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Claims  |
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I claim:
1. In combination with a chamber having an aperture surrounded by a seat, a
closure member for the aperture, a plurality of clamping devices angularly
spaced about the aperture periphery and actuable selectively to clamp and
to release the closure member, and hinge means at one side of the closure
member pivotally connecting the closure member and the chamber; the
improvement comprising
means associated with the hinge means for allowing limited translational
movement of the closure member away from the seat to equalize pressure in
the chamber,
and means associated with at least one of said clamping devices
approximately opposite the hinge means for obstructing release of that one
clamping device until all clamping devices nearer the hinge means have
been released.
2. Improvement according to claim 1 wherein said obstructing means comprise
abutment means coupled to said one clamping device for positively
separating the closure member from the seat in response to releasing
operation of said one clamping device.
3. Improvement according to claim 1 including
resilient means yieldably urging said limited translational movement of the
closure member.
4. Improvement according to claim 3 wherein said resilient means includes
spring means associated with the hinge means and acting between the
closure member and the chamber.
5. Improvement according to claim 3 wherein said resilient means includes a
resilient sealing gasket between the closure member and the seat.
6. Improvement according to claim 5 wherein the resilience of the gasket is
sufficient, under clamping condition of said one clamping device and
released condition of all clamping devices nearer the hinge means, to lift
the closure member from the seal adjacent the hinge means.
7. Improvement according to claim 1 wherein said hinge means include hinge
pin means on one of said chamber and closure member, and said movement
allowing means comprise an elongated pin receiving aperture on the other
of said chamber and closure member,
the aperture elongation extending perpendicular to said seat through a
first range which corresponds to normal seat variations and also through a
further range for said pressure equalization.
8. Improvement according to claim 1 wherein said closure member includes a
handle at the side opposite to said hinge means, and said improvement
includes release obstructing means associated with each of the clamping
devices which are oppositely adjacent the handle.
9. In combination with a chamber member having an aperture surrounded by a
seat, and a closure member for engaging the seat to seal the aperture, a
plurality of clamping devices angularly spaced about the aperture
periphery and actuable selctively to clamp and to release the closure
member;
pressure equalizing means coupled to at least one of said clamping devices
for positively separating the closure member from the seat in response to
releasing actuation of said one clamping device.
10. Combination according to claim 9 wherein said one clamping device
comprises
a clamp arm,
means pivotally mounting the clamp arm on one of said members for swinging
movement between an idle position clear of the other member and a working
position permitting only limited separation of the closure member from the
seat,
and clamp actuating means operable, in said working position of the clamp
arm, for selectively clamping the closure member to the seat and releasing
the closure member for only limited separation from the seat.
11. Combination according to claim 10 wherein said pressure equalizing
means comprises abutment means coupled to said clamp actuating means for
positively engaging structure fixedly mounted on said other member in
response to releasing operation of said clamp actuating means.
12. Combination according to claim 10 wherein said pressure equalizing
means comprises abutment means coupled to said clamp arm for positively
engaging structure fixedly mounted on said other member in response to
swinging movement of the clamp arm toward idle position.
13. Combination according to claim 10 wherein said clamp arm mounting means
comprise
a cylindrical hub having the clamp arm journaled on its cylindrical
surface,
and means pivotally mounting the hub with respect to said one member on a
pivot axis parallel to the cylindrical axis of the hub and eccentrically
offset therefrom,
and said clamp actuating means comprise
driving means for rotating the hub selectively in clamping and clamp
relieving directions.
14. Combination according to claim 13 wherein said pressure equalizing
means comprise
cam means coupled to said driving means,
and cam follower means mounted on said other member for cooperation with
the cam means in response to movement of the driving means in clamp
relieving direction.
15. Combination according to claim 13 wherein said pressure equalizing
means comprise
cam means mounted on said clamp arm,
and cam follower means mounted on said other member for cooperation with
the cam means in response to said hub rotation in clamp relieving
direction.
16. Combination according to claim 13 wherein said pressure equalizing
means comprise
cam means mounted on said clamp arm,
and cam follower means mounted on said other member for cooperation with
the cam means in response to swinging movement of the clamp arm toward
idle position.
17. Combination according to claim 10 wherein said slamp arm mounting means
comprise
means pivotally mounting the clamp arm on a pivot axis fixed relative to
said one member, and said clamp actuating means comprise
contact structure mounted on the clamp arm for relative longitudinal
movement and adapted, in said working position of the clamp arm, to engage
and clamp other said member in response to movement in one direction and
to relieve said other member in response to movement in the other
direction,
and driving means for moving said contact structure selectively in said
clamping and relieving directions.
