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Патент USA US3092042

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June 4, 1963
H. A. BENTZINGER
PUMP
Filed Dec. 21. 1960
3,092,032
United States Patent 0
1
3,092,032
PUMP
Harlan A. Bentzinger, Wayland, Mass, assignor to Pre
cision Chemical Pump Corporation, Waltham, Mass,
a corporation of Massachusetts
Filed Dec. 21, 1960, Ser. No. 77,424
2 Claims. (Cl. 103-150)
3,092,032
Patented June 4, 1963
2
rod and the ‘motor usually including a train of reduction
‘gearing. This mechanism is usually mounted in a closed
oil ?lled body through a wall of which the reciprocable
rod projects. The pumping chamber, one wall of which
is formed by the movable diaphragm, is provided with
the usual inlet and outlet openings having conventional
check valves associated therewith for control of the move
ment of ?uid in the desired direction as the pump oper
ates. If desired, the other wall of the pumping chamber
This invention relates to pumps and more particularly
to a novel positive displacement sealed piston pump 10 may be of transparent material to permit inspection
while the pump is operating. These aspects of the pres
especially useful for the accurate pumping of liquids,
ent structure are well known in the art and so require
solutions, and the like at high pressures of upwards of
no further explanation except as [to their association with
250-500 p.s.i.
Sealed pumps of the diaphragm type with the customary
check valves have long been used for supplying a stream 15
of liquid, especially 1a corrosive liquid, at a predetermined
the present invention.
Referring to the drawings, the pump body is shown
at 12 and the reciprocable rod at 14, both being broken
rate because of their simplicity and reliability as well as
because their construction enabled the ready use of non
‘away so ‘as to show only their connection to the pump
sures the pumping accuracy was not as great as desired
tion a pumping member is provided attached to the an
head with which the present invention is concemed. The
pump body 12 at its end portion as shown has the form
metalli-c unreactive materials such as rubber and plastics
as their pumping elements. However, such pumps have 20 of a ring with an annular seating surface 16 perpen
dicular to the ring axis. The vrod 14 lies along the ring
not generally been useful at pressures much in excess of
axis and has a threaded end portion 15.
100 psi. because of the bending and eventual failure of
In accordance with the principles of the present inven
the diaphragm or portion thereof; even at lower pres
especially under conditions of varying pressure. Also, 25 nular body seating surface 16 and to the rod 15. Such
member in essence comprises a rigid annular outer mem<
the rtensioning of the diaphragm by ?exing it, this being
ber 22 positioned against seating surface 16, a rigid cen
most pronounced adjacent ‘the line of support of its outer
tral member 25 positioned within the outer member and
edge, eventually caused failure of the diaphragm in that
an elastomeric material 28 having the characteristics of
region, and this happened much more rapidly at higher
30 an incompressible ?uid interposed by adhesive bonding
pressures.
between the outer cylindrical surface 26 of said central
Accordingly, it is a major object of the present in
member and the opposed parallel inner cylindrical sur
vention to provide a novel positive displacement sealed
face 23 of the outer annular member 22. The circular
piston pump accurate to within 1% under the usual
opening of the outer annular member 22 may be con
wherein the degree of failure is reduced to a surprising 35 sidered to define the total diaphragm area, with the
elastomeric material 28 forming a narrow band within
extent. This has been accomplished by providing, in
it such that the diameter of the rigid central member 25
stead of the usual diaphragm having a relatively thin
is a large proportion of the diameter of said opening.
