U.S. patent number 3,566,802 [Application Number 04/758,456] was granted by the patent office on 1971-03-02 for electrically controlled traction device for movable units, especially containers or shelving units.
Invention is credited to Harald O. Lundgvist.
United States Patent |
3,566,802 |
Lundgvist |
March 2, 1971 |
ELECTRICALLY CONTROLLED TRACTION DEVICE FOR MOVABLE UNITS,
ESPECIALLY CONTAINERS OR SHELVING UNITS
Abstract
A device for moving several shelving units to open a gangway
between any of them. The units are mounted on rails over a chain
and have a solenoid to operate a plunger to engage the chain. A
motor is variably coupled to the chain depending on the number of
units to be moved and switches mounted along side of the rails
control the movement of the units over specific lengths.
Inventors: |
Lundgvist; Harald O. (Geneva,
CH) |
Family
ID: |
4386612 |
Appl.
No.: |
04/758,456 |
Filed: |
September 9, 1968 |
Foreign Application Priority Data
|
|
|
|
|
Sep 12, 1967 [CH] |
|
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012814/67 |
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Current U.S.
Class: |
104/172.3;
104/178; 312/199 |
Current CPC
Class: |
A47B
53/02 (20130101) |
Current International
Class: |
A47B
53/00 (20060101); A47B 53/02 (20060101); A47b
053/02 (); B61b 013/12 () |
Field of
Search: |
;104/162,172,173
;312/199 ;104/178,76 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: LaPoint; Arthur L.
Assistant Examiner: Saifer; Robert W.
Claims
I claim:
1. A storage installation comprising a plurality of movable storage
units and means for selectively moving said units toward and away
from one another to open a gangway between selected units, said
means comprising motor drive means, flexible traction means
extending in the direction of movement of said units, slip coupling
means for coupling said flexible traction means to said motor drive
means, individual connecting means for selectively coupling
individual ones of said units firmly to said flexible traction
means in nonslipping relation thereto, each said connecting means
comprising catch means mounted on individual ones of said units and
movable between an engaged position in which said catch means is
engaged with said flexible traction means to connect the respective
unit thereto and a disengaged position out of engagement with said
flexible traction means, means biasing said catch means toward
disengaged position, electromagnetic means energizable to move said
catch means to engaged position to transmit force from said
flexible traction means to said respective unit to move said unit,
means for holding said catch means in said engaged position even
after deenergization of said electromagnetic means as long as force
is being transmitted from said flexible traction means to said
respective unit and for releasing said catch means for movement to
said disengaged position by said biasing means upon cessation of
transmission of said force when said electromagnetic means is
deenergized, and control means controlling the operation of said
motor drive and the selective actuation of said connecting means to
move one or more of said units to open a gangway between designated
storage units.
2. A storage installation according to claim 1, in which said
traction means comprises at least one link chain and in which said
catch means comprises a pin engageable in a link of said chain and
a plunger carrying said pin, said electromagnetic means when
energized moving said plunger in a lengthwise direction to engage
said pin in a link of said chain.
3. A storage installation according to claim 2, in which said
biasing means comprises spring means for moving said plunger in a
direction to disengage said pin from said chain.
4. A storage installation according to claim 3, in which said
holding means includes a cylinder in which said plunger is freely
slidable and laterally movable, and a shoulder on said plunger
engageable with an end of said sleeve to hold said plunger in
chain-engaging position when said plunger is moved laterally by the
pull of said chain on said pin.
5. A storage installation according to claim 4, in which said motor
drive means comprises means for reversing the direction of movement
of said chain, and in which said plunger is released for
disengaging movement by said spring when the direction of movement
of said chain is reversed.
6. A storage installation according to claim 1, in which said
traction means comprises a link chain and in which said catch means
is engageable with a link of said chain.
7. A storage installation according to claim 6, in which said motor
drive means comprises means for reversing the direction of movement
of said chain and in which said holding means comprises means for
retaining said catch means in chain-engaging position as long as
said chain is moving in one direction and for releasing said catch
means from said chain when the direction of movement of said chain
is reversed.
8. A storage installation according to claim 7, in which said
control means comprises means for automatically reversing said
motor drive means at the end of movement of said chain in one
direction to release said catch means.
