U.S. patent number 3,679,332 [Application Number 05/027,330] was granted by the patent office on 1972-07-25 for reciprocating piston pump.
This patent grant is currently assigned to Union Pump Company. Invention is credited to Reinhard A. Yohpe.
United States Patent |
3,679,332 |
Yohpe |
July 25, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
RECIPROCATING PISTON PUMP
Abstract
A reciprocating high-pressure pump assembly is provided, having
a housing, a piston reciprocably mounted in a cylindrical chamber
of the housing, and an outlet port and valve assembly mounted at
the upper part of the housing. A pair of inlet port and valve
assemblies are additionally mounted in the housing, one
substantially coaxially with the piston, and the other
substantially coaxially with the outlet valve, and in a lower
portion of the housing. This structure, because it utilizes two
inlet valve assemblies, permits inlet valves and housings to be
utilized of considerably reduced dimensions, thereby greatly
increasing the trouble-free operating time of the pump without
reducing pumping capacity, and additionally permitting a plurality
of pump assemblies to be mounted side by side in closer
relationship than is possible with prior art pumps.
Inventors: |
Yohpe; Reinhard A. (Battle
Creek, MI) |
Assignee: |
Union Pump Company (Battle
Creek, MI)
|
Family
ID: |
21837088 |
Appl.
No.: |
05/027,330 |
Filed: |
April 10, 1970 |
Current U.S.
Class: |
417/503;
417/570 |
Current CPC
Class: |
F04B
53/164 (20130101); F04B 53/1025 (20130101); F04B
1/00 (20130101) |
Current International
Class: |
F04B
1/00 (20060101); F04B 53/00 (20060101); F04B
53/16 (20060101); F04B 53/10 (20060101); F04b
021/00 () |
Field of
Search: |
;417/454,503,569,570,568 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Claims
I therefore particularly point out and distinctly claim as my
invention:
1. A reciprocating piston pump comprisinG in combination:
a. a housing defining a plurality of interconnecting chambers
including,
1. a cylinder chamber,
2.an outlet valve chamber, and
3. a pair of inlet valve chambers;
b. a piston arranged in said cylinder chamber for reciprocal
movement therein and having its outer end adapted to be operatively
connected to a power source;
c. an outlet valve assembly mounted in said outlet valve
chamber;
d. an inlet valve assembly mounted in each of said inlet valve
chambers both inlet valve assemblies opening and closing at
substantially the same time and cooperating with said outlet valve
assembly;
e. inlet means connected to each of said inlet valve chambers
adapted to supply liquid thereto;
f. outlet means connected to said outlet valve chamber adapted to
receive liquid therefrom; and
g. a common central chamber within said housing, a cylinder chamber
port connecting said cylinder chamber to said common chamber, an
outlet valve chamber port connecting said outlet valve chamber to
said common chamber, and a pair of inlet valve chamber ports
connecting said inlet valve chambers with said common chamber, the
diameters of said cylinder chamber port, said outlet valve chamber
port, and said inlet valve chamber ports being substantially the
same and one of said inlet valve chambers being substantially
coaxially arranged with respect to said cylinder chamber.
2. A reciprocating piston pump comprising in combination:
a. a housing defining a plurality of interconnecting chambers
including,
1. a cylinder chamber,
2. an outlet valve chamber, and
3. a pair of inlet valve chambers;
b. a piston arranged in said cylinder chamber for reciprocal
movement therein and having its outer end adapted to be operatively
connected to a power source;
c. an outlet valve assembly mounted in said outlet valve chamber
and comprising,
1. a valve seat,
2. a valve guide,
3. a valve member movably mounted in said guide, and
4.means biasing said valve member in closed engagement with said
valve seat;
d. an inlet valve assembly mounted in each of said inlet valve
chambers both inlet valve assemblies opening and closing at
substantially the same time and cooperating with said outlet valve
assembly each comprising,
1. a valve seat,
2.a valve guide,
3. a valve member movably mounted in said guide, and
4. means biasing said valve member in closed engagement with said
valve seat;
e. inlet means connected to each of said inlet valve chambers
adapted to supply liquid thereto;
f. outlet means connected to said outlet valve chamber adapted to
receive liquid therefrom; and
g. a common central chamber within said housing, a cylinder chamber
port connecting said cylinder chamber to said common chamber, an
outlet valve chamber port connecting said outlet valve chamber to
said common chamber, and a pair of inlet valve chamber ports
connecting said inlet valve chamber with said common chamber, the
diameter of said cylinder chamber port, said outlet valve chamber
port, and said inlet valve chamber ports being substantially the
same and one of said inlet valve chambers being substantially
coaxially arranged with respect to said cylinder chamber.