18. Combination according to claim 17 wherein said pressure equalizing
means comprise
cam follower means on said other member,
and cam means on the clamp arm for cooperating with the cam follower means
to positively separate the closure member from the seat in response to
operation of said driving means in clamp relieving direction.
19. Combination according to claim 17 wherein said pressure equalizing
means comprise
cam follower means on said other member,
and cam means on the clamp arm for cooperating with the cam follower means
to positively separate the closure member from the seat in response to
swinging movement of the clamp arm toward idle position.
20. Clamping apparatus for a chamber member having an aperture surrounded
by a seat that is engageable by a closure member to seal the aperture,
with a plurality of clamping devices for the closure member; at least one
of said clamping devices comprising
a hub member including a cylindrical hub having a through bore on a pivot
axis parallel to the axis of the hub and eccentrically offset therefrom,
means on one of said chamber and closure members for pivotally supporting
the hub member on said pivot axis for controllable rotation between a
closure clamping position and a closure relieving position,
a clamp arm journaled adjacent one end on said cylindrical hub and
swingable about the hub axis between an idle position and a working
position,
said clamp arm carrying at its other end rigidly mounted hook structure in
position to be free of the other of said chamber and closure members in
idle angular position of the clamp arm, and to be engageable with said
other member in working angular position of the clamp arm,
said eccentric offset being such that, in working position of the clamp
arm, the hook structure clamps the closure member to the seat in clamping
position of the hub, and permits positively limited closure movement away
from the seat in relieving position of the hub.
21. Clamping apparatus according to claim 20 wherein said hub member
comprises a boss formed on a handle arm extending generally radially from
the hub and swingable manually about said pivot axis to shift the hub
between said clamping and relieving positions.
22. Clamping apparatus according to claim 21 wherein the direction of
handle arm movement is such that any friction between said clamp arm and
said hub tends to retain the clamp arm in working angular position as the
handle arm swings from clamping to relieving position.
23. Clamping apparatus according to claim 21 wherein the direction of
handle arm movement away from clamping position is opposite to the
direction of clamp arm movement away from working position, and said
combination includes means for releasably latching the handle arm and the
clamp arm against relative movement away from said respective positions.
24. Clamping apparatus according to claim 21 wherein said hub member
supporting means comprise
plate structures fixedly mounted on said other member in mutually spaced
parallel relation with aligned plate bores,
and a pivot shaft removably insertable in the hub bore and the two plate
bores to pivotally support the hub member between the plates,
the handle arm and the clamp arm having respective axial thicknesses which
substantially fill the space between the plates.
25. Clamping apparatus according to claim 20 wherein said hub member
supporting means comprise
a shaft journaled on said one member and received in said through bore,
means rotatively coupling the shaft and the hub member,
and means coupled to the shaft externally of the clamping device for
driving the shaft to shift the hub member between said clamping and
relieving positions.
26. Clamping apparatus according to claim 25 wherein said shaft is
journaled on two plate structures which are fixedly mounted on said other
member in mutually spaced parallel relation with said hub member
receivable between them, the hub and the clamp arm having respective axial
dimensions each of which substantially fills the space between the plates.
27. Clamping apparatus according to claim 25, wherein said shaft is coupled
to the hub members of a series of axially aligned clamping devices for
simultaneous operation to selectively clamp and release a single closure
member.
28. Clamping apparatus according to claim 20 wherein said aperture opens
downwardly from a tank member, and said combination includes hinge means
for coupling the closure and the tank member at one side of the aperture.
29. The combination of clamping apparatus according to claim 28 and
airslide means at said aperture with air inlet means below the air slide
means for discharge of fluidized granular material from the tank member.
30. Clamping apparatus according to claim 20 wherein said seat faces
outwardly and said hub member supporting means of each clamping device is
positioned within the chamber member inwardly of the closure member for
normal operation from inside the chamber.
31. The combination of clamping apparatus according to claim 30 including
a handle arm coupled to each hub member,
coupling means adjacent the free end of each handle arm,
and at least one aperture in the closure member normally sealed by means
removable from outside the chamber,
the handle arms being positioned, when in closure clamping position, with
said coupling structure accessible by a tool inserted through the closure
member for swinging the handle arms to release the clamping device.
32. Combination according to claim 20 or 31 including means for yieldingly
urging each clamp arm toward said idle position.
33. Clamping apparatus according to claim 20 wherein said through bore on
the handle axis has the form of a channel opening radially outwardly
through the cylindrical surface of said hub,
and said hub member supporting means includes a pivot pin retained in the
channel by tangential contact with the convex journal surface of said
clamp arm.
