Inflation for a teat cup

An inflation for a teat cup is made in the form of a silicone tube adapted to fit into, and seal the ends of, a teat cup. Pulsating pressure is applied to the outside of the inflation within the teat cup, and a low pressure line is attached to the downstream end of the inflation. An integral annular bead is spaced slightly less than a teat's length below the upstream end of the inflation. Axial ribs are spaced around the circumference of the tube upstream of the annular bead. The bead and ribs are resistive of collapse and therefore provide a gentle massaging action on the teat when the pulsating pressure is applied. In one important embodiment, the head of the inflation is provided with a pliant skirt and an annular cushion that fit against the teat and udder to minimize irritation and maximize retention of the inflation.

This invention relates to teat cups for milking machines, and more 
particularly to improved resilient tubular liners, or inflations, for such 
teat cups. 
BACKGROUND OF THE INVENTION 
A teat cup for a milking machine is an annular rigid shell with a port for 
attachment to a pulsating pressure line, as described generally in D. O. 
Noorlander, U.S. Pat. No. 3,096,740 and also as shown in T. W. Erbach, 
U.S. Pat. No. 4,269,143. 
An elongated, resilient, tubular liner, called an inflation, fits inside 
the cup. The inflation is longitudinally stretched and secured between the 
ends of the cup to provide a substantially airtight chamber between the 
outside of the inflation and the inside of the cup. The port communicates 
with the chamber. A tubular part of the inflation may project outwardly of 
the downstream end of the cup for attachment to a milking line which is 
subjected to a substantially constant sub-atmospheric pressure. The 
tubular part thereby communicates the sub-atmospheric pressure to the 
interior of the inflation, the upstream opening of the inflation being 
sealed off by insertion of a teat. A pulsating vacuum line connected to 
the port communicating with the chamber carries a pressure which 
alternates between a higher pressure, typically atmospheric, and a lower 
pressure which will generally not be greater than the constant 
sub-atmospheric pressure applied to the vacuum milking line. When the 
higher pressure is applied to the airtight chamber there is an 
over-pressure on the exterior of the inflation. The inflation collapses, 
at least partially, in response to the overpressure. 
The upstream end of the inflation may be a retaining skirt which is 
constructed to stretch fit over the upstream end of the cup to provide an 
airtight seal, as disclosed in U.S. Pat. No. 3,096,740, Near the 
downstream end of the inflation are one or more external integral annular 
ribs which are larger in diameter than the internal diameter of the 
downstream end of the teat cup. Accordingly the inflation is stretched 
axially between the upstream and downstream ends of the teat cup, and the 
annular rib is tensioned against the teat cup lower end to provide an 
airtight seal. Extending inward from the skirt is a resilient annular 
flange portion for receiving the teat and holding it during the milking 
operation. 
Such annular flange is disclosed in U.S. Pat. No. 3,096,740 and also in J. 
Maier, U.S. Pat. No. 4,141,319. As disclosed in those patents, the inner 
periphery of the annular flange bends downward to receive the teat and 
hold it in the teat cup, with the intention of providing a milking 
movement in response to the periodic pressure changes produced by the 
pulsating vacuum. The annular flange is, for this purpose, made to be very 
flexible, as disclosed in D. F. Siddal, U.S. Pat. No. 3,474,760, in 
connection with an inflation of unitary construction. 
In U.S. Pat. No. 3,096,740 an integrally formed external annular rib is 
provided around the exterior of the inflation, axially located in the 
middle section. A resilient sleeve surrounds the part of the inflation 
above the rib. The sleeve is intended to provide tension when a teat is 
inserted into the inflation, in order to grip the teat. 
Known inflations have a number of drawbacks, including inadequate retention 
on the teat, uncomfortable and dangerous irritation and injury to the teat 
and udder, and short useful lifetimes due to wear and breakage. 
