Title of Invention

" A FLUID FLOW SENSOR USING CENTRIFUGAL FORCE TYPE FLOW TRANSDUCER"

Abstract

This invention relates to a low-cost, user-friendly fluid flow sensor using centrifugal force type flow transducer, comprising: (a) a common balance swinging on a fulcrum (1) and having an weighing tray (2) and a second tray (3) for placing weights; (b) a hollow u-tube (4) carrying bellows (5) on the upper parts of both limbs and having two bent portions serving as inlet (6) and outlet (7) for the fluid flowing through it; (c) a soft iron core (8) attached to one of the pans (2) and capable of executing vertical movement in the upward or downward direction through an opening provided in the upper surface of an inductive pick-up coil (9) in the form of a receptacle placed inside a laminated core (10) around the said pick-up coil, carrying lead wires (11) for attachment with a Maxwell's bridge arrangement, and said core (10) has a magnetic shielding (12). Figs. 2 and 4 of the drawings illustrate the invention.

Full Text

The present invention relates to a fluid flow sensor using centrifugal force type flow transducer. More particularly this invention pertains to a system or arrangement for accurately measuring the rate of flow of a fluid through a pipeline which is one of the most important requirements in any process plant in order to run the plant at optimum efficiency resulting in higher output with consequent cost saving. Heretofore various effects like the effect of energy associated with a fluid flowing through a pipeline have been attempted to be utilized, such as for instance, Doppler effect and effect of speed of the fluid on the rate of flow and the like, in designing various flow meters. In the coriolis flow meter, the effects of velocity of a flowing fluid and the extent of vibration of a pipeline section through which the fluid flows are put to use to produce a coriolis force which acts on the pipe wall in the opposite directions in the upstream and downstream sides. As a result, the resultant oscillation of the upstream side will lag with respect to the centre of the pipeline section, and that of the downstream side will lead. The delay in time between the vibrations of these two sides is directly proportional to the mass flow rate, and the results in an accurate measurement of the flow rate. Effect of different factors like properties of fluid, operating conditions, installation technique, etc. on coriolis mass flow meters have been studied and improved versions of such flow meters have been designed. In anemometer type mass flow meters, the cooling effect of a flowing fluid on a heating element inside the fluid is utilized in terms of change in resistance of the element with flow rate. In the vortex flow meter, frequency of vortices produced behind a blunt post in a pipeline under the turbulent condition is directly proportional to the volume flow rate of the fluid passing through the pipeline. B. Rodgers and his co-workers (IEEE Journal of Solid State Circuits, Vol. 33, No.12, pp.2121-2133, 1998) have developed a flow sensor module consisting of an application-specific-integrated-circuit (ASIC) with a fluidic oscillation element and a differential capacitive pressure sensor (SCS) mounted in a sealed aluminium casing. N. Svedin and his co-workers (Journal of Microelectromechanical Systems, Vol, 12, No.6, pp 937-946, December 2003) have developed a micro machined silicon torque sensor which senses the torque produced at the bearing surface of static turbine placed in a flow tube, and have shown that this torque is linearly related to the volume flow rate through the pipeline. Despite sensitivity of the instruments and reproducibility of the results obtained, the instruments in question require careful handling and periodic servicing,-apart from being costly and power — intensive. This invention aims at overcoming the above drawbacks of the prior art and provides a novel type of flow sensor which is simple in construction, easy to operate and is cost-effective. The principal objective of this invention is to provide a fluid flow sensor using centrifugal force type flow transducer. Another object of this invention is to provide a fluid flow sensor which incorporates simple components like common pan-balance for measuring the rate of flow of fluid through a pipeline. Yet another object of this invention is to provide a fluid flow sensor which is fabricated from simple components available indigenously, is user friendly and cost-effective. The foregoing objects are achieved by the present invention which relates to a fluid flow sensor using centrifugal force type flow transducer, comprising- (a) a common balance swinging on a fulcrum and having an weighing tray and a second tray for placing weights; (b) a hollow u- tube carrying bellows on upper parts of both limbs and having two bent portions serving as inlet and outlet for the fluid flowing through it; (c) a soft iron core attached to one of the pans and executing vertical movement in the upward or downward direction through an opening provided in the upper surface of a container/receptacle; (d) the said container or receptacle being provided with inductive pick-up coil carrying lead wires for attachment with a Maxwell's bridge arrangement which in turn is provided with a magnetic shielding to eliminate any extraneous interference. Theoretical consideration in respect of the present invention and the drawings accompanying these specifications are referred to hereinafter for illustrating the invention. Let us consider a fluid of density 'p' flowing with a velocity V through a semi-circular cylindrical pipe of radius r and cross-section 'A' placed in a vertical plane as shown in Fig. 1 of the accompanying drawings. Let us consider an elementary length ds=rd8of the circular pipe at an angle 0 from the horizontal X-axis as shown in Fig.1 of the drawings. The centrifugal force by this element acting radially outwards is given by In order to measure this force and reduce the effect of turbulence, the two ends of the above semicircular pipe line section are extended in the form of the straight long vertical pipe line sections so that the sensor takes the form of a