Varying force counterweight system

FEDERALLY SPONSORED RESEARCH

[0002] Not Applicable

SEQUENCE LISTING OR PROGRAM

[0003] Not Applicable

BACKGROUND—FIELD OF INVENTION

[0004] This invention relates generally to counterweight systems, specifically to said counterweight system that provides typically varying magnitude of force counterbalance when coupled to mechanisms having a typically varying magnitude of force to counterbalance, such as a scissors lift (or similar) apparatus.

BACKGROUND—DESCRIPTION OF PRIOR ART

[0005] With the invention of heavy movable structures such as movable bridges, counterweight systems were also invented to assist in safely and efficiently managing their heavy loads. Different types of counterweight systems were invented, depending on the configuration and counterbalance needs of a structure.

[0006] Counterweight Systems for Vertical Lift Bridges in Prior Art

[0007] Movable lift bridges, which have high vertical lift movements (50 feet or more), have utilized pulley counterweight systems to effectively and safely handle their heavy loads. A pulley is a simple machine that can be used alone to change the direction of a force. For the long vertical movements of high lift movable bridges, counterweights suspended by cables passing over pulleys (sheaves) supported at the top of lifting towers is a practical counterbalance design. The following patents by L. H. Shoemaker (U.S. Pat. No. 2,482,562) and T. Sakamoto (U.S. Pat. No. 2,040,445) are examples of movable lift bridges with pulley counterweight systems in the prior art.

[0008] Counterweight Systems for Bascular Bridges in Prior Art

[0009] For a movable bascular type cantilever bridge, the bridge deck is moved to create the draw by rotating the structure vertically (usually 70 to 80 degrees from horizontal) to open sufficiently for boats to pass and then to close again. For the bascular bridge a counterweight system is utilized to facilitate the lifting of the heavy deck structure. On a modern bascular bridge the counterweight system is a first class (seesaw like) lever, with a long arm (the bascular deck) and a short arm (the counterweight), which counterbalance each other when rotated vertically. The nature of the movement (vertical rotation) of bascule bridges is such that counterbalance can be difficult to achieve. A modern bascule bridge is considered well balanced when its counterbalance ensures safe bridge operation and machinery performance. The following patents by Lucian I. Nedelcu (U.S. Pat. No. 4,751,758) and Ivan Dvorak, Shankar Nair and Vinod C. Patel (U.S. Pat. No. 5,454,127) are examples in the prior art of bascular bridges designed with first class lever counterweight systems as described above.

[0010] Early bascule bridge decks were like a door placed horizontal with a hinge point and no cantilever short arm counterweight. They were lifted by means of ropes attached to the sides toward the extended end of the bascule cantilever deck. Counterbalancing an early design bascule deck was difficult since as the deck was lifted its counterweight requirements lessened. In 1816 M. Belidor was evidently the first to compensate for the changing counterbalance requirements of the lifting bascule deck by means of rolling a circular counterweight on a variable slope.

[0011] In the early 1800's Captain Derche also attempted to improve counterbalance performance for bascular bridges by means of a pulley counterweight system with a radius of the spiral pulley for compensating the changing bascular deck load. As the bascular deck was raised the radius of the spiral decreased in diameter to compensate for the decreasing load of the deck. The following patents in late 1800's and early 1900's by Thomas E. Brown (U.S. Pat. Nos. 590,787 and 1,151,657) and Thomas E. Brown, Jr. (U.S. Pat. No. 1,254,773) were basically modified pulley type counterweight systems to improve counterbalance during a bascular bridge deck's vertical rotational movement, when the lifting points are toward the extended end. These methods of counterbalancing a modern bascular bridge were abandoned in favor of lifting the deck at its hinge and to counterweight by means of a first class (seesaw like) lever as discussed above.

[0012] Counterweight Systems for Swing Bridges in Prior Art

[0013] For the movable swing type cantilever bridge, the draw (opening) is created by rotating the bridge deck horizontally approximately 90 degrees to open sufficiently for marine (or other) traffic to pass and then to reverse the direction of the rotation to close the draw. The typical swing bridge superstructure is supported at its center on a turntable creating a two-armed cantilever bridge deck balanced on said turntable. Therefore, the swing type cantilever bridge uses a first class (seesaw like) lever, with a counterbalanced long arm and a short arm or two equal length arms of approximately equal weight that rotates horizontally. The patent to J. B. Strauss (U.S. Pat. No. 1,158,084) is an example of a horizontal swing bridge with a first class lever counterweight system, that rotates horizontally, in the prior art.

[0014] Scissors Lift Apparatus in Prior Art

[0015] Scissors lift apparatus can be found in the prior art. Methods of improving the mechanical advantage of the scissor lift have been the main improvements in their designs. Scissor lift or similar apparatus have not been found in the prior art aided by counterweight systems. Utility patents by Michael Schirmer (U.S. Pat. No. 6,257,372 B1), Richard T. Rowan (U.S. Pat. No. 5,722,513) or Haakon G. Egeland (U.S. Pat. No. 3,628,771) are examples of scissors lift apparatus in the prior art.

