The present invention relates to a transportation system according
to the preamble of claim 1. Such a transportation system is known from GB 2319518A.
A transportation system of this type can be used, for example, for
moving vehicles within a parking garage. In this case, vehicles of this type are
driven to a central location and, from there, are moved away to a storage location,
and are transported back from the storage location to the central location or another
However, it should be understood that the transportation system according
to the invention also has other applications. Examples of these are the movement
of objects in warehouses and factories. In this case, the transportation system
may either be arranged on the floor or may be of overhead design, as is the case,
for example, in slaughterhouses.
GB 2319518 discloses a displacement device comprising an electric
or hydraulic motor for its displacement. Electric power may be supplied to the motor
by induction means such as a standard "bus-bar" or by means of an extensible "unbilical"
power supply line.
DE 4137201 (see also WO 93/10594 A) discloses a linear motor or generator.
A structure comprising wheels running in a recessed profile is shown. The wheels
are connected to a bridge shaped profile having permanent magnets direct to a coil.
The object of the present invention is to provide an inexpensive system
which requires. little outlay both to procure and to maintain and is of particularly
In a transportation system as described above, this object is achieved
with the characterising features of claim 1.
By using an electric linear actuator which is realised in the manner
described above, it is possible to provide a particularly robust system which can
be of relatively simple design.
According to an advantageous embodiment of the invention, the laminated
plate assembly of the coils of the moving part comprises an elongate assembly, which
extends in a first plane, designed for the coils to fit around, and at least three
laminated plate assemblies which extend in a second plane, are each arranged adjacent
to a coil and comprise a pole end, said second plane being substantially perpendicular
to said first plane.
According to this variant, it is possible to produce the coil independently
of the laminated plate assembly. As a result, it is easily possible to produce coils
with an opening on an industrial scale, and for these coils then to be pushed onto
the first laminated plate assembly. After a coil has been fitted, the second laminated
plate assembly, which extends substantially perpendicular to the first laminated
plate assembly, is fitted, after which another coil is fitted, etc. In this way,
a structure which acts as the stator of a linear actuator can be obtained particularly
quickly and efficiently.
The above process can be simplified still further if the coils are
energized with the aid of a three-phase circuit. Simple frequency converters can
be used. If appropriate, there may be a circuit which, for example, allows the moving
part to start up gradually. This moving part is preferably embodied with permanent
magnets. More particularly, permanent neodynium magnets are used. These magnets
have a particularly high coercive force. In this way, it is possible to obtain a
particularly compact structure. In recent years, the cost price of permanent magnets
of this type has fallen considerably, so that they are available even for simple
It is possible for the entire path which is to be covered by the moving
part to be provided with a stator provided with the coils described above. However,
it is also possible to arrange series of coils of this type at periodic intervals.
This is possible in particular if the length of the moving part is such that the
space between two series of coils can be spanned by the moving part. After all,
the greatest exchange of energy between moving part and stator takes place at the
start and end of a path, i.e. during acceleration and deceleration. Less kinetic
energy will be required in the intervening part.
According to a particular embodiment of a platform of this type, the
platform is of rolling design and can be locked to an actuator. This actuator then
positions the platform at the desired location, after which unlocking takes place
and the actuator is moved back. The actuator can then be used to move another platform.
The actuator may be arranged on a lift structure in order to transport the platform
from a reception area to a storage level. Moreover, there may be a structure with
further actuators, so that the platform can be moved in a direction which is perpendicular
to the first direction of displacement. In this way, it is possible to make more
effective use of the space available in a parking garage. One example of this is
to be found in Dutch Patent Application 1015963 in the name of B. Tent.
If appropriate, there may be provided Hall sensors in order to determine
the position of the moving part of the actuator with respect to the stationary part.
In principle, Hall sensors of this type are not required, since the location at
which the moving part is situated can be determined from the energy consumption
of the various coils. However, with simple frequency converters, it is possible
to connect a number of groups of coils in series/ parallel, with the result that
the precise location of the moving part is no longer certain, and, in such a situation,
sensors of this type are important in order to provide accurate control.
