CA2045557A1 - Automatic goods transport device with transport elements driven by a linear motor - Google Patents
Automatic goods transport device with transport elements driven by a linear motorInfo
- Publication number
- CA2045557A1 CA2045557A1 CA002045557A CA2045557A CA2045557A1 CA 2045557 A1 CA2045557 A1 CA 2045557A1 CA 002045557 A CA002045557 A CA 002045557A CA 2045557 A CA2045557 A CA 2045557A CA 2045557 A1 CA2045557 A1 CA 2045557A1
- Authority
- CA
- Canada
- Prior art keywords
- stator
- transport elements
- accordance
- sensors
- transport
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
- H02K41/02—Linear motors; Sectional motors
- H02K41/03—Synchronous motors; Motors moving step by step; Reluctance motors
- H02K41/031—Synchronous motors; Motors moving step by step; Reluctance motors of the permanent magnet type
-
- 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
- B65G54/00—Non-mechanical conveyors not otherwise provided for
- B65G54/02—Non-mechanical conveyors not otherwise provided for electrostatic, electric, or magnetic
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Control Of Linear Motors (AREA)
- Linear Motors (AREA)
- Non-Mechanical Conveyors (AREA)
Abstract
Abstract A device for transporting goods, in particular in production plants, with transport elements which move along at least one path of motion and with a linear motor drive device for driving the transport elements, which has a bank of stator poles on the path of motion and a bank of permanent magnets on the transport elements, characterized by probes which detect the presence of a transport element located in a given position relative to the position of the probe, arranged on the path of motion; power converters with coils which supply current to the stator coil; and an electronic control which, on the basis of signals from the probes, switches the power converter on and off at the appropriate moment and with the appropriate sign, maintains distances of the transport elements during their motion, and stops the transport elements when precisely positioned.
Description
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The invention relates to a device for transporting products, in particular in factories, with transport elements which are movabla along at least one path of movement, with a linear motor drive device ~or the driven movement o~ the transport elements, which has stator poles with coils along the path of movement, with sensors disposed on the path of movsment, which respond when a transport element is located at a set relative position in respect to the sensor location, with power converters, from which current can be supplied to the coils of the stator poles, and with an electronic control which switches the power converters on and off at the correct times and with the correct sign on the basis of signals of the sensors.
In connection with such transport devices, which are particularly embodied for an automatic sequence of functions, the goal is not only to move transport elements with the aicl of a linear motor, but it is also intended that the electronic control takes over the job of controlling the traffic on the path cf movement. As a rule, it is necessary that the transport elements are stopped at set stations, for example for taking on products or of unloading products.
A device for transporting products is known from German Published, Non-Examined Patent Application DE-OS 37 02 248, in which three types of co:ils for the stator poles are provided. There are primary coils for stopping, primary coils for braking, and primary coils for intermediate acceleration. The use o~ different types of coils is expensive. It is necessary in particular to pay attention to the correct use of the ~espectively required coils in the course of assembly. ~he known device is embodied as a magnetic suspension system, where the drive takes place via secondary conductors on the transport element. Such a secondary conductor is formed by a connecting plate made o~
aluminum steel, which is divided into several parts.
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5~57 In the known device, it is the job of the electronic control to control the power converters on the basis of sensor signals; however, it is first necessary to select the appropriate coils (stopping coils, braking coils, acceleration coils) before the actual control operation of the current in the coils takes place.
In agreement with the preamble of claim 1, a device for transporting products is described in European Patent Disclosure EP-A-0 294 731, where a continuous longitudinal stator is eguipped with sensors disposed at even distances. This known arrangement is used as a transport device in a production line and has the purpose o~
moving workpieces to set work stations. The workpieces on the transport elements must be arranged in exact positions at the work stations for treatment. For this, it is stated in the reference that the linear motor is embodied for the exact positioning of the transport elements (carriers of workpieces).
On a production line, it is not only important that the individual transport elements are exactly positioned but particulary that the movement of the individual transport elements is regulated. Among other things, it is necessary to prevent one transport element from colliding with a previous or stopped transport element.
It is not stated in the reference how such traffic control could be basically designed.
It is the obiect of the invention to recite a device of the species cited above, which is of simplP
construction and where the electronic control regulates the traffic on the path safely and without great effort.
This object is attained in accordance with the characterizing part of claim 1 in that a plurality of stator poles is combined in a stator pole group, the coils of which are connected, preferably in series, to a common power converter, that a plurality of stator pole groups forms a ' ' 20~555~ :
stator section, that ~t least one sensor is assign~d to each stator section, and that the electronic control maintains the distances between the transport elements in the course of their movement on the basis of signals from the sensors~
The simple construction is a result, among other things, of the use of the same coils for all operational functions. "Traffic control", i.e. in particular maintenance of set distances between individual transport elements, is attained by the division of the transport path into individual stator sections, where each stator section comprises a plurality of stator pole groups In this way, it is possible to control the transport element exactly within the stator section and furthermore the maintenance of a safe distance from one section to the other section takes place.
By means of the design in accordance with the invention of the device, a product transport device for factories is provided which for all practical purposes has the same construction from one section to the other.
Control also is correspondingly simple. Additionally, there is the possibility of lengthening the path of movement for the transport elements without difficulties. For all practical purposes, it is possible to establish "stations"
at any arbitrary point along the path of movement without the need of taking any additional steps. In connection with the known praduct transport line, it is necessary to equip the individual stations with special component~, for example, special sensors and magnet arrangements are required at each station in addition to the stopping coils.
If it is desired to displace an arbitrary station by some distance along the path of movement, it is necessary to perform considerable assembly work in connection with the known device. This effort is not necessary because of the embodiment of the device in accordance with the invention.
The universal coils are used for performing all operational ' ' ! ' . , ; . , . . . .
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functions of the transport elements, in particular their acceleration, movement at a set speed, deceleration and stopping at an exact position.
Other transport systems are known from the prior art. US Letters Patent US-PS 3 787 716 shows a product transport lien in which the runners of the transport elements are equipped with special pole sensors.
