U.S. patent number 3,705,631 [Application Number 05/147,514] was granted by the patent office on 1972-12-12 for hydraulic tilt and pitch control for dozer blade.
This patent grant is currently assigned to J. I. Case Company. Invention is credited to David H. Seaberg.
United States Patent |
3,705,631 |
Seaberg |
December 12, 1972 |
HYDRAULIC TILT AND PITCH CONTROL FOR DOZER BLADE
Abstract
A fluid control system for a load handling implement such as a
dozer blade carried by means of a universal joint on a load
handling machine which comprises a pair of double-acting fluid
cylinders having one end attached to the implement and the other
end to a stationary part of the machine; the pair of fluid
cylinders are each connected at opposite ends by a pair of fluid
lines to a source of fluid under pressure including a main control
valve and a selector valve; the main control valve and the selector
valve are actuated by a single control lever which when pivoted in
one direction positions the main control valve for tilting the
implement clockwise and if pivoted in the opposite direction
positions the main control valve for tilting the implement
counterclockwise; and the control lever is provided with an
actuator to condition the selector valve for pitching of the
implement in either forward or rearward inclination by actuation of
the control lever actuator coupled with pivotal movement of the
control lever in one or the other of the tilt-controlling
directions.
Inventors: |
Seaberg; David H. (Davenport,
IA) |
Assignee: |
J. I. Case Company (Racine,
WI)
|
Family
ID: |
22521878 |
Appl.
No.: |
05/147,514 |
Filed: |
May 27, 1971 |
Current U.S.
Class: |
172/812; 91/518;
91/520; 91/523; 91/526; 91/527; 91/531; 91/536; 172/821 |
Current CPC
Class: |
E02F
3/844 (20130101) |
Current International
Class: |
E02F
3/84 (20060101); E02F 3/76 (20060101); C02f
003/76 () |
Field of
Search: |
;172/801-809 ;91/411,413
;37/DIG.7,DIG.10 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pulfrey; Robert E.
Assistant Examiner: Pellegrino; Stephen C.
Claims
I claim:
1. In a fluid control system for an earth moving blade pivotally
supported on a vehicle for selectively varying the pitch and tilt
position of said blade relative to a ground surface, said blade
being pivoted around intersecting axes and said vehicle having a
control console, the improvement comprising:
first and second fluid cylinders, each having a piston and piston
rod and each having one end connected to opposite upper ends of
said blade and the other end to said vehicle;
a main control valve means connected to a source of fluid under
pressure and having first and second sections separate from each
other;
a selector valve movable by selector valve control means between a
pitch control and a tilt control position;
first and second conduits interconnecting the rear and front ends,
respectively, of said first cylinder with said selector valve, and
third and fourth conduits interconnecting the rear and front ends,
respectively, of said second cylinder with said selector valve;
first and second pairs of conduits interconnecting said first and
second sections, respectively, of said main control valve means
with said selector valve, each of said pairs including a supply and
an exhaust conduit, and said main control valve having reversing
means for simultaneously reversing the supply-exhaust functions of
said conduits within each conduit pair;
said selector valve, in its tilt position, providing communication
between said second and fourth conduits, between said first conduit
and the exhaust conduit of said second pair of conduits, and
between the supply conduit of said second pair of conduits and said
third conduit, all when said main control valve is in a first
position, to tilt the blade in a first direction, and the reversing
of the supply-exhaust functions of said second pair of conduits by
said main control valve reversing means causing the blade to tilt
in the opposite direction;
said selector valve, in its pitch position, providing communication
between said first and third conduits and the respective supply
conduits of said first and second pair of conduits, and further
providing communication between said second and fourth conduits and
the respective exhaust conduits of said first and second pair of
conduits, all when said main control valve is in a first position,
to pitch the blade in a first direction, and the reversing of the
supply-exhaust functions of said first and second pairs of conduits
by said main control valve reversing means causing the blade to
pitch in the opposite direction.
2. The control system of claim 1 wherein said main control valve
reversing means comprises a control lever connected to said first
and second sections of said main control valve, said control lever
being pivotally mounted on the control console for pivotal movement
in two intersecting planes, movement of said control lever in a
first of said planes controlling direction of blade tilt adjustment
when said selector valve is in its tilt position, and movement of
said control lever in said first plane controlling direction of
blade pitch adjustment when said selector valve is in its pitch
position.
