U.S. patent number 3,787,147 [Application Number 05/318,088] was granted by the patent office on 1974-01-22 for two-stage air-hydraulic booster.
This patent grant is currently assigned to Owatonna Tool Company. Invention is credited to Clarence L. Kostelecky, Samuel B. McClocklin.
United States Patent |
3,787,147 |
McClocklin , et al. |
January 22, 1974 |
TWO-STAGE AIR-HYDRAULIC BOOSTER
Abstract
A two-stage air-hydraulic booster having two pumping chambers,
with one being a relatively large-volume, low-pressure chamber and
the other a relatively small-volume, high-pressure chamber and with
both chambers being formed, in part, by pumping structure carried
by an air-operated piston. The ratio of the area of the
air-operated piston to the area of the hydraulic cylinder for the
large-volume, low-pressure chamber is relatively low whereby a
large volume of fluid per inch of stroke is delivered to the system
while the ratio of the area of the air-operated piston to the area
of the high-pressure, small-volume chamber is high to deliver a
small volume of fluid per inch of stroke of the air-operated
piston. The structure provides for minimal consumption of operating
air in both advancing the movable air-operated piston in a pumping
stroke and in return of the air-operated piston to an initial
position.
Inventors: |
McClocklin; Samuel B.
(Owatonna, MN), Kostelecky; Clarence L. (Owatonna, MN) |
Assignee: |
Owatonna Tool Company
(Owatonna, MN)
|
Family
ID: |
23236598 |
Appl.
No.: |
05/318,088 |
Filed: |
December 26, 1972 |
Current U.S.
Class: |
417/302; 60/578;
417/401; 60/547.1; 417/393 |
Current CPC
Class: |
F04B
9/12 (20130101); F04B 49/18 (20130101) |
Current International
Class: |
F04B
9/00 (20060101); F04B 9/12 (20060101); F04B
49/18 (20060101); F04b 017/00 (); F04b 035/00 ();
F15b 007/00 () |
Field of
Search: |
;60/547,560,574,575,576,577,578
;417/302,62,225,392,393,398,401 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Geoghegan; Edgar W.
Assistant Examiner: Zupcic; A. M.
Attorney, Agent or Firm: Hofgren, Wegner, Allen, Stellman
& McCord
Claims
We claim:
1. A two-stage air-hydraulic booster having a cylinder with a
movable piston therein, means including a first member on said
piston defining a large-volume low-pressure hydraulic chamber,
means including a second member on said piston defining a
small-volume high-pressure hydraulic chamber, air passage means for
selectively directing air against a face of said movable piston to
cause movement thereof from an initial position and force hydraulic
fluid from said chambers, and second air passage means for
selectively directing air against one of said members to return
said movable piston to said initial position.
2. A booster as defined in claim 1 wherein said first member is an
annular sleeve extending from a face of the piston opposite said
first mentioned face thereof, and said air for returning the piston
to said initial position is directed against the exposed end of
said annular sleeve.
3. A booster as defined in claim 2 wherein said means defining the
small-volume chamber includes a block with a bore receiving the
second member on the piston, said annular member being fitted onto
said block to define said large-volume chamber therebetween, and a
second bore in said block defining a hydraulic flow passage to said
large-volume chamber.
4. A booster as defined in claim 3 including a hydraulic fluid
reservoir, said reservoir being annular and having an inner wall
surrounding said annular sleeve whereby said inner wall and said
block define a chamber to receive said annular sleeve and the
return air for returning the piston to said initial position.
5. A booster as defined in claim 1 including a control circuit with
means for selectively directing air under pressure to either said
face of the piston or against said first member, and said second
air passage means including a quick exhaust valve responsive to air
pressure caused by movement of said piston toward said initial
position to connect said second air passage means to exhaust.
6. A booster as defined in claim 5 wherein said quick exhaust valve
is responsive to the supply of air under pressure to said piston
face to block said connection to exhaust.
