Abstrict A hydraulic accumulator particularly useful in connection with
gyratory crushers of the type in which the crusher head and shaft
are hydraulically supported so that when the crusher head encounters
uncrushable material such as "tramp iron" the crusher
head can move down to pass the tramp iron, causing at least some
of the hydraulic fluid supporting the crusher shaft to be ejected
to a hydraulic accumulator. A plurality of gyrations of the crusher
may occur before the tramp iron passes. The accumulator chamber
which receives the hydraulic fluid ejected from beneath the crusher
shaft contains a gas precharged elastic bladder. Hydraulic fluid
is admitted to the accumulator chamber through a poppet valve built
into the accumulator structure, which valve is normally spring biased
to a closed position against its valve seat. When the hydraulic
pressure in the conduit connecting the hydraulic cylinder beneath
the crusher shaft to the accumulator decreases to a predetermined
value during a portion of each cycle of gyration of the crusher,
the biasing spring closes the poppet valve and traps the hydraulic
fluid in the accumulator chamber before any significant reverse
hydraulic flow can occur, thereby preventing "water hammer"
in the conduit connecting the hydraulic cylinder of the gyratory
crusher to the accumulator. The poppet valve or the valve seat therefor
are provided with a bleed passage or passages which permit a very
restricted return hydraulic flow from the accumulator to the hydraulic
cylinder of the gyratory crusher when the poppet valve is in closed
position.
Claims The embodiments of the invention in which an exclusive property
or privilege is claimed are defined as follows:
1. In combination, a gyratory crusher, said crusher comprising
a crusher head and a shaft-like member in supporting relation to
said crusher head, means forming part of the crusher structure and
defining a crusher hydraulic chamber for receiving a hydraulic fluid
which is in supporting relation to said shaft-like member and to
said crusher head, a hydraulic accumulator located in spaced relation
to said crusher, a hydraulic conduit fluidly connecting said crusher
hydraulic chamber and said hydraulic accumulator, said hydraulic
accumulator comprising a hollow accumulator chamber for receiving
hydraulic fluid from said crusher hydraulic chamber whereby to permit
lowering of said shaft-like member and said crusher head when said
crusher encounters uncrushable material, said crusher head during
the period when it is attempting to pass uncrushable matter through
the crusher moving toward the uncrushable material on one part of
each gyratory cycle whereby to increase the hydraulic pressure in
said hydraulic conduit and moving away from said uncrushable material
on another part of each gyratory cycle whereby to reduce the hydraulic
pressure in said hydraulic conduit, an elastic bladder member positioned
in said accumulator chamber, said bladder member containing a precharge
of a gas at a predetermined precharge pressure, valve means incorporated
as part of the accumulator structure for controlling flow of hydraulic
fluid between said hydraulic conduit and said accumulator chamber,
spring means engaging said valve means and biasing said valve means
toward a closed position, said valve means being openable to admit
hydraulic fluid from said hydraulic conduit into the interior of
said accumulator chamber during said one part of the gyratory cycle
in which said crusher head is moving toward said uncrushable material,
said spring means being adapted to close said valve means to prevent
any significant reverse hydraulic flow from said accumulator chamber
into said hydraulic conduit during said another part of the gyratory
cycle when said crusher head is moving away from said uncrushable
material, whereby to prevent "water hammer" in said hydraulic
conduit, and bleed passage means fluidly communicating the interior
of said accumulator chamber with said hydraulic conduit, said bleed
passage means being effective to permit a restricted reverse flow
of hydraulic fluid from said accumulator chamber into said hydraulic
conduit and thus to said crusher hydraulic chamber with said valve
means in closed position whereby to cause a gradual upward movement
of said shaft-like member and said crusher head after the uncrushable
material has passed through said crusher.
2. The combination defined in claim 1 in which said bleed passage
means is provided in said valve means.
3. The combination defined in claim 1 in which said accumulator
structure includes a valve seat means for said valve means, said
valve means being engageable with said valve seat means when said
valve means is in closed position, and said bleed passage means
is provided in said valve seat means.