3. The control system of claim 2 wherein said selector valve
control means comprises an independently controllable actuating
switch on said control lever operatively connected to said selector
valve to selectively shift it between its pitch and tilt
positions.
4. The control system of claim 1 wherein pilot-operated check
valves are provided in each of said first, second, third and fourth
conduits, each of said check valves functioning to prevent return
flow from the associated end of the respective fluid cylinder
towards said selector valve unless a positive fluid pressure is
applied from the selector valve to the opposite end of said
respective fluid cylinder associated with such check valve.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates in general to fluid pressure operated
load handling mechanisms and more in particular to earth moving
equipments such as dozers or the like and to an improved fluid
control for the load handling blade of a dozer.
In earth moving equipments such as scrapers, dozers and the like,
it is known to position and pivotally mount a load handling blade
forwardly of the tractive vehicle and to provide means to
selectively vary the pitch position of the blade relative to a
longitudinal axis of the equipment and further to selectively
vertically position the blade around a rotary axis disposed in a
plane containing the longitudinal axis of the earth moving
equipment.
It is well known that earth moving equipments of this character are
subject to considerable shock loads during operation and therefore
must be of extremely rugged construction. Thus, when the blade is
set at a desired pitch or tilt position, such as in forming a ditch
or leveling a road, the blade must be capable of maintaining the
position regardless of the hardness or composition of the material
being moved and regardless of the heavy thrust loads which the load
handling blade delivers back to the equipment.
Conventionally, the load handling blade is mounted on the earth
moving equipment by means of a central swivel joint, one part of
which is attached the rear of the blade and the companion part is
attached to the pusher frame of the earth moving equipment to
permit angular positioning of the blade around a vertical and
horizontal axis.
Normally, a pair of fluid cylinders are attached to the rear of the
blade and at both ends thereof having their other end attached to
the frame of the earth moving equipment, which, when selectively
actuated, vary the pitch angle of the blade by pivoting the blade
around a horizontal axis of the swivel joint relative to the
longitudinal axis of the equipment. Normally, to vary the vertical
position of the blade edgewise (tilting) a separate fluid motor has
been provided heretofore in addition to the fluid motors for
pitching of the blade, which has a separate control means for
selective actuation by the operator of the equipment.
This conventional arrangement requires multiple hydraulic control
means and multiple fluid power tubing carried by the earth moving
equipment increasing the difficulties in installation of hydraulic
power equipment and further increasing the maintenance of the fluid
power equipment and complicating the operation of the controls.
In accordance with the present invention, an improved hydraulic
control system for a load handling or earth moving blade, such as a
dozer blade, has been provided, which effectively eliminates the
above difficulties of the prior art by combining the hydraulic
control for tilting and pitching of the blade into a single
integrated hydraulic circuit operable by means of a single control
lever at the operator's control console.
Accordingly, a pair of hydraulic cylinders are provided connected
by conduits to a selector valve and from there to separate sections
of a main control valve. The two valve sections in the main control
valve are operated in synchronization by a linkage hooked up to the
single operator control lever. Synchronization of the two valve
sections is a function of spool position only and is affected only
slightly by pressure changes. Thus, when spool movements in the two
valve sections are synchronized the fluid flow delivery from these
two sections will be the same.
The selector valve has an actuator which is electrically connected
to a switch button on the single operating lever from the blade
pitching and tilting control. In the tilt position of the control
lever, the electrical switch for actuation of the selector valve is
open and fluid pressure, provided from the main control valve,
flows through the selector valve in a series circuit connection,
supplying fluid to diagonally opposite ends of the pair of
cylinders and exhausting fluid from diagonally opposite ends of the
pair of cylinders to thereby rotatably tilt the blade (either left
or right) around the swivel joint.
When it is desired to change the pitch angle of the blade, the
switch button on the single control lever is depressed which closes
the electrical circuit to thereby energize the valve actuator of
the selector valve, shifting the selector valve. This action
changes the previous hydraulic series circuit to a parallel circuit
in which fluid pressure is applied to directly opposite ends of the
double acting cylinders to thereby pitch the upper edge of the
blade around an axis transverse to the longitudinal axis of the
machine or equipment.
