U.S. patent number 3,768,932 [Application Number 05/151,202] was granted by the patent office on 1973-10-30 for automatic double acting differential pump.
This patent grant is currently assigned to Sigma, narodni podnik. Invention is credited to Harald Bartos, Jan Planica, Josef Svercl.
United States Patent |
3,768,932 |
Svercl , et al. |
October 30, 1973 |
AUTOMATIC DOUBLE ACTING DIFFERENTIAL PUMP
Abstract
An automatic, double acting, differential pump having a body
with a cavity, a reciprocable piston in the cavity which divides it
into a first functional pressure space and a pair of second
functional pressure spaces straddling the first space, means for
interconnecting the second spaces as well as intake and outlet
means communicating with them, sealing means dividing the first
space into two portions and intake and outlet means communicating
with the two portions of the first space when the piston is moved
towards either of the second spaces.
Inventors: |
Svercl; Josef (Olomouc,
CS), Bartos; Harald (Cechy pod Kosirem,
CS), Planica; Jan (Olomouc, CS) |
Assignee: |
Sigma, narodni podnik (Olomouc,
CS)
|
Family
ID: |
22537740 |
Appl.
No.: |
05/151,202 |
Filed: |
June 9, 1971 |
Current U.S.
Class: |
417/393; 91/303;
91/345; 417/396; 91/342; 92/183 |
Current CPC
Class: |
F01L
23/00 (20130101); F04B 9/115 (20130101) |
Current International
Class: |
F04B
9/115 (20060101); F01L 23/00 (20060101); F04B
9/00 (20060101); F04b 017/00 (); F04b 035/00 () |
Field of
Search: |
;417/404,396,393
;92/181,182,183,184,185 ;91/303,323,342,345,346,340 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Sher; Richard
Claims
What is claimed:
1. An automatic, double acting fluid operated differential pump
comprising a body having an inner cavity, a reciprocating piston
located in said cavity, said piston having a pair of radially
enlarged ends dividing said cavity into an inner first functional
pressure space and a pair of second functional pressure spaces
straddling said first functional pressure space, valve means
operable for alternatively distributing a pressurized fluid medium
to said second functional pressure spaces, inlet and outlet means
communicating with said valve means for delivering and discharging
said pressurized fluid medium to and from said second functional
pressure spaces, sealing means located between the inner wall of
said body and about said piston, said sealing means dividing said
first functional pressure space into a first and second portion in
which the ends of said piston are located and inlet and outlet
means communicating with each of said first and second portions for
delivering and discharging a second fluid medium to and from each
of said first and second portions, each end of said piston being
provided with two spaced circum-ferential seals defining a groove
located between them, a discharge duct extending through said
piston from each of said grooves to an outlet port located adjacent
the end of the piston opposite to said groove to communicate with
the outlet means in the respective first and second portion of the
first functional pressure space, and a uni-directional valve
located in each duct to permit fluid to flow from said groove only
when said piston is selectively caused to move towards the opposite
one of the pair of second functional pressure spaces.
2. A pump as defined in claim 1, wherein said body includes a
hollow member extending from one of its ends and said valve means
comprises a slide valve located in the cavity of said hollow member
and includes a pull rod having one end disposed in a cavity in the
piston, said cavity in said piston having a pair of opposed ends
selectively engaging said pull rod on movement of said piston, said
slide cooperating with a plurality of ducts forming a distribution
system for said second functional pressure spaces.
3. A pump as defined in claim 2 including spring means arranged at
each end of said cavity in said piston interposed between said pull
rod and the ends of said cavity.
Description
This invention relates to an automatic double acting differential
pump having a low-pressure distribution which co-acts with a
reciprocating piston which limits high and low-pressure functional
spaces inside the cavity of the body and in which suction and
discharge valves are connected to high-pressure spaces of the
pump.
