CA1037315A - Conveyor system including an overhead rail and a number of self propelled driving units - Google Patents

Abstract

A B S T R A C T

A conveyor system comprising an overhead rail and a num-ber of self-propelled driving units, movable along the rail for moving associated load carriers such as floor supported carts along the path of the rail by means of a pulling rod connection between the driving units and the load carriers, wherein the pulling rod holding means of each driving unit are operatively connected with means for urging the driving wheel or wheels of the unit against the rail for increasing the frictional driving engagement therebetween in response to an increased rearward pull in the pulling rod. The verti-cal component of the pulling force is applied to the driving wheel through a force moment amplifying arrangement, and the horizontal component of the pulling - or pushing - force is applied to the driving wheel through a force direction con-verter arrangement.

Description

~1373~5 The present inv~ntion relates to a con~eyor system of the type comprising an overhead guiding rail supporting a number of driving units each provided with a driving motor so as to be movable along the rail with means for holding one end of a depending pulling rod operable to be connected with a load carrier for driving the carrier along the path of the rail, and for a driving unit for use in such a system.
Conveyor sys~ems of this type are used for driving a number of load carriers along the path of the rail in order to move goods from one position to another, e.g. in freight terminals. Normally the load carriers are floor supported carts having a handle rod which can be hooked into and out of engage-ment with the lower end of a pulling rod extending downwardly from each driving member. However, in some systems the pulling rod hangs down from the driving units so as to carry a hanging load. The self propelled driving units include an elec~ric motor energized through a contact rail arrangement. This motor operates under varying load conditions, from driving its associated driv-ing unit idly to pulling a heavily loaded carrier and even pulling it along an upwardly inclined path.
The mo~or and the driving wheel arrangement, of course, should be designed so as to be operative at maximum load conditions, this involving a irm frictional engagement between the driving wheel and the rail. Preferably the driving units should be as light as possible, so normally the weight of the driving unit is not sufficient to provide the necessary firm engagement. Con-ven*ionally, therefore, the driving units are provided with counter pressure wheels, and a spring arrangement is interposed between these wheels and the driving wheels so as to urge the driving wheel against the rail with increased force for providing the necessary friction there~etween. However, the fric-tional engagement thus being permanently adapted to maximum load conditions, this will involve a mechanical construction which is in fact amply dimensioned, since maximum loaded conditions are normally encountered only sporadically.
Also the friction between the driving unit and the rail will be kept at a con-stantly high level.

-2-B

1~373~
It is the purpose of this invention to provide a driving unit and a conveyor system of the ~ype referred to in which th~ describ~d disadvantages arecounteracted or eliminat~d.
According to the invention t~ere is provided a self propelled driving unit for a conveyor system wherein, in ope:ration, self-propelled driving units run along an overhead traction rail to transport loads either slung beneath or towed by the driving units; said driving unit comprising a wheeled carriage adapted to run along the rail and having wheels adapted to roll agains~ opposed surfaces o~ the rail~ one of the carriage wheels constituting a traction wheel for driving the carriage by frictional engagement with the rail and being coupled with a prime mover to be rotated thereby~ and one of the carriage wheels being mounted on a lever arm which is pivotally connec~ed to the carriage, such as to be movable bodily relative to the carriage and mechanism serving for the attachment of a load to the driving unit, said mechanism being coupled with said lever arm and being operative to transmit the pull of the load to the lever arm to urge said wheels, against the rail thereby to produce a contact pressure between the traction wheel of the carriage and the rail which is depen-dent upon the magni~ude of the load, and said mechanism including means to transmit to the lever arm components of said pull directed both normal to and parallel to said rail.
It will be appreciated that in such a system the actual force of engagement between the wheels and the rail will automatically adjust itself so as to be low when no very firm frictional engagement is required and high only when required, as determined by the pull or drag acting on the driving unit through the pulling rod. Springs or other permanent sources of high clamping forces can be entirely avoided so as to enable a simple construction of the driving unit.
In the following the invention is described in more detail with refer-ence to the accompanying drawing, in which:-Figure 1 is a side view of a portion of a conveyor system according to the invention, Figure 2 is a perspec~ive view of a driving unit and the rail means,