4. In a hydraulic accumulator for use in combination with a gyratory
crusher and in which said crusher comprises a crusher head and a
shaft-like member in supporting relation to said crusher head, and
in which said crusher additionally comprises means forming part
of the crusher structure and defining a crusher hydraulic chamber
for receiving a hydraulic fluid which is in supporting relation
to said shaft-like member and to said crusher head, said hydraulic
accumulator being adapted to be located in spaced relation to said
crusher and being adapted to be fluidly connected by a hydraulic
conduit to said crusher hydraulic chamber, and in which said hydraulic
accumulator comprises a hollow accumulator chamber for receiving
hydraulic fluid from said crusher hydraulic chamber whereby to permit
lowering of said shaft-like member and said crusher head when said
crusher encounters uncrushable material, said crusher head during
the period when it is attempting to pass uncrushable material through
the crusher moving toward the uncrushable material on one part of
each gyratory cycle whereby to increase the hydraulic pressure in
said hydraulic conduit and moving away from said uncrushable material
on another part of each gyratory cycle whereby to reduce the hydraulic
pressure in said hydraulic conduit, and in which an elastic bladder
member is positioned in said accumulator chamber, said bladder member
containing a precharge of a gas at a predetermined precharge pressure,
the improvement which comprises valve means incorporated as part
of the accumulator structure for controlling flow of hydraulic fluid
between said hydraulic conduit and said accumulator chamber, spring
means engaging said valve means and biasing said valve means toward
closed position, said valve means being openable to admit hydraulic
fluid from said hydraulic conduit into the interior of said accumulator
chamber during said one part of the gyratory cycle in which said
crusher head is moving toward said uncrushable material, said spring
means being adapted to close said valve means to prevent any significant
reverse hydraulic flow from said accumulator chamber into said hydraulic
conduit during said another part of the gyratory cycle when said
crusher head is moving away from the uncrushable material, whereby
to prevent "water hammer" in said hydraulic conduit, and
bleed passage means fluidly communicating the interior of said accumulator
chamber with said hydraulic conduit, said bleed passage means being
effective to permit a restricted reverse flow of hydraulic fluid
from said accumulator chamber into said hydraulic conduit and thus
to said crusher hydraulic chamber with said valve means in closed
position whereby to cause a gradual upward movement of said shaft-like
member and said crusher head after the uncrushable material has
passed through said crusher.
5. The hydraulic accumulator defined in claim 4 in which said bleed
passage means is provided in said valve means.
6. The hydraulic accumulator defined in claim 4 in which said accumulator
structure includes a valve seat means for said valve means, said
valve means being engageable with said valve seat means when said
valve means is in closed position, and said bleed passage means
is provided in said valve seat means.
7. A hydraulic accumulator adapted to be connected to a hydraulic
conduit, said hydraulic accumulator comprising a hollow accumulator
chamber for receiving hydraulic fluid from said hydraulic conduit,
an elastic bladder member positioned in said accumulator chamber,
said bladder memeber containing a precharge of a gas at a predetermined
precharge pressure, valve means incorporated as part of the accumulator
structure for controlling flow of hydraulic fluid between said hydraulic
conduit and said accumulator chamber, spring means engaging said
valve means and biasing said valve means toward a closed position,
said valve means being openable to admit hydraulic fluid from said
hydraulic conduit into the interior of said accumulator chamber
when the force exerted on said valve means in a valve opening direction
by the hydraulic fluid in said conduit exceeds the sum of the forces
exerted on said valve means in a valve closing direction from within
said accumulator chamber and by said spring means, said spring means
being adapted to close said valve means to prevent any significant
reverse hydraulic flow from said accumulator chamber into said hydraulic
conduit when the force acting on said valve means in a valve opening
direction by the hydraulic fluid in said hydraulic conduit decreases
to a predetermined relation to the force in said accumulator chamber
acting in a valve closing direction on said valve means, and bleed
passage means fluidly communicating the interior of said accumulator
chamber with said hydraulic conduit, said bleed passage means being
effective to permit a restricted reverse flow of hydraulic fluid
from said accumulator chamber into said hydraulic conduit.
8. The hydraulic accumulator defined in claim 7 in which said bleed
passage means is provided in said valve means.
9. The hydraulic accumulator defined in claim 7 in which said accumulator
structure includes a valve seat means for said valve means, said
valve means being engageable with said valve seat means when said
valve means is in closed position, and said bleed passage means
is provided in said valve seat means.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to hydraulic accumulators adapted for use
with gyratory crushers of the type in which hydraulic means is used
to support the mainshaft on which the crushing head is mounted or
otherwise supported, although the hydraulic accumulator of the invention
is not necessarily restricted to such use; and the invention also
relates to the combination of such hydraulic accumulator with a
gyratory crusher.
2. Description of the Prior Art
It is well known in the prior art relating to gyratory crushers
of the type using hydraulic means for supporting the mainshaft on
which the crushing head is attached or otherwise supported to provide
means for lowering the crushing head and the supporting shaft thereof
when uncrushable material such as "tramp iron" enters
the crushing chamber, whereby to permit the crusher to pass the
tramp iron. "Tramp iron" is the term used in the art to
designate an uncrushable object such as a metal dipper tooth or
the like, for example, which is foreign to the mineral ore being
processed by the crusher. The tramp iron relief is provided by conducting
the hydraulic liquid beneath the piston which supports the crusher
mainshaft to a hydraulic accumulator whereby the mainshaft and the
crushing head supported thereby are lowered to permit passage of
the tramp iron or the like through the crushing chamber. The hydraulic
means for supporting the crusher shaft also permits lowering of
the crusher shaft when other abnormal operating conditions are encountered,
whereby to prevent breakage of the crusher parts. Examples of prior
art patents showing the use of hydraulic accumulators for the purpose
just mentioned in connection with gyratory crushers are U.S. Pat.
No. 2579516 issued to Alexander J. Roubal on Dec. 25 1951 and
U.S. Pat. No. 2667309 issued to George D. Becker on Jan. 26 1954.
Upon the presence of uncrushable material such as tramp iron in
the crushing chamber of the gyratory chusher, during one gyration
of the mainshaft to which the crushing head is attached or by which
the crushing head is supported, 50 percent of the time the crushing
head is closing on the tramp iron, forcing hydraulic fluid such
as oil into the accumulator, and the other 50 percent of the time
the crushing head is moving away from the tramp iron, and the accumulator
is attempting to force the oil back to the cylinder in which the
support piston which underlies the mainshaft is positioned.
Since the time period for one gyration of the mainshaft in a gyratory
or cone crusher is a fraction of a second, the hydraulic oil must
change directions rapidly. It is not possible for the oil to make
a complete round trip from the cylinder for the support piston to
the hydraulic accumulator and back to the cylinder in the very short
time period of one gyration. Therefore, in the absence of a check
valve in the hydraulic conduit connecting the crusher hydraulic
cylinder to the accumulator, the oil going from the cylinder to
the accumulator meets the oil going from the accumulator to the
cylinder "head on." When this happens, "water hammer"
occurs. The water hammer will build up in severity through each
successive cycle of gyration until the connecting conduit from the
cylinder to the accumulator breaks.
To prevent water hammer in a situation such as that just described,
it has been the prior art practice to place a check valve in the
hydraulic conduit connecting the accumulator to the cylinder for
the support piston, this check valve being so constructed as to
permit free flow of hydraulic oil from the crusher hydraulic cylinder
to the accumulator but to provide a retarding action on the flow
of the oil from the accumulator back to the cylinder. With each
successive gyration, the crushing head hits the tramp iron and more
oil is forced into the accumulator until the crushing chamber is
opened far enough to pass the tramp iron. Upon clearance of the
tramp iron through the crushing chamber, the oil is forced back
to the cylinder for the support piston by the accumulator, setting
the crushing head in its normal operating position. A check valve
of the type just described connected in the hydraulic conduit from
the accumulator to the cylinder for the support piston and permitting
free flow of oil from the cylinder to the accumulator but retarding
flow of oil from the accumulator back to the cylinder is diagrammatically
shown as item 25 in the aforementioned U.S. Pat. No. 2579516 issued
to Alexander J. Roubal. The use of a separate check valve such as
the check valve 25 shown in the aforementioned U.S. Pat. No. 2579516
and the associated pipe fittings are relatively expensive.
STATEMENT OF THE INVENTION
Accordingly, it is an object of the present invention to provide
a hydraulic accumulator particularly adapted for, although not necessarily
restricted to, use with gyratory crushers of the type in which hyraulic
means is used to support the mainshaft on which the crushing head
is mounted or otherwise supported, the hydraulic accumulator being
characterized by the fact that it incorporates within the accumulator
structure a check valve means which retards the return hydraulic
flow from the accumulator to the cylinder for the support piston
associated with the mainshaft of the gyratory chamber, whereby to
substantially eliminate "water hammer" in the hydraulic
conduit connecting the crusher hydraulic cylinder to the accumulator.
It is a further object of the invention to provide a hydraulic
accumulator for use with gyratory crushers of the type in which
hydraulic means is used to support the mainshaft on which the crushing
head is mounted or otherwise supported, and in which the accumulator
incorporates a built-in check valve means which eliminates the necessity
for a check valve in the conduit connecting the accumulator to the
cylinder for the support piston associated with the mainshaft of
the gyratory crusher for the purpose of restricting the return hydraulic
flow from the accumulator to the cylinder as shown, for example,
by the aforementioned U.S. Pat. No. 2579516 issued to Alexander
J. Roubal; and in which the accumulator incorporating the built-in
check valve in accordance with the present invention results in
a substantial economic saving as compared to the prior art arrangement
which required an accumulator and a check valve separate from each
other.
