U.S. patent application number 12/495761 was filed with the patent office on 2010-01-07 for rail system for a powered pallet conveyor.
This patent application is currently assigned to ROFA ROSENHEIMER FORGERANLAGEN GMBH. Invention is credited to Bruno MEINZINGER.
Application Number | 20100000440 12/495761 |
Document ID | / |
Family ID | 39825677 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100000440 |
Kind Code |
A1 |
MEINZINGER; Bruno |
January 7, 2010 |
RAIL SYSTEM FOR A POWERED PALLET CONVEYOR
Abstract
A rail system for a powered pallet conveyor, which comprises
alternative pathways having an electric cable provided on at least
one of n parallel rails defining a travel pathway, wherein
n.gtoreq.2, whereby the rail system includes a switch for switching
between m alternative travel pathways, wherein m.gtoreq.2, and
allowing the vehicle to continuously move across the switch after
switching, said switch comprising a first actuator for selectively
positioning (m*n) rigid rail portions bridging the distance between
rail ends at (i) n joining points where the n parallel rails of
each of the m alternative travel pathways subject to switching
converge, and (ii) (m*n) continuation points where each alternative
pathway subject to switching diverges downstream from the joining
points. A second actuator selectively positions [m(n-1)] rigid rail
portions bridging the distance between rail ends, where each
alternative pathway is discontinued downstream from the
corresponding continuation points.
Inventors: |
MEINZINGER; Bruno; (Munchen,
DE) |
Correspondence
Address: |
GREENBERG TRAURIG LLP (LA)
2450 COLORADO AVENUE, SUITE 400E, INTELLECTUAL PROPERTY DEPARTMENT
SANTA MONICA
CA
90404
US
|
Assignee: |
ROFA ROSENHEIMER FORGERANLAGEN
GMBH
Kolbermoor
DE
|
Family ID: |
39825677 |
Appl. No.: |
12/495761 |
Filed: |
June 30, 2009 |
Current U.S.
Class: |
104/102 |
Current CPC
Class: |
E01B 7/00 20130101; E01B
23/06 20130101 |
Class at
Publication: |
104/102 |
International
Class: |
E01B 25/15 20060101
E01B025/15 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 7, 2008 |
EP |
EP08012241.9 |
Claims
1: A rail system for a powered pallet conveyor, which comprises
alternative pathways for a vehicle traveling along an electric
cable provided on at least one of n parallel rails defining a
travel pathway, wherein n.gtoreq.2, whereby the rail system
includes a switch for switching between m alternative travel
pathways, wherein m.gtoreq.2, and allowing the vehicle to
continuously move across the switch after switching, said switch
comprising: (a) a first actuator for selectively positioning (m*n)
rigid rail portions bridging the distance between rail ends
optionally holding cable ends at: (i) n joining points where the n
parallel rails of each of the m alternative travel pathways subject
to switching converge, and (ii) (m*n) continuation points where
each alternative pathway subject to switching diverges downstream
from the joining points, and (b) a second actuator for selectively
positioning [m(n-1)] rigid rail portions bridging the distance
between rail ends optionally holding cable ends at crossing
portions, where each alternative pathway subject to switching is
discontinued downstream from the corresponding continuation points;
whereby the positioning of a set of n rigid rail portions by the
first actuator and the positioning of (n-1) rigid rail portions by
the second actuator provides a travel pathway allowing the vehicle
to continuously travel across the switch along the electric cable
means provided on at least one of n parallel rails defining the
travel pathway.
2: The rail system according to claim 1, wherein n is 2.
3: The rail system according to either claim 1 or 2, wherein m is
2.
4: The rail system according to claim 1 or 2, wherein the first
actuator is a shifting frame.
5: The rail system according to claim 1 or 2, wherein the second
actuator is a shifting frame.
6: The rail system according to claim 1 or 2, wherein the pathways
are mounted on the floor.
7: The rail system according to claim 1 or 2, further comprising
determining the position of a vehicle and communicating the
position to a control.