3. A reciprocating piston pump according to claim 2, wherein the
other of said inlet valve chambers is coaxially arranged with
respect to said outlet valve chamber, and wherein said latter inlet
valve chamber and said outlet valve chamber are substantially
perpendicularly arranged with respect to said first inlet valve
chamber and said cylinder chamber.
4. A reciprocating piston pump according to claim 2, wherein said
cylinder chamber is contoured to define a stuffing box, said
stuffing box having a sealing lubricant absorbent material
contained therein, and a radial channel provided in said housing to
permit a sealing lubricant to be applied to said absorbent
material.
5. A pump assembly comprising:
I. a plurality of reciprocating piston pumps mounted side by side,
each pump comprising in combination:
a. a housing defining a plurality of interconnecting chambers
including,
1. a cylinder chamber,
2. an outlet valve chamber, and
3. a pair of inlet valve chambers;
b. a piston arranged in each said cylinder chamber for reciprocal
movement therein and having its outer end adapted to be operatively
connected to a power source;
c. an outlet valve assembly mounted in said outlet valve chamber at
the end of each cylinder;
d. an inlet valve assembly mounted in each of said inlet valve
chambers at the end of each cylinder, both inlet valve assemblies
opening and closing at substantially the same time and cooperating
with said outlet valve assembly;
e. the passage through each of said inlet valve assemblies having a
maximum cross-sectional area not substantially larger than the
cross-sectional area of the passage in said outlet valve assembly
whereby each of said pumps has greater resistance to
stress-corrosive fatigue and shock, and said plurality of pumps may
be mounted in a more compact side-by-side relationship.
f. inlet mans connected to each of said inlet valve chambers
adapted to supply liquid thereto; and
g. outlet means adapted to receive liquid from said outlet valve
chamber;
h. one of said inlet valve chambers being substantially coaxially
arranged with respect to said piston;
Ii. a motor and means operatively connecting said motor with the
end of each of said pistons;
Iii. an inlet manifold means connected to each of said inlet means
for supplying liquid thereto; and
Iv. an outlet manifold means connected to each of said outlet means
and adapted to receive liquid therefrom.
6. A pump assembly comprising:
I. a plurality of reciprocating piston pumps mounted side by side,
each pump comprising in combination:
a. a housing defining a plurality of interconnecting chambers
including,
1. a cylinder chamber,
2. an outlet valve chamber, and
3. a pair of inlet valve chambers;
b. a piston arranged in said cylinder chamber for reciprocal
movement therein and having its outer end adapted to be operatively
connected to a power source;
c. an outlet valve assembly mounted in said outlet valve
chamber,
1. a valve seat,
2. a valve guide,
3. a valve member movably mounted in said guide, and
4. means biasing said valve member in closed engagement with said
valve seat;
d. an inlet valve assembly mounted in each of said inlet valve
chambers, both inlet valve assemblies opening and closing at
substantially the same time and cooperating with said outlet valve
assembly, each comprising,
1. a valve seat,
2. a valve guide,
3. a valve member movably mounted in said guide, and
4. means biasing said valve member in closed engagement with said
valve seat;
e. the passage through each of said inlet valve assemblies having a
maximum cross-sectional area not substantially larger than the
cross-sectional area of the passage in said outlet valve assembly
whereby each of said pumps has greater resistance to
stress-corrosive fatigue and shock, and said plurality of pumps may
be mounted in a more compact side by side relationship,
f. inlet means connected to each of said inlet valve chambers
adapted to supply liquid thereto; and
g. outlet means adapted to receive liquid from said outlet valve
chamber;
b. in each pump one of said inlet valve chambers being
substantially coaxially arranged with respect to said piston;
Ii. an inlet manifold means connected to each of said inlet means
for supplying liquid thereto, and
Iii. an inlet manifold means connected to each of said inlet means
for supplying liquid thereto; an
Iv. an outlet mainfold connected to each of said outlet means and
adapted to receive liquid therefrom.
7. A pump assembly according to claim 6 wherein in each pump the
other of said inlet valve chambers is coaxially arranged with
respect to said outlet valve chamber, and wherein said latter inlet
valve chamber and said outlet valve chamber are substantially
perpendicularly arranged with respect to said first inlet valve
chamber and said cylinder chamber.
