FIELD OF THE INVENTION
The present invention relates to device for Slosh removal and ultrasonic
sensor’s protection from getting wet for level measurement.
BACKGROUND OF THE INVENTION
It has been seen that there are many proposals in the past regarding
measurement of the fluid level with ultrasonic level sensors in the vehicle tanks.
In the prior arts the inventors had introduced electronic circuits and filters to their
sensors to cater for the slosh factor. This type of electronic filtering is applicable
for medium slosh conditions but when the slosh is high even filtering and
averaging doesn’t provide adequate results. Ultrasonic sensors measure the
level of the fluid by projecting high frequency audio waves directed towards the
surface of the liquid under measurement and then computing the time it requires
for the signal to return to the sensor. A rising or falling fluid level provides
different time periods thereby enabling the sensor to compute its level
effectively. Ultrasonic sensors provide good results when the surface of the fluid
is either at rest or moves slowly. However when the fluid surface moves wildly
the sensor loses tracks of the surface and provides wrong results.
In the prior arts, the inventors had introduced electrical circuits and digital/
analog filters to counter these errors. Inventors had also introduced concept of
pipe mounted on the ultrasonic sensor’s head to reduce the errors generated by
the slosh however a considerable amount of slosh also remains inside the pipe.
Motion impacts the performance of an ultrasonic level sensor, a common
phenomenon being the formation of standing waves in a fuel tank. Wave
motion creates noise in the measured data because the level sensor measures
one distance at the wave peak and another distance during the wave troughs. It
should be noted that for a typical on highway application, this difference can be
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as high as 30% of full scale. Therefore as stated above many inventors in the
past designs compensates for this difference by averaging data and processing
the result through a multi tap finite impulse filter / other filtering algorithms. The
combination of which minimizes the standing wave noise level to a manageable
level with a minimal reduction in the level sensor’s response time.
Another common and very difficult problem to handle in mobile/ highway
applications is when the fuel / liquid washes over the surface of the level
sensor . This results in altering the transducer with to depth sounder, coupling to
the fluid and then measuring the distance to the bottom of the tank and back
again. Thereby consequently increasing the speed of sound as the speed of
sound is roughly 4 times faster in a fluids with respect to air so the net result is a
false reading indicating full tank to be a quarter tank.
US7421895, Fluid level measuring system. This patent teaches a method where
the ultrasonic sensors that could be placed outside the wall of the tank at its
bottom to measure the fluid level, is in-fact placed inside a pipe and at its
bottom , the assembly can be inserted inside the fluid tank to take
measurements of the level. The fluid inside the tube is also subjected to slosh in
highway application. This slosh can also wash off the sensor surface thus
causing wrong measurements.
US5184510, Liquid level sensor, shows a method of placing a buoyantly
supported sphere in a tube to indicate correct level to ultrasonic sensor on its
top in arrangements where the tube is required to be aligned. The spherical float
enables the measurements to be take when the pipe tilts as the spherical float
remains un affected. However the clearance between the float and the pipe
walls permits slosh to wet the sensor thereby making the measurement erratic.
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US4170765, Liquid level sensor. Proposes a tube fitted with acoustic sensor at
its top having a discontinuous region in the tubing to serve as a reference for the
ultrasonic sensor . The fluid inside the tube is also subjected to slosh in highway
application. This slosh can also wash off the sensor surface thus causing wrong
measurements.
The problem to be addressed is by tapping the bottom of the fuel tank with a
small adapter and installing a narrow pipe parallel to the fuel tank with reduced
diameter such that the sensor could be placed on this pipe without taking
considerations for the tank compartments. The pipe is further provided with a
cylindrical float with plurality circular fins at its outer surface and the inner core
being plurality hollow sections identical tube in order to reduce the slosh and
prevent it from wetting the sensor on its top such that the measurements are
taken more accurately and reliably.
There are ultrasonic sensor of non-invasive type which could be mounded
beneath the tank on its tank wall and these sensors also measure the fluid
level on similar principles but the waves gets reflected from the inner surface
of the fluid. Such type of sensors can equally be benefited from the patent under
discussion.