European Patent Disclosure EP-A-272 897 shows a transport line with stationary disposed sensors. German Published, Non-Examined Patent Application DE-OS 34 02 143 shows a transport line with a linear motor drive, where sensors are disposed along the line for controlling the speed of the individual transport elements.
It is possible in principle to employ a single type of sensor disposed along the path of movement. ~he signals provided by these sensors make it possible for the electronic control to provide for the switching on and off of the power converters at the correct times and with the correct sign, monitoring of the distanre between the transport elements as well as the exact positioning o~ the transport elements as they are stopped. However, it is preferred and o~ten technically mor~ advantageous for the ~ ~;
embodiment of the electronic control to provide a plurality of specialized types of sensors, in particular movement sensors which provide signals for switching the power converters on and off at the correct time, proximity sensors providing signals for control ~f the distance between the moving elements, and position sensors providing signals for the exactly positioned stopping of the moving elements.
Altogether sensors are preferred which respond to the magnetic fields o~ magnets on the transport elements. A
typical example are Hall sensors. The sensors can respond to the permanent magnets of the linear motor drives which are provided anyway on the transport elements. It is also possible to provide separate permanent magnets on the ~ . ' ' . ,' ~ ; ~
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, ~ 5 transport elements, to which the (various) sensors respond.
It is furthermore possible to provide different types of actuation means to which different sensors respond and which are part of the state of the art, such as mirrors and optical sensors, or the like.
If, in a preferred manner, numerical agreement between the coils of the statox poles and/or the power converters is provided, a reserve capacity is created, on the basis of which the operational function of the entire device is maintained at the designed drive capacity, even in case of failure of individual coils, groups of coils, power converters or the like.
The invention and embodiments of the invention will be described in detail by means of exemplary embodiments shown in the drawings, in which Figure 1 is a section of a transport device illustrating a linear motor drive device for transport elements and the basic mode of operation of an electronic control therefor;
Figure 2 is a brief section of the linear motor drive device of Figure 1 in an enlarged scale to illustrate the technical layout; and Figure 3 is a detailed further exemplary embodiment of an electronic control for a transport device.
A transport element 2 is schematically shown in Figure 1, which can be moved along a path 4 of movement, for example the floor of a factory building. A row of permanent magnets 6 with alternating polarity and constant spacing 8, extending along the transport element 2, is fastened to the underside of the transport element 2. A concrete example would be approximately 30 to 50 permanent magnets 6 and a length of the row of permanent magnets of 3 to 5 m.
A plurality of stator elements 10 is arranged one behind the other along the path of movement, buried in the floor 4 of the building or above it~ Each one of the stator : ~ ,: . " :
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elements lO contains in the longitudinal direction of the path of movement a plurality of stator poles 12 and coils 14 (see Figure 2). A concrete example would consist of approximately 8 to 12 stator poles 12 per stator element 10 and a length of 0.8 to 1.2 m of the stator elements 10.
Within each stator element 10 there is the same pole spacing 8 as in the row of permanent magnets. At the point ~f transition between each stator element 10 and the respectively adjacent stator element, the pole spacing is somewhat greater than inside the stator element 10. The stator poles 12 belonging to one stator element 10 are designated as a stator pole group, and the coils 14 belonging to a stator element lO are designated as a coil group. `
Wheels 16 are disposed at the bottom of the transport element and roll along the floor 4 of the building in order to maintain th~ permanent magnets 6 at a distance from the stator elements lO. The air gap, measured : :
vertically between the lower pole surfaces of the permanent magnets 6 and the upper pole surfaces of the stator elements 10, is designated by 18. The permanent magnets 6 consist Df an Sm-Co material or of an Fe-Nd material or of a ferrite material. Such permanent magnet materials have a magnetic -conductivity approximately that of air, preferably a magnetic permeability of 1 to 2, so that small deviations of the air gap 18 from the design air gap width, for example because of deviations in the floor 4 of the building from an exactly straight level or because of compression of the tires of the wheels 16, or the like, do not hav~ any noticeable effect on the drive output o~ the linear motor drive device. The width of the air gap 18 is approximately 1 0 mm .
A power converter 20 is provided for each stator element 10 and provides power briefly and in temporally alternating directions of current to each of the coils 14, ' ': ' ' ' ' '' " ': ', '.; ' ' ' ' ' : . ' .. . . . . . . . . . .
switched in series~ o~ the respective stator elemQnts 20.
Because o~ the series connection of the coils 14, the intensity of current flowing through the associated power converter 20 is less than if the coils 14 were connected in parallel.
The six power converters 20 illustrated are connected in parallel to a common power supply. The power supply has a supply rectifier 22, a choke 24 as well as a capacitor 26 for smoothing, and a switching supply element 28. The switching supply element 28 provides one or a plurality of auxiliary voltages, which are lower than the power supply voltages and are required by the power converters 20. The area between the power supply and the power converters 20 is designated as the direct voltage intermediate circuit 30.
Together, the six stator elements 10 illustrated comprise a stator section 32. A Hall sensor 34, which responds to the magnetic fields of the permanent magnsts 6 of thP transport element 2, is assigned on the path 4 of movement to each stator element 10 of this stator section 32. The signals of the sensors 34 provide the basis for the electronic control of the linear motor drive device 36. Tha electronic control has an electronic motor control unit 38 which controls the switching on and off of the power converters 20 at the correct times and with the correct sign on the basis o~ the signals of the sensors 34. A
microprocessor control unit 40 providing additional control functions, which will be explained below, is superordinated to the motor control units 38 of a plurality o~ circuit sections 32. A memory-programmable control 42 is superordinated to the microprocessor control unit 40. An operating unit 44 is connected to the memory-programmable control 42.
The linear motor section 32 comprising six stator elements 10, the motor control unit 38 with the associated ' ' ' ' ' : :1 "
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sensors 34, the six power converters 20 and, if reguired, the associated power supply, together form a power unit. A
plurality of such power units are connected to the microprocessor control unit 40 and the memory-programmable control 42, so that the entir~ linear motor drive device 36 is ~ormed in this manner.
The signals o~ the sensors 34 can also form the basis for the control of the desired distances between the individual transport elements 2 on the path 4 of movement.
