U.S. patent number 3,884,040 [Application Number 05/335,544] was granted by the patent office on 1975-05-20 for hydraulic actuator.
This patent grant is currently assigned to Superior Iron Works & Supply Company, Inc.. Invention is credited to Lane A. Green.
United States Patent |
3,884,040 |
Green |
May 20, 1975 |
Hydraulic actuator
Abstract
A hydraulic actuator comprises a worm gear including a worm
supported for rotation by means of a handle and a worm wheel driven
by the worm. The worm wheel surrounds and drives a sleeve which is
threadedly engaged with the lead screw. A piston is supported on
one end of the lead screw for reciprocation thereby in response to
rotation of the worm. The piston is enclosed by the barrel of a
hydraulic cylinder, and upon reciprocation functions to cause
hydraulic fluid flow into and out of the cylinder. The worm gear
and the lead screw provide an overall mechanical advantage of about
40:1, so that substantial actuation of the handle is required in
order to provide even a relatively small output from the hydraulic
cylinder. The hydraulic cylinder is utilized in a line tensioning
machine of the type in which line from a supply reel is directed
around a bull wheel. A caliper-type disk brake is utilized to
control the rotation of the bull wheel and thereby regulates the
tension of the line as it is paid out from the machine. The disk
brake of the line tensioning machine is actuated by means of
hydraulic pressure supplied by the hydraulic actuator. The high
mechanical advantage afforded by the worm gear and the lead screw
of the hydraulic actuator facilitates precise control over the
braking force which is applied by the disk brake, which in turn
provides precise control over the tension of the line.
Inventors: |
Green; Lane A. (Shreveport,
LA) |
Assignee: |
Superior Iron Works & Supply
Company, Inc. (Shreveport, LA)
|
Family
ID: |
23312228 |
Appl.
No.: |
05/335,544 |
Filed: |
February 26, 1973 |
Current U.S.
Class: |
60/593; 60/534;
188/71.1; 188/353; 74/89.14; 188/83 |
Current CPC
Class: |
F16H
25/20 (20130101); F15B 7/08 (20130101); F15B
2015/1495 (20130101); F16H 2025/209 (20130101); Y10T
74/18792 (20150115) |
Current International
Class: |
F16H
25/20 (20060101); F15B 7/08 (20060101); F15B
7/00 (20060101); F15B 15/00 (20060101); F15B
15/14 (20060101); F15b 007/08 () |
Field of
Search: |
;91/31,32,33 ;188/353
;60/593,533 ;74/89.14,89.15 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Maslousky; Paul E.
Attorney, Agent or Firm: Hubbard, Thurman, Turner &
Tucker
Claims
What is claimed is:
1. A hydraulic actuator for facilitating precise control over an
apparatus to perform a function by means of the action of
pressurized hydraulic fluid outside said actuator which
comprises:
a housing with a hydraulic cylinder rigidly attached thereto, said
hydraulic cylinder including a piston mounted for relative
reciprocation to selectively cause hydraulic fluid flow to and from
the apparatus;
operator means; and
a mechanism having a relatively high mechanical advantage for
effecting relative reciprocation of the piston in response to
actuation of the operator means so that a relatively substantial
actuation of the operator means is required in order to effect a
relatively small change in the performance in the function by the
apparatus.
2. The hydraulic actuator according to claim 1 wherein the
mechanism for effecting reciprocation of the piston includes:
a lead screw operatively connected to the piston;
a member threadedly engaging the lead screw and supported for
rotation to extend and retract the lead screw and thereby effect
relative reciprocation of the piston; and
means responsive to actuation of the operator means for rotating
the member and thereby effecting a change in the performance of the
function by means of the lead screw, the hydraulic cylinder, and
the hydraulically actuated apparatus.
3. A hydraulic actuator actuating an apparatus outside said
actuator by means of pressurized hydraulic fluid comprising:
hydraulic cylinder means including piston means mounted for
relative reciprocation to cause hydraulic fluid flow into and out
of the cylinder means;
a lead screw operatively connected to the piston means to effect
actuation thereof;
a sleeve threadedly engaging the lead screw for rotation to cause
selective extension and retraction of the lead screw and thereby
effecting relative reciprocation of the piston means of the
hydraulic cylinder means;
a worm gear including a worm and a worm wheel mounted in mesh and
operatively connected to the sleeve to effect rotation thereof;
and
means for selectively rotating the worm of the worm gear and
thereby actuating the worm wheel, the sleeve, and the lead screw to
effect relative reciprocation of the piston means of the hydraulic
cylinder means.