9. A storage installation according to claim 1, in which said
traction means comprises a plurality of parallel link chains, and
in which said motor drive means comprises means for simultaneously
driving said chains in synchronism with one another.
10. A storage installation according to claim 1, in which said
motor drive means and said connecting means are electrically
operated and in which said control means comprises electric circuit
means for momentarily energizing said electromagnetic means to
connect selected units to said traction means and for concurrently
energizing said motor drive means.
11. A storage installation according to claim 10, in which said
motor drive means is reversible to drive said traction means
selectively in opposite directions, and in which said control means
comprises means for selecting the direction of movement of said
traction means depending on the location of said units with respect
to the gangway to be opened.
12. A storage installation according to claim 10, in which said
control means comprises individual switch means for each gangway to
be opened.
13. A storage installation according to claim 12, in which said
individual switch means is positioned at the location of the
respective gangway to be opened.
14. A storage installation according to claim 13, in which said
switch means comprises a single switch pedal at each gangway
location and in which said control means comprises means for
determining the direction of movement of selected units according
to the position of said units with respect to the gangway to be
opened.
15. A storage installation according to claim 14, in which said
control means comprises sectionalized contact rails and contacts
carried by individual units electrically engageable with said
rails.
16. A storage installation according to claim 10, in which said
control means comprises safety means for preventing operation of
said drive means to move selected units to close an existing
gangway when said gangway is occupied.
17. A storage installation according to claim 16, in which said
safety means comprises a pressure sensitive mat in said
gangway.
18. A storage installation, comprising a plurality of movable
storage units and means for selectively moving said units toward
and away from one another to open a gangway between selected units,
said means comprising motor drive means, flexible traction means
extending in the direction of movement of said units, sliding
coupling means for coupling said traction means to said motor drive
means, connecting means for selectively coupling individual ones of
said units firmly to said traction means in nonslipping relation
thereto and control means controlling the operation of said motor
drive and the selective actuation of said connecting means to move
one or more of said units to open a gangway between designated
storage units, said motor drive means and said connecting means
being electrically operated and said control means comprising
electric circuit means for actuating said connecting means to
connect selected units to said traction means and for concurrently
energizing said motor drive means, including individual switch
means positioned at the location of each gangway to be opened, said
motor drive means being reversible and said individual switch means
comprising two switch pedals at individual gangway locations, one
of said pedals being operable to operate said motor drive means in
one direction and the other of said pedals being operable to
operate said motor drive means in the opposite direction.
19. A storage installation, comprising a plurality of movable
storage units and means for selectively moving said units toward
and away from one another to open a gangway between selected units,
said means comprising motor drive means, flexible traction means
extending in the direction of movement of said units, sliding
coupling means for coupling said traction means to said motor drive
means, connecting means for selectively coupling individual ones of
said units firmly to said traction means in nonslipping relation
thereto and control means controlling the operation of said motor
drive and the selective actuation of said connecting means to move
one or more of said units to open a gangway between designated
storage units, said motor drive means and said connecting means
being electrically operated and said control means comprising
electric circuit means for actuating said connecting means to
connect selected units to said flexible traction means and for
concurrently energizing said motor drive means, said control means
comprising safety means for preventing operation of said drive
means to move selected units to close an existing gangway that is
occupied, said safety means comprising disconnectable electric
cables extending between adjacent units in position to be
disconnected to afford entry to a gangway between selected units,
said cables comprising part of said control means and
incapacitating said motor drive means when one of said cables is
disconnected.
Description
This invention relates to an electrically controlled traction
device for movable units, especially containers or shelving units
arranged side by side, to open a gangway between two neighboring
units, with the aid of a traction means, driven by a motor, to
which each of the units can be coupled.
With similar installations, especially when they comprise a number
of heavily loaded units, difficulties arise to design the power
transfer from the drive motor to the movable units, via the
traction means and the coupling means, so that it is sufficiently
elastic to render smooth starting of the movement possible.
In a known mechanical arrangement for moving such units, the latter
are equipped with coupling devices, which are manually operated so
that they slip on the traction means. This causes wear on the
traction means and/or the couplings as well as difficulties to
control the starting procedure without personal skill of the
operator.