7. A booster as defined in claim 5 wherein said control circuit
includes a shiftable valve for selectively connecting said
large-volume chamber to a hydraulic reservoir, and an air operated
control piston associated with said valve whereby said valve shifts
when the force thereagainst exceeds the force against said air
operated control piston, and an air pressure regulator for
controlling the pressure of the air acting against said air
operated control piston.
8. A two-stage air-hydraulic booster having a body with a cylinder
with a movable piston therein, a cylindrical block extending from
one end of the body toward said piston, an annular housing fitted
to said end of the body to define a hydraulic reservoir and with
the inner wall of said housing being spaced from the cylindrical
block, an annular sleeve extending from one face of said piston and
into the space between said block and said annular housing whereby
a large-volume low-pressure chamber is defined within said sleeve,
a first bore in said block and a plunger in said bore and extending
from said one face of said movable piston whereby a small-volume
high-pressure chamber is defined in said first bore, means for
selectively directing air under pressure to said cylinder and
against a face of said piston opposite said one face to move said
piston from an initial position and reduce the size of said
chambers, and means for selectively directing air under pressure
against an exposed end of said annular sleeve to return said
movable piston to said initial position.
9. A booster as defined in claim 8 wherein said block has a second
bore communicating with said large-volume low-pressure chamber.
10. A booster as defined in claim 8 including a hydraulic valve for
connecting said large-volume chamber to either an outlet or
reservoir, and means providing for shift of said valve to complete
the connection to said reservoir when a predetermined pressure
exists in said large-volume chamber.
11. A booster as defined in claim 10 including a control circuit
having air and hydraulic components including said hydraulic valve,
and said shifting means includes an air-operated control piston
which acts to yieldably hold said valve against shifting.
12. A booster as defined in claim 11 including a pilot-operated
check valve for preventing return flow to the reservoir upon loss
of pressure air in said control circuit.
13. A booster as defined in claim 8 including an air exhaust
passage connected to a passage leading to said cylinder and a quick
exhaust valve positioned at the entrance to said exhaust passage
and responsive to air under pressure being supplied to said
cylinder to close the exhaust passage and responsive to reverse air
flow as said movable piston returns to initial position to open
said exhaust passage for quick return of said movable piston.
14. A booster as defined in claim 8 including a control circuit
with air-operated components, a device operated by hydraulic fluid
supplied from said chambers, and means for preventing return of
hydraulic fluid to said chambers upon loss of pressure air in the
control circuit.
15. A two-stage booster having a body with a cylinder with a
movable piston therein, a cylindrical block extending from one end
of the body toward said piston, an annular housing fitted to said
end of the body to define a hydraulic reservoir and with the inner
wall of said housing being spaced from the cylindrical block, an
annular sleeve extending from one face of said piston and into the
space between said block and said annular housing whereby a
large-volume low-pressure chamber is defined within said sleeve, a
first bore in said block and a plunger in said bore and extending
from said one face of said movable piston whereby a small-volume
high-pressure chamber is defined in said first bore, means for
selectively directing control fluid under pressure to said cylinder
and against a face of said piston opposite said one face to move
said piston from an initial position and reduce the size of said
chambers, and means for selectively directing control fluid under
pressure against an exposed end of said annular sleeve to return
said movable piston to said initial position.
Description
BACKGROUND OF THE INVENTION
This invention pertains to a two-stage air-hydraulic booster
wherein an air-operated piston has structure associated therewith
which coacts with additional elements to form high and low pressure
pumping chambers and pumping elements which deliver a relatively
large volume of low-pressure hydraulic fluid and, when a certain
pressure is reached, deliver a smaller volume of high-pressure
hydraulic fluid.
The assignee of this application is the owner of Schoenleben U.S.
Pat. No. 3,625,006 which discloses a two-stage hydraulic booster.
In the structure of this Patent, the air-operated piston is mounted
in an air cylinder with opposite planar faces of the piston being
subject alternately to air pressure for advance and retraction of
the air-operated piston and the pumping structure associated
therewith. Hydraulic boosters of this type require almost as much
air in returning the air-operated piston to initial position as
required in advancing the air-operated piston.