Many presently known automatic differential pumps of the double
acting type which permit the regulation of high pressures are
designed so that the body of the pump consists of three parts. The
first or upper part is usually a low pressure space equipped with a
slide valve. The center or second part is usually a high pressure
space. The third or lower part is usually a low pressure space.
The above arrangement of the differential pump is relatively
intricate and its assembly is complicated.
An object of the invention is to improve and to simplify, while at
the same time meeting the requirements of operational reliability,
the overall design of an automatic, double acting differential
pump.
It is a further object of the present invention to improve sealing
effects between the low and high pressure spaces of the pump.
The present invention overcomes the above problems and eliminates
the disadvantages and drawbacks of known devices, such as failure
of the seals and consequent leakage from one space to another.
Generally an automatic, double acting differential pump in
accordance with the invention comprises a body with a cavity that
is equipped with a reciprocable piston which divides the cavity
into a first functional pressure space that is a high pressure
space and a pair of second functional pressure spaces that are low
pressure spaces and which straddle the first functional pressure
space. Means for interconnecting the second functional pressure
spaces as well as intake and outlet means therefor are also
provided. In addition sealing means located between the inner wall
of the body and the piston divide the first functional pressure
space into two portions which communicate with intake and outlet
means interconnected with them when the piston is selectively
caused to move toward either of the second functional pressure
spaces.
In order to understand the present invention more completely,
reference is directed to the following specification which is to be
taken in conjunction with the accompanying drawing wherein:
FIG. 1 is an elevational view, partially in section, of a pump in
accordance with the invention showing the internal arrangement in
detail and the piston in top dead center position; and
FIG. 2 is an elevational view in section taken across line 2--2 of
FIG. 1.
Referring now more particularly to FIG. 1, a pump in accordance
with the invention comprises a body 1, which is prefereably
cylindrical, as illustrated, although it can have any other
convenient shape, having a head part 2 at its upper end and an
internal cavity 3 closed at its lower end by a cap 6. The upper
part 2 accomodates both a slide valve 21 and ducts 22, 23, and 24
referred to in greater detail below and which form a low pressure
distribution system. A reciprocable piston 4 is contained in the
cavity 3. The piston 4 itself contains a cavity 4' accomodating a
pull-rod 5, the lower part of which bears against a spring 51
seated at the lower end of cavity 4'. Another spring 52 is located
in fixed position attached to a plug 53 seated in the end of the
upper part of the cavity 4' and surrouns pull-rod 5. The pull-rod 5
is connected to a slide valve 21 located in the upper head part 2.
Piston 4 is provided with upper and lower radial enlarged end faces
41 and 42. Between the upper face 41 of the piston and the face 25
of the upper part 2 of the body and between the lower face 42 of
the piston and the cover 6 there are respectively defined low
pressure annular spaces U and L respectively. A high pressure space
is formed axial between the inner faces 41' and 42' of the piston,
the piston being undercut to form the annular space. A seal 7
secured to the body divides the high pressure space m and n
respectively into two parts, making the automatic differential pump
operate as a double acting device.
Suction intake non-return valves 8 and 8' and discharge non-return
valves 9 and 9' are attached externally to the body of the pump at
the point of location of seal 7. Valves 8 and 9 communicate with
the upper high pressure part m while valves 8' and 9' communicate
with the lower high pressure part n. Between the faces 41, and 41',
and 42 and 42' of the piston are seals 10, 10' and 11 and 11'
respectively. Between each pair of these seals at each of the
respective ends of the piston there are radial grooves 43 and 44.
The radial groove 43 between seals 10 and 10' on the upper part of
the piston is connected to a discharge duct 43' which, when the
piston is in its top dead centre position, communicates with the
discharge valve 9'. Between the radial groove 43 and the discharge
duct 43' there is a non return valve 12 formed by a spring biased
ball. At the lower part of the piston 4 between the seals 11 and
11' a radial groove 44 is formed which communicates with a
discharge duct 44' which passes through the piston 4 and leads via
spring biased ball valve 13 into the upper high pressure space u of
the pump cavity 3.
