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Abstract:

A piston rod and cylinder seal device includes a cylinder defining a
piston chamber extending between first and second cylinder heads. The
second cylinder head has a spud receiving bore, a pressure passage
communicating with the spud receiving bore, and a bore supply/vent
passage. A first piston is disposed in the piston chamber. A piston rod
is connected to the piston, the piston rod having a piston rod spud
extending beyond the first piston and including a blind shaft receiving
bore. A second piston slidably disposed in the blind shaft receiving bore
has a seal member connected thereto. A contact member connected to the
second cylinder head in the spud receiving bore has a central passage
extending therethrough in communication with the bore supply/vent
passage. The seal member when contacting the contact member acts to seal
the central passage.

Claims:

1. A piston rod and cylinder seal device, comprising: a cylinder creating
a piston chamber extending between opposed first and second cylinder
heads; a first piston slidably disposed in the piston chamber, the first
piston having a piston rod connected to the first piston; a piston rod
spud extending from the piston rod, the piston rod spud having a blind
bore and a second piston slidably received in the blind bore; and a
contact member connected to the second cylinder head, the contact member
having a central passage extending therethrough, a seal member disposed
in the second piston when contacting the contact member acting to seal
the central passage.

2. The piston rod and cylinder seal device of claim 1, wherein the second
cylinder head includes a spud receiving bore having the contact member
disposed therein, a pressure passage communicating with the spud
receiving bore, and a bore supply/vent passage communicating with the
central passage of the contact member.

3. The piston rod and cylinder seal device of claim 2, wherein when the
piston contacts the second cylinder head the piston rod spud is fully
received in the spud receiving bore and pressurized air in the bore
supply/vent passage communicating with the contact member is isolated by
the seal member from the pressure passage communicating with the spud
receiving bore.

4. The piston rod and cylinder seal device of claim 1, further including
a shaft bore having a threaded bore wall created in the second cylinder
head receiving a threaded portion of the contact member.

5. The piston rod and cylinder seal device of claim 1, further including
a biasing member positioned in the blind bore acting to continuously bias
the second piston toward the contact member.

6. The piston rod and cylinder seal device of claim 5, wherein the second
piston includes opposed first and second counterbores, the seal member
received in the first counterbore, and the biasing member partially
received in the second counterbore.

7. The piston rod and cylinder seal device of claim 5, wherein: the
second cylinder head includes a spud receiving bore having the contact
member disposed therein; and following contact between the contact member
and the seal member, continued displacement of the piston rod spud into
the spud receiving bore displaces the second piston into the blind bore
in a second piston contraction direction thereby compressing the biasing
member.

8. The piston rod and cylinder seal device of claim 1, wherein the
contact member includes a dome shaped curved contact end facing the seal
member.

9. The piston rod and cylinder seal device of claim 8, wherein the curved
contact end includes a circular apex acting to create a circular contact
seal when in direct contact with the seal member.

10. The piston rod and cylinder seal device of claim 1, further including
a retention ring assembly positioned in a ring slot created in the piston
rod spud, the second piston contacting the retention ring assembly in a
fully extended position of the second piston.

11. A piston rod and cylinder seal device, comprising: a cylinder
defining a piston chamber extending between opposed first and second
cylinder heads, the second cylinder head having a spud receiving bore, a
pressure passage communicating with the spud receiving bore, and a bore
supply/vent passage; a first piston slidably disposed in the piston
chamber; a piston rod connected to the piston, the piston rod having a
piston rod spud extending beyond the first piston and including a blind
shaft receiving bore; a second piston slidably disposed in the blind
shaft receiving bore, the second piston having a seal member connected
thereto; and a contact member connected to the second cylinder head in
the spud receiving bore, the contact member having a central passage
extending therethrough in communication with the bore supply/vent
passage, the seal member when contacting the contact member acting to
seal the central passage.

12. The piston rod and cylinder seal device of claim 11, further
including a biasing member positioned in the blind shaft receiving bore
acting to continuously bias the second piston in a second piston
extension direction toward the contact member.

13. The piston rod and cylinder seal device of claim 12, wherein
following contact between the contact member and the seal member
continued displacement of the first piston in a piston drive direction
causes the second piston to displace in an opposite second piston
contraction direction.

14. The piston rod and cylinder seal device of claim 11, wherein the
piston reciprocates in opposed piston return and drive directions in the
piston chamber, the piston rod spud is slidably received in the spud
receiving bore when the piston is displaced in the piston drive direction
to position the seal member in contact with the contact member thereby
preventing pressurized air in the bore supply/vent passage from entering
the spud receiving bore.

15. The piston rod and cylinder seal device of claim 11, further
including a cushion seal ring connected to the second cylinder head
creating an annular passage between the cushion seal ring and the piston
rod spud when the piston rod spud is received in the spud receiving bore.

16. The piston rod and cylinder seal device of claim 15, further
including a portion of the piston chamber defined between the piston and
the second cylinder wall, wherein the portion of the piston chamber is in
fluid communication with a flow path including the annular passage, the
spud receiving bore and the pressure passage prior to contact of the seal
member with the contact member.

17. The piston rod and cylinder seal device of claim 11, wherein the
second cylinder head further includes a first switch having a first
conductive biasing member extending into the piston chamber, the first
piston contacting the first conductive biasing member when the first
piston contacts the second cylinder head.