[0016] To assist the motors with the large force required at the high angle (greater than 45 degrees from vertical) range of its operating cycle, the patent to Duane R. Franklin and Archibald D. Evans (U.S. Pat. No. 4,558,648) provides a scissors lift apparatus with a sealed gas cylinder as an energy storing device. The sealed gas cylinder mechanism provides force to assist the lifting of a scissors lift apparatus from its high angle positions; it is not a counterweight system since it does not provide stability in the form of neutral equilibrium or counterbalance (definitions follow) for the mechanism when stopped at any point along its full range of movement.

[0017] In mechanics energy is the capacity to do work. Work is the transfer of energy. Force is considered as a push or a pull exerted on one body by another. Potential energy from gravity (weight) is a measure of the amount of work a force will do when said weight moves vertically between two set points. Potential energy is also the movement of a spring (elastic) and is a measurement of the amount of work a force will do when said spring moves between two set points.

[0018] Stability is the resistance to any sudden change. Balance is a state in which two opposing forces are of equal strength or importance so that they effectively cancel each other out and stability is maintained. Equilibrium is the state in which all forces or processes are in balance and there is no resultant change. A counterweight is a weight that balances another weight. To counterbalance is to have an equal and opposing force or effect on something or to make something balance by putting equal weight on the opposite side. A structure in neutral equilibrium when displaced a small distance will remain stable. A counterbalanced structure can also be said to be in a state of neutral equilibrium since, when free to move, said counterbalanced structure tends to stay in its current position for all normal operating positions.

[0019] A counterweighted system is continuously counterbalanced (in a state of neutral equilibrium) when it and the structure it is coupled to tends to stay in its current position for all standard operating positions. For a counterweight system, neutral equilibrium is achieved when the current force from the counterweight is substantially the same as the current force from the object being counterweighted. Restated, to achieve a continuous state of neutral equilibrium in a counterweighted system, the balancing forces in the system remains an approximately constant equal but opposite for all standard operating positions. For example in a mechanism with a pulley type counterweight system, counterbalance is achieved by keeping the approximately constant weight in the system substantially equal but opposite by means of a tension cable over a pulley for all standard operating elevations. Ability to provide continuous counterbalance or neutral equilibrium between itself and another apparatus is what defines a counterweight system to be a counterweight system.

[0020] With the invention of the lift-slide drawbridge (patent application publication by Rex J. King, Jr. (Pub. No.: US 2003/0221266 A1)(Pub. Date: Dec. 4, 2003)), in which the deck is only lifted a few feet by means of a scissors lift or similar mechanism, a counterweight system is still desirable to safely manage the heavy loads and make possible the sizing of smaller motors for the system with a resultant overall cost savings. Since the lift-slide drawbridge's deck is only lifted a few feet, the use of a pulley type counterweight system of cables passing over sheaves supported at the top of lifting towers, with the lifting points of the counterweight system on the deck structure, becomes awkward and is not a practical or efficient counterweight system.

[0021] The need to invent a simplified counterweight system to directly resist the typically varying magnitude of horizontal force from a scissors lift apparatus became apparent when utilizing said scissors lift apparatus to actuate the heavy deck loads of a lift-slide drawbridge design. The search for a simple means of counterbalance for a scissors lift or similar apparatus led to the novel and unobvious present invention. A counterweight system, which when coupled to an apparatus with a typically varying magnitude of force provides substantially equal but opposite typically varying magnitude of force for counterbalance. Until the present invention a simple and reliable counterweight function for an apparatus with typically varying magnitude of force such as a scissors lift apparatus (as described above) did not exist.

[0022] A patent search found no prior art of a varying force counterweight system for counterbalancing a typically varying magnitude of force in mechanisms such as a scissors lift or similar apparatus.

[0023] Summary of Prior Art

[0024] After considering first class (seesaw like) lever counterweight systems utilized on bascule or swing drawbridge structures as disclosed in the prior art and as discussed and cited above, it becomes apparent that they are not an alternative in counterbalancing a loaded scissors lift (or similar) apparatus.

[0025] After considering the pulley type counterweight systems utilized on high lift drawbridge structures as disclosed in the prior art and as discussed and cited above, it becomes apparent that they are not an efficient or economically effective solution to counterbalancing a loaded scissors lift (or similar) apparatus in which the vertical movement is only a few feet.

[0026] Accordingly, the present invention of a varying force counterweight system provides a novel and unobvious yet simple and reliable counterweight function for a typically varying magnitude of force, previously unavailable, for scissors lift (or similar) apparatus. The novelty of providing a typically varying magnitude of counterbalance force to achieve continuous counterbalance with a typically varying magnitude of force from a scissors lift (or similar) apparatus, until the present invention, did not exist.

[0027] Therefore, the present invention provides novel and unique typically varying magnitude of force counterweight function to mechanisms having a typically varying magnitude of force, such as a scissors lift or similar apparatus.

