U.S. patent number 3,596,565 [Application Number 04/844,839] was granted by the patent office on 1971-08-03 for remotely controlled hydraulic system.
Invention is credited to Duane Edward Atkinson.
United States Patent |
3,596,565 |
Atkinson |
August 3, 1971 |
REMOTELY CONTROLLED HYDRAULIC SYSTEM
Abstract
Heavy duty equipment such as construction equipment with
adjustably positioned, remotely controlled, hydraulically actuated
movable members.
Inventors: |
Atkinson; Duane Edward
(Burlingame, CA) |
Family
ID: |
25293767 |
Appl.
No.: |
04/844,839 |
Filed: |
July 25, 1969 |
Current U.S.
Class: |
91/392; 91/512;
105/240; 298/35M; 91/2; 91/459; 105/311.1 |
Current CPC
Class: |
B60P
1/56 (20130101); F15B 11/16 (20130101); F15B
21/08 (20130101); F15B 2211/423 (20130101); F15B
2211/3122 (20130101); F15B 2211/41509 (20130101); F15B
2211/41527 (20130101); F15B 2211/45 (20130101); F15B
2211/327 (20130101); F15B 2211/6326 (20130101); F15B
2211/40515 (20130101); F15B 2211/411 (20130101); F15B
2211/7128 (20130101); F15B 2211/3111 (20130101) |
Current International
Class: |
B60P
1/56 (20060101); B60P 1/00 (20060101); F15B
21/08 (20060101); F15B 11/16 (20060101); F15B
11/00 (20060101); F15B 21/00 (20060101); F15b
011/16 () |
Field of
Search: |
;91/411,361,2
;105/240,311,311C ;298/35M |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Geoghegan; Edgar W.
Claims
I claim:
1. A control system for use in equipment of the type which includes
hydraulic fluid supply means, a movable member, hydraulically
driven motive means connected to drive said movable member and
hydraulic lines connected between said supply means and said motive
means comprising fluid metering means including a hydraulic motor
having an output shaft which rotates responsive to the flow of
fluid through said motor for metering the fluid supplied to said
motive means, interrupting means including a control valve for
controlling the flow of fluid to said motive means and means
responsive to predetermined rotation of said shaft for controlling
said valve means to interrupt the flow of fluid to said motive
means to stop said movable member at a predetermined position.
2. A control system as in claim 1 in which said control valve
comprises a solenoid valve and said means responsive to
predetermined rotation of said shaft comprises electric circuit
means.
3. A control system as in claim 2 in which said electrical means
includes a switch, and said shaft carries a cam adapted to operate
said switch.
4. A control system as in claim 3 wherein said electrical means
comprises a potentiometer adapted to be driven from said shaft and
a bridge circuit associated with said potentiometer.
5. A control system as in claim 1 wherein said means for
interrupting the flow of fluid to said motive means comprises a
hydraulically actuated valve means, and means are associated with
said shaft for controlling the flow of hydraulic fluid to said
valve means.
6. A control system for use in equipment of the type which includes
hydraulic fluid supply means, a movable member adapted to be moved
between first, second and adjustable and intermediate positions, a
hydraulically driven motive means connected to drive said movable
member between said first and second positions and hydraulic lines
connected between said supply means and said motive means adapted
to supply hydraulic fluid to said motive means to move the same
from said first to said second position and back including a fluid
metering means in the hydraulic lines for metering fluid supplied
to said motive means and providing a measure thereof, a control
valve disposed in said fluid hydraulic lines to control the flow of
fluid to said motive means, means responsive to a predetermined
measure of fluid for controlling said valve to interrupt the flow
of fluid to said motive means to stop said movable member at said
intermediate position, and means for thereafter controlling said
valve to selectively apply fluid to said motive means to
selectively move the movable member to the first or second
position.
7. A control system as in claim 6 wherein said fluid metering means
includes a movable member and wherein said means responsive to a
predetermined measure of fluid comprises means responsive to
movement of said movable member.
8. A control system as in claim 7 wherein said fluid metering means
comprises a hydraulic motor with a rotatable shaft and said means
responsive to movement is responsive to rotation of said shaft.
9. A control system as in claim 8 in which said control valve
comprises a solenoid valve and said means responsive to
predetermined rotation of said shaft comprises electric circuit
means.
10. A control system as in claim 9 in which said electrical means
includes a switch, and said shaft carries a cam adapted to operate
said switch.
11. A control system as in claim 10 wherein said electrical means
comprises a potentiometer adapted to be driven from said shaft and
a bridge circuit associated with said potentiometer.
