U.S. patent application number 09/729475 was filed with the patent office on 2002-06-06 for three position cylinder.
Invention is credited to Adams, Robert C. JR., Holt, Douglas J..
Application Number | 20020066363 09/729475 |
Document ID | / |
Family ID | 24931207 |
Filed Date | 2002-06-06 |
United States Patent
Application |
20020066363 |
Kind Code |
A1 |
Holt, Douglas J. ; et
al. |
June 6, 2002 |
THREE POSITION CYLINDER
Abstract
A three position cylinder assembly having an outer cylinder
connected between two bases defining a cap end and a head end. A
stationary tubular member is secured to the cap end of the outer
cylinder at a port to provide fluid access into the outer cylinder.
A first and second piston are disposed within the outer cylinder
and have reciprocal movement therein. Each piston is connected to a
rod which is concentric with the tubular member. The head end has
an aperture for receiving the rods for extension beyond the outer
cylinder, the tubular member has a stop at an end and the first
piston and rod have reciprocal movement along the tubular member,
wherein the stop defines a stable mid-position of the cylinder
assembly. The second piston and rod have reciprocal movement along
the first rod between the first piston and head end, wherein the
head end defines a stable fully extended position of the cylinder
assembly.
Inventors: |
Holt, Douglas J.; (Livonia,
MI) ; Adams, Robert C. JR.; (Romeo, MI) |
Correspondence
Address: |
YOUNG & BASILE, P.C.
Suite 624
3001 West Big Beaver Road
Troy
MI
48084
US
|
Family ID: |
24931207 |
Appl. No.: |
09/729475 |
Filed: |
December 4, 2000 |
Current U.S.
Class: |
92/13.1 ;
91/170R |
Current CPC
Class: |
F15B 11/123
20130101 |
Class at
Publication: |
92/13.1 ;
91/170.00R |
International
Class: |
F01B 001/00 |
Claims
What is claimed is:
1. A three position cylinder assembly for movement between a fully
retracted position, a midposition and a fully extended position,
said cylinder assembly comprising of: an outer cylinder connected
between two bases, the first base defining a cap end and the second
base defining a head end; a first piston connect to a first rod; a
second piston connected to a second rod, wherein said first and
second pistons are disposed and have reciprocal movement within the
outer cylinder, said first and second rods extendable beyond the
head end; and a stop means disposed in the outer cylinder for the
first piston, wherein said stop means is spaced from said cap end
and said head end.
2. The three position cylinder assembly of claim 1 further
comprising a stationary tubular member having one end connected to
the cap end of the outer cylinder and having the stop means
disposed on the other end, said first piston having reciprocal
movement along the tubular member.
3. The three position cylinder assembly of claim 1 wherein, said
first rod has an open end distal from the first piston and an
expanded collar connected to the first piston.
4. The three position cylinder assembly of claim 3, wherein said
second piston has reciprocal movement along the first rod.
5. The three position cylinder assembly of claim 1, wherein said
second rod has a closed end distal from the second piston.
6. The three position cylinder assembly of claim 2 wherein said
first piston forms a first fluid chamber on one side of said first
piston and a second fluid chamber on said other side of said first
piston, wherein said tubular member is open to a port at one end
and has a center passageway therethrough, providing a passageway
opening to a third chamber.
7. The three position cylinder assembly of claim 6, further
comprising a second port selectively opened to the first fluid
chamber.
8. The three position cylinder assembly of claim 7, wherein said
second piston has reciprocal movement along the first rod and forms
a fourth fluid chamber on one side of said second piston and the
second fluid chamber on said other side of said first piston.
9. The three position cylinder assembly of claim 8, further
comprising a third port selectively opened to the fourth
chamber.
10. The three position cylinder assembly of claim 9, further
comprising an open access passageway between the second and third
chambers.
11. The three position cylinder assembly of claim 10, further
comprising: first valve means for selectively communicating a fluid
source to the first chamber; second valve means for selectively
communicating a fluid source to the second and fourth chambers; and
third valve means for selectively communicating a fluid source to
the third chamber.
12. A three position cylinder assembly for reciprocal movement
between a fully retracted position, a mid-position, and a fully
extended position, said cylinder assembly comprising: an outer
cylinder housing having a pair of end walls and a pair of movable
concentric cylinder rods, one of said end walls having an aperture
for slidingly receiving said cylinder rods therethrough, each
cylinder rod having a piston connected thereto at one end; a stop
means positioned within the outer cylinder housing, wherein aid
stop means is spaced from said pair of end walls, and wherein a
first piston is movable between one of the end walls and the stop
means and a second piston movable between the first piston and the
other end wall.