OBJECTS AND SUMMARY OF THE INVENTION

[0028] The invention herein described when coupled to a scissors lift or similar apparatus effectively provides previously unknown typically varying magnitude of force counterweight function for mechanisms having a typically varying magnitude of force such as scissors lift or similar apparatus. The application of a varying force counterweight system coupled with a scissors lift or similar apparatus provides a simple means to continuously counterbalance the typically varying magnitude of force encountered when counterbalancing or lifting even very heavy structures. For example, when coupled with a scissors lift to provide counterbalance and assist in actuating the deck of a lift-slide drawbridge, the varying force counterweight system has several advantages.

[0029] The varying force counterweight system:

[0030] (a) provides neutral equilibrium (continuous counterbalance) for all standard operating positions;

[0031] (b) makes practical the employing of a scissors lift (or similar) apparatus for the lifting of very heavy loads;

[0032] (c) has neutral equilibrium (continuous counterbalance) resulting in minimum external power requirements to actuate the mechanism;

[0033] (d) provides substantially level power requirements throughout the operating cycle;

[0034] (e) can be configured in a multitude of ways to effectively meet the counterweight needs of a project;

[0035] (f) due to unique moment arm configuration, the counterweight substantially is lighter than load being counterbalanced;

[0036] (g) is a simple design with few parts making it easy to install and maintain;

[0037] (h) is expected to shorten project construction time due to simple design; and

[0038] (i) is anticipated to be lower overall in cost of design, materials and construction.

[0039] The present invention is a counterweight system which provides a unique previously unavailable typically varying magnitude of force counterweight function when coupled to a scissors lift or similar apparatus by providing a configuration of a rigid body with one degree of freedom with the main components consisting of (1) a means of support structure or frame, (2) a hinged moment arm, (3) a counterweight, (4) a sliding support arm, and (5) an means of apparatus with a typically varying magnitude of force to be counterbalanced. A moment arm is the perpendicular distance from an axis point (hinge) to the line of action of a force.

[0040] An apparatus or mechanism with a typically varying magnitude of force is an apparatus in which, typically by means of the mechanical advantage of a simple machine such as a lever, the input force required to resist an output force varies in magnitude. When actuated (moving), depending on the current configuration, the input force may vary from less than or equal to, to greater than the output force or vice versa as it moves from one end to the other end of its normal range of operation. When static (not moving) the magnitude of the input force will be substantially constant at a given constant output force. The scissors lift apparatus as proposed in the preferred embodiment of this invention is a instance if a typically varying magnitude of force which varies from less than or equal to, to greater than the output or vice versa as it moves from one end to the other end of its normal range of motion.

[0041] Specifically, in accordance with a the preferred embodiment of this invention, a counterweight apparatus when coupled to an apparatus to be counterweighted becomes an interconnected rigid body with one degree of freedom that remains continuously interconnected when in service. A rigid body mechanism is a combination of connected parts in which all parts remain at fixed distances from one another. A rigid body mechanism with one degree of freedom requires only one coordinate to describe the approximate position of one part to be known to determine the approximate location of each part on the rigid body. The present invention's interconnected rigid body with one degree of freedom when configured to specification and with appropriate counterweight achieves a state of neutral equilibrium (continuous counterbalance) which means said structure when static (not moving) tends to stay in its current position for all normal operating positions.

[0042] While in motion the present invention also provides work (the potential energy from the vertical displacement of the counterweight) which assists in balancing the frictional and actuating forces inherent during said motion resulting in a substantially sustained reduction in power requirements that are also substantially consistent in magnitude (level).

[0043] A unique and unobvious feature of the present invention is a means to assure a continuous compressive force connection between the counterweight side and the load side of the interconnected rigid body mechanism. This unique and unobvious feature requires both sides of the apparatus to be continuously dependent on a common sliding support arm for their stability (a common compression connection). In other words, the varying force counterweight system (counterweight side) would be unstable and collapse (suddenly move to successive positions of less potential energy until stable) without its common coupled connection with a scissors lift or similar means of apparatus to be counterweighted (load side) and vice versa. This interdependency, one side leaning on the other, creates the ability for the system to have the required continuous compression force on a common sliding support arm. This leaning on each other is further assisted by the scissors lift apparatus and the sliding support arm's slidably engaged connection with the means of support structure resisting vertical movement. The resisting of vertical movement effectively cancels the vertical component of the force from the varying force counterweight system and the scissors lift apparatus. The remaining horizontal component of force from the varying force counterweight system and the scissors lift apparatus are opposite and opposing and available to form a required common compression connection.

[0044] The required continuous counterweight side of the apparatus pushing (compression force) on the load side of the apparatus and vice versa is a unique feature to the present counterweight invention. For example, the opposite is what occurs in a pulley type counterweight system where the counterweights pull away (tension force) from each other with an equal but opposite tension force by means of a common interconnecting cable. The double cantilever (seesaw like) counterweight systems of the bascule and swing bridges are configured to resistance bending or rotational force.