18. The piston rod and cylinder seal device of claim 17, wherein the
first cylinder head includes a second switch having a second conductive
biasing member extending into the piston chamber, the first piston
contacting the second conductive biasing member when the first piston
contacts the first cylinder head.

19. A crust breaker system, comprising: a piston rod and cylinder seal
device, including: a cylinder creating a piston chamber extending between
opposed first and second cylinder heads, the second cylinder head
including a pressure passage in communication with a spud receiving bore
and a bore supply/vent passage also in communication with the spud
receiving bore, a first piston slidably disposed in the piston chamber,
the first piston having a piston rod connected to the first piston; a
piston rod spud extending from the piston rod, the piston rod spud having
a blind bore and a second piston slidably received in the blind bore; and
a contact member connected to the second cylinder head in the spud
receiving bore, the contact member having a central passage extending
therethrough providing communication between the bore supply/vent passage
and the spud receiving bore, the contact member when contacted by a seal
member disposed in the second piston acting to seal the central passage;
and a pneumatic valve system having: a first control valve; and a valve
position control line connecting the first control valve to the pressure
passage.

20. The crust breaker system of claim 19, further including a crust
breaking rod connected to the piston rod opposite to the piston rod spud.

21. The crust breaker system of claim 20, wherein the pneumatic valve
system further includes a solenoid operated valve having a solenoid, the
solenoid energized or de-energized by a signal generated when the crust
breaking rod contacts a bath having a voltage completing a circuit
including a conductive seal of the piston and the cylinder.

22. The crust breaker system of claim 19, wherein the pressure passage
and the valve position control line are vented to atmosphere when the
piston rod spud is slidingly received in the spud receiving bore.

23. The crust breaker system of claim 19, wherein the pressure passage
and the valve position control line are both pressurized when the piston
rod spud is positioned outside of the spud receiving bore such that the
seal member is not in contact with the contact member.

24. The crust breaker system of claim 19, wherein the contact member
includes tool engagement flats.

25. The crust breaker system of claim 19, wherein the pneumatic valve
system further includes: a second control valve; a first pressure source
connected to a first portion of the piston chamber through the first
control valve; a second pressure source connected to a second portion of
the piston chamber through the second control valve; and a third pressure
source connected to the pressure transfer line.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 13/159,061 filed on Jun. 13, 2011. The entire
disclosure of the above application is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to seal devices used in pneumatic
control systems for operating metal processing baths.

BACKGROUND

[0003] This section provides background information related to the present
disclosure which is not necessarily prior art.

[0004] Known systems used to control operations of metal processing baths
such as for aluminum processing can include pneumatic valves and piping
used to drive a crust breaking tool to create an aperture by breaking
through the hardened upper crust layer formed on the bath. The crust
breaking tool is intended to open the aperture to permit addition of
additional alumina material to the molten bath of aluminum. When creation
of the aperture has been confirmed, pressurized air directs the crust
breaking tool to retract from the crust layer. The drawbacks of such
systems include the large volumes of pressurized air which are used to
control a normal crust breaking operation, and particularly when crust
material forms on the crust breaking tool such that bath detection cannot
occur, and/or when the crust breaking tool cannot penetrate the crust
layer.

[0005] In these situations, the crust breaking tool can remain in the bath
for an undesirable length of time which can damage the crust breaking
tool, or render the detection system inoperative. Also in these
situations, the subsequent feeding of new alumina material into the bath
can be hindered, or the system may be unable to identify how many feed
events have occurred, thus leading to out-of-range conditions in the
bath. A further drawback of known control systems is the large volume of
high pressure air required significantly increases operating costs of the
system due to the size and volume of high pressure air system
requirements, power consumption and cost, the operating time of
pumps/compressors, and the number of air compressors and air dryers
required for operation.

SUMMARY

[0006] This section provides a general summary of the disclosure, and is
not a comprehensive disclosure of its full scope or all of its features.

[0007] According to several embodiments a piston rod and cylinder seal
device includes a cylinder creating a piston chamber extending between
opposed first and second cylinder heads. A first piston is slidably
disposed in the piston chamber. The first piston has a piston rod
connected to the first piston. A piston rod spud extends from the piston
rod, the piston rod spud having a blind bore and a second piston slidably
received in the blind bore. A contact member connected to the second
cylinder head has a central passage extending therethrough. The contact
member when contacted by a seal member disposed in the second piston acts
to seal the central passage.

[0008] According to other embodiments, a piston rod and cylinder seal
device includes a cylinder defining a piston chamber extending between
opposed first and second cylinder heads. The second cylinder head has a
spud receiving bore, a pressure passage communicating with the spud
receiving bore, and a bore supply/vent passage. A first piston is
slidably disposed in the piston chamber. A piston rod connected to the
piston has a piston rod spud extending beyond the first piston and having
a blind shaft receiving bore. A second piston slidably disposed in the
blind shaft has a seal member connected thereto. A contact member is
connected to the second cylinder head in the spud receiving bore. The
contact member has a central passage extending therethrough in
communication with the bore supply/vent passage. The seal member when
contacting the contact member acts to seal the central passage.