8: A process for operating a switch of a rail system for a powered
pallet conveyor as defined by claim 1, which comprises the steps
of: (a) selecting one of n alternative pathways; (b) positioning n
rigid rail portions for bridging the distance between: (i) n
joining points where the m alternative travel pathways subject to
switching coincide, and (ii) n continuation points of the selected
travel pathway downstream from the joining points; and (c)
positioning n-1 rigid rail portions for bridging the distance
between rail ends optionally holding cable ends at crossing
portions where each alternative pathway subject to switching is
discontinued downstream from the corresponding continuation points;
thereby providing the selected pathway allowing the vehicle to
travel along an electric cable provided along at least one of n
parallel rails defining the selected pathway.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to European Patent
Application No. EP 08 012 241.9, filed Jul. 7, 2008, the contents
of which are incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The present invention provides a rail system for a powered
pallet conveyor. Moreover, the present invention provides a process
for operating a switch of a rail system for a powered pallet
conveyor. The present invention uses a switch means for switching
between m alternative travel pathways, wherein m.gtoreq.2, and
allowing the vehicle to continuously move across the switch after
switching.
BACKGROUND OF THE INVENTION
[0003] Powered pallet conveyors are known. Powered pallet conveyors
may be used for loading or unloading trucks and trailers with
product on pallets or in containers. Powered pallet conveyors may
comprise a vehicle and a rail system which defines pathways on
which the vehicle may travel.
[0004] Conventional rail systems for a powered pallet conveyor may
comprise switch means for allowing the vehicle to travel on
alternative pathways. U.S. Pat. No. 4,498,399 discloses a free line
switch arrangement for power-and-free trolley conveyors wherein the
free line comprises two rails. Two other types of switch means have
been considered, namely a quadro switch and a rotation switch.
[0005] A quadro switch, as shown in FIG. 4, is operated by first
positioning the vehicle on the switch so that pivotable wheels of
the vehicle are placed on rotatable rail portions. Subsequently,
the rotatable rail portions are rotated independently so that the
wheels of the vehicle are oriented along and guided to the new
travel pathway.
[0006] A rotation switch, as shown in FIG. 5, is also operated by
first positioning the vehicle on the switch so that the vehicle may
be rotated as a whole on a rotatable turntable. Subsequently, the
rotatable turntable is rotated so that the vehicle is oriented
along and guided to the new travel pathway.
[0007] Both switch means are unsatisfactory in that the vehicle
cannot travel continuously across the switching means without
stopping. As a consequence, the presence of a switching means
results in a limitation of the maximum speed by which the powered
pallet conveyor is capable of completing a task. Limitations
imposed by the switching means are even greater in cases when more
than one switching is required per travel of the powered pallet
conveyor.
[0008] Furthermore, conventional switching means have significant
space requirements. Moreover, vehicles subjected to frequent
acceleration/deceleration suffer from increased wear and earlier
failure so that maintenance costs are high.
SUMMARY OF THE INVENTION
[0009] It is the problem of the present invention to provide a rail
system for a powered pallet conveyor which allows the vehicle to
travel continuously across the switching means without stopping
while the switching means has reduced space requirements and does
not subject vehicles to acceleration/deceleration during switching
so that wear is reduced and early failure of the vehicle and high
maintenance costs are avoided.
[0010] This problem is solved according to the present invention by
a rail system for a powered pallet conveyor, which comprises
alternative pathways for a vehicle traveling along an electric
cable means provided on at least one of n parallel rail means
defining a travel pathway, wherein n.gtoreq.2, whereby the rail
system is characterized by a switch means for switching between m
alternative travel pathways, wherein m.gtoreq.2, and allowing the
vehicle to continuously move across the switch after switching,
said switch means comprising
[0011] (a) a first actuating means for selectively positioning
(m*n) rigid rail portions bridging the distance between rail ends
optionally holding cable ends at [0012] (i) n joining points where
the n parallel rail means of each of the m alternative travel
pathways subject to switching converge, and [0013] (ii) (m*n)
continuation points where each alternative pathway subject to
switching diverges downstream from the joining points, and
[0014] (b) a second actuating means for selectively positioning
[m(n-1)] rigid rail portions bridging the distance between rail
ends optionally holding cable ends at crossing portions, where each
alternative pathway subject to switching is discontinued downstream
from the corresponding continuation points,
[0015] whereby the positioning of a set of n rigid rail portions by
the first actuating means and the positioning of (n-1) rigid rail
portions by the second actuating means provides a travel pathway
allowing the vehicle to continuously travel across the switch along
the electric cable means provided on at least one of n parallel
rail means defining the travel pathway.
