Abstrict A cone crusher having a lower frame assembly and upper bowl assembly
is provided with hold-down cylinders arranged in pairs which are
oppositely inclined to counteract a rotational impact forces imparted
to the upper bowl assembly. Additionally, the hold-down cylinders
are inwardly inclined toward the gyratory axis of the crusher to
exert a self-centering force on the upper bowl assembly. The paired
and inclined cylinders form a conical truss arrangement that reduces
the need for costly maintenance, repairs, and replacement of the
hold-down cylinders.
Claims What I claim is:
1. A cone crusher comprising
a lower frame assembly having a crusher head eccentrically driven
about a gyratory axis,
an upper bowl assembly, including an inverted concave crusher bowl,
seated to said lower frame assembly such that the crusher bowl of
said upper bowl assembly opposes the crusher head of said lower
frame assembly to form an annular crushing chamber therebetween,
and
a plurality of hold-down cylinders connected between said upper
bowl assembly and said lower main frame assembly for releasably
holding said upper bowl assembly in seating engagement against said
lower frame assembly, each of said cylinders having a base end pivotally
connected to said lower frame assembly and an top end pivotally
connected to said upper bowl assembly,
said hold-down cylinders being inclined from their base ends inwardly
toward said gyratory axis when the upper bowl assembly is in seating
engagement with the lower frame assembly.
2. The cone crusher of claim 1 wherein said eccentrically driven
crusher head has a defined point of nutation, and wherein said hold-down
cylinders are arranged to form the side of a cone, the apex of which
is located substantially above the point of nutation of said crusher
head.
3. The cone crusher of claim 1 wherein said hold-down cylinders
are arranged in pairs and wherein the cylinders in each said pair
of cylinders are further oppositely inclined toward each other from
their base ends.
4. The cone crusher of claim 1 including double pivot means associated
with the base and top ends of each of said hold-down cylinders for
providing each of said base and top ends with two degrees of rotation
when the upper bowl assembly moves relative to the lower frame assembly.
5. A cone crusher comprising
a lower frame assembly having an eccentrically driven crusher head,
an upper bowl assembly including an inverted concave crusher bowl,
said upper bowl assembly being seated on said lower frame assembly
such that the crusher bowl of said bowl assembly opposes the crusher
head of said lower frame assembly to form an annular crushing chamber
therebetween, and
a plurality of hold-down cylinders connected between said upper
bowl assembly and said lower main frame assembly for holding said
upper bowl assembly in seating engagement against said lower frame
assembly, each of said cylinders having a base end pivotally connected
to said lower frame assembly and a top end pivotally connected to
said upper bowl assembly,
said hold-down cylinders being arranged in pairs, with the cylinders
in each pair of cylinders being oppositely inclined toward each
other from their base ends.
6. The cone crusher of claim 5 wherein said crusher head is eccentrically
driven about a gyratory axis and said hold-down cylinders are further
inclined from their base ends inwardly toward said gyratory axis,
wherein said eccentrically driven crusher head has a defined point
of nutation, and wherein said hold-down cylinders are arranged to
form the side of a cone, the apex of which is located substantially
above the point of nutation of said crusher head.
7. A cone crusher comprising
a lower frame assembly having an eccentrically driven crusher head,
an upper bowl assembly, including an inverted concave crusher bowl,
seated to said lower frame assembly such that the crusher bowl of
said bowl assembly opposes the crusher head of said lower frame
assembly to form an annular crushing chamber therebetween,
a plurality of hydraulic hold-down cylinders connected between
said upper bowl assembly and said lower main frame assembly for
holding said upper bowl assembly in seating engagement against said
lower frame assembly, each of said cylinders having a base end pivotally
connected to said lower frame assembly and a top end pivotally connected
to said upper bowl assembly,
said plurality hold-down cylinders being arranged in pairs with
the cylinders in each pair of cylinders being oppositely inclined
toward each other from their base ends, and
hydraulic circuit means for pressurizing said hold-down cylinders
such that the extension of one cylinder in a pair a cylinders is
resisted by the retraction of the other cylinder of such pair of
cylinders so as to counteract torsional forces imparted to said
upper bowl assembly.