[0009] According to further embodiments, a crust breaker system includes a
piston rod and cylinder seal device, including a cylinder creating a
piston chamber extending between opposed first and second cylinder heads.
The second cylinder head includes a pressure passage in communication
with a spud receiving bore and a bore supply/vent passage also in
communication with the spud receiving bore. A first piston slidably
disposed in the piston chamber has a piston rod connected to the first
piston. A piston rod spud extending from the piston rod has a blind bore
and a second piston slidably received in the blind bore. A contact member
connected to the second cylinder head in the spud receiving bore has a
central passage extending therethrough providing communication between
the bore supply/vent passage and the spud receiving bore. The contact
member when contacted by a seal member disposed in the second piston acts
to seal the central passage. A pneumatic valve system includes a first
control valve and a valve position control line connecting the first
control valve to the pressure passage.

[0010] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples in
this summary are intended for purposes of illustration only and are not
intended to limit the scope of the present disclosure.

DRAWINGS

[0011] The drawings described herein are for illustrative purposes only of
selected embodiments and not all possible implementations, and are not
intended to limit the scope of the present disclosure.

[0012]FIG. 1 is an end elevational view of an aluminum bath crust breaker
device having a piston rod and cylinder seal device of the present
disclosure;

[0013]FIG. 2 is a cross sectional front elevational view taken at section
2 of FIG. 1;

[0014]FIG. 3 is a cross sectional front elevational view taken at area 3
of FIG. 2;

[0015]FIG. 4 is a cross sectional front elevational view taken at area 4
of FIG. 2;

[0016]FIG. 5 is a cross sectional rear elevational view taken at section
5 of FIG. 1;

[0017]FIG. 6 is a cross sectional front elevational view taken at area 6
of FIG. 5;

[0018]FIG. 7 is a system diagram of a crust breaking system having the
piston rod and cylinder sealing device of FIG. 1;

[0019]FIG. 8 is a system diagram of the crust breaking system of FIG. 8
showing the crust breaker rod after breaking through the crust layer;

[0020]FIG. 9 is a cross sectional front elevational view modified from
the view taken at area 4 of FIG. 2 to include a further aspect of a
piston rod and cylinder seal device;

[0021]FIG. 10 is a cross sectional front elevational view modified from
FIG. 9 to show the piston in contact with the second cylinder wall;

[0022] FIG. 11 is a cross sectional front elevational view of area 11 of
FIG. 9;

[0023]FIG. 12 is a cross sectional front elevational view modified from
FIG. 9 to show the point of contact between the seal member and the
contact member;

[0024]FIG. 13 is a front perspective view of the contact member of FIG.
9;

[0025]FIG. 14 is a front elevational view of the contact member of FIG.
13;

[0026]FIG. 15 is a cross sectional side elevational view taken at section
15 of FIG. 14; and

[0027] FIG. 16 is a top front perspective view of the second piston of the
present disclosure.

[0028] Corresponding reference numerals indicate corresponding parts
throughout the several views of the drawings. For simplification, not all
parts are shown in all views of the drawings.

DETAILED DESCRIPTION

[0029] Example embodiments will now be described more fully with reference
to the accompanying drawings.

[0030] Referring to FIG. 1, a piston rod and cylinder sealing device 10
includes a cylinder 12 enclosed by a first cylinder head 14 defining a
first end of cylinder 12. A control portion 16 having one or more sensor
connectors 18 extending therefrom is also provided with piston rod and
cylinder sealing device 10.

[0031] Referring to FIG. 2, cylinder 12 defines a piston chamber 20 and
further includes a second cylinder head 22 creating a second end of
cylinder 12. Control portion 16 can be connected to second cylinder head
22. A piston 24 is slidably disposed within piston chamber 20 such that
piston chamber 20 is divided into a first portion 20a on a first side of
piston 24 and a second portion 20b on a second side of piston 24.

[0032] Piston 24 is connected to a piston rod 26 which can include a crust
breaker rod 28 connected to piston rod 26, or forming a free end of
piston rod 26. Piston rod 26 extends through first cylinder head 14 and
is slidably disposed using a rod bearing/seal 30 such that pressure
within piston chamber 20 is contained by rod bearing/seal 30. At an
opposite end of piston rod 26 is provided a piston rod spud 32 which is
slidingly disposed in a spud receiving bore 34 when the piston 24
contacts second cylinder head 22.

[0033] A hollow tubular shaft 36 is connected to second cylinder head 22
and is slidably received within piston rod spud 32 when piston rod spud
32 slidingly enters spud receiving bore 34. A fluid pressure such as
pressurized air can be introduced through hollow tubular shaft 36 from a
bore supply/vent passage 38 created in second cylinder head 22. A
pressure supply/vent port 40 is also provided with second cylinder head
22. Air pressure supplied at pressure supply/vent port 40 can be directed
into spud receiving bore 34.