8. A pump assembly according to claim 6, having in each pump a
central common chamber within said housing, a cylinder chamber port
connecting said cylinder chamber to said common chamber, an outlet
valve chamber port connecting said outlet valve chamber to said
common chamber, and a pair of inlet valve chamber ports connecting
said inlet valve chambers with said common chamber, the diameters
of said cylinder chamber port, said outlet valve chamber port, and
said inlet valve chamber ports being substantially the same.
9. A pump assembly according to claim 6, wherein in each pump said
cylinder chamber is contoured to define a stuffing box, said
stuffing box having a sealing lubricant absorbent material
contained therein, and a radial channel provided in said housing to
permit a sealing lubricant to be supplied to said absorbent
material.
Description
BACKGROUND OF THE INVENTION
This invention relates broadly to liquid pumps, and more
specifically to novel valve positioning and construction for
high-pressure reciprocating piston pumps.
The rapid advance of modern technology has made increasingly
greater demands upon related industrial and commercial fields.
Particularly, the pump industry has been called upon to furnish
pumping equipment for various new applications and even old
applications with more stringent specification demands in many
fields. In some cases existing equipment or equipment utilizing
standard principles can be readily adapted to these applications.
The pumping industry has made important contributions to the oil
industry, for example, in operations known as secondary recovery.
It has proved beneficial to inject salt water into oil wells
permitting what is called "secondary recovery operations" which
increases the oil productivity in the older well fields. The output
pressures required in this operation are generally in the range of
2,000 to 6,000 p.s.i.
Salt water is the liquid usually used in "secondary recovery
operation." Because it is very corrosive, it causes pump damage
generally referred to as stress-corrosive fatigue. This presents
itself as cracks generally forming at intersections of bores or
chambers. Stress-corrosive fatigue has been shown to occur
frequently and cause greater damage as the bore or chamber size
increases. Reciprocating pumps have been used in this area as a
general practice with the single inlet port and the outlet port
being positioned substantially perpendicular to the cylinder wall
and generally aligned 180.degree. from each other. When the pumps
are operated with shock conditions present, the breakdown
possibilities substantially increase. Shock conditions are caused
normally by starvation of liquid to the system and by air inclusion
in the liquid.
Another important use for high-pressure pumps of the type to which
the present invention is devoted is for the pumping of ordinary
water to place it under high pressure for such applications as
hydraulic cleaning.
Another important use for high-pressure pumps is in the homogenizer
field where the materials to be homogenized such as whole milk,
ingredients of salad dressings, et cetera, are mixed where
necessary for uniformity and forced under high pressure through a
homogenizer valve.
The pump structure presently used in the industry for high-pressure
reciprocating liquid pumps does permit a relatively substantial
volumetric clearance of the piston. Because the inlet and outlet
ports are across from each other, the bore of the inlet port is
required to be larger than desirable so that assembly and
manufacturing procedures can be readily accomplished. Because of
this and other reasons, the piston cylinder bore is also required
to be fairly large. All these factors contribute to high cost and
substantial maintenance expense.
In U.S. Pat. No. 3,373,695, an improved pump is disclosed and
claimed in which the input valve is positioned substantially
coaxially with the piston. This structure has resulted in improved
operation. However, because the input valve and its chamber
assembly must necessarily be rather large in order to handle the
entire input demand, there are limited fields of application, as
for example for the pumping of liquids under exceptionally high
pressures, where an improvement in operation, particularly at high
speeds, might be desirable. Additionally, because of the size of
the input valve assembly, when a plurality of pumps are mounted
together in sequential arrangement, they cannot be mounted as close
together as desired.
SUMMARY OF THE INVENTION
Accordingly, among the objects of the present invention is the
provision of a novel high-pressure reciprocable pump so designed as
to be more corrosion stress fatigue resistant.
It is a further object to provide a high-pressure reciprocal pump
arranged to reduce critical stresses to a minimum, thereby
permitting the pump to operate over long periods without
breakdown.
It is a further object to provide a pump of the type described
having a structure which permits small distances between centers of
pistons and cylinder bores associated with each piston, thereby
permitting a plurality of pumps to be arranged in close
side-by-side proximity.
It is a further object to provide a pump which is relatively small
and economical to manufacture and to operate, while still having
high capacity.
It is an additional object to provide a pump which may be operated
at very high speeds without subjecting the pump structure to
excessive shock loadings.
It is a still further object to provide a pump which may be easily
maintained and serviced.
Still further objects and advantages of the invention will appear
as the description proceeds.