[0016] Moreover, the present invention provides a process for
operating a switch of a rail system for a powered pallet conveyor
according to the invention, which comprises the steps of
[0017] (a) selecting one of n alternative pathways;
[0018] (b) positioning n rigid rail portions for bridging the
distance between [0019] (i) n joining points where the m
alternative travel pathways subject to switching coincide, and
[0020] (ii) n continuation points of the selected travel pathway
downstream from the joining points,
[0021] (c) positioning n-1 rigid rail portions for bridging the
distance between rail ends optionally holding cable ends at
crossing portions where each alternative pathway subject to
switching is discontinued downstream from the corresponding
continuation points,
[0022] thereby providing the selected pathway allowing the vehicle
to travel along an electric cable means provided along at least one
of n parallel rail means defining the selected pathway.
DESCRIPTION OF THE FIGURES
[0023] FIG. 1 shows a plan projection of a specific embodiment of
the rail system, wherein the first and second actuating means are
positioned so as to allow a vehicle to travel along an electric
cable means provided along at least one of the parallel rail means
defining the pathway A.
[0024] FIG. 2 shows a plan projection of the rail system shown in
FIG. 1, which is instead set up with the first and second actuating
means positioned so as to allow a vehicle to travel along an
electric cable means provided along at least one of the parallel
rail means defining the pathway B.
[0025] FIG. 3 shows an orthographic projection of the rail system
shown in FIG. 1, which is instead set up with the rigid rail
portions of the first actuating means selectively defining the
pathway B, except that the second actuating means has not been
switched to allow a vehicle to travel through the crossing point
and further along the pathway B.
[0026] FIG. 4 shows a quadro switch of the prior art.
[0027] FIG. 5 shows a rotation switch of the prior art.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0028] The present invention relates to a rail system for a powered
pallet conveyor. The rail system comprises alternative pathways for
a vehicle conveying a pallet along rails. A pathway in general
means a connection between a starting point of a vehicle and a
destination point of the vehicle which is provided by rails.
[0029] The powered pallet conveyor vehicle may be either loaded
with a pallet or not. The vehicle conveys a pallet, either loaded
or empty, on a pathway of the rail system. The pallet may be
conveyed along the rail system with reduced frictional resistance
by the use of wheels. The wheels may be attached to the vehicle by
means of a bogey or bearing system and/or to the rails, so that
they function as rollers or skatewheels. The wheels additionally
serve to guide the vehicle along the rails and/or effect conveyance
of the pallet.
[0030] The vehicle is powered by electrical potential energy,
wherein an electric motor or motors convert the potential energy
into movement of the vehicle in a particular direction along an
alternative pathway of the powered pallet conveyor. The motor may
be attached to the vehicle, wherein all or a selection of the
wheels of said vehicle are driven by said motor. However, in the
case where the conveyor comprises a rail system with wheels
(rollers) attached to the rails, the motors may instead be attached
to the rail system and power all or a selection of the wheels of
the rails.
[0031] The rail system comprises alternative pathways for a vehicle
traveling along an electric cable means. The electric cable means
is provided on at least one of n parallel rail means defining a
travel pathway, wherein n.gtoreq.2. Thus, a travel pathway is
defined by two or more parallel rails, at least one of which
carries an electric cable. When n=2, the travel pathway has two
parallel rails, either one or both of the rails may carry an
electric cable. The electric cable means is a cable capable of
carrying electric current. The electric current may be used to
either relay information or provide energy for powering the
conveyor.
[0032] Thus, the electric cable comprises an electrically
conductive wire, either in the form of a solid wire or woven
strands. The electrically conductive wire comprises a metal
selected from the list including copper, aluminum, gold and silver,
either singly or in combination. The wire may be jacketed in an
electrically insulative material such as polyethylene or
polyvinylchloride. Further jacketing with mineral insulation,
fiberglass armor, helical steel tape, aluminum armor, lead armor,
woven bronze wire or woven steel wire may be employed to protect
the cable. Alternatively, multiple wires, each optionally
insulated, may be housed in the electrically insulative jacket.
