JP2006174605A - Unmanned transport truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the drop of thrust or braking force on a curve when a transport truck travels on the curve in a configuration that the thrust or braking force is given to the transport truck in a linear motor comprising a primary alternating magnetic field generating device arranged at the transport truck side and secondary permanent magnets whose surface magnetic poles NS are arranged alternately along a traveling track including the curve of the transport trucks. <P>SOLUTION: The length of the permanent magnets in the radial direction from the center of curvature on the curving traveling track 11 of the transport truck is made longer than that of the permanent magnets on a rectilinear traveling track in the direction that perpendicularly intersects the traveling direction of the transport truck according to the largeness of the curvature of the curving traveling track 11. A series of magnetic pole surfaces of the alternating magnetic field generating device 12 are configured to face the surfaces of a series of the permanent magnets over the entire surface even on the curving traveling track. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a driving device for an unmanned transport device and other transport carts that travel along a predetermined travel path including a curved portion and transport semiconductor substrates and various other transported objects between different stations.
More specifically, the present invention is an alternating magnetic field generating device that is installed on the side of the transport carriage and that travels in the traveling direction of the transport carriage, and faces the magnetic flux generation surface, and the polarity of the surface magnetic pole surface is NS alternating. It is related with the means which suppresses the fall of the thrust in the curve part of a linear motor which consists of a series of permanent magnets arrange | positioned so that it may become.

For example, in order to sequentially perform various processes (cleaning, CVD, etc.) in the semiconductor manufacturing process, in addition to a carrier for storing and transporting a semiconductor wafer, the plate-shaped body is transferred to various processing units in liquid crystal display panel manufacturing, FA, etc. From the viewpoint of improving productivity, unmanned transport devices such as Over Head Shuttle (hereinafter referred to as OHS) and Over Head Hoist Transport (hereinafter referred to as OHT) have been mainly used in recent years. It has become to.
The linear motor type driving means in OHS, OHT, etc. belonging to these unmanned conveying devices is provided on the conveying cart side, and an alternating magnetic field generating device having a predetermined length in the traveling direction of the conveying cart according to the required thrust, and this alternating magnetic field generating It is composed of permanent magnets that face a series of magnetic flux generating surfaces along the traveling direction of the transport carriage of the apparatus and whose surface polarity is alternately arranged NS along the traveling direction of the transport carriage at a predetermined interval.

By the way, in order to give a predetermined thrust to the conveyance carriage, the length of the alternating magnetic field generator as the primary side of the linear motor in the running direction in the conveyance carriage is required to be a predetermined value or more.
Therefore, when the curvature of the curved portion in the travel path of the transport carriage exceeds a certain limit, a series of magnetic poles arranged on the transport carriage side of the alternating magnetic field generator that forms the primary side of the linear motor are provided on the transport carriage side. In the surface, a portion that does not face the secondary permanent magnet disposed along the traveling path of the transport carriage is generated.

This point will be described with reference to FIG. 4 which shows an extracted main part of the prior art of the present application. In FIG. 4, reference numeral 1 denotes a travel path of a transport carriage (not shown). Reference numeral 2 denotes an alternating magnetic field generator installed on the transport cart, which extracts and displays the magnetic flux generation surface, and the travel direction (longitudinal direction) of the transport cart so as to obtain the thrust required by the transport cart. Have a predetermined length.
And the center line 2a in the advancing direction of the conveyance trolley of this alternating magnetic field generator 2 forms a straight line so as to conform to the straight line portion that occupies most of the travel path 1.
On the other hand, a surface of the permanent magnet 3 that forms a linear motor with the alternating magnetic field generator 2 and faces the magnetic flux generating magnetic pole surface of the alternating magnetic field generator 2 along the center line 1a of the traveling path 1 of the transport carriage. It arrange | positions so that a magnetic pole may become NS alternating.