8. A cone crusher comprising
a lower frame assembly having an eccentrically driven crusher head,
an upper bowl assembly, including an inverted concave crusher bowl,
seated to said lower frame assembly such that the crusher bowl of
said bowl assembly opposes the crusher head of said lower frame
assembly to form an annular crushing chamber therebetween,
said lower frame assembly and upper bowl assembly having defined
perimeters forming the perimeter of the cone crusher,
a plurality of hydraulic hold-down cylinders connected around the
perimeter of the cone crusher between said upper bowl assembly and
said lower frame assembly for holding said upper bowl assembly in
seating engagement against said lower frame assembly, each of said
cylinders having a base end pivotally connected to said lower frame
assembly and a top end pivotally connected to said upper bowl assembly,
said plurality hold-down cylinders being arranged in pairs with
the cylinders in each pair of cylinders being oppositely inclined
toward each other from their base ends, and
a hydraulic circuit for pressurizing said hold-down cylinders including
at least one accumulator operatively connected thereto.
9. The cone crusher of claim 8 wherein one accumulator is provided
for each two hydraulic cylinders.
10. The cone crusher of claim 9 wherein each of said accumulators
is operatively connected to cylinders that are in different pairs
of cylinders.
11. The cone crusher of claim 10 wherein the cylinders to which
each accumulator is connected are in adjacent pairs of cylinders.
12. The cone crusher of claim 9 wherein each of said accumulators
is operatively connected to cylinders in the same pair of cylinders.
13. The cone crusher of claim 8 wherein an accumulator is provided
for each cylinder.
14. The cone crusher of claim 8 wherein one accumulator is provided
for all cylinder pairs.
15. The cone crusher of claim 8 wherein four pair of eight hydraulic
cylinders are provided at approximately 90 degree intervals around
the perimeter of the crusher, and one accumulator is provided for
each four of said eight cylinders.
16. The cone crusher of claim 15 wherein one accumulator is provided
for two cylinder pairs.
17. The cone crusher of claim 15 wherein one accumulator is provided
for all cylinders of said pairs of cylinders which are inclined
in the same direction.
Description BACKGROUND OF THE INVENTION
The present invention generally relates to cone crushers, also
known as gyratory crushers, which are a widely used type of crushing
machine for reducing rock and other aggregate materials into finer
particles; the invention more particularly relates to the overload
protection feature of a cone crusher which allows uncrushable materials,
such as tramp iron, to pass through the crusher without damaging
the machine's crushing members.
The crushing forces of a cone crusher are generated by the gyratory
motion of a cone-shaped crusher head eccentrically driven in opposition
to an inverted concave or crusher bowl. The crusher bowl is carried
in an upper bowl assembly which seats on the lower frame assembly
housing the crusher head. This bowl assembly is vertically movable
in respect to the lower frame assembly to permit the crusher bowl
to lift away from the crusher head in an overload condition occurring
when an uncrushable enters the annular crushing region between the
crusher head and the bowl. (The ability of the bowl to lift away
from the crusher head also permits the crushing chamber to be cleared
when the machine is not in operation.) Such overload protection
permits uncrushables to pass through the crusher without damaging
the crusher and without causing down time associated with the crusher
repairs.