It is a further object of the invention to provide in combination
with a gyratory crusher of the type in which hydraulic means is
used to support the mainshaft on which the crushing head is mounted
or otherwise supported a hydraulic accumulator which is hydraulically
connected to the cylinder for the support piston associated with
the mainshaft of the crusher, and which hydraulic accumulator includes
a built-in valve means for restricting return hydraulic flow from
the accumulator to the cylinder, whereby to avoid "water hammer"
when the crusher is in the process of clearing uncrushable material
such as tramp iron through the crushing chamber of the crusher.
In achievement of these objectives, there is provided in accordance
with an embodiment of the invention a hydraulic accumulator particularly
useful in connection with, although not necessarily restricted to,
gyratory crushers of the type in which the crusher head and shaft
are hydraulically supported in such manner that when the crusher
head encounters uncrushable material such as tramp iron or encounters
some other abnormal condition requiring a downward movement of the
crusher head and shaft, the crusher head can move down to pass the
tramp iron or the like, causing at least some of the hydraulic fluid
supporting the crusher shaft to be ejected to a hydraulic accumulator.
The accumulator chamber which receives the hydraulic fluid ejected
from beneath the crusher shaft contains an elastic bladder member
of rubber or the like containing a precharge of gas. In an embodiment
of the invention, the hydraulic fluid is admitted to the accumulator
chamber through a poppet valve built into the accumulator structure,
which valve is normally biased to closed position against its valve
seat by a biasing spring, the poppet valve being opened against
the pressure of the gas precharged bladder and against the biasing
spring force to admit hydraulic fluid to the accumulator chamber
when the crusher is working to eject tramp iron from the crushing
chamber. When the hydraulic pressure in the hydraulic conduit connecting
the hydraulic cylinder beneath the crusher shaft to the accumulator
and pushing on the valve in one direction subsequently decreases
to a value which is equal to or slightly greater than the hydraulic
pressure in the accumulator chamber pushing on the valve in the
opposite direction, the biasing spring closes the poppet valve and
traps the hydraulic fluid in the accumulator chamber before any
reverse hydraulic flow can pass through the open valve. The poppet
valve or the valve seat therefor are provided with a bleed passage
or passages which permit a very restricted return hydraulic flow
from the accumulator to the hydraulic cylinder of the gyratory crusher
when the poppet valve associated with the accumulator is in closed
position. By thus restricting the reverse hydraulic flow from the
accumulator to the hydraulic cylinder of the gyratory crusher, "water
hammer" is prevented in the hydraulic conduit connecting the
hydraulic cylinder of the gyratory crusher to the accumulator, particularly
during the interval in which the gyratory crusher is attempting
to pass the tramp iron. The invention is also directed to the combination
with a gyratory crusher of the aforementioned hydraulic accumulator
having the built-in hydraulic flow control valve.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and advantages of the invention will become apparent
from the following description taken in conjunction with the accompanying
drawing in which:
FIG. 1 is a view partially in vertical elevation and partially
in vertical section of a gyratory crusher having the cylinder for
the support piston for the gyratory crusher head and shaft hydraulically
connected to a hydraulic accumulator in accordance with the invention,
the accumulator in FIG. 1 being provided with a bleed hole or passage
through the head of the poppet valve of the accumulator for the
purpose of restricting or retarding return hydraulic flow from the
accumulator to the cylinder for the support piston of the gyratory
crusher;
FIG. 2 is a fragmentary view showing a modified accumulator construction
in accordance with the invention in accordance with which the bleed
hole or passage is located in the valve seat rather than in the
valve head;
FIG. 3 is a fragmentary view of a still further modified hydraulic
accumulator construction in accordance with the invention in which
the head of the poppet valve is provided with a bleed groove or
grooves in the tapered surface of the valve head which interfaces
with the valve seat; and
FIG. 4 is a still further modified embodiment of a hydraulic accumulator
construction in accordance with the invention in which the tapered
surface of the valve seat which interfaces with the head of the
poppet valve when the poppet valve is in closed position is provided
with a bleed groove or grooves for the return flow of hydraulic
fluid from the accumulator to the cylinder for the support piston
of the gyratory crusher.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawing, there is shown a gyratory crusher
generally indicated at 10 of the spider bearing type. Crusher 10
includes an upper frame section 12 within which is supported a bowl
liner or concave 14. A crusher head 16 is mounted on shaft 18 and
a crusher mantle 20 is secured on shaft 18 and on crusher head 16
by a head nut 22. A crushing chamber 24 is defined between bowl
liner 14 and crusher mantle 20. The lower portion of shaft 18 is
journalled within the eccentric vertical bore of an eccentric 26
by means of a bearing sleeve or liner 28 positioned within the eccentric
bore.