Heretofore, tightly fitting inflations with correspondingly good retention 
characteristics caused the greatest teat irritation and injury, as a 
result of the tightness of the fit. A need therefore exists for an 
inflation which will hold securely to the teat during milking without 
causing irritation or injury either during milking or upon removal of the 
inflation. Inflations previously constructed from rubber have had 
lifetimes of the order of a thousand or so milkings. The rubber sleeve in 
U.S. Pat. No. 3,096,740, for example, had to be shielded by the inflation 
from the milk in the inflation in order to preserve the sleeve's 
elasticity. More recently, with the advent of silicone inflations, the 
lifetime has increased by a factor of about five. Nevertheless, it would 
be highly desirable to yet further increase the durability and hence the 
average lifetimes of silicone inflations by optimizing their design.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
As illustrated in FIG. 1, a teat cup inflation assembly 10, constructed in 
accordance with principles of the present invention, may have the form of 
a conical, frustum shaped, resilient inflation tube 12 made of silicone 
rubber, with an external wall 13. A head structure 14 at the wider, or 
upstream end of the conical frustum, comprises an annular body constructed 
to fit over the upstream end of a rigid, preferably metal, teat cup 15, to 
provide a sealed fit. An annular rib, or bead, 16 near the lower end of, 
and protruding outwardly from, the wall 13 is to be pulled through the 
lower, or downstream end of the teat cup, so that when assembled, as seen 
in FIG. 1, the bead 16 is tensioned against the teat cup's lower edge to 
provide another sealed fit. Accordingly, the space between the inflation 
wall 13 and the teat cup 15 provides a chamber to which a pulsating 
pressure may be applied through a tubular extension 15a of rigid teat cup 
15. 
The lower end 18 of the inflation 12, below the annular bead 16, is made 
relatively less resilient by providing the end with relatively thick 
walls, as shown in FIG. 1. Accordingly the less resilient lower end 18 is 
adapted for connection to a low pressure milking line, which may be, as 
known in the art, a hose connected to a vacuum pump. 
An annular transverse flange 30, integral with the head structure 14 of the 
inflation 12, projects inwardly from the head structure at the upstream 
end of inflation 12. As shown in FIG. 1, the design of head structure 14 
permits the outer circumference of flange 30 to exceed the circumference 
of cup 15. The resulting breadth of flange 30 lends enhanced flexibility 
to the flange. The annular flange 30 surrounds an opening having a size 
suitable for insertion of a cow's teat, with the lower end of the teat T 
projecting into the interior of the inflation's tube 12. The size of the 
opening within the flange 30 is such that when the teat is inserted and 
low pressure is applied to the end 18 of the inflation, the upstream end 
of the tube is sealed by the presence of the teat therein, and suction is 
accordingly applied to the lower end of teat T. The enhanced flexibility 
of flange 30, on the other hand, minimizes teat irritation. 
The tube 12 thickens into an integral, exteriorly located, annular bead 32 
spaced slightly less than a teat's length below the flange 30. The spacing 
cannot be made precise because teats are generally of different lengths, 
varying from individual to individual, and from herd to herd. Accordingly, 
inflations are made with a variety of spacings between the annular bead 32 
and the flange 30 so that suitable inflations may be selected for each 
cow. The annular bead 32 inhibits collapse of the upper portion of tube 12 
when an external overpressure condition occurs, that is, when the pressure 
on the outside of the inflation wall 13 exceeds the pressure on the inside 
of the wall. This ensures that the stronger massaging action is applied to 
the teat at the upper end of the inflation, nearer the udder. 
A plurality of axially elongated, circumferentially spaced, ribs, such as 
is illustrated by rib 40, seen in transverse section in FIG. 2, comprise 
thickened portions of the tube 12. The ribs 40 are equally spaced 
circumferentially from each other around the circumference of the tube 12 
and extend axially between the annular bead 32 and the head structure 14. 
