US3143338A

US3143338A - Hydraulic-pneumatic power assist apparatus

Info

Publication number: US3143338A
Application number: US121773A
Authority: US
Inventors: Jr Homer S Hoard
Original assignee: Philco Ford Corp
Current assignee: Space Systems Loral LLC
Priority date: 1961-07-03
Filing date: 1961-07-03
Publication date: 1964-08-04
Anticipated expiration: 1981-08-04

Description

Aug. 4, 1964 H. s. HOARD, JR

HYDRAULIC-PNEUMATIC POWER ASSIST APPARATUS Filed July 3, 1961 INVENTOR.

HOMER .s. Ha/mw, .rx.

Fla. 2. (PR/0.? ART) 5% lie.

United States Patent M 3,143,338 HYDRAULIC-PNEUMATIC POWER ASSIST APPARATUS Homer S. Hoard, 513, San Jose, Calif assignor, by mesne assignments, to Philco Corporation, Philadelphia, Pa.,

a corporation of Deiaware Filed .lnly 3, 1961, Ser. No. 121,773 6 Claims. (G. 267-1) This invention relates to hydraulic-pneumatic power assist apparatus, and more particularly to counter-balancing means embodying a hydraulic-pneumatic linkage system.

Mechanical linkage systems adapted to move relatively large objects normally are provided with counterbalance means comprising a large mass of material, such for example as metal or concrete, so arranged as to provide the desired balancing forces for the linkage system. A large mass of this type often represents a large static load which also must be supported by the base structure of the linkage system. Additional static loading due to the counterbalancing mass requires of course that the base structure be reinforced, which requirement involves increased materials, costs, and the like.

It is therefore a broad objective of this invention to provide a simple and effective counterbalancing means for a mechanical linkage system eliminating the need for a counterbalancing mass.

It is a specific object of the invention to provide novel counterbalancing force producing apparatus.

It is a more specific objective of the invention to provide a hydro-pneumatic system in combination with a four-bar linkage in place of a counterbalancing mass.

In achievement of the foregoing and other objectives the invention contemplates provision of counterbalancing means for a mechanical linkage system for driving a large unbalanced mass, comprising, in a preferred embodiment: cylinder means having a piston working therein, said piston including piston rod means projecting from one end of the cylinder, one of said means being attached to movable structure including a relatively large mass and the other of said means being attached to stationary structure, said cylinder having a single port in the region of one end and a pair of ports in the region of the other end, each said port accommodating movement of fluid to and from the cylinder as the piston moves therein; fluid supply means associated with said single port; a pair of fluid conduit means associated with said pair of cylinder ports; accumulator means disposed in fluid flow communication with each of said conduit means of said pair; pressure compensated flow control valve means disposed in one of said conduit means; and normally closed pressure relief valve means disposed in the other of said conduit means and operative to open in response to an increase of pres sure in said cylinder and said one conduit means.

It is a feature of the invention that the piston is disposed and adapted to close the port communicating with said conduit means in which the pressure compensated flow control valve means is disposed, as it moves toward the other port.

By virtue of the foregoing novel combination of flow control valve means and pressure relief valve means with the accumulator and cylinder there is achieved both a counterbalancing and snubbing action for the large mass and its related mechanical linkage system.

The foregoing as well as other objects and advantages will best be understood from a consideration of the following description, taken in light of the accompanying drawing in which:

FIGURE 1 is an elevational view of parabolic antenna apparatus embodying counterbalancing means made in accordance with the invention;

3,143,338 Patented Aug. 4, 1964 FIGURE 2 is a view similar to FIGURE 1, but illustrating counterbalancing means heretofore known in the art; and

FIGURE 3 is a somewhat diagrammatic showing of hydraulic-pneumatic counterbalancing means embodying the invention, a portion of which means is seen also in FIGURE 1.

With more particular reference to the drawing, and first to FIGURE 1, the'invention is depicted for exemplary purposes as being embodied in a relatively large parabolic antenna structure of a type currently used in the tracking of guided missiles, earth satellites, and the like. It Will be understood, however, that counterbalancing means embodying the invention also has utility in combination with crane, elevator, or other large machine structures requiring balanced linkage systems.

The aforementioned antenna structure comprises a tower or base 10 erected upon the ground G and including rotatable carriage 19 and gimbal means 11 that pivotally and rotatably mount a parabolic antenna 12. While it is to be understood that gimbal means 11 and carriage 19 provide 3-dimensional movement of antenna 12, the present detailed description will be made with respect only to Z-dimensional movement of the antenna, since principles of the invention can readily be understood by way of such simplified showing.