In another known arrangement the units are equipped with rotating
coupling devices which are permanently engaged with the traction
means and which can be manually braked to a standstill so that the
corresponding unit is moved away by the traction means. In this
case, wear mainly occurs on the brake of the coupling device.
Personal skill of the operator is still necessary and the coupling
means required on each unit considerably increases the cost.
The object of the invention, is to provide an electrically
controlled traction device in which the motor by itself, or by
means of a slight coupling, confers to the traction means a
variable speed depending on the load carried and/or the time
elapsed.
This slip coupling provides the desired elasticity, which with
known arrangements is achieved by means of, for instance, a slip
between the traction means and the coupling device on each unit,
and this is also attained with the units connected in a slip-free
way to the traction means. The slip coupling between the motor and
the traction means replaces the expensive coupling devices on each
movable unit, and these can be equipped with the simplest
imaginable catches for the connection to the traction means.
Simultaneously with the starting of the motor, the operated unit is
coupled to the traction means. At this time the slip coupling
preferably transfers no moment of force.
Once the coupling takes place, the transferred moment of the slip
coupling increases in a preset manner from zero to a maximum value.
After a certain time, depending on the adjustment of the slip
coupling as well as the number and weight of the units to be moved,
this moment reaches a level at which the traction means is enabled
to put the units into movement. While the moment and hence the
force in the traction means further increases, the units are
accelerated to a speed of movement which corresponds to the speed
of the motor.
In practice, the units thus get started and accelerated smoothly,
independently of their weight and number, without personal
interference by the operator.
The wear problems which are caused with the known arrangements to
get elastic traction are important and are avoided by means of a
slip coupling consisting of an induction coupling with variable
magnetization current. Such couplings have no wear whatsoever. A
hydraulic coupling is suitable too, but the transferred moment is
not so easy to control automatically.
Among slip couplings with little wear, centrifugal clutches should
be mentioned. Since their transferred moment depends on the speed
of the drive shaft, they offer less possibilities to get a varying
moment over a long time than induction couplings. Finally, a
multiple-disc clutch with electromagnetic control offers about the
same control possibilities as an induction coupling, apart from the
fact that the starting moment immediately changes from zero to a
minimum value of about half the maximum moment. It further presents
noticeable wear.
By means of an appropriate electric control, the motor can be
started with a switch related to the desired gangway. If each of
the movable units has a catch for connection to one traction means
or to two synchronously running traction means, the same switch,
depending on the position of the units next to the desired gangway,
starts the motor in one or the other direction and connects one or
the other of the units to the traction means. If the movable units
can be connected to one or the other of two parts of an endless
traction means, the same switch, depending on the position of the
units next to the desired gangway, connects one or the other of
these units to the part of the endless traction means which moves
in the desired direction.
For a better understanding of the characteristic scope and feature
of this invention, reference may be made to the accompanying
drawing and following specification, in which drawing:
FIG. 1 is a vertical view of the device of this invention as
mounted on movable shelving units.
FIG. 2 is a view from above of the installation according to FIG.
1.
FIG. 3 is a view from above similar to FIG. 2 referring to an
alternative arrangement.
FIG. 4 is an enlarged fragmentary vertical sectional view along the
line IV-IV of FIG. 2 showing the coupling device mounted on
shelving unit 4.
FIG. 5 is an enlarged fragmentary vertical sectional view along the
line V-V of FIG. 4 showing the coupling device on shelving unit 4
after connection the chain 16.
FIG. 6 is a diagrammatic representation of the electrical circuit
of FIG. 1.
FIG. 7 is a view from above similar to FIG. 2 referring to another
alternative arrangement.
FIG. 8 is a vertical view similar to FIG. 2 referring to an
alternative device of this invention as mounted on a shelving
unit.
FIG. 9 is a diagrammatic representation of the electrical circuit
of FIG. 8.
The installation shown in FIG. 1 and 2 comprises a number of
movable shelving units 1--5 arranged between fixed units 6 and 7 of
which 7 has no active part in the working of the installation. The
movable units are fitted with wheels 8, which run on rails 9--12 on
the floor, so that a free space can be opened between optional
neighboring shelving units.