vertical U-tube section as shown in Fig. 2 of the drawings. This U-tube is connected with the main pipeline through metallic or non-metallic bellows junctions and rests on the pan at one end of the beam of a common balance as shown in this figure. At no flow condition of the fluid, the beam is made horizontal by placing fixed dead weights on the weighing pan at the other end. The end carrying the U-tube section is rigidly attached with the soft iron core of an inductive pick-up coil as shown therein. When the liquid flows through this U-tube section via the bellows junction, the upper straight part of the U-tube reduces the turbulence of the liquid and the lower semicircular part senses the centrifugal force produced by the fluid. So when the fluid flows, the end of the beam of the common balance carrying the U-tube section moves downwards along with the core of the inductive pickup coil by the action of the centrifugal force as shown in equation no. (6).The pickup coil consists of two parallel magnetic paths which decreases the effective reluctance and hence increases the sensitivity of the coil. This pickup coil is connected to one of the ratio arms of a Maxwell's bridge circuit as shown in Fig. 3 of the drawings, whereas the other end of the ratio arms consists of identical dummy inductance coil so that at no flow condition of the fluid, the bridge is almost at balanced condition when the resistances in the other ratio arms are identical. From the construction of the pickup coil as shown in Fig.2 of the drawings, it is found that the coil along with its movable core has two parallel magnetic reluctance paths like a shell type transformer. The effective reluctance 'R' of this magnetic circuit is given by where x1=x0+Δx,µ=reIative permeability of the movable core material, µ1=relative permeability of iron frame material, A=effective area of the movable core, Ai=effective area of the magnetic path in the frame material, Ll=effective length of the magnetic path in the frame at one side, d=length of the small air gap between the core and the frame, X0=length of the core at no flow condition inside the pickup coil and Δx = displacement of the core U-tube due to the centrifugal force produced by the flow. Hence a fluid flow rate 'Q, the effective magnetic reluctance of the coil can be written as where, K1 and K2 are constants given by where n is the number of turns of the coil. Since L»Δx, so from eqns. (9) and (10), K1»K2 Δx. Hence the above equation is reduced to where Lx0=n2/K1 is the inductance of the pickup coil at no flow condition and ΔLx =n2K2Δx/K12 is the change in inductance of this coil due to the fluid flow through the pipeline. From Fig. 3 of the drawings the bridge output voltage Eo for sinusoidal supply voltage Vs is given by Now the bridge is balanced at no flow condition when the beam of the common balance is horizontal so that R2LX0=R1L0. Hence putting this condition in the above equation, the bridge output at flow condition of the fluid is given by Now the displacement Ax of the core is due to the centrifugal force (Fy) only. Since the beam of the balance is initially made horizontal at no flow condition of the fluid and the centrifugal force due to the flowing liquid is generally small, so the displacement Ax of the core may be assumed to be directly proportional to the centrifugal force (Fy). where K3 is the constant of proportionality. Combining the foregoing eqn. nos. (6), (15) and (16) one would arrive at - Hence for a given fluid the bridge output will have almost a parabolic relation with the fluid flow rate (Q) As mentioned earlier, the invention is illustrated by the accompanying drawings, wherein Fig. 1 represents semicircular pipe line section; Fig. 2 shows a centrifugal force type flow transducer is fully assembled form; Fig. 3 shows the Maxwell's bridge circuit for sensing displacement of the flow-sensing U-tube section; Fig. 4 depicts the experimental set-up for testing this proposed flow sensor in the form of a flow-chart; Fig. 5 is the static characteristic graph of the proposed flow sensor and Fig. 6 shows the percentage deviation graph from best fit static characteristic of the flow sensor. The subject invention will now be further described in specific details by means of the undernoted working example which is given by way of illustration and not by way of limitation. Example The flow sensor of the subject invention has been designed and fabricated by using a common pan balance and a U-tube flow sensor made from 12mm (0.5 inch) dia PVC tube. The lower semi-circular part of the U-tube has a mean diameter of around 100mm and length of the vertical parts of the U-tube is around 250mm. This U-tube is connected with the main 25mm (1") dia. water supply line through bellows usually made of metal, as illustrated in Fig. 2 of the drawings. The U- tube is placed vertically on one of the weighing pans at one end of the beam of a common balance and on the other pan suitable weights are placed so that the beam is horizontal when there is no flow of water through the U-tube which is filled with water at rest. Under this condition the soft iron core attached to the bottom of the pan carrying U-tube assumes a particular position inside the inductive pick-up coil upto a length X0, as shown in Fig. 2 of the drawings. Next values of resistance R1 and R2 in the ratio arm of the Maxwell's bridge as shown in Fig. 3 of the drawings are adjusted until the bridge output is minimum. The bridge output is measured with the help of a multimeter and a cathode ray oscillograph (CRO) as the detector. The foregoing experimental setup has been illustrated in the form of a sequential flow- sheet diagram in Fig. 4 of the drawings. In the aforesaid experimental set-up, an overhead water tank is maintained at a constant level by ensuring that the rate of inflow is greater than the exhaust rate of water. Water from this tank is allowed to flow into the U-tube sensor through a valve, usually operated manually. Flow through the U-tube is changed in steps of increasing and decreasing modes, and at each step the bridge output is measured. The flow rate is monitored by direct water collection procedure, and results obtained are