13. The three position cylinder assembly of claim 12 further
comprising means for moving the pair of pistons together and means
for moving each of pistons independently.
14. The three position cylinder assembly of claim 13, wherein the
stop means is positioned on one end of a hollow tubular member
fixedly attached to one end wall of the outer cylinder housing,
said one end wall having a fluid access port therethrough and
communicating with said hollow tubular member for expanding one of
the cylinder rods and moving the piston connected thereto.
15. The three position cylinder assembly of claim 14, wherein the
other cylinder rod and the piston connected thereto has reciprocal
movement along the hollow tubular member.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a cylinder having two
piston and rod assemblies and more particularly, a cylinder having
three stable positions of the piston and rod assemblies including a
fully retracted position, a fully extended position, and a
predetermined mid-position.
BACKGROUND OF THE INVENTION
[0002] Pneumatic or hydraulic cylinders are known to be used to
move objects with the movement of the associated piston and rod
assembly. In most instances, it is desirable to move the object
from the position where the piston and rod assembly is fully
retracted to the position where the piston and rod assembly is
fully extended. In addition, it is sometimes necessary to move the
object to a position extension that corresponds with a
predetermined mid-position of the piston and rod assembly. In the
prior art, to accomplish this, it is necessary to provide a tandem
cylinder such that a cap end cylinder has a stroke corresponding to
the mid-position extension and the rod end cylinder has a stroke
corresponding to the cylinder's full stroke length. The cap end
cylinder then moves the piston and rod assembly to the first
mid-point extension before stopping. Pressure applied to the cap
end of the rod end cylinder moves the piston and rod assembly the
remaining length extension to provide the final displacement. As a
result, a tandem cylinder will have a length equal to the length of
a cylinder of the full stroke plus the length of a cylinder of the
mid-position stroke. This configuration can be a disadvantage where
available property around the cylinder and the moveable object is
at a premium.
SUMMARY OF THE INVENTION
[0003] It is the intent of the present invention to address the
aforementioned disadvantage. According to the invention, it is
desired to provide a three position cylinder with two piston and
rod assemblies, wherein the cylinder housing has a length that is
less than the total combined stroke lengths of the piston and rod
assemblies.
[0004] In one aspect of the invention, a three position cylinder
assembly is provided for movement between a fully retracted
position to a mid-position extension and to a fully extended
position. The cylinder assembly has an outer cylinder housing
connected between two bases, the first base defines a cap end of
the cylinder and the second base defines the head end of the
cylinder. The three position cylinder assembly also includes a
first piston connected to a first rod and a second piston connected
to a second rod wherein both the first and second pistons are
disposed within the outer cylinder. The second base has an aperture
therethrough to permit extension of the rods beyond the outer
cylinder housing. A bumper disposed in the outer cylinder defines a
stop means for one of the pistons. The stop means further defines
the mid-position extension of the cylinder assembly.
[0005] In another aspect of the invention, the three position
cylinder assembly further includes a stationary tubular member
connected to one end of the outer cylinder and extending a
predetermined length within the outer cylinder, and wherein the
first piston has reciprocal movement along the outside surface of
the tubular member. The tubular member has a stop means on the free
end.
[0006] In another aspect of the invention, the first rod has an
open end distal from the first piston for providing a fluid
passageway therethrough and an expanded collar connected to the
first piston. The second piston has reciprocal movement along the
first rod.
[0007] In yet another aspect of the invention, the first piston
forms a first fluid chamber on one side and defines a wall for a
second fluid chamber on the other side of the first piston. The
second piston forms a third fluid chamber on one side of the second
piston and defines another wall for the second fluid chamber on the
other side of the second piston.
[0008] Other objects, advantages and applications of the present
invention will become apparent to those skilled in the art when the
following description of the best mode contemplated for practicing
the invention is read in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The description herein makes reference to the accompanying
drawings wherein like reference numerals refer to like parts
throughout the several views, and wherein:
[0010] FIG. 1 is a side elevational view of a three position
cylinder of the prior art;
[0011] FIG. 2 is a side elevational view of a three position
cylinder assembly according to the present invention shown in a
fully retracted position;
[0012] FIG. 3 is a side elevational view of the three position
cylinder assembly of FIG. 2 extended to a mid-position
extension;
[0013] FIG. 4 is a side elevational view of the three position
cylinder assembly of FIG. 2 shown in a fully expanded position;
[0014] FIG. 5 is a schematic diagram of a drive circuit for the
three position cylinder assembly; and
[0015] FIG. 6 is a table setting forth the program controlling
actuation of the various valve operating solenoids of the drive
circuit of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] FIG. 1 shows a typical cylinder of the prior art. The three
position cylinder 100 of the prior art generally includes a tandem
cylinder having a cap end cylinder 110 and a rod end cylinder 112.