[0034] Referring to FIG. 3, piston rod spud 32 includes a blind shaft
receiving bore 42 which is sized having a spud bore diameter "C" adapted
to slidingly receive a shaft diameter "D" of tubular shaft 36. When a
shaft free end 44 of tubular shaft 36 is initially received in shaft
receiving bore 42, the outer perimeter wall defining shaft diameter "D"
contacts a first seal member 46 which is positioned in a seal slot 48 of
piston rod spud 32. Continued displacement of piston rod spud 32 in the
piston return direction "A" provides continuous sealing contact between
tubular shaft 36 and first seal member 46 throughout the length of
tubular shaft 36. Tubular shaft 36 also provides a central passage 50
extending throughout a total length of tubular shaft 36. Central passage
50 therefore communicates with shaft receiving bore 42 of piston rod spud
32, therefore permitting fluid such as compressed air in shaft receiving
bore 42 to displace in the piston return direction "A" as piston rod spud
32 moves in the piston return direction "A". According to several
embodiments, a means for installing tubular shaft 36 is provided such as
the provision of a plurality of wrench engagement flats 52 which are
positioned proximate to shaft free end 44 and within central passage 50.
Wrench engagement flats 52 can be engaged by a tool (not shown) such as a
wrench used to rotate and therefore install tubular shaft 36.

[0035] It is further noted that an annular passage 53 is provided between
piston rod spud 32 and a cushion seal ring 54 which is connected to
second cylinder head 22. A sliding clearance is provided between piston
rod spud 32 and cushion seal ring 54. Cushion seal ring 54 as known in
the art allows pressurized fluid such as pressurized air in second
portion 20b of piston chamber 20 to pass from second portion 20b into
spud receiving bore 34 as the piston 24 and piston rod spud 32 both
travel in the piston return direction "A". During pressurized operation,
annular passage 53 also provides an opposite passageway for compressed or
pressurized air to pass between spud receiving bore 34 and into second
portion 20b.

[0036] Referring to FIG. 4, piston 24 is connected to piston rod 26 using
a piston retention fastener such as a nut 55 which is threadably engaged
with a threaded portion of piston rod 26. Piston retention nut 55 is
threadably engaged until piston retention nut 55 contacts an end face 56
of a nut receiving counter bore 58 created in piston 24. A width or
thickness of piston retention nut 55 is therefore substantially received
within nut receiving counter bore 58. Piston 24 further includes a
conductive seal 60 which is retained about a perimeter wall of piston 24
and slidingly contacts a cylinder inner wall 62 of cylinder 12 at any
sliding position of piston 24. As piston 24 moves in either of the piston
return direction "A" or piston drive direction "B", electrical contact is
therefore maintained between cylinder 12, conductive seal 60, piston 24
and piston rod 26. The use of conductive seal 60 therefore obviates the
need for a secondary connection between piston rod 26 and cylinder 12.

[0037] To displace piston 24 within piston chamber 20, a pressurized fluid
such as pressurized air is introduced for example into first portion 20a
which acts against a first piston face 64 displacing both piston 24 and
piston rod 26 in the piston return direction "A". This displacement of
piston 24 also co-displaces piston rod spud 32 into spud receiving bore
34. When piston rod spud 32 contacts and is sealingly engaged to tubular
shaft 36 using first seal member 46, any fluid in central passage 50 and
shaft receiving bore 42 is isolated from spud receiving bore 34.
Therefore, as piston 24 continues to move in the piston return direction
"A", fluid, such as pressurized air in second portion 20b of piston
chamber 20, is compressed between a second piston face 66 and a head face
68 of second cylinder head 22. Pressurized air in shaft receiving bore 42
is therefore displaced via a flow path including central passage 50 and
bore supply/vent passage 38. Pressurized air in spud receiving bore 34 is
outwardly displaced via a pressure passage 69 in communication with spud
receiving bore 34.

[0038] Tubular shaft 36 is connected to second cylinder head 22 using a
male threaded end 70 of tubular shaft 36 which is threadably engaged in
second cylinder head 22 in female threads created in a shaft receiving
bore 72. Bore supply/vent passage 38 is open to shaft receiving bore 72
via a connecting passage 74.

[0039] Referring to FIG. 5, piston 24 has been removed for clarity. When
piston rod 26 had been displaced in the piston return direction "A" to
the maximum extent, piston rod spud 32 is completely received within spud
receiving bore 34 and piston retention nut 55 is positioned proximate to
head face 68 of second cylinder head 22. To signal that the piston 24 is
at the returned or first piston contact position, a switch having a first
conductive biasing member 76 is contacted by second piston face 66 of
piston 24, thereby completing an electrical circuit indicating contact by
piston 24. A second switch having a second conductive biasing member 78
extends into piston chamber 20 from a head face 80 of first cylinder head
14. Contact between piston 24 and second conductive biasing member 78
would therefore create a second circuit signifying that piston 24 is at a
piston second contact position with first cylinder head 14.

[0040] Referring to FIG. 6, as previously noted, tubular shaft 36 includes
male threaded end 70 which is threadably engaged with a threaded bore
wall 82 of shaft receiving bore 72. To provide additional sealing
capability, tubular shaft 36 can further include a radially extending
flange 84 which contacts a flange contact face 86 created in second
cylinder head 22 proximate to threaded bore wall 82. A second seal member
88, such as an O-ring or D-ring, can be positioned between flange 84 and
flange contact face 86 to provide additional sealing capability. With
piston rod spud 32 completely extending into spud receiving bore 34, a
clearance can be maintained between a spud end face 90 of piston rod spud
32 and a bore end face 92 of spud receiving bore 34. This clearance
permits physical contact between piston 24 and head face 68 of second
cylinder head 22 as previously described in reference to FIG. 4.

