Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
There are applications in which it is desirable to
operate a drum to raise or lower a load at the end of a
cable wound on the drum and in a coordinated manner to
operate a piston to drive a reversible mechanism such that
the mechanism moves in one direction as the drum rotates to
lower the load at the end of the cable and in the opposite
direction as the drum is rotated in the opposite direction
to raise the load.
For example, it may be desirable to move component
parts of a system related to the winch drum between stowed
and deployed positions in response to the winch cable being
unreeled from or reeled upon the winch drum. Further by
way of example, it may be desired to deploy a safety
apparatus simultaneously with unreeling of the winch cable,
and to stow the safety apparatus when the winch cable is
reeled upon the winch drum. Such a safety apparatus may be
deployed and stowed hydraulically by operation of a piston
to drive the reversible safety mechanism.
An electrically driven winch drum is known from United
States patent 2,443,763, wherein an electric motor and
speed reduction gear train are received within a hollow
winch drum and rotationally journaled relative thereto by
bearings. The speed reduction gear train rotationally
drives the winch drum by engagement with an internal gear-
tooth surface thereof. However, the teaching of the '763
patent cannot satisfy the need outlined above.
Particularly, the '763 patent contains not the slightest
suggestion that a coordinated hydraulic output is
desirable, nor how such an hydraulic output might be
achieved.
In an earlier construction the electric motor was
external to the drum and operated an external pump driving
a hydraulic motor. Only the hydraulic motor was carried in
the drum. The resulting hydraulic lines were of
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significant length and there was a complication in matching
the pump output to the hydraulic motor. The result was
that the installation was more complicated, the hydraulic
line losses were substantial, space was not well utilized
and the system was generally somewhat inefficient.
SUMMARY OF THE INVENTION
This invention relates to a piston and drum drive
to system and more particularly to a compact structure wherein
a drum drive and a piston actuating drive are positioned
within the hollow interior of the drum and operate to turn
the drum and to actuate the piston in a desired direction.
Applicant has devised a piston and drum drive
structure in which most of the inefficiencies described
above have been eliminated, both as to use of space and as
to energy consumption. By placing the electric motor
inside the drum and using its shaft output to drive the
drum directly through a gear set, the hydraulic line losses
in driving the drum are eliminated and the hydraulic motor
is totally eliminated. The opposite end of the motor shaft
is connected directly or through a clutch to a compact
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manifold structure also within the drum. The drum further
contains the hydraulic pump, two hydraulic accumulators,
certain necessary relief valves and check valves and ,
interconnecting lines which are very short, leaving as the
only external lines those from the manifold to the external
drive piston.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a longitudinal drawing partly in section
of a piston and drum drive structure according to the
invention;
Figure 2 is a schematic diagram of the hydraulic
circuit employed in the system;
Figure 3 is a side view of the manifold shown in Fig.
1i
Figure 4 is a sectional view along line 4-4 of Fig. 3;
Figure 5 is a view from the rear of the manifold of
ffigure 3.
Figure 6 is a partial sectional view through the w
hydraulic manifold structure employed in the system;
Figure 7 is a sectional view of the manifold of
Figures 3 through,6 taken along line 7-7 of Figure 6; and
-Figure 8 is a sectional view of the manifold of
'25 Figures 3 through 6 taken along line 8-8 of Figure 6.
Figure 9 is a schematic drawing of an alternate form
of motors. assembly incorporated into the structure of Figure
1~ .. .
DESCRIPTION OF.'r'HE PREFERRED EMBODIMENT
Referring,now~to Figure i, a,piston and drum drive
structure is shown~including a drum 10 rotatably supported
in mounting brackets,l2, 14.,Drum 10 carries two sets of ,
sp ral left and rightJhand groves 16, 18 which support .