The invention relates more particularly to ultrasonic type level sensors on
locomotive fuel tanks but not by way of limitation, to such apparatus and method
utilizing other sensors such as radar level sensors, optical or other similar types
on different type of tanks used in mobile/ vibrating applications.
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OBJECTS OF THE INVENTION
It is therefore the object of the device to enable the placement of a sensor at a
convenient location where the fluid tanks comprise of multiple compartments
and at location inaccessible for the sensors from its top side, by the
incorporation of an adapter at the bottom of the tanks and placing a parallel tube
along the length of the tank. The tube is provided with a narrow beam ultrasonic
sensor at its top to measure the level of the fluid rising or falling inside the tube
which in-fact represents the tank level. The tubing is provided with cylindrical
float with hollow sections inside and circular fins outside to stop the slosh from
causing measurement errors and wetting the transducer.
It is another object of the invention to provide a device and method to access the
fluid level inside the tanks which are inaccessible from the top surface for the
ultrasonic/ like sensors by attaching a parallel tube outside the tank.
It is another object of the invention to provide an ultrasonic sensor which uses
narrow beam for level measurement on the top end of the tube.
A further objective of the invention is to provide a cylindrical float with plurality
circular fins on its outer surface and a plurality hollow sections running along its
length.
A still further objective of the invention is to contain the slosh from wetting the
surface of the sensor.
A still further objective of the invention is to contain the rapid vertical motion of
the float by the inclusion of hollow sections running along its length.
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A still further objective of the invention is the external tube could be placed
inside the tank, if space permits, by opening the bottom surface of the tube
along with its float.
With the above and other objectives in view, as will hereinafter appear, various
embodiments of the present invention are described hereunder.
SUMMARY OF THE INVENTION
According to an embodiment of the invention, Slosh removal and ultrasonic
sensor’s protection from getting wet for level measurement, comprising; an
external tube arrangement having a tap at the bottom of the tank and ventilating
holes at its top and placed parallel to the tank, wherein the tube and the tank
works like a ‘U’ shaped tube and represents the tank level in a smaller crosssection
area with reduced slosh level; an ultrasonic sensor with narrow beam
width of measurement mounted on the top of the tube to measure the fluid level
inside the tube at any given instant of time; a float placed inside the tube
designed with plurality circular fins at its outer surface and plurality hollow
sections running throughout its length. The plurality circular fins arrangement
prevents the vertical movement of fluid along the tube walls and plurality hollow
sections running throughout its length enable the float to minimize the slosh,
thereby enabling the float to integrate the fluid level inside the tube and thus
allowing the precise measurements to be taken even in heavy sloshing
environments.
According to another embodiment of the invention, an external tubing with small
cross-section area and parallel to the tank is provided which is tapped at the
bottom of the tank such that it could be conveniently located at other place,
particularly in arrangements where the tanks are inaccessible from the top
surface for the ultrasonic/ like sensors .
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According to another embodiment of the invention, the external tube has
ventilation holes appropriately located on its top to enable this tube work like one
end of the ‘U’-shaped tube thereby representing tank level.
According to another embodiment of the invention, an ultrasonic sensor is used
which uses narrow beam for level measurement on the top end of the tube.
According to another embodiment of the invention, a cylindrical float with
plurality circular fins on its outer surface and a plurality hollow sections running
throughout its length is provided.
According to another embodiment of the invention, the float provided inside the
tube, prevents the sensor from getting wet by containing the slosh.
According to another embodiment of the invention, the outer circular fins of the
float prevent the fluid from rising along the walls of the tube.
According to another embodiment of the invention, the hollow sections running
inside the float contains the rapid vertical motion of the float.
According to another embodiment of the invention, the external tube can be
placed inside the tank, if space permits, by opening the bottom surface of the
tube including the float.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a detailed view of various components of the invention
according to an embodiment of the present invention wherein it is installed
outside the tank.
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Figure 2 shows a detailed view of the float.