Eccentric 26 is cylindrical and is supported for rotation by a
pedestal-like inner frame portion 30 and by horizontal portion 32A
of the base portion generally indicated at 32. A bearing sleeve
or liner 33 is positioned between eccentric 26 and frame portion
30 to journal eccentric 26 for rotation. Eccentric 26 is rotated
by the engagement of ring gear 34 on eccentric 26 with the mating
pinion gear 36 mounted on drive shaft 38.
Rotation of eccentric 26 by means of gears 34 36 imparts a gyratory
movement to crusher head 16 and crusher shaft 18 about a fulcrum
located on a vertical axis central of crushing chamber 24 and of
spider hub 44 as is well known in the art, and as set forth, for
example, in U.S. Pat. No. 3813047 issued to James D. Torrence
et al on May 28 1974.
The spider assembly generally indicated at 41 is suitably supported
on the upper end of upper frame section 12 spider assembly 41 including
a plurality of radially extending arms 42 which supports a centrally
located spider hub, generally indicated at 44. Spider hub 44 is
provided with an axial passage 46 therethrough. Axial passage 46
of spider hub 44 is lined with a flanged spider bushing 48. The
upper end of crusher shaft 18 extends through and is journalled
by bushing 48 of spider hub 44. The upper end of crusher shaft 18
is provided with a replaceable wear sleeve 50.
The lower end of shaft 18 is supported by a piston 52. A step bearing
generally indicated at 54 is interposed beneath the lower end of
shaft 18 and the upper surface of piston 52. The base portion 32
and the sleeve or liner 35 which lines the interior of base portion
32 cooperate with lower horizontal base portion 37 to define a cylinder
or chamber 56 in which piston 52 is vertically movable. Hydraulic
liquid such as oil is admitted to or ejected from cylinder 56 whereby
to control the height of piston 52 in cylinder 56 and thus whereby
to control the vertical height of crusher shaft 18 and of crusher
head 16 mounted on crusher shaft 18.
Shaft 18 and crusher head 16 may be vertically adjusted by either
the introduction of hydraulic fluid into cylinder 56 beneath the
lower end of piston 52 for the purpose of elevating shaft 18 and
crusher head 16; or conversely, by the withdrawal of hydraulic fluid
from cylinder 56 beneath piston 52 for the purpose of lowering shaft
18 and crusher head 16. The interior of cylinder 56 beneath piston
52 is hydraulically connected by means of hydraulic conduits 58
and 59 in series with a shut-off valve 63 to a reversible pump 60
which is connected to a reservoir 61 for hydraulic fluid, such as
oil. Crusher head 16 and shaft 18 are maintained at the desired
vertical setting by introducing the appropriate volume of hydraulic
fluid beneath piston 52 by means of pump 60 after which operation
of pump 60 is discontinued and shut-off valve 63 is closed. Pump
60 may be operated in either direction to change the adjusted vertical
setting of crusher head 16 and shaft 18. "Make-up" hydraulic
liquid to replace losses of hydraulic liquid may also be introduced
as required, in the same manner as just described.
The space beneath piston 52 in cylinder 56 is also connected by
hydraulic conduit 58 to the hydraulic inlet plug 74 of a hydraulic
accumulator generally indicated at 70.
Except for the modifications to be hereinafter described, hydraulic
accumulator 70 may be a commercially available hydraulic accumulator
of the type manufactured by Greer Olaer Products, a Division of
Greer Hydraulics Inc., 5930 W. Jefferson Boulevard, Los Angeles
16 Cal.
The accumulator generally indicated at 70 includes an outer shell
72 defining a hollow chamber having positioned on the interior thereof
a flexible or elastic bladder member 76 made of rubber or other
suitable elastomeric material. The bladder 76 is in fluid communication
at the upper end thereof relative to the view shown in FIG. 1 with
the gas valve assembly generally indicated at 78 through which a
suitable gas such as nitrogen, for example, may be introduced into
the hollow interior of bladder 76 whereby to precharge the interior
of bladder 76 to a predetermined desired gas pressure.
The inlet plug 74 of accumulator 70 extends through an opening
in the lower end of outer shell 72 and is suitably secured in a
fixed and leak-proof position relative to outer shell 72 by a retaining
ring 80 an O-ring 82 a washer 83 and a lock nut 84. The upper
end of inlet plug 74 is provided with a tapered inner periphery
to define a valve seat 86 adapted to receive the valve head 90 of
a poppet valve generally indicated at 88. The poppet valve 88 includes
a valve stem 92 which is slidably received by the guide portion
94 of inlet plug 74. A helical spring 96 surrounds the lower end
of valve stem 92. The upper end of spring 96 bears against the under
surface of guide portion 94 of inlet plug 74 while the lower end
of spring 96 bears against a spring seat defined by a washer 98
which bears against the upper surface of a nut member 100 which
is threadedly engaged with the lower portion of valve stem 92.