The fluid conduits of each of the pair of cylinders are connected
to pilot operated check valves operable in both directions of fluid
flow. The pilot operated check valves are used to provide locking
of the cylinders in place when the main control valve is not
supplying fluid and also prevents the cylinders from pulling away
from the pump when negative loads are encountered. This action is
accomplished by the check valves not allowing return flow from the
cylinders to the tank unless a positive pressure is applied at the
other end of the cylinders.
Both of the pairs of cylinders used for tilting and pitching of the
load handling blade, are identical having one end attached to the
rear of the blade and the other end secured to a part of the
equipment.
With the present arrangement pitching can be done after tilting of
the blade (or vice-versa), provided that one or the other cylinder
has not bottomed out to make further cylinder movement impossible.
Thus, if tilting of the blade is done first to the maximum position
in either direction, further operation of the hydraulic cylinder
for pitch positioning of the blade, will cause either an advance of
the other cylinder, which will change the tilt setting or retract
both cylinders and pitch back if the control is reversed. Thus,
pitching of the blade, after previous tilting of the blade, is best
done when the cylinders are between stops in either position so
that additional pitch adjustment will not influence the tilt
setting of the blade.
The present improved integrated hydraulic system to obtain both,
pitch angle tilt setting of the blade by means of the same pair of
hydraulic cylinders, considerably facilitates installation
requirements and maintainance of the hydraulic system of the
equipment by means of actuation of both pitch and tilt settings of
the blade by a single control lever. By this, a combination
operation is provided in which the operator of the equipment does
not have to move his hand from the control lever or to use another
hand or foot for operation of a separate control lever, as in
previous arrangements and thus, equipping the operator with more
freedom in the operation of the equipment which, as is known,
requires several hand or foot movements by the operator to
manipulate the many controls of the equipment.
The present invention will be best understood by reference to the
following detailed description of a preferred embodiment thereof,
described in connection with the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings schematically illustrate a preferred
embodiment of the invention in which:
FIG. 1 is a schematic illustration of the hydraulic system of the
present invention with associated hydraulic components being
indicated in dot and dash lines and shown in position for
tilting;
FIG. 1a shows the hydraulic system of FIG. 1 in position for
pitching of the blade;
FIG. 2 is a schematic side view of the blade of the equipment being
operated by the system of FIG. 1 with various pitch positions of
the blade being indicated in dot and dash lines;
FIG. 3 is a schematic front elevation of the blade of the equipment
in which the various tilt positions of the blade are indicated in
dot and dash lines; and
FIG. 4 is a schematic illustration of a representative control
arrangement at the operators control console of the equipment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With continuing reference to the attached drawings, the earth
moving blade 10 is centrally attached by means of an universal
swivel joint indicated at 12, to the front end of a tractive earth
moving or load handling machine, such as schematically indicated at
14 in FIG. 4.
The universal swivel joint 12 is preferably of the ball and socket
type so as to permit universal movement of the blade 10 at least
around two intersecting axis and in both directions of
rotation.
Generally, the blade 10 is conventionally connected to a pair of
opposite lift cylinders 16 and 18 respectively, for raising or
lowering of the blade relative to the ground surface and both of
which are connected by conduits to a valve section 20 of a main
control valve 22 which is in fluid communication with a pump 24 and
a source of fluid under pressure indicated at 26. The blade 10
additionally may be connected in conventional manner to a pair of
opposite angling cylinders 28 and 30 respectively for angling of
the blade relative to the longitudinal axis of the machine, as is
commonly known. Both angling cylinders 28 and 30 are likewise
connected by conduits to another valve section 32 of the same main
control valve 22 of the machine.
These arrangements are conventional, as for instance disclosed in
U.S. Pat. No. 2,943,407 to E.B. Long, and do not form a part of the
present invention.