-3-:~373~5 Figure 3 is a cross sectional v~ew thereof, Figure 4 is a more detailed side v:lew o~ the dr~vlng ~mlt?
Figure 5 is a corresponding view o:~ a modified embodiment of the driving unit, and Figure 6 i5 a view corresponding to Figure 5, but showing the drlving unit assuming an incllned positlon.
The system illustrated in Figures 1-4 comprises a rail 2 mounted under the ceiling and serving to support a number of driving units 4 each provided with a depending pulling rod 6 the lower end of which is connectable to the outer end of a handle rod 8 of a load carrier cart 10 adapted to roll along the floor. The pulling rods 6 are normally spring loaded so as to swlng upwardly when they are not actually ,: .: .'"~.'' 3~ :

~ . ~
~L037~5 coupled together with a handle rod 8~ The rail 2 is made o~
profiled plate material which is self carrying between su-spensiQn brackets secured to the ceiling. In the embodiment shown the plate rail 2 is generally of inverted U cross sect-ion, and the lower side portions thereo are profiled so as to ha~e inwardly protruding box flanges 10 each having a top side 12 and a bottom side 14. Preferably the rail side port-ions are extended further downwardly at 16 and provided with inwardly protruding bottom flanges 180 The interior vertical surfaces of the box flanges 10 are designated 20a The flange top sides 12 constitute the surfaces on which the driving units are rollingly supported~ as described in more detail below. In operation the dri~in~ units will be practically .
~otally enclosed within the plate rail, iOe. they are to~a large degree protected from dust, and beside~ the entire rail .
system will have a very "clean" app2arance, also because the current rails for energizing the driving motors may be mount-ed inside the hollow rail, preferably underneath the ceilin~
thereof as shown at 22~ whereby the current rails are mounted -20 or placed in a highly protected manner. The rail is o~ course usable also in a complex system including rail junctions and rail switch controlled rail branchings~
~ t intervals the rail is secured to suspension brackets 24 each comprising ~ top piece 26 connected to the ceiling in any suitable manner and a pair of side pieces 28 made of flat iron bent according to the main shape of the rail sides and having a reinforcing flange 30. The flat iron 28 is secured to the plate rail side by means of bolts 32, The rail 2 holds a number of driving units of which one is shown in fiys. 1-4. It comprises an elongated base chassis _ 5 ~ ~ ~
~:~37~3~5 34 which is situated in the space betw~en the lower rail ~ide portions 16 and provided wi.th an upstanding post 36 to the upper end of which ther~ is pivotally secured one end of an elongated upper chassis portion 38~ the other end of which is pivotally secured to a vertical lever 40 to be described in more detail below. On the upper chassis portion 38 is mount~d a gear box 42 associated with an electric driving motor 4a and having a crosswise arranged dri~ing sha~t 46 provided with a driving wheel 48 at either end thereo~ These .
opposed driving wheels and therewith the entire driving unit . ~ . ~ , . .
are carried on the respëctive opposed top side portions o the box ~langes 10 wi~h whic~~they are in ~rictional driving engagement~ ~ ~~~
The base chassis 34 is provided with two upstanding rol-- lers 50 generally or almost filling out the cross sectional space ~etween the opposed slde wall portions 20 of the box flanges 10 so as to act as guiding rollers guiding the driv-ing unit longitudinally along the railO Moreover, the base chassis 34 is provided with laterally arrang~d rollers 52 projecting under the bottom surfaces 14 of the box flanges 10 and rollingly enga~ing these surfaces so as to constitute counter pressure wheeIs for the driving wheels 48.
The lever 40 extends ~rom the upper chassis 38 downwardly ~hrough a recess 54 in the Iower chassis, and at its lower end it is connected to a bracket 56 to which the top end o~
the pulling rod 6 is pivotally secured. Preferably a hinge 58 ls interposed~between the elements 40 and 56 in order to . .
allow ~or a limited transverse pivotin~ of the bracket 56~