The cap end cylinder 110 has a stroke to an intermediate position
and the rod end cylinder 112 has a stroke to the fully extended
position. The cap end cylinder 10 moves the rod 114 to the first
intermediate position before stopping. The addition of pressure to
the cap end of the rod end cylinder 112 moves the rod 114 to the
fully extended position to provide the final end stop displacement.
The cylinder 100 is therefore required to have a length at least
the total length of the rod end cylinder 112 plus the length of the
cap end cylinder 110.
[0017] Referring now to FIGS. 2-4, a three position cylinder
assembly embodying the present invention is shown. The assembly
includes the elongated outer cylinder designated by the numeral 10
forming a circular bore 11 therein. The outer cylinder 10 has a
walled cap end 12 and a partially opened walled head end 14. Ports
16 and 18 are provided in the walled cap end 12 for fluid access to
the interior of outer cylinder 10. Port 18 is centrally located in
the walled cap end 12. A tubular member 20 is sealingly connected
to the port 18 and extends into the interior of the outer cylinder
10. The tubular member 20 is opened at each end to provide a fluid
conduit from port 18 into the interior of the outer cylinder 10.
The length of the tubular member 20 is predetermined to provide the
desired mid-position extension. A mid-position extension stop means
24 is provided on the tubular member 20 at the end 22 distal from
the port 18. The mid-position extension stop means 24 may include
an expansion of the tubular member 20 such as a flange at end 22,
or a boss securely attached to the exterior of the tubular member
20 at end 22.
[0018] A moveable first piston 26 is slidably received on the
tubular member 20. The first piston 26 is moveable between the
walled cap end 12 of the outer cylinder 10 and the mid-position
extension stop means 24 of the tubular member 20. It is preferred
to have a cushioned bumper 28 located inwardly of the mid-position
extension stop means 24 on the tubular member 20 to cushion the end
stroke of piston 26.
[0019] The first piston 26 divides the interior of the outer
cylinder 10 into a first and second chambers, 30 and 32,
respectively. To prevent fluid movement between the first and
second chambers, the first piston 26 will preferably have sealing
elements 36, 38 on the exterior surface of the piston or in
circumferential grooves 40 formed in piston 26. A rod 42 is
securely attached to an outside face 44 of first piston 26, i.e.,
the face 44 exposed to the second chamber 32. The first rod 42 is a
hollow cylindrical member concentric with tubular member 20. The
first rod 42, has an open through bore 54 providing another
passageway for pressurized fluid entering port 18. The first rod 42
has a first end 46, connected to the face 44 of the first piston
26. The first end 46 of rod 42 includes a mid-position retraction
stop means 48. In the preferred embodiment, the mid-position
retraction second stop means includes an external collar or
shoulder 48 along the outside wall of rod 42. An open port 52 is
provided through the shoulder 48 of the first rod 42. The port 52
provides fluid access between the second chamber 32 and the
interior of the first rod 42. The chamber formed by the interior of
rod and the interior of the tubular member 20 is herein referred to
as the third chamber 54.
[0020] A second piston 56 is slidably seated on the first rod 42.
Piston 56 moves within the outer cylinder 10 axially along the
first rod of 42 and between the head end 14 of the outer cylinder
10 and the shoulder 48 of the first rod 42. The second piston 56 is
also disposed between two chambers within the outer cylinder 10. To
also prevent fluid movement between the second and fourth chambers,
the second piston 56 will preferably have sealing elements 36, 38
on the exterior surface of the piston 56 or in circumferential
grooves 40 formed in piston 56. An inside face 58 of the second
piston 56 forms an end wall to the second chamber 32. The outside
face 60 of the second piston 56 forms an end wall to a fourth
chamber 62. A second rod 64, is securely attached to the outside
face 60 of the second piston 56. The second piston rod 64 is
concentric with the first piston rod 42 and the tubular member 20.