?exible portion for permitting the necessary pumping
It is also important that the elastorneric material be
movement, a novel sealed piston having rigid inner and
outer portions connected by ‘a relatively radially narrow 40 relatively thick in an axial direction in proportion to
its width in ‘a radial direction so that it will be stressed
but ‘axially wide annular band of an elastomeric material
mainly in shear, a ratio of at least about 2:1 as shown
having the characteristics of an ‘incompressible ?uid, with
pumping conditions, in spite of varying pressures and
in FIGS. 3-5 being preferable for pressures of 250 psi.
such material being adhesively bonded to the closely
spaced generally parallel opposing surfaces of the inner 45 or even more being desirable as pumping pressures are
increased. For example, at pressures of about 500 p.s.i.,
and outer rigid portions, rather than vsimply being clamped
a ratio of 4:1 as shown in FIG. 1 is preferred, while at
in position. ‘By utilizing such novel structure, the elasto
higher pressures higher ratios are required in about the
meric material, rather than being subjected to bending
same proportions. The elastomeric material must be
and tension :forces during pumping operation, is stressed
primarily in shear, ‘and this, in [addition to enabling the 50 bonded between the opposed parallel concentric surfaces
construction of a structure able to resist high pressures,
has the unexpected result of providing greatly improved
diaphragm life especially when subject to chemical at
tack and aging.
Furthermore, the use of but a narrow
23, 26 of the inner and outer members 22, 25 to provide
a uniform cross section throughout its annular ring.
Preferably, the elastomeric material is also bonded to
the working face of the central member 25 and of the an
nular member 22 throughout their entire extent as at 27
band of deformable material, with the major portion of 55
mainly to aid in protecting the metallic rigid elements
the structure being rigid, provides but a minute volu
from chemical attack by liquids passing through the pump.
metric distortion upon pressure changes and so results
Additionally, the elastorneric working face 27 is provided
in better pumping accuracy.
with an annular ridge 29 adjacent the inner edge of the
For the purpose of more ‘fully explaining the above
and further objects and features of the invention, refer 60 outer member 22 to provide a substantial degree of pre
loading the elastomeric material 28 in compression in the
ence is now made to the following detailed description
direction of application of ?uid pressure, as shown by
of preferred embodiments of the invention, together with
the accompanying drawings, wherein:
the arrow thereat in FIG. 1. Ridge 29 also functions as a
seal. A plurality of holes 21 is provided in the outer
member 22‘ and its working face '27 for attachment to
embodiment of the pump of the invention;
65 body 12 as hereinafter set forth.
‘FIG. 2 is a cross~sectional plan of the pump of FIG. 1;
Outwardly of the pumping member of the invention
and
as described above is provided a pump housing 30. Said
FIGS. 3-5 are partial cross-sections showing in sim
pump housing has a central recess 31 producing with
pli?ed embodiment the operation of a pump of the in
the pumping member a pumping chamber of a diameter
vention.
A pump unit of the type herein shown may comprise 70 generally the same as the inner diameter of the annular
member 22. Suitable inlet and outlet openings 32 are
a small electric motor, a reciprocable rod ‘for operating
provided into said chamber. If desired, housing 30 may
the diaphragm, and operative connections between the
FIG. ‘1 is ‘a cross~sectional elevation of a preferred
3,092,032
3
be of transparent plastic or the like. The housing is also
provided with ‘a plurality of holes 34‘ matching those of
the annular member 22 and suitable threaded holes in
body 12 for receiving bolts 36 to clamp the assembly
together.
The operation of the structure is conventional from
a pumping standpoint but insofar as the present inven
tion is concerned may best be seen by reference to FIGS.
3-5 wherein is shown a simpli?ed embodiment omitting
a working face covering of elastomer. Thus, the ad
vanced piston position is shown in FIG. 3, the midposition
in FIG. 4, and the retracted position in PK]. 5. FJG. 1
shows the midposition with the prccompression shown
by the small arrows under ridge 29.
This latter is a
useful feature in preventing bond separation at higher
pressures, since the shear stress of operation (NUS. 3
and 5) will tend to separate the surfaces along the bonded
surfaces 23, 36.