~oables (not shown) for reeling a load out (down) from the
drum and pulling it in (or up): Carried within the drum is
a D.C.:motor 20 having an output shaft 22. Attached to
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shaft 22 is a pinion gear 24 which drives a gear reduction
gear set including gears 26, 27, and 28. Gear 28 is
carried on a shaft 30 which includes a lead screw and a
follower 32 operable between a pair a limit switches 34, 36
whose function is to cause rotation of the drum 10 to stop
and to reset the polarity of the electric motor drive so
that when next energized, the motor 20 will turn in the
opposite direction. At the opposite end of shaft 30 is a
pinion 38 which drives an internal gear 40 on the inside
surface of the drum 10. By using the shaft 30, the drum is
driven from a point not far displaced from the center
rather than~near one end as would be the case if the
internal gear 40 were driven from the right end of the
drum. At the same time the shaft carrying the driving
pinion 28 also provides a means for operating the limit
switches.
At the opposite end of motor 20, shaft 22 is connected
to an hydraulic power generating system 21 and in
particular to an hydraulic pump thereof which is part of a
manifold structure 42. Shown in phantom is an accumulator
44 including a piston 46 and a spring 48. The manifold 42
including the motor-driven pump, supplies hydraulic fluid
under pressure to an external actuating cylinder 47
including a piston 49 through a pair of conduits 50, 52.
This manifold is described in greater detail in connection
with Figures 3 through 8. Also part of manifold 42 is an
axially extending boss 51 including a bearing 53 supporting
one end of drum 10.
The hydraulic circuit of the above described system is
shown in schematic form on Figure 2 and includes a pump 54
driven by shaft 22 which is reversible along with motor 20
to supply hydraulic fluid under substantial pressure to
either of conduits 56 or 58. These conduits connect
directly with hydraulic accumulators 44 and 45,
respectively. A pair of oppositely directed relief valves
60 and 62 set to pressure levels somewhat above the normal
operating pressure are connected to lines 56 and 58 through
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conduits 64 and 66 respectively such that they are
connected across the pump outlet in each direction. Conduit
56 is connected through a conduit 64 to a check valve 67
and an oppositely directed relief valve 68. These valves
are connected through conduit 50 to one side of a piston 49
in a cylinder 47. Conduit 58 is connected through a
conduit 74 to a check valve 76 and an oppositely directed
relief valve 78, which valves are connected through conduit
52 to the opposite side of piston 49. It will be
appreciated that When motor 20 rotates in a first direction
it will also cause pump 54 to supply fluid under pressure
to accumulator 44 and through check valve 67 and conduit 50
to the left side of piston 49, causing piston 49 to move
toward the right. This will force fluid from the right
side of cylinder 47 through conduit 52 and relief valve 78
to the conduit 58 and the opposite side of the pump 54.
The fluid will also build pressure in accumulator 45 whose
primary purpose is to assure adequate fluid pressure on the
inlet side of the pump to avoid cavitation. Rotation of
the motor 20 in the opposite direction will result in the
pump 54 pumping fluid toward accumulator 45 through check
valve 76 and to the right side of piston 49 in a manner
analogoLS to that described above. When motor 20 is
stopped, fluid is trapped on both sides of piston 47 by
~5 closed relief valves 68 and 78, effectively locking piston
49 in position.
The manifold 42 is,shown and described in detail in
Figures 3 through 8. Figure 3 is a side view of the
manifold 42 including the hydraulic gear pump 54 and a
support structure 80. Figure 4 is a sectional view taken
along line 4-4 of Figure,3. It will be seen that pump 54 ,
is a conventional gear pump including a driving gear 84
carried on the motor~shaft 22 and a driven gear 86 carried
on a stub shaft 88 supported in the housing of manifold 42
and support structure~80. The side of support structure 80
facing the electric motor 20 is shown in Figure 5. In this
view is shown a recess 90 receiving a boss which supports ,
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motor shaft 22. Structure 80 is bolted to the housing of
manifold 42 by means of a plurality of screws 92.
Figure 6 is a view of manifold 42, partly in section,
which shows the opposite side from that shown in Figure 3.