Figure 3 shows a detailed view of various components of the invention
according to an embodiment of the present invention wherein it is installed
inside the tank.
Figure 4 shows a detailed view of various components of the invention
according to an embodiment of the present invention wherein it is installed
inside the tank and is interface to a non-invasive type ultrasonic sensor.
For a better understanding of the embodiments of the invention and to show
how it may be performed, it will now be described in more detail with reference
to the accompanying drawings.
DETAILED DESCRIPTION OF THE INVENTION
The present invention can be better understood by reading the following detailed
description of some of the embodiments, with reference made to the
accompanying drawings. It will be understood that a particular system
embodying the invention is shown by way of illustration only and not as a
limitation of invention. The principles and features of this invention may be
employed in various numerous embodiments without departing from the scope
of the invention. References are made to accompanying drawing in which its
novel feature and advantages will be apparent.
As can be seen in Figure 1, it shows the elements of the present invention as
attached to the main tank 9, for liquid level measurement. There are many
places where the fuel tanks are inaccessible from the top surface of the tank and
yet require non contact method of level measurement and that too in operating
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conditions which provides large amount of slosh. In a number of cases such
tanks are large and have pre-installed partition walls to reduce the slosh 13. This
makes the placement of the sensors more difficult. To overcome this problem
the present invention uses an external tube 5, which is placed parallel to the
tank having a multifold smaller diameter as compared with the tank 9, and is
connected to the bottom of the tank through connecting pipe 6, of desired length
thereby enabling the placement of the tube 5, at a location away from the tank.
The external tube 5, is provided with ventilation holes 8, on its top surface to
enable the free rise and fall of the fluid thereby working as a ‘U’ shaped tube but
with significantly reduced diameter. The external tube 5, is attached with an
ultrasonic sensor 1, at its top side emitting narrow beam of ultrasound for level
measurement. The external tube 5, reduces the slosh considerably due to its
reduced surface area as compared to its main tank 9, but is still not enough for
precise measurements, as a considerable amount of slosh 13, still prevails
inside the tube even after keeping into account its minimum possible diameter
with respect to beam width and depth of measurement. To overcome the
prevailing condition of slosh 13, inside the tube 5, a cylindrical float 3, is inserted
inside the tube comprising plurality circular fins 2, at its outer surface. It is also
disposed with plurality hollow sections 4, running throughout its length i.e. float
3. In this float 3, the plurality circular fins 2, obstructs the flow of rising fluid
along the walls of the tube 5, in any direction towards the ultrasonic sensor 1,
and the hollow sections 4, running throughout the float 3. This arrangement
helps in stabilizing the fluid 7, surface by breaking it into smaller hollow sections
4 and thereby damping the slosh inside the tube considerably, thereby enabling
precise measurements of the fuel level to be taken during the run. The
arrangement is equally applicable for non-invasive ultrasonic sensors 14, but
requires the float 3, to be inverted inside the tube 5, so that its disc 10 faces the
sensor.
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As can be seen in Figure 2, it shows the detailed view of the float 3. The float 3,
is a cylindrical shaped member of appropriate dimensions placed in the inner
diameter of the tube 5, and having plurality circular fins 2, arranged on its outer
surface with appropriate clearance 12, with the tube 5. This clearance 12, is
desirable for the free flow of the float and has tolerances so that the float doesn’t
gets struck inside the tube 5. The plurality circular fins 2, enable to keep the
clearance to the desired extent and yet obstructs the slosh from rising to the top
from its side walls. The float 3, has plurality hollow sections 4, which enables the
fluid to rise inside the hollow sections 4, which in-turn divides the surface area of
the fluid into plurality sections and minimizes the formation of slosh. The plurality
hollow sections 4, further enable to counter the rapid vertical movement of the
float with respect to the fluid thereby averaging out the sudden vertical jerks on
the float 3. The float 3, further comprise of disc 10, appropriately placed on the
top end of the float through spacers 11, providing the ultrasonic beam with a
uniform reflecting surface and causing strong echoes.