The second piston rod 64 has a closed end 66 distal from the second
piston 56. The closed end 66 of rod 64 encapsulates the third
chamber 54.
[0021] The partially opened rod end 14 has a through aperture 70
for slidable disposition of rods 42 and 64 beyond the outer
cylinder 10. A port 68 is located in the rod end 14 and adjacent to
aperture 70 to provide an access for pressurized fluid into the
fourth chamber 62. The ports 16, 18 and 68 are selectively opened
and closed to move the first and second pistons 26 and 56 and their
associated rods 42, 64 respectively. A device can be connected to
the exposed end 74 of the second rod 64 to provide reciprocal
motion of the device by the three position cylinder.
[0022] In operation, pressurized fluid is routed to the individual
ports via solenoids. FIG. 5 shows a schematic of the drive system
for the three position cylinder assembly. In FIG. 5 there is shown
a proportional directional control valve 80 having solenoids 82 and
84 which operate the proportional control valve 80 in a
conventional manner. Specifically, the proportional control valve
80 is adapted to variably connect conduits 86 selectively to
conduits 88 and 90 or to the position as shown in FIG. 5, wherein
the proportional valve 80 is closed and center to prevent
communication between the conduits 86 with conduits 88 or 90.
Conduit 88 communicates with port 18, and conduit 90 communicates
with port 68. Valve 92 having solenoid 94 allows conduit 86 to
connect to conduit 96 which communicates to port 16. Conduit 86 is
connected to a source of pressurized fluid 98.
[0023] The neutral function as indicated in FIG. 5 shows that all
of the valve operating solenoids 82, 84, 94 are in their normal
de-energized state. The negative sign in the table of FIG. 6
indicates a de-energized state of the solenoid. A positive sign in
the table indicates an energized state of the solenoid.
[0024] To cause the three position cylinder to be extended to its
mid-position as shown in FIG. 3, solenoid 94 is energized while
solenoids 82 and 84 remain deenergized. Solenoid 94 will energize
to open and allow the flow from conduit 86 to connect to conduit 96
and thus provide fluid flow into port 16. Pressurized fluid into
port 16 acts against first piston 26 to move along stationary
tubular member 20 until piston 26 encounters the bumper 28 on
mid-position extension stop means 24. The movement of the first
piston 26 also moves its associated rod 42. The shoulder 48 on the
first rod 42 moves the second piston 56 with the movement of the
first piston 26.
[0025] To fully extend the three position cylinder, solenoid 82 is
also energized in addition to solenoid 94. Energizing solenoid 82
shifts valve 80 to connect conduit 86 with conduit 88. With these
fluid connections established, the fluid source supplies fluid
under pressure through conduit 86 to conduit 88 and hence to port
18 of the three position cylinder. Pressurized fluid enters port 18
and flows through the passageways within tubular member 20 and
first rod 42 to act against the closed end 66 of second rod 64. In
addition, a portion of the pressurized fluid passes through
aperture 52 and into the second Chamber 32. Therefore, the
pressurized fluid also acts against the face 58 of the second
piston 56. The fluid pressure against both the closed end 66 and
face 58 facilitates moving the second rod 64 along with the second
piston 56 in the extending direction. The piston 56 and rod 64 are
fully extended when piston 56 encounters the head end 14 of the
outer cylinder 10. The three position cylinder in its fully
extended position is shown in FIG. 4.
[0026] To then retract the three position cylinder to its
mid-position from its fully extended position, solenoid 94 remains
energized and solenoid 84 will also be energized. Energizing
solenoid 84 will shift valve 80 to connect conduit 86 with conduit
90. Pressurized fluid entering conduit 90 will thereby enter port
68 of the three position cylinder. Pressurized air entering port 68
will expand the fourth chamber 62 and move the second piston 56
toward the first piston 26. As the fourth chamber 62 expands, the
second chamber 32 will contract. Open port 52 equalizes the second
and third chambers 32 and 54, respectively, to allow fluid from the
second chamber 32 to return back through port 18 and to atmosphere
through valve 82 and a muffler 99. When retracting to the
mid-position, solenoid 94 remains on. When the three position
cylinder is to be fully retracted, both solenoids 94 and 82 are
de-energized while solenoid 84 remains energized. Once the three
position cylinder is fully retracted, the three position cylinder
is ready to repeat the aforementioned cycle.
[0027] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiments but, on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims, which
scope is to be accorded the broadest interpretation so as to
encompass all such modifications and equivalent structures as is
permitted under the law.
* * * * *