[0033] The rails of the rail system comprise fixed (non-moveable)
portions of rail, as well as the rigid rail portions of the first
and second actuating means that may be selectively positioned so as
to bridge the fixed portions of rail. The fixed portions of rail
may be defined as those rails which are not rigid rail portions of
the first or second actuating means. Selective positioning of the
rigid rail portions of the first and second actuating means so as
to comprise n parallel rail means defining a travel pathway,
results in the rails of the rail system comprising a means for
conveying and guiding the vehicle on a pathway of the rail system.
The rails may additionally comprise at least part of the means for
driving the vehicle, such as the rack of a rack and pinion. The
rails may, furthermore, comprise a means for conducting
electricity, such as an electrically conductive "third rail" system
for electrifying the rail system.
[0034] Material suitable for the construction of the rails includes
metals, alloys and polymers, used singly or in combination. The
rails may comprise any of the metals selected from iron, copper,
aluminum, tin, zinc, titanium, lead, manganese, chromium, vanadium
and tungsten, either singly or in combination. In a further
embodiment, the rails may comprise any of the alloys selected from
steel, brass, bronze, Hastelloy, Electrum, Cupronickel and
Duralumin. Optionally, the rails may comprise a polymer such as
polyethylene, polystyrene, nylon and teflon, either singly or in
combination. Particular combinations of these materials as
composites, laminates, impregnates or coated materials may be used
to provide rails with specific properties. For example, the rails
may comprise a hybrid material such as steel laminated with
aluminum which is not only capable of withstanding the stresses
involved in conveying and guiding a vehicle along alternative
pathways, but also is highly conductive. Alternatively, the rails
may comprise iron or steel that is coated or laminated with a
teflon so as to reduce friction and wear. Alternatively, the rails
may comprise an electrically conductive material such as brass or a
metal coated polymer, so as to themselves form an electric cable
means along the travel pathway.
[0035] Each rail may have a profile which is a particular shape in
cross section. In a preferred embodiment, the cross section may be
an I- (or H-) shape, a T-shape, an L-shape, a U-shape or a
rectangular shape. Variations on these profiles, such as the
asymmetrical I-beam, flat-bottomed, bullhead, single parallel,
parallel, grooved rail, flanged rail or bridge rail profiles may be
employed, either singly or in combination. Most preferred is the
embodiment in which the rail is an I-shape in cross section.
[0036] The rail means defining a travel pathway comprises parallel
rails. Parallel rails are rails which are equidistant from one
another (wherein the minimum distance between rails is essentially
the same at any given position along the length of said rails). The
rail system of the present invention comprises at least two
alternative travel pathways each comprising at least two such
parallel rail means subject to switching. Each rail means is
comprised of at least two fixed sections, optionally joined to at
least one moveable section (rigid rail portion) attached to an
actuating means of the rail system.
[0037] Specifically, the rail system is characterized by a switch
means. The switch means (a rail switch or rail points) is for
switching between m alternative travel pathways, wherein
m.gtoreq.2. When m=2, the rail system allows for the powered pallet
to be conveyed along one of two alternative travel pathways
downstream from a given position along the travel pathway subject
to switching. Similarly, when m=3 or greater, one of three or more
alternative travel pathways downstream of a given position along
the travel pathway may be selected for.
[0038] In a preferred embodiment, the rail system of the present
invention may comprise a means for determining the position of a
vehicle and communicating the position to a control means. Indeed,
selection of a particular travel pathway and control of the rail
system may be achieved manually or automatically. In the case where
the rail system is controlled automatically, a programmable logic
controller (PLC) may be used. The PLC electronically controls how
individual sections of the rail system interact with the vehicle,
and, hence, pallet, being conveyed. In particular, the PLC controls
the positioning of the first and second actuating means in relation
to the vehicle. Furthermore, the PLC controls the movement and
positioning of the vehicle in relation to the rail system. The PLC
is able to convey a vehicle through multiple rail systems of the
invention. Moreover, the PLC is also able to convey multiple
vehicles through either an individual rail system or multiple rail
systems of the invention.
