Elevator – industrial lift truck – or stationary lift for vehicle – Having fluid dampening means regulating load support movement – Includes piston and cylinder attached to support by cable
Reexamination Certificate
2001-05-03
2003-12-16
Lillis, Eileen D. (Department: 3652)
Elevator, industrial lift truck, or stationary lift for vehicle
Having fluid dampening means regulating load support movement
Includes piston and cylinder attached to support by cable
C187S253000, C187S272000, C187S275000, C187S345000, C187S404000, C254S386000
Reexamination Certificate
active
06662905
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an ELEVATOR WHICH COUNTERWEIGHT IS ALSO THE PLUNGER OF THE PROPELLING FLUID DYNAMIC DEVICE WHICH PRODUCES AND CONTROLS THE MOVEMENTS THEREOF, that brings several advantages over the other vertical translation devices known so far.
More specifically, this invention relates to an elevator lifter for vertically carrying people or things, of the type having a car which moves between vertical guides, arranged within a conduit called “hoistway”, said car being supported on a cable extending to a pulley or wheel that is part of the elevator, wherefrom it projects for extending to a counterweight means which is cooperative with said elevator.
In very well known embodiments, said pulley is powered by an electrical engine which operates the cable extending between the car and the counterweight.
The usual, universally known purpose of the “counterweight” is to reduce the power of the engine. In fact, generally the counterweight has a weight that is equal to that of the car increased in about 40 to 45% of the duty load; in this way the engine only has to lift the unbalanced part of the load and avoid any rubbing.
In this particular case, the invention relates to an elevator conceived with the novel feature of using the counterweight as a piston or plunger of a fluid dynamic device that propels said vertical movements to the car.
For the rest of the constructive aspects, the inventive elevator, as regards its car and assembly (guides, parachutes, and the like), is of a conventional type. It is a rule-conforming, “standard” elevator.
Consequently, this is an embodiment that from the beginning avoids the need of installing a lifting machine that may be arranged either above or below the hoistway for commanding the movement of said wheel that drives and powers the cable. Instead, a single freely rotating pulley is disposed, the function of which is to guide the cable to the equilibrated counterweight which, as indicated by the title of the invention, is the plunger of the propelling fluid dynamic device.
PRIOR ART
Several constructive and functional embodiments of elevators are known. Among these embodiments, the most traditional one is that in which cables guided and powered from a generally electrical engine are used for the vertical movement of the car. There also exist some others that usually use vertical racks wherein the operating teeth are engaged, the teeth being powered by an engine accommodated in the car itself.
Among the elevators that use propelling fluid dynamic devices are both, hydraulic lifts and pneumatic lifts. Hydraulic lifts known at present have similar features located to that of electrical lifts. The car also moves being guided by vertical steel profiles placed in the hoistway and have the characteristic of including a cylinder inside which a piston for raising the car moves. A tight pipe extends from the cylinder bottom to the liquid reservoir; the liquid reservoir is generally placed in the machine room, where also the hydraulic pump is accommodated with its corresponding engine and directional valves. The pump pressure injects liquid in the bottom of the cylinder, so the plunger is pushed upwards, thus raising the car. When the fluid supply is interrupted, the car stops. Downward movement starts from an electrical order, which produces the opening of the valves so as to allow for the liquid to go back to the reservoir. The weight of the plunger, the car, the load and the fluid itself, generate a pressure sufficient for the liquid to outflow. As fluid pressure varies according to the load being carried, downward movement speed also varies as a function of the load.
The advantage of this type of lifters is that no large installations above the hoistway are required, so it is fully used for movements of the car.
A generalized drawback is that the length of the cylinder should be slightly longer that the car path of motion, which creates the need for large installations out of the hoistway, generally below the hoistway. It is for this reason that they have a limited distance to travel (two or three stops). They are devices that operate under great pressure, so their installations are highly expensive, not only due to their size, but also for the constructive precision of the hydraulic parts necessary for them.
In this sense, those, which use side pistons, are preferred, as their stroke is half the path of motion of the car; nevertheless the pulley systems that are used led to duplication of efforts with a lot of rubbing.
In fact, the hydraulic elevators known at present, the cylinders and pistons are rectified and require good seals or detents to support pressures higher than 5 kg/cm
2
, i.e. 5 atmospheres or higher.
Among disclosures prior to this application U.S. Pat. No. 3,318,418 to William C. Kilpatrick can be mentioned, wherein it is taught an installation for a pneumatic elevator of the type where the car vertically moves as a piston within a tube (that forms the hoistway of the lift), in response to the pneumatic pressure existing in said tube, below the car.
U.S. Pat. No. 2,927,661 to Kristek et. al. teaches a lifter for people or loads that also uses a tight closing tube wherein a car moves. Said tube is part of a very particular pneumatic circuit where air is pressure-flown so as to produce the raising of the car. French patent number 71.02437 to Saunier Duval discloses a car which is the piston of a vertical pneumatic cylinder that moves upwards, by effect of an overpressure applied below the car, while it moves downward when a depressurization inside the tube and over the car is caused.
The applicant of the present invention is also the creator of a depressurization pneumatic elevator which was the subject matter of the Argentinean patent 245673 which fits a special construction through which the car raises or moves downward as a function of the depressurizations created between the ceiling of the car and the upper part of the tube over which it moves.
There are no previous disclosures regarding the use of the counterweight itself as a propelling means for moving the car upward and downward. In all cases they are used with the purpose of balancing the load, in an attempt that the effort made by the propelling means be the lowest possible. In this regard, mention is made to EP 0 957 060 to Klitzke Dieter where a conventional hydraulic elevator having the counterweight disposed external to the propelling cylinder is disclosed.
U.S. Pat. No. 5,901,814 to Leandre Adifon et. al. teaches an hydraulic elevator having a counterweight. In this case, the car is associated to the piston of a hydraulic cylinder, which is the propelling means for upward and downward movements thereof. In this case, the counterweight acts as such. It has the function of reducing the effort of the cylinder for movements. It has the same function as the balanced counterweights used in most elevators.
U.S. Pat. No. 5,957,779 to Walter F. Larson refers to a tower with a couple of gondolas hanging therefrom which, by their free ends, are attached to the piston of a hydraulic cylinder. Single counterweights are included for each gondola hanging from the same piston as a resource for balancing the load. Counterweights are not used as a propelling resource, either.
U.S. Pat. No. 5,975,246 to Renzo Toschi teaches a hydraulically balanced elevator. The patent discloses an elevator combining the use of a first cylinder and a second cylinder which are integral with a single hydraulic circuit which regulates the balance of the load in the car. Counterweights are included on the second cylinder. Neither in this case counterweights are used as movement propelling.
U.S. Pat. No. 5,238,087 to Alfonso Garrido et. al. relates to improvements tending to achieve energy savings for hydraulic elevators. In this case an hydraulic means is disclosed, the means is attached to the counterweight means so as to bear the weight of the car plus a 50$ of the duty load. It is a counterweight associated to a hydraulic resource, but nonetheless the use of the counter
Anderson Chad C.
Chin Paul T.
Lillis Eileen D.
Shannon John P.
Venable LLP
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