Electricity: motive power systems – Plural – diverse or diversely controlled electric motors – Work and feed motors
Reexamination Certificate
1999-12-21
2002-01-29
Ip, Paul (Department: 2837)
Electricity: motive power systems
Plural, diverse or diversely controlled electric motors
Work and feed motors
C318S098000, C318S099000, C198S330000, C198S321000
Reexamination Certificate
active
06342768
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
NOT APPLICABLE
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
NOT APPLICABLE
REFERENCE TO A “MICROFICHE APPENDIX”
NOT APPLICABLE
BACKGROUND OF THE INVENTION
This invention relates to a displacement apparatus arranged for guiding a carrying device along at least two rails. Such a displacement apparatus is known from European patent application 0,394,201.
This known displacement apparatus comprises a first and a second rail, arranged above each other in one plane, while on each rail a running gear is arranged which carry a carrying device. Each running gear comprises a toothed wheel engaging a tooth track on the rail in question. This displacement apparatus comprises a motor providing for the drive of the carrying device, with the position of the carrying device, at least in inclined portions of the rails, being determined by the toothed wheels and the motor. The upper rail, at least in horizontal portions, is provided with a stability rail which is guided between two pairs of stability wheels, which stability wheels are fixedly connected with the carrying device. It is thus provided that upon a load off the center of the carrying device, as seen in front view, the carrying device is yet held in the desired vertical position.
This known displacement apparatus involves the disadvantage that it is particularly costly in manufacture and use, while moreover there is a substantial risk of malfunctions, in particular in that the displacement apparatus, in the horizontal portions of the rails is statically overdetermined.
The cause of this is that in order to obtain the desired stability, the guide rail and the guide wheels must be positioned particularly accurately to obtain a proper cooperation. In itself this is already costly and time-consuming, but even if a high degree of accuracy is given, the risk exists that unacceptably great forces on the guide wheels and the guide rail arise, partly as a consequence of relative displacements of the displacement apparatus relative to the rails, other than in the intended direction of displacement. Moreover, the mechanical loading of guide rail and guide wheels, in particular upon initial engagement, is often too high. As a result, often breakage in the guide wheels and/or the guide rail will occur, or the carrying device will jam, while moreover a high degree of wear will arise. A further disadvantage associated therewith is that the manufacture, installation and maintenance of such a known displacement apparatus are to be carried out particularly accurately, which is costly and leads to a high susceptibility to failure.
Further, international patent publication WO 92/14673 discloses a displacement apparatus of the type described in the opening paragraph hereof, in which a running gear is arranged on two rails arranged above each other in one plane, for carrying a carrying device. Each running gear comprises a drivable wheel, while the drives of the two wheels are mutually coupled through a coupling shaft. Via one motor, therefore, during use, both the upper and the lower driving wheel are controlled, with the drives, accordingly, being synchronized. This means that in particular in inclined portions of the rails, the position of the carrying device is determined by both the shape of the rails and the toothing provided thereon, and by the drive. This gives rise to a statically overdetermined construction which requires a particularly accurate manufacture and setting of the different parts of the displacement apparatus. This displacement apparatus too, therefore, is costly in manufacture and maintenance, and moreover susceptible to failure. In particular, this is also because upon asymmetrical loading of the carrying device, at least to the extent that a moment relative to the running gears arises, an unequal loading of the two driving wheels is obtained, so that an increased wear will arise and moreover the disadvantages mentioned are enhanced still further. Moreover, there is the risk that a driving wheel moves relative to the other driving wheel, giving rise to chronic skew.
Further, EP 0,152,136 discloses a displacement apparatus of the type described in the opening paragraph hereof, in which the two rails are mutually connected by connecting parts and are of hollow design. Through the rails and the connecting parts extends an endless bead chain. On each rail a running gear is provided, mutually connected by a carrying device. The upper rail is open at the underside, such that the upper running gear, by way of a driving cam, can engage between the beads of the chain. Adjacent the lower end of the upper rail, a driving wheel is arranged with which the bead chain can be moved, thereby driving the carrying device through the driving cam. Each running gear comprises two sets of wheels engaging the same rail at spaced apart points, the sets of wheels running on the upper and the lower rails being mutually coupled through a four-bar mechanism, such that positional changes occur synchronously. This known displacement apparatus is complex in construction and control and is susceptible to wear, in particular the bead chain and the driving cam, while the displacement apparatus is moreover statically overdetermined, owing to the four coupled sets of wheels.
The known displacement apparatuses are suitable for use both with horizontal displacements and with displacements proceeding along an inclined path.
BRIEF SUMMARY OF THE INVENTION
A displacement apparatus according to the invention is provided which includes a first rail, and a second rail extending substantially parallel thereto, while on the first rail a first driving gear with a first motor is provided and on the second rail a second driving gear with a second motor is provided, the first and the second rail comprising at least one inclined part, and control means being provided for the two motors, which control means are arranged for controlling the first and the second motor in a force-controlled manner at least on a portion of the at least one inclined part of the first and the second rail.
The use of two motors, one on each rail, which can be controlled in a position-controlled manner or force-controlled manner, as desired, provides the advantage that the carrying device, both with horizontal and with inclined rails, can be held in a desired position at all times, without the construction being statically overdetermined. At all times, on each portion of the rails, a suitable control can be chosen. Additionally, the advantage is achieved that any positional errors of the running wheels on the running rails can be simply compensated. Further, such a displacement apparatus has the advantage that the same assembly of a carrying device and driving gears can be used for both horizontal rails and vertical rails, and for a combination thereof, without entailing the disadvantages mentioned.
In further elaboration, a displacement apparatus according to the invention is provided having at least one substantially horizontally extending part of the first and second rail, the control means being arranged for controlling the first and second motor in a position-controlled manner at least on a portion of the at least one substantially horizontal part of the rails.
The use of position-controlled motors on rails extending horizontally, at least inclining to a very minor extent only, provides the advantage that a carrying device can be simply held in a desired position by means of the driving gears, regardless of the loading of the carrying device, while the rails and driving gears can be manufactured with relatively large tolerances. Force-controlled drive of the motors on inclined parts of the rails then provides the advantage that the construction is not statically overdetermined, and on the inclined parts is automatically held in the desired position.
In the case of force-controlled drive, each motor will be controlled depending on the forces applied to the driving gear, which forces are directly dependent on the loading of the carrying device. He
Ip Paul
Merchant & Gould P.C.
Thyssen de Reus B.V.
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