An example of this is the possibility of control where the microprocessor control unit 40 only permits the activation oP the stator section 32 after the respective transport element 2 has left the respective stator section 32. The sensor 34 can also provide the basis for stopping the respective transport element 2 at an exact position, for example by interrupting the power supply when passing the last permanent magnet 6 or by trigyering a braking device, for example when passing the tenth permanent magnet of the transport element 2. "Distance control" and "braking control" can be assigned to the microprocessor control unit 40.
Further discernible in Figure 1 are a brake chopper 46, csnnected to the direct: voltage intermediate circuit 30, and one or a plurality of braking resistors 48 ~
25 switched downstream thereof. The energy released during --slowiny or braking of the respective transport element 2 is eliminated via the brake chopper 46 in the braking resistor 48. A return feed into the power supply is alternately possible, in which case the supply rectifier 22 would be embodied as a two-way rectifier.
Because of the offset between the stator elements 10, which is different from the permanent magnet spacing 8, ths individual power converters 20 are switched on and off temporally oPfset on the basis of the temporally offset signals of the sensors 34. AltPrnately, it is possible in ~55~7 g principle that only one sensor 34 per stator section 32 would suffice, because the speed of the transport elements ensues fr~m the frequency of the signals of the sensor 34 and the required temporal offset can be calculated, for example, in the motor control unit 38 or in the microprocessor control unit 40.
In the exempl~ry e~bodiment shown in Figure 1, all coils 14 of an illustrated stator element 10 are connected to a common power converter 20 and in this way form a coil 10 group connect~d in the same phase. It is alternatel~ -possible to form, in a different connection, even-phased or almost even-phased coil groups connected to a common power ~:~
converter 20. If, for example, the offset between the stator elements 10 is selected in such a way that the stator element 10 disposed at the extreme left in the central stator section 32 and the stator element 10 disposed at the extreme left in the adjoining stator section 32 have a total offset of one or two permanent magnet spacings 8 (or a multiple thereof), it is possible, for example, to connect the two foremost coils 14 of these two stator elements 10 and, if desired, also of further, analogously arranged stator elements 10, to a common power converter 20.
Analogously the same is true for the second, third, ...
coils 14 of each stator element 10. The result is stator pole groups or coils groups which are distributed in a more spread-out fa~hion along the path 4 of movement. Thus, if a power converter 20 fails, there is a less noticeable disruption of the operational function of the device.
It is furthermore pointed out that the power ~upply described need not be separately provided for every power unit described, which consists essentially of a motor control unit 38 and a number of power converters 20, although this might be pr~ferred? for example, in connection with large, installed drive outputs. It is quite possible to provide a common power supply for a plurality of stator ,` ~ ~ , , . . ,, :, i5~
~ 10 -- .
sections 32 or even for the entire linear motor drive device of the entire path 4 of movement.
It is possible to provide the described power units decentralized/ for example ess~ntially spatially asssciated with the appropriate stator section 32.
Alternately, it is possible to dispose the power units centrally together or in groups and to connect them electrically with the individual stator sections 32.
It is preferred to provide a redundant power installation, calculated on the basis of a design drive output. In the exemplary embodiment illustrated in Figure 1, in respect to the drive each transport element 2 acts simultaneously together with ~our stator elements 10. If, for example, the layout is such that three stator elemenks 10 already provide the design drive output, one of the four power converters 20 or one of the four stator elements 10 can fail, but the design drive output is still maintained.
In case of even greater demands made on operational readiness, it is possible to provide an even more powerful redundant installation.
The motor control unit 36 or the microprocessor control unit 40 contains information as to the set speed of the speed of movement of the transport elements 2. The actual speed information detected by means of the sensors 34 is continuously compared with this set speed in~ormation and th~ activation of the power converters 20 is made a function of this comparison.
Furthermore, a plurality of drive programs is stored for example in the microprocessor control unit 40 which differ, for example, as to acc~leration, deceleratiQn or speed of movement of the transport elements 2. It is possible to select one of the desired drive programs with th~ help of the memory-programmable control 42 or the operating unit 44.
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In case of failure of the power ~iupply, a switch to generator power operation of the stator elements 10 is madP by the microprocessor control unit 40. The voltage present in the direct voltage intermediate circuit 30 as a result of this isiupplies the respective switching supply element 28 and maintains, via the lines 56, the voltage supply of the motor control unit 38 and the microprocessor control unit 40 for all practical purposies until the transport element(s) 2 has come to a stop with the distance still controlled.
It can be seen in Figure 2 that only every second stator pole 12 is provided with a coil 14 or that a non-wound stator pole 12 is present ahead of and behind each stator pole provided with a coil 14. Those stator poles 12 which simultaneously are coil cores are in magnetically conducting contact with the non-wound stator poles 12.
~djoining stator elements lO are magnetically separated from each other~ The coils 14 in the form of prefabricated units are placed over the appropriate stator poles and fastened there.
Figure 3 illustrates a refined electxonic control.
Each one of the five stator sections 32 illustrated has -not expressly drawn in - six coil groups or stator elements 10. An electronic motor control Ullit 38 is assigned to each stator section 32. The motor control unit 38 is connscted to the microprocessor control unit 40 by means of a bus connection (data bus). The motor control units 38 and the microprocessor control units 40 are furthermore connected with an electronic brake demand device 52 which, in turn, is connected with the memory-programma~le control 42, the same as the microprocessor control unit 40. Each stator section 32 again has six drive sensors 34a (only thre~ being indicated in the drawing), the signals of which provide the basis for the switching on and off of the power converters at the correct times and with the correct sign.
! ; :.: ' , ' .' ~ , : ' ' ; ' ' Z~5~:;57 Corresponding to the number of the stator elements 10 containad in it, six power converters are assigned to each stator section 32, which are not separately drawn in.