4. The hydraulic actuator according to claim 3 further including
housing means enclosing the worm gear, the sleeve, and the lead
screw, wherein the hydraulic cylinder means further includes a
barrel enclosing the piston means which is mounted on and extends
from the housing, and wherein the piston of the hydraulic cylinder
means is mounted on the end of the lead screw.
5. A hydraulic actuator comprising:
a housing;
a shaft rotatably supported in the housing;
a handle secured to one end of the shaft for manual actuation to
rotate the shaft;
a worm mounted on the shaft for rotation by means of the
handle;
a sleeve rotatably supported in the housing;
a worm wheel supported by the sleeve and mounted in mesh with the
worm for rotation thereby;
said sleeve having an internally threaded portion concentric with
the worm wheel;
a lead screw threadedly engaged with the internally threaded
portion of the sleeve and mounted for reciprocation relative to the
housing in response to rotation of the worm by means of the
handle;
a hydraulic cylinder including a barrel secured to and extending
from the housing; and
a piston mounted on the lead screw and enclosed by the barrel for
reciprocation therein to cause hydraulic fluid flow into and out of
the cylinder hydraulically actuating an apparatus outside said
actuator.
6. A hydraulic actuator for facilitating precise control over an
apparatus to perform a function by means of the action of
pressurized hydraulic fluid outside said actuator which
comprises:
a hydraulic cylinder including a piston mounted for relative
reciprocation to selectively cause hydraulic fluid flow to and from
the apparatus;
a lead screw operatively connected to the piston;
a member threadedly engaging the lead screw and supported for
rotation to extend and retract the lead screw and thereby effect
relative reciprocation of the piston;
an operator means; and
means responsive to actuation of the operator means including a
worm wheel operatively connected to said member and a worm mounted
in mesh with said worm wheel, wherein the operator means is
effective upon actuation to rotate the worm and thereby cause a
change in the performance in the function of said apparatus by
means of the worm wheel, the member rotatable thereby, the lead
screw, the hydraulic cylinder and the hydraulically actuated
apparatus.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to a hydraulic actuator, and more
particularly to a hydraulic actuator which facilitates extremely
precise regulation of hydraulically driven apparatus.
In certain line tensioning machines, line is paid out from a supply
reel and is directed around a bull wheel. Caliper-type disk brakes
may be utilized to control the rotation of the bull wheel and
thereby regulate the tension that is applied to the line. Both
mechanical and hydraulic caliper actuation systems have been used
in line tensioning machines, however, none of the caliper actuation
systems provided heretofore has proven wholly satisfactory. For
example, most of the prior art hydraulic-type caliper actuating
systems have utilized hand pumps to provide the necessary hydraulic
pressure. This is unsatisfactory because hand pumps are incapable
of raising or lowering hydraulic pressure in fine increments, and
therefore do not afford precise control over the actuation of the
disk brake of a line tensioning machine. This has often
necessitated numerous readjustments of the caliper actuation system
of such a device in order to provide the exact tension that may be
required for a particular line tensioning operation.
The present invention relates to a hydraulic actuator which
facilitates extremely precise regulation of hydraulically driven
apparatus, and is therefore especially adapted for use in the
actuation of the caliper-type disk brakes of line tensioning
machines and in similar applications. In accordance with the
broader aspects of the invention, a hydraulic actuator includes a
hydraulic cylinder which is actuated by means of a mechanism having
a high mechanical advantage. This necessitates substantial
actuation of the mechanism in order to produce even a relatively
small output, and thereby facilitates very precise regulation of a
hydraulically driven apparatus which is operated by the
actuator.
In accordance with more specific aspects of the invention, the
hydraulic cylinder is actuated by a mechanism including a worm gear
and a lead screw. The overall mechanical advantage of the mechanism
is about 40:1, whereby extremely precise control over the output of
the cylinder is provided. Moreover, the worm gear is self-locking
whhich eliminates the necessity of providing auxiliary locking
mechanisms, check valves, etc. in order to maintain a desired
setting.
In accordance with still more specific aspects of the invention,
the worm gear includes a worm adapted for rotation by a handle or
similar actuator. The worm rotates a worm wheel which surrounds and
drives an internally threaded sleeve. The sleeve is threadedly
engaged with the lead screw, so that the lead screw is actuated
linearly in response to rotation of the worm. A piston is secured
to the lead screw for reciprocation thereby with respect to a
barrel comprising part of the hydraulic cylinder. By this means
very precise control over the positioning of the piston within the
barrel is provided, which in turn provides precise control over the
flow of hydraulic fluid into and out of the cylinder.
DESCRIPTION OF THE DRAWINGS
A more complete understanding of the invention may be had by
referring to the following Detailed Description when taken in
conjunction with the accompanying drawings, wherein:
FIG. 1 is a perspective view of a line tensioning machine utilizing
the invention;
FIG. 2 is a schematic illustration of various component parts
incorporated in the line tensioning machine shown in FIG. 1;
and
FIG. 3 is an illustration of a hydraulic actuator incorporating the
invention in which certain parts have been broken away more clearly
to illustrate certain features of the invention.
DETAILED DESCRIPTION
Referring now to the Drawings, and particularly to FIG. 1 thereof,
there is shown a line tensioning machine 10 utilizing the present
invention. The line tensioning machine 10 includes a frame 12
including a rear end supported by a pair of wheels 14. The front
end of the frame 12 is provided with a hitch 16, whereby the line
tensioning machine may be towed by a truck or other towing vehicle.
The front end of the frame 12 is supported by a conventional
landing gear 18 whenever it is not connected to the towing
vehicle.
The rear end of the line tensioning machine 10 further comprises a
reel spindle mechanism 20. The reel spindle mechanism 20 comprises
an axle 22 which supports a reel 24. The reel 24 carries a quantity
of line 26 which is paid out from the line tensioning machine 10 in
the direction indicated by the arrow 28.
The reel spindle mechanism 20 further includes a drum 30 supported
for rotation with the reel 24. A brake band 32 is connected to a
lead screw mechanism 34 by a chain 36. The lead screw mechanism 34
includes an operating handle 38 whereby the mechanism 34 may be
actuated to control the tension of the brake band 32. By this means
the brake band 32 and the drum 30 function to prevent over-running
of the reel 24.
The line 26 extends from the reel 24 around a bull wheel 40. The
function of the bull wheel 40 is to regulate the tension in the
line in accordance with the requirements of the particular
operation wherein the line is utilized. In the line tensioning
machine 10, this is accomplished by means of a hydraulically
actuated, caliper-type disk brake which regulates the rotation of
the bull wheel 40. The operation of the disk brake is in turn
controlled by a hydraulic actuator 42 incorporating the present
invention.
Referring now to FIG. 2, the bull wheel 40 is mounted on a shaft 44
which is rotatably supported on the frame 12 of the line tensioning
machine 10 by means of a pair of spaced apart bearings 46 and 48. A
caliper-type disk brake mechanism 50 includes a disk 52 mounted on
the shaft 44 for rotation with the bull wheel 40. A caliper
mechanism 54 includes a pair of brake pads 56 supported for
engagement with the disk 52 to regulate rotation of the shaft 44
and the bull wheel 40. The pads 56 are mounted on a pair of arms 58
which are pivotally interconnected by a shaft 60. The arms 58
biased outwardly by a spring 62 and are selectively drawn inwardly
against the action of the spring 62 by a hydraulic cylinder 64. By
this means the brake pads 56 are engaged with the disk 52 of the
caliper-type disk brake mechanism 50. It will be understood that
the disk brake mechanism shown in FIG. 2 is illustrative only, and
that any of the conventional disk brake mechanisms commonly
employed in line tensioning machines may be utilized in the
practice of the invention.