Conventionally, the length of the permanent magnet 3 in the direction orthogonal to the traveling direction of the transporting carriage is basically constant except for the branching point. Therefore, when the curvature of the curved portion of the traveling path is increased, the driving of the transporting carriage is performed. Each magnetic flux generating magnetic pole surface of the primary side alternating magnetic field generation device 2 of the source linear motor has a portion that does not face the secondary permanent magnet 3 as shown in FIG.
That is, in FIG. 4, each magnetic flux generating surface for generating magnetic flux of the alternating magnetic field generating device 2 is a traveling direction of the transport carriage in the curved portion of the traveling path 1 in a region not facing the series of permanent magnets 3. It occurs at the center in the center direction and at both ends opposite to the center direction of curvature.

By the way, an alternating magnetic field generator provided on the side of the transport carriage and an array of permanent magnets facing the magnetic flux generation surface and having surface polarity NS alternately arranged along the travel path of the transport carriage, The following Patent Documents 1 and 2 exist as prior arts related to this section.
First, the technique disclosed in Patent Document 1 is for driving a conveyance vehicle 1 with a primary side alternating magnetic field generating coil 1a and a series of permanent magnets 3, 31, and 32 in which surface magnetic poles are alternately arranged NS along a traveling path. A linear motor is constituted, and in particular, the gist is to improve the branching portion of the transport vehicle 1.
Specifically, in the conventional configuration shown in FIG. 4, the series of permanent magnets 31 and 32 as the components of the linear motor are interrupted at the branch point, so that the propulsive force and the braking force in the linear direction cannot be appropriately controlled. Has improved.

As a means for this, as shown in FIG. 1, the branching section B is provided with a branching permanent magnet 4 in the form of an arc, and this permanent magnet 4 is on the traveling track before the branching section B. The permanent magnet 3, the permanent magnet 31 on the curved portion track 21 after the branching portion B, and the permanent magnet 32 on the straight portion track 22 are formed as a continuous row of permanent magnets.
As a result, it is possible to apply the propulsive force and the braking force to the transport vehicle even on the branching portion B, so that the system can be operated stably.

Further, the technique disclosed in Patent Document 2 relates to the improvement of the straight portion branch track 1 when laying the secondary side permanent magnet of the linear motor. In the conventional configuration disclosed in FIG. The main point is to improve the reduction in thrust on the arc-shaped track caused by the deviation of the axis of the track and the axis of the permanent magnet on the track side.
As shown in FIG. 1, the specific means for this is a branching / merging portion 4 of a track constituted by a linear track 21 and an arc track 11, and the surface area of the permanent magnet group 1a of the arc track is Both permanent magnet groups 1a, 1b are laid so as to be larger than the permanent magnet group 2a of the linear track.

Both Patent Documents 1 and 2 are provided with an alternating magnetic field generator on the movable side of a transport carriage or the like, and are arranged so that the surface polarity of a series of permanent magnets alternates NS along the traveling path of the transport carriage or the like. The main purpose is to prevent the reduction of the thrust of the linear motor at the branching / merging point of the conveying device.
Therefore, both Patent Documents 1 and 2 are not limited to the branch part, and it can be said that there is no direct relationship with each invention of the present application related to prevention of thrust reduction in the curved part of the transport carriage, but the thrust reduction in the curved part of the linear motor is This is disclosed as a prior art in that it is prevented or the running mode of the curved portion of the transport carriage driven by a linear motor is disclosed.

JP-A-11-168805 JP 2002-315113 A

The alternating magnetic flux generator on the primary side of a linear motor used as a driving device for a transport carriage in conventional OHS, OHT, etc., provides a predetermined thrust to the transport carriage as described above, with respect to the traveling direction of the transport carriage. Requires a certain length or more.
Therefore, among the traveling paths of the transport carriage, in particular, as the curvature of the curved portion increases, the transport carriage is against a series of permanent magnets whose polarities are alternately arranged NS on the surface along the center line of the curved travel path. A portion where the magnetic flux generating surface of the alternating magnetic field generating device installed on the side cannot be opposed to the entire surface is generated, resulting in a reduction in thrust of the transport carriage.
As a means for improving this, it is conceivable to divide the alternating magnetic field generator installed in the transport carriage into two parts using a well-known bogie mechanism. However, it is difficult to adopt from the viewpoints of structural complexity, cost, and maintenance of the alternating magnetic field generator required for this.