Boosters are shown in Bahniuk U.S. Pat. No. 2,749,845 and in a
pending application owned by the assignee of this application,
namely Schoenleben application, Ser. No. 154,891, filed June 21,
1971. These boosters do not minimize air consumption in return of
the air-operated piston.
SUMMARY
A primary object of the invention disclosed herein is to provide a
two-stage air-hydraulic booster with structure which minimizes air
consumption in providing the desired supply of hydraulic fluid
under low and high pressure and in return of the air-operated
piston back to its initial position.
In the structure disclosed herein, a two-stage air-hydraulic
booster is provided wherein an air-operated piston is movably
mounted within a cylinder and has structure associated therewith
which, in part, provides a low-pressure, high-volume pumping
chamber and a high-pressure, low-volume pumping chamber wherein
maximum hydraulic flow is obtained in a pumping stroke and with a
substantially lesser amount of air being required to return the air
piston to initial position.
More particularly, the air-operated piston has an annular member
movable between the exterior surface of a centrally-positioned
block and the inner wall of a hydraulic fluid reservoir and with
suitable flow passages whereby the annular member and block define
the high-volume, low-pressure chamber which reduces in size as the
air-operated piston advances from its initial position. An exposed
end of the annular member is subjected to pressure air on the
return cycle of the air-operated piston whereby a minimum amount of
air acting against the exposed end of the annular member returns
the air-operated piston and associated structure to an initial
position. This exposed end of the annular member has an area which
is a small fraction of the area of the air-operated piston exposed
to air in advance of the air-operated piston whereby a much smaller
volume of air is required to return the air-operated piston. This
provides a faster return of tne air-operated piston than previously
known and for faster operation of the structure operated by the
hydraulic fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of the two-stage air-hydraulic
booster with the booster assembly and control components shown in
vertical central section and with the air-operated piston and parts
movable therewith shown in initial position;
FIG. 2 is a view, similar to FIG. 1 with parts shown in position
when the booster shifts from the first stage fast approach to the
second stage high pressure stroke; and
FIG. 3 is a view, similar to FIG. 1, showing the parts positioned
for release of the hydraulic pressure and return of the
air-operated piston and associated components to initial
position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The booster assembly has a pair of end plates 10 and 11 secured
together by a plurality of tie rods 12 and capturing therebetween a
cylindrical member 15 having one end fitted into the end plate 11
and the other end fitted onto an end of an annular hydraulic fluid
reservoir 16. The reservoir 16 is generally U-shaped in cross
section and has a cylindrical outer wall 17 and an inner wall 18
with the upper ends of these walls fitted onto a shaped inner face
of the end plate 10. The interior of the reservoir provides for
storage of hydraulic fluid used by the booster. The cylindrical
wall 15 in association with the end plate 11 and the end of the
hydraulic fluid reservoir 16 defines an air chamber in which an
air-operated piston 20 is movably positioned. One face 21 of the
air-operated piston is selectively subject to air under pressure by
air flow through a tubular member 22 extended between the end
plates 10 and 11, with the upper end of the tube 22 communicating
with a passage 23 in the end plate 10. The lower end of the tube 22
communicates with a passage 24 in the end plate 11 leading to a
port in communication with the face 21 of the air-operated
piston.
Means defining a large-volume, low-pressure hydraulic chamber
includes an annular sleeve member 30 extending upwardly from a face
31 of the air piston 20 which surrounds and coacts with a
centrally-positioned block 32 extending inwardly from the end plate
10. Suitable seals, as indicated at 33,34, and 35 are positioned
between the reservoir 16, the block 32 and the inner surface of the
end plate 10.
The low pressure chamber is in flow communication with the exterior
of the booster assembly body through a passage 36 in the block 32
which communicates with a passage 37 in the end plate 10. The
annular member 30 moves within a chamber 40, defined by a space
between the inner wall 18 of the reservoir 16 and the outer surface
of the block 32, with the annular member 30 carrying a seal member
41 engaging the inner wall 18 of the reservoir and the block 32
carrying seals 42 and 43 engageable with the inner surface of the
annular member 30. When pressure air is supplied to the tube 22,
the air is supplied to the face 21 of the air-operated piston 20 to
move the air-operated piston and annular member 30 upwardly to
reduce the size of the low-pressure chamber and direct hydraulic
fluid outwardly through the passage 36 in the block 32.