[0045] The horizontal forces from the counterweight side and the load side of the interconnected rigid body are directed to the sliding support arm which is their common connection. Both the counterweight side and the load sides continuous opposite and opposing leaning on the sliding support arm causes a continuous compressive force on this common connection assuring it stays in compression but without another innovation it does not achieve the mandatory function of continuous counterbalance at any point along its range of operation when stationary and actuated.

[0046] A second unique and unobvious feature of the present invention is also required to assure continuous counterbalance throughout its standard range of operation. This feature provides the ability for the typically varying magnitude of the force from the counterweight side to counterbalance the typically varying magnitude of the force from the load side of the interconnected rigid body mechanism. By being able to continuously counterbalance the varying magnitude of the force from the load side, the forces in the interconnected rigid body mechanism effectively cancel each other where continuous counterbalance in the interconnected rigid body results.

[0047] A third unique and unobvious feature of the present invention is also required to assure that a continuous varying rate of potential energy is provided while in motion throughout its standard range of operation. The rate of change of vertical movement varies from maximum vertical movement when the slidably engaged contact point of the sliding support arm is at its nearest to the first end of the moment arm and decreases as it is urged away from said first end of the moment arm and vice versa. This feature provides the ability for a typically varying magnitude of the force from the counterweight side to be available while actuated (in motion), to counterbalance the typically varying magnitude of the force from the load side of the interconnected rigid body mechanism and to assist in balancing the frictional and actuating forces inherent during actuation. By being able to continuously counterweight the varying magnitude of force from the load side, the majority of the forces in the interconnected rigid body mechanism remain substantially counterbalanced during said motion resulting in a substantially sustained reduction in power requirements and substantially consistent (level) power requirements.

[0048] To explain the present inventions ability to provide a typically varying magnitude of counterweight force we must envision how a scissors lift or similar apparatus having a typically varying magnitude of force is configured. A first arm of a scissors lift and a second arm of said scissors lift apparatus are identical. The first and second arms of the scissors lift are pivotally linked to one another at their central points. The first arm's upper end is rotationally fixed to a beam and the second arm's upper end is slidably engaged to said beam. The second arm's lower end is rotationally fixed to a lower support structure and the first arm's lower end is slidably engaged to said support structure. The first arm's upper rotationally fixed end is configured to maintain a position substantially above the second arm's lower rotationally fixed end. The second arm's upper slidably engaged end is configured to maintain a position substantially above the first arm's lower slidably engaged end.

[0049] All four ends of the two arms of the scissors lift allow for rotational movement. The first arm's upper rotationally fixed end resists horizontal movement of the beam. The second arm's lower rotationally fixed end resists horizontal movement of the scissors lift apparatus. The beam coupled to the upper ends of the first and second arms of the scissors lift apparatus is now configured to be actuated up and down relative to the support structure by means of applying a horizontal actuating force (R) to said first arm's lower slidably engaged end.

[0050] Therefore, given the above configuration, if full range of movement of a scissors lift apparatus is from 20°≦θ≦57° from the vertical for all values of θ1<θ2 the corresponding values of the horizontal actuating force (R) at the first scissors lift arm's lower slidably engaged end is R1<R2 consistently throughout the defined full range of movement of said scissors lift apparatus. This means that the lower the scissors lift apparatus is (the greater the angle from vertical) the larger the required counterbalance force to resist the horizontal actuating force (R) and provide neutral equilibrium to the said scissors lift apparatus. Restated, to counterbalance a scissors lift apparatus with the above configuration the opposite and opposing counterweight force will need to simultaneously increase or decrease as the horizontal actuating force (R) from said scissors lift apparatus increases or decreases.

[0051] In accordance with another preferred aspect of this invention, the counterweight apparatus comprises a means of support structure with a first end of a moment arm hinged to said means of support structure. A counterweight is attached to the second end of said moment arm. A sliding support arm is slidably engaged with said moment arm. The sliding support arm is structured to be simultaneously slidably engaged to and support the moment arm, slidably engaged with the support structure and pivotally linked to the scissors lift apparatus. The varying force counterweight system's sliding support arm is pivotally linked to the scissors lift apparatus at the scissors lift's lower slidably engaged end. The sliding support arm is slidably engaged with the means of support structure to provide for stability, therefore, as needed, guides and flanged wheel trucks are provided along the sliding support arm. The result of the sliding support arm's slidably engaged connection with the means of support structure is that the vertical movement of said sliding support arm is resisted. The resisting of the vertical movement effectively cancels the vertical component of the force from the varying force counterweight system. The remaining horizontal component of force remains to resist the opposite and opposing horizontal force from the scissors lift apparatus.