[0039] Electronic control of how individual sections of the rail
system interact with the vehicle may be achieved by the use of
rails which are capable of carrying electric current. The movement
of the vehicle may also induce electric current. The electric
current may be relayed along the rail and thereby provide
information as to the location of the vehicle on the pathway.
Alternatively, the rail may carry current for driving the actuating
means and/or powering the vehicle.
[0040] Selection of a particular travel pathway is made prior to
the vehicle reaching the alternative pathways. Specifically, the
switch means for switching between m alternative travel pathways,
wherein m.gtoreq.2, allows the vehicle to continuously move across
the switch after switching. Accordingly, a travel pathway allowing
the vehicle to continuously travel across the switch on at least
one of n parallel rail means defining the travel pathway is
provided in advance of said vehicle reaching said switch. With
switching made downstream of the vehicle, the vehicle need neither
stop nor slow down for selection to take place.
[0041] In comparison, conventional switch processes such as that of
the quadro switch or rotation switch (FIGS. 4 and 5, respectively)
require that the vehicle stops on the switch in order for selection
of a pathway to occur, prior to then moving along that particular
pathway. This translates to a cumulative loss of time, not just as
a result of the time required for switching, but also that
associated with the acceleration/deceleration process. Thus, the
present invention provides a rail system which conserves time and
therefore operates with greater efficiency of conveyance.
[0042] Furthermore, switch processes such as that of the quadro
switch or rotation switch have the disadvantage that the forces
involved in the acceleration/deceleration process lead to wear on
the vehicle and rail means. Additionally, the forces involved in
switching whilst the vehicle is stationary on the switch similarly
may lead to increased wear on the switch mechanism. The present
invention overcomes such disadvantages by dispensing with the need
for stopping and starting the vehicle and by effecting the
switching and, thus, provision of a travel pathway in advance of
the vehicle reaching said switch. Accordingly, the lifetime of not
only the rail system, but also the vehicle and rail means, as well
as the associated means of driving the rail system and vehicle, is
increased. This leads to a reduction in the costs and time
associated with maintenance of the rail system.
[0043] Switch processes such as that of the quadro switch or
rotation switch have considerable space requirements, particularly
when it is intended for multiple pathways to be provided. Whilst
the quadro switch would appear to be an exception in this regard,
this system can only comprise travel pathways that intersect each
other at a fixed angle, typically 90 degrees. In order to minimize
the number of switch process for a given travel pathway made, for
example, of right-angle intersections, extended lengths of rail and
hence increased amounts of space must be used. The space
requirements associated with a rotation switch are less
considerable, but an increase in the number of alternative travel
pathways provided must, necessarily, be associated with an increase
in the circumference, and hence diameter, of the rotatable
turntable. In contrast, the rail system of the present invention is
relatively compact and is capable of providing multiple travel
pathways in a confined space.
[0044] This is achieved by said switch means comprising (a) a first
actuating means and (b) a second actuating means. The first
actuating means and second actuating means may be operated
simultaneously or at different times. Furthermore, the first
actuating means and second actuating means may be operated
independently or non-independently of one another. In a preferred
embodiment, the first actuating means is a shifting frame. In a
further preferred embodiment, the second actuating means is a
shifting frame. A shifting frame is a moveable framework upon which
the rigid rail portions of the actuating means are firmly attached.
The shifting frame may be shifted to align different sets of the
rigid rail portions of the actuating means with fixed portions of
the rail in order to allow the vehicle to travel across the
actuating means.
[0045] The switch comprises a first actuating means for selectively
positioning (m*n) rigid rail portions bridging the distance between
rail ends optionally holding cable ends at
[0046] (i) n joining points, and
[0047] (ii) (m*n) continuation points.
[0048] The n joining points are where the n parallel rail means of
each of the m alternative travel pathways subject to switching
converge. The (m*n) continuation points are where each alternative
pathway subject to switching diverges downstream from the joining
points. Thus, the first actuating means selectively positions a
subset of n of the (m*n) rigid rail portions of the first actuating
means between the n joining points and a subset of n of the n
continuation points, so as to link the fixed portions of rail with
the rigid rail portions, thereby allowing the vehicle to travel
across the first actuating means.