The small-volume, high-pressure chamber is defined by a chamber 45
in the block 32 with the air-operated piston 20 carrying a plunger
or piston 46 movable within said chamber whereby upward movement of
the air-operated piston 20, as shown in FIG. 1, causes upward
movement of the piston 46 to reduce the size of the chamber 45 and
force hydraulic fluid to flow outwardly of the booster assembly
body through a passage 47 extending through the end plate 10.
The booster assembly body has a second air passage 48 through the
end plate 10 leading to the chamber 40 whereby pressure air may be
directed selectively against the upper exposed end of the annular
member 30 to move the air-operated piston downwardly to the initial
position shown in FIG. 1.
The two-stage air-hydraulic booster is usable for supplying
hydraulic fluid to one or more operating devices. A hydraulic clamp
is shown at 50 as being typical of such an operating device. The
control for supply of hydraulic fluid to the operating device 50
includes an air control circuit and a hydraulic control circuit.
The air control circuit includes a pilot valve 51, an air control
valve 52 and an air pressure regulator 53.
The hydraulic control circuit includes a hydraulic control valve
body 54 having an air piloted release valve, indicated generally at
55, a check valve 56 and an air piloted unloading valve, indicated
generally at 57. The control circuit also includes a pilot-operated
check valve 58.
With the air-operated piston 20 and associated parts in initial
position, as shown in FIG. 1, the pilot valve 51 is positioned, as
shown in FIG. 1, to have a supply of air under pressure in a supply
line 60 flow through a passage 61 to the upper end of a valve bore
in the air control valve 52 and act against the upper end of a
valve spool 62 to urge the valve spool downwardly to the position
which is shown in FIG. 1, against the action of a spring 62a. This
places the air supply from supply line 60 in communication with the
air pressure regulator 53 by connecting passage 60 with a passage
63 leading to the air pressure regulator and air then flows through
a passage 64 into pilot chambers for the release valve 55 and the
unloading valve 57. The pilot section for the release valve 55
includes a piston 65 having a stem 66 extending to a point adjacent
a poppet valve member 67 urged to the right, as viewed in FIG. 1,
against a seat by a spring 68. Air from the passage 64, by flow
through a passage 69 in the valve body 54, acts against the
left-hand face of the piston 65 to urge the pilot piston to the
right and the pin 66 away from engagement with the release valve
member 67. Pressure air also acts against a right-hand face of a
pilot piston 71 of the unloading valve, as viewed in FIG. 1, to
urge the pilot piston 71 to the left and against a poppet valve
member 72 to urge the poppet valve member against its seat.
With the control valve member 62 positioned as shown in FIG. 1, the
upper side of the operating device 50 is connected to an exhaust
air line through a conduit 75 which extends through the check valve
58 and into the valve body 54. A passage in valve body 54 connects
the conduit 75 to a conduit 76 extending to the body of the air
control valve 52 with exhaust air then flowing through the body of
valve 52 and through a passage 77 to the exhaust line 78. Air under
pressure in passage 64, which acts upon the pilot 71 of the
unloading valve, also communicates with the air tube 22 through a
pair of passages 80,81 leading to the passage 23 in communication
with the tube 22. Interposed between passages 80 and 81 is a
diaphragm-type quick exhaust valve 83 which, as shown in FIG. 1,
permits communication between passages 80 and 81 and blocks
communication to the exhaust line 78.
In operation, air under pressure directed to the face 21 of the
air-operated piston 20 causes movement of the air-operated piston,
the annular member 30, and the plunger 46. This causes flow of
hydraulic fluid through the passage 36 and also from the chamber
45. These flows combine and reach a conduit 90 communicating with a
piston 91 in the operating device 50. The flow from the
small-volume chamber 45 is through the passage 47 and through a
passage 92 in the valve body 54 with the flow being around the
check valve 56 and the release valve 55 and then through the check
valve 58. The flow from the large-volume chamber passes through the
passage 36 and to a passage 95 in the valve body 54 with the flow
being around the stem of the unloading valve 72 and through the
check valve 56 which is away from its seat due to the pressure of
the hydraulic fluid acting thereagainst. The flow joins the flow
from the chamber 45 downstream of the check valve 56.
During this operation, the chamber 40 is connected to exhaust by
the passage 48 communicating with an air passage 100 in the valve
body 54 which connects with the passage 76.
In this operation, a large volume of low-pressure hydraulic fluid
is delivered to one or more operating devices 50 with the
switchover to a high-pressure, low-volume operation being
controlled by the action of the pilot-operated unloading valve 57.
The changeover pressure is determined by the pressure of the air
supply as well as the ratio of the area of the pilot piston 71 to
the area of the poppet valve member 72. When the pressure of the
hydraulic fluid is sufficient to cause movement of the poppet valve
member 72 against the action of the pilot piston 71, the unloading
valve poppet member 72 moves to the position shown in FIG. 2
whereby fluid flow from the large-volume chamber flows past the
poppet valve member 72 to a passage 110 which connects to a passage
111 in the end plate 10 having a connecting tube 112 extending down
into the reservoir. This releases the pressure in the large-volume
chamber so that the air pressure acting against the face 21 of the
air-operated piston 20 is now acting to move the piston 46 to pump
high-pressure fluid from the chamber 45. This fluid acts against an
end of the poppet valve member 72 to hold the unloading valve open.
The hydraulic pressure continues to build until the pressure
thereof acting against an end of the piston 46 is balanced by the
force of the air acting against the piston face 21. The maximum
pressure reached is controlled by controlling the air pressure
provided to the system by the setting of the air pressure regulator
53.
The position of the booster assembly and control components at the
time of shifting to the low-volume, high-pressure condition is
shown in FIG. 2 wherein the flow from the large-volume chamber is
through bore 36 and past the poppet valve member 72 of the
unloading valve with flow then through passages 110 and 111 and
tube 112 to the reservoir, as shown by the arrows. High pressure
fluid from chamber 45 flows to the operating device 50 with the
check valve 56 and the poppet valve member 67 of the release valve
55 being on their seats to prevent flow of high pressure fluid to
the passages leading to reservoir. As seen in FIG. 2, continued
upward movement of the air-operated piston 20 will cause the piston
46 to deliver fluid at a high pressure from the chamber 45 with the
ratio between the area of the air-operated piston 20 and the piston
46 being relatively large to create the high pressure.
As stated above, the final pressure capable of being applied to the
operating device 50 is controlled by the setting of the air
pressure by the air pressure regulator 53.
The pilot-operated check valve 58 is provided as a safety control
to maintain hydraulic pressure at the operating device 50 in the
event that air pressure is lost in the control circuit. The
pilot-operated check valve has a body 115 through which the
passages 75 and 90 extend. These passages intersect a central bore.
A poppet-type check valve 116 is normally urged against a seat 117
by a spring 118 to block hydraulic flow through the passage 90. The
poppet valve member 116 has an internal seat which is normally
closed by a small ball 120, urged toward its seat by the spring
118. An actuating plunger 121 for the small ball 120 is loosely
mounted in a flow passage 122 in poppet valve member 116 and
extends outwardly from an end thereof.
An air-operated piston 130 is also mounted in the bore of the body
115 and engages an actuating rod 131. The air-operated piston and
the actuating rod are both urged to the right, as viewed in FIG. 1,
by a spring 132.
In the first stage operation, shown in FIG. 1, and the second stage
operation, shown in FIG. 2, hydraulic pressure maintains the poppet
valve member 116 away from its seat 117 to permit hydraulic flow to
the operating device 50. When the required pressure is reached and
hydraulic flow stops, the valve member 116 and the small ball 120
are seated by the spring 118 and hydraulic pressure is maintained
if there is a loss of pressure air.