[0041] Referring to FIG. 7 and again to FIGS. 1-6, piston rod and cylinder
sealing device 10 can be used in conjunction with a crust breaker system
94. Crust breaker system 94 can include a pneumatic valve system 96 which
is used to direct pressurized air into second portion 20b of piston
chamber 20 to direct piston 24 in the piston drive direction "B" such
that crust breaker rod 28 creates or maintains an aperture 98 through a
crust layer 100 of an aluminum melt bath 102. Aluminum melt bath 102 is
contained in a bath chamber 104. Aperture 98 is created through crust
layer 100 in order to add additional chemicals such as alumina material
to replenish aluminum melt bath 102.

[0042] Crust breaker system 94 can include a first pressure source 106
which can be aligned by control of a first control valve 108 and a second
control valve 110 to direct pressurized air from first pressure source
106 via a first air supply/vent line 112 into first portion 20a of piston
chamber 20 to hold piston 24 in the piston first contact position shown.
To displace piston 24 in the piston drive direction "B", first and second
control valves 108, 110 can be realigned such that pressurized air from a
second pressure source 114 can be directed through an air delivery/vent
line 116 and a second air supply/vent line 118 into spud receiving bore
34 to act on second piston face 66 while simultaneously first portion 20a
is vented to atmosphere via a path including first air supply/vent line
112 and second control valve 110.

[0043] When piston rod spud 32 is fully received within spud receiving
bore 34, air delivery/vent line 116 and second air supply/vent line 118
are both vented to atmosphere through second control valve 110. A valve
position control line 120 which connects air delivery/vent line 116 to a
first operating side of first control valve 108 is also vented to
atmosphere at this time. Piston chamber 20 is therefore not pressurized
to the full pressure range of first pressure source 106 because the
vented valve position control line 120 directs first control valve 108 to
isolate first pressure source 106 from piston chamber 20. Pressurized air
in a third pressure source 122 maintains this position of first control
valve 108 while maintaining a pressure in a pressure transfer line 124
which is connected to bore supply/vent passage 38 in second cylinder head
22. Pressure in pressure transfer line 124 also pressurizes shaft
receiving bore 42 but does not provide enough force to overcome the air
pressure in first portion 20a of piston chamber 20.

[0044] Pneumatic valve system 96 further includes a solenoid operated
valve 126 which directs pressure from a fourth pressure source 128 to
opposite ends of second control valve 110. By changing the orientation or
position of solenoid operated valve 126, second control valve 110 can be
positioned to pressurize either the first or second portion 20a, 20b of
piston chamber 20. Electronic signals used to coordinate the positioning
of solenoid operated valve 126 as well as feedback signals from contact
between crust breaker rod 28 and aluminum melt bath 102 are received
and/or generated using a control device 129.

[0045] Referring to FIG. 8 and again to FIG. 7, to displace piston 24 in
the piston drive direction "B" and away from the piston first contact
position shown in FIG. 7, second control valve 110 is repositioned using
pressurized air from fourth pressure source 128 after reorienting
solenoid operated valve 126 such that pressurized air from second
pressure source 114 is aligned with air delivery/vent line 116 and second
air supply/vent line 118 to pressurize second portion 20b of piston
chamber 20. Simultaneously, first portion 20a of piston chamber 20 is
vented to atmosphere by a path including first air supply/vent line 112
and second control valve 110. Pressurized air in second air supply/vent
line 118 enters spud receiving bore 34, pushing piston rod spud 32 out of
spud receiving bore 34 and further clearing a path for pressurized air in
pressure transfer line 124 to enter second portion 20b via tubular shaft
36. The combination of these two pressure sources acts on second piston
face 66 of piston 24 to displace piston 24 in the piston drive direction
"B". With pressurized air in second air supply/vent line 118, valve
position control line 120 is also pressurized, thereby repositioning
first control valve 108 to align first pressure source 106 to the supply
port of second control valve 110. The position of second control valve
110 temporarily prohibits pressurized air from first pressure source 106
from entering first portion 20a of piston chamber 20. It is noted that
the pressure in valve position control line 120 together with a biasing
member of first control valve 108 overcome the pressure from third
pressure source 122 acting on an opposite end of first control valve 108.
Therefore, even though pressurized air from third pressure source 122
flows through pressure transfer line 124, the biasing member of first
control valve 108 provides the additional force required to reposition
and hold first control valve 108 in the position shown.

[0046] As second piston face 66 of piston 24 displaces away from a contact
position with first conductive biasing member 76, a first switch 130
having first conductive biasing member 76 connected thereto, opens a
circuit signaling that piston 24 has left the piston first contact
position with head face 68. When first piston face 64 of piston 24 second
conductive biasing member 78, a second switch 132, having second
conductive biasing member 78 connected thereto closes a circuit signaling
that piston 24 is proximate to or has contacted first cylinder head 14,
defining a piston second contact position. These circuit signals are
received in control device 129.