To the accomplishment of the foregoing and related ends, the
invention, then, consists of a high-pressure reciprocable pump
having a single outlet valve and a pair of inlet valves, one
mounted substantially coaxially with respect to the operating
piston, and the other mounted substantially perpendicularly to the
piston and substantially coaxially with the outlet valve. The
resulting structure utilizing two inlet valves permits the valves
and their accompanying structures to be made considerably smaller
individually, thereby reducing the surface area subject to
corrosion and shock stress, and permitting a plurality of pumps to
be mounted side-by-side close together for operation by a single
power source.
BRIEF DESCRIPTION OF THE DRAWINGS
In the annexed drawings:
FIG. 1 is a side elevational view illustrating a pump member having
a structure provided with the improvement of the present
invention.
FIG. 2 is a front elevational view, partially broken away, of the
pump unit illustrated in and seen from the right-hand side of FIG.
1; and
FIG. 3 is an enlarged partial sectional view taken at the line
III--III of FIG. 2, looking in the direction of the arrows.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, numeral 10 refers generally to a pump
assembly. The pump assembly 10 has a motor assembly body 11 with a
base 12, a frame member 13 and an end cover 14. A cylinder assembly
15 is connected to the frame member 13 and is part of the pump
assembly 10.
Referring generally to FIGS. 1 and 2, the cylinder assembly 15 is
shown with an inlet pipe 17 connected to an inlet opening 18 of
manifold 19. A portion of the liquid to be moved through the pump
assembly 10 by cylinder assembly 15 enters from inlet pipe 17
through inlet opening 18 and is distributed to the various cylinder
chambers by manifold 19, as will be explained in detail below. A
second inlet assembly is mounted at the bottom of the cylinder
assembly 15 and comprises an inlet pipe 24, an inlet opening 25,
and a manifold 26, FIG. 3. The liquid influent from both inlets
passes from the cylinder chamber, through an outlet valve, to a
discharge manifold 30. The discharge manifold has a cap assembly 31
on one end, and discharges the liquid through pump assembly outlet
member 32 at its opposite end.
Referring to FIG. 3, the fluid is supplied to the cylinder assembly
15 through both manifold 19 and manifold 26. The manifold 19 is
connected to a cap member 35 by capscrews 36. The manifold is
provided with a drainage plug 37. The cap member 35 is connected to
a cylinder block 38 by means of bolts 33. The cylinder block 38
comprises a housing defining four interconnecting chambers, an
outlet valve chamber 70, a pair of inlet valve chambers 71 and 72,
and a cylinder chamber 76. The inlet valve chamber 71 is
substantially coaxially arranged with respect to the cylinder
chamber 76, and the inlet valve chamber 72 is substantially
coaxially arranged with respect to the outlet valve chamber 70, the
inlet valve chamber 72 and outlet valve chamber 70 being
substantially perpendicular to the inlet valve chamber 71 and
cylinder chamber 76.
A common central chamber 69 formed in the housing of the cylinder
block 38 is connected to the outlet valve chamber by an outlet port
75, to the inlet valve chamber 71 by an inlet port 73, to the inlet
valve chamber 72 by an inlet port 74, and to the cylinder chamber
76 by a cylinder chamber port 89. In the preferred embodiment, the
diameters of the cylinder chamber port 89, the inlet ports 73 and
74, and the outlet port 75 are substantially the same, thereby
insuring uniform stress forces at the ports, and additionally
permitting the piston 93 to be removed through the inlet port 73
when the inlet valve is disassembled, as, for example, when the
various pump parts must be cleaned or sterilized frequently after
operation.
The inlet valve chamber 71 has an inlet valve assembly including a
valve seat member 39 positioned below the cap member 35. A seal 40
is provided between the fold 19 and the cap member 35, and a seal
41 is provided between the valve seat member 39 and the cap member
35. A seal 42 is provided between the valve seat member 39 and the
cylinder block 38. These seals are utilized to contain fluid in the
cylinder assembly 15, and are part of a well-developed art. A valve
member 43 is mounted in a guide and locating member 45. The guide
45 is mounted on the valve seat member 39, and guides the valve
member 43 as it moves from open to closed position. The valve
member 43 has a threaded end 44 which is engaged by a nut 46
holding a stop member 47 in contact with a compression spring
48.
The lower inlet valve is similarly constructed in valve chamber 72
and comprises the manifold 26 affixed to a cap member 55 by means
of capscrews 56. A drain plug 57 is provided in the manifold 26.
