Note: Descriptions are shown in the official language in which they were submitted.
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Description
Holeless Hydraulic Elevator With
Improved Car Frame
Technical Field
5This invention relates to elevators and
particularly to holeless, hydraulic elevators.
~ackground ~rt
Short rise hydraulic elevators are well known in
the art. Certain of such elevators comprise a car
powered vertically by an hydraulic jack exposed
beneath the elevator car in a hole beneath the
hoistway. Provision o~ such a hole to accommodate the
jack represents a significant portion of the cost of
the erection of such an hydraulic elevator. In an
effort to reduce the construction costs associated
with such prior art elevators, holeless hydraulic
elevators have been developed. In such a holeless
elevator the car is powered by one or more hydraulic
jacks, the cylinders of which are disposed generally
alongside the car rather than beneath it, the lower
ends of the jacks being received within a shallow pit
at the bottom of the hoistway rather than in a deeper
hole as described hereinabove. While the elimination
of holes in hydraulic elevators has reduced the
construction costs thereof, it has been determined
that state of the art holeless hydraulic elevators
still exhibit various shortcomings.
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A number of such shortcomings in present day
holeless hydraulic elevators are associated with the
elevator car frame which in some instances employs at
the sides thereof, compressively loaded uprights with
diagonal braces connected between the uprights and the
car platform. It has been found that such car frames
are not only complex, requiring rod fixtures on both
the upright and car platform as well as means for
adjusting rod tension, but are quite heavy as well.
Moreover, in such a frame structure, various
components of the frame tend to be loaded in
compression and bending which adversely affect the
stability of the car under operating conditions and
require accommodation by heavy structural members
thereby further contributing to the weight of the
frame. Such car frames also tend to militate against
ease of serviceability of the jacks since the upright
is often in a position which interferes with
maintenance on the jack disposed adjacent thereto.
Prior art hydraulic elevators also exhibit
various deficiencies in the support and stabilization
of the car by the jacks and guide rails employed
therein. Most of such deficiencies are attributable
to the somewhat common approach of asymmetric support
of the car by the jacks wherein, the jacks support the
car by connection to the sides of the car frame either
forwardly or rearwardly of the center thereof. Thus,
the weight of the car applies bending moments to the
jacks and guide rails, thereby requiring burying of
the lower ends of the jacks within the ground with an
attendant risk galvanic corrosion of the jack
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cylinders as well as requiring heavy rails which add
to the expense to the elevator in the cost of both
materials therefor and erection thereof. Moreoever,
prior art hydraulic elevators often fail to provide
adequate yet economical means for limiting the
overtravel of the elevator car (due to, for example, a
malfunction of the hydraulic control system) while
dissipating the kinetic energy of the car during such
overtravel conditions.
The above deficiencies associated with prior art
hydraulic elevators combined with the desirability of
mechanically simplieying such elevators while at the
same time reducing the weight thereof has lead to the
present invention.
Disclosure of Invention
It is therefore an object of the present
invention to provide an hydraulic elevator of enhanced
simplicity and stability and which is light in weight.
It is another object of the present invention to
provide an hydraulic elevator which is compact and
easily serviceable.
It is another object of the present invention to
provide an hydraulic elevator characterized by an
enhanced ease in the erection thereof.
It is another object of the present invention to
provide an hydraulic elevator wherein overtravel o
the elevator car due to malfunction of the hydraulic
system is safely and simply limited.
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In accordance with the present invention, an
hydraulic elevator employs a car frame including side
frame assemblies, each of which comprises a pair of oblique,
upwardly convergent bilaterally rigid braces fixed at lower
ends thereof to the car platform and at upper ends
thereof to the free end of the plunger rod of an
hydraulic jack, thereby defining a tensiley loaded,
lightweight A-frame. Such a frame assembly minimizes
bending and compression loads in the frame thereby
enhancing the mechanical stability thereof. ~ach of a
pair of hydraulic jacks which power the elevator car
is receivable interiorly of the A-frame. The upper
ends of the oblique braces (which may be tubular) are
connected by fasteners such as bolts to the plunger
rod by a short bracket of generally U-shaped cross
section, the bolts being placed in double shear for
increased strength in that connection. The improved
car frame also includes a lightweight platform formed
by a planar array of tubular beams supporting a floor
portion and a guide shoe laterally offset from the top
of the car frame by a bracket on which hydraulic
control switches are also conveniently mounted.