[0052] The moment arm is configured to be slidably supported by the sliding support arm along a predetermined line of contact between the first and second ends of said moment arm. A drive means for bidirectional (back and fourth) actuating of the sliding support arm is coupled to said sliding support arm or another convenient location. Bidirectional actuation increases or decreases the magnitude of available counterbalance force to the scissors lift apparatus. The typically varying magnitude of force is due to the lowering or rising of the center of gravity (at a varying rate) with the decreasing or increasing the respective relative distances between the slidably engaged contact point of the sliding support arm with the first and second ends of the moment arm during bidirectional actuation. When the movement of the slidably engaged contact point of the sliding support arm is toward the direction of the second end of the moment arm (counterweight end), the scissors lift apparatus rises and the counterweight lowers, at a varying rate, resulting in a decreasing of the magnitude of the force from the counterweight to the sliding support arm which substantially matches the decreasing magnitude of force from the rising said scissors lift apparatus. When the movement of the slidably engaged contact point of the sliding support arm is toward the direction of the first end of the moment arm (hinged end), the scissors lift apparatus lowers and the counterweight rises, at a varying rate, resulting in an increasing of the magnitude of the force from the counterweight to the sliding support arm which substantially matches the increasing magnitude of force from the lowering said scissors lift apparatus.

[0053] The unique combination of varying rate of counterweight vertical movement and changes in the relative location of the sliding support arm's contact point with the moment arm provides the typically varying magnitude of counterweight force to counterbalance the typically varying magnitude of force from a scissors lift apparatus. As a result the varying force counterweight system achieves the required continuous counterbalance (neutral equilibrium) in the interconnected rigid body of the present invention.

[0054] The basic nature of the present invention is the application of a combination of mechanical principles not previously understood capable of being combined for the purpose of counterbalancing mechanisms. Depending on the mechanism being counterbalanced, the counterweight system of present invention may require reconfiguring. It can therefore be appreciated the final configuration of a varying force counterweight system coupled with an apparatus to be counterweighted will vary depending on the nature of said apparatus to be counterweighted. For example, in some applications the source of the potential energy from the counterweight (potential energy from gravity) may be replaced with a spring (elastic potential energy).

[0055] The means of apparatus to be counterweighted may comprise any means of apparatus which requires a varying magnitude of counterbalance force to be continuously counterbalanced, such as the scissors lifts preceded in utility patents by Michael Schirmer (U.S. Pat. No. 6,257,372 B1), Richard T. Rowan (U.S. Pat. No. 5,722,513) or Haakon G. Egeland (U.S. Pat. No. 3,628,771).

[0056] The means of actuation of a varying force counterweight system coupled with a scissors lift or similar apparatus may comprise any means of actuation which is capable of actuating the mechanism such as a hydraulic ram.

[0057] Preferably the means of sliding includes guides and flanged wheel trucks. The means of sliding may comprise of any mechanism capable of providing the needed sliding (or straight line motion).

[0058] The means of pivotal link of the present invention with a scissors lift or similar apparatus may comprise any means of pivotal link which provides for the required connection movements and may be placed in a state of continuous compression for the full range of operation of the present invention.

[0059] In accordance with an alternate embodiment of this invention, a moment arm is adjustable in length. On movable bridge structures the deck load on the scissors lift apparatus is almost constant and adjustment in the varying force counterweight system is seldom needed. Adjustment in the varying force counterweight system for movable bridge structures can easily be made by adding or removing a portion of the counterweight.

[0060] In some applications of the varying force counterweight system the load on the scissors lift apparatus will be different with each lift. As the load on the scissors lift apparatus changes, the counterweight on the varying force counterweight system must also be adjusted. By adjusting the length of the moment arm the magnitude of force from the counterweight available for counterbalance of the scissors lift apparatus can also adjusted.

[0061] In accordance with another alternate embodiment of this invention, the initial distance between the pivot axis of the moment arm and the initial contact point of the moment arm can be adjusted to tune the system to perform according to a required specification. Therefore, the initial distance between the pivot axis of the moment arm and the initial contact point of the moment arm is adjustable.

[0062] In accordance with another alternate embodiment of this invention, an interconnected rigid body with one degree of freedom apparatus with a varying force counterweight system is transportable. For some applications such as movable bridge structures, the relocation of the varying force counterweight system is seldom needed. Any required adjustment in the position of the interconnected rigid body with one degree of freedom apparatus with a varying force counterweight system can easily be made by designing minor adjustment into the support structure.

[0063] In other applications, an interconnected rigid body with one degree of freedom apparatus with a varying force counterweight system will need to be relocated continuously. For these applications the interconnected rigid body with one degree of freedom apparatus support structure can be designed into a skid, with wheels or rollers, or slidably engaged or fixed to a secondary means of transport.

[0064] In accordance with another alternate embodiment of this invention, varying force counterweight systems are placed in series and/or in parallel to one another. For some applications such as movable bridge structures, space or other limitations or special varying force requirements may require the linking a plurality of varying force counterweight systems in series and/or in parallel with one another to obtain a desired varying magnitude of counterweight force function.

[0065] While the preferred embodiments of the invention have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

SUMMARY

[0066] In accordance with the present invention, a varying force counterweight system is a counterweight system which provides previously unavailable typically varying of force counterweight function when coupled to a scissors lift or similar apparatus by providing a configuration of a rigid body with one degree of freedom with the main components consisting of (1) a means of support structure or frame, (2) a hinged moment arm, (3) a counterweight, (4) a sliding support arm, and (5) an apparatus with a typically varying magnitude of force to be counterbalanced. When properly configured a varying force counterweight system has at least three novel and unobvious features to ensure counterweight function when coupled to an apparatus with a typically varying force to be counterbalanced.