Known approaches to providing overload protection in a cone crusher
include the use of either coil springs or hydraulic cylinders to
releasably hold the crusher's upper bowl assembly down onto its
lower frame assembly. Of these two approaches, there are a number
of advantages that recommend the use of hydraulic cylinders over
springs. These advantages include tension adjustability, responsiveness
to an overload condition, extendibility and safety--safety because
the hold-down forces exerted by the hydraulic cylinders can be released
when an operator physically accesses the crusher's chamber for maintenance
and cleaning. However, hydraulic cylinders have a particular disadvantage
in that the cylinders normally require considerable maintenance
and frequent repairs due to the extreme forces exerted on the cylinders
under normal operating conditions. More specifically, in conventional
hydraulic overload protection designs, the hydraulic cylinders experience
tremendous radial forces (sometimes referred to herein as lateral
forces) and torsional forces which quickly wear out or damage the
seals and other parts of the cylinders. The radially directed forces
tend to uncenter the upper bowl assembly and occur as the upper
assembly tips up in an overload condition. The torsional or rotating
forces, on the other hand, are impact forces produced whenever the
gyrating crusher head strikes an uncrushable and drives it against
the bowl of the upper bowl assembly.
The use of hydraulic cylinders for overload protection is disclosed
in U.S. Pat. No. 4478373 to Gieschen and U.S. Pat. No. 4615491
to Batch, et al. In both the Batch and Gieschen patents, hold-down
cylinders are designed to release when uncrushables enter the annular
crushing region between the lower and upper assemblies of the crusher.
In each case, the hold-down cylinders extend between the two assemblies
in a vertical orientation with the cylinder's piston rod being connected
to the upper bowl assembly in the case of Gieschen and the lower
frame assembly in the case of Batch. In each case, wear producing
forces, both radial and torsional, will be exerted on the upper
end of the cylinder--that is, on the end connected to the upper
bowl assembly--when the upper bowl assembly reacts to an overload
condition. The present invention is intended to reduce wear on the
hold-down cylinders, and to reduce the maintenance and repair, and
resulting down time, associated therewith.
SUMMARY OF THE INVENTION
Briefly, the invention involves inclining the hydraulic cylinders
of a hydraulic overload protection system of a cone crusher so as
to minimize the effects of radial and torsional forces imparted
to the cylinders during an overload condition. The invention particularly
involves inclining the cylinders inwardly from their base end, that
is, the end secured to the lower frame assembly, in the direction
of the crusher's gyratory axis, such that, the cylinders form a
conical truss arrangement having an apex substantially above the
point of nutation for the eccentrically driven crusher head. This
inclination provides an inwardly directed self-centering force to
the upper bowl assembly which counteracts radially directed stress
on the cylinders.
In another aspect of the invention, the hold-down cylinders are
arranged in pairs with the cylinders in each pair being oppositely
inclined toward each other from their base ends so that they can
provide a circumferential, anti-rotational force component, as well
as a vertical hold-down force component. By suitably pressurizing
cylinder pairs, torsional impact forces imparted to the upper bowl
assembly will be counteracted to relieve stress on the cylinders
resulting from these forces.
It is contemplated that, in the best and preferred mode of the
invention, the cylinders will be arranged in oppositely inclined
pairs and that the oppositely inclined pairs will be inwardly inclined
toward the gyratory axis whereby the cylinders can provide both
anti-rotational and self-centering forces. However, it is understood
that a cone crusher in accordance with the invention could be designed
with either of these features, that is, with either a self-centering
inclined arrangement and/or in an anti-rotational paired arrangement.
The invention still further involves the use of a hydraulic circuit
for pressurizing the hold-down cylinders which includes upwards
of one accumulator for each cylinder and as few as one accumulator
for all cylinders.
It is therefore a primary object of the invention to reduce the
frequency of repairs to the hydraulic cylinders of a conventional
hydraulic overload protection system for a cone crusher. It is a
further object of the invention to reduce the down time associated
with cylinder maintenance, replacement and repair. Other objects
of the invention will be apparent from the following specification
and claims.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view, in cross-section, of a simplified
rendition of a cone crusher using inclined hold-down cylinders in
accordance with the invention.
FIG. 2 is a top plan pictorial view of the simplified cone crusher
shown in FIG. 1.
FIG. 2A is a side elevational view of a cone crusher using inclined
pairs of hold-down cylinders in accordance with the invention.
FIG. 3 is a fragmentary view, in cross-section, of a cone crusher
showing the passage of an uncrushable object through the crushing
chamber of the crusher.