Spring 96 normally maintains poppet valve 88 in the closed position
shown in the view of FIG. 1 in which valve head 90 is seated on
valve seat 86. Spring 96 is a "light" spring, that is,
a spring having a low spring rate such as a spring rate in the range
5 to 10 pounds. The "spring rate" is the force required
to compress the spring a distance of one inch.
An important feature of the construction is the provision of a
bleed hole or passage 102 in head 90 of poppet valve 88 for the
purpose of restricting return flow of hydraulic fluid from the interior
of accumulator shell 72 to cylinder 56 associated with gyratory
crusher 10 for the purpose of preventing "water hammer"
as will be described in more detail hereinafter.
In the view shown in FIG. 1 of the drawing, crusher head 16 and
shaft 18 of gyratory crusher 10 are shown in a raised position which
is assumed to be the "set" position of the crusher for
a particular crushing operation. In this position of crusher head
16 and crusher shaft 18 and assuming that no uncrushable material
such as tramp iron has entered crushing chamber 24 and that no
other abnormal operating condition exists which would tend to cause
lowering of the crusher head and crusher shaft, bladder 76 of accumulator
70 will be expanded by the internal pressure of its precharge of
nitrogen gas so as to occupy substantially the entire internal volume
of shell 72 as seen in FIG. 1 and there will be no hydraulic oil
present within accumulator shell 72.
The precharge pressure of the gas in the elastic bladder member
76 should be such that under normal operating conditions of the
gyratory crusher and in the absence of any uncrushable material
such as tramp iron in the crushing chamber, and in the absence of
any abnormal operating condition which would tend to cause lowering
of the crusher head and crusher shaft, the hydraulic pressure in
conduit 58 connecting crusher cylinder 56 to hyraulic accumulator
70 and pushing upwardly on valve 88 will be no greater than the
sum of the downwardly acting pressure of the gas precharged bladder
76 of accumulator 70 plus the downward biasing force of spring 96
which biases poppet valve 88 to closed position. Under "normal"
crushing conditions bladder 76 will be expanded to fill substantially
the entire internal volume of hollow accumulator tank or chamber
72 and there will be no hydraulic oil or hydraulic fluid in accumulator
chamber 72.
There is shown in FIG. 2 a fragmentary view of a modified bleed
passage arrangement for metering the return flow from the accumulator
70 to the hydraulic cylinder 56 associated with the gyratory crusher.
Except for the modified bleed passage arrangement to be described,
the structure shown in FIG. 2 is otherwise similar to the structure
shown and described in connection with the embodiment of FIG. 1
and similar parts in FIG. 2 have the same reference numerals as
FIG. 1 applied thereto, except that the subscript "A"
forms part of the reference numerals in the embodiment of FIG. 2.
Thus, in the modified embodiment of FIG. 2 one or more bleed passages
102A are located in valve seat 86A but in outwardly spaced relation
to the tapered surface of valve seat 86A which interfaces with valve
head 90A. In other words, bleed passage or passages 102A of the
embodiment of FIG. 2 lie in the valve seat and communicate the hollow
interior of plug member 74A and hence the connected hollow interior
of conduit 58 with the hollow interior of accumulator chamber 72A
even when valve member 88A is closed.
Referring now to FIG. 3 there is shown a still further modified
arrangement of the bleed passage or passages which may be used instead
of the arrangement of the bleed passage or passages shown in FIGS.
1 and 2. The structure shown in FIG. 3 is otherwise similar to the
accumulator structures shown in FIGS. 1 and 2 and similar parts
are similarly numbered, except that the reference numerals in the
embodiment of FIG. 3 have the subscript "B" at the end
of the respective reference numerals.
Referring to the modified embodiment of FIG. 3 it will be seen
that bleed passages 102B are provided in valve head 90B at the surface
of the valve head which interfaces with valve seat 86B. Bleed passages
102B fluidly communicate the hollow interior of accumulator tank
72B with the hollow interior of inlet plug 74B which, in turn, communicates
with the hollow interior of hydraulic conduit 58 even when valve
member 88B is seated on valve seat 86B.