In the embodiment shown in FIGS. 1 and 2 the shelving units 1--5
are movable by an endless chain 16 running over a drive sprocket 15
and idler sprockets 19 and 20 in fixed unit 6 and over idler
sprockets 21 and 41 in fixed unit 7. An electric motor 13 mounted
in the fixed unit 6 driven the sprocket 15 and hence the chain 16
through a slip coupling 14 and a reducer 14a. The two parts of the
chain 16 run on top of each other guided by the idler sprockets and
by rails 17 and 18 (see FIG. 4).
The arrangement shown in FIG. 3 is like that of FIG. 2 except that
it has two parallel chains 16' and 16" driven respectively by drive
sprockets 15' and 15" and guided by idler sprockets 19', 20', 21'
and 41' and by idler sprockets 19", 20", 21" and 41" respectively.
The drive sprockets 15' and 15" of the two chains are connected
with the motor drive unit 13 (including a slip coupling and reducer
as in FIG. 2) through shafts 60' and 60" so that the drive
sprockets and the two chains 16' and 16" are driven in synchronism
with one another. The arrangement of FIG. 3 has the advantages of a
parallel drive of the shelving units and the distribution of the
load between two chains.
Under each shelving unit 1--5, one resp. two coupling devices are
fitted for connection of the shelving unit to the upper part of the
chain 16 resp. the chains 16' and 16". These coupling devices
consist of a plunger 22 actuated by an electromagnet 23 and fitted
with a pin 24 at its lower end, which may be inserted between two
links of the chain (FIG. 4). As soon as the chain 16 drives the
corresponding shelving unit, the plunger 22 is pulled somewhat
aside so that the shoulder 25 at its lower end hooks under the
lower edge 26 of the tube 27. As long as the chain 16 moves in the
same direction, the corresponding shelving unit 1--5 remains
connected to the chain 16 also when the electromagnet 23 no longer
pushes the plunge 22 down (FIG. 5).
As soon as the chain 16 is driven in the other direction, the
shoulder 25 on the plunger 22 is released from the lower edge 26 of
the tube 27 and plunger 22 returns to its initial position under
influence from the spring 28.
It will be seen that the engagement of the pin 24 in a link of the
drive chain provides a positive nonslipping connection between the
respective shelving unit and the drive chain. On the other hand,
the coupling 14 provides a sliding connection between the drive
chain and the motor 13. As described above, the coupling is
selected from the group consisting of an induction coupling with
variable magnetization control, a hydraulic coupling, a centrifugal
clutch and a multiple disc clutch with electromagnetic control.
The electric control of the motor 13 and the coupling devices is
for instance carried out in the following way:
The installation is operated by means of pedal switches 29 each of
which controls the opening of one gangway.
These pedal switches or pedals are fitted in a slanting wooden
board 30, placed in front of the installation and connected
electrically to segmented contact rails on a wooden bar 31 fixed to
the front supporting rail 12. Furthermore, all pedals are connected
to the electric control line at 24 V tension.
On the wooden bar 31 there are two series of contact rails, the
lower series 32, connected to the pedals, is segmented to establish
the length of influence for each pedal. The upper series 33, which
is also segmented, consists of parts alternately connected to one
of two lines generating impulses to start the motor in the right
and in the left direction respectively. The segmentation of this
series of rails is such that depending on the position of the
shelving unit to be driven, an impulse to start in one or the other
direction is achieved.
The segmentation of the two series of contact rails is made in
accordance with the depth of the movable shelving unit. Bar 31 may
thus be manufactured in optional length and for a specific depth of
shelving unit. (This assumes of course that all movable units in an
installation are of the same depth.) The bar is adapted to actual
gangwidth by observing that the segments of the two series of
contact rails will lie symmetrically to the two ends of the bar
(i.e. the distance from the middle between two outer segments in
the lower series to each end of the bar should be exactly equal,
and be equal to half the gangwidth minus half the depth of the
shelving unit). If the bar is thus adapted, it can be used without
changes for any gangwidth larger than half the depth of the
shelving unit, and smaller than 11/2times this depth.