On the upper chassis may be mounted a control box shown in dotted lines at 60 and serving to house various control ele-':

d~
93~3:15 ments and circuits such as destination code responsive motor switch meansJ which7 however, shall need no further descript-ion in the pr~sent connection. The box 60 may be provided with upper sliding shoes 62 (see fig~ 3) engaging the current rails 64 and with a control signa1 transmitter and receiver unit which is moved along a control rail 66 with which it communi-cates in any convenient manner in order to be able to r~ceive start/stop signals and to transmit eOgO rail switch actuating signals for automatic operation.
The weight distribution about th~ transverse line of engagement between the driving wheels 48 and the rail surface portions 1~ is such that the upper chassis 38 tends to tilt abo~t this line so as to lit the post 36 and therewith the entire lower chassis 7~ whereby the counter pressure wheels 52 engage the rail surface portions 14 with an up~ard pressure, which is only small as long as the driving unit is unloadedO
~en the pulling rod 6 is engaged to a cart and the driving unit is started the pull transferred to the lever 40 will serve to increase the force with which the post 36 and therewith the wheels 52 are urged upwardly, or correspondingly the force with which the driving wheels 4~ are urged downwardly, whereby the frictional engagement between the wheels 48 and the rail will increase~ .
The pulling direction being inclined, only the vextical component of the pull will be active for producing the sai~
increas~ of the pressure of the driving wheels against the railO As shown in fig. 4, however, the driving unit is pro-vided with means for converting the horizontal component of the pull into a downwardly directed force on the lever 40, these means comprising a pin or roller 68 mounted on a side ' i!"^
~373~5 portion of the lever 40 and a block element 70 secured to the lower chassis 34 inside the rocess 54 so as to have its inir~lined front end 72 situated ~ust above the pin or roller :~, It will be understood that the ~orizontal component of a counter traction pull in the pulling rod 6 will cause the pin or roller 68 to be urged horizontally against the inclined cam surface 72 of the block 70, whereby the lever 40 will be urged correspondingly downwardly and thus contribute substan-tially to th~ desired increase of the said frictional driving engagement in response to the pulling *orce being increased.
As shown in ~ig. 4 another block member 74 is mounted i~ front of the pin or roller 68 so as to have an inclined cam surface portion 76 situated just abo~e the pin or roller 68 opposite to the cam portion 720 This arrangement shows the important effect that the lever 40 will be drawn downwardly also in response to a push being transferred through the pulling~rod such as can be actual by a sudden stop~of the driving unit or when the cart is moved along a downwardly sloping floor portionO In these cases the motor 44 will act as a positive braking device when the driving wheels 48 do not slide along the rall, and the increased wheel friction caused by the pin or roller 68 engaging the cam sur~ace 76 will thus secure a good braking effect~
Fig. 5 shows a modified embodiment in which the means ~or converting a horizontal pull or push in the lever 40 into a vertical force are inverted of those shown in figO 4, viz~
comprising a cam member 68' mounted on the lever 40 and a pair of pin~ or rollers 72' and 76' mounted in the recess 54.
The embodiment of figO 5 is used in fig. 6 for showing that the invention is applicable also to conveyor systems in - 8 ~

, ~1~37~3~
which the driving units are ~dapted to con~ey hanglng loads, In such systems, of course, there are no problems. as to the ~rictional driving engagement during movement in the horizontal direction, but the problems occur should the driving unit move along upwardly or downwardly sloping rail sections, As illustrated in Figure 6, however, tKe pull exerted by a load hanging in the rod 6 will cause the lever 40 to be subjected to a pulling force component parallel to the moving direction of the driving unit, whereby an increased frictional driving engagement will be automatically obtained in the same manner as described in connection with Figures 4 and 5, Correspondingly the frictional braking engagement will be increased when the driving unit moves through a downwardly sloping path.
The invention is not limited to the embodiments shown, since it will be obvious that many modifications will be possible within the scope of the invention in order to obtain the self adjusting clamping force between the driving wheels and the rail, Thus, the driving wheels and the counter pres-sure wheels should be urged away from each other if they are arranged so as to engage with interfacing surface portions of the rail, It will be understood that in the embodiments of Figures 1 - 5 the desired amplification of the frictional engagement between the driving wheel and the rail in response to an increased pull in the pulling rod is obtainable already by virtue of the vertical force component in the member 40, since the horizontal distance between the member 40 and the post 36 is larger than the distance between the engagement point of the driving wheel 48 and the post 36.
A very high force amplification will be obtained if the wheel 48 is mounted very close to the post 36, but in practice this arrangement requires that the thickness of the rail should be extremely uniform throughout the length there-of, as otherwise the upper chassis 38 and therewith the member 4 and the rod 6 would oscillate violently up and down, Placing the driving wheel 48 a greater distance from the post 36 involves a reduced force amplification, but this reduction is compensated for by means of the particular force converter arrangement enabling also the hori~ontal force component to contribute to the clamping force, and then the almost inevitable thickness variations of the _ 9 Y

C

.