34. Clamping apparatus according to claim 20 wherein
said hook structure of the clamp arm is engageable with a surface on said
other member which is inclined radially inwardly relative to the arcuate
path of hook movement due to swinging of the clamp arm about said pivot
axis toward said working position,
and said apparatus includes adjustable stop means for variably terminating
such swinging movement to adjust the tightness of clamping of the closure
member to the seat.
35. Clamp structure adapted for mounting between fixedly supported spaced
parallel mounting plates and comprising
handle arm means having adjacent one end two oppositely facing parallel
surfaces with mutually aligned cylindrical bosses projecting from the
respective surfaces, with a through bore parallel to the common axis of
the bosses and eccentrically offset from that axis by a distance such that
the bore is within, or internally tangent to, the cylindrical boss
surfaces,
clamp arm means journaled adjacent one end on said bosses and carrying at
the other end rigidly mounted hook means,
one of said arm means comprising two portions which are approximate mirror
images of each other with the other arm means rotatably received between
them, the resulting assembly having an axial dimension adjacent said bore
to fit between said mounting plates,
and a pivot pin insertable through said bore and through aligned holes in
the mounting plates.
36. Clamp structure according to claim 35 wherein the two portions of said
one arm means have mutually engageable mating surfaces with means for
releasably joining the portions at the mating surfaces to form a rigid
unit.
37. Clamp structure according to claim 35 or 36 wherein said handle arm
means comprises two members with said oppositely facing surfaces facing
each other with aligned bosses projecting toward each other in
substantially abutting relation and forming an effectively unitary journal
bearing for said clamp arm means.
38. Clamp structure according to claim 35 or 36 wherein said clamp arm
means comprises two members which are journaled on respective bosses that
project oppositely from opposite faces of said handle arm means.
39. In combination with a chamber having an aperture surrounded by a seat,
a closure member mounted by hinge means at one side of the aperture, and
clamping means for releasably securing the closure member in sealing
relation to the seat; improved handle means for swinging the closure
member from the seat after release of the clamping means, comprising
bracket means extending generally radially from the closure member opposite
the hinge means and carrying a hand hold,
a recess in the bracket means having a flaring mouth facing toward the
chamber,
and a fixture rigidly mounted on the chamber in position to be received in
the recess as the closure member approaches the seat, and thereby to
center the closure member with respect to the seat.
40. Handle means according to claim 39 including aligned holes in the
fixture and in the bracket means generally parallel to the seat for
receiving a lock pin when the closure member is clamped to the seat.
41. Method of insuring safe release of residual pressure from a pressure
vessel before opening a manway that is normally sealed by a cover clamped
to a peripheral seat by a plurality of angularly spaced clamping devices;
said method comprising
hinging the cover to the vessel at one side by hinge means which permit
limited translational cover movement away from the seat,
providing means associated with at least one clamping device approximately
opposite the hinge means for blocking release of that clamping device
until all other clamping devices are released,
releasing first said other clamping devices, to cause any residual pressure
to lift said one side of the cover the limited distance permitted by the
hinge means and thereby to equalize pressure in the vessel.
then releasing said at least one clamping device and swinging the cover
open about the hinge means. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention has to do generally with quick acting clamping mechanisms
for releasably clamping two members firmly together, and with a novel
eccentric structure that is useful in such mechanisms and for other
purposes.
The invention is especially useful for releasably securing a movable member
to a larger, relatively fixed member or base, as for securing a closure
member over an aperture to seal a container.
Some aspects of the present invention relate especially to problems that
arise when a vessel containing pressurized fluid is opened without first
releasing all of its internal pressure. Under that condition the internal
pressure may blow the closure wide open, damaging the apparatus or
injuring the operator. Accordingly, without implying any necessary
limitation, the invention will be described primarily as it relates to
securing the closure of such vessels.
Clamp structures of the present invention are typically of the general type
including a clamp arm which is pivotally mounted at one end on one of the
members to be secured together, and which can be swung about the pivot
axis between an idle position or range of positions entirely clear of the
other member and a working position or range of positions in which the
clamp arm limits relative movement of the two members. When in working
position the clamp arm prevents complete separation of the two members,
but without necessarily forcibly clamping them together. Actual clamping
is obtained in one conventional type of structure, by shifting a hook
formation along the clamp arm toward the pivot axis, as by cam or
eccentric mechanism. The two members are thereby forced together into firm
contact.
For sealing apertures in large pressure vessels such as tank trucks for
handling pressurized fluids, for example, the closure member is typically
clamped against the outwardly facing aperture rim by a plurality of
individually operable clamping mechanisms distributed around the
periphery. Improved clamping structures of that general type have been
disclosed by the present applicant in his prior U.S. Pat. Nos. 3,269,587,
3,275,187 and 3,292,812. Those patents also describe and claim a variety
of safety devices for insuring release of residual pressure from a
pressure vessel before the closure member can be fully released. That is
typically accomplished in those patented devices by positively blocking
the clamp arm from swinging into idle position until after the closure has
been lifted free of the aperture rim, which may be done manually or by the
pressure itself. Venting action is thereby provided while the clamp arm is
still in working angular position where it positively prevents the closure
from flying open.
BRIEF DESCRIPTION OF THE INVENTION
One aspect of the present invention relates to an alternative manner of
obtaining clamping action of a clamp arm of the described general type,
namely, by shifting the pivot axis, and hence the entire clamp arm,
relative to the member on which the clamp arm is pivotally mounted. The
invention provides particularly suitable eccentric structure for producing
such movement of the pivot axis. That structure is remarkably simple in
design, is inherently rugged and is economical to produce and to maintain.
Moreover, the structure is highly flexible with respect to such factors as
the direction of handle movement and the magnitude and timing of the
eccentric throw.
That aspect of the invention permits a highly compact structure to provide
great mechanical strength in combination with rapid and reliable
operation. The invention thereby solves a vexing problem in sealing
closures on large pressure vessels, a field quite foreign to such
relatively flimsy and complex clamps as that of U.S. Pat. No. 3,301,548,
for example.
The eccentric structures of the invention are capable of securing large
scale closures under a wide variety of conditions. Illustrative examples
are openings at the bottom of pressure vessels and the like, doors between
watertight compartments of ships, and openings in vessels designed to
resist external pressure, such as submarines. In particular, the invention
can provide for normal control of the latter closures from inside the
vessel and for external control under emergency conditions. Also, clamp
structures embodying the eccentrics of the invention can conveniently be
coupled together in linear configurations for simultaneous operation, as
for sealing a hatch cover on a ship, for example.
A further aspect of the invention provides improved apparatus for insuring
that all pressure has escaped from a pressure vessel before the closure
member is fully released. In preferred form of the invention, that is
accomplished in a novel manner which further insures that the escape of
any residual pressure will take place in a direction away from the
operator. The cover for a manway at the top of a pressure vessel is
typically mounted on one side by a hinge, and is provided with a handle on
the other side by which it may be swung open about the hinge pivot after
full release of the clamps spaced about its periphery. The operator
normally works from the handle side of such a cover, and is thus directly
exposed to the blast of escaping fluid if the cover is opened in the usual
way. Such a blast may injure the operator directly, or may blow him off
the tank with risk of injury from the resulting fall.
I have discovered that such hazards can be avoided by constructing the
cover hinge so that it allows the hinge side of the cover to lift directly
from its seat a short but strictly limited distance when the clamps are
released. With such hinge structure, the operator releases the clamps in
such order that one or two clamps opposite the hinge are released last.
Such clamp or clamps are typically adjacent the handle, and will be
referred to for convenience as handle clamps even if no actual handle is
provided. When all clamps except such one or two handle clamps have been
released, the resilience of the compressed gasket has been found to lift
the cover from its seat at the hinge side, allowing any residual pressure
to escape in a direction away from the operator.
A corresponding method is provided for closures sealed by O-rings or the
like, for which the sealed position of the closure is positively defined
by metal-to-metal contact without effective resilience. Under that
condition, the invention preferably provides spring means near the hinge
for yieldingly urging the closure away from its seat. Then, after all
clamps have been released except one or two opposite the hinge the
operator relieves those remaining clamps, releasing the clamping force but
retaining the clamp arms in working angular position. The springs at the
hinge then lift the hinge side of the cover, aided by any internal
pressure, permitting the pressure to escape safely. The cover cannot fly
open because its movement is strictly limited by the hinge structure on
one side and by the clamp arm or arms which are still in working position
on the other side. Incorporation of spring means in or near the hinge is
also useful in closures sealed by resilient gaskets in order to supplement
the above described action of that resilience.
The invention further provides useful mechanism for assisting the operator
in carrying out the above described method of pressure release, whether
with resilient gasket or non-resilient O-ring seal. That mechanism
includes means of any suitable type for positively preventing the operator
from releasing the clamp or clamps adjacent the closure handle until all
other clamps have been released, thereby effectively forcing the operator
to follow that prescribed order. Convenient apparatus for that purpose
includes abutment structure which acts in response to operation of the
clamp-relieving mechanism to positively lift the cover from its seat. If
the cover is still held fast by other clamps such abutment means has the
effect of positively preventing release of the handle clamps in advance of
their prescribed order.
Such abutment structure has the additional advantage that, when the handle
clamp or clamps are finally released, the clamp relieving action
positively displaces the cover from its seat at the handle side. Hence,
even if, for any reason, residual pressure is still present in the vessel,
a path for its escape is produced in an entirely positive manner prior to
full release of the cover.
The abutment structure to be incorporated in the handle clamps for the
described purposes may take a wide variety of forms, and the specific
structures described herein are intended only as illustration. In clamp
mechanisms in which the pivot axis of the clamp arm is shifted to seal the
closure, the closure member may in general be forcibly lifted from its
seat either by a suitable abutment on the clamp arm itself or by structure
mounted on the handle by which the clamp arm axis is being shifted.
In those clamp structures in which the closure is finally sealed by
forcibly shifting a hook structure relative to the clamp arm, movement of
that hook structure to relieve the closure may actuate suitable abutment
or linkage mechanism which forces slight opening of the closure.
Alternatively, such venting may be produced, for example, by positive cam
action as the clamp arm starts to swing free of the closure, releasing any
residual pressure while the clamp arm is still blocking complete release
of the closure.
BRIEF DESCRIPTION OF THE DRAWING
A full understanding of the invention, and of its further objects and
advantages, will be had from the following description of certain
illustrative ways of carrying it out. That description, and the
accompanying drawings which form a part of it, are intended only as
illustration, and not as a limitation upon the scope of the invention.
In the drawings:
FIG. 1 is a perspective, partly broken away, representing a closure secured
to a pressure vessel by clamping devices embodying certain aspects of the
invention;
FIG. 2 is an exploded perspective representing one of the clamping devices
40a of FIG. 1;
FIG. 3 is a section on line 3--3 of FIG. 4;
FIG. 4 is a fragmentary section on line 4--4 of FIG. 3 representing a
clamping device 40 of FIG. 1;
FIGS. 5 to 7 are sections corresponding to FIG. 4, showing different phases
of operation;
FIGS. 8 to 10 are fragmentary sections similar to FIGS. 4 to 7, but
representing a modification with opposite handle movement;
FIG. 11 is a perspective representing a clamping device with an
illustrative safety latch;
FIG. 12 is a plan representing a clamping device with another illustrative
safety latch;
FIG. 13 is a section on line 13--13 of FIG. 12;
FIG. 14 is an exploded perspective representing one illustrative form of
symmetrical clamping device;
FIG. 15 is an exploded perspective representing another illustrative form
of symmetrical clamping device;
FIG. 16 is a section on line 16--16 of FIG. 13 modified to illustrate
another aspect of the invention;
FIG. 17 is a section on line 17--17 of FIG. 17A, showing a symmetrical
clamping device with adjustment.
FIG. 17A is a plan corresponding to FIG. 17;
FIG. 18 is an axial section of a downwardly opening closure with an
illustrative clamping device and with an air slide for delivering granular
material;
FIG. 19 is a section similar to FIG. 18 but without the air slide and
showing the closure released;
FIG. 20 is an axial section representing an aperture and closure for a
vessel with external pressure, with clamping devices normally operated
from inside and having emergency release from outside;
FIG. 21 is a fragmentary plan representing a clamping device with an
illustrative safety cam mechanism;
FIGS. 22 to 25 are sections on line 22--22 of FIG. 21, showing different
phases of operation;
FIGS. 26 to 28 are sections generally similar to FIGS. 22 to 25, but
representing a clamping device with another illustrative safety cam
mechanism;
FIG. 29 is a schematic elevation partly broken away representing a closure
in clamped position;
FIGS. 29A and 29B are enlarged details of FIG. 29;
FIG. 30 is an elevation corresponding to FIG. 29, but showing partial
release of the closure with blast control in accordance with the
invention;
FIGS. 30A and 30B are enlarged details of FIG. 30;
FIG. 31 is a fragmentary section representing illustrative spring means for
aiding blast control;
FIG. 32 is an elevation representing hinge structure incorporating further
illustrative spring means;
FIG. 33 is a section on line 33--33 of FIG. 32;
FIGS. 34 and 35 are fragmentary sections representing an illustrative
safety cam structure embodied in a known form of clamping device, showing
two phases of operation;
FIGS. 36 and 37 are sections similar to FIGS. 34 and 35, but representing a
modification;
FIG. 38 is a fragmentary perspective representing a closure centering
device and lock, incorporated in a closure handle structure.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
Eccentric Structure
The eccentric structure of the invention will be described primarily as it
is illustratively embodied in the improved closure clamps 40. Those clamps
are shown in a variety of aspects in FIG. 1, in exploded form in FIG. 2,
and in fragmentary axial section in FIG. 3. Each clamp is mounted on
pressure vessel 20 by bracket structure 42, formed of the two support
plates 43. Those plates are permanently welded to neck 24 in mutually
parallel spaced relation on opposite sides of a plane through aperture
axis 21, as shown clearly in FIG. 2 and at the left of FIG. 1 where one
clamp is omitted for clarity of illustration. Bracket plates 43 have
mutually aligned bores 44, which define the pivot axis 45 and receive the
pivot pin 46, typically retained by cotter pins, or the like, 47. Pin 46
forms the primary support for the clamp structure.