Brief Description of Drawings
Fig. 1 is an isometric view of a preferred
embodiment of the hydraulic elevator of the present
invention, portions of the elevator being either
broken away or removed entirely to show details of the
construction thereof;
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Fig. 2 is a side elevation in partial section of
one of the hydraulic jacks employed with the elevator
of the present invention;
Fig. 3 is a view taken in the direction of line
3-3 of Fig. 2;
Fig. 4 is an enlarged, fra~mentary, elevation of
the connection between one of the braces employed in
the frame of the elevator car and the output member of
the hydrauIic jack and taken in the direction of line
4-4 of Fig. l;
Fig. 5 is an isometric view similar to Fig. 1,
but showing an alternate embodiment of the hydraulic
elevator in which lower portions of the guide rails
thereof have been eliminated; and
Fig. 6 is a top plan view in partial section of a
portion of the car frame a guide shoe carried thereby,
and an associated hydraulic jack, taken along line 6-6
of Fig. 5.
Best Mode for Carrying Out the Invention and
Industrial Applicability Thereof
Referring to Fig. 1, an hydraulic elevator 10 is
disposed within a hoistway 15 including a sidewall
structure 20 and a lower pit 25. The elevator itself
comprises a car 30 including a frame 35, a sidewall
structure ~which for clarity is not illustrated) and a
platform 40. The car is powered by a pair of upright
jacks 45 disposed on opposite sides of the car and
supported within hoistway 15 on the floor of pit 25.
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Car frame 35 comprises a pair of opposed side
frame assemblies each including a pair of oblique
upwardly convergent braces 55 fixed at lower ends
thereof to the car platform at opposed sides thereo~. The
braces may be of any known bilaterally rigid structural shape,
in the preferred embodiment the braces being-formed from
tubular steel for strength and lightness. The lower
ends of the braces are attached to the platform by
riveted, bolted, or similar connections to L-shaped
1~ brackets 60 welded or similarly attached to the sides
of the platform. The upper ends of the braces are
connected together by a rigidly bolted or riveted
connection to opposite ends of bracket 65 of generally
U-shaped cross section, the sides of bracket 65 each
including a cutout 70 which accommodates the head of
jack 45 therewithin. The connection between braces 55
and bracket 65 is shown in greater detail in Fig. 4.
As shown therein, each brace is received within the
interior of the bracket outwardly of the medial
portion thereof which is connected by bolt 75 to the
jack. As illustrated, three bolts 85 pass through
both sides of the bracket and each brace although
greater or lesser numbers of fasteners may be employed
depending upon the capacity of the elevator, the
weight of the car and other relevant factors. As best
seen in Fig. 1, bracket 65 serves to provide a
connection between the jack and the car frame, and it
will thus be appreciated that the connections between
bracket 65 and braces 55 are loaded by the weight of
the car. However, the tubular shape of the braces and
the U-shaped cross section of bracket 65 cause each of
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bolts 85 to be loaded in double shear for enhancing
the strength of the connection. ~urthermore, it will
be appreciated that braces 55 are loaded entirely in
tension which enhances the stability of the car and
eliminates any need for more massive structural
components required to accommodate compressive and/or
bending modes of loading.