Making reference also to the diagrammatic showing of FIGURE 3, it is seen that carriage 19 for the antenna comprising the mass to be balanced and which is shown for convenience at 12 as a concentrated mass, comprises journal means 13 for antenna mounting shaft 14. Gimbal means 11 includes antenna support 18 carried, intermediate end portions thereof by shaft 14. A motor 34 (FIG- URE 3) is disposed and adapted to drive shaft 14, rotatably to position the latter and antenna 12 through movements of gimbal means 11 at elevations in accordance with the directional arrows applied thereto. It will be understod that azimuthal positioning of the antenna is achieved by rotating, through suitable drive means, carriage 19 about a vertical axis and with respect to base 10.

In particular accordance with the invention, counterbalancing means 15 comprises cylinder means 16 having a piston 17 working therein. Piston 17 includes a piston rod 21 projecting from one end of cylinder means 16 and pivotally attached at 22 to antenna support 18, and the end 23 of cylinder means 16 is pivotally attached at 24 to carriage 19. The construction and arrangement of the counterbalancing means 15 as thus far described is such that

pivotal attachments

22 and 24 of rod 21 and cylinder means 16, respectively, interconnect carriage 19 with antenna supporting gimbal means 11. It will also be noted that carriage 19, support 18, piston 17 with rod 21, and cylinder means 16 comprise the equivalent of a four bar linkage. Cylinder means 16 includes, in the region of its end 23, a single opening or port 28 connected by a flexible conduit 25 to means defining a supply of low pressure fluid designated generally by the numeral 26. It is the purpose of the fluid supply means 26 to maintain the presence of fluid in the lower portion of cylinder 16 and sealing ring 20 precludes leakage of fluid across piston 17.

The other end of cylinder means 16 includes a pair of openings or

ports

27 and 31 connected to

flexible conduits

32 and 33, respectively. It will be further noted that piston 17 includes a cylindrical projection 17a at its rod end. This projection 17a is receivable within restricted portion 16a of cylinder means 16, through which portion port 27 extends. Note that port 31 extends through a wall of cylinder means 16 just ahead of port 27 and restricted portion 16a, as respects upward movement of piston 16. The construction and arrangement of the piston 17, cylinder means 16, and

ports

27, 31

is such that as the piston moves upwardly from the broken-line showing thereof, in the direction of the solid directional arrow, the projection 17a will first enter por- .tion 16a to close port 27, leaving port 31 open. Continued upward movement of piston 17 causes its main body portion then to halt just short of closing port 31, as illustrated "in the full-line showing of the piston. As will be understood from what follows, this closing of port 27 activates means which provides a snubbing action for the antenna, which action is characterized by a low antenna deceleration value as it moves to a limit of its travel.

Conduit 32 is disposed in fluid flow communication with a pressure compensated fluid flow control valve 35 having an inlet port 36-and an outlet port 37. The valve additionally comprises a valve plunger or spool 41 having a variable fluid flow regulating portion 42 movable transversely of valve bore or conduit 43. One end of plunger 41 comprises a piston 40 that slides within a relativelysmall cylinder 44 ported through line 45 to valve conduit 43 at a region downstream with respect to plunger flow regulating portion 42. The other end of plunger 41 comprises a relatively large spring-loaded piston 46 that slides within a cylinder 47 that is ported, through a line 51, to valve conduit 43 at a region downstream of the porting of line 45 thereto. A restrictor having a preselected flow rate is disposed at 43a intermediate the connection of

lines

45 and 51 to conduit 43. The outlet port 37 of valve 35 is connected to a hydraulic-pneumatic accumulator 52 of known construction by means ofa conduit53.

Conduit 33 leads to and is disposed in fluid flow communication with a pressure relief valve 54, comprising a cylinder 55 having an inlet port 56 in one end thereof and an outlet port 57 in a side wall portion thereof. A piston 61 is slidable within cylinder 55 and is springloaded normally to maintain outlet port 57 closed, as shown, which port 57 is connected to accumulator 52 by

conduits

62 and 53. A check valve 63 is disposed in a conduit 64 interconnecting

conduits

33 and 53 as shown.

In the operation of the above described apparatus, in which connection movements first to be described are indicated by unbroken arrows, and considering that motor 34 has been energized to move antenna 12 in a clockwise direction upon rotatable shaft 14, piston 17 moves toward

openings

27 and 31 and fluid is caused to flow through conduit 32, valve 35, and conduit 53 into accumulator 52. As fluid moves into the accumulator gas contained therein, nitrogen for example, is compressed and stores energy in accordance with the degree of compression. This stored energy is utilizable later, to exert a counterbalancing force when the antenna is moved in the opposite direction as will be hereinafter described. Fluid does not flow at this stage through conduit 33 due to the fact that both check valve 63 and relief valve 54 are closed. Any tendencies to increased speed, due for example to effects of wind or variations in the speed of drive motor 34, are compensated for by the differential action of fluid pressure forces on

pistons

46 and 41 which regulate the position of fluid flow regulating plunger portion 42.