The ribs provide circumferentially spaced, axial stiffeners, separated by 
relatively thin walled regions 41, defined in the upper part of the tube 
12. Accordingly, when external overpressure is applied to the tube 12 the 
upper part of the tube collapses by buckling of some of the thin walled 
regions 41 inwardly, and at least some of the ribs 40 then press radially 
inwardly against the teat to provide a massaging action. The massaging 
action is gentle because the ribbed construction provides means adapted to 
inhibit total collapse of the upper portion of the teat cup against the 
teat. 
By contrast, the lower part 34 of the tube 12 is not provided with 
stiffening ribs such as rib 40. Under action of external overpressure 
applied to the tube 12, the lower part 34 of inflation 12 will buckle 
along part of its length below the lower end of teat T. The buckling will 
cause the wall 13 of inflation 12 to pinch inwardly along a diametric line 
below the lower end of the teat as illustrated by the dotted line 70 in 
FIGS. 1 and 3. The pinching seals off the lower terminus of teat T, as 
shown in phantom in FIG. 1, from the suction caused by the low pressure 
applied to the lower end 18 of the teat cup, thereby providing a rest 
period for the teat from the suction applied to the teat. 
A second embodiment of an inflation embodying principles of the present 
invention is illustrated in FIG. 4. This embodiment includes means for 
enhancing the retention of the inflation on the teat, for enhancing the 
sealing of the top of the inflation to the udder and for minimizing 
irritation to both the teat and the udder. 
Retention and sealing are enhanced and irritation minimized by increasing 
contact area and decreasing transmitted wall pressure. It is noted in this 
connection that PF=TWP.times.CA, wherein PF is "pull force" or the force 
which will pull the inflation from the teat, TWP is "transmitted wall 
pressure", and CA is "contact area". As apparent from the figures and as 
explained below, contact area is increased in this embodiment, permitting 
transmitted wall pressure (a primary source of irritation) to be reduced 
while maintaining or increasing the pull force. 
In the alternate construction shown in FIG. 4 the transverse flange 30' is 
shaped, as illustrated, to extend inwardly from head structure 14 and to 
then turn downwardly to provide an innermost portion, or skirt, 50, which 
has significantly greater contact area (CA) than the inner periphery of 
the opening in flange 30 of the embodiment of FIG. 1. Accordingly, the 
transmitted wall pressure along the area of contact to the teat can be 
reduced by yet further widening the flange and increasing its resiliency. 
In fact, as shown in FIG. 7, an annular bulge, or inverted U-shaped 
section, of relatively thin walled silicone rubber is provided between the 
skirt 50 and the head structure 14' in lieu of flange 30 of FIG. 1. This 
reduces the transmitted wall pressure (TWP) at the point of entry to skirt 
50. It also provides a cushion 52 having an upwardly convex arcuate radial 
cross-section projecting upstreamwardly from the transverse portion of the 
flange 30'. The skirt 50 and cushion 52 are made much thinner than the 
remainder of the head structure 14' in order to be very pliant. When a 
teat is inserted into the tube 12', the skirt 50 presses against and seals 
with the upper part of the teat adjacent the cow's udder. The annular 
cushion 52 is dimensioned to cushion against the udder where it joins the 
teat, with cushion 52 serving to further minimize irritation. The 
pliability of the skirt 50 and cushion 52 aid in minimizing irritation to 
the teat and udder. 
The embodiment shown in FIG. 4 also illustrates an alternate construction 
of the downstream end of the inflation with two annular beads 16' and 60 
spaced axially of the length of the inflation 12'. The spaced beads are 
adapted to fit respectively upstream and downstream of the lower end of 
the teat cup 15, as seen in FIG. 4, to more positively retain the 
inflation in the cup. 
In both of the embodiments illustrated in FIGS. 1 and 4 the head structures 
14 and 14' are shaped to minimize breakage resulting from being stepped 
upon by a cow. Accordingly, the head structure 14 is integrally connected 
by an annular throat section 100 formed by an outwardly flared upstream 
end of the wall 12. The upper edge of rigid cup 15 abuts against the 
underside of the annular throat section 100. The lower part of head 
structure 14 comprises generally a cylindrically symmetric outer retaining 
skirt 101 that is integral with and extends generally downwardly and 
inwardly from the outer edge of throat section 100. The skirt 101 extends 
from the throat section 100. The lower extremity of the skirt 101 is 
spaced from the exterior wall 13 of the tube 12 and shaped to fit over and 
seal against the wall of cup 15 below the upper end of the wall. 
The exterior of the skirt 101 has a cylindrical section 102 that extends 
downwardly from a shoulder 103 that is spaced outwardly from the throat 
100. An inwardly tapered conical frustum 104 extends downwardly and 
inwardly from the cylindrical section 102 to the lower extremity of skirt 
10. 
A conical frustum attachment section 106 is formed integrally with the ring 
100 and the upper edge of the cylindrical section 102. The outer face 107 
of the attachment section 106 extends upwardly of and inclines inwardly 
from the shoulder 103 to provide an uppermost circular edge 108 coaxial 
with the tube 12, but with a larger diameter than the tube 12. The 
horizontal, annular flange 30 is formed integrally with and extends 
inwardly from the attachment section 106. The upper face 109 of flange 30 
extends inwardly from the circular edge 108. 
The sections 102, 104 and 106 are made relatively thick, as compared with 
inflation section 12 to provide strength. 
The inflation 110 illustrated in FIGS. 5-6 embodies features derived from 
the present invention that are particularly protective of a cow's teat and 
udder. A tube 112 is topped by a head structure 114 of the inflation 110. 
The head structure 114 comprises generally a cylindrically symmetric outer 
skirt 115 that is integral with, and extends generally downwardly from, an 
outwardly flaring annular throat section 116 defining the upper portion of 
the tube 112. The head structure is the same as that depicted in FIG. 4 
except that typical useful dimensions are indicated. Although described 
below in terms including dimensions of a desirable embodiment of the head 
structure, these dimensions are not intended to be limiting of the 
invention. 
Accordingly, the exterior of the skirt 115 has a right cylindrical section 
118 having a diameter of 2.25" and a height of 0.360" centered on the 
vertical axis 120 of the inflation. An inwardly tapered conical lower 
frustum 122 descends at an angle of 35.degree. from the vertical to a 
distance of 0.406" below the bottom of cylindrical section 118. The bottom 
of lower frustum 122 corners inwardly to a horizontal section 124 having a 
width of 0.078." Horizontal section 124 corners at its innermost edge to 
an inner frustum 126 rising outwardly at a 26.degree. angle from the 
vertical axis. Inner frustum 126 connects smoothly to the bottom of a 
circular arc 128 that joins smoothly to the lower surface of the throat 
section 116. The circular arc 128 is of radius 0.118" and is centered on a 
horizontal circular line of centers 130. The line of centers 130 has a 
diameter of 1.624" and is spaced 0.157" below the top of the cylindrical 
section 118. 
The inner surfaces 126, 128 are adapted to be positioned in sealing fashion 
over the upper edge of the teat cup 15. 
An inwardly tapered upper conical frustum 132 rises above the upper edge of 
the cylinder 118 at an angle of 30.degree. from the vertical. The top of 
upper conical frustum 132 rounds over, with a radius of 0.125", to a flat 
annular horizontal surface 134 which is spaced 0.406" above the top of 
circular 118. 
Upper conical frustum 132 and surface 134 are the outer boundaries of a 
section that has as its inner boundary a circular arc surface 136 of 
radius 0.094" centered on a horizontal circular line of centers 138. 