[0047] When crust breaker rod 28 either creates or extends through
aperture 98 of crust layer 100 and enters aluminum melt bath 102, a
voltage V2 of the aluminum melt bath 102 is sensed and conducted via
an electrical path including crust breaker rod 28, piston rod 26, piston
24, conductive seal 60, cylinder 12 to control device 129. When the
voltage V2 of aluminum melt bath 102 is detected at control device
129, a signal is transmitted to reposition solenoid operated valve 126,
which subsequently repositions second control valve 110. This position
change of second control valve 110 isolates pressure from second pressure
source 114 and providing a flow path for pressure from first pressure
source 106 to re-enter first portion 20a of piston chamber 20. Piston 24
will thereafter return in the piston return direction "A" to the piston
first contact position shown in FIG. 7. As piston rod spud 32 engages and
seals against tubular shaft 36 pressurized air in pressure transfer line
124 is isolated from spud receiving bore 34, and second air supply/vent
line 118 is vented to atmosphere, thereby repositioning first control
valve 108. Piston rod spud 32, spud receiving bore 34, and tubular shaft
36 therefore provide the capability of redirecting pressurized air and/or
venting pressurized air such that the position of first control valve 108
can be pneumatically operated and repositioned, eliminating the need for
electronic control of either first or second control valves 108, 110.

[0048] Referring to FIG. 9 and again to FIGS. 1-4, according to additional
aspects a piston rod and cylinder sealing device 150 is modified from
piston rod and cylinder sealing device 10, therefore only the differences
will be further discussed herein. In piston rod and cylinder sealing
device 150 a first piston or piston 24 is connected to a piston rod 152
which is modified to include a piston rod spud 154 having a blind bore
156. Piston rod spud 154 is slidingly disposed in spud receiving bore 34
and is in sliding contact with cushion seal ring 54 as the piston 24
approaches and then contacts second cylinder head 22.

[0049] The hollow tubular shaft 36 of piston rod and cylinder sealing
device 10 is replaced in this embodiment with a hollow threaded contact
member 158 which is threadably connected to second cylinder head 22.
Similar to hollow tubular shaft 36, contact member 158 includes a central
passage 160 which in the piston rod sliding contact condition shown in
FIG. 9 opens into both spud receiving bore 34 and bore supply/vent
passage 38. Contact member 158 includes a curved or conical-shaped
contact end 162 which faces a resilient material seal member 164. Unlike
hollow tubular shaft 36 which slidingly enters spud receiving bore 34 and
creates a sliding external seal about hollow tubular shaft 36, the
contact end 162 directly contacts a planar face 166 of seal member 164 to
create a fluid tight seal, thereby preventing fluid/gas communication
between spud receiving bore 34 and bore supply/vent passage 38, and
further blocking pressurized air in bore supply/vent passage 38 from
exhausting through pressure passage 69. Similar to piston rod and
cylinder sealing device 10, a fluid pressure such as from pressurized air
can be introduced through the central passage 160 of contact member 158
from bore supply/vent passage 38 created in second cylinder head 22.

[0050] With continuing reference to FIGS. 9 and 1-4, seal member 164 is
retained in a first counterbore 168 created in a first end of a second
piston 170 which is slidably disposed in blind bore 156 of piston rod
spud 154. At an opposite, second end of second piston 170, a second
counterbore 172 receives a first end of a biasing member 174 which
continuously biases second piston 170 in a second piston extension
direction "E". According to several aspects, biasing member 174 is a
coiled compression spring. An air displacement passage 176 is created
between first and second counterbores 168, 172. During installation of
seal member 164 into first counterbore 168, air is displaced from behind
seal member 164 through air displacement passage 176 into second
counterbore 172, thereby allowing seal member 164 to fully seat within
first counterbore 168.

[0051] When contact end 162 of contact member 158 is spatially separated
from face 166 of seal member 164 as shown in FIG. 9, a biasing force of
biasing member 174 acts on second piston 170. The biasing force retains
second piston 170 at a fully extended position shown. The fully extended
position is reached when second piston 170 directly contacts a retention
ring assembly 178 which is seated in a ring slot 180 created in an inner
wall of piston rod spud 154. A second end of biasing member 174 directly
contacts a bore end wall 182 of blind bore 156. The second end of biasing
member 174 can also be slidably received in a biasing member bore 184
which is similar in diameter to the diameter of second counterbore 172.
Biasing member bore 184 slidably receives the second end of biasing
member 174, thereby helping to retain the alignment of biasing member 174
with second counterbore 172.

[0052] Referring to FIG. 10 and again to FIGS. 9 and 2-4, first piston 24
and piston rod 152 collectively move in the piston return direction "A",
and piston rod spud 154 displaces into spud receiving bore 34 until face
166 of seal member 164 contacts contact end 162 of contact member 158. A
fluid seal is thereby created between seal member 164 and contact member
158, which seals central passage 160 with respect to both blind bore 156
and portion 20b of piston chamber 20. At this time, second piston 170 is
located at its fully extended position in contact with retention ring
assembly 178, and is held at the fully extended position by the biasing
force of biasing member 174. As previously noted with respect to FIG. 9,
the fluid tight seal created when seal member 164 contacts contact end
162 of contact member 158 thereafter prevents fluid/gas communication
between spud receiving bore 34 and bore supply/vent passage 38, and
further blocks pressurized air in bore supply/vent passage 38 from
exhausting through pressure passage 69.