~L03~3:~LS
rail become less criticall The said converter arrangèment, of course, is especially important for causlng a braking action in case of a push being transferred to the member 40 through the pulling rod 6, ,. , :,''.

', "'` '",:'' ~` 10 ~
'

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A self propelled driving unit for a conveyor system wherein, in operation, self-propelled driving units run along an overhead traction rail to transport loads either slung beneath or towed by the driving units;
said driving unit comprising a wheeled carriage adapted to run along the rail and having wheels adapted to roll against opposed surfaces of the rail, one of the carriage wheels constituting a traction wheel for driving the carriage by frictional engagement with the rail and being coupled with a prime mover to be rotated thereby, and one of the carriage wheels being mounted on a lever arm which is pivotally connected to the carriage such as to be movable bodily relative to the carriage and mechanism serving for the attachment of a load to the driving unit, said mechanism being coupled with said lever arm and being operative to transmit the pull of the load to the lever arm to urge said wheels against the rail thereby to produce a contact pressure between the traction wheel of the carriage and the rail which is dependent upon the magnitude of the load, and said mechanism including means to transmit to the lever arm components of said pull directed both normal to and parallel to said rail.

2. A driving unit as claimed in claim 1 wherein said mechanism includes a coupling link pivotally connected to the lever arm and having thereon means associated with a cooperating means on the carriage whereby, irrespective of the direction of the pull of the load on the driving unit, the resultant force transmitted through the coupling link to the lever arm will be such as to urge the wheel on the lever arm against the rail.

3. A driving unit as claimed in claim 2 wherein the wheel mounted on the lever arm is the traction wheel for driving the carriage.

4. A driving unit as claimed in claim 2 wherein said means on the coup-ling link and said cooperating means on the carriage comprises a force-direction converting mechanism adapted to convert the component of the pull of the load parallel to the rail into a force component acting on the lever arm substantially normal to the rail.

5. A driving unit as claimed in claim 4 wherein said force-direction converting mechanism includes an abutment member and a surface against which said abutment member bears under the action of the pull of the load so as to develop in said coupling link a reaction force directed substantially normal to said rail.

6. A driving unit as claimed in claim 5 wherein said coupling link is arranged so as to extend through an opening in the carriage, and said abut-ment member and bearing surface are provided respectively on the coupling link and on the carriage in the region of said opening, or vice versa.

7. A driving unit as claimed in claim 5 or 6 wherein said abutment member comprises a roller and said bearing surface is a cam surface,

8. A conveyor system comprising one or more driving units as claimed in claim 1 and a traction rail along which said driving units are arranged to propel themselves.

9. A conveyor system as claimed in claim 8 wherein said traction rail has an inverted substantially U-shaped cross-section with the driving units adapted to run along inwardly projecting portions of downwardly extending limbs of the inverted U.

10. A conveyor system as claimed in claim 9 wherein said inwardly pro-jecting portions are constituted by box flanges formed in the rail, upper and lower surfaces of said box flanges defining said opposed surfaces.

11. A conveyor system as claimed in claim 10 wherein said driving units have guiding rollers arranged to run along generally vertically disposed surfaces of said box flanges.

12. A conveyor system as claimed in claim 9, 10 or 11, wherein a partition is provided in the inverted U-shaped rail so as to divide the interior of the rail into upper and lower portions, one on either side of said partition, said driving units being arranged to run along the rail substantially within said lower portion thereof, electrical supply lines being secured to said partition to be contacted by sliding contacts on the driving units for supplying tractive power thereto, and said upper portion serving as a housing for conduits or the like.