Accordingly, an object of the present invention is to provide an entire surface of each magnetic pole surface of a primary alternating magnetic field generator that is installed on the conveyance carriage side and linearly extends in the traveling direction in the configuration of the conveyance carriage driving linear motor such as OHS, OHT, etc. Is capable of facing the secondary side permanent magnet and does not reduce the thrust on the transport carriage even on the curved traveling path.
The specific means for realizing this is that the length of the permanent magnet forming the linear motor secondary side in the direction perpendicular to the traveling direction of the conveying carriage is set in the linear traveling section according to the curvature of the curved traveling path of the conveying carriage. Compared to longer times.
Details in this respect will be made clear in the following description.

Means and effects for solving the problems

In order to solve the above-described problem, the drive device for the transport carriage according to claim 1 is a drive means for the transport object transport cart that travels along a predetermined travel path, and is provided on the transport cart side. A thrust is generated in the transport carriage by the interaction between the primary alternating magnetic field generator having a predetermined length in the traveling direction of the carriage and the alternating magnetic field generated from the alternating magnetic field generator, along the traveling path. In a DC linear motor comprising a series of secondary permanent magnet bodies arranged with NS alternating polarities at predetermined intervals, any location in the entire travel path of the transport carriage including the curved portion, In the traveling direction of the carriage of the primary-side alternating magnetic field generation device, the total length of the alternating magnetic field generation surfaces located at substantially equal intervals in the direction perpendicular to the traveling direction of the carriage faces the permanent magnets facing each other sequentially. I will do it In, wherein the determining the length in the direction perpendicular to the running direction of the transporting carriage in the permanent magnets.

According to the first aspect of the present invention, when the transport carriage travels on the travel path having the curved portion, the magnetic flux generation surface of the alternating magnetic field generator on the primary side of the linear motor installed on the transport cart side is the straight travel path. Can face the permanent magnet on the secondary side of the linear motor accurately even on a curved road.
Therefore, the thrust drop at the curved portion in the traveling path of the conveyance carriage is accurately suppressed, the operation rate of the conveyance carriage at the curved portion is not lowered, and the conveyance carriage by the linear motor is used without using a complicated bogie mechanism. This thrust can be maintained at a predetermined value or higher over the entire travel path.

According to a second aspect of the present invention, there is provided the driving device for the transporting carriage according to the first aspect, wherein the transporting cart is the driving wheel for the rail on which the transporting cart for transporting the object is laid along a predetermined traveling path. It is an automatic guided vehicle which travels by engaging with.
According to the invention according to claim 2, in addition to the effect of the invention according to claim 1 of the citation source, the efficiency improvement in the automatic transport carts such as OHS and OHT having a traveling path including a curved portion having a particularly large curvature. Can be achieved.

The drive device for the transport carriage according to claim 3 is the drive device for the transport cart according to claim 1 or 2, wherein the linear portion in the travel path of the transport cart is in a direction orthogonal to the travel direction of the transport cart. And the lengths of the alternating magnetic field generating surfaces are made equal, and the curved portion has the radius of curvature, the length of the primary alternating magnetic field generator in the traveling direction of the transport carriage, and the length in the width direction orthogonal to the traveling direction of the transport carriage. And according to this, it adjusts so that the length in the direction orthogonal to the running direction of the conveyance cart of a permanent magnet may be increased.
According to the invention according to claim 3, in addition to the effect of the invention according to claim 1 or 2, the length in the direction perpendicular to the traveling direction of the transport carriage of the permanent magnet along the curved portion of the traveling path. Can be determined to the minimum necessary.