Valve 35, according to known practice, maintains its fluid flow setting regardless of the changing load on the fluid. The metering orifice or restrictor 43a is preselected for the required fluid flow rate, and compensator spool 41 operates to maintain a fixed pressure across the metering restrictor 43a'for a wide range of pressure loading.

The increased force required of piston 17 due to the increase in angle with the vertical to counter the moment of force exerted by the vertically directed center of gravity of the antenna 12, as its center of gravity moves closer to the horizontal, is compensated for, or counterbalanced, by the increased compression of gaseous fluid within accumulator 52. As the illustrated full clockwise positioning of antenna 12 is reached, at which time piston 17 has moved upwardly from the broken line showing,

the small portion 17a of piston 17 is caused to enter restricted portion 16a of cylinder 16 and thereby seals port 27 from the larger diameter cylinder. This closure immediately creates a pressure increase in cylinder 16, forcing fluid through port 31 and conduit 33 (wavy arrows), into cylinder 55 of relief valve 54, against the reactive force of its compression spring 540. The increased pressure achieves the desired decelerative snubbing force for the antenna as it moves to the end of its downward travel. As spring 54a is compressed further, piston 61 moves to uncover port 57 to permit fluid flow therethrough (wavy arrow) and again to subject the piston 17 to the pressure built up within the accumulator 52.

. Upon energizing motor 34 to elevate antenna 12, by moving the same in a counter-clockwise direction, piston 17 moves in the opposite direction (dotted arrow) whereupon the pressure is relieved within relief valve 54 and it again is closed (dotted arrow), unrestricted flow of fluid from the accumulator 52 to cylinder 16 taking place through check valve 63, until such time port 27 is opened by the unseating of piston portion 17a from cylinder portion 16a. Unrestricted return fluid flow (dotted arrows) then continues, such flow being effected by expansion of the gas within the accumulator 52, through check valve 63 and conduit 33, some return flow taking place through valve 35 and conduit 32. Concurrent with the flow of fluid into the upper end of cylinder 16 there is a flow of fluid from its lower end through opening 28 and fluid conduit 25 to low pressure fluid supply reservoir 26. It is this expansion of the gas in the accumulator that furnishes the counterbalancing force for the linkage system, which force is transmitted by the fluid to piston 17.

In contrast with the above disclosed invention, typical prior art counterbalance means for antenna 12a, as shown in FIGURE 2, comprises a steel-encased lead weight 15a mounted upon antenna support 18a the latter being pivotally mounted at 14a upon carriage 1911. This weight 15a of course constitutes an undesirable static load upon tower structure 19a and also presents an undesirable wind resistancesurface, which disadvantageous loading is overcome by the present invention. Furthermore, there is required in this apparatus a separate snubbing means operative independently of the counterbalancing lead weight 1511.

From the foregoing description it will be appreciated that the invention achieves, in a unitary hydro-pneumatic system not only a uniform counterbflancing action, but also a snubbing or damping action which in the disclosed apparatus advantageously prevents undue stressing of the antenna as would occur if the latter struck the tower structure due to excessive velocity and consequent excursion of antenna movement.

I claim:

1. In combination, a massive structure, support means for said structure, means defining a pivot for mounting said structure upon said support means with its center of gravity to one side of said support means and providing for pivotal movements of its center of gravity within predetermined upper and lower fixed limits to said one side of said support means, motor means for effecting such pivotal movements, a fluid cylinder, a piston movable within said cylinder and including rod means extending from an end thereof, said cylinder and piston comprising linkagemeans extending between and pivotally connected to said support means and to a portion of said massive structure disposed to the side of said pivot for mounting said structure opposite its center of gravity, said piston and cylinder thereby being pivotal as a unit relative to said support means and to said massive structure as it is moved about its pivot, accumulator means for storing fluid under pressure, and conduit means connected to said accumulator means and said cylinder toward the end thereof from which said rod means extends, fluid under pressure within said accumulator means thereby being ef fective to exert forces upon said piston for statically counterbalancing said massive structure as its center of gravity is moved about its pivot.

2. The combination according to claim 1, and characterized in that said cylinder is pivotally connected to said support means and said rod means is pivotally connected to said massive structure.

3. The combination according to claim 1, and characterized in that said fluid is a liquid and said accumulator means is of the hydraulic-pneumatic type.

