Railways – Monorail
Reexamination Certificate
2000-10-16
2002-07-16
Le, Mark T. (Department: 3617)
Railways
Monorail
C104S119000, C104S120000, C104S243000, C104S245000, C104S288000, C105S030000, C191S014000
Reexamination Certificate
active
06418855
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to an industrial truck which is designed, in particular, for use in a production line and can be moved by means of a drive, the movement direction of the truck being determined by a guide element.
Industrial trucks of the type mentioned serve for interlinking individual production stations and are imperative, in particular, in automated production systems. In this case, the driving takes place externally by means of a cable or chain pull which is positioned in the underlying surface of the production installation and is arranged such that it can be moved in a slot-like guide element. The industrial truck, which runs on wheels, is connected to the drive by a drawing means which extends into the slot-like guide element. In this case, the cable or chain pull is mostly designed to circulate. Following a full cycle, the industrial truck is disengaged or transferred to a further conveying means. The disadvantage with an industrial truck of the type mentioned is that the guide element has to be positioned in a sunken manner in the underlying surface or the entire production installation has to be arranged in an elevated manner on a platform, in order reliably to eliminate any risk of injury and obstruction of the production process. This involves considerable outlay, and, in addition, flexible adaptation to a different production sequence is only possible with an unreasonably high level of outlay, if at all.
It is also disadvantageous that the individual industrial trucks can only be moved synchronously by the common drive, with result that it is necessary to keep to a standard cycle time. Removal of an individual industrial truck for reworking or in the event of malfunctioning is only possible at diverters or removal stations provided specifically for this purpose. In addition, malfunctioning of the drive affects all the industrial trucks connected up, with result that it is always a number of stations or an entire production line that is affected by the malfunctioning. In addition to the associated risk during failure of the installation, this also produces, at the same time, considerable outlay in terms of the production control.
Furthermore, the drive of such an industrial truck is comparatively susceptible to malfunctioning since particles of dirt accumulate in the depression in the underlying surface and the drive may thus be blocked.
SUMMARY OF THE INVENTION
The invention is based on the problem of configuring an industrial truck of the type mentioned in the introduction such that there is a reduction in outlay during use of such an industrial truck and in the event of changes to the route and, at the same time, there is an increase in the operational reliability.
This problem is solved according to the invention in that the drive is a friction drive which is arranged on the industrial truck, on the one hand the friction drive being supported on the industrial truck and, on the other hand, the friction wheel of the friction drive rolling on the underlying surface or on an element fixed thereto. This makes it possible for a number of industrial trucks to be operated at independent speeds because each industrial truck has a separate drive. Consequently, malfunctioning of the drive merely affects a single industrial truck, with result that it is not possible to obstruct further production stations or the production line as a whole. At the same time, the design of the drive as a friction drive allows the industrial truck to be exchanged easily without a specific diverter or removal station being necessary for this purpose. Since a friction drive produces merely a limited propulsion force, the risk of individuals being involved in accidents is largely ruled out. After striking an obstruction, the industrial truck merely remains at a standstill, the friction wheel spinning, and can then also be accelerated manually in order to compensate for any time losses occurring, for example, as a result. The industrial truck can be moved on wheels or rollers but also on sliding elements.
The guide element could be a colored guide line on the ground, it being possible for said guide line to be sensed by means of optical sensors, an induction line or else a camera with a corresponding control means. On the other hand, a development of the invention in which the guide element is a rail on which the friction drive acts by way of the friction wheel is particularly advantageous. This easily makes it possible to achieve reliable guidance of the industrial truck. In this case, the friction pairing of the friction wheel and the rail may be optimally adapted to the respective use purpose, with the result that it is also possible to overcome upward or downward slopes without difficulty. For this purpose, the friction wheel can butt against the rail, for example, laterally or from above. For better guidance, the friction drive may be provided with a further friction wheel, with result that the two friction wheels butt from opposite sides against the rail or against two parallel lateral boundary surfaces. In this case, and for the purpose of avoiding injury, the rail does not have any sharp edges or protrusions and, in addition, has a conspicuous coloring.
A particularly advantageous development of the invention is provided when the friction wheel is prestressed in relation to the rail by means of an adjustable spring element. As a result, the desired propulsion can be optimally adjusted to the respective circumstances. In particular, it is thus possible to take account of alternating load states and to limit the maximum propulsion force, with result that an immediate standstill is achieved when an obstruction is struck. Furthermore, it is also possible to compensate for unevennesses of the guide element and wear-induced abrasion on the friction wheel.
Particularly expedient here is a configuration of the invention in which the rail is arranged such that it projects from the underlying surface. This makes it possible to achieve flexible adaptation of the rail routing to different production processes without specific structural changes, in particular the provision of a depression in the underlying surface, being necessary for this purpose.
A particularly expedient modification of the invention is also provided when the rail has an introduction aid for the friction wheel. This makes it possible to provide individual route sections in which the rail is interrupted and the industrial truck can thus be displaced manually as desired. Individual production stations may thus be disengaged from the cyclic operation. The friction wheel of the industrial truck can then be introduced without difficulty into the rail by means of the, for example, wedge-shaped introduction aid and engagement of the friction wheel in the rail can thus be resumed.
It is also particularly expedient if the rail has a stop element which can be actuated manually. This makes it possible for the industrial truck to stop without difficulty at a desired location in order thus to allow convenient processing of the components conveyed on the industrial truck. For this purpose, for example, it is possible to discontinue the engagement of the friction wheel in the rail or else the supply of energy to the drive. Furthermore, it is also possible to have straightforward stop elements in the case of which the industrial truck merely strikes against the stop element and increased slippage thus occurs on the friction wheel.
A particularly straightforward configuration of desired rail routing is achieved in that the rail is made up of individual elements. Elements preformed in this way may thus easily be assembled to form a desired route. By virtue of such a modular construction principle, it is easily possible to realize a different route or subsequent extensions which, depending on the route, only require a small number of fixing means, if any at all. If there is any wear or damage, the relevant elements may quickly be exchanged, with result that the production process is only limited to a slig
Farber Martin A.
Le Mark T.
Mannesmann VDO AG
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