Furthermore, a proximity sensor 34b is assigned to each stator section 32, the signals of which are supplied to the memory-programmable control 42 and form the basis for the triggering of a bxake when transport elements come too close to each other. Finally, a position sensor 34c is provided in each stator section 32 ~only drawn in for one stator :~
section 32), the signals of which are supplied to the appropriate motor control unit 38. Based on the signals of :
the positioning sensor 34c and in co-operation with the electronic brake demand device 52, it is possible to stop a transport element 2 correctly in the exact posi~ion. It is furthermore possible to provide a ~ine adjustment for the last stretch of the path of movement around the point of positioning. The positioning sensor 34c preferably does not respond to the permanent magnets 6, but to a separate :-positioning magnet 54, which is indicated in Figure 1.
The control functions which are a part of the associated area of the manufacturing location are concentrated in the memory-programmable control 42, for example reactions to disruptions i:n the delivery of products to the transport device, change to a differ~nt series of products or the like.
The path of movement of the transport device may be a closed loop or open, with a starting point and an end.
Curved paths of movement can also be handled without problems. It is understood that, if necessary, the transport elements can be laterally guided, for example magnekically by means of a linear motor drive device, by lateral guide wheels or in that the whaels 16 described run in groove-shaped recesses. For example, it is po~sible that the transport elements 2 in all five ~tiator sections 32 simultaneously and synchronously roll into the exact stop .. .. ... . . . . . . . . . ........... .. . . .......... ... . .
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position, even i~ the individual transport elements 2 carry different product types and dif~erent conditions of resistance to movement obtain.
As a rule the layout i~ such that at least a distance o~ the length of one stator el~m~nt 10 is provided between the individual transport elements 2, so that at any moment considered each stator element 10 co-operates with at most one transport element 2.
The invention relates to a device for transporting products, in particular in factories, with transport elements which are movabla along at least one path of movement, with a linear motor drive device ~or the driven movement o~ the transport elements, which has stator poles with coils along the path of movement, with sensors disposed on the path of movsment, which respond when a transport element is located at a set relative position in respect to the sensor location, with power converters, from which current can be supplied to the coils of the stator poles, and with an electronic control which switches the power converters on and off at the correct times and with the correct sign on the basis of signals of the sensors.
In connection with such transport devices, which are particularly embodied for an automatic sequence of functions, the goal is not only to move transport elements with the aicl of a linear motor, but it is also intended that the electronic control takes over the job of controlling the traffic on the path cf movement. As a rule, it is necessary that the transport elements are stopped at set stations, for example for taking on products or of unloading products.
A device for transporting products is known from German Published, Non-Examined Patent Application DE-OS 37 02 248, in which three types of co:ils for the stator poles are provided. There are primary coils for stopping, primary coils for braking, and primary coils for intermediate acceleration. The use o~ different types of coils is expensive. It is necessary in particular to pay attention to the correct use of the ~espectively required coils in the course of assembly. ~he known device is embodied as a magnetic suspension system, where the drive takes place via secondary conductors on the transport element. Such a secondary conductor is formed by a connecting plate made o~
aluminum steel, which is divided into several parts.
..
. , , . , . :
,. , ,. . ; ,: ~ :,: i . : ,: :~ , :~
.. . , ~. -. :~ ~ . ..
,: , , , .: . . .~.,.. , ,: .
5~57 In the known device, it is the job of the electronic control to control the power converters on the basis of sensor signals; however, it is first necessary to select the appropriate coils (stopping coils, braking coils, acceleration coils) before the actual control operation of the current in the coils takes place.
In agreement with the preamble of claim 1, a device for transporting products is described in European Patent Disclosure EP-A-0 294 731, where a continuous longitudinal stator is eguipped with sensors disposed at even distances. This known arrangement is used as a transport device in a production line and has the purpose o~
moving workpieces to set work stations. The workpieces on the transport elements must be arranged in exact positions at the work stations for treatment. For this, it is stated in the reference that the linear motor is embodied for the exact positioning of the transport elements (carriers of workpieces).
On a production line, it is not only important that the individual transport elements are exactly positioned but particulary that the movement of the individual transport elements is regulated. Among other things, it is necessary to prevent one transport element from colliding with a previous or stopped transport element.
It is not stated in the reference how such traffic control could be basically designed.
It is the obiect of the invention to recite a device of the species cited above, which is of simplP
construction and where the electronic control regulates the traffic on the path safely and without great effort.
This object is attained in accordance with the characterizing part of claim 1 in that a plurality of stator poles is combined in a stator pole group, the coils of which are connected, preferably in series, to a common power converter, that a plurality of stator pole groups forms a ' ' 20~555~ :
stator section, that ~t least one sensor is assign~d to each stator section, and that the electronic control maintains the distances between the transport elements in the course of their movement on the basis of signals from the sensors~
The simple construction is a result, among other things, of the use of the same coils for all operational functions. "Traffic control", i.e. in particular maintenance of set distances between individual transport elements, is attained by the division of the transport path into individual stator sections, where each stator section comprises a plurality of stator pole groups In this way, it is possible to control the transport element exactly within the stator section and furthermore the maintenance of a safe distance from one section to the other section takes place.
By means of the design in accordance with the invention of the device, a product transport device for factories is provided which for all practical purposes has the same construction from one section to the other.
Control also is correspondingly simple. Additionally, there is the possibility of lengthening the path of movement for the transport elements without difficulties. For all practical purposes, it is possible to establish "stations"
at any arbitrary point along the path of movement without the need of taking any additional steps. In connection with the known praduct transport line, it is necessary to equip the individual stations with special component~, for example, special sensors and magnet arrangements are required at each station in addition to the stopping coils.
If it is desired to displace an arbitrary station by some distance along the path of movement, it is necessary to perform considerable assembly work in connection with the known device. This effort is not necessary because of the embodiment of the device in accordance with the invention.
The universal coils are used for performing all operational ' ' ! ' . , ; . , . . . .
555~
functions of the transport elements, in particular their acceleration, movement at a set speed, deceleration and stopping at an exact position.
Other transport systems are known from the prior art. US Letters Patent US-PS 3 787 716 shows a product transport lien in which the runners of the transport elements are equipped with special pole sensors.
European Patent Disclosure EP-A-272 897 shows a transport line with stationary disposed sensors. German Published, Non-Examined Patent Application DE-OS 34 02 143 shows a transport line with a linear motor drive, where sensors are disposed along the line for controlling the speed of the individual transport elements.