found to be reproducible and identical The bridge output voltage has been plotted against flow, giving rise to a parabolic static characteristic graph as shown in Fig. 5 of the drawings. The percentage deviation of the experimental data from the best-fit prabolie characteristics has been calculated, a plot of which is shown in Fig. 6 of the drawings. The static characteristic graph of the flow sensor of the present invention as shown in Fig. 5 of the drawings has a parabolic nature, which substantially follows and conforms to equation (17} given above. In the course of increasing and decreasing modes of experiments, identical results were obtained for the same flow rate, and this establishes a satisfactory repeatability of the flow sensor. The non-linear characteristic graph can be easily lenearised by using microprocessor or PC-based linearization technique developed by the Applicant and his co- workers. Advantages: (i) Construction of the transducer is very simple, and measurements involve no contact with the process fluid, (ii) Fabrication of the equipment or part(s) thereof can be done by using material(s) and machineries available indigenously, resulting in a very cost-effective, user-friendly transducer, particularly when compared with the existing sophisticated flow meters like coriolis-flow meter, vortex flow meter etc. (iii) Use of bellows element is another unique feature of the invention, selection of which may be conveniently varied, depending on the pressure of the fluid material flowing through the sensor; (iv) Compactness of the transducer may be further enhanced by using a compact lever system in lieu of the common pan balance; (v) From equation (6) given earlier, it follows that the sensitivity of the sensor increases with the reduction of the cross-sectional area (A) of the sensing pipe. Hence to measure flow rate in large diameter pipeline, a flow sensor of very small cross-section may be used in a by-pass line of the main pipe line and a suitable correction factor may be applied for the flow rate measurement in a large pipe line, which is further evidence of the versatility of the transducer of the present invention. As the present invention may be embodied in several forms without departing or deviating from the spirit and/or essential characteristics thereof, it should also be understood that the above-described example is not limited by any of the details of the foregoing description, unless otherwise specified, bat rather should be construed broadly within its spirit and scope as defined in the appended claims and, therefore, all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims. I claim: 1. A fluid flow sensor using centrifugal force type flow transducer, comprising: (a) a common balance swinging on a fulcrum (1) and having an weighing tray (2) and a second tray (3) for placing weights; (b) a hollow u-tube (4) carrying bellows (5) on the upper parts of both limbs and having two bent portions serving as inlet (6) and outlet (7) for the fluid flowing through it; (c) a soft iron core (8) attached to one of the pans (2) and capable of executing vertical movement in the upward or downward direction through an opening provided in the upper surface of an inductive pick-up coil in the form of a receptacle; (d) the said receptacle-form inductive pick-up coil (9) surrounding the soft iron body (8) is placed inside a laminated core (10) around the said pick-up coil (9), which carries lead wires (11) for attachment with a Maxwell's bridge arrangement, and said laminated core in turn is provided with a magnetic shielding (12) to eliminate any extraneous interference. 2. A fluid flow sensor as claimed in Claim 1, wherein the U-tube of the sensor (4) is placed vertically, on one of the weighing pans (2) at one end of the beam of a common balance and dead weights are placed on the other pan (3) to make the beam horizontal when there is no flow of water through the said U-tube filled with water. 3. A fluid flow sensor as claimed in Claims 1 and 2, wherein a fluid flowing through the semi-circular pipeline section (4) produces a centrifugal force due to the circular motion of the fluid acting in a vertically downward direction, which force is utilized to produce displacement of the soft iron core (8) of inductive pick-up coil (9), thereby changing the inductance of the pick-up coil and output of this bridge network of a Maxwell's bridge circuit. 4. A fluid flow sensor as claimed in Claims 1 to 3, wherein the pick-up coil (9) consists of two parallel magnetic paths and is connected to one of the ratio arms of a Maxwell's bridge circuit, whereas the other ratio arm carries an identical dummy inductance coil. 5. A fluid flew sensor as claimed in any of the preceding claims, wherein the U-tube (4) is formed from 12mm (0.5") dia PVC. 6. A fluid flow sensor as claimed in Claim 1-5, wherein the bridge output voltage is measured by using a 4.5 or 5.5 digit multimeter and cathode ray oscillograph (CRO) as the detector. 7. A fluid flow sensor using centrifugal force type flow transduce, substantially as hereinbefore described and illustrated with reference to the accompanying drawings. ABSTRACT No. 1040/KOL/2005 Filed on - 21. 11. 2005 Title - "A fluid flow sensor using centrifugal force type flow transducer" This invention relates to a low-cost, user-friendly fluid flow sensor using centrifugal force type flow transducer, comprising: (a) a common balance swinging on a fulcrum (1) and having an weighing tray (2) and a second tray (3) for placing weights; (b) a hollow u-tube (4) carrying bellows (5) on the upper parts of both limbs and having two bent portions serving as inlet (6) and outlet (7) for the fluid flowing through it; (c) a soft iron core (8) attached to one of the pans (2) and capable of executing vertical movement in the upward or downward direction through an opening provided in the upper surface of an inductive pick-up coil (9) in the form of a receptacle placed inside a laminated core (10) around the said pick-up coil, carrying lead wires (11) for attachment with a Maxwell's bridge arrangement, and said core (10) has a magnetic shielding (12). Figs. 2 and 4 of the drawings illustrate the invention.