[0049] The switch additionally comprises a second actuating means
for selectively positioning [m(n-1)] rigid rail portions bridging
the distance between rail ends optionally holding cable ends at
crossing portions where each alternative pathway subject to
switching is discontinued downstream from the corresponding
continuation points. Thus, the second actuating means selectively
positions a subset of (n-1) of the [m(n-1)] rigid rail portions of
the second actuating means between a subset of 2(n-1) of the rail
ends at the crossing portions, so as to link the fixed portions of
rail with the rigid rail portions, thereby allowing the vehicle to
travel across the second actuating means.
[0050] The spatial relationship between the joining points,
continuation points and crossing points is described as follows.
The joining points are defined by the locations where the m
alternative travel paths subject to switching coincide or diverge.
The continuation points are located downstream from the joining
points along the selected travel path. Specifically, the
continuation points are located on the first actuating means at
positions distant from the n joining points along each of the
alternative travel pathways subject to switching. Furthermore, the
crossing points are located at positions distant from the rigid
rail portions of the first actuating means along each of the
alternative travel pathways subject to switching. Thus, the
positioning of a set of n rigid rail portions by the first
actuating means and the positioning of (n-1) rigid rail portions by
the second actuating means provides a travel pathway allowing the
vehicle to continuously travel across the switch along the electric
cable means provided on at least one of n parallel rail means
defining the travel pathway.
[0051] The rail system of the present invention may be supported by
a system of sleepers or cross ties, or mounted directly on the
floor, on an elevated base, overhead or any of a combination of
these. In a preferred embodiment, the pathways are mounted on the
floor.
[0052] The rail system may comprise horizontal pathways, inclined
pathways and/or vertical pathways. In the case where pathways
deviate from the horizontal, it may be necessary to use a means for
driving the vehicle, such as a rack and pinion, which can overcome
the issues associated with operation on gradients.
[0053] A specific embodiment of the rail system of the present
invention is shown in FIG. 1, wherein n=2 and m=2. The rail system
comprises a first actuating means (1) for selectively positioning
(m*n)=4 rigid rail portions (1a, 1b) bridging the distance between
rail ends optionally holding cable ends at the n=2 joining points
(3) and at the (m*n)=4 continuation points (4a, 4b). The rail
system additionally comprises a second actuating means (2) for
selectively positioning [m(n-1)]=2 rigid rail portions (2a, 2b)
bridging the distance between rail ends optionally holding cable
ends at crossing portions (5a, 5b), where each alternative pathway
subject to switching is discontinued downstream from the
corresponding continuation points (4a, 4b). The setup of the rail
system shown allows for a vehicle to convey a pallet along the
travel pathway A. Travel pathway B is not amenable to conveying a
pallet, since the joining points (3) and continuation points (4b)
are not linked by the rigid rail portions (1b) of the first
actuating means (1). Furthermore, the rail ends optionally holding
cable ends at the crossing portions (5b) are not linked by rigid
rail portions (2b) of the second actuating means (2). Therefore a
travel pathway allowing the vehicle to continuously travel across
the switch along the electric cable means provided on at least one
of n parallel rail means (6) defining the travel pathway B is not
provided in the setup shown in FIG. 1.
[0054] A plan projection of the specific embodiment shown in FIG. 1
is shown in FIG. 2. In this figure, the rail system is set up to
allow for a vehicle to convey a pallet along the travel pathway B.
Travel pathway A is not amenable to conveying a pallet, since the
joining points (3) and continuation points (4a) are not linked by
the rigid rail portions (1a) of the first actuating means (1).
Furthermore, the rail ends optionally holding cable ends at the
crossing portions (5a) are not linked by rigid rail portions (2a)
of the second actuating means (2). Therefore a travel pathway
allowing the vehicle to continuously travel across the switch along
the electric cable means provided on at least one of n parallel
rail means (6) defining the travel pathway A is not provided in the
setup shown in FIG. 2.
[0055] An orthographic projection of the specific embodiment of
FIG. 1 is shown in FIG. 3. In this figure, the rail system is set
up such that selectively positioning the rigid rail portions (1a)
of the first actuating means (1) so as to link the joining points
(3) and the continuation points (4a) would provide a travel pathway
A allowing the vehicle to continuously travel across the switch
along the electric cable means provided on at least one of n
parallel rail means (6) defining said travel pathway.