In accordance with the present invention, the rear of the dozer
blade 10 is pivotally attached to one end of a pair of combined
tilt and pitch cylinders 34 and 36 respectively, at pivot points 38
and 40 near the opposite upper and outer edges of the blade 10. The
opposite ends of the pitch and tilt cylinders 34 and 36, which
define reciprocating piston rods 42 and 44 respectively, are each
pivotally connected at opposite universal and transversely aligned
pivot points 46 and 48 to a stationary part of the machine,
indicated at 14. Both pair of pivot points 38 and 40 and 46 and 48
are each transversely aligned on parallel horizontal axis normal to
the longitudinal axis "X" of the machine, which extends through the
center of the swivel joint 12 of the blade, for equalized force
distribution at either end of the blade during pitch or tilt
actuation of the cylinders 34 and 36.
The cylinder 34 has a front end chamber 50 which is connected by a
fluid conduit 52 via a one-way check valve 54 to a selector valve
56. The rear chamber 58 of the cylinder 34 is connected by means of
fluid conduit 60 via a one-way check valve 62 likewise to the
selector valve 56. The selector valve 56 is connected by a first
pair of fluid conduits 64 and 66 respectively to a separate valve
section 68 of the main control valve 22. The pair of one-way check
valves 54 and 62 and fluid conduits 52 and 60, respectively, are
connected by pilot lines 58 and 61, respectively, to the respective
opposite conduit for a purpose to be explained furtheron.
The opposite fluid cylinder 36 is likewise provided with a front
end chamber 70 which is in communication by means of a fluid
conduit 72 via one-way check valve 74 with another end of the
selector valve 56.
The rear chamber 76 of the fluid cylinder 36 is similarly connected
by a fluid conduit 78 via a similar check valve 80 to the selector
valve 56. The pair of check valves 74 and 80 are similarly
interconnected by pilot lines 75 and 81 respectively to be pilot
operated for a purpose to be described hereafter.
The section of the selector valve 56 connected by conduits 72 and
78 to the fluid cylinder 36 is connected by a pair of conduits 82
and 84 respectively to another separate section 86 of the main
control valve 22 for operation independent of the valve section
68.
The main control valve 22 is a directional flow compensating valve
such, that the flow rate of any spool in the separate sections
provide a rigidly fixed quantity completely independent of flow
changes. The valve is generally of conventional construction and
may be of the type of directional control valve such as
manufactured by the Warner-Motive Division of Borg-Warner
Corporation, Auburn, Ind. or Hydraulic Industries, Hartland,
Wisconsin, to provide equalized flow to the two cylinders 34 and 36
during pitching operation. Controlled fluid flow from the two valve
sections, operating from one pump, will be synchronized when the
total flow requirement is less than pump output.
Each of the valve sections 68 and 86 is provided with a
reciprocable actuator stem 88 and 90, respectively, which are
synchronized for operation by connection to a common pivot lever 92
which in turn is connected to the control lever 94 of the machine
positioned at the operator's control console 96, as shown in FIG.
4.
With continued additional reference to FIG. 4, when the control
lever 94 is rocked within a plane defined by the arrow "T" and in a
direction towards the letter "R", the tilt adjustment of the blade
10 is initiated to cause edgewise rotation of the blade around the
swivel joint 12 in a manner as schematically illustrated in FIG. 3.
By rocking the control lever 94 towards the direction "R", fluid
pressure is introduced through valve section 86 into fluid line 84,
through the selector valve 56, into fluid conduit 78, and through
one-way check valve 80 into the rear chamber 76 of the cylinder 36,
as indicated by the arrows in FIG. 1. Fluid pressure build-up in
the rear chamber 76 of the cylinder 36 causes relative
cylinder-piston movement and, since the cylinder is secured to the
blade 10 at point 40 and the piston rod to the machine 14 at point
48, the blade 10 is caused to rotate edgewise around the swivel
joint 12 in a manner illustrated in FIG. 3.
Relative cylinder-piston movement of cylinder 36 reduces the volume
of the respective front end chamber 70, causing fluid to be
displaced therefrom through conduit 72, check valve 74 and into the
selector valve 56, as indicated by the direction of the arrows.