[0067] The first novel and unobvious feature is the means to assure the common connection between the counterweight and the load side of the interconnected rigid body mechanism of the present invention is always in compression (force). By providing a common sliding support arm which the opposite and opposing forces from both sides of the mechanism rely on for stability, the required compression connection is always present.

[0068] The second novel and unobvious feature of the present invention assures continuous counterbalance (neutral equilibrium) in the interconnected rigid body of the mechanism by means of the present inventions unique counterweight and hinged moment arm's continuous reconfiguration during movement which provides instantaneous changes in the magnitude of the force delivered by the counterweight system.

[0069] The third novel and unobvious feature of the present invention assures continuous varying rate of potential energy is provided to the interconnected rigid body mechanism while in motion. Restated, when actuated the present inventions unique counterweight and hinged moment arm configuration also moves vertically at a varying rate providing potential energy at a varying magnitude of force to assist the means of actuation. This feature provides assistance in balancing the frictional and actuating forces inherent during actuation resulting in a sustained reduction in power requirements and substantially consistent (level) power requirements.

[0070] Working together the novel features of the present invention assure counterbalance (neutral equilibrium) will occur, making it a unique and useful counterweight system when coupled to an apparatus with a typically varying magnitude of force to be counterbalanced.

DRAWINGS

[0071] Drawing Figures

[0072]
FIG. 1 illustrates an elevation view of a preferred embodiment of the invention showing the varying force counterweight system pivotally linked to a scissors lift apparatus with said scissors lift apparatus in the lowered position.

[0073]
FIG. 2 illustrates an elevation view of a preferred embodiment of the invention showing the varying force counterweight system pivotally linked to a scissors lift apparatus with said scissors lift apparatus in the raised position.

PREFERRED EMBODIMENTS OF THE INVENTION

[0074] The operation of the varying force counterweight system 1 consists of a bidirectional (back and forth) sliding movement; when activated (in motion) to the left the sliding support arm 3 simultaneously lifts the scissors lift apparatus 2 and said sliding support arm's 3 slidably engaged contact point 9 with the moment arm 5 moves left providing a simultaneous decreasing of the magnitude of the counterbalancing force. To lower the scissors lift apparatus 2 the process is reversed. When stationary (not moving) the varying force counterweight system 1 provides substantially constant neutral equilibrium (continuous counterbalance) function.

[0075] FIGS. 1-2—Preferred Embodiment

[0076] The preferred embodiment of the present invention is illustrated in FIGS. 1-2 elevation views. A support structure 4 is provided such that when a varying force counterweight system 1 and a scissors lift apparatus 2 or similar apparatus are coupled to said support structure 4 and interconnected to each other they become an interconnected rigid body with one degree of freedom apparatus 21 that remains continuously interconnected by means of a sliding support arm 3 while in service.

[0077] A means of support structure 4 may be a frame, a foundation or any structure capable of providing the support necessary for the apparatus to become an interconnected rigid body with one degree of freedom 21.

[0078] A moment arm 1 with said moment arm's first end 7 hinged to a support structure 4. A counterweight 6 is attached to the second end of said moment arm 8. A sliding support arm 3 is slidably engaged with and supporting the moment arm 5. The sliding support arm 3 is structured to be simultaneously slidably engaged with the moment arm 5 between the first 7 and second 8 ends of said moment arm 5; slidably engaged with the support structure 4 with a sliding support 10; and pivotally linked to the scissors lift apparatus 2 at the lower scissors lift arm's slidably engaged end 19.

[0079] The result of the sliding support arm's 3 slidably engaged connection or sliding support 10 with the means of support structure 4 is that the vertical movement of said sliding support arm 3 is resisted. The resisting of the vertical movement effectively cancels the vertical component of the force from the varying force counterweight system 1. The remaining horizontal component of force is directed to resist the horizontal force from the scissors lift apparatus 2.

[0080] The sliding support arm 3 is slidably engaged with said means of support structure 4 to provide for stability, therefore as and where needed a means of guides and flanged wheel trucks 15 are coupled to the sliding support arm 3.

[0081] When a varying force counterweight system 1 is coupled to a scissors lift apparatus 2 by means of a sliding support arm 3, said sliding support arm 3 is configured to cancel the opposite and opposing horizontal component of the their respective forces sufficiently to cause a counterbalancing of the loads of the overall mechanical system. The operation of the varying force counterweight system 1 consists of a bidirectional movement of a sliding support arm 3 between the varying force counterweight system 1 and the scissors lift apparatus 2. When the movement of the sliding support arm 3 is in the direction of the scissors lift apparatus 2, said scissors lift apparatus 2 is raised as shown in FIG. 2 and when the movement of the sliding support arm 3 is in the direction of the varying force counterweight system 1 said scissors lift apparatus 2 is lowered as shown in FIG. 1.

