Note: Descriptions are shown in the official language in which they were submitted.
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Docket No. 155.00075
RESISTANCE MILK FLOW SENSOR
Field of the Invention
This invention relates to milk flow sensors and more
particularly to resistance milk flow sensors.
Background Art
Prior art resistance milk flow sensors measure
resistance between two electrical conductors separated
by an insulator and located in a milk line. Milk flowing
across the conductors decreases the resistance between
the conductors and a circuit connected to the conductors
measures the resistance to determine milk flow.
Prior resistance flow sensors include first and
second sections of electrically conductive tubing
connected together by a cylindrical insulator such as
plastic. First and second leads connect the first and
second sections of tubing to a circuit which measures
electrical resistance. The first section of tubing, the
insulator, and the second section of tubing are connected
consecutively in a milking line.
These resistance milk flow sensors have crevices at
junctions between the first and second sections of tubing
and the insulator. Milk collects in the crevices during
use and the crevices are difficult to clean. Some of the
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prior resistance flow sensors require labor-intensive
disassembly for proper cleaning.
Other prior resistance flow sensors include first
and second probes which project inside the milk flow
lines. The probes are connected to a circuit which
measures resistance therebetween.
This type of intrusive milk flow sensor also has the
drawback that milk collects around the projecting probes.
SummarY of the Invention
A non-intrusive milk flow sensor includes first and
second cylindrical nipples of a conductive material.
Each of the first and second cylindrical nipples has an
inner diameter. A molded rubber body has a passage
therethrough joining the first and second nipples. The
body fixes the first cylindrical nipple inline with the
second cylindrical nipple. The body has an inner
diameter defined by the passage equal to the inner
diameter of the first and second cylindrical nipples.
The molded rubber body insulates the first cylindrical
nipple from the second cylindrical nipple. A first
electrical lead is connected to the first cylindrical
nipple. A second electrical lead is connected to the
second cylindrical nipple.
It is a feature of the invention that the first and
second electrical leads are coated with silicone.
In a further feature of the invention, the first and
second cylindrical nipples are of stainless steel.
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In still a further feature of the invention, the
first and second cylindrical nipples include a radially-
extending annular flange at facing ends.
Other objects, features and advantages will be
readily apparent.
Brief DescriPtion of the Drawings
Figure 1 is a plan view of a resistance milk flow
sensor;
Figure 2 is a plan view of a partially assembled
resistance milk flow sensor; and
Figure 3 is a cross-sectional view of a tubular body
and first and second nipples of the resistance milk flow
sensor.
Detailed Description of the Preferred Embodiment
In Figure 1, a milk flow sensor 10 includes first
and second cylindrical nipples 14, 16 and a tubular body
18. The milk flow sensor 10 can be connected to milk
lines to receive milk flowing from a teat cluster
attached to teats of a milking cow.
The milk flow sensor 10 also includes a bracket 20
for mounting the milk flow sensor 10 to a support by a
bolt (both not shown). The bracket 20 includes a planar
section 22 which is mounted on the support and an arcuate
section 24 which supports and is formed around the
tubular body 18.
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Figure 2 shows a partially assembled view of the
milk flow sensor 10. An assembly fixture (not shown)
holds the first and second nipples 14,16 in line and
maintains a gap between the first and second nipples 14,
16 during assembly. A heat resistant and insulating
sleeve 28 houses first and second electrical leads 30,
32. A hose clamp 34 is crimped flush with an outside
surface of the sleeve 28. The clamp 34 prevents damage
to the sleeve 28 during assembly and holds the first and
second leads 30,32 together.
The first lead 30 is initially threaded through a
hole 36 in a radially projecting annular flange 38 of the
second nipple 16. The first lead 30 is then threaded
through a hole 42 into a radially projecting annular
flange 44 on the first nipple 14. A ring terminal 46 is
crimped to an end of the first lead 30. Finally, a screw
48 inserted through the ring terminal 46 and into a
threaded hole 50 fastens the first lead 30 to the annular
flange 44 on the first cylindrical nipple 14.
A ring terminal 54 is crimped to an end of the
second lead 32. A screw 56 inserted through the ring
terminal 54 and into a threaded hole 58 fastens the
second lead 32 to the annular flange 38 on the second
cylindrical nipple 16.
Both the first and second leads 30, 32 are coated
with a heat resistant and insulating material.
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After fastening the first and second leads 30, 32 to
the first and second nipples 14, 16, the tubular body 18
is formed.
In Figure 3, a cross-sectional view of the tubular
body 18 and the inline first and second nipples 14,16 is
shown. For illustration purposes, the first and second
leads 30, 32, the ring terminals 46, 54, the sleeve 28,
the holes 36, 42, 44, 58 and the screws 48, 56 are not
shown. It is to be understood that these parts would be
located inside the tubular body 18.
A passage 63 defines an inner diameter 64 of the
tubular body 18 and is formed flush with inner diameters
66 of the first and second nipples 14,16 to prevent milk
buildup which causes cleaning problems.
A circuit (not shown) connected to the first and
second leads 30,32 measures resistance between the first
and second nipples 14,16. As milk flows across the first
and second nipples 14,16, the resistance decreases. The
circuit detects the decrease to measure milk flow.
The tubular body 18 can be of molded rubber, for
example neoprene. The nipples 14, 16 are constructed
from a hygienically innocuous material such as stainless
steel, platinum, carbon, etc. If the nipples are of
stainless steel, the body is preferably formed of molded
rubber since plastic will not bond to stainless steel. A
bonding agent adheres the molded rubber to the stainless
steel nipples. CHEMLOCR~ manufactured by Lord Chemical
Co. in Erie, Pennsylvania is a suitable bonding agent.
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The insulating and heat resistant coating on the
leads 30,32 and the sleeve 28 are preferably of silicone
which can withstand heat of molten rubber applied during
assembly. SILFLEX~ manufactured by Olflex Cable and Wire
Co. in Fairfield, Connecticut can be used for the sleeve
and the coating.
The annular flanges 38,44 prevent the nipples 14,16
from being removed from the body 18 after the body is
formed and provide a mounting surface for the screws
48,56.
The ring terminals 46, 54 and screws 48, 56 are used
instead of soldering to provide a stronger mechanical
connection between the first and second leads 30,32 and
the first and second nipples 14,16. For example, the
first and second leads 30,32 are typically of copper,
while the nipples 14,16 are of stainless steel. Because
of different materials used for the nipples and leads,
soldering provides insufficient mechanical strength to
reliably withstand stress encountered when the tubular
body is molded.
For optimum operation, the sensor is mounted at 45
degrees. First and second bevels 70, 72 inclined 45
degrees with respect to a horizontal edge 74 on the
bracket 20 provide a convenient reference for mounting.
Depending upon the direction of flow, either the first or
second bevel 70, 72 is leveled to obtain a desired
orientation for the sensor 10.
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As can be appreciated, by forming the body with the
passage defining the inner diameter equal to the inner
diameters of the nipples, crevices which cause milk
buildup are avoided.
