Hydraulic power unit for an elevator drive

Information

  • Patent Grant
  • 6371005
  • Patent Number
    6,371,005
  • Date Filed
    Monday, August 30, 1999
    25 years ago
  • Date Issued
    Tuesday, April 16, 2002
    22 years ago
Abstract
A vertically oriented hydraulic power unit for an elevator drive includes an outer tank for drive fluid and an inner tank for fluid used to submerge and cool a motor, the fluids being exchangeable to maintain temperature in the inner tank at or below a specified maximum temperature. Oil returning from an elevator piston is fed into said inner tank to keep the inner tank sufficiently cool.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The invention relates to hydraulic elevators. More particularly, the invention relates to a pump and tank for a hydraulic power unit.




2. Prior Art




Hydraulic elevator systems are popular for lower rise applications since installation cost is generally lower than traction type elevator systems. The car of a hydraulic elevator system is displaced upwardly and downwardly within a hoistway by a piston disposed within a drive cylinder located at the base of the elevator hoistway. In order to provide pressurized fluid to the drive cylinder and, on demand, drive the piston and elevator car connected thereto upwardly, a pump and motor assembly is required. Commonly pump and motor assemblies of the prior art were maintained in a machine room wherein a large horizontally disposed tank contained the pump and motor therewithin and sufficient oil to both drive the elevator car to its highest intended stopping point and still cover the motor and pump. Such tanks are very large because of the amount of oil required to both drive the piston and keep the motor and pump submerged. A benefit of the prior art arrangement is that noise generated by the motor and pump is contained substantially to the machine room and therefore is insulated from the elevator car. Referring to

FIG. 1

, a prior art hydraulic power unit is illustrated in a schematic machine room. The device


10


is generally mounted upon a type of support


12


within room


14


. Tank


16


occupies a large portion of the machine room


14


. The motor


18


and pump


20


are illustrated as mounted within tank


16


and are completely submerged in oil


22


. It will be appreciated that the minimum oil level is indicated at


24


in the figure. The maximum oil level


26


will illustrate the difference between the oil required to maintain the pump and motor in a submerged condition and the oil required to operate the piston of the hydraulic elevator system. In many configurations more oil is actually required to submerge the motor and pump than is required to run the elevator. Because of this, very large tanks


16


are required to handle the amount of oil. Furthermore, a significant cost is incurred by the reservoiring of so much oil.




Mounted atop tank


16


is a valve block


28


which generally also includes a shut-off valve


30


. Valve block


28


is configured to supply low to medium pressure oil at about


12


to


45


bar to the cylinder


32


of the elevator system and allow oil to return to the tank


16


when the elevator car of the elevator system is lowered requiring the bleed-off of pressure from cylinder


32


and piston


34


. Since space is an expensive commodity in modem building architecture, machine roomless elevator systems are becoming more accepted and in fact demanded. Because of the size of the hydraulic power unit


10


in a conventional hydraulic elevator system, building a hydraulic elevator system without a machine room has heretofore been nearly impossible. The elevator art is thus in need of a system that allows the hydraulic elevator power unit to be mounted such that a machine room is not required.




SUMMARY OF THE INVENTION




The above-identified drawbacks of the prior art are overcome or alleviated by the hydraulic power unit of the invention.




A novel hydraulic power unit is created by vertically configuring various components of the unit and modifying internal structure of the tank thereof in order to maintain oil levels and temperatures required for motor and pump operation while avoiding the necessity of the large volumes of oil required in the prior art. The invention further provides for cooling of the oil reservoir surrounding the motor and pump. Finally the invention provides an insulated cover for the valve block assembly thus ameliorating the noise transmitted through the valve block.




In the vertical configuration made possible by the present invention, the hydraulic power unit of the invention is rendered significantly more compact than its conventional cousin enabling the fitment of the hydraulic power unit in the hoistway with the elevator car. Preferably, the unit is placed in a clearance space between a wall of the hoistway and side of the elevator car. By allowing for in-hoistway containment of the hydraulic power unit, the need for a machine room is obviated.




Since the invention locates the power unit in the hoistway and the machine room is deleted, a conventional rescue pump is inconvenient to use as it requires a technician or rescue personnel to enter the hoistway to operate the same. The invention therefore includes a rescue pump located more conveniently.











BRIEF DESCRIPTION OF THE DRAWINGS




Referring now to the drawings wherein like elements are numbered alike in the several figures:





FIG. 1

is a representation of a prior art hydraulic power unit within a machine room;





FIG. 2

is a schematic perspective view of a hydraulic elevator system of the invention and illustrating one location for the unit;





FIG. 3

is a perspective exterior view of the hydraulic pump unit of the invention;





FIG. 4

is an enlarged assembled elevation view of a portion of the illustration of

FIG. 2

within circumscription line


3





3


;





FIG. 5

is a perspective view of the hydraulic pump unit of the invention with the outer housing removed to expose internal parts of the invention;





FIG. 6

is a schematic representation of the invention connected to an auxiliary valve block and electronic board in a controller cabinet; and





FIG. 7

is a top plan view of a hoistway illustrating an alternate location for the hydraulic pump unit.











BEST MODE FOR CARRYING OUT THE INVENTION




The invention enables compliance with market desires and emerging industry regulations by eliminating the need for a machine room in hydraulic elevator systems. Referring to

FIG. 2

, the invention locates a new hydraulic power unit


40


in clearance space around elevator car


42


and/or framework


44


. The car


42


and the piston (not shown) are otherwise conventional. Because of the particular construction and configuration of elements within power unit


40


, the unit is small enough to fit in clearance space in the hoistway such as the location in which it is illustrated in FIG.


2


. It should be understood that

FIG. 2

represents but one possible embodiment, other possible embodiments include placement in other clearance spaces within the hoistway.




Referring to

FIGS. 3-5

, the hydraulic power unit


40


of the invention is illustrated in detail. In

FIG. 3

, a vertically oriented tank


50


of unit


40


and associated mounting hardware is shown. Tank


50


comprises sheet material, preferably metal, which is bent or otherwise constructed to rest in a preferably rectangular shape and which is sealed at all side and bottom seams so that it will prevent leaking of the hydraulic fluid (oil) contained therein. A minimum level of oil is represented at broken line


52


and a maximum level is represented at broken line


54


.




Tank


50


is mounted upon tank suspensions


56


which are preferably fastened to a support structure such as a wall through flange


58


. Suspensions


56


provide a further flange


60


which is used to bolt to spacer


62


with fasteners


64


in a preferred embodiment. Spacer


62


is illustrated as a C-channel although it will be understood that other structures may be substituted. Spacer


62


provides a mounting surface


66


through which a fastener


68


extends and upon which a bushing


70


rests. Fastener


68


then extends through a base flange


72


of tank


50


. Another bushing


74


is placed upon fastener


68


and then a nut


76


is tightened thereupon. The arrangement is preferred to provide vibration damping for the unit


40


which reduces noise emissions. Further reducing noise emissions are cover


78


which is mounted atop tank


50


and provides noise insulation for a valve block housed herewith.




Referring to

FIG. 5

, the internal components of unit


40


are illustrated. A valve block


80


is mounted inside of cover


78


. Such valve blocks are commercially available from Otis Elevator Company, CEAM via pradazzo N. 4/2, 40012 Calderara di Reno (BO) ITALIA. Block


80


is mounted on plate


82


. Plate


82


includes a plurality of orifices for through passage of a plurality of draining pipes


84


which drain oil from piloting valves during operation of the power unit


40


. Plate


82


also supports discharge hose


86


which discharges oil from an acceleration spool and a pressure relief valve which are internal to block


80


and known to the art. In discussing

FIG. 5

the relative terms “above” and “below” are intended only to relate to the drawing figure and not to imply any limitation to location of components of the invention. Below plate


82


is positioned motor tank


88


which is attached to plate


82


in spaced relation by arms


90


. In a preferred embodiment, arms


90


are attached to motor tank


88


with bushings


92


to reduce vibration and associated noise.




Tank


88


is preferably constructed of sheet metal material and in a preferred embodiment is cylindrical in shape. The tank is sized appropriately to contain the motor


93


being employed for the application so as to maintain the motor immersed in an oil or other hydraulic fluid at all times. The motor is attached to a pump


94


which extends from the bottom of motor tank


88


to the bottom of tank


50


(FIG.


3


). Motor tank


88


and plate


82


along with all related components are supported within tank


50


by feet


96


and


98


which are preferably bushed with a vibration absorbent bushing


100


. Finally, a high pressure line


102


is visible in the drawing in exploded form which in operation ferrys high pressure fluid from pump


94


to valve block


80


. The high pressure fluid (oil) is then distributed to the piston of the elevator through the auxiliary valve block


104


and through line


106


(see FIG.


6


). A return line


108


returns fluid from the piston to the tank


50


.