4. In combination, a massive structure, support means for said structure, means defining a pivot for mounting said structure upon said support means with its center of gravity to one side of said support means and providing for movement of its center of gravity to said one side of said support means within predetermined upper and lower fixed limits, motor means for eflecting such pivotal movements, hydraulic cylinder and piston means pivotally interconnecting said support means and a region of said massive structure disposed to the side of said pivot for mounting the latter opposite its center of gravity, first and second conduits connected to said cylinder, said first conduit being disposed and adapted for closure by said piston means as it is caused to move toward the connection of said conduits to said cylinder upon pivotal movements of said massive structure to its lower limit by said motor means, hydraulic-pneumatic accumulator means connected to said conduits and providing fluid forces for statically counterbalancing said massive structure as its center of gravity is moved about its pivot, fluid flow control valve means disposed in said first conduit and restricting flow of fluid between said accumulator means and said cylinder as said massive structure is moved toward its lower limit, check valve means operative to by-pass said control valve means and permit unrestricted fluid flow between said accumulator means and said cylinder when said massive structure is pivoted toward its upper limit, and a fluid pressure relief valve disposed in said second conduit adapted to accommodate sudden excessive increases in fluid pressure in said cylinder, said massive structure being counterbalanced in any of its positions by forces imparted thereto by compressed fluid in said cylinder reacting against said piston throughout such pivotal movements.

5. In combination, a massive structure, support means for said structure, means defining a pivot for mounting said structure upon said support means with its center of gravity to one side of said support means and providing for pivotal movement of its center of gravity within predetermined fixed limits to said one side of said support means, motor means for eflecting such pivotal movemerits, a hydraulic cylinder, means pivotally linking said cylinder to said support means, a piston movable within said hydraulic cylinder and including rod means extending from an end thereof, means pivotally linking said rod means to a region of said massive structure disposed to the side of said pivot for mounting said structure opposite its center of gravity, said piston and cylinder thereby being pivotable as a unit relative to said support means and said massive structure as it is moved about its pivot, conduit means connected to said cylinder toward the end thereof from which said rod means extends, and hydraulic-pneumatic accumulator means connected to said conduit means and operative to exert hydraulic forces upon said piston thereby statically counterbalancing said massive structure as its center of gravity is moved about its pivot.

6. In combination, a massive structure, support means for said structure, means defining a pivot for mounting said structure upon said support means with its center of gravity to one side of said support means and providing for pivotal movements of its center of gravity within predetermined upper and lower fixed limits to said one side of said support means, motor means for eflecting such pivotal movements, a fluid cylinder, a piston movable within said cylinder and including rod means extending from an end thereof, said cylinder and piston comprising linkage means extending between and pivotally connected to said support means and to a portion of said massive structure spaced from said pivot for mounting said structure, said piston and cylinder thereby being pivotal as a unit relative to said support means and to said massive structure as it is moved about its pivot, accumulator means for storing fluid under pressure, and conduit means connected to said accumulator means and said cylinder toward the end thereof from which said rod means extends, fluid under pressure within said accumulator means thereby being effective to exert forces upon said piston for statically counterbalancing said massive structure as its center of gravity is moved about its pivot.

References Cited in the file of this patent UNITED STATES PATENTS 840,877 Steedman Jan. 8, 1907 1,821,787 Black Sept. 1, 1931 1,829,643 Cannon Oct. 20, 1931 2,001,988 Temple May 21, 1935 2,704,996 Peterson et al Mar. 29, 1955 2,719,510 Elder Oct. 4, 1955 2,783,742 Shafer Mar. 5, 1957

Claims

5. IN COMBINATION, A MASSIVE STRUCTURE, SUPPORT MEANS FOR SAID STRUCTURE, MEANS DEFINING A PIVOT FOR MOUNTING SAID STRUCTURE UPON SAID SUPPORT MEANS WITH ITS CENTER OF GRAVITY TO ONE SIDE OF SAID SUPPORT MEANS AND PROVIDING FOR PIVOTAL MOVEMENT OF ITS CENTER OF GRAVITY WITHIN PREDETERMINED FIXED LIMITS TO SAID ONE SIDE OF SAID SUPPORT MEANS, MOTOR MEANS FOR EFFECTING SUCH PIVOTAL MOVEMENTS, A HYDRAULIC CYLINDER, MEANS PIVOTALLY LINKING SAID CYLINDER TO SAID SUPPORT MEANS, A PISTON MOVABLE WITHIN SAID HYDRAULIC CYLINDER AND INCLUDING ROD MEANS EXTENDING FROM AN END THEREOF, MEANS PIVOTALLY LINKING SAID ROD MEANS TO A REGION OF SAID MASSIVE STRUCTURE DISPOSED TO THE SIDE OF SAID PIVOT FOR MOUNTING SAID STRUCTURE OPPOSITE ITS CENTER OF GRAVITY, SAID PISTON AND CYLINDER THEREBY BEING PIVOTABLE AS A UNIT RELATIVE TO SAID SUPPORT MEANS AND SAID MASSIVE STRUCTURE AS IT IS MOVED ABOUT ITS PIVOT, CONDUIT MEANS CONNECTED TO SAID CYLINDER TOWARD THE END