Referring now to FIG. 4 there is shown a still further modified
bleed passage or passages which retard the reverse hydraulic flow
from the accumulator chamber back to the hydraulic cylinder associated
with the gyratory crusher. Except for the difference in the location
of the bleed passages to be hereinafter described, the structure
shown in FIG. 4 is the same as that previously described in connection
with FIGS. 1 2 and 3 and similar reference numerals will be used
as in the other figures except that in FIG. 4 the subscript "C"
follows the various reference numerals. Thus, in the modified embodiment
of FIG. 4 the tapered surface of valve seat 86C which interfaces
with the tapered surface of valve head 90C of valve member 88C is
provided with one or more grooves 102C whereby when valve head 90C
is seated on the valve seat, as seen in FIG. 4 the hydraulic fluid
in the accumulator chamber may bleed through groove or grooves 102C
from the accumulator chamber into the hollow interior of valve plug
74C and thus into hydraulic conduit 58 when the hydraulic pressure
in the interior of accumulator chamber 72C is greater than the hydraulic
pressure in the hollow interior of valve plug 74C and in the connected
hollow interior of conduit 58 which leads to hydraulic cylinder
56 associated with gyratory crusher 10.
Description of Operation
When gyratory crusher 10 is operating normally and has not encountered
a piece of tramp metal or other uncrushable material and has not
encountered any other abnormal operating condition which would tend
to cause crusher head 16 and crusher shaft 18 to move in a downward
direction relative to the view of FIG. 1 the hydraulic pressure
in conduit 58 will be such that the elements of accumulator 70 will
be in the position shown in FIG. 1 in which valve 88 is closed,
and in which the precharge gas pressure within elastic bladder 76
will cause bladder 76 to expand to fill substantially the entire
volume of the hollow interior of accumulator tank 72 as seen in
the view of FIG. 1.
Assume now that a piece of tramp metal such as a metal dipper tooth,
or other uncrushable material, is present in the crushing chamber
24. While the time required for the crusher to pass or clear this
uncrushable material may vary widely, typically the time required
for the crusher to clear or pass the uncrushable material, such
as the tramp iron, may vary from, for example, 1 second to about
1/2 minute. Thus, if the eccentric 26 which causes the gyratory
movement of the crusher head and shaft is rotating 360 revolutions
per minute, which is a typical speed of rotation of the eccentric,
the number of cycles of gyration required for the crusher to clear
the uncrushable material may vary from, for example, 6 cycles of
gyration to, for example, 180 cycles of gyration.
Consider what happens on the first cycle or gyration of the gyratory
crusher: During one half of the first cycle of gyration, crushing
head 16 is closing on the tramp metal, causing the hydraulic pressure
in conduit 58 which connects the crusher to accumulator 70 to increase
to a value which exceeds the sum of the downwardly acting pressure
exerted by the gas precharged bladder 76 on valve 88 plus the downward
biasing force of spring 96 which also biases poppet valve 88 toward
closed position. When this condition occurs, poppet valve 88 rises
off of and above valve seat 86 and admits some hydraulic fluid from
hydraulic conduit 58 into the interior of accumulator chamber 72.
This hyrdraulic fluid admitted into accumulator chamber 72 will
cause some compression of bladder 76. Also, the increment of flow
of hydraulic fluid out of crusher hydraulic cylinder 56 which occurs
during the half cycle of gyration when the crusher head is closing
on the tramp metal causes a corresponding lowering of the crusher
shaft and crusher head.
On the next half cycle of the first cycle of gyration after encountering
the tramp metal, crushing head 16 moves away from the tramp metal
and consequently the hydraylic pressure in conduit 58 leading to
accumulator 70 begins to decrease. When the decreasing pressure
in hydraulic conduit 58 pushing upwardly on valve 88 drops to a
pressure value at which it is just equal to or possibly even slightly
higher than the hydraulic pressure in accumulator chamber 72 pushing
downwardly on valve 88 spring 96 closes valve 88 into engagement
with valve seat 86 corresponding to the position seen in FIG. 1
of the drawing, before there can be any reverse flow of hydraulic
fluid through the open valve 88 from accumulator chamber 72 back
into hydraulic conduit 58 leading to the crusher. It is true that
after valve 88 is closed, as just described, there will be a small
amount of hydraulic fluid passing through bleed passage or passages
102 (FIG. 1) from accumulator chamber 72 back into hydraulic conduit
58 on the aforementioned "next" half cycle of gyration
just described when the hydraulic pressure in accumulator tank 72
becomes greater than the decreasing hydraulic pressure in conduit
58. However, the amount of hydraulic fluid which will pass through
bleed passage 102 in the reverse direction toward hydraulic cylinder
56 of crusher 10 when valve 88 is closed on the aforementioned "next"
half cycle of the first cycle of gyration after encountering the
tramp metal, and when the crusher head is moving away from the tramp
metal, as just described, is negligible, as compared to the amount
of hydraulic fluid which entered accumulator chamber 72 on the preceding
half cycle of the first cycle of gyration (when crusher head 16
was closing on the tramp metal), since the ratio of the size of
the opening for passage of hydraulic fluid when poppet valve 88
is open, as compared to the size of the fluid passage through bleed
passage 102 when valve 88 is closed is typically of the order of
magnitude of 140:1.