[0053] Referring to FIG. 11 and again to FIGS. 9-10, after contact between
contact end 162 of contact member 158 and seal member 164 occurs,
continued displacement of piston rod spud 154 and piston 24 in the piston
return direction "A" causes an opposite displacement of second piston 170
within blind bore 156 away from contact with the retention ring assembly
178, in second piston contraction direction "F". Sliding motion of second
piston 170 in the second piston contraction direction "F" compresses
biasing member 174. This increases the biasing force of biasing member
174, which thereafter acts to displace second piston 170 in the second
piston extension direction "E" when piston 24 is again displaced in the
piston drive direction "B". It is noted that second piston extension
direction "E" is parallel to piston return direction "A", and second
piston contraction direction "F" is parallel to piston drive direction
"B".

[0054] The fluid seal created when contact end 162 contacts seal member
164 is continuously and dynamically maintained during the sliding motion
of second piston 170. The curved or conical-shaped geometry of contact
end 162 provides the capability to maintain sealing contact between the
contact end 162 and seal member 164 while minimizing wear of seal member
164. Contact end 162 sealing contact with seal member 164 is maintained
at all sliding locations of second piston 170, thereby also accommodating
limited displacement of piston 24 in a side-to-side direction "G". This
allows for normal side-to-side movement of piston 24 and wear of the
conductive seal 60 without loss of the fluid seal at contact end 162.

[0055] Referring to FIG. 12 and again to FIG. 11, piston chamber portion
20b is again pressurized and piston 24 is shown after displacement in the
piston drive direction "B". Second piston 170 is displaced in the second
piston extension direction "E" back to the fully extended position by the
biasing force of biasing member 174. Because blind bore 156 has a
diameter "H" which is larger than a diameter "J" of biasing member bore
184, to accommodate movement of second piston 170 while maintaining
alignment of biasing member 174, diameter "J" provides a sliding fit for
receiving the second end of biasing member 174. This sliding fit helps
retain biasing member 174 in alignment with second counterbore 172 of
second piston 170. At least one, and according to several aspects a
plurality of, piston air bypass slots 186 (see FIG. 16) are created in an
outer wall of second piston 170 to permit air pressure equalization at
opposite ends of second piston 170 as second piston 170 displaces in
either of the second piston extension or retraction directions "E", "F".
The retention ring assembly 178 can be compressible, such that when
second piston 170 contacts retention ring assembly 178, a portion of the
force of impact is reduced by an elastic compression of retention ring
assembly 178. Elastic compression of retention ring assembly 178 also
creates a partially open slot portion 188 of ring slot 180.

[0056] Similar to piston rod and cylinder sealing device 10, piston rod
and cylinder sealing device 150 also provides annular passage 53 between
piston rod spud 154 and the cushion seal ring 54, which is connected to
second cylinder head 22. Sliding clearance is provided between piston rod
spud 154 and cushion seal ring 54. Cushion seal ring 54 allows
pressurized fluid such as pressurized air in second portion 20b of piston
chamber 20 to pass from second portion 20b into spud receiving bore 34 as
the piston 24 and piston rod spud 154 both travel in the piston return
direction "A". During pressurized operation, annular passage 53 also
provides an opposite passageway for compressed or pressurized air to pass
from spud receiving bore 34 into second portion 20b.

[0057] Referring to FIG. 13, contact member 158 includes a contact member
body 190 which according to several aspects is a metal, however the
material of contact member 158 can also be polymeric or a composition of
materials. Contact member body 190 includes a tool engagement first
portion 192, a threaded second portion 194, and a radially flanged third
portion 196 positioned between the first and second portions. The tool
engagement first portion 192 includes a plurality of tool engagement flat
faces 198 which are provided for engagement by an installation tool such
as a wrench or socket (not shown) to allow the threaded second portion
194 to be rotated and torqued to its installed position shown in FIG. 10.
A conical portion 200 transitions between the tool engagement flat faces
198 and the contact end 162.

[0058] Referring to FIG. 14, a first planar face 202 of flanged third
portion 196 is oriented perpendicular to a longitudinal central axis 203
of contact member 158. This provides for continuous planar contact about
substantially the entire first planar face 202 and the flange contact
face 86 shown and described in reference to FIG. 6. A second planar face
204 of flanged third portion 196 is parallel to but oppositely facing
with respect to first planar face 202. The contact end 162 defines a
substantially dome shape or a conical geometry having a theoretical apex
at its intersection with longitudinal central axis 203. In this view,
three of four tool engagement flat faces 198', 198'', 198''' are visible.
According to other aspects (not shown) either less or more than four tool
engagement flat faces can be provided.