12. A control system as in claim 8 wherein said means for
interrupting the flow of fluid to said motive means comprises a
hydraulically actuated valve means, and means are associated with
said shaft for controlling the flow of hydraulic fluid to said
valve means.
13. A control system as in claim 8 in which said shaft includes
first and second portions with slip means disposed between said
first and second portions whereby the second portion can stop while
the first portion continues to rotate, and stop means for
interrupting rotation of said second portion prior to said movable
member reaching its first and second positions.
14. A control system as in claim 13 including a gear reduction
means associated in said first shaft portion whereby said second
portion rotates one revolution responsive to movement of said
movable member between the first and second positions.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to heavy duty, remotely
controlled, hydraulically operated equipment, and more particularly
to equipment for the heavy construction industry.
In the construction industry, materials such as sand, dirt, rock,
gravel and the like are often transported by earth moving equipment
to be used as fill. One type of such equipment includes a
tractor-trailer combination. The trailer comprises a large
top-loading bin having sloping sides and ends which converge at
discharge openings at the bottom. One or more pairs of doors or
closures are adapted to selectively open and close the discharge
opening.
Successful use of large size trailers in heavy construction service
requires features in the door operating system that may or may not
be required in other services. Unlike mining or other fixed haul
operations, embankment dam construction involves hauling different
kinds of materials from different locations on a balanced basis to
allow the various zones of the dam to be raised in an integrated
fashion. Furthermore, the hauling unit or trailer must provide the
preliminary distribution of the material on the dam rather than
simply dumping a full load at a fixed terminal point.
The optimum size of the dumped windrow is dependent upon the type
and condition of the material being dumped, the width of the zone
being raised, the lift height allowable at that point, and proper
integration with the final spreading and compacting equipment in
use. If the windrow is large, then it becomes difficult to handle
with equipment of normal size. For these reasons, it is important
that trailers have an adjustable door opening for dumping that is
intermediate between full-closed and full-open, thus allowing
control of the size of the dumped windrow. After the dumping is
completed, the doors are preferably opened fully to completely
clear the trailer, particularly when hauling wet or sticky
materials.
Absent any drift, the intermediate door opening position can be
left unchanged for the duration of a given haul operation. At other
times, however, changing dumping zones, changing pits, changes in
material, moisture content, etc., may require frequent adjustment
of the intermediate door opening setting or position.
One type of trailer includes two completely independent door
systems which first allow dumping the rear half of the trailer,
thereby maintaining weight on the tractor driving wheels, and then
dumping the front half of the trailer to complete the operation.
Each pair of doors operates independently of the other and has
three control positions; full-closed, an adjustable intermediate
position, and full-open. The three opening settings for each of the
two door systems are controlled by the operator as he drives across
the fill and the dumping zone.
One type of system for setting the intermediate opening includes a
cam which moves with the door to operate a cam valve when the door
reaches a predetermined intermediate opening position. The
actuation of the cam valves causes interruption of the hydraulic
flow to the associated door operating ram thereby holding the door
at this position. This type of direct control subjects the sensing
elements to the rugged environment prevailing at the doors. Changes
in the door opening setting require access to the door region and
sensing element which may not be easily accessible.
The setting or adjustment of the adjustable position of the
controlled member should not require special tools and should be
simple and convenient whereby adjustment can be expeditiously
accomplished in the field. The control system components should
preferably be rugged for use in the construction environment or
located in a position in which they are protected from the
environment.
Remote control of other hydraulically actuated heavy-duty equipment
is also important for example, the positioning of cutting blades in
scrapers and levelers; positioning of concrete mixing and handling
equipment, loaders and the like used in the construction
industry.
SUMMARY OF THE INVENTION AND OBJECTS
There is provided hydraulically controlled equipment of the type
which includes a hydraulically actuated movable means such as doors
or blades. Control means are located at the operator location for
permitting the operator to control the position of the movable
member, for example, doors between two extreme positions and an
adjustable intermediate position. Said hydraulic system includes a
fluid metering device connected in the fluid line between the
hydraulic supply means and the hydraulic motive means, such as
motor or rams, which activiate the members to meter the fluid
supplied to the motive means, and means responsive to said metering
device for interrupting the flow of hydraulic fluid to said motive
means to stop the member or doors at an adjustable intermediate
position when a predetermined amount of hydraulic fluid has been
supplied. The system also includes means for automatically
compensating for drift.
It is a general object of the present invention to provide an
improved hydraulic system for controlling a hydraulically operated
member.
It is another object of the present invention to provide a door
opening system for earth moving equipment in which the intermediate
door opening position may be simply, quickly and readily adjustable
by unskilled field personnel or by the operator without special
tools and without taking the truck out of a haul system longer than
is absolutely necessary.