When it is desired to release the pressure on the operating device
50, the pilot valve 51 is moved to the position shown in FIG. 3 to
exhaust pressure air from the air control valve 52 through an
exhaust port 220 whereby the spring 62a moves the valve spool 62 of
the air control valve to its upper position, as viewed in the
Figure. This connects passage 64 to the exhaust line 78 whereby
pressure air previously acting on the right-hand face of the
control piston 71 of the unloading valve and on the left-hand face
of the control piston 65 of the release valve 55 is released.
Passage 80 at the upstream side of the quick exhaust valve 83 is
also connected to exhaust through the passage 64. This permits air
under pressure beneath the air-operated piston 20 to quickly pass
to exhaust 78 by upward movement through the tube 22 and to the
right of the quick exhaust valve, as shown in FIG. 3. Release of
the air pressure from the underside of air-operated piston 20 also
releases the hydraulic pressure, since there is no longer any force
acting against the high pressure piston 46.
Pressure air from the air supply 60 passes through the air control
valve 52 to the line 76 and through line 75 to move the piston 91
of the operating device 50 downwardly. If the operating devices 50
have spring return cylinders, then the port in check valve 58 from
which passage 75 extends can be capped and passage 75 not used.
Pressure air in passage 76 is also directed to the right-hand face
of the control piston 65 of the release valve by communication
therewith through a passage 225 which shifts the control piston and
the stem 66 thereof toward the left, as viewed in FIG. 3, to move
the poppet valve member 67 off its seat to open the valve and
permit return flow of hydraulic fluid to the reservoir by
communication with passage 110.
Return flow of hydraulic fluid to the reservoir additionally
requires opening of the pilot-operated check valve 58. This is
accomplished by the pressure air in passage 75 extending through
the pilot-operated check valve 58. This pressure air acts on the
right-hand end of the air-operated piston 130 to move the actuating
rod 131 to the left to engage and move the plunger 121 to unseat
the small ball 120. Hydraulic flow from the operating device 50 can
flow to the left-hand end of poppet check valve 116 through an
annular passage between the outer diameter of the poppet check
valve 116 and the bore in the valve body 115. The fluid then flows
through the low passage 122 in the valve member 116.
When the pressure of the hydraulic fluid decreases by flow through
flow passage 122 to the point where the force exerted by the
air-operated piston 130 exceeds the force of the hydraulic pressure
against the left-hand end of the poppet check valve 116, the latter
valve is lifted from its seat, allowing free flow of hydraulic
fluid from the operating device 50 and as shown in FIG. 3.
Pressure air in passage 76 is also supplied to passage 100 to
direct pressure air into the chamber 40 where it acts upon the
upper exposed end of the annular member 30 to force the
air-operated piston 20 downwardly along with the parts connected
thereto. During this downward movement to the initial position of
FIG. 1, hydraulic fluid flows from the operating device 50 past the
open poppet valve member 67 of the release valve, as previously
described, and also directly to chamber 45 through the passage 92.
The return flow past the open poppet valve member 67 may flow to
the lower pressure chamber through passage 36 by flow to passage 95
and past the poppet valve member 72 of the unloading valve which is
off its seat, as shown in FIG. 3. The large-volume chamber may also
receive flow through the passage 110 by movement of a check valve
230 off its seat to connect passage 110 with a space 231 at the end
of the block 32 which opens to the passage 36. At the same time,
hydraulic fluid, which was unloaded to the reservoir during the
high pressure stroke, is returned to the large-volume chamber by
being drawn past the check valve 230.
With the structure disclosed herein, it is possible to have a
two-stage air-hydraulic booster with a control providing for an
adjustable setting of the ultimate pressure and which automatically
controls the setting at which the shift from low to high pressure
will occur. Additionally, a minimum amount of air is used in
operating the air-operated piston of the booster. The minimal use
of air in return of the air-operated piston to initial position
results in faster action.
* * * * *