The cap member 55 is connected to the cylinder block 38 by means of
bolts 58. A valve seat member 59 is positioned between the cap
member 55 and cylinder block 38. A seal 60 is provided between the
manifold 26 and the cap member 55, a seal 61 is provided between
the valve seat 59 and the cap member 55, and a seal 62 is provided
between the valve seat 59 and cylinder block 38. A valve member 63
is movably mounted in a guide and locating member 65, and is
provided with a threaded end 64 engaged by a nut 66 which maintains
a stop member 67 in contact with a compression sprinG 68.
An outlet port 75 is provided at the side of cylinder chamber 76,
and is oriented substantially at a 90.degree. angle from the axis
of valve member 43, and substantially coaxially with valve member
63. Discharge manifold 30 (FIG. 2) is defined by a wall member 77
forming a part of the block 38 and a cover member 78. The cover
member 78 is connected to the wall member 77 by studs 79 and nuts
80 and sealed to the block 38 by a seal 50. A valve member 83 is
movably positioned with its stem 84 in the channel of a valve guide
85 of the valve seat insert 81. A compression spring 86 acts on a
stop member 87 maintaining the valve member in normally sealed
position. The valve member 83 is provided with a stop member 88
which acts with the stop member 87 to limit the full open position
of the valve member 83.
A portion of the cylinder block 38 defines the cylinder chamber 76.
A piston 92 having a plunger end 93 and screw cap 94 is mounted in
the chamber 76 and is adapted to slide therein with reciprocating
motion. The outer end of the piston 92 is adapted to be connected
to a power actuating means. The cylinder chamber 76 is contoured at
its outer end to provide a stuffing box 95 having a packing ring
96, a lantern ring or gland 97, and a gland follower ring 98, which
make sealing contact between the cylinder assembly and the piston
92. The stuffing box rings 96, 97 and 98 are held in place by an
externally threaded gland nut 99, and locking ring 100. A
lubrication supply groove 101 fed by a supply tube 102 and provided
with a threaded opening 103 provides means for supplying a
lubricating sealing medium to the stuffing box gaskets. A
pressurized lubricating fitting 104 and channel 105 provide
lubrication to an annular chamber 106.
When power is suitably applied to the piston 92, it causes the
piston to move back and forth in a reciprocating movement with
respect to cylinder block 38. As the piston 92 is being drawn away
from the valve members, the pressure of the fluid in manifold 19
and manifold 26 causes the valve members 43 and 63 to be withdrawn
from their sealed position, permitting the liquid from both inlets
to move into the cylinder chamber 76. During this time the
compression spring 86 maintains the valve member 83 in its sealed
position. After the piston 92 has reached its maximum retracted
position, it begins to move back toward the valve members 43 and
63, causing the valve members 43 and 63 to move to their sealed
positions with the valve seats 39 and 59, respectively. At this
time the pressure of the liquid in the cylinder chamber 76 causes
the valve member 83 to open, thereby permitting fluid to pass into
the discharge manifold 30. Succeeding reciprocating movement of the
piston causes the cycle to recur.
In a preferred embodiment the diameter of the cylinder chamber or
bore is substantially the same as that of the port of the inlet
valve chamber with which it is substantially coaxial. Moreover, in
this embodiment the part of the other inlet valve chamber should be
substantially the same as the diameter of the port of the outlet
chamber. In fact, it is advantageous to make the cylinder chamber
bore and the inlet and outlet valve ports of substantially the same
diameter. Such structure was impossible in prior art pumps
utilizing a single inlet valve and outlet port without adversely
affecting the pumping capacity and efficiency. The use of smaller
ports and smaller inlet valve chamber bores in the present
invention reduces hydraulic loading in the cylinder block and on
the inlet valve ports, and permits a smaller diameter and lighter
bolting for the flanges 35 and 55 which clamp the inlet valve ports
to the cylinder block.
The smaller inlet valve and inlet valve chamber bore is made
possible by the addition of a second set of inlet valve ports
located at the bottom of the cylinder block and clamped to the
cylinder block in the same manner as those at the front of the
block. In the preferred embodiment the second inlet valve chamber
bore is positioned at right angles with respect to the piston, and
with the inlet valve ports at the front of the cylinder and
communicating with the cylinder bore at right angles thereto. The
required inlet liquid flow to the piston chamber is thus obtained
through two inlet valves and inlet valve chambers which are much
smaller than would be necessary when only one set of inlet valve
ports and one inlet valve chamber were to be utilized, with
consequent reduction of the stresses in the cylinder block which
have often been resulting in cracks and short operating life of the
cylinder block. Consequently, the pump of the present invention may
be operated at extremely high pressures and high speeds without
unduly enlarging the inlet valve passageways.