Circular line of centers 138 has a diameter of 1.500" and is spaced 0.157" 
below the flat annular surface 134. The circular arc surface extends 
outwardly, starting from vertically above line of centers 138 and 
extending to below the line of centers 138, where the surface flares 
smoothly into the outwardly flared inner surface of the tube 112. The 
horizontal flat annular surface 134 and the upper extremity of circular 
arc surface 136 thereby define the outward portion of a generally inwardly 
directed annular lip 140 having a thickness of about 0.063". 
Annular lip 140 is shaped to include an annular, upwardly extending cushion 
portion 142 which continues inwardly from the flat surface 134 to a 
downwardly directed teat receiving annular flange 144, each having a 
thickness of about 0.063". The cushion portion 142 is bounded by 
semicircles 146, 148 centered on, and above, a horizontal circular line of 
centers 150. Circular line of centers 150 has a 1.219" diameter and lies 
in the plane defined by the flat horizontal surface 134. The semicircles 
146, 148 have respective radii 0.125" and 0.063". The semicircles 146, 148 
are faired smoothly outwardly into the respective surfaces 134, 136 by 
arcs 152, 154 having respective radii 0.031" and 0.063". 
The inner end of semicircle 146 joins smoothly to a 90.degree. concave arc 
156 of radius 0.031" and then to a 90.degree. convex arc 158 of radius 
0.125" to flares into the outer surface of flange 144. Correspondingly, 
the outer end of semicircle 148 joins smoothly to an approximately 
90.degree. convex arc 160 of radius 0.063" and then to a 90.degree. 
concave arc 162 of radius 0.063" to fair into the inner surface of the 
teat receiving flange 144. Flange 144 extends to a distance of 0.157" 
below horizontal surface 134 where it terminates in a convex semicircular 
tip 164 having a diameter of 0.063". 
It may be seen from the description that annular lip 140 comprises an 
inner, cantilevered portion of the head structure 114, which is very 
flexible inwardly of the cushion portion 142. Accordingly, when the 
inflation 110 is removed from a teat, the teat will pull the end 164 of 
downwardly directed teat receiving flange 144 in an upward direction. As a 
result, the annular flange 144 will flex upward to form an upward directed 
annular rim, as illustrated in FIG. 6. The annular rim will permit easy 
withdrawal of the inflation from the teat because the end 164 is no longer 
positioned to resist withdrawal of the teat. 
The tube below the head structure 114 may comprise a tapered portion 166 
and a thickened straight portion 168. The tapered portion tapers inwardly 
in the down-going direction with an internal taper angle of 1.degree. and 
extends to 5.469" below the upper edge of the right cylindrical section 
118 where it is terminated by an inward step 170. An integral, external 
annular bead 172 surrounds the tube at a height of 3.703" above the step 
170. Two axially spaced integral, external annular beads 174, 176 surround 
the tube externally to the step 170 to provide means for tensioning 
against the lower end of the teat cup. The lower bead 174 is positioned 
approximately at step level, the upper bead being spaced about 0.25" 
higher. Each of the beads 172, 174, 176 is of approximately semicircular 
cross-section protruding externally from the outer surface of tube 112, 
the semicircular cross-section having a radius of about 0.070". The 
semicircular cross-section of bead 172 is centered on a circular line of 
centers 178 that is 1.00" in diameter. The semicircular cross-section of 
beads 174 and 176 are centered on respective circular lines of centers 
180, 182 that are 0.875" in diameter. 
The tube wall between the beads 172, 176 is of a substantially uniform 
thickness of about 0.094" to provide a very flexible tube wall. The 
thickness increases with height above the bead 172, the outer periphery of 
the tube wall flaring outward with an initial angle of 2.degree. from the 
vertical. 
It will, of course, be understood that modification of the present 
invention in its various aspects will be apparent to those skilled in the 
art, some being apparent only after study and others being a matter of 
routine design. Further, the use of the particular materials and shapes 
described herein are not necessary features of the present invention. As 
such the scope of the invention should not be limited by the particular 
embodiment and specific construction herein described, but should be 
defined only by the appended claims and equivalents thereof.