The invention relates to hydraulic elevators. More particularly,
the invention relates to a pump and tank for a hydraulic power unit.
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 Figure 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 modern 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.
The above-identified drawbacks of the priorart are overcome
or allenated by the hydraulic power unit of the invention in its various aspects.
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 preferably provides an insulated cover for
the valve block assembly thus ameliorating the noise transmitted through the valve
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 preferably locates the 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 preferably includes a rescue pump located
The present invention will now be described, by way of
example only, with reference to the accompanying drawings in which:
- FIGURE 1 is a representation of a prior art hydraulic power unit within a machine
- FIGURE 2 is a schematic perspective view of a hydraulic elevator system of the
invention and illustrating one location for the unit;
- FIGURE 3 is a perspective exterior view of the hydraulic pump unit of the invention;
- FIGURE 4 is an enlarged assembled elevation view of a portion of the illustration
of FIGURE 2 within circumscription line 3-3;
- FIGURE 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;
- FIGURE 6 is a schematic representation of the invention connected to an auxiliary
valve block and electronic board in a controller cabinet; and
- FIGURE 7 is a top plan view of a hoistway illustrating an alternate location
for the hydraulic pump unit.
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 FIGURE 2, the invention locates a new hydraulic power
unit 40 in clearance space around elevator car 42 and/or framework 44. Car 46 and
piston 48 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 the figure. It should be understood that the figure represents but one possible
embodiment, other possible embodiments include placement in other clearance spaces
within the hoistway.
Referring to FIGURES 3-5, the hydraulic power unit 40 of
the invention is illustrated in detail. In FIGURE 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 FIGURE 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 FIGURE 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 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 what would be the
bottom of tank 50 if shown in this drawing. 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 FIGURE 6). A return line 108 returns fluid from the
piston to the tank 50.
Because of motor tank 88, the motor (not shown) 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 and pump 94. Preferably, only a bushing 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 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 temperatures when introduced to motor tank 88.
The oil is cooler because of environmental cooling thereof in the outer tank and
the piston. The operation of the car itself due to wind currents it creates 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
Another embodiment of the invention is illustrated in FIGURE
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 FIGURES 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 signalling 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 scope of the invention.