[0059] Referring to FIG. 15 and again to FIGS. 10 and 14, according to
several aspects when contact end 162 is curved or dome shaped as shown in
FIG. 14, the degree of curvature of contact end 162 is established based
on a length of a line or radius 206 which has its origin at a point of
intersection 208 with both longitudinal central axis 203 and with a plane
210 defined by second planar face 204. With reference to FIG. 15, in
another aspect having a conical-shaped contact end 163 in place of
contact end 162, the amount of conical taper of contact end 163 defines
an angle a of approximately 3 degrees with respect to its intersection
with a circular apex 212 located at the intersection of contact end 163
and central passage 160. The conical portion 200 is oriented at an angle
β of approximately 30 degrees with respect to a plane defined by any
of the tool engagement flat faces 198. The geometry of either contact end
162 or contact end 163 creates circular apex 212, which defines a
circular line of contact when contact end 162 or 163 initially contacts
seal member 164. This circular line of contact together with the dome or
conical shape of contact end 162, 163 minimizes the surface area of
contact member 158 required to establish and maintain the fluid seal with
seal member 164, and also permits the longitudinal central axis 203 to be
oriented non-perpendicularly with respect to face 166 of seal member 164
as piston rod spud 154 enters spud receiving bore 34. A non-perpendicular
orientation of longitudinal central axis 203 with respect to face 166 of
seal member 164 can occur with normal side-to-side displacement of piston
24, and/or if normal wear occurs to conductive seal 60, which permits the
piston 24 to angularly shift with respect to the longitudinal axis of
piston rod 152 during travel of piston 24 in either the piston return
direction "A" or the piston drive direction "B". Because a sliding seal
between piston rod spud 154 and contact member 158 is not required or
formed in the embodiment of piston rod and cylinder sealing device 150,
angular or side-to-side shift of piston 24 does not affect the ability to
create the fluid seal for central passage 160.

[0060] Referring to FIG. 16 and again to FIG. 9, second piston 170
includes an intermediate wall 214 separating the first and second
counterbores 168, 172 (only first counterbore 168 is visible in this
view). The air displacement passage 176 is created through intermediate
wall 214. Individual ones of the plurality of piston air bypass slots
186', 186'', 186''', 186'''' are equidistantly separated from successive
ones of the slots and each define a longitudinally extending
concave-shaped slot directed inwardly from an outer perimeter wall 216 of
second piston 170. With outer perimeter wall 216 in sliding contact with
an inner wall of piston rod spud 154 (as viewed in FIG. 9), each of the
piston air bypass slots 186', 186'', 186''', 186'''' permits air flow to
equalize pressure on opposite ends of second piston 170 as second piston
170 slidably displaces in blind bore 156.

[0061] Example embodiments are provided so that this disclosure will be
thorough, and will fully convey the scope to those who are skilled in the
art. Numerous specific details are set forth such as examples of specific
components, devices, and methods, to provide a thorough understanding of
embodiments of the present disclosure. It will be apparent to those
skilled in the art that specific details need not be employed, that
example embodiments may be embodied in many different forms and that
neither should be construed to limit the scope of the disclosure. In some
example embodiments, well-known processes, well-known device structures,
and well-known technologies are not described in detail.

[0062] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be limiting.
As used herein, the singular forms "a," "an," and "the" may be intended
to include the plural forms as well, unless the context clearly indicates
otherwise. The terms "comprises," "comprising," "including," and
"having," are inclusive and therefore specify the presence of stated
features, integers, steps, operations, elements, and/or components, but
do not preclude the presence or addition of one or more other features,
integers, steps, operations, elements, components, and/or groups thereof.
The method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the particular
order discussed or illustrated, unless specifically identified as an
order of performance. It is also to be understood that additional or
alternative steps may be employed.

[0063] When an element or layer is referred to as being "on," "engaged
to," "connected to," or "coupled to" another element or layer, it may be
directly on, engaged, connected or coupled to the other element or layer,
or intervening elements or layers may be present. In contrast, when an
element is referred to as being "directly on," "directly engaged to,"
"directly connected to," or "directly coupled to" another element or
layer, there may be no intervening elements or layers present. Other
words used to describe the relationship between elements should be
interpreted in a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the term
"and/or" includes any and all combinations of one or more of the
associated listed items.

[0064] Although the terms first, second, third, etc. may be used herein to
describe various elements, components, regions, layers and/or sections,
these elements, components, regions, layers and/or sections should not be
limited by these terms. These terms may be only used to distinguish one
element, component, region, layer or section from another region, layer
or section. Terms such as "first," "second," and other numerical terms
when used herein do not imply a sequence or order unless clearly
indicated by the context. Thus, a first element, component, region, layer
or section discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of the
example embodiments.

[0065] Spatially relative terms, such as "inner," "outer," "beneath,"
"below," "lower," "above," "upper," and the like, may be used herein for
ease of description to describe one element or feature's relationship to
another element(s) or feature(s) as illustrated in the figures. Spatially
relative terms may be intended to encompass different orientations of the
device in use or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or features
would then be oriented "above" the other elements or features. Thus, the
example term "below" can encompass both an orientation of above and
below. The device may be otherwise oriented (rotated 90 degrees or at
other orientations) and the spatially relative descriptors used herein
interpreted accordingly.

[0066] The foregoing description of the embodiments has been provided for
purposes of illustration and description. It is not intended to be
exhaustive or to limit the disclosure. Individual elements or features of
a particular embodiment are generally not limited to that particular
embodiment, but, where applicable, are interchangeable and can be used in
a selected embodiment, even if not specifically shown or described. The
same may also be varied in many ways. Such variations are not to be
regarded as a departure from the disclosure, and all such modifications
are intended to be included within the scope of the disclosure.