Because of motor tank


88


, the motor


93


always remains submerged in oil. The oil in the motor tank


88


is cooled by the bleed oil from discharge hose


86


and draining pipes


84


during descent of the elevator car and by bleed oil from the pump into tank


88


during upward movement of the elevator car


42


. More specifically, upon an elevator car call, the motor is activated and the pump pressurizes the fluid headed for the piston. Some of this pressurized fluid bleeds from the pump


94


into the motor tank


88


due to the intentional lack of a seal at the interface of the motor


93


and pump


94


. Preferably, only a busing is installed at this interface to maintain operating parameters of the pump but to facilitate the bleed. The bleed oil is cooler than the oil in motor tank


88


. Since the bleed oil during this phase of operation bleeds in from the bottom of tank


88


and because the oil is cooler, the warmer oil in the motor tank


88


spills over the top thereof. The oil in the motor tank


88


is thus replaced by the cooler bleed oil and cools the motor. During the down operation, bleed off oil from the valve block, as stated above, enters the top of the motor tank


88


thus also cooling the motor. Based upon testing, the temperature of the oil in the motor tank


88


remains at or below 70° C. and the motor (not shown remains at or below 100° C. This is because the bleed oil is cooler than the indicated temperature when introduced to motor tank


88


. The oil is cooler because of enviromental cooling thereof in the outer tank and the piston. The operation of the car itself due to wind currents it created in the hoistway assists in the environmental cooling.




The invention allows virtually all of the oil in outer tank


50


to be used to lift the elevator car while still keeping the motor submerged in its own motor tank


88


. For this reason, less total oil is necessary and a smaller effective exterior dimension is achieved. Thus the power unit


40


is fittable into clearance spaces in the hoistway and does not require the construction of a machine room.




Another embodiment of the invention is illustrated in

FIG. 7

from a top plan view. In this embodiment the power unit


40


is located at the side of the elevator car


110


between guide rails


112


and brackets


114


. One of skill in the art will appreciate the otherwise conventional aspects of the drawing which include rollers or sliding shoes


116


; piston


118


; pully


120


; piston bracket


122


; ropes fixing plate


124


; uprights


126


and car doors


128


.




Another feature of the invention significantly improves the convenience of a rescue hand pump by locating the same in a control cabinet


130


near the elevator door on one of the floors serviced by the elevator system. The location avoids the need to enter the hoistway and additionally will allow for a visual confirmation of location of elevator car


42


by the person operating the hand pump. To enable the benefits of this aspect of the invention reference is made to

FIGS. 2 and 6

. Within control cabinet


130


is auxiliary block


104


including a hand pump


132


for lifting the elevator car to a next higher floor and, alternatively, a valve


134


to allow fluid in the elevator piston to move back into the reservoir to allow the elevator car to descend to the next floor. In order to so locate the auxiliary valve block


104


, hoses


106


and


108


are provided as shown. In addition hereto, and because of the remote location of the pump


132


provision must be made for priming the pump during installation thereof. Expediently, this is provided for by a three way valve located at the interface between hose


106


and valve block


80


which can be positioned to pump fluid into hose


106


and back through hose


108


for initial priming. This is done by signaling an elevator car call with the valve in the prime position. Fluid pressurized by the pump will thus be urged through the hoses


106


and


108


and through the auxiliary block


104


. Subsequent to this operation the valve is set to normal operation and it does not need to be activated again unless disassembly of the rescue pump assembly is necessary for maintenance or repair.




Although the invention has been shown and described with respect to exemplary embodiments thereof; it should be understood by those skilled in the art that various changes, omissions, and additions may be made thereto, without departing from the spirit and scope of the invention.



Claims
  • 1. An hydraulic elevator power unit comprising:a vertically oriented elongated outer tank; a motor taken mounted within said outer tank; a motor disposed within said motor tank; and a pump operably connected to said motor.
  • 2. A hydraulic elevator power unit as claimed in claim 1 wherein said unit further comprises a valve block mounted to said outer tank.
  • 3. A hydraulic elevator power unit as claimed in claim 2 wherein said unit includes an insulative cover disposed over said valve block.
  • 4. A hydraulic elevator power unit as claimed in claim 1 wherein said unit further includes at least one fluid path from said valve block to said motor tank.
  • 5. A hydraulic elevator power unit as claimed in claim 1 wherein said unit contains a hydraulic fluid whose level is variable within said outer tank and is fixed within said motor tank.
US Referenced Citations (4)
Number Name Date Kind
3764233 Strickland Oct 1973 A
4785915 Shah et al. Nov 1988 A
5078236 Shimoaki et al. Jan 1992 A
6029448 Hubson Feb 2000 A
Foreign Referenced Citations (4)
Number Date Country
0680921 May 1995 EP
02296497 Oct 1990 JP
07114228 May 1995 JP
332698 Feb 1971 SE