The control of the solenoid 23 in the driven shelving unit is thus
achieved by means of the start impulse pedal 29 for the actual
gangway, and this is done in such a way that control tension of 24
V is led to a wire to start in a certain direction via the related
segment in the lower series of contact rails 32, a brush against
it, the solenoid 23, a brush against the upper series of contact
rails 33 and one of its segments. The electric circuit is first
maintained during a distance of movement of almost half the depth
of the shelving unit, then the brush against the upper series of
contact rails changes segment and in fact closes the circuit for
impulse to start in the other direction. Since the electric circuit
is locked, the motor 13 cannot reverse. The solenoid 23 is thus
still under tension. This state lasts a further distance of
movement of almost half the depth of a shelving unit, that is as
long as the brush against the lower series of contact rails still
lies against the segment related to the operated pedal 29. As soon
as this brush leaves this segment, the solenoid 23 has no tension
and the coupling device only remains connected to the chain due to
the hooking in as described above.
Each start impulse pedal 29 is equipped with a Reed relay - a
current relay - connected in such a way that the pedal is
short-circuited after only a short impulse through sharp pressing
of the pedal. Hence only a short impulse to start secures desired
hooking in of the coupling device.
In order to obtain the above mentioned maximum relation of 11/2
between gangwidth and depth of shelving unit, the brushes 42 have
to be fitted differently onto each shelving unit, namely one-fourth
depth of the shelving unit to the left and the right of the middle
of every second shelving unit. If all brushes were fitted equally
on all shelving units, only gangwidths up to the depth of the
shelving unit would be controlled automatically.
Thanks to the arrangement of the brushes on each shelving unit and
the division of the lower series of contact rails, the pedal
related to the desired gangway couples one or the other of the
shelving units depending on their position.
When the impulse circuit for start in a certain direction of the
motor has been closed as described above, another Reed relay
switches 220 V control tension to the contactor (G or D) for this
direction of movement. At the same time a time-limit relay 45
receives this control tension. This time-limit relay controls the
running time in the chosen direction of movement of the motor, and
has to be adjusted to different gangwidths so that a slightly
longer running time is achieved than is needed by the movement
itself. Thanks to this surplus time, the traction will manage to
absorb a possible back kick of the moved units and press them
together again.
As soon as this time has elapsed, the motor stops. Simultaneously,
however, the contactor for the motor switches a condenser 36, which
has been charged under 24 V tension during the above mentioned
running time, so that it discharges over a relay G' or D'. As a
result, the relay reverses the motor 13 while condenser 36 is
discharging. This reversing movement permits the required release
of the coupling device of the driven unit from the chain.
In the electric circuit there is a further relay 37 to switch off
the control tensions of 220 V to the contactors of the motor and of
24 V to the start impulse delivery means, if a safety device, in
the form of pressure sensitive mats 38 between the rails below the
shelving units or 43 on the kick boards of the movable units, are
short-circuited. If such mats are used on the kick boards, two
uninterrupted contact rails 39--40 are fitted on a second wooden
bar 44, against which two optionally located brushes slide.
Finally, there is a transformer and a rectifier (T). These work
continuously when the installation is ready for use and provide the
control tension of 24 V DC which is necessary because of the open
contact rails. The contact rails are not under tension when the
installation is not operated.
Thus the described installation is not provided with any flexible
electric wires to the shelving units. The operation occurs
automatically after pressing a start impulse pedal 29-- which is
located exactly in front of the desired gangway. The device
automatically chooses the shelving unit to be driven and the
direction of movement achieving the desired gangway. To facilitate
the choice of the correct pedal to obtain desired access between
two shelving units, direction lines are marked on the slanting
board 30, which point towards the opening between the two shelving
units, which will move apart after pressing the pedal. These lines
are of course influenced by the actual gangwidth and have to be
adapted to each installation.
The lines from two pedals will only meet if the gangwidth is equal
to the depth of the shelving unit, and it is then advantageous to
provide them also with arrows indicating the direction of movement.
In this special case, the operator thus has to observe the present
position of the existing gangway when choosing the adequate
pedal.