Referring now more particularly to the upper head part 2 of the
body 1,; that part of the body is provided with inlet means 26
(FIG.2) which communicates with a duct 22 leading to the upper face
41 of the piston. The inlet 26 is opened and closed by means of the
slide valve 21 mentioned above. The slide valve 21 comprises a
spool member movable between a series of radially extending ports
by movement of the rod 5. Leading from the slide valve 21 to the
lower low pressure space L is a duct 24 which connects with the
bottom low pressure space L through the body 1. Communicating with
the slide valve 21 is an outlet 27, the outlet being opened and
closed likewise by the slide valve 21. In addition a duct 23
located in upper part 2 of the body leads into outlet 27 and
communicates with the upper lower pressure distributing space u,
carrying ing discharged from that low pressure space U.
The piston is, as previously described provided on both its ends
with a double seal 10 and 10', and 11 and 11' and the gap between
them is connected through the annular grooves 43 and 44 to the
discharge valves 9 and 9'via discharge ducts 43' and 44' over the
respective high pressure spaces. The above arrangement provides
perfect sealing between the high and low pressure spaces in case of
leaking of high pressure medium through the seal 10' or 11' when
applying high pressures.
For example, during the motion of the piston in direction of the
arrow S which results in the discharge of high pressure medium from
the upper high pressure space via the discharge valve 9 as
explained more fully below the high pressure medium tends to leak
between the body 1 of the pump and the piston 4 through the seal
10'. Medium which may pass through the seal 10' enters the radial
groove 43 and because of interconnection of said groove 43 and
non-return ball valve 12 is released due to underpressure formed
and medium is sucked into the lower high pressure space n between
the face 42' and the seal 7 together with the sucking of medium in
through the suction valve 8'. A similar effect results from the
upward motion of piston 4, i.e., contra to arrow S, via annular
groove 44 and duct 43.
The device operates as follows. Pressure fluid, such as oil is
supplied through the inlet means 26 in direction of the arrow A
(FIG.2) being distributed by the slide valve 21 into the duct 22 on
to the face 41 of the piston, pressuring the upper low pressure
space U. The piston then moves in the direction of the arrow S into
the bottom dead centre position creating a vacuum in the lower high
pressure space n, sucking pressure fluid medium through the valve
8' into the lower high pressure space n, while simultaneously
compressing the volume of the lower low pressure space L to cause
the discharging of medium from the bottom low pressure space L via
duct 24 and slide 21 into the outlet means 27. During the downward
motion of piston mentioned there also occurs simultaneous discharge
of high pressure medium from the upper high pressure space m of the
pump through the discharge valve 9 and simultaneous sucking of
pressure fluid medium through the suction non-return valve 8' into
the lower high pressure space between the lower face 42 and the
seal 7 generally indicated by the arrows B'. The piston moves into
the bottom dead centre position until the spring 52 contacts the
end of the pull rod 5 which is connected to the slide valve 21. At
that moment the slide valve 21 changes its position and the
pressure fluid such as oil or any other medium is reversed to be
led through the duct 24 into the bottom low pressure space L, so
that the pressurized fluid impinges on the lower face 42 of the
piston causing the piston to move upward into its top dead centre
position as seen in the Figures. The medium is discharged from the
upper low-pressure space through the duct 23 into piping 27
wherefrom it is led away in the direction of the arrow B. High
pressure medium is discharged from the annular space n through the
discharge non-return valve 9', accompanied by simultaneous suction
of medium, into the upper high pressure space m through the suction
valve 8 between the face 41' and the seal 7 as seen by arrows A'.
After reaching the top dead centre position the function is
repeated.
The automatic differential pump of the invention, because of its
simple design, is easy to assemble from the individual components
into a functional unit and insures, because of the arrangement and
design of the piston and its components, separation of low-pressure
spaces from the high pressure spaces and prevents the pump from
accidental leakage of medium from the high-pressure space into the
low-pressure one which is of great importance in cases where
different media are employed.
* * * * *