Referring again to Fig. 1, the side frame
assemblies are connected together by a cross head 90
comprising a pair of generally parallel channel
members 95 connected by bolts, rivets or the like at
opposite ends thereof to inwardly extending plates 100
attached to braces 55 by a welded or similar
connections thereto. Channels 95 support oblique
brackets 105 and lateral brackets 110 by bolted,
riveted or similar connections thereto, brackets 105
and 110 being connected together at 115 by bolts,
rivets or the like. As illustrated, each lateral
bracket 110 carries an upper guide shoe 120 which
slideably engages a corresponding guide rail 125 of
generally T-shaped cross section which is mounted to a
sidewall of the hoistway. Those skilled in the art
will, of course, recognize that the engagement of
upper guide shoes 120 as well as lower guide shoes 130
(carried by the car frame at the bottom of the
platform thereof) with guide rails 125 provides
additional lateral stability to the car. It will be
seen that brackets 110 function not only as mounts for
the guide shoes but also as mounts for leveling switch
135 including rollers 140 operated by stationary cams
145 mounted on the guide rail. Those skilled in the
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art will, of course, readily appreciate that leveling
switch 135 operated by cam 145 along with leveling
switch 150 operated by cam 155 attached to the
opposite side frame assembly controls hydraulic fluid
flow to and from the jacks for controlIing such
functions as acceleration and deceleration of the car
by the jacks. ~racket 110 in providing a mount for
both guide shoe 120 and leveling switch 135 si~plifies
the overall structure of the car frame by eliminating
the need for separate mounts for these components.
Platform 40 comprises a generally planar array of
tubular beams including a plurality of parallel beams
160 joined at opposite ends thereof ~as by welding or
the like) by a pair of generally parallel beams 165
orthogonally disposed with respect to beams 160. The
platform includes a floor portion 167 overlying the
platform frame and mounted thereto as by screws (not
shown) or the like, the floor portion comprises a
laminar arrangement of a lightweight, structural upper
plate 170 formed from such material as wood,
composite, or an oriented strand wood fiber material
such as that sold by Weyerhaeuser Company under the
mark Structurwood and a metallic lower plate 175
functioning as a fire stop and typically formed from
aluminum, sheet steel, or the like. Such a platform
structure, employing a planar array of tubular beams
and a lightweight floor, substantially reduces the
weight of the platform as compared to the platforms of
prior art elevators thereby reducing the required
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strength and thus the weight of the remainder of the
car frame as well as the hydraulic requirements of the
elevator.
Referring to Fig. 2, each of jacks 45 comprises a
cylinder 200 including a head 205 defined by h~using
members 207 and 208 and a plunger 210 disposed within
: the cylinder for reciprocal movement with respect
thereto in response to changes in pressurizati~n and
draining of the cylinder with hydraulic fluid through
hydraulic lines 215. Plunger 210 is mounted on
connecting rod 220 which extends outwardly o~ cylinder
200 through the head, the upper end of rod 220
including a hole through which bolt 75 is threaded for
connecting the rod to bracket 65.
As set forth hereinabove, in the event of a
malfunction of the hydraulic control system it is
desirable to provide hydraulic elevators with means to
limit overtravel of the car while safely dissipating
the kinetic energy of the car associated with any such
overtravel. In accordance with the present invention,
jack 45 is provided with stop means disposed
: proximally to the cylinder head for limiting
overtravel of the plunger while dissipating the
kinetic energy thereof and means associated with the
plunger for abutment with the stop means. As best
illustrated in Fig. 2, the stop means comprises a hard
impact ring 225 of steel or the like backed by a
resilient urethane ring 230 which is in turn backed by
a hard stop ring 235, In the event that plunger 210
is caused to overtravel upwardly due to an hydraulic
system malfunction, the plunger will abut impac~ ring
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225 which upwardly compresses urethane ring 230
against stop ring 235, thereby eliminating further
plunger overtravel and dissipating the energy of such
overtravel by compression of the urethane ring to
reduce the risk of damage to the jack. Head 220 also
acco~modates a rubber seal 240, a wear ring 245 and
wiper 250 in the usual manner. It will be noted that
since the jack is received interiorly of the oblique
braces 55 and since the guide rails are laterally
offset from the jack, the jack is readily accessable
for ease in maintenance thereof. Moreover, the lack
of interference with the jack by the car frame and
guide rails allows large clearances for head 205 and
thus, the convenient accommodation of the two
rectangular housing members 207 and 2~8 bolted
together at the corners thereof with four bolts 255.
This is to be contrasted with various prior art
elevator jack designs wherein jack head clearances are
so limited that the head must be cylindrical in shape
and of a diameter requiring bolting with as many as 9
to 12 bolts making such a head costly to manufacture
and difficult to service.