If the shelving units are numbered, the pedals may of course be
provided with corresponding double numbers instead of direction
lines so that, for instance, pedal 1--2 opens a gangway between the
shelving units 1 and 2.
An installation according to FIG. 1--7 and the above description is
thus operated by means of only a short start impulse with the pedal
29. When such an impulse has been given, the device thus achieves
in a fully automatic way the desired movement of shelving units. If
there is a person in the gangway which is to be closed, the device
cannot be started provided it is equipped with pressure sensitive
mats 38 as a safeguard. If such mats 43 are provided on the kick
boards of the movable shelving units only, the device may anyway
get started but the traction ceases as soon as any one of these
mats is touched.
Since safeguards - also in cheaper versions - considerably increase
the cost of the installation, it is desirable to try to meet
existing safety regulations in such a way that the provision of
safeguards becomes unnecessary.
According to usual safety regulations, safeguards are required when
operation occurs by impulse only, if the traction force is higher
than 150 kps and if the moved units have an energy of movement of
more than 15 kpms.
If movement only occurs as long as the pedal is pressed down and
the traction force is not more than 150 kps, no safeguards are
required if the speed of movement is limited in relation to the
total weight of the movable units, so that the energy of movement
is less than 15 kpms.
FIGS. 8 and 9 show an alternative device of this invention in which
these requirements are taken into account, so that safeguards
become optional. Furthermore, this version does not provide fully
automatic choice of direction of movement depending on the position
of the units. For each gangway position, two pedals are provided,
one for movement to the left and one for movement to the right.
Instead of the relatively complicated arrangement of contact rails
and brushes, the solenoid on each unit is directly connected by
means of a flexible cable with two adjacent pedals for different
directions of movement and related to different gangways.
FIG. 8 thus shows only the front support rail 12 and in front of
this, pedals 29' for movement to the right and 29" for movement to
the left. From a fixed point on the support rail to a fixed point
on a movable unit there is a flexible cable 46, one for each
movable unit. This cable connects the solenoid 23, which influences
the pin 24, on a movable unit with the two pedals 29' and 29"
related to the gangways on both sides of this movable unit. Due to
the flexible cable instead of the arrangement with contact rails,
the gangways can be of optional width and are not limited to
11/2times the depth of the unit at the most.
FIG. 9 shows the simplified circuit diagram provided for this
alternative device. Here the contactors G and D are replaced by
relays for 24 V control tension. Here, too, a short reversing
movement with the aid of a discharging condenser 36 over the relay
D' or G' is provided to facilitate release of the connection
between the pin and the chain, but as the installation is no longer
only operated by means of an impulse, the hooking in as described
above (FIG. 5) is unnecessary. In order to avoid undesired charging
of these condensers, diodes 47 are provided. A safeguard as shown
on FIG. 6 can of course be provided also in this alternative device
of the invention, if desired or if the traction force and/or the
energy of movement is higher than what is acceptable for
installations without safeguard.
In FIG. 8 and 9, however, an alternative safeguard is shown. In
FIG. 8 a cable 48 connects two adjacent units. This cable can for
instance be fixed by its right end on an iron plate 49 on one unit
and have a handle 50 with a permanent magnet at the other end. This
magnet is placed on an iron plate on the next unit on the left.
With all these cables placed according to the FIG. 8, an electric
connection is provided between the two fixed units 6 and 7.
If the iron plates 49 on the fixed units are connected to control
tension via a relay S as shown in FIG. 9, and if this relay
switches control tension to the solenoids 23 only when it is under
tension, the pedals 29' and 29" can only operate the installation
if the circuit between the fixed units via the movable ones is not
broken. To get access to a gangway this circuit has to be broken -
the handle end of the cable has to be removed from the iron plate -
and in this way the person in the gangway can be sure that the
installation cannot be operated and squeeze him between two
units.
The two electric controls systems described above can also of
course be used with a known version of traction of shelving units
according to FIG. 7, where the motor 13a always drives the endless
traction means 16a in the same direction. In this case each
shelving unit must be provided with two coupling devices controlled
by solenoids 23a, which are coupled to one or the other of the
parts of the traction means moving in opposite direction, so that
the driven shelving unit can be moved in the desired direction.
* * * * *