It is a further object of the present invention to provide a
hydraulic system for operating movable members which is extremely
reliable and trouble free.
It is still a further object of the present invention to provide a
hydraulic system in which the control sensing means are remotely
located in a protected portion of the material carrier.
It is another object of the present invention to provide a system
in which the controls for the operators are simple to operate.
The foregoing and other objects of the invention will become more
clearly apparent when taken in conjunction with the following
description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of a tractor trailer
incorporating the present invention.
FIG. 2 is an enlarged view of the doors associated with the trailer
of FIG. 1.
FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1 and
showing the doors in the closed position.
FIG. 4 shows the doors in FIG. 3 in their fully open position.
FIG. 5 is a schematic diagram of an electrical control system for
controlling the hydraulic door rams for operating the doors.
FIG. 6 is a schematic diagram of another electrical control system
incorporating the present invention.
FIG. 7 is a schematic diagram of a hydraulic control system for
controlling operation of hydraulically operated members.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention is described with reference to typical earth moving
equipment. It will, however, be apparent that the invention is
equally as useful in connection with the control of other
hydraulically driven members. Referring to Figure 1, the equipment
comprises a tractor 11 adapted to tow a trailer 12 which is filled
with construction material 13. The trailer is suitably attached to
the tractor by means of a gooseneck attachment 14. The trailer
illustrated includes discharge openings 16 each having a pair of
discharge doors 17a, 17b. The discharge doors are mounted on spaced
pins 18 disposed on opposite ends of the opening 16. The pins are
engaged by door brackets 19. Hydraulic rams 21, 22 located on
opposite sides of the trailer engage the corresponding door. The
rams are adapted to pivot the doors around the pivot point pins 18
and open the doors upwardly as shown in Figure 4. It will be
apparent that hydraulic motors or operators may be substituted for
the rams.
In accordance with the preferred embodiment of the present
invention, the hydraulic fluid supplied to the hydraulic rams is
controlled by an electrical control system of the type shown in
Figure 5. Referring to Figure 5, the hydraulic system includes a
hydraulic pump 31 which, in the present example, is located on the
tractor and provides hydraulic fluid under pressure from the
reservoir 12 to the hydraulic rams 21, 22 disposed on opposite
sides of the trailer. The hydraulic fluid from the pump passes
through a pressure relief valve 32 which is adapted to continuously
supply hydraulic fluid to the hydraulic line 33 at predetermined
pressure. However, when the piston 34 associated with each ram
reaches its limiting position and no further fluid can flow, the
bypass valve 32 bypasses the fluid to the line 36 back to the
reservoir 32. The pressure relief valve thereby controls and
maintains constant pressure on the line 33. A return line 37 serves
to return fluid from the hydraulic pistons to the reservoir 12.
A solenoid valve 38 is connected in the fluid supply and return
lines 33 and 37 and serves to selectively connect these lines to
the hydraulic lines 41, 42 which supply fluid to opposite sides of
the pistons 34. The four-way valve includes actuating solenoids 43
and 44. When the solenoid 43 is actuated, it serves to connect the
supply and return lines 33, 37 to the lines 42, 41, respectively,
as shown by arrows, to move the pistons in the direction indicated
by the arrows 47 which is the direction for opening the doors
connected to the pistons. When the valve is not energized, lines
33, 37 and 41, 42 are blocked as indicated at 48 whereby no fluid
flows to or from the hydraulic pistons. The pistons are thereby
maintained in a fixed position. When the solenoid 44 is energized,
the lines 33, 37 are connected to lines 41, 42, respectively, and
the pistons are moved in the direction shown by the arrows 49 which
is the closing direction for the doors connected to pistons 34. As
previously described, when the pistons achieve either of the two
extreme positions, the pistons are maintained under the
predetermined pressure supplied to line 33 thereby keeping the
doors in the fully open or fully closed position with predetermined
force.
Hydraulic motors 51 and 52 are connected in parallel in the line
42. The output shaft of each hydraulic motor will rotate in
proportion to the amount of fluid being supplied to the respective
piston and will, therefore, inferentially indicate the position of
the piston. If the output shafts of the two motors are mechanically
coupled, the motors form a flow divider that synchronizes the
operation of the two rams. The two metering motors 51, 52 can be
replaced by a single duplex pump motor that combines both these
units in a single casing. Units of this type are readily available
and widely used as flow dividers.
If the door or member associated with one ram tends to bind or
otherwise operate slowly, the fluid divider will automatically
increase the pressure on that ram and reduce the pressure on the
other. In the extreme case, the slow ram will see twice the system
pressure while the fast ram will see zero pressure. This provides a
very effective synchronizing means between the two rams and allows
use of a single feedback mechanism for the entire door system
thereby reducing the control system complexity and cost.
The coupled shafts 53 of the metering motors 51 and 52 are
connected to a gear reducer 54. A gear reducer is preferably used
since a practical and economical size of motor 51, 52 will make a
number of revolutions in delivering enough fluid to the ram to
fully open and close the doors. The small gear box is inserted to
thereby give an appropriate ratio whereby the output shaft 55 will
undergo approximately one revolution between fully open and fully
closed positions of the doors. As the metering motor turns, it will
drive the movable electrical tap 56 along the resistor 57 to vary
the electrical resistance 57a, 57b between the tap and the lines
58, 59, respectively. A slip clutch 60 is inserted in the output
shaft 55 and stops 61, 62 limit rotation of the shaft by abutting
the member 63 mounted for rotation with the shaft. Preferably, the
gear reducer is chosen to give slightly more than one full
revolution of the output shaft as the door goes from fully closed
to fully open.
The fixed stops 61, 62 are positioned so as to allow the shaft 55a
to make slightly less than one full revolution. In this way, any
tendency for the system to drift because of fluid leakage is
automatically corrected. For example, if the metering motor has
lagged in rotation in the "opening" direction, the output shaft
will lag in its position correspondingly. However, when the door
closes, the output shaft will attempt to turn back beyond its fixed
stop, i.e., past zero, because of the lag. When the output shaft
55a reaches its fixed stop, the slip clutch will operate allowing
the metering motor to continue to turn until the door finally
reaches its fully closed position. The output shaft and door are
thereby resynchronized and the drift error cancelled. Drift errors
in the opposite direction are cancelled by the equivalent action
when the door reaches its fully open position.
Correcting system drift errors by use of a slip clutch has the
effect of reducing the range of possible intermediate door opening
settings from 0--100 percent to about 5--95 percent. However, this
is no practical disadvantage in the heavy equipment industry.
Actually, system drift will be quite small in the usual case since
the metering motors ordinarily will have essentially zero pressure
drop across them with a corresponding reduction in slippage.
Furthermore, since the system corrects itself in each full cycle of
operation, very serious ram blowby, system leakage, etc., would
have to occur before serious positioning errors would occur. Normal
system repair and maintenance would preclude this degree of
hydraulic system degradation.
Another advantage of employing a slip clutch is to provide a
predetermined torque limit between the metering motor shaft and the
sensing means employed, thus allowing use of relatively small and
simple control devices such as the potentiometer described.
Referring again to the drawing, the resistor 57 forms two legs 57a,
57b of a bridge circuit. A potentiometer 66 including tap 67
defining resistor portions 66a and 66b between the tap 67 and lines
58 and 59 respectively forms another two legs of a bridge. A coil
68 is connected between the bridge terminals defined by taps 56 and
67. One bridge terminal 59 is grounded and voltage +V is applied to
the other bridge terminal. The coil 68 operates contactor 69 of a
polarized relay. The contactor connects the voltage +V to one or
the other of the contacts 71, 72, when the bridge is unbalanced.
When the bridge is balanced, contactor 69 remains in a center or
neutral position and neither contact 71 or 72 is energized.
With the control switch in the operator's location set to connect
the voltage +V to the line 58, the contactor 69 will contact either
contactor 71 or 72 to energize the corresponding solenoid 43 or 44
to operate the solenoid valve to supply fluid to the hydraulic
pistons until tap 56 is moved to bring the bridge into balance. The
position is controlled by moving tap 67, and the door can be made
to follow by moving the tap 67. Thus, by providing a setting
potentiometer in the operator's cab, he can continuously adjust the
intermediate door opening.
In order to close the doors, the operator connects the voltage
supply +V to line 76 energizing solenoid 74, causing the pistons to
move in the direction indicated by arrows 49. The doors are
maintained closed by the hydraulic pressure supplied to the pistons
via line 33. When the dumping area is reached, the operator
connects the voltage supply to line 58 and the doors open to the
position determined by setting of the tap 67. It is noted that the
operator can at this time control or move the doors by moving the
tap 67. When the load is discharged, the operator may switch back
to the closed position connecting the voltage supply to line 76 or
to the open position connecting the voltage to line 77 and
energizing solenoid 43 and causing the pistons to move in the
direction indicated by the arrows 47. This assures complete
discharge of the material. Thereafter, the operator switches to the
close position. The above sequence of operation from fully closed,
to intermediate, to fully open and back to fully closed is the
preferred operation since it will correct for drift errors in
either direction.
It is to be observed that the electrical control system and
metering motors can be located remote from the doors where they
will not be subjected to the rugged environment. The controls may
be as simple as a three-position switch and a potentiometer. Lamps
may be incorporated in the lines to give the operator a visual
indication of the cycle and the potentiometer can be calibrated to
indicate the intermediate door opening.
A full servosystem has been described; that is, a system in which
the operator can move the door in either direction when the switch
is in the intermediate position. By eliminating the contact 72, the
operator can only control the position to which the door opens.
Referring to Figure 6, there is shown a control system which
employs a switch 84 for controlling the valve 38 to stop the doors
at the intermediate point. In Figure 6, the same reference numerals
are applied to parts which correspond to those in Figure 5. The
sensor assembly shown in the dotted block 81 differs from the
sensor assembly previously described in that it includes a cam 82
mounted on the shaft 55a. The cam 82 is adapted to move the button
or plunger 83 which opens the normally closed switch 84. When the
operator's switch is set to apply voltage to the line 58, fluid
will be applied to the door rams 21, 22 to open the doors. When the
cam 82 strikes the button 84, the switch is opened to thereby
deenergize the valve solenoid. The valve returns to its neutral
position wherein the rams are held in the intermediate
position.
As before, operation of the switch by the operator to connect the
voltage +V to line 59 will actuate the rams to close the doors.
Adjustment of the intermediate position is affected by properly
setting the cam 82 relative to the position at the stop 63 on the
shaft 55a, or by moving the position of the stops 61, 62. The
control system in Figure 6 requires a mechanical adjustment.
However, the assembly is removed from the door position and can be
located in an easily accessible portion of the equipment. Thus,
adjustment can be easily accomplished. The system again includes
means with stops 61, 62 for compensating for leakage or drift.
A control system which is entirely hydraulic is shown in Figure 7.
A hydraulic motor is shown in place of a ram. A hydraulic pump 31a
supplies hydraulic fluid under pressure to the bypass valve 32a and
thence to the lines 33a and 37a. A valve 86 is connected in the
lines 33a and 37a. The valve is under the control of the operator
to be positioned in one of three positions. Three output lines are
associated with the valves. The line 87 provides fluid under
pressure to the motor 88 to cause rotation of shaft 89 to fully
close the associated door and maintain the same under pressure. The
line 91 is adapted to provide hydraulic fluid under pressure to the
motor to rotate the shaft 89 to fully open the associated door. The
fluid line 92 is connected to a metering motor 93 and thence
through a two-way valve 94 to join with line 91 and apply fluid
under pressure to drive the motor and rotate the shaft in an
opening direction to an intermediate position. A gear reduction box
96 is connected to the motor shaft and thence to a slip clutch 97.
A cam 98 is mounted on the output shaft 99 of the slip clutch and
is adapted to activate the two-way valve 94 by depressing the
plunger 101. A stop assembly including stops 102, 103 and member
104 affixed to the shaft serves to stop the rotation of the shaft
99.
In operation, to open the door from the closed position to the
intermediate position, the valve 86 is adjusted whereby the
connections between the lines 33a, 37a and 87, 91 and 92 are as
indicated at 106 wherein the pressure line 33a is connected to the
metering motor line 92 through the valve 94 to the motor 88. When
the cam 98 has rotated to depress the plunger 101, the valve 94
closes and motor rotation is stopped at the intermediate position
which is preset by adjustment of the cam 98.
To drive the motor to its extreme position, the valve 86 is
adjusted to the position 108 wherein the line 33a is connected to
the line 91 and the line 37a to the line 87.
Thereafter, to drive the motor to its other extreme position, the
three-way valve 86 is moved to the position indicated at 109
whereby pressure is applied to the motor along line 87 to rotate it
in the opposite direction. The lines 91, 92 are connected to the
return line 37a.
The control valve in the embodiment shown can be located at the
operator position. On the other hand, the complete hydraulic system
may operate through pilot lines which control hydraulic actuators
on the valve 86.
There has been provided a control system to remotely control
hydraulically actuated movable members. The control can be located
at a protected position. The system includes means whereby drift is
automatically compensated by operation of the control member
between two extreme positions. The control system is simple in
design and relatively easy to adjust to provide selected
intermediate positions for the movable, hydraulically operated
controlled members. The connections between the operator location
and the operating mechanism for the controlled member can be
electrical or hydraulic.
It is apparent that the invention is not to be limited to a
tractor-trailer combination but rather that it is applicable to
equipment which is remotely controlled to control hydraulically
actuated movable members to be selectively positioned.
* * * * *