Thus, one the first cycle of gyration of the crusher head and shaft
after the tramp metal or other uncrushable material is first encountered,
as well as on all of the subsequent cycles of gyration until the
tramp metal is finally cleared and passes through the crusher, only
a negligible flow of hydraulic fluid occurs in the reverse direction
from accumulator chamber 72 back into hydraulic conduit 58 and
thus, the problem of "water hammer" is eliminated since
during the period when the tramp iron or other uncrushable material
is being cleared, substantially all of the hydraulic flow is from
the crusher hydraulic cylinder 56 through hydraulic conduit 58 to
accumulator chamber 72 and there is only a negligible flow of hydraulic
fluid in the reverse direction from accumulator chamber 72 back
into hydraulic conduit 58.
The sequence of events which occurs on the two half cycles of the
first cycle of gyration of head member 16 and shaft 18 of the gyratory
crusher after first encountering the tramp iron or other uncrushable
material, in which the crusher head first moves toward or closes
on the uncrushable material to increase the hydraulic pressure in
hydraulic conduit 58 and to cause hydraulic flow from crusher cylinder
56 through conduit 58 to accumulator chamber 72 with the crusher
head then moving away from the uncrushable material to decrease
the hydraulic pressure in hydraulic conduit 58 is substantially
repeated on each subsequent gyration of the crusher head and shaft
during the time interval in which the crusher is attempting to clear
or pass the uncrushable material.
As more hydraulic fluid is admitted to the accumulator chamber
72 on subsequent cycles of gyration after the first cycle of gyration
just described, the amount of hydraulic fluid in the accumulator
chamber 72 continues to increase, increasing the pressure of the
gas confined within elastic bladder 76 and causing bladder 76 to
become reduced in volume and to raise up out of contact with valve
head 90 away from the position shown in FIG. 1 of the drawing.
As additional hydraulic fluid is admitted into accumulator chamber
72 with each successive gyration of the crusher head during the
period while the crusher is attempting to clear the uncrushable
material, the hydraulic pressure inside the accumulator will continue
to increase, with the result that in order to open valve 88 to admit
additional hydraulic fluid into accumulator chamber 72 on any successive
cycle of gyration, the hydraulic pressure in conduit 58 required
to open valve 88 becomes successively greater with each successive
cycle of gyration.
As more and more hydraulic fluid is admitted from hydraulic cylinder
56 through hydraulic conduit 58 into accumulator chamber 72 piston
52 which supports crusher shaft 18 and crusher head 16 will continue
to lower until finally the crusher shaft and crusher head have been
sufficiently lowered to permit passage through crushing chamber
24 of the tramp iron or other uncrushable material.
When the tramp iron has finally passed out of crushing chamber
24 there is a sudden reduction in the hydraulic pressure in hydraulic
conduit 58 and, at the moment when the level of the decreasing hydraulic
pressure in conduit 58 acting upwardly on valve 88 reaches a value
slightly greater than or equal to the pressure in accumulator chamber
72 acting downwardly on valve 88 biasing spring 96 causes valve
88 to close into engagement with valve seat 86 in the same manner
as previously described. However, when valve 88 closes after the
uncrushable material has finally been cleared through the crushing
chamber, valve 88 then remains closed, and the higher pressure of
the hydraulic fluid in accumulator chamber 72 as compared to the
now reduced hydraulic pressure in hydraulic conduit 58 causes the
compressed bladder 76 to expand and slowly eject the hydraulic fluid
in accumulator chamber 72 through the bleed passage or passages
102 at a retarded rate of flow. This causes piston 52 beneath crusher
head 18 to gradually move upwardly until crusher head 16 is again
positioned at its "set point" corresponding to normal
crusher operation. When this has occured, all of the hydraulic fluid
in accumulator chamber 72 will have been ejected from chamber 72
and elastic bladder 76 will have expanded to substantially completely
occupy the entire volume of accumulator chamber 72 as shown in FIG.
1 of the drawing, with the precharged bladder 76 bearing against
the upper surface of valve head 90 in the same manner as shown in
FIG. 1.
While the operation of accumulator 70 in conjunction with gyratory
crusher 10 has been described in connection with the embodiment
of FIG. 1 an accumulator structure, such as 70A, 70B, and 70C,
incorporating the various modified arrangements of the bleeder passages,
such as 102A, 102B and 102C, would operate in the same manner as
described in connection with the embodiment of FIG. 1.
From the foregoing detailed description of the invention, it has
been shown how the objects of the invention have been obtained in
a preferred manner. However, modifications and equivalents of the
disclosed concepts such as readily occur to those skilled in the
art are intended to be included within the scope of this invention.
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