As can be seen in Figure 3, it shows the elements of the present invention as
attached to the main tank 9, for liquid level measurement, is an arrangement
where the tank 9, is accessible from its top surface. The only difference being
that the tube 5, bottom surface is provided with sufficient opening to enable the
fluid 7, to rise through it. All other measurement principles and arrangements
remain same as stated in Fig 1 above.
As can be seen in Figure 4, it shows the elements of the present invention as
attached to the main tank 9, for liquid level measurement is arrangements where
the tank 9, is accessible from its top surface. The arrangement shows the use of
non-invasive ultrasonic sensor 14, which is media isolated and duly attached at
the bottom surface of the tube 5. The float 3, in this case is inverted inside the
tube 5, so that its disc 10 faces the sensor for better reflections.
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I Claim:
1. A Slosh removal and ultrasonic sensor’s protection from getting wet for
level measurement, comprising:
an external tube (5) arrangement having a connecting pipe (6)at
the bottom of the main tank(9) and ventilating holes(8) at its top and placed
parallel to the tank; thereby enabling the placement of the external tube(5) at
any convenient location near the main tank(9);
the external tube(5) and the main tank(9) works like a ‘U’ shaped
tube and presents the tank level in a smaller cross-section area and is further
provided with a float (3); wherein
the float is shaped cylindrically including plurality circular fins on
its outer surface(2) and hollow sections (4) running inside and a flat circular disc
(10) appropriately placed on its top; Thereby
reducing the slosh inside the pipe to a significant amount and
preventing the ultrasonic sensor from getting wet ; and
an ultrasonic sensor with narrow beam width of measurement
mounted appropriately on the top of the tube to measure the fluid level, inside
the tube, precisely at any given instant of time.
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2. The device as claimed in any one of the preceding claims, wherein an
external tube (5) disposed parallel to the main tank (9) and connected to
its bottom with a long connecting pipe(6) such that the external tube (5)
could be placed conveniently away from the main tank(9).
3. The device as claimed in any one of the preceding claims, wherein the
external tube(5) has ventilation holes (8) conveniently located at its top to
enable it work like one end of the ‘U’-shaped tube thereby representing
tank level in a reduced cross-sectional area.
4. The device as claimed in any one of the preceding claims, wherein top
end of the external tube (5) is mounted with an ultrasonic sensor(1) which
uses narrow beam width frequency for level measurement .
5. The device as claimed in any one of the preceding claims, wherein the
device could be used with sensors such as radar, laser, optical levels
sensors mobile or stationary vibration prone operating environments for
measuring levels of fluids like fuels, liquefied gases , water etc.
6. The device as claimed in any one of the preceding claims, wherein the
tube (5) with an appropriate hole at its bottom can also be mounted
inside the tank, if its top surface is accessible.
7. The device as claimed in any one of the preceding claims, wherein the
shape of float(3) is cylindrical comprising plurality circular fins(2) on its
outer surface and a plurality hollow sections running along its length(4)
and is dimensioned to have 1~5mm clearance (12) with respect to the
tube(5) walls.
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8. The device as claimed in any one of the preceding claims, wherein the
float(3) prevents the sensor from getting wet or washed by the fluid.
9. The device as claimed in any one of the preceding claims, wherein the
float(3) is provided with a flat disc (10) of matching dimensions on the top
surface and at a distance of 2~ 8mm through spacers(11) to provide even
surface to the reflected ultrasonic waves.
10. The device as claimed in any one of the preceding claims, wherein the
float(3) with circular fins(3) can be used for lower slosh applications
omitting the disc(10) and hollow sections (4) running along its length.
11. The device as claimed in any one of the preceding claims, wherein the
float (3)is equally applicable for non-invasive (through the wall) ultrasonic
sensor (14) mounted at the bottom of the tube (5) with the disk (10)
mounted at the bottom side of the float(3).
12. A device for Slosh removal and ultrasonic sensor’s protection from
getting wet for level measurement, substantially as herein described and
illustrated in the figure 1, figure 2, figure 3 and figure 4 of the
accompanied drawings.
Dated this 16th day of March, 2012.