FIG. 4A and 4B are diagrammatic views of a pair of hold-down cylinders
in accordance with the invention showing the inclination of the
cylinder pair.
FIG. 5 is a diagrammatic representation of the cylinder pair of
FIGS. 4A and 4B showing the manner in which the cylinder pairs generate
anti-rotation forces for counteracting the torsional stresses imparted
to the upper bowl assembly when an uncrushable enters the crusher's
crushing chamber as show in FIG. 3.
FIG. 6 is a diagrammatic representation of the self-centering and
anti-rotational forces of cylinder pairs spaced at 90.degree. intervals
about the perimeter of the crusher.
FIG. 7A and 7B is a diagrammatic representation of the deployment
of a single hold-down cylinder in accordance with the invention
for producing self-centering forces, but not anti-rotation forces.
FIG. 8 is a schematic drawing of a hydraulic circuit for pressurizing
the oppositely inclined hold-down cylinder pairs of the invention
shown in FIGS. 1-6.
FIG. 9 is a schematic drawing of an alternative to the hydraulic
circuit shown in FIG. 8.
FIG. 10 is a schematic drawing showing yet another alternative
to the hydraulic circuit shown in FIG. 8.
FIG. 11 is a schematic drawing of a further alternative to the
hydraulic circuit shown in FIG. 8.
FIG. 12 is a schematic drawing of still a further alternative to
the hydraulic circuit shown in FIG. 8.
FIG. 13 is a schematic drawing of yet a further alternative to
the hydraulic circuit shown in FIG. 8.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
Referring now to the drawings, FIGS. 1 and 2 illustrate, in a simplified
form, the basic components of a cone crusher having hydraulic cylinders
for overload protection deployed in accordance with the invention.
Generally, crusher 11 has lower frame assembly 13 which carries
a crusher head 15 and an upper bowl assembly 17 which supports
an inverted crusher bowl or concave (not separately shown in FIG.
1 but shown in FIG. 3) over and in opposition to the crusher head
so as to form a crusher crushing chamber 19. It can be seen that
the crushing head is driven in a gyratory motion about gyratory
axis 21 by an eccentric 23 which is coupled to drive shaft 25 by
means of skirt gear 27 and pinion 29. The material to be crushed
in crushing chamber 19 is fed through hopper 45 situated on top
of the upper bowl assembly. A gyrating distributor 47 connected
to the top of the crusher head 15 by means of extension 49 acts
to distribute material fed into the hopper evenly around the crusher
head so that one side of the crushing chamber does not become overloaded.
The upper bowl assembly 17 seats to the lower frame assembly so
that it can separated from the lower assembly as hereinafter described.
The upper bowl assembly is also constructed such that the height
of the crusher bowl can be raised or lowered to adjust the clearance
in crushing chamber 19. More specifically, the upper bowl assembly
has an inner frame 43 having a threaded outer cylinder wall 41 held
in a threaded seating ring 33. The seating ring, which seats against
the top flange 39 of the lower frame assembly when the upper and
lower assemblies of the crusher are engaged, includes an outwardly
flared annular portion 35 which engages the inwardly flared annular
portion 37 of the top flange in order to center the upper bowl assembly
in respect to the axis of the crusher. Height adjustment of the
crusher bowl is accomplished by rotating the inner frame 43 of the
upper bowl assembly within the seating ring.
The upper bowl assembly is held in seating engagement to the lower
frame assembly by means of hydraulic hold-down cylinders 51 which
are arranged in pairs distributed at 90.degree. intervals about
the perimeter of the crusher. Each cylinder of the cylinder pairs
has a non-extensible base end 53 connected to the lower frame assembly,
an extensible top end in the form of piston rod 55 connected to
the upper bowl assembly, and is inclined in two planes. First, the
cylinder pairs are oppositely inclined from their base ends 53 toward
each other such that the axis of the cylinders intersect at the
seating ring 33. Secondly, the cylinder pairs are inclined inwardly
from their base toward gyratory axis 21 such that the cylinder pairs
form a conical truss arrangement with the sides of the conical truss,
as represented by phantom lines A, intersecting at an apex located
well above the point of nutation P of the eccentrically driven crusher
head. As further described below, this conical truss arrangement
provides an advantageous self-centering force for relieving the
stress on the cylinders when the upper bowl assembly tilts in reaction
to the over-load pressure of an uncrushable passing through crushing
chamber 19.