Referring again to Fig. 1, as illustrated
therein, jacks 45 are disposed adjacent to the car
platform at medial locations on opposed sides thereof
whereby the car is supported in a generally symmetric
manner thereby reducing rail reactions to loading
thereof and allowing rails of lighter weight than
those of the past to be used. Disposition of the
jacks interiorly of the car frame side assemblies
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(between oblique braces 55) not only renders the jacks
easily serviceable, but provides a more efficient use
of the interior of the hoistway.
Guide rails 125 are mounted at the upper portions
thereof to the hoistway walls with clamps 260 carried
by fixtures 265 bolted to the hoistway walls and at
the lower ends thereof by fastening (such as by
welding) to angle brackets 270 mounted to the floor of
the pit by any suitable means such as bolts and the
like (not shown). The guide rails and jacks are also
fixe~ to the hoistway walls and aligned with each
other by connection to mounting brackets 275 each
comprising a plurality of spaced feet 280 at which the
bracket is secured to the hoistway sidewalls as by
bolting. As shown, the bracket is a unitary structure
in which the feet 280 alternate with fixture portions
(lands) 285 and 290 at which jack and guide rail,
respectively, are connected to the bracket as by
clamping. Since the car is symmetrically supported by
the jacks, the jacks are generally symmetrically
loaded and therefore, the prior art practice of
burying the lower ends of the jacks to accommodate
bending loads thereon is unnecessary. Accordingly,
the lower ends or bases of the jacks are received
within a jack base comprising an upperwardly open,
generally U-shaped channel member 295 closed at the
ends thereof with closure plates 300 fastened thereto
such as by welding, the closure plates being apertured
to receive the jack bases for the alignment and
vertically unrestrained accommodation thereof within
the channel member. Such vertically, unrestrained
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accommodation allows the jacks to freely "jump"
upwardly in the event of overtravel of the car for
further dissipation of the kinetic energy associated
therewith. The jack base also provides a convenient
mount for receptacles 305 which accornmodate buffer
springs 310 on which the platform may rest when
lowered. The receptacles are fixed to the web of the
channel member by any suitable means such as bolts or
the like.
Referring to Figs. 5 and 6, an alternate embodi-
ment of the elevator is shown. In this embodiment the
lower portions o~ guide rails 125 have been
eliminated, the jack cylinders taking the place of the
lower rail portions and the lower slotted guide shoes
lS have been replaced by a guide shoe 300 comprising a U-
shaped bracket 305 carrying rollers 310 at the ends
thereof. Bracket 305 is bolted at 315 to a mounting
member 320 at the bottom of the car platform in
alignment with jack cylinders 200 so that rollers 310
engage the cylinder walls. Thus, with this arrange-
ment, lateral stability of the car at lower positions
thereof is attained by movement of the car along the
jack cylinders without necessitating lower guide
rails, thereby further simplifying the elevator and
rendering the elevator more economical in both
material and assembly costs thereof.
From the foregoing, it will be seen then that the
car frame described herein is simpler than prior art
frames since it requires neither adjustable rods nor
upright members. The frame is more stable than prior
art frarnes since the side supports are loaded in
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tension, without any significant compressive or
bending loads thereon and the joints are rigid, Since
the jacks are generally coplanar with the side frame
assemblies, the elevator is compact and the jacks are
S easily serviceable. The tubular frame floor further
contributes to the lightness of the elevator and the
symmetric support of the car frame by the centrally
disposed jacks allows the use of smaller rails, due to
minimal rail reactions. The symmetric loading of the
jacks also eliminates the need to bury the lower ends
of the jacks thus eliminating the'risk of the galvanic
corrosion of the jack ends due to such burial.
Furthermore, since the jacks do not re~uire burying,
they may rest on the pit floor in a vertically
unrestrained orientation allowing the entire elevator
to "jump" ir the event of car overtravel thereby
contributing with the novel jack head structure to the
elevator's ability to dissipate the kinetic energy
associated with upward overtravel of the car. The
integral guide shoe and leveling switch mounting, the
one piece rail jack bracket and'the jack base further
simplify the manufacture and erection of the elevator.
It should be understood that the invention is not
limited to the particular embodiments shown and
described herein, but that various changes and
modifications may be made without departing from the
spirit and scope of the invention as defined by the
following claims.
Having thus described the invention, what is
claimed is:
