Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61B—RAILWAY SYSTEMS; EQUIPMENT THEREFOR NOT OTHERWISE PROVIDED FOR
  • B61B13/00—Other railway systems
  • B61B13/12—Systems with propulsion devices between or alongside the rails, e.g. pneumatic systems
  • B61B13/125—Systems with propulsion devices between or alongside the rails, e.g. pneumatic systems the propulsion device being a rotating shaft or the like
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G35/00—Mechanical conveyors not otherwise provided for
  • B65G35/06—Mechanical conveyors not otherwise provided for comprising a load-carrier moving along a path, e.g. a closed path, and adapted to be engaged by any one of a series of traction elements spaced along the path
  • B65G35/063—Mechanical conveyors not otherwise provided for comprising a load-carrier moving along a path, e.g. a closed path, and adapted to be engaged by any one of a series of traction elements spaced along the path the traction element being a rotating bar or tube

Definitions

• the present invention relates to an overhead conveyor system comprising a rail, a rotatable drive shaft extending along the rail and located above the rail, and at least one carriage, which is adapted to run along the rail and to support a load suspended from the carriage, which carriage is provided with at least one drive wheel, which is inclined relative to the longitudinal di- rection of the drive shaft and spring-loaded against the drive shaft .
• WOOO/34161 discloses overhead conveyor systems of the kind stated above, which are convenient for overhead transport of heavy loads. However, in some situations, such as in the case of upward gradients along the transport track, occasional slippage between the drive wheel and the drive shaft has been observed, which results in excessive wear and necessitates premature replacing of the drive wheel .
• An object of the present invention is to solve the above problems and provide satisfactory propulsion of carriages also in the case of upward gradients along the track.
• a system of the kind stated above further comprising a spring means for pressing the drive wheel against the drive shaft by spring load, which spring means has a first spring constant during an initial depression of the drive wheel, and a second spring constant upon depression of the drive wheel a specific distance, and wherein a distance between a circumferential surface of the drive shaft and the rail is reduced along segments of the rail in which additional driving force is required, so that along said segments the drive wheel is depressed more than said distance.
• This design allows a spring action with a higher spring constant along selected segments, for example along segments with an upward gradient, which allows increased driving force to be derived.
• the stepwise variable spring action can be achieved by means of a first, long helical spring and a second, short helical spring, which are adapted to press the drive wheel towards the drive shaft by spring load.
• first, long helical spring and a second, short helical spring which are adapted to press the drive wheel towards the drive shaft by spring load.
• first, initial depression of the drive wheel only the long spring will be compressed, against the action of a first spring force corresponding to the spring constant of said long spring.
• the second, short spring will be compressed, against the action of a further spring force.
• the total spring force increases in steps in a certain point, which corresponds to a stepwise spring constant increase.
• the first and the second springs may be concentrically arranged inside each other. This reduces the amount of space required as well as the need to modify existing carriages.
• the inner spring which by virtue of its smaller diameter has a higher spring constant, is shorter and the outer spring longer.
• the distance between the rail and the circumferen- tial surface of the drive shaft can be varied in different ways, for example by varying the radius of the drive . shaft along said segments, or by arranging the rail closer to the drive shaft along said segments than along the other portions of the rail .
• Fig. 1 is a perspective view of an embodiment of the overhead conveyor system according to the invention.
• Fig. 2 is a front view of a carriage belonging to the overhead conveyor system in Fig. 1.
• Fig. 3 shows part of the rail and the drive shaft in Fig. 1 according to a first alternative.
• Fig. 4 shows part of the rail and the drive shaft in Fig. 1 according to a second alternative.
• Fig. 1 illustrates an overhead conveyor system 1 of the type disclosed in WO00/34161, in which the carriages are provided with drive means according to the invention.
• the overhead conveyor system shown comprises a rail 2 which consists of two parallel rail elements 3, each rail element consisting of a hollow section of rectangular cross-section.