Each clamp mechanism 40 comprises a clamp member 50 and an operating handle
member 60. Clamp member 50 comprises the elongated arm 53, which is
laterally enlarged at its inner end to accommodate the relatively large
cylindrical bearing bore 52 with the axis 51. At its free end, clamp arm
50 carries suitable structure for engaging the closure member in certain
angular positions of the arm, together with means for retaining the arm
within such angular working positions in response to such engagement.
Those functions may be performed by a wide variety of hook-like and
retaining structures. They are shown illustratively as the simple angular
hook 54 and the pronounced lip 56, which is adapted to cooperate with the
boss 58 or equivalent structure on the closure member.
Handle member 60 comprises the shank portion 61, carrying at its inner end
the cylindrical hub formation 62 with cylindrical axis 63 perpendicular to
the length of the handle. That hub fits freely in bearing bore 52 of clamp
arm 50 and acts as a plain pivot bearing for the swinging movement of that
arm. The handle member itself is journaled on pivot pin 46 of support 42
by means of a through bore 66 parallel to the cylindrical axis of hub 62
and eccentrically offset from that axis. The magnitude of the eccentric
offset of handle bearing bore 66 may have any desired value not greater
than the hub radius minus that of bore 66. The latter is then
substantially contained within the body of the hub. The handle carries at
its free end a flat handle formation 64 to aid manual application of
torque to hub 62.
A particular advantage of the clamp structure just described is the ease
with which it can be mounted on a bracket of the convenient type shown at
42 without the need for first removing one of the bracket plates. Assembly
of the clamp device itself requires only insertion of handle boss 62 into
clamp arm bore 52. The assembled clamp is then mounted on bracket 42 by
simply placing it between the two bracket plates 43 and inserting pivot
pin 46 through bracket bores 44 and clamp bore 66. The pivot pin is then
retained by whatever retaining device may be provided, such as the cotter
pins 47. Disassembly is correspondingly straightforward and quick.
When so assembled and mounted, the working eccentric of the clamp mechanism
is fully enclosed and protected by bracket plates 43. Thrust washers or
the like may be provided if desired at the inner faces of the bracket
plates, but it is generally preferred that those plates, or the
corresponding opposed faces of an equivalent mounting structure, directly
engage and guide the working parts of the clamp. Moreover, bore 66 in the
handle member typically provides bearing support on pin 46 over the full
pin length between the two mounting plates 43. Hence, the pin is subjected
primarily to shear stress with a minimum of bending moment, providing
optimum strength for a pin of given diameter and thus aiding compact
design of the clamp structure.
The space available between bracket plates 43, indicated at 63 in FIG. 3,
may be divided in any desired ratio between the thickness of the handle
shank 61 and that of clamp member 50. The handle shank typically has a
flat and relatively thin rectangular section, while clamp member 50 is
relatively sturdy and occupies a major portion of dimension 63. The
structure then provides ample bearing surfaces, both for the bearing of
handle 60 on pivot 46 and for clamp arm 50 on the handle, so that adequate
freedom of movement and durability are typically obtainable with plain
bearings, even when operated dry. However, antifriction bearings of any
suitable type may be provided if desired.
Clamp Operation
With the two members of clamp structure 40 assembled and mounted as
described, swinging movement of handle member 60 about its support on
pivot pin 46 causes hub 62 to move in a circular path about support axis
45 at a radius equal to the offset of bore 66 relative to the hub. The
lower end of clamp member 50 is carried along that circular path, and that
movement is translated by the clamp arm into generally vertical
reciprocation of the hook-carrying free end of the clamp arm.
In the present embodiment fully clamped condition is obtained with handle
member 60 generally horizontal and hence perpendicular to the clamp arm,
as shown best in FIG. 4. That position is preferably defined by a positive
stop, which may be provided by contact of the handle boss 67 with the
outer cylindrical surface of aperture neck 24, for example. In that fully
clamped position, hook 54 is drawn forcibly down on closure member boss
58, positively compressing gasket 34 onto aperture rim 25. Lip 56 of the
hook then overhangs the radially inner edge of cover boss 58, retaining
the hook securely on the boss.