[0082] The moment arm 5 is configured to be slidably engaged and supported by the sliding support arm 3 between an initial contact point 11 and a final contact point 12 which are located between the first 7 and second ends 8 of said moment arm 5. The rightmost point of operation is when the scissors lift table 14 is at its lowest point and the sliding support arm 3 is slidably engaging the moment arm 5 at the initial contact point 11. The leftmost point of operation is when the scissors lift table 14 is at its highest point and the sliding support arm 3 is slidably engaging the moment arm 5 at the final contact point 12.

[0083] At the rightmost point of operation the elevation of the counterweight 6 and the distance from the center of gravities of said counterweight 6 and the moment arm 5 to the initial contact point 11 where said moment arm 5 is being slidably engaged is maximum. In this configuration the maximum magnitude of force from the varying force counterweight system 1 is obtained.

[0084] At the leftmost point of operation the elevation of the counterweight 6 and the distance from the center of gravities of said counterweight 6 and the moment arm 5 to the final contact point 12 where said moment arm 5 is being slidably engaged is minimum. In this configuration the minimum magnitude of force from the varying force counterweight system 1 is obtained.

[0085] The rate of change of vertical movement varies from maximum vertical movement when the slidably engaged contact point 9 is at its nearest to the initial contact point 11 decreasing as it is urged away toward the final contact point 12 and vice versa.

[0086] In a general explanation, when actuated the current slidably engaged contact point 9 of the sliding support arm 3 with the moment arm 5 moves from right to left as its relative spatial relationship with the first 7 and second ends 8 of the moment arm 5 and the counterweight 6 continuously change and the magnitude of force from the varying force counterweight system 1 decreases. The centers of gravity also move downward at a varying rate providing a varying magnitude of potential energy to the system. The decrease in the magnitude of the force is due to the simultaneous results of the leftward movement. The opposite occurs when the current slidably engaged contact point 9 of the sliding support arm 3 moves from left to right. The means of actuation can be hydraulic rams H coupled to the sliding support arm 3 or another well-situated point of actuation.

[0087] A scale model of an interconnected rigid body with one degree of freedom apparatus 21 consisting of a scissors lift apparatus 2 and a varying force counterweight system 1 was built and initial tests using it are consistent with the previous explanation of the mechanics. The scale model was constructed with a 38 lb. moment arm 5 with a center of gravity located approximately four (4) feet from the pivot axis of said moment arm 13. A series of tests were conducted with approximately 150 lbs. of load L (weight) on the scissors lift apparatus 2 (including self-weight). The angle of moment arm 5 varied from 16.5°≦α≦8.5° from horizontal.

[0088] In the first test, the varying force counterweight system 1 was uncoupled from the scissors lift apparatus 2 and the horizontal reaction R required to lift said scissors lift apparatus 2 over the full range of movement of said scissors lift apparatus 2 (54°≦θ≦25°) from vertical was observed. The maximum horizontal reaction R required to lift the scissors lift apparatus 2 over its full range of movement was greater than 150 lbs.

[0089] In the second test, the varying force counterweight system 1 was coupled to the scissors lift apparatus 2 with the 38 lb. moment arm 5 slidably engaged with the sliding support arm 3. With no additional counterweight 6 added to the varying force counterweight system 1, the maximum additional horizontal force R required to lift the scissors lift apparatus 2 over its full range of movement was reduced to 140 lbs. The interconnected rigid body with one degree of freedom apparatus 21 was not operating in neutral equilibrium (not counterbalanced).

[0090] In the third test a 37 lb. counterweight 6 was placed on the moment arm resulting in a combined total counterweight 6 of approximately 75 lbs. with a center of gravity located approximately 5.8 feet from the moment arm's 5 pivot axis of the moment arm 13. The maximum additional horizontal force R required to lift the scissors lift apparatus 2 over its full range of movement was 30 lbs. and the interconnected rigid body with one degree of freedom apparatus 21 was operating in neutral equilibrium (continuous counterbalance).

[0091] When operating in neutral equilibrium in the third test, the interconnected rigid body with one degree of freedom apparatus 21 provided an 80% reduction in energy requirement compared with the scissors lift apparatus 2 uncoupled from the varying force counterweight system 1. If similar results are obtained on a large scale scissors lift apparatus 2 with a total load weighting 300 tons the power required to lift the scissors lift apparatus 2 approximately 3.5 feet in 30 seconds would be approximately 29 horsepower.

[0092] In another series of tests, it was observed that the magnitude of the force required to lift the scissors lift apparatus 2 dropped in proportion to the counterweight 6 added to the moment arm 5. Counterweight 6 was incrementally added to the moment arm 5 until the interconnected rigid body with one degree of freedom apparatus 21 began operating in neutral equilibrium. More weight was incrementally added to the counterweight 6 and the interconnected rigid body with one degree of freedom apparatus 21 continued to operate in neutral equilibrium (continuous counterbalance) until the horizontal force R to lift the scissors lift apparatus 2 was reduced to zero (0) and the scissors lift apparatus 2 tended to lift on its own. These observations demonstrate that the interconnected rigid body with one degree of freedom apparatus 21 operates in neutral equilibrium over a large variation in the weight of the counterweight 6, given a fixed load on the scissors lift apparatus 2, revealing the present invention to be a very stable and easy to operate counterweight system.