Alternatively, selective positioning of the rigid rail portions
(2b) of the second actuating means (2) so as to link the rail ends
optionally holding cable ends at the crossing portions (5b) would
provide a travel pathway B allowing the vehicle to continuously
travel across the switch along the electric cable means provided on
at least one of n parallel rail means (6) defining said travel
pathway.
[0056] The present invention also provides a process for operating
a switch of a rail system for a powered pallet conveyor according
to the invention. The process comprises the steps of
[0057] (a) selecting one of n alternative pathways;
[0058] (b) positioning n rigid rail portions for bridging the
distance between [0059] (i) n joining points where the m
alternative travel paths subject to switching coincide, and [0060]
(ii) n continuation points of the selected travel path downstream
from the joining points,
[0061] (c) positioning n-1 rigid rail portions for bridging the
distance between rail ends optionally holding cable ends at
crossing portions where each alternative pathway subject to
switching is discontinued downstream from the corresponding
continuation points.
[0062] Each step in the process of operating a switch of a rail
system for a powered pallet conveyor may be performed either
manually by a human controller and/or automatically by an automated
controller such as a PLC, respectively. Each step in the process
may be timed to coincide with the steps of many other identical
processes in order to maximize the overall efficiency with respect
to time or cost of conveying multiple pallets along a pathway
comprised of multiple travel pathways. An example of such a pathway
is that of a powered pallet conveyor used in sorting and
distributing pallets in, for example, line shaft production.
Accordingly, the rail system of the present invention is suitable
for use in the automobile, food, agricultural, pharmaceutical,
electronic, chemical or print industries.
[0063] Selecting one of n alternative pathways is performed prior
to the vehicle traveling across the switch, depending on the
direction in which the pallet, and hence vehicle, need be conveyed.
Selection of a pathway may be made by the controller depending on,
for example, the type of load which the vehicle and/or pallet is
carrying.
[0064] Subsequent to selecting one of n alternative pathways the
controller establishes whether the rail system is set up such that
a vehicle can cross the switch and travel along the chosen pathway.
In the event that the vehicle can cross the switch and travel along
the selected pathway, repositioning of the rail system is
unnecessary and the rail system remains unchanged. In the event
that the rail system is set up such that a vehicle cannot cross the
switch and, therefore, is unable to travel along the selected
pathway, repositioning of the rigid rail portions of either or both
of the first and second actuating means is required. The
repositioning of the rigid rail portions of the first actuating
means may be performed independently of the repositioning of the
rigid rail portions of the second actuating means.
[0065] Repositioning of the rigid rail portions of the first
actuating means is effected by the controller sending an electronic
signal to the mechanism driving the actuating means. The mechanism
repositions the first actuating means so as to ensure that a subset
of n of the (m*n) rigid rail portions bridge the distance between n
joining points and a subset of n of the (m*n) continuation points
which are located on the parallel rail means of the selected travel
pathway. This allows the vehicle to subsequently cross the switch
and travel along the selected pathway.
[0066] Repositioning of the rigid rail portions of the second
actuating means is effected by the controller sending an electronic
signal to the mechanism driving the actuating means. The mechanism
repositions the first actuating means so as to ensure that a subset
of (n-1) of the [m(n-1)] rigid rail portions bridge the distance
between the rail ends optionally holding cable ends at a subset of
2(n-1) of the rail ends at the crossing portions and thereby allow
the vehicle to cross the switch and travel along the selected
pathway.
[0067] The spatial relationship between the joining points,
continuation points and crossing points is described as follows.
The joining points are defined by the locations where the m
alternative travel paths subject to switching coincide or diverge.
The continuation points are located downstream from the joining
points along the selected travel path. Specifically, the
continuation points are located on the first actuating means at
positions distant from the n joining points along each of the
alternative travel pathways subject to switching. Furthermore, the
crossing points are located at positions distant from the rigid
rail portions of the first actuating means along each of the
alternative travel pathways subject to switching.
[0068] The process for operating the switch of the rail system
thereby provides the selected pathway allowing the vehicle to
travel along an electric cable means provided along at least one of
n parallel rail means defining the selected pathway.
* * * * *