The hydraulic cylinder 64 of the caliper mechanism 54 is actuated
by means of hydraulic fluid supplied from the actuator 42 through a
conduit 66. As is best shown in FIG. 3, the hydraulic actuator 42
comprises a housing 70 which encloses a worm 72. The worm 72 is
mounted on a shaft 74 which is rotatably supported in the housing
70 by means of a pair of tapered roller bearings 76. As is best
shown in FIGS. 1 and 2, a handle 78 is secured to one end of the
shaft 74 for selective actuation to rotate the shaft and the worm
72.
The worm 72 is mounted in mesh with a worm wheel 80 and cooperates
therewith to form a worm gear having a mechanical advantage of
about 10:1. The worm wheel 80 is secured to a sleeve 82 which is
rotatably supported in the housing 70 by means of a pair of tapered
roller bearings 84. The sleeve 82 is internally threaded, and a
lead screw 86 is threadedly engaged with the sleeve 82. The lead
screw 86 is secured against rotation relative to the housing 70,
and has a pitch of about 0.25. Therefore, upon rotation of the
handle 78, the lead screw 86 is either advanced or retracted
relative to the housing 70 under an overall mechanical advantage of
about 40:1.
A sleeve 88 is threadedly secured to the bottom of the housing 70
of the hydraulic actuator 42, and extends downwardly therefrom. The
sleeve 88 merely serves to enclose and protect the lead screw 86
during retraction thereof relative to the housing 70. A cap 90 is
threadedly secured to the upper end of the housing 70 and serves to
support the upper tapered roller bearing 84. The cap 90 also
supports a barrel 91 which is threadedly received in the upper
portion of the cap.
The barrel 91 comprises part of a hydraulic cylinder 92 which
further includes a piston 94. The piston 94 is mounted for
reciprocation within the barrel 91 and includes an O-ring 96 or
other conventional packing means. The piston 94 is secured to the
lead screw 86 by means of a threaded extension 98 thereon. It will
therefore be understood that upon rotation of the handle 78, the
actuator 42 functions by means of the worm 72, the worm wheel 80,
the sleeve 82 and the lead screw 86 to reciprocate the piston 94 of
the hydraulic cylinder 92.
The blind end of the cylinder 92, the conduit 66 and the rod end of
the hydraulic cylinder 64 are all filled with hydraulic fluid.
Therefore, upon upward (FIG. 3) reciprocation of the piston 94,
hydraulic pressure within the cylinder 64 is increased, and the
pads 56 are drawn inwardly against the action of the spring 62 by
the cylinder 64. On the other hand, upon downward (FIG. 3)
reciprocation of the piston 94, the hydraulic pressure within the
rod end of the cylinder 64 is reduced, whereby the pads 56 are
permitted to move outwardly under the action of the spring 62. The
actuator 42 may be provided with a hydraulic pressure gauge 100
which is useful in regulating the operation of the actuator 42 and
hence the operation of the caliper-type disk brake 50.
Those skilled in the art will appreciate the fact that the use of
the present invention incorporates numerous advantages over the
prior art. Thus, by means of the invention, a hydraulic actuator is
adapted to facilitate extremely precise regulation of hydraulically
driven apparatus. This is highly advantageous in any apparatus
wherein very precise operational control is necessary or desirable.
For example, in a line tensioning mechanism, the hydraulic actuator
of the present invention may be utilized to afford precise control
over the braking force that is applied by a caliper-type disk brake
to a bull wheel. This in turn provides precise control over the
tension that is applied to a line being paid out from the line
tensioning machine.
A related advantage stemming from the use of the invention involves
the fact that in accordance with the embodiment thereof shown in
the drawings, the hydraulic actuator incorporates a hydraulic
cylinder which is actuated by means of a worm gear. As will be
appreciated by those skilled in the art, such a device is
substantially self-locking. Therefore, by means of the present
invention a hydraulically driven apparatus is not only regulated
with extreme precision, but is thereafter maintained in the
regulated condition without the necessity of additional locking
apparatus, check valves, or the like.
Although particular embodiments of the invention have been
illustrated in the accompanying drawings and described in the
foregoing Description, it will be understood that the invention is
not limited to the embodiments disclosed, but is capable of
numerous rearrangements, modifications, and substitutions of parts
and elements without departing from the spirit of the
invention.
* * * * *