Reference Numerals in Drawings

[0093]

1
varying force counterweight system

[0094]

2
scissors lift apparatus

[0095]

3
sliding support arm

[0096]

4
means of support structure

[0097]

5
moment arm

[0098]

6
counterweight

[0099]

7
first end of the moment arm

[0100]

8
second end of the moment arm

[0101]

9
slidable engaged contact point

[0102]

10
sliding support

[0103]

11
initial sliding contact point

[0104]

12
final sliding contact point

[0105]

13
pivot axis of moment arm

[0106]

14
scissors lift table

[0107]

15
flanged wheel trucks

[0108]

16
scissors lift first arm

[0109]

17
scissors lift second arm

[0110]

18
scissors lift arm's rotationally fixed end

[0111]

19
scissors lift arm's slidably engaged end

[0112]

21
interconnected rigid body with one degree of freedom apparatus

[0113] L load

[0114] H hydraulic cylinder

[0115] R horizontal force

[0116] θ scissors lift arm's angle from vertical

[0117] α moment arm angle from horizontal

[0118] FIGS. 1-2—Alternative Embodiments

[0119] In accordance with an alternate embodiment of this invention, the varying force counterweight system 1, the load L on the scissors lift apparatus 2 will be different with each lift. As the load L on the scissors lift apparatus 2 changes, the counterweight 6 on the varying force counterweight system 1 must also be adjusted. By adjusting the length of the moment arm 5 the magnitude of force from the counterweight 6 available for counterbalance of the scissors lift apparatus 2 can also be adjusted.

[0120] The means of adjusting the length of the moment arm 5 may comprise any means which permits the shortening or lengthening of said moment arm 5.

[0121] In accordance with another alternate embodiment of this invention, the initial distance between the pivot axis of the moment arm 13 and the initial contact point 11 of the moment arm 5 can be adjusted to tune the system to perform according to a required specification. Therefore, the initial distance between the pivot axis of the moment arm 13 and the initial contact point 11 of the moment arm 5 is adjustable.

[0122] The means of adjusting the initial distance the pivot axis of moment arm 13 and the initial contact point 11 of the moment arm 5 may comprise any means which permits the adjustment of the components.

[0123] In accordance with another alternate embodiment of this invention, an interconnected rigid body with one degree of freedom apparatus 21 with a varying force counterweight system 1 is transportable. For some applications such as movable bridge structures, the relocation of the varying force counterweight system is seldom needed. Any required adjustment in the position of the interconnected rigid body with one degree of freedom apparatus 21 with a varying force counterweight system 1 can easily be made by designing minor adjustment into the support structure.

[0124] In other applications, an interconnected rigid body with one degree of freedom apparatus 21 with a varying force counterweight system 1 will need to be relocated continuously. For these applications the interconnected rigid body with one degree of freedom apparatus 21 support structure 4 can be designed into a skid, with wheels or rollers, or slidably engaged or fixed to a secondary means of transport.

[0125] The means of transport of a an interconnected rigid body with one degree of freedom apparatus 21 with a varying force counterweight system 1 may comprise any means of transport which permits the relocation of the mechanism from one location to another.

[0126] In accordance with another alternate embodiment of this invention, varying force counterweight systems 1 are placed in series and/or in parallel to one another. For some applications such as movable bridge structures, space or other limitations or special varying force requirements may require the linking a plurality of varying force counterweight systems 1 in series and/or in parallel with one another to obtain a desired varying magnitude of counterweight force function.

[0127] The means of linking a plurality of varying force counterweight systems 1 in series and/or in parallel with one another to obtain a desired varying magnitude of counterweight force function may comprise any means of linking which obtain the required counterweight function.

[0128] While the preferred embodiments of the invention have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

[0129] Conclusion, Ramifications, and Scope

[0130] The need to invent a simplified counterweight system to directly resist the typically varying magnitude of horizontal force R from a scissors lift apparatus 2 became apparent when utilizing said scissors lift apparatus 2 to actuate the heavy deck loads of a lift-slide drawbridge design. The search for a simple means of counterbalance for a scissors lift 2 or similar apparatus led to the novel and unobvious present invention. A counterweight system, which when coupled to an apparatus with a typically varying magnitude of force provides equal but opposite typically varying magnitude of force for counterbalance. Until the present invention, counterweight function for an apparatus with typically varying magnitude of force such as a scissors lift apparatus 2 did not exist.

[0131] Although the description above contains much specificity, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Depending on the configuration and the typical varying magnitude of the force of a mechanism the varying force counterweight system 1 is coupled to, variations in the design will be required. For example, it may be of benefit to use a spring to supply potential energy for counterbalance rather than the weight of counterweight 6, etc.

[0132] Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.

Varying force counterweight system

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