The selection of a suitable elastomeric ‘material must
be made with care especially as to its deformation and
bonding characteristics, as well as to its resistance to
A.
ing a pump body with an annular seating surface there
around, a piston pumping member having a rigid annular
outer member positioned against said seating surface and
a central opening therewithin, a reciprocable pump rod,
a rigid central member connected to and reciprocable
by said pump rod positioned within the central opening
of said annular member and an elastomeric material hav
ing the characteristics of an incompressible ?uid inter
posed between an outer cylindrical surface of said cen
tral member and an opposed parallel concentric inner sur
face of said annular member with an axial dimension
substantially greater by about the ratio of 2:1 than the
distance between said opposed surfaces and adhesively
bonded to said opposed surfaces to stress said material
primarily in shear during axial movement of said central
member relatively to said annular member and a pump
housing providing with said pumping member a pump
chamber, and fastening means effective to clamp said
pumping member at its annular member between said
housing and said annular seating surface of said pump
body.
2. A pump head for a high pressure pump comprising
chemical attack. Such materials as natural rubber, butyl
a pump body with an annular seating surface therearound,
rubber, buna N, Hypalon, a chloro-sulfonated poly~
a piston pumping member having a rigid annular outer
ethylene and Viton. a copolymer of hcxafluoropropylene
and vinylidene fluoride, made by Du Pont, are typical 25 member positioned against said seating surface and a
central opening therewithin, a reciprocable pump rod, a
examples of satisfactory elasto-mcrs. As for its deforma
rigid central member connected to and reciprocable by
tion, it has been found that relatively high deformation
said pump rod positioned within the central opening of
forces are necessary to resist the high pressures for which
said annular member and an elastomeric material having
the pump of the invention is particularly useful. Thus
with a piston area of about 3 square inches, and hence 30 the characteristics of an incompressible fluid interposed
between an outer cylindrical surface of said central mem
a periphery of about 3 linear inches capable of resisting
ber and an opposed parallel concentric inner surface of
at least 250 p.s.i., the total shear will be about 160 pounds
said annular member with an axial dimension substan
per linear inch across the ring which ‘must be resisted by
tially greater by about the ratio of 2:1 than the distance
the bonding, such force producing a de?ection of about
between said opposed surfaces and extending throughout
0.05 inch forward and back from a neutral position.
the surfaces of said annular member and said central
Minimum bond strength should preferably be at least
double the de?ection force at a desired de?ection and
member, a housing positioned outwardly of said pumping
member, a raised annular ridge formed on said elas
tomerie material and between said housing and said an—
of resisting a force of F p.s.i., with an area A and a ring
of L inches periphery, the minimum bond strength per 40 nular member, said material adhesively bonded at a bond
strength FA/L of at least a value of about 100 pounds
linear inch will be de?ned as FA/L which must be great
per linear inch to said opposed surfaces to stress said
er than about 100 and preferably ‘at least twice that value.
material primarily in shear during minimum axial move
Bond strengths, in brief, must be adequately high to re
ment of said central member relatively to said annular
sist both the static ?uid pressure and the pumping de
member and said housing providing with said pumping
formation which may be calculated for a given high pres
member a pump chamber, and fastening means effective
sure pump.
to clamp said pumping member at its annular member
Bonding of elastomeric materials such as rubbers and
between said housing and said annular seating surface
plastics to rigid materials such as ‘metals, rigid plastics, etc.
of said pump body.
to provide such shear strengths is well known in the art
and hence need not herein be discussed in detail.
References Cited in the ?le of this patent
Thus, it will be seen that the invention provides a
preferably even higher. In ‘general, with a pump capable
novel sealed piston pump having high pressure and other
UNITED STATES PATENTS
characteristics not heretofore available in such pumps.
Various modi?cations of the invention within the spirit
there-of and the scope of the appended claims will be
apparent to those skilled in the art.
I claim:
1. A pump head for a high pressure pump compris
2,712,793
2,741,187
Holm _______________ __ July 12, 1955
Moller ______________ __ Apr. 10. 1956
2,368,132
France ______________ __ Jan. 30, 1945
FOREIGN PATENTS
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