In the present invention, only one discharge valve per piston is
employed. The discharge valve and valve chamber are also of small
diameter in relation to pump capacity, with the result that the
port and valve chamber communicating with the cylinder bore at
right angles, and the discharge valve chamber bore may be of
relatively small diameter. The use of a discharge valve having a
small diameter may result in relatively high liquid velocity
through the valve seat bore with higher than normal discharge
pressure loss, but this is relatively unimportant as the loss
relative to discharge pressure of a high-pressure pump is extremely
small. The use of such a small bore intersecting the cylinder bore
serves to reduce the stresses at the intersecting points of the
bores, thus reducing danger of failure at these critical
points.
As an illustration of the degree in reduction of inlet valve
chamber diameter which has been made possible by the present use of
dual inlet valves, one inlet valve coaxial with the cylinder, pumps
have been built and placed in service having inlet valve chambers
of 31/8 inch diameter. It was determined that for the same inlet
pressure loss from entrance to inlet valve seat to the clear area
of the inlet chamber, a prior art pump would require an inlet valve
chamber of approximately 53/8 inches in diameter. It has been found
that in service conditions such as involve high-speed operation at
10,000 p.s.i. discharge, pressure pumps of conventional
construction fail very rapidly. In contrast, pumps constructed
according to this invention have been in experimental service for
more than twenty times the average life of pumps of conventional
construction with still no indication of failure.
In the utilization of high pressure pumps, it is common to place a
plurality of pumps side by side and operate the group of pumps by a
single power source such as an electric motor. When such a
structure is utilized it is important that the pumps be placed as
closely together as possible, so that the overall units may be
small. The present structure facilitates such close spacing for
several reasons. Where a single cylinder block is utilized with a
plurality of pistons, the maximum center distance between pistons,
if not otherwise restricted, is dependent upon the inlet valve
chamber diameter and upon the amount of metal required between
adjacent valve chambers for adjacent pistons for the pressures
involved. Thus, as the inlet valve chamber diameter is reduced, the
center distance may be reduced by both the amount of the inlet
valve chamber reduction and the reduced amount of metal required to
supply adequate strength for the smaller diameter. In the case of
individual cylinder blocks for each piston, the same factors apply
except that the amount of metal between the inlet valve chamber and
the sides of the cylinder block must be considered.
A second consideration is that the minimum center distance between
pistons may be limited by the diameter of the closing means
employed, as for example by the diameter of the flange 35 as shown
in FIG. 3. This diameter depends upon the diameters of the bores in
which the inlet valve parts are positioned, the hydraulic loading
on the parts, and the size of the bolts required, all of which are
smaller for the present structure utilizing two inlet valve
structures. The reduced distance between piston centers also
permits a smaller and lower cost cylinder block. Additionally, the
smaller bores require less machining time. Such economies attain
material significance when large pumps are used and more costly
cylinder block material required. The smaller center distance
between pistons permits a smaller and more economical power unit
for driving the pump, and permits the power units to be used which
would normally be insufficient for conventional pumps.
The present structure additionally permits higher pump operating
speeds to be utilized, especially in larger pump sizes, because the
smaller and lighter weight inlet valves have less inertia than
large ones utilized with single inlet valve constructions, and
therefore less shock is produced with increased speed. Such chock
normally increases critical stresses and as a result contributes to
cylinder failure. An additional feature of the present structure is
that maintenance is relatively simple. The pistons may be readily
removed through the cylinder block after the inlet parts are
removed which are coaxially arranged with the cylinder chamber.
Since these valve parts are smaller and lighter in weight, removal
and installation are easier, particularly for large-size pumps.
While but one form of the invention has been shown and described,
other forms within the spirit and scope of the invention will now
be apparent to those skilled in the art. Therefore the embodiments
shown in the drawings are to be considered as merely setting forth
the invention for illustrative purposes, and is not intended to
limit the scope of the invention herein described, shown and
claimed. It is further to be noted that while directional terms
have been used, same are not to be construed as a limitation of the
invention since such use has been availed of to better describe the
invention as used and illustrated in the drawings.
Other modes of applying the principle of my invention may be
employed instead of those explained, change being made as regards
the means herein disclosed, provided those stated by any of the
following claims or their equivalent be employed.
* * * * *