Fluid, displaced from the chamber 70, passes longitudinally through
the valve 56 into the opposite conduit 52 and through check valve
54 into the front end chamber 50 of the opposite cylinder assembly
74 at the opposite end of the blade 10. Thus, relative pressure
build-up in the front end chamber 50 of cylinder 34 due to the
reduced fluid volume in the front end chamber 70 of the opposite
cylinder 36 at a directly proportional magnitude thereto, causes
similar piston-cylinder movement of cylinder 34 in an opposite
direction to that of cylinder 36 in correspondence with the
direction of rotation of the blade 10 around the swivel joint 12.
Relative piston-cylinder movement of the cylinder assembly 34 due
to an increase in fluid pressure in the front end chamber 50 causes
the fluid volume to be reduced in the rear end chamber 58 forcing
fluid out through the conduit 60 and through the check valve 62
into the selector valve 56, as likewise indicated by the direction
of the arrows. The return flow of fluid from the lower chamber 58
of the cylinder assembly 34 passes through the selector valve 56 in
linear direction and through the conduit 82 back into the main
control valve section 86 for return flow through the conduit 25
back into the reservoir 26.
If the control lever 94 is rocked in the opposite direction along
the arrow "T" towards the letter "L", the main valve section 86
will be actuated to supply fluid pressure to line 82 and exhaust
line 84. This reverses the direction of actuation of cylinder
assemblies 34 and 36 to cause rotational pivoting of the blade 10
around the swivel joint 12 in the opposite direction.
Thus, it will be understood that, when one cylinder assembly is
extended the other cylinder assembly is contracted a similar
amount, due to direct fluid pressure connection between opposite
chambers of the two cylinders, which cause proportional fluid
pressure being applied to opposite sides of the respective pistons
of the cylinders.
Each pair of pilot operated check valves 62, 54 and 74, 80, upon
actuation of either cylinder 34 or 36, is operational to lock both
cylinders in their respective adjusted position after further
supply of fluid pressure from the main control valve 22 is
interrupted. The pilot operated check valves also function in
inoperative position of the cylinders 34 and 36, to prevent return
flow from the cylinders to the reservoir unless a positive pressure
is applied at the other end of the cylinders.
The pilot operated check valves 62,54 and 74,80 are commercially
available items and may be of the type as those manufactured by the
Parker Hydraulics Division, Parker-Hannifin Corporation, Cleveland,
Ohio, under their model no. VCPD10.
In the above described tilt operation of the present improved
hydraulic system, the selector valve 56 remains in an inactive
position, such as to provide unobstructive fluid flow through the
valve in the manner indicated by the direction of the arrow along
the respective fluid lines in FIG. 1.
With further reference now to FIG. 1a and 2 in the drawings, these
FIGS. schematically illustrate the position of the improved
hydraulic system for varying the pitch angle of the blade 10 around
the universal swivel joint 12 in a direction of rotation, as
indicated in FIG. 2, around an axis of the universal swivel joint
which intersects the tilt axis of the swivel joint at a 90.degree.
angle.
WIth additional reference to FIG. 4, the selector valve 56 is
provided with actuator 100 which may be a solenoid suitably
connected by conduit 102 to ground and by conduit 104 to a source
of current 106, which may be the battery of the machine in which
the present improved system is embodied. Conduit 104 includes
switch 108 normally retained in open position and having switch arm
110 suitably connected for actuation to push button 112
conveniently disposed within or on control lever 94 (FIG. 4) for
selective manual actuation of switch 108.
In order to change the pitch angle of the blade as schematically
shown in FIG. 2, the operator depresses switch button 112 on
control lever 94 which energizes the solenoid circuit to close
switch 108 and actuate solenoid 100 to shift selector valve 56 to
the alternate position shown in FIG. 1a. Movement of control lever
94 in the "T" plane, that is, the same plane which controls tilt
when button 112 has not been actuated, will selectively raise or
lower the edge of blade 10 relative to the ground, as indicated in
FIG. 2. Thus, movement of control lever 94 in the direction towards
the letter "R" will supply fluid pressure from main control valve
22 simultaneously to both valve sections 68 and 86 at a
synchronized fluid flow, as previously explained in the description
of the main control valve. Thus, fluid flow at an even pressure is
transmitted through opposite fluid conduits 64 and 84 into selector
valve 56, which is in the new position shown in FIG. 1a. From the
selector valve 56, fluid pressure is delivered through conduits 60
and 78 and through the respective pilot operated check valves 62
and 80, into rear chambers 58 and 76 of cylinders 34 and 36. The
equalized fluid pressure in rear chambers 58 and 76 causes
simultaneous relative cylinder-piston movement at both cylinders in
a direction to draw the upper edge of blade 10 rearwardly around
swivel joint 12 to angularly reposition the lower cutting edge of
the blade, as shown in FIG. 2. Simultaneous relative
cylinder-piston movement causes a decrease in fluid volume in front
end chambers 50 and 70 of respective cylinders 34 and 36, forcing
fluid out through conduits 52 and 72 and through check valves 54
and 74, respectively, and selector valve 56 and from there back
into main control valve 22 through conduits 66 and 82,
respectively, for return to fluid reservoir 26.
The two pairs of pilot operated check valves 54, 62 and 74, 80, in
this mode of operation, similarly function to lock the cylinders in
place when main control valve 22 stops supplying fluid pressure to
the cylinders, thereby positively retaining the blade 10 in the
adjusted pitch position.
To pitch blade 10 in the forward direction, control lever 94 is
moved along the arrow line "T" in the opposite direction, towards
the letter "L" with switch button 112 depressed, reversing the
fluid flow through the conduits to apply positive fluid pressure to
front ends 50 and 70 of respective cylinders 34 and 36.
In order to obtain controlled pitch angle positioning of the blade
10, it is necessary that fluid pressure is supplied to both
cylinders simultaneously and at the same magnitude to prevent
twisting of the blade around swivel joint 12, which is herein
provided for by synchronized actuation of both valve sections 68
and 86 of main control valve 22.
The present invention thus provides both pitching and tilting of
the blade by the same pair of cylinders, this being controlled by
movement of control lever 94 in only a single plane, the "T" plane.
The "P" plane is reserved for lifting and lowering of the blade by
cylinders 16 and 18. Both pitching and tilting of the blade can be
accomplished so that pitching can be done after tilt movement of
the blade, or vise-versa, providing that neither of cylinders 34 or
36 has bottomed out in the previous pitch or tilt operation. Thus,
pitch adjustments after tilting or tilt adjustments after pitching,
when the cylinders are between stops, will not affect the previous
tilt or pitch angle setting of the blade. If one of the cylinder
has previously reached a stop, subsequent adjustment in the other
mode of movement will change the setting of the first mode, or, if
main control valve 22 is reversed, will eliminate non-neutral
positioning in the first mode.
Although the selector valve actuator means has been described
herein as a solenoid and electrical circuit operable by a manual
switch means, it will be appreciated that any other known
conventional, mechanical or fluid operated valve actuating
mechanism may be employed to the same advantage, although the
present solenoid actuated embodiment is preferred for convenience
and quick acting response.
It will be obvious from the foregoing description in conjunction
with appended drawings, that the present invention provides an
improved hydraulic control system for a load handling implement and
particularly for repositioning the blade of a dozer in directions
around two intersecting axes.
The present improved system employs only a pair of identical
cylinders for combined pitch and tilt angle positioning of the
blade, utilizing the same hydraulic circuit in both operations by
incorporation of a selectively repositionable selector valve
disposed between the main control valve and the pair of cylinders.
This improved arrangement greatly facilitates installation
requirements and maintenance of the fluid power equipment of the
dozer and at the same time greatly facilitates the handling of the
equipment by the operator of the machine by the provision of only a
single control lever utilized for both pitching and tilting of the
blade.
The selected angular position of the blade is positively locked in
place by provision of pilot operated check valves in the hydraulic
circuit between the selector valve and the pair of cylinders, to
prevent return flow of fluid from one end of the cylinders if no
positive pressure is present at the other end of the cylinders. The
function of the check valves at the same time reduce blade drift
and prevent the cylinders from pulling away from the pump when
negative loads are encountered.
Although the present invention has been described for illustrating
purpose by means of a schematically illustrated embodiment, it will
be obvious that various changes in structure, arrangement and
details may be made without departing from the spirit and essential
characteristic of the invention as defined by the scope of the
appended claims.
* * * * *