• the rail 2 is fixed by means of yokes 4 which are arranged spaced from each other on the outsides of the rail elements and which also are respon- sible for suspension of the overhead conveyor system 1.
• Above the rail 2 and extending along the same extends a rotatable drive shaft 5, which is drivable with the aid of means (not shown) adapted thereto, such as a belt connected to an electric motor.
• a plurality of carriages 7 are movable along the rail 2. The carriages 7 are positioned between the rail 2 and the drive shaft 5.
• the carriages 7 shown consist of a carriage body 8 with four wheels 9 and a guide means 10 (see Fig. 2) adapted to keep the carriage on the rail 2.
• a drive unit 11 is arranged consisting of at least one drive wheel 12, which is inclined relative to the longitudinal direction of the drive shaft and which by spring action is pressed towards the drive shaft .
• the carriages shown in Fig. 1 have four drive wheels
• All wheels are rotatable in suitably parallel planes, i.e. all drive wheels 12 are preferably inclined relative to the drive shaft at the same angle. It goes without saying that the number of drive wheels 12 on each carriage may vary and can be, for example, two or even one.
• the dimension of the drive unit 11 and the distance between the rail and the drive shaft are such that when the carriage is positioned under the drive shaft 5, the drive wheels 12 are brought into contact with the circum- ferential surface of the drive shaft 5.
• the carriage is propulsed along the rail.
• the drive shaft may have portions 5a, 5b of varying radius, so that the propulsion of the carriages is interrupted when it is located under small-radius portions 5b.
• Fig. 2 is a detailed front view (or rear view) of a carriage 7.
• the drive wheels 12 are adapted to be pressed towards the drive shaft by a spring means 14, which may be mounted on the carriage body 8.
• the drive wheels may for practical reasons be mounted on a cradle
• the spring means 14 comprises two pairs of concentrically arranged helical springs, one pair 15a, 15b of which is illustrated more clearly in Fig. 2.
• the outermost spring 15a is longer than the inner spring 15b, which means that initially only the spring 15a is compressed.
• the spring force of the spring means thus corresponds to the sum of the spring constants of the inner springs. If the depression of the drive wheels 12 is continued, in particular more than a distance L corresponding to the difference between the length of respectively the outer spring 15a and the inner spring 15b, the inner spring 15b will also be compressed. In this position, the spring force corresponds to the sum of the spring constants of all four springs.
• the distance between the rail and a circumferential surface 6 of the drive shaft varies along different seg- ments of the transport track. This may be achieved in a plurality of ways, for example as shown in Figs 3 and 4.
• spacing means 16 are arranged under the rail 2 in the yokes 4 located along the segment A for the purpose of lifting the rail 2 closer to the drive shaft 5 along this segment A.
• the radius of the drive shaft is greater along the segment A.
• the inner spring will also be compres- sed, which results in a stepwise increasing spring force.
• This increased spring force may be used to move the carriage past, for instance, upward gradients in the track.
• the spring means can be designed in various ways within the scope of the appended claims.
• the long spring may, for example, be located on the outside of the short spring, and the number of spring pairs may, of course, be varied.
• the springs do not have to be concentric but may also be arranged side by side or in any other manner. It is not even necessary to use a plurality of springs.
• one helical spring whose spring constant varies along different parts of its length may be used.
• An example of such a spring is a conical helical spring, or a helical spring with varying material thick- ness.
• the person skilled in the art may also choose to use other spring means than helical springs, for instance elastic material or spring steel .

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Carriers, Traveling Bodies, And Overhead Traveling Cranes (AREA)
• Chain Conveyers (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20286886

Family Applications (1)

Country Status (3)

Cited By (5)

Citations (3)

• 2002
  • 2002-02-07 SE SE0200351A patent/SE521330C2/sv not_active IP Right Cessation
• 2003
  • 2003-02-04 AU AU2003206308A patent/AU2003206308A1/en not_active Abandoned
  • 2003-02-04 WO PCT/SE2003/000182 patent/WO2003066481A1/en not_active Application Discontinuation

Patent Citations (3)

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