Documents:

1040-KOL-2005-(11-11-2011)-ABSTRACT.pdf

1040-KOL-2005-(11-11-2011)-AMANDED CLAIMS.pdf

1040-KOL-2005-(11-11-2011)-CORRESPONDENCE.pdf

1040-KOL-2005-(11-11-2011)-DESCRIPTION (COMPLETE).pdf

1040-KOL-2005-(11-11-2011)-FORM 1.pdf

1040-KOL-2005-(11-11-2011)-FORM 13.pdf

1040-KOL-2005-(11-11-2011)-FORM 2.pdf

1040-kol-2005-abstract.pdf

1040-kol-2005-claims.pdf

1040-KOL-2005-CORRESPONDENCE 1.2.pdf

1040-KOL-2005-CORRESPONDENCE 1.3.pdf

1040-KOL-2005-CORRESPONDENCE-1.1.pdf

1040-kol-2005-correspondence.pdf

1040-kol-2005-description (complete).pdf

1040-kol-2005-drawings.pdf

1040-KOL-2005-EXAMINATION REPORT.pdf

1040-kol-2005-form 1.pdf

1040-KOL-2005-FORM 13.pdf

1040-kol-2005-form 18.pdf

1040-kol-2005-form 2.pdf

1040-kol-2005-form 3.pdf

1040-KOL-2005-GRANTED-ABSTRACT.pdf

1040-KOL-2005-GRANTED-CLAIMS.pdf

1040-KOL-2005-GRANTED-DESCRIPTION (COMPLETE).pdf

1040-KOL-2005-GRANTED-DRAWINGS.pdf

1040-KOL-2005-GRANTED-FORM 1.pdf

1040-KOL-2005-GRANTED-FORM 2.pdf

1040-KOL-2005-GRANTED-SPECIFICATION.pdf

1040-KOL-2005-OTHERS 1.1.pdf

1040-KOL-2005-OTHERS 1.2.pdf

1040-kol-2005-pa.pdf

1040-KOL-2005-REPLY TO EXAMINATION REPORT 1.1.pdf

1040-kol-2005-reply to examination report.pdf

1040-kol-2005-specification.pdf