It will be understood that the structure described above is particularly
maintenance-free, i.e. any initial higher installation costs are amply compensated
for by the lower maintenance costs and the reduced risk of faults.
The invention will be explained in more detail below with reference
to an exemplary embodiment which is illustrated in the drawing, in which:
- Fig. 1
- shows a perspective, partially cut-away view of the stator of an actuator according
to the invention;
- Fig. 2
- shows a cross section through an actuator according to the invention;
- Fig. 3
- shows a cross section through a combination of the actuator according to the
invention and a support structure;
- Figs 4a and b
- show combinations of the structure shown in Fig. 3 and a part of a parking garage
in various positions;
- Fig. 5
- shows a plan view of a part of the structure shown in Fig. 4; and
- Fig. 6
- shows a plan view of a part of the structure shown in Fig. 4.
Fig. 1 shows the stator of a linear actuator. In the figures (Fig.
2 onwards), this linear actuator is denoted overall by 1. The stator is denoted
by 2 in the figures. It comprises a laminated plate assembly 3 extending in the
longitudinal direction. This assembly comprises a number of strips 4 which have
been placed onto one another and are preferably produced from transformer plate
with a thickness of, for example, 0.5 mm. As can be seen, the strips are in each
case provided with projections 5 and recesses 6. A number of coils 7 (3 are shown)
are present, with openings 8. Openings 8 are designed in such a manner that the
coils can be pushed over the laminated plate assembly 3 in the longitudinal direction
in a closely fitting manner. The coils are positioned at the projections 5. Laminated
plate assemblies 9 are present, comprising a number of strips 10 which are likewise
made from transformer plate and are of a suitable thickness. The opening delimited
therein corresponds to the distance between opposite recesses 6, i.e. the laminated
plate assembly 9 is enclosed in a tightly fitting manner within recesses 6, and
between two laminated plate assemblies 9 there is in each case one coil. In the
design shown here, the coils are energized using standard frequency conversion,
and the coils are connected as a three-phase circuit (RST).
According to the invention, the laminated plate assembly 9 extends
substantially perpendicular to the laminated plate assembly 3. The free ends of
the laminated plate assembly 9 form the poles. This design can be implemented particularly
easily and effectively without requiring any complicated operations. The coils may
be standard coils which are wound separately from the magnet core structure, i.e.
it is not necessary for the coils to be wound only after the laminated plate assembly
has been assembled. This allows considerable cost savings to be achieved.
Fig. 2 shows stator 2 of the actuator 1 in combination with the moving
part thereof. It can be seen from Fig. 2 that the stator is attached to a support
22 with bolts 18. Two U-rails 14 are also attached to this support 22. Wheels 15,
16 are arranged therein. The wheels 15 provide vertical positioning, and the wheels
16 provide lateral positioning. These wheels are connected to the moving part 11,
which substantially comprises a bridge frame 12. The moving part 11 has a considerable
length, perpendicular to the plane of the drawing, and comprises a succession of
permanent magnets which are arranged alternately. All this will become clear with
reference to Fig. 5. Permanent magnets 13 are arranged on this bridge frame 12.
These permanent magnets may comprise neodynium magnets. Hall sensors which can be
used to determine the position of the moving part with respect to the stator are
denoted by 17. With the aid of the structure shown here, it is possible to accurately
maintain the air gap 19 between the permanent magnets and the energized stator,
so that the optimum effect is obtained.
Fig. 3 shows how the actuator 1 can be used in combination with a
platform 29. With wheels 32, this platform rolls along beams 28 which, together
with beams 27 to which the actuator is attached, are attached to a main carriage
25 which, in turn, rolls along a main rail 26 via diagrammatically illustrated wheels
24. In main carriage 25 there are two actuators 50, as will become clear from Fig.
If appropriate, it is possible for the platform to be designed in
such a manner that any liquids originating from a vehicle, such as oil or coolant,
are collected at a central point and, with the aid of an automatically actuated
shut-off valve in a defined storage position (preferably in the central area), are
discharged to a drain arranged in the stationary part.
There may be means for damping the forces which occur when an acceleration
and/or deceleration takes place on the support plate, as may occur when vehicles
are driving on or off.
Locking arms 30 and 31 are present, by means of which the platform
29 can be connected to actuator 1. The presence of magnetizable coils 20, 33 allows
engagement to be effected. In this case, the design of the electromagnets associated
with the locking arms 30 and 31 is such that, when voltage is applied, lock 31 moves
downwards and is unlocked. The action of locking arm 30 is precisely the opposite,
i.e. locking takes place when it moves downwards. Locks 31 are used for static parking
of platform 29. Locks 30 are used for engagement with the linear actuator and moving
platform 29 when coupled to the actuator.
Fig. 4 shows a lower part of a parking garage 60. Different positions
are shown in Fig. 4a and Fig. 4b. The levels of this parking garage 60 are denoted
by 61 and 62 in Fig. 7, while the ground floor is denoted by 63. On the ground floor
there is a vehicle 64 which has been driven onto the platform 29 which has just
been described. The platform 29 is laterally delimited by auxiliary floor parts
41 which can be folded up with the aid of a jack 40, as indicated diagrammatically
in Fig. 4a. After at least one of the auxiliary floor parts has been folded up,
carriage 25 can be moved along main rail 26. This is diagrammatically illustrated
in Fig. 4b. Then, the structure comprising the main carriage 16 and what is above
it can be moved upwards to level 61 or 62 (Fig. 7). This vertical transport can
take place using a standard lift structure, although it is also possible to use
an actuator corresponding to actuator 1 for this purpose.
The presence of two actuators 50, which are spaced from one another,
in the main carriage 25 can be seen from Fig. 5. As a result, main carriage 25 can
be moved with respect to rail 26. Each actuator comprises a number of series of
coils, each series being denoted by 51. The length of the moving part of the actuator
is such that, as it passes from one series to another, a number of permanent magnets
are always acting on coils of both one series and the adjoining series. This allows
the number of coils to be limited. Naturally, it is possible to use a continuous
Fig. 6 shows a plan view of the actuator 1. This too comprises a number
of series of coils 23. Through actuation, it is possible, once platform 29 has arrived
at level 61 or 62, to be moved away from the actuator. The wheels 32 then rest on
I-sections of the relevant level. With the actuator 1, the platform 29 is moved
completely onto the relevant level, and then the actuator can be moved to a different
level with the aid of the lift in order to pick up a further platform 29 which is
optionally provided with a vehicle.
The actuators described above can be controlled using any simple frequency
controller. Expedient connection allows the number of special components to be limited
as far as possible, so that the costs of a structure of this type remain limited.
The relatively short time for which the various actuators are switched on means
that it is not necessary to use a separate cooling system, while the efficiency
of the actuators is also not of primary importance. Consequently, a simple and therefore
inexpensive structure can suffice, so that considerable economic benefits can be
achieved over conventional structures. The structure according to the invention
is in principle maintenance-free.
As indicated above, the transportation system according to the present
invention can also be used to transport other objects. The design will be adapted
accordingly. It is also possible to couple a number of platforms to one another,
in which case a single linear actuator drives a number of platforms. It is also
possible to put together a train of platforms, in which case various linear actuators
are arranged at a distance from one another. In a design of this type, the distance
between the stationary parts of the linear actuators can be selected as a function
of the expected distance between the moving parts of the actuators. Moreover, when
the movement in the starting region of the train or single actuator with platform
is relatively great, it is possible for there to be a relatively large number of
stationary parts of the linear actuators, while in a part in which constant movement
takes place there may be a smaller number, since the mass inertia means that it
is easier to span the distance between two stationary parts of the linear actuators.
It will be understood that numerous modifications may be made depending
on the use of the transportation system according to the present invention. The
way in which the displacement device is guided may be adapted according to the particular
use. Variants of this type are deemed to lie within the scope of the appended claims.