the present invention;

[0030] FIG. 2 illustrates a partial cut view of the gas flow measuring device showing the U-shaped tube inside the housing, according to one embodiment of the present invention;

[0031] FIG. 3 illustrates a two-dimensional view of the U-shaped tube, according to one embodiment of the present invention;

[0032] FIG. 4 illustrates a cut view of the gas flow measuring device, according to one embodiment of the present invention; and

[0033] FIG. 5 illustrates a flowchart of a method of measuring gas flow rate, according to one embodiment of the present invention.

[0034] Like reference names refer to like parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

[0035] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details.

[0036] As used herein, the term ‘plurality’ refers to the presence of more than one of the referenced items and the terms ‘a’, ‘an’, and ‘at least’ do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.

[0037] Reference herein to “one embodiment” or “another embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Further, the diagrams representing one or more embodiments of the invention do not inherently indicate any particular order nor imply any limitations in the invention.

[0038] Referring to FIGs.1-4, that illustrate various views of a gas flow measuring device 10, according to one embodiment of the present invention. The device 10 comprises a housing 12 with a gas inlet opening 12I and a gas outlet opening 12O, a U-shaped tube 14 having an inlet leg 14I and an outlet leg 14O disposed inside the housing 12, a fixed member 16 mounted in the outlet leg 14O, a floating member 18 disposed in the outlet leg 14O in the path of the gas, such that the floating member 18 is held floating vertically above the fixed member 16 and moves vertically due to the gas flow, a magnetic field detecting sensor (not shown) to detect change in magnetic field due to vertical movement of the floating member 18 and an electronic system (not shown) to convert the magnetic field value into flow rate of gas. The gas may be natural gas or any other combustible gas whose flow rate has to be measured.

[0039] The housing 12 is in the form of a box which encloses the U-shaped tube 14 and the magnetic field detecting sensor besides the outer leg 14O of the U-shaped tube. The device 10 is connected in the pipeline where the gas flow has to be measured. On the housing 12, there is one gas inlet opening 12I from which the gas enters inside the gas measuring device 10 and a gas outlet opening 12O from which the gas exits back to the pipeline. The housing 12 may be in the form of two pieces which are connected by connecting means to form a box. The housing 12 is designed such that there is no leakage of gas from the housing 12 and also there is no leakage of any external fluid inside the device 10.

[0040] Referring to FIG. 3 that illustrates a two-dimensional view of the U-shaped tube 14, according to one embodiment of the present invention. The U-shaped tube 14 has two vertical legs 14I and 14O with an intermediate portion connecting the two legs 14I and 14O forming the U-shape. The intermediate portion may be straight horizonal or it may be curved as per the design requirements of the device 10.

[0041] The end portion of both inlet leg 14I and the outlet leg 14O of the U-shaped tube protrudes outside the housing 12, from the gas inlet opening 12I and gas outlet opening 12O respectively, such that the gas enters vertically downwards form the gas inlet opening 12I into the inlet leg 14I and flows vertically upwards from the outlet leg 14O through the gas outlet opening 12O. The end portion of both inlet leg 14I and the outlet leg 14O of the U-shaped tube includes connecting means to mount the U-shaped tube 14 inside the housing 12 and are also provided with means to connect the device 10 with a gas pipeline, such that the gas enters in the device 10 from the inlet leg 14I and flows through the U-shaped tube 14 and exits from the outlet leg 14O to the pipeline.

[0042] In one embodiment of the present invention, the outlet leg 14O includes a diverging portion 14D, a straight portion 14S and a converging portion 14C, such that the diameter of the diverging portion 14D increases along upward direction from a diameter of the outlet leg 14O to a diameter of the straight portion 14S and then decreases along upward direction from the diameter of the straight portion 14S to the diameter of the outlet leg 14O in the converging portion 14C.

[0043] The diverging portion 14D and the converging portion 14C are like hollow conical sections cut from both sides with diameters varying along the axis from one side to another. The diameter of the U-shaped tube 14 may be same throughout the inlet leg 12I, intermediate portion and the outlet leg 12O and only varies at the diverging and converging portions 14D and 14C. The diameter of the straight portion 14S may be equal to the diameter of the U-shaped tube 14.

[0044] Referring to FIG. 4, that illustrates a cut view of the gas flow measuring device 10, according to one embodiment of the present invention. The fixed member 16 is mounted in the outlet leg 14O below the diverging portion 14D and the floating member 18 is disposed in the diverging portion 14D. The diameter of the floating member 18 is more than the diameter of the outlet leg 14O, such that the floating member 18 is held in the diverging portion 14O without coming down due to its own weight and contact the fixed member 16. The floating member 18 remains above the fixed member 16 because of the geometrical shape and dimensions of the diverging portion 14D when there is no flow of gas in the U-shaped tube 14.

[0045] In one preferred embodiment of the present invention, the fixed member 16 is in the form of a circular ring. The circular ring is mounted in the wall of the outlet leg 14O and allows the gas to flow through the inner section of the ring and prevents any flow of gas from outside the periphery of the ring. The floating member 18 may be made in the form of at least one of a ball, disc, ring or a shape which is combination of these. The floating member 18 does not allow the gas to flow through it and gets displaced by the force of gas flow vertically when there is gas flowing.

[0046] In an embodiment of the present invention, the floating member 18 is held floating by balancing its downward weight and a magnetic force created by a magnetic field. The magnetic field is created by either the fixed member 16 or the floating member 18.

[0047] In one preferred embodiment of the present invention, each of the fixed member 16 and the floating member 18 are made of magnet. The magnetic fixed member 16 and floating member 18 are disposed such that, their opposite poles face each other and there is a repulsive force between them which makes them repel each other. The magnetic strength of either one of the fixed member 16 or floating member 18 is significantly different such that one magnet is weaker magnet when compared with another. For example, the fixed member 16 is a fixed magnet which is stronger magnet than the floating member 18. In this situation the downward weight of the floating member 18 is balanced by the upward magnetic force of the magnetic field created by the fixed member 16. When there is gas flow in the U-shaped tube 14, the gas flows through the fixed member 16 and the force of the gas further adds to the upward force on the floating member 18 and lifts it further vertically. The gas escapes from the space between the outer periphery of the floating member and inner wall of the diverging portion 14D or the straight portion 14S of the outlet leg 14O to flow out of the U-shaped tube 14. The floating member 18 moves vertically up and down when there is change in the gas flow rate and acquires a fixed floating position on reaching equilibrium.

[0048] In another embodiment of the present invention, one of the fixed member 16 and the floating member 18 is made of magnet and the other is made of a ferromagnetic material. In this case, there is a force of attraction between them which pulls them towards each other. For example: if fixed member 16 is made of magnet and the floating member 18 is made of ferromagnetic material say steel, then the fixed member 16 will attract the floating member 18, but because of the dimensions of the floating member 18 being more than the outlet leg 14O dimension, the floating member 18 will remain in the diverging portion 14O and will not come into contact with the fixed member 16. In one embodiment of the present invention, the magnet is may be a neodymium magnet, a samarium cobalt magnet or other magnet which serves the purpose of the magnet as per the requirements of the present invention.

[0049] Whenever there is flow of gas in vertically upward direction, the force of flowing gas will push the floating member 18 upwards against its downward weight and the downward magnetic force of the fixed member 16. The magnetic strength of the magnets used, the dimensions of the outlet leg 14O, weight of the floating member 18 are designed as per the expected flow rate values to be measured and selected such that the floating member 18 is held floating at a height when there is gas flow.

[0050] When the rate of gas flow changes, the floating member 18 may come down or move up based on reduction and increase respectively in the gas flow rate. The magnetic field detecting sensor is located outside the outlet leg 14O, such that the sensor detects a change in magnetic field due to vertical movement of the floating member 18. For a particular vertical position of the floating member 18, there is a particular value of magnetic field detected by the sensor. When the vertical position of the floating member 18 changes, the value of magnetic field also changes. This principle is used to calibrate the sensor to report magnetic field as per the position of the floating member 18 in the outlet leg 14O. The electronic system converts this magnetic field value into gas flow rate. Electronic and electrical components known in the art may be used to form the electronic system for measuring the gas flow rate as per the requirements of the device 10 of the present invention. In one embodiment of the present invention, the magnetic field detecting sensor is a hall effect sensor. The electronic system is calibrated to report gas flow rate as per the magnetic field value.

[0051] Now referring to FIG. 5, that illustrates a flowchart of a method 100 of measuring gas flow rate, according to one embodiment of the present invention. The method starts with step 110 of guiding the gas to pass through a U-shaped tube 14 having an inlet leg 14I and an outlet leg 14O disposed inside a housing 12, such that the gas enters vertically downwards into the inlet leg 14I and flows vertically upwards from the outlet leg 14O. The U-shaped tube 14 is held in the housing and has an openings for gas inlet and outlet.

[0052] Now in step 120, the fixed member 16 is mounted in the outlet leg 14O. The fixed member 16 is adapted to allow flowing of the gas through it. A floating member 18 is disposed in the outlet leg 14O in the path of the gas in step 130, such that the floating member 18 is held floating vertically above the fixed member 16 and moves vertically due to the gas flow. In one embodiment of the present invention, the floating member 18 is held floating by balancing its downward weight and magnetic force created by a magnetic field. Either one of the fixed member 16 and floating member 18 may be made of magnet and the other of ferromagnetic material which helps to generate the magnetic field. In another embodiment of the present invention, each of the members 16, 18 may be made of magnets of different magnetic strength. The magnetic force and the dimensions of the outlet leg 140 helps to keep the floating member 18 at a prespecified distance from the fixed member 16.

[0053] When the gas flows vertically upwards from the outlet leg 14O of the U-shaped tube, it changes the vertical position of the floating member 18. Initially, the floating member moves due to change in gas flow rate, but after some time it occupies another vertical position when the system reaches to an equilibrium state.

[0054] In step 140, the change in magnetic field due to vertical movement of the floating element 18 is detected. For a particular gas flow rate, there is a particular vertical position of the floating member 18 and for a particular position of the floating member 18 there is a particular value of magnetic field value which is detected. The magnetic field value is converted into gas flow rate in step 150.

[0055] The gas flow measuring device 10 and the method 100 of the present invention may provide advantages as below:
- Safety: Since there is no electrical component in the device where there is presence of gas, the device is safe from any potential sparking hazard
- Less Mechanical Components: The device eliminates need of mechanical components and improves the accuracy of the measurement
- High sensitivity: Measurement based on changes of magnetic field makes the device highly sensitive for slight variations in gas flow rates
- Compact size: Device includes only U-shaped tube and sensor in a housing which makes it very compact
- Easy installation: The device is simple and just need to be connected in a pipeline to start measurements
- Easy adaption for digital measurement and control: The electronic system gives digital data which makes the device adaptable to transfer data to remote location and with some additional sensors, the device operation may be monitored and controlled from a remote location

[0056] Although a particular exemplary embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized to those skilled in the art that variations or modifications of the disclosed invention, including the rearrangement in the configurations of the parts, changes in steps and their sequences may be possible. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as may fall within the spirit and scope of the present invention.

[0057] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.

[0058] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.