Satisfactory control of the degree of compression of sealing gasket 34 in
clamped position of the mechanism can often be obtained by suitable
dimensioning of the parts. However, the clamping action is preferably made
adjustable, as by the bolt 68 which is threaded in the bow of the hook so
its lower end engages the flat upper face of cover boss 58 and forms the
primary working surface of the clamp. Once adjusted, bolt 68 is typically
locked by the nut 69, and normally requires further adjustment only to
compensate wear of the parts or aging or replacement of the gasket.
The phase angle of the eccentric is preferably such that in fully clamped
position pivot axis 45 is somewhat over center with respect to the
direction of the generally upward thrust exerted by the clamp hook upon
hub 62. That thrust line is indicated at 70 in FIG. 4, and the over-center
angle is shown at 72, somewhat exaggerated in size for clarity of
illustration. That overcenter angle may be made adjustable, if desired, as
by providing rotary adjustment between the handle shank and hub 62, or by
making stop boss 67 adjustable, as typically shown in FIG. 17, for
example. Hub 62 may be preferred to form an integral part of the handle,
so that timing of the eccentric action is determined inherently by the
azimuth position of bearing bore 66 about the hub axis. The described
over-center relation in fully clamped position has the advantage of
producing a torque on the handle in a direction tending to maintain it in
clamping position. The mechanism is thus retained securely in clamped
position under most conditions, though a positive latch may be desirable
for additional safety, as described below.
To release the clamp, handle 60 is swung counterclockwise as seen in FIG. 4
about support axis 45 against the described retaining torque, carrying
eccentric hub 62 past dead center and far enough beyond to remove all
clamping force from the closure. If residual pressure should remain in the
pressure vessel while the last clamp is being released, that pressure
typically lifts the closure along with the clamp arm, releasing the seal
and venting the pressure as represented schematically at 73 in FIG. 5.
During that action, lip 56 remains latched over lug 58, safely preventing
full release of the clamp arm until after the closure has fallen back onto
its seat, as in FIG. 6. Lip 56 is then high enough to clear boss 58, as
indicated by the arc 74. Hence the clamp arm may be swung manually,
together with handle 60, in a clockwise direction about support axis 45 to
the idle position of FIG. 7, completely releasing the closure.
The described clamp structure can readily be modified to reverse the
control movement of handle member 60, that is, to produce full clamping of
the closure with the handle member generally parallel to the clamp arm and
to release the cover when the handle is transverse of the clamp arm. Such
modification is illustratively shown in FIGS. 8, 9 and 10 in respective
fully clamped, relieved and fully released positions. The primary
structural difference required to produce that functional change is a
shift in the azimuth position of bearing bore 66 in hub formation 62 of
handle member 60. The required magnitude of that angular shift depends
upon the angular difference between the desired handle clamping positions
and also upon their respective over-center angles. Those over-center
angles are indicated at 72 and 72a in FIGS. 4 and 8, and will be seen to
lie on opposite sides of the respective clamp thrust lines 70 and 70a, in
such directions that the required angular shift of bore 46 equals
approximately the angular difference between the two handle clamping
positions minus the sum of the over-center angles, if any, for the two
embodiments.
The transverse, or handle-down, clamping position of FIGS. 4 to 7, for
example, usually permits the pivot pin to be located somewhat closer to
aperture neck 24, tending to reduce the lateral component of the clamp
thrust for given overhang of the cover rim beyond neck 24. That
configuration also stows the handle close to the vessel wall during normal
use of the apparatus, where it is out of the way and can readily be
latched. Moreover, any friction between hub 62 and the clamp arm tends to
hold the clamp arm in closure limiting position during clamp relieving
handle movement.
On the other hand, under some conditions the operator can more conveniently
exert a strong releasing torque on the handle when its clamping position
is vertical, as in FIG. 8. Also, the vertical or parallel clamping
position is well adapted for remote operation. For that purpose, a
selected degree of friction is provided between eccentric hub 62 and the
clamp arm, and outward swinging of the clamp arm is limited, as by a fixed
or adjustable stop, to a small fraction of the angular throw of the handle
member. Handle member movement, whether in releasing or clamping
direction, then carries the clamp arm along with it between its working
and idle angular positions. Thus only the handle member needs to be
directly driven to operate the clamp.
FIGS. 8, 9 and 10 also show an alternative structure whereby the clamp arm
is retained in working angular position by means of a vertical retaining
flange 57 formed at the extreme periphery of closure 30a and directly
engaging an abutment on the clamp arm. That abutment may conveniently
comprise the side of adjustable bearing member 68.
The shape of the vessel may permit the clamp handle to travel more or less
than the typical range of about 110.degree., and that travel may reach
180.degree. or more, as in FIG. 19, for example. Such differences of
travel can often be compensated by altering the throw of eccentric hub 62.
However, the eccentricity is limited for given hub radius and support
shaft radius, since the shaft must not extend radially outside the
cylindrical hub surface. The maximum eccentricity thus equals the
difference of those radii. If space permits, the eccentricity can be
increased almost without limit for a given shaft diameter by increasing
the diameter of the hub. Such increased eccentric throw may be employed,
for example, to produce a given longitudinal travel of the clamp arm with
a smaller handle swing, or to increase the travel of the clamp arm,
affording even more ample dimensions of retaining lip 56 or its
equivalent.
In structures employing the described tangential relation of support shaft
and eccentric hub, it is sometimes desirable to replace the described bore
66 in hub 62 by an axial channel in the hub surface having a width and
depth both equal to the shaft diameter. Such channel mounting of the
support shaft is illustrated at 100 in FIG. 13, other features of which
are described below. The bottom of that channel is preferably cylindrical,
providing support for the shaft over virtually its whole area in clamped
position of the mechanism.
Safety Latch
To prevent accidental release of the clamping mechanism of the present
invention, it may be desirable, even in presence of the described
over-center feature, to provide a safety latch which positively retains
control handle 60 in clamping position until released by the operator. A
particularly effective and convenient safety latch structure for retaining
a handle in vertical clamping position is shown at 74 in FIG. 11. The pawl
75 is mounted on the shank of handle member 60 for longitudinal sliding
movement, and is strongly biased by the spring 77 toward support axis 45.
The arcuate edge 78 of main bracket 43 is notched at 79 to receive the
pawl working edge in position to retain the handle positively in fully
clamping position. The latch is conveniently releasable by lifting the
hand grip 76, which is coupled to the pawl and is positioned within easy
reach of the fingers of a hand gripping operating handle 64.
A control handle having its clamping position transverse of the clamp arm
may be latched by similar latch mechanism with its pawl inclined in the
opposite direction. Also, additional notches may be provided at selected
angles about support axis 45 for latching the handle in selected
intermediate positions.
A further aspect of the invention provides a preferred form of safety latch
which is especially effective with clamp structures in which full clamping
position of the handle member is generally transverse of the clamp at a
position defined by a positive stop such as stop boss 67 of FIG. 4, for
example. That improved safety latch structure acts between the handle
member and the clamp arm, latching those two members against swinging
movement toward each other. A particular advantage of such a latch is that
it not only retains the handle in clamping position but also retains the
clamp arm in its working position. The latch thus supplements and may even
replace more direct clamp arm retaining mechanisms such as clamp lip 56,
for example.
An illustrative form of latch acting between the handle and clamp members
is shown in FIGS. 12 and 13, comprising the latch pin 82. That pin is
mounted in a transverse bore in handle arm 60 for sliding movement between
the working position illustrated, with its working end projecting from the
handle face that is adjacent the clamp arm, and a retracted position flush
with that handle face. That pin movement is typically driven by the lever
84, pivoted at 84a on the handle with one end engaging the spool 81 on the
other end of the pin. Lever 84 is urged toward working position of the pin
by suitable spring means, shown as the coil spring 86 which is wound about
the lever pivot with one end bearing on handle 60 and the other on the
lever. The lever end 85 opposite to spool 81 serves as handle for shifting
the pin to releasing or idle position, indicated at 83 in FIG. 13. Clamp
arm 50 is formed with a lateral extension 87 terminating at an abutment 88
in position to fittingly engage the side of pin 82 in fully clamped
position of the mechanism. The clamp arm and extension 87 are formed with
a flat surface along the arcuate path followed by the working end of pin
82 during normal operation of handle member 60 for releasing the clamp, as
already described.
In operation of the latch mechanism of FIGS. 12 and 13, latch pin 82 is
automatically projected into the working position shown whenever clamp
member 50 and handle member 60 are in fully clamping position. The pin
prevents movement of either member toward the other, and its movement away
from the other is prevented by positive stops such as the rim of closure
30 and stop boss 67 or its equivalent. To release the clamp, lever handle
85 is momentarily pressed toward handle 60 and then released as that
handle is moved upward. Throughout any other clamp operation, latch pin is
held in idle position by sliding of its end along the sm | | |