It is possible in principle to employ a single type of sensor disposed along the path of movement. ~he signals provided by these sensors make it possible for the electronic control to provide for the switching on and off of the power converters at the correct times and with the correct sign, monitoring of the distanre between the transport elements as well as the exact positioning o~ the transport elements as they are stopped. However, it is preferred and o~ten technically mor~ advantageous for the ~ ~;
embodiment of the electronic control to provide a plurality of specialized types of sensors, in particular movement sensors which provide signals for switching the power converters on and off at the correct time, proximity sensors providing signals for control ~f the distance between the moving elements, and position sensors providing signals for the exactly positioned stopping of the moving elements.
Altogether sensors are preferred which respond to the magnetic fields o~ magnets on the transport elements. A
typical example are Hall sensors. The sensors can respond to the permanent magnets of the linear motor drives which are provided anyway on the transport elements. It is also possible to provide separate permanent magnets on the ~ . ' ' . ,' ~ ; ~
2~45S5~
, ~ 5 transport elements, to which the (various) sensors respond.
It is furthermore possible to provide different types of actuation means to which different sensors respond and which are part of the state of the art, such as mirrors and optical sensors, or the like.
If, in a preferred manner, numerical agreement between the coils of the statox poles and/or the power converters is provided, a reserve capacity is created, on the basis of which the operational function of the entire device is maintained at the designed drive capacity, even in case of failure of individual coils, groups of coils, power converters or the like.
The invention and embodiments of the invention will be described in detail by means of exemplary embodiments shown in the drawings, in which Figure 1 is a section of a transport device illustrating a linear motor drive device for transport elements and the basic mode of operation of an electronic control therefor;
Figure 2 is a brief section of the linear motor drive device of Figure 1 in an enlarged scale to illustrate the technical layout; and Figure 3 is a detailed further exemplary embodiment of an electronic control for a transport device.
A transport element 2 is schematically shown in Figure 1, which can be moved along a path 4 of movement, for example the floor of a factory building. A row of permanent magnets 6 with alternating polarity and constant spacing 8, extending along the transport element 2, is fastened to the underside of the transport element 2. A concrete example would be approximately 30 to 50 permanent magnets 6 and a length of the row of permanent magnets of 3 to 5 m.
A plurality of stator elements 10 is arranged one behind the other along the path of movement, buried in the floor 4 of the building or above it~ Each one of the stator : ~ ,: . " :
. . . .
:' 2~5~S~
,- .
elements lO contains in the longitudinal direction of the path of movement a plurality of stator poles 12 and coils 14 (see Figure 2). A concrete example would consist of approximately 8 to 12 stator poles 12 per stator element 10 and a length of 0.8 to 1.2 m of the stator elements 10.
Within each stator element 10 there is the same pole spacing 8 as in the row of permanent magnets. At the point ~f transition between each stator element 10 and the respectively adjacent stator element, the pole spacing is somewhat greater than inside the stator element 10. The stator poles 12 belonging to one stator element 10 are designated as a stator pole group, and the coils 14 belonging to a stator element lO are designated as a coil group. `
Wheels 16 are disposed at the bottom of the transport element and roll along the floor 4 of the building in order to maintain th~ permanent magnets 6 at a distance from the stator elements lO. The air gap, measured : :
vertically between the lower pole surfaces of the permanent magnets 6 and the upper pole surfaces of the stator elements 10, is designated by 18. The permanent magnets 6 consist Df an Sm-Co material or of an Fe-Nd material or of a ferrite material. Such permanent magnet materials have a magnetic -conductivity approximately that of air, preferably a magnetic permeability of 1 to 2, so that small deviations of the air gap 18 from the design air gap width, for example because of deviations in the floor 4 of the building from an exactly straight level or because of compression of the tires of the wheels 16, or the like, do not hav~ any noticeable effect on the drive output o~ the linear motor drive device. The width of the air gap 18 is approximately 1 0 mm .
A power converter 20 is provided for each stator element 10 and provides power briefly and in temporally alternating directions of current to each of the coils 14, ' ': ' ' ' ' '' " ': ', '.; ' ' ' ' ' : . ' .. . . . . . . . . . .
switched in series~ o~ the respective stator elemQnts 20.
Because o~ the series connection of the coils 14, the intensity of current flowing through the associated power converter 20 is less than if the coils 14 were connected in parallel.
The six power converters 20 illustrated are connected in parallel to a common power supply. The power supply has a supply rectifier 22, a choke 24 as well as a capacitor 26 for smoothing, and a switching supply element 28. The switching supply element 28 provides one or a plurality of auxiliary voltages, which are lower than the power supply voltages and are required by the power converters 20. The area between the power supply and the power converters 20 is designated as the direct voltage intermediate circuit 30.
Together, the six stator elements 10 illustrated comprise a stator section 32. A Hall sensor 34, which responds to the magnetic fields of the permanent magnsts 6 of thP transport element 2, is assigned on the path 4 of movement to each stator element 10 of this stator section 32. The signals of the sensors 34 provide the basis for the electronic control of the linear motor drive device 36. Tha electronic control has an electronic motor control unit 38 which controls the switching on and off of the power converters 20 at the correct times and with the correct sign on the basis o~ the signals of the sensors 34. A
microprocessor control unit 40 providing additional control functions, which will be explained below, is superordinated to the motor control units 38 of a plurality o~ circuit sections 32. A memory-programmable control 42 is superordinated to the microprocessor control unit 40. An operating unit 44 is connected to the memory-programmable control 42.
The linear motor section 32 comprising six stator elements 10, the motor control unit 38 with the associated ' ' ' ' ' : :1 "
' ' ' `~:' : '.
: ' ~ ' " ' ':
045S5~
sensors 34, the six power converters 20 and, if reguired, the associated power supply, together form a power unit. A
plurality of such power units are connected to the microprocessor control unit 40 and the memory-programmable control 42, so that the entir~ linear motor drive device 36 is ~ormed in this manner.
The signals o~ the sensors 34 can also form the basis for the control of the desired distances between the individual transport elements 2 on the path 4 of movement.
An example of this is the possibility of control where the microprocessor control unit 40 only permits the activation oP the stator section 32 after the respective transport element 2 has left the respective stator section 32. The sensor 34 can also provide the basis for stopping the respective transport element 2 at an exact position, for example by interrupting the power supply when passing the last permanent magnet 6 or by trigyering a braking device, for example when passing the tenth permanent magnet of the transport element 2. "Distance control" and "braking control" can be assigned to the microprocessor control unit 40.
Further discernible in Figure 1 are a brake chopper 46, csnnected to the direct: voltage intermediate circuit 30, and one or a plurality of braking resistors 48 ~
25 switched downstream thereof. The energy released during --slowiny or braking of the respective transport element 2 is eliminated via the brake chopper 46 in the braking resistor 48. A return feed into the power supply is alternately possible, in which case the supply rectifier 22 would be embodied as a two-way rectifier.
Because of the offset between the stator elements 10, which is different from the permanent magnet spacing 8, ths individual power converters 20 are switched on and off temporally oPfset on the basis of the temporally offset signals of the sensors 34. AltPrnately, it is possible in ~55~7 g principle that only one sensor 34 per stator section 32 would suffice, because the speed of the transport elements ensues fr~m the frequency of the signals of the sensor 34 and the required temporal offset can be calculated, for example, in the motor control unit 38 or in the microprocessor control unit 40.
In the exempl~ry e~bodiment shown in Figure 1, all coils 14 of an illustrated stator element 10 are connected to a common power converter 20 and in this way form a coil 10 group connect~d in the same phase. It is alternatel~ -possible to form, in a different connection, even-phased or almost even-phased coil groups connected to a common power ~:~
converter 20. If, for example, the offset between the stator elements 10 is selected in such a way that the stator element 10 disposed at the extreme left in the central stator section 32 and the stator element 10 disposed at the extreme left in the adjoining stator section 32 have a total offset of one or two permanent magnet spacings 8 (or a multiple thereof), it is possible, for example, to connect the two foremost coils 14 of these two stator elements 10 and, if desired, also of further, analogously arranged stator elements 10, to a common power converter 20.
Analogously the same is true for the second, third, ...
coils 14 of each stator element 10. The result is stator pole groups or coils groups which are distributed in a more spread-out fa~hion along the path 4 of movement. Thus, if a power converter 20 fails, there is a less noticeable disruption of the operational function of the device.
It is furthermore pointed out that the power ~upply described need not be separately provided for every power unit described, which consists essentially of a motor control unit 38 and a number of power converters 20, although this might be pr~ferred? for example, in connection with large, installed drive outputs. It is quite possible to provide a common power supply for a plurality of stator ,` ~ ~ , , . . ,, :, i5~
~ 10 -- .
sections 32 or even for the entire linear motor drive device of the entire path 4 of movement.
It is possible to provide the described power units decentralized/ for example ess~ntially spatially asssciated with the appropriate stator section 32.
Alternately, it is possible to dispose the power units centrally together or in groups and to connect them electrically with the individual stator sections 32.
It is preferred to provide a redundant power installation, calculated on the basis of a design drive output. In the exemplary embodiment illustrated in Figure 1, in respect to the drive each transport element 2 acts simultaneously together with ~our stator elements 10. If, for example, the layout is such that three stator elemenks 10 already provide the design drive output, one of the four power converters 20 or one of the four stator elements 10 can fail, but the design drive output is still maintained.
In case of even greater demands made on operational readiness, it is possible to provide an even more powerful redundant installation.
The motor control unit 36 or the microprocessor control unit 40 contains information as to the set speed of the speed of movement of the transport elements 2. The actual speed information detected by means of the sensors 34 is continuously compared with this set speed in~ormation and th~ activation of the power converters 20 is made a function of this comparison.
Furthermore, a plurality of drive programs is stored for example in the microprocessor control unit 40 which differ, for example, as to acc~leration, deceleratiQn or speed of movement of the transport elements 2. It is possible to select one of the desired drive programs with th~ help of the memory-programmable control 42 or the operating unit 44.
' . . ,: :,' ', '' ,, ':' '~ ." ', ' . . . ' ' , . , ' :'" ' ' ':.. ': :,' , ' "., ' . : , 5~5~
In case of failure of the power ~iupply, a switch to generator power operation of the stator elements 10 is madP by the microprocessor control unit 40. The voltage present in the direct voltage intermediate circuit 30 as a result of this isiupplies the respective switching supply element 28 and maintains, via the lines 56, the voltage supply of the motor control unit 38 and the microprocessor control unit 40 for all practical purposies until the transport element(s) 2 has come to a stop with the distance still controlled.
It can be seen in Figure 2 that only every second stator pole 12 is provided with a coil 14 or that a non-wound stator pole 12 is present ahead of and behind each stator pole provided with a coil 14. Those stator poles 12 which simultaneously are coil cores are in magnetically conducting contact with the non-wound stator poles 12.
~djoining stator elements lO are magnetically separated from each other~ The coils 14 in the form of prefabricated units are placed over the appropriate stator poles and fastened there.
Figure 3 illustrates a refined electxonic control.
Each one of the five stator sections 32 illustrated has -not expressly drawn in - six coil groups or stator elements 10. An electronic motor control Ullit 38 is assigned to each stator section 32. The motor control unit 38 is connscted to the microprocessor control unit 40 by means of a bus connection (data bus). The motor control units 38 and the microprocessor control units 40 are furthermore connected with an electronic brake demand device 52 which, in turn, is connected with the memory-programma~le control 42, the same as the microprocessor control unit 40. Each stator section 32 again has six drive sensors 34a (only thre~ being indicated in the drawing), the signals of which provide the basis for the switching on and off of the power converters at the correct times and with the correct sign.
! ; :.: ' , ' .' ~ , : ' ' ; ' ' Z~5~:;57 Corresponding to the number of the stator elements 10 containad in it, six power converters are assigned to each stator section 32, which are not separately drawn in.
Furthermore, a proximity sensor 34b is assigned to each stator section 32, the signals of which are supplied to the memory-programmable control 42 and form the basis for the triggering of a bxake when transport elements come too close to each other. Finally, a position sensor 34c is provided in each stator section 32 ~only drawn in for one stator :~
section 32), the signals of which are supplied to the appropriate motor control unit 38. Based on the signals of :
the positioning sensor 34c and in co-operation with the electronic brake demand device 52, it is possible to stop a transport element 2 correctly in the exact posi~ion. It is furthermore possible to provide a ~ine adjustment for the last stretch of the path of movement around the point of positioning. The positioning sensor 34c preferably does not respond to the permanent magnets 6, but to a separate :-positioning magnet 54, which is indicated in Figure 1.
The control functions which are a part of the associated area of the manufacturing location are concentrated in the memory-programmable control 42, for example reactions to disruptions i:n the delivery of products to the transport device, change to a differ~nt series of products or the like.
The path of movement of the transport device may be a closed loop or open, with a starting point and an end.
Curved paths of movement can also be handled without problems. It is understood that, if necessary, the transport elements can be laterally guided, for example magnekically by means of a linear motor drive device, by lateral guide wheels or in that the whaels 16 described run in groove-shaped recesses. For example, it is po~sible that the transport elements 2 in all five ~tiator sections 32 simultaneously and synchronously roll into the exact stop .. .. ... . . . . . . . . . ........... .. . . .......... ... . .
:,.. , , . ,.: , . .... : ~ 1:', , ; . : . . ~ .
- 13 - 2~ 5~
position, even i~ the individual transport elements 2 carry different product types and dif~erent conditions of resistance to movement obtain.
As a rule the layout i~ such that at least a distance o~ the length of one stator el~m~nt 10 is provided between the individual transport elements 2, so that at any moment considered each stator element 10 co-operates with at most one transport element 2.
Claims (15)
1. A device for transporting products, in particular in factories, with transport elements, which are movable along at least one path of movement, with a linear motor drive device for the driven movement of the transport elements, which has stator poles with coils along the path of movement, with sensors disposed on the path of movement, which respond when a transport element is located at a set relative position in respect to the sensor location, with power converters from which current can be supplied to the coils of the stator poles and with an electronic control which switches the power converters on and off at the correct times and with the correct sign on the basis of signals of the sensors, where the stator poles are arranged in a row and are equipped with a single type of coils for all operational functions, where permanent magnets are disposed on a row on the transport elements and where the electronic control stops the transport elements in an exact position, based on signals of the sensors, characterized in that a plurality of stator poles is combined in a stator pole group, the coils of which are connected, preferably in series, to a common power converter, that a plurality of stator pole groups forms a stator section, that at least one sensor is assigned to each stator section, and that the electronic control maintains the distances between the transport elements in the course of their movement on the basis of signals from the sensors.
2. A device in accordance with claim 1, characterized in that adjoining stator pole groups are offset from each other by a distance differing from the permanent magnet spacing on the transport elements, this offset from the spacing difference being provided in a portion of the adjoining stator pole groups or in all adjoining stator pole groups.
3. A device in accordance with one of claims 1 and 2, characterized in that a non-wound stator pole is provided ahead as well as behind of a stator pole equipped with a coil, which is connected with the coil core in a magnetically conducting manner.
4. A device in accordance with one of claims 1 to 3, characterized in that a plurality of power converters with a common power supply is combined into a power unit which is equipped with an electronic control unit and that one or a plurality of power units are provided for the entire path of movement.
5. A device in accordance with one of claims 1 to 4, characterized in that the air gap between the pole surfaces of the stator poles and the pole surfaces of the permanent magnets is 1 to 15 mm, preferably 8 to 12 mm.
6. A device in accordance with one of claims 1 to 5, characterized in that the permanent magnets consist of a material with a magnetic conductivity approximately that of air, so that the drive output of the linear motor drive device changes only negligibly in case of changes by several millimetres of the air gap between the pole surfaces of the stator poles and the pole surfaces of the permanent magnets.
7. A device in accordance with one of claims 1 to 6, characterized in that separate proximity sensors supplying signals for the distance control of the transport elements are provided on the path of movement in addition to drive sensors providing signals for switching the power converters on and off at the correct time and with the correct sign.
8. A device in accordance with one of claims 1 to 7, characterized in that separate positioning sensors supplying signals for the stopping of the transport elements in the exact position are provided on the path of movement in addition to drive sensors providing signals for switching the power converters on and off at the correct time and with the correct sign.
9. A device in accordance with claim 8, characterized in that separate magnets or other means of influencing are provided on the transport elements, to which the drive sensors and/or the proximity sensors and/or the positioning sensors respond.
10. A device in accordance with one of claims 1 to 9, characterized by a layout in such a way that stopping of the transport elements with a positioning accuracy of less than 1 mm is possible.
11. A device in accordance with one of claims 1 to 10, characterized in that a numerically redundant installation is provided in connection with the coils of the stator poles and/or the power converters in such a way that operation with a design drive output is possible in case a few coils and/or power converters fail.
12. A device in accordance with one of claims 1 to 11, characterized in that the electronic control is laid out in such a way that the power converter control units regulate the current for the connected power converters on the basis of set speed information and of actual speed information determined from sensor signals.
13. A device in accordance with one of claims 1 to 12, characterized in that the electronic control has a memory for selectable drive programs.
14. A device in accordance with one of claims 1 to 13, characterized in that the electronic control is laid out in such a way that the electrical energy generated in the course of deceleration of the drive elements is returned to the power supply and/or is supplied to braking resistors.
15. A device in accordance with one of claims 1 to 14, characterized in that the electronic control is laid out in such a way that in case of failure of the power supply, the energy available from the deceleration of the drive elements is utilized for supplying the electronic control.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3900511.9 | 1989-01-10 | ||
| DE3900511A DE3900511A1 (en) | 1989-01-10 | 1989-01-10 | AUTOMATIC GOODS TRANSPORT DEVICE WITH LINEAR MOTOR DRIVE TRANSPORT ELEMENTS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2045557A1 true CA2045557A1 (en) | 1990-07-11 |
Family
ID=6371810
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002045557A Abandoned CA2045557A1 (en) | 1989-01-10 | 1990-01-09 | Automatic goods transport device with transport elements driven by a linear motor |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0452375B1 (en) |
| CA (1) | CA2045557A1 (en) |
| DE (2) | DE3900511A1 (en) |
| WO (1) | WO1990008086A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019075193A1 (en) * | 2017-10-11 | 2019-04-18 | Velocity Magnetics, Inc. | Using linear synchronous motors for retarding linear motion and conveying systems |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2736176B2 (en) * | 1991-02-14 | 1998-04-02 | 株式会社東芝 | Control device for linear motor driven elevator |
| DE4305274A1 (en) * | 1993-02-20 | 1994-09-01 | Krauss Maffei Ag | Long stator (elongated stator, longitudinal stator) linear motor |
| WO1996027544A1 (en) * | 1995-03-06 | 1996-09-12 | Sig Schweizerische Industrie-Gesellschaft | Device for conveying products between different work stations |
| DE19512523A1 (en) * | 1995-04-03 | 1996-10-10 | Daimler Benz Ag | Track-guided transport system for goods conveying |
| JP3370678B2 (en) * | 1995-04-03 | 2003-01-27 | ダイムラークライスラー アクチエンゲゼルシャフト | Truck-guided conveyor with energy and information transfer |
| DE19733547C2 (en) * | 1997-08-02 | 2003-12-18 | Noell Crane Sys Gmbh | Control and position detection of conveyor systems with linear synchronous motor drive |
| TNSN00089A1 (en) * | 1999-04-26 | 2002-05-30 | Int Paper Co | MULTIPLE JAW SEALER |
| DE10025351A1 (en) * | 2000-05-23 | 2001-11-29 | Wittenstein Gmbh & Co Kg | Lift / swivel drive |
| DE10256203A1 (en) * | 2002-11-30 | 2004-06-09 | Stefan Eickenberg | Points for a transport system for slide carriages uses permanent magnet on slide carriage to interact with electromagnet underneath to produce force to accelerate slide carriage transversely to transport direction |
| DE102004027905A1 (en) * | 2004-06-09 | 2005-12-29 | Leybold Optics Gmbh | Conveying device for transporting substrates on a coating production line has carrier, drive and stabilizer modules with moving heads and acceleration devices |
| DE102004037622A1 (en) * | 2004-08-02 | 2006-02-23 | Leybold Optics Gmbh | Process system and device for transporting substrates |
| DE102005013349A1 (en) * | 2005-03-23 | 2006-10-05 | Bosch Rexroth Aktiengesellschaft | Linear motor and method for operating a linear motor |
| EP2182628A1 (en) | 2008-10-31 | 2010-05-05 | Robert Bosch GmbH | Method and apparatus for controlling a linear motion system |
| EP2182621B1 (en) | 2008-10-31 | 2012-06-06 | Robert Bosch GmbH | Method and apparatus for controlling a linear motion system |
| EP2182627B1 (en) | 2008-10-31 | 2012-02-01 | Robert Bosch GmbH | Method and apparatus for controlling a linear motion system |
| GB2485759B (en) * | 2010-10-15 | 2015-08-26 | Baa Ip Holdco Ltd | Transport |
| EP2746201B1 (en) * | 2012-12-21 | 2015-09-30 | Robert Bosch Gmbh | Apparatus and method for conveying carriers in a machine |
| DE102012025326B4 (en) * | 2012-12-22 | 2022-01-20 | Festo Se & Co. Kg | Method for operating an electromagnetic transport system and electromagnetic transport system |
| US10889449B2 (en) | 2017-09-25 | 2021-01-12 | Canon Kabushiki Kaisha | Transport system and manufacturing method of article |
| CN113541435B (en) * | 2021-06-29 | 2022-09-06 | 中国科学院电工研究所 | Distributed linear motor propulsion system and power supply method |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3787716A (en) * | 1972-02-16 | 1974-01-22 | Aerospace Corp | Linear pulsed d.c. motor and controls therefor |
| JPS59138523A (en) * | 1983-01-25 | 1984-08-09 | Hitachi Kiden Kogyo Ltd | Transfer control method for article to be conveyed by linear motor |
| DE3414312A1 (en) * | 1984-04-16 | 1985-10-24 | Magnet-Motor Gesellschaft für magnetmotorische Technik mbH, 8130 Starnberg | ELECTRICALLY CONTROLLED ELECTRIC MOTOR |
| GB2185720B (en) * | 1986-01-27 | 1989-11-01 | Daifuku Kk | Conveyor system utilizing linear motor |
| JP2501808B2 (en) * | 1986-12-19 | 1996-05-29 | 株式会社東芝 | Magnetic levitation transfer system |
| DE3722524A1 (en) * | 1987-06-06 | 1988-12-22 | Krause Johann A Maschf | PRODUCTION ROADS AND METHOD FOR THE PRODUCTION OF WORKPIECES ON THE SAME |
-
1989
- 1989-01-10 DE DE3900511A patent/DE3900511A1/en not_active Ceased
-
1990
- 1990-01-09 DE DE9090901571T patent/DE59000699D1/en not_active Expired - Fee Related
- 1990-01-09 CA CA002045557A patent/CA2045557A1/en not_active Abandoned
- 1990-01-09 WO PCT/EP1990/000043 patent/WO1990008086A1/en active IP Right Grant
- 1990-01-09 EP EP90901571A patent/EP0452375B1/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019075193A1 (en) * | 2017-10-11 | 2019-04-18 | Velocity Magnetics, Inc. | Using linear synchronous motors for retarding linear motion and conveying systems |
| US11496075B2 (en) | 2017-10-11 | 2022-11-08 | Velocity Magnetics, Inc. | Using linear synchronous motors for retarding linear motion and conveying systems |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990008086A1 (en) | 1990-07-26 |
| DE3900511A1 (en) | 1990-07-12 |
| EP0452375B1 (en) | 1992-12-30 |
| DE59000699D1 (en) | 1993-02-11 |
| EP0452375A1 (en) | 1991-10-23 |
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