Referring to FIG. 2A, the hold-down cylinders 51 are connected
between the lower frame assembly and upper bowl assembly such that
both the non-extensible and extensible ends of the cylinders are
free to pivot about two perpendicular axes to permit the cylinders
to follow radial or rotational movements of the upper bowl assembly
when the upper bowl assembly breaks contact with the lower frame
assembly. Specifically, the nonextensible base end of each cylinder
has shackle 57 pivotally connected to coupling arm 59 of collar
61. Collar 61 is in turn pivotally connected between the projecting
flanges 63 located at the bottom of the lower frame assembly 13.
Similarly, the extensible top end of each cylinder has a shackle
65 pivotally connected to a coupling plate 67 which extends downwardly
from of a collar 69 which in turn is pivotally connected between
gussets 71 extending between the top wall 73 and side wall 75 of
the seating ring. It can be seen that this coupling arrangement
provides two axes of rotation for the base and top ends of the cylinders:
the base end of the cylinders will be permitted to pivot around
a first pivot axis formed by the pivot connection between shackles
57 and arm 59 of collar 61 and a second pivot axis formed by the
pivot connection of the collar 61 to flanges 63. Likewise, the top
of the cylinders will be permitted to pivot about a first pivot
axis formed by the pivot connection of shackles 65 to coupling plate
67 and about a second pivot axis formed by the pivot connection
between the collar 69 and gussets 71.
The hold-down cylinder pairs are arranged around the perimeter
of the housing along with other operative parts of the crusher,
including accumulators 77 which are part of the hydraulic control
circuit hereinafter described, thread binder cylinders 79 which
lockingly engage the threads of seating ring 41 to the threads 41
on the inner frame of the upper bowl assembly during operation of
the crusher, the chain drive unit 81 for driving chain 83 to rotate
adjustment cap 85 for rotating inner frame 43 within seating ring
33 and clearing cylinders 87 for raising the upper assembly from
the top flange of the lower frame assembly in order to clear the
crushing chamber. It is noted that the clearing cylinders could
be eliminated altogether, thereby eliminating the added plumbing
associated with the clearing cylinders, by providing hold-down cylinder
pairs 51 which are double acting cylinders, that is, which, in addition
to being pressurized from the top to generate a hold down force,
can also be pressurized from the bottom to extend the cylinders
to raise the upper bowl assembly.
FIG. 3 shows the upper bowl assembly 17 and the crushing chamber
19 in greater detail and particularly illustrates the separation
of the upper bowl assembly from the lower frame assembly when an
uncrushable passes through the crushing chamber. As an uncrushable,
such as dozer tooth 89 enters the lower region of crushing chamber,
it strikes the mantle 91 of the crusher head and the crusher bowl
or concave 93. (In FIG. 3 it is seen that the crusher bowl is a
separate crushing member mechanically secured to inner frame 43
of the upper bowl assembly.) The resulting overload condition is
relieved by the hold-down cylinders 51 which permit the upper bowl
assembly to be pushed away from the top flange 39 of the lower frame
assembly and from the tapered guide pins 95. The entire upper bowl
assembly is thus caused to tilt upwardly at the side of the crusher
where the uncrushable enters the crushing chamber, as indicated
by arrows B. In a conventional crusher, the degree of tilt can be
expected to be in the range of 21/2.degree.. As above-mentioned,
such tilting of the upper bowl assembly will tend to uncenter the
upper bowl assembly in relation to the crusher's axis 21 resulting
in significant lateral forces being exerted on the hold-down cylinders
if the hold-down cylinders are conventionally arrayed in a vertical
orientation in respect to the upper bowl assembly.
The operation of the hold-down cylinders is now further described
in reference to FIGS. 4-6 which illustrate the inclination of the
cylinder pairs and the forces exerted by these cylinders on the
upper bowl assembly. Referring to FIGS. 4A, 4B and 5 the hold-down
cylinders 51A, 51B of cylinder pair 97 are generally comprised of
cylinder portions 99 100 pistons 101 102 and piston rods 103
104. The cylinders exert a hold-down force as denoted by force vectors
F1 by providing hydraulic pressure behind the pistons 101 102 as
indicated by shaded areas 105 106. The hold-down force thusly exerted
by the cylinders is an axial force in reaction to an upwardly directed
axial force vector F2 at the top of the cylinder.
FIG. 4A shows the inward inclination of cylinder pair 97 which
produces a self-centering force for counteracting the upper bowl
assembly's tendency to be uncentered by an uncrushable. Optimally,
the angle at which the cylinder pairs are inclined as shown in FIG.
4A is chosen such that the axial force vectors of the cylinders
are perpendicular to the plane of the upper bowl assembly when the
upper bowl assembly is in its maximum allowable tilt angle as represented
by arrows B in FIG. 3. The degree of perpendicularity between the
plane of the upper bowl assembly and the cylinders will generally
determine the degree of lateral shear forces of the cylinders. Suitably,
the inward inclination of the cylinder pairs will be a range of
about 10 to 20 degrees, placing the apex of the resulting conical
truss arrangement well above the point of nutation P of the crusher
head.
FIG. 5 shows the manner in which the oppositely inclined cylinder
pairs can produce anti-rotational forces to counteract the torsional
impact forces imparted to the upper bowl assembly when the crusher
head strikes the uncrushable dozer tooth 89 shown in FIG. 3. As
the upper bowl assembly 17 breaks contact with the top flange of
the lower assembly, the frictional forces normally counteracting
any torsional forces in the upper bowl assembly drop to approximately
zero causing a sharp increase in the torsional or rotational forces
exerted on the cylinders. These torsional forces are represented
by rotational force vectors F3 in FIG. 5. Provided the cylinder
pairs are connected to a suitable hydraulic control circuit as discussed
in more detail below, rotational movement of the cylinder pair will
produce a counteracting rotational force due to resulting pressure
changes in the cylinders. Specifically, as the cylinder pair moves
counter-clockwise as shown in FIG. 5 piston 101 of cylinder 51A
moves upwardly compressing the hydraulic fluid volume 105 behind
the cylinder, while piston 102 of cylinder 51B moves downwardly
to expand the hydraulic fluid volume 106. Differential pressures
for producing an anti-rotational force will result so long as the
cylinders of the cylinder pair are hydraulically isolated as described
below.
FIG. 6 shows the resultant force vectors of the hydraulic cylinder
pair described in connection with FIGS. 4 and 5 for four pairs of
cylinders spaced at 90.degree. intervals about the perimeter of
the crusher. Specifically, in response to a tilting movement of
the upper bowl assembly 17 each cylinder pair will produce self-centering
force vectors F2 to counteract the tendency of the upper bowl assembly
to become uncentered as it tilts away from the lower frame assembly
13 and anti-rotational force vectors F3 to counteract torsional
impact forces that occur when the upper bowl assembly breaks contact
with the top flange of the lower frame assembly.
It shall be appreciated that while the best mode of the invention
calls for a pairing of hydraulic cylinders, the invention contemplates
the possible use of non-paired cylinders which provide a self-centering
force only, as illustrated in FIGS. 7A and 7B. Specifically, in
a non-paired cylinder configuration, a plurality of hold-down cylinders
that are inwardly inclined as illustrated in FIG. 7A could be connected
between the lower frame assembly and the seating ring 33A of the
upper bowl assembly at equally spaced intervals about the perimeter
of the crusher. As shown in FIGS. 7A and 7B, each cylinder 52 would
provide a self-centering force as denoted by force vector F2 on
the seating ring. Such an arrangement, however, would produce a
minimal anti-rotational force component.
FIGS. 8-13 show alternative hydraulic circuits for pressurizing
the hold-down cylinder pairs illustrated in FIGS. 1-6. FIG. 8 illustrates
a hydraulic circuit having one accumulator for every two hydraulic
cylinders wherein the accumulators are hydraulically connected to
oppositely inclined cylinders. The circuit illustrated in FIG. 8
would not produce anti-rotational forces because increased pressure
in one cylinder is taken up in the other of the cylinders connected
to the same accumulator. This is also true in respect to the circuits
shown in FIGS. 12 and 13. In FIGS. 9 10 and 11 oppositely inclined
cylinders are isolated from one another so that anti-rotational
forces can be produced as described above.
More specifically, in FIG. 8 cylinder pairs 97 which are pictorially
shown as being connected to seating ring 33 hydraulically communicate
with four accumulators 77A through hydraulic lines 78A with one
accumulator being provided for two oppositely inclined cylinders
of adjacent cylinder pairs. Each accumulator circuit is connected
through an adjustable flow control valve 80 to hydraulic pressure
and return lines (not shown) through a directional solenoid valve
(not shown); each accumulator circuit can additionally be isolated
manually by means of valves 82A.
In FIG. 9 each cylinder of cylinder pairs 97 communicates with
its own accumulator 77B thereby totally isolating each cylinder
from the other cylinders. This circuit doubles the number of required
accumulators and accumulator circuits.
In FIG. 10 one accumulator 77C is provided for two cylinders,
but in this case, each accumulator circuit connects to cylinders
having the same direction of inclination such that cylinders, e.g.
cylinders 51L, of one inclination are isolated from oppositely inclined
cylinders 51R. As compared to the circuit of FIG. 9 this circuit
reduces the number of accumulators and shut-off valves needed while
providing the cylinder pairs the capability of producing anti-rotational
force components.
The hydraulic circuits shown in FIGS. 11 and 12 have just two accumulators
77D and 77E for the hydraulic cylinder pairs 97: in FIG. 11 all
similarly inclined cylinders communicate with a single accumulator
whereas in FIG. 12 one accumulator handles alternating cylinder
pairs. In FIG. 13 all the cylinders pairs 97 are connected to but
a single accumulator 77F. The reduction in the number of accumulators
in the circuits of FIGS. 11-13 will reduce plumbing requirements
and costs; such a reduction, it is believed, can be achieved without
substantial loss in operating efficiency, provided the accumulators
have sufficient capacity.
It is noted that various electrical interlocks (not shown) can
be provided to prevent possible damage to the crusher when its various
systems are in use. For example, The hold-down cylinders can be
interlocked to the clearing cylinders such that the two can not
operate simultaneously. An interlock can also be provided to signal
a drop in pressure in the hold-down cylinders. Such interlock systems
are well known in the art.
Therefore, it can be seen that the present invention provides hydraulic
overload protection for a cone crusher in which wear and tear on
the hydraulic hold-down cylinders of the system is reduced. While
the invention has been described in considerable detail in the foregoing
specification and accompanying drawings, it shall be understood
that it is not intended that the invention be limited to such detail.
For example, the invention is not limited to the use of hydraulic
hold-down cylinders, but is intended to encompass other types of
cylinders, for example, magnetic cylinders. However, hydraulic cylinders
are considered to be the most suitable choice of extensible hold-down
devices. Also, it is understood that the extensible portion of the
cylinders may be connected to the lower frame assembly instead of
the upper bowl assembly such that the extensible end of the cylinders
becomes the cylinder's defined base end and the non-extensible end
of the cylinders becomes the top end connected to the seating ring.
This configuration is not recommended, however, since it will place
considerable stress on the hose connections to the cylinders. |