Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – Condition responsive means for modifying working member...
Reexamination Certificate
2002-05-30
2003-12-16
Look, Edward K. (Department: 3745)
Motors: expansible chamber type
Plural relatively movable or rigidly interconnected working...
Condition responsive means for modifying working member...
Reexamination Certificate
active
06662706
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an system for use with a distributing assembly, and more particularly to a hydraulic system including functional devices for operating a bulk material distributing assembly.
BACKGROUND OF THE INVENTION
Conventional discharge assemblies are known to use variable speed drives to control the various functional devices on the bulk material discharge assembly. Known functional devices typically include an airlock discharge assembly, a feed roll, a discharge gate, a floor conveyor and/or an agitator.
The functional devices are known to be powered by hydraulics. In particular, conventional hydraulic assemblies comprise a fixed displacement pump wherein the amount of oil being pumped is directly proportional to the rotational speed of the input shaft. In conventional discharge assemblies, an engine typically drives the fixed displacement hydraulic pump to power the functional devices as well as a rotary lobe type blower to generate the airflow used to discharge the bulk material. In many cases, it is desirable to run at lower engine speeds to decrease the airflow rate. However, running the engine at a lower speed also undesirably decreases the hydraulic fluid flow. In order to maintain the desired performance of the functional devices at low engine speeds, the hydraulic pumps must be oversized, resulting in an undesirable excess capacity when running the engine at full speed.
In the past, priority dividers have been used to divide the hydraulic flow from the fixed displacement pumps into a priority flow and an excess flow. Any flow of hydraulic fluid from the fixed displacement pump is first supplied to the priority side to power the priority devices, and only after the total demand for the priority flow is met will hydraulic fluid be supplied to the excess side for powering the non-priority devices. Thus, as the engine speed is reduced, the blower speed reduces, therefore decreasing the airflow. In addition, decreasing the engine speed also reduces the speed of the fixed displacement hydraulic pump, initially decreasing the speed of the non-priority devices while maintaining the speed of the priority devices at a constant rate. By arranging the feeding devices (e.g., the floor conveyor, the agitator, and the feed roll) as non-priority devices, the engine speed may be used to control the bulk material flow rate. Thus, by reducing the engine speed, the material is discharged with the blower at a slower rate, while the feeding devices also introduce the bulk material into the discharge assembly at a slower rate.
FIG. 1
illustrates a conventional hydraulic assembly
100
having five functional devices comprising an airlock discharge assembly
110
, a feed roll
114
, a discharge gate
128
, a floor conveyor
136
, and an agitator
138
. The five functional devices are each run by one of two fixed displacement pumps
102
,
104
. The first fixed displacement pump
102
hydraulically powers the airlock discharge assembly
110
and the feed roll
114
. A pressure compensated adjustable priority divider
108
is provided to divide the hydraulic fluid flow into a priority flow and an excess flow. The airlock discharge assembly
110
is a priority device (i.e., the airlock discharge assembly
110
is powered by the priority flow from the first fixed displacement pump
102
) while the feed roll
114
is a non-priority device (i.e., the feed roll
114
is powered by the excess flow from the first fixed displacement pump
102
). Accordingly, any reduction in the speed of the first fixed displacement pump
102
will first reduce the speed of the feed roll
114
while the speed of the airlock discharge assembly
110
remains constant. This relationship may be beneficial since the feed roll
114
is one means for controlling the feed rate of the bulk material.
An electric control valve
106
and relief
118
is provided to control the rotational direction of the airlock discharge assembly
110
and feed roll
114
. A manual control valve with speed control
112
and relief
116
is also provided to control the speed of the feed roll while allowing the rotational direction of the feed roll to be changed without changing the direction of the airlock discharge assembly
110
. Relief valves
116
and
118
are provided to protect against excessive hydraulic pressure. If the system experiences a maximum pressure, the relief valves
116
and
118
will allow additional hydraulic fluid to drain through the exit line for eventual recovery by the hydraulic tank
142
. The exit line includes a cooler
120
for lowering the temperature of the hydraulic fluid and a filter
122
for removing impurities from the system before recovery by the hydraulic tank
142
.
The second fixed displacement pump
104
hydraulically powers the discharge gate
128
, the floor conveyor
136
, and the agitator
138
. A fixed priority divider
124
divides the hydraulic fluid flow into a priority flow and a non-priority flow such that the discharge gate
128
is a priority device while the floor conveyor
136
and the agitator
138
are non-priority devices. However, since the priority flow of the fixed priority divider
124
is very low when compared to the volume output of the pump
104
at any engine speed, excess flow is always available. The gate circuit on the priority side is protected from over pressurization by the relief valve
130
. A manual control valve
126
with relief
130
is provided to control the discharge gate
128
, opening or closing the gate
128
depending on the direction the handle is actuated.
A dump valve with relief
140
on the excess side of the priority divider
124
provides a means of actuating the floor conveyor
136
and agitator
138
electrically, and provides pressure protection for this portion of the circuit. An additional adjustable priority divider
132
is provided to give the floor conveyor
136
priority over the agitator
138
. Accordingly, any reduction in the speed of the second fixed displacement pump
104
will initially cause the speed of the agitator
138
to decrease prior to any decrease in speed of the conveyor
136
. An electrically adjustable priority flow divider
134
allows the floor conveyor
136
speed to be further controlled, with the excess hydraulic fluid being sent to the hydraulic tank
142
.
Another conventional hydraulic assembly
200
is illustrated in FIG.
2
. The hydraulic assembly
200
has many similar elements as the hydraulic assembly
100
illustrated in
FIG. 1
, as indicated by the identical reference characters. The hydraulic assembly
200
of
FIG. 2
was modified to include three fixed displacement pumps
202
,
204
, and
205
in an attempt to reduce system vibration.
The first fixed displacement pump
202
was provided to power the airlock discharge assembly
110
. A pressure compensated adjustable priority divider
208
is provided to send excess flow through the exit path for later recovery by the hydraulic tank
142
. A relief valve
218
was further provided to protect the pump and hydraulic system.
The second fixed displacement pump
204
was provided to power the feed roll
114
. A relief valve
216
and another electrically actuated dump valve
217
were provided to protect the second fixed displacement pump
204
and the hydraulic system, and provide means for electric actuation of the feed roll
114
.
While functioning advantageously in many applications, these systems are somewhat disadvantageous in that the floor conveyor
136
speed does not slow with a change in engine speed due to being on a priority flow circuit. The relatively low fluid flow requirements of the conveyor
136
will not allow this to be a non-priority function as desired because slowing engine speed would reduce oil flow quickly below an operational level. Moreover, the conventional systems using a fixed displacement pump typically generate excess heat when a great deal of speed control is required. Excess heat is created at pressure drops occurring across the priority dividers. Since the conventional fixed displ
Dinsmore & Shohl LLP
Finn Corporation
Leslie Michael
LandOfFree
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