In this view are shown high pressure lines 64, 65 which
receive hydraulic fluid under pressure from pump 54. At its
center, line 64 communicates with a chamber 98 which
receives the output from pump 54 (Fig. 8). Also shown in
Figure 8 is a second high pressure line 66 which
communicates with a second output chamber 100. Chamber 100
is connected with accumulator 44 through a short passage
56. A similar short passage 58 connects chamber 98 with
accumulator 45 which includes a piston 104 and a spring 106
(Fig. 6). Also shown in Figure 8 are bushings 108 and 110
which align and support shafts 22 and 88 carrying pump
gears 84 and 86. The high pressure relief valves 62 and 60
are also shown connected between the high pressure lines 64
and 66. Boss 5I is shown in Figure 6 and in phantom in
Figure 8.
Figure 7, which is a sectional view taken along line
7-7 of Figure 6 cuts through both of accumulators 44 and 45
as well as a number of controlled pressure lines carrying
relief valves 68 and 78. On the downstream side of relief
valves 68 and 78 are outlet passages 50 and 52 which lead
to the actuating cylinder 47. The ends of the passages
shown are plugged since it is necessary to form the various
passages by drilling into the manifold 42 and then
inserting plugs where needed~to close the ends.
Greater flexibility in operation can be provided
through use of a motor of the type shown in Figure 9. Motor
assembly 120 includes, in addition to the motor, a clutch
124 and a.brake, assembly._126,,both of which are mounted on
and coaxial, with the motor.,:shaft 122..;-,,While the clutch and
brake~can be electronically and mechanically connected in a
number of operating configurations, an arrangement which
has been used by the applicant operates with the brake
normally engaged with, the drum, (deenergized) which locks
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the drum to its mounting structure preventing the drum from
rotating and holding the suspended load in position. When
the brake 126 is energized, it is released and the motor
120 then drives the drum as desired to raise or lower the
load. In this arrangement the pump 54 is always connected ,
to the motor 120 so that the piston is actuated whether or
not the load is raised or lowered. This could be reversed
as will be understood by those skilled in the art. The
brake assembly 126 may be manually operated or:it may be
connected into a drum drive control system which includes
means to secure shaft 122 in a desired position and/or to
sense the approach of the load to either its fully extended
position or its fully retracted position such that the
cables are prevented from receiving a severe shock either
from having the load stopped suddenly at the end of the
cable track, or from striking an obstacle at the fully
retracted position.
In operation with the system of Figures 1 through 8,
an electrical request to lower or pay out a load from the
drum results in causing the motor 20 to turn in such
direction as to reel the load out and simultaneously to
drive the pump 54 to move piston 49 to the right in
cylinder 47 (as shown in Fig. 2). Fluid from the right
side of piston 47 will then return to the pump 54 as
described above. A request to raise the load will cause
the electric motor 20 to rotate in the opposite direction,
turning drum 10 in the direction to reel the load in (or
up). At this time, the pump 54 will be turned in the
opposite direction causing piston 49 to move to the left.
~ In the event that motor assembly 120 of Figure 9 is
used, initialoperation of the motor may occur with the ,
clutch"124 disengaged such that the pump turns but the drum
does not turn. In some applications it may be desired to ,
delay operation of tie drum 10 until the pump 54 is at or
near the-end of its cycle or to defer operating the drum IO
at all for some cycles. On the return part of the cycle,
it may be that the operator will want the drum 10 to
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operate at the outset or later in the cycle. Whether it is
desired that the pump 54 operates simultaneously with the
drum 10, or at different times in the cycle, rotation of
the drum 1o in a given direction always results in the pump
54 moving in a particular direction because they are
effectively being driven from the same shaft. The. brake
126 serves primarily to hold the shaft 122 in a desired
position and to prevent it from rotating as might be the
case if some extraneous force were to tension the cables.
1o From the foregoing it will be recognized that the
above described drive system has numerous advantages in
that it is very economical of space, is efficient in the
use of energy, has much simplified hydraulic lines as
compared with the earlier system described above, and as a
result is more reliable.