The drive device for the transport carriage according to claim 4 is the drive device for the transport cart according to any one of claims 1 to 3, wherein the permanent magnet in the curved portion of the travel path is the travel direction of the transport cart of the permanent magnet. The center line in a direction perpendicular to the center of the curve portion is arranged and arranged so as to pass through the center of curvature of the curved portion.
According to the fourth aspect of the invention, in addition to the effects of the first to third aspects of the citation, the following effects are obtained.
That is, the linear motor primary side, the magnetic flux generating surface located in the center of the magnetic flux generating surfaces arranged in the traveling direction of the conveying cart of the alternating magnetic field generating device installed on the cart in the traveling direction of the conveying cart The center line in the direction orthogonal to the direction coincides with the direction of the center line in the direction orthogonal to the traveling direction of the conveying carriage of the permanent magnet that forms the facing secondary side of the linear motor.
Therefore, the center lines in the direction perpendicular to the traveling direction of the primary and secondary side carriages of the linear motor are slightly directional from the central part to both ends in the traveling direction of the conveyance carriage of the alternating magnetic field generator. Even if an error occurs, the error can be minimized and the thrust of the transport carriage in the curved portion can be improved as a whole with substantially no influence.

According to a fifth aspect of the present invention, there is provided the driving device for the conveyance carriage according to any one of the first to fourth aspects, wherein high-frequency non-contact power feeding is performed to the primary alternating magnetic field generation device for the conveyance carriage. This is characterized in that the high-frequency voltage obtained by this is rectified and then converted into a frequency suitable for the traveling speed of the carriage.
According to the invention according to claim 5, in addition to the effects of claims 1 to 4 of the citation source, it is necessary for various devices such as an alternating magnetic field generator installed on the conveyance carriage side and a conveyance carriage control apparatus. Power can be supplied in a non-contact manner, and the power supply mechanism of the transport carriage can be simplified and maintenance-free.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
First, the outline of the drawing will be described. FIG. 1 is a schematic plan view in which the application portions of the inventions of the present application are extracted. FIG. FIG. 3 is a cross-sectional view of an OHS showing a specific example of an apparatus for carrying out each invention of the present application.

In FIG. 1, reference numeral 11 denotes a travel path of a transport carriage (not shown), and particularly shows a curved portion. Reference numeral 12 denotes an alternating magnetic field generator installed on the transport cart, which extracts and displays the magnetic flux generation surface, and in the traveling direction (longitudinal direction) of the transport cart so as to obtain the thrust required by the transport cart. It has a predetermined length.
And the center line 12a in the advancing direction of the conveyance carriage of this alternating magnetic field generator 12 forms a straight line so as to match the straight line portion that occupies most of the travel path 12.
On the other hand, the alternating magnetic field generator 12 constitutes a linear motor, and permanent magnets are formed so that the opposing surfaces of the alternating magnetic field generator 11 are alternately NS poles along the center line 11a of the curved traveling path 11 of the transport carriage. 13 is arranged.
The basic configuration described above is equivalent to that of FIG. 4 disclosed as the prior art.

By the way, the structure which makes the summary of each invention of this application is a conveyance of a permanent magnet so that a series of each magnetic pole surface of the alternating magnetic field generator 12 can completely oppose the magnetic pole surface of the permanent magnet 13 which makes the linear motor secondary side. The direction orthogonal to the traveling direction of the carriage, that is, the length in the radial direction at the curved portion of the traveling path is set longer than the straight portion.
A means for optimizing the length in the radial direction of the curved traveling path of the permanent magnets 13 whose surface polarities are alternately arranged NS along the curved traveling path 11 will be described with reference to FIG.
2, the corresponding components shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

Now, a geometrical range of the required length in the radial direction of curvature in the curved traveling path of the conveyance carriage of the secondary permanent magnet for the linear motor is as follows.
First, the range of the curvature inward in the radial direction is the center of curvature O in the curved traveling path of the carriage, and the direction of the center of curvature O in the series of magnetic pole faces of the alternating magnetic field generator 12 is centered on this center of curvature O. is restricted by the arc S ₁ in contact with the side surfaces of the.
Next, the radially outer range of the curvature is the center of curvature O of the series of magnetic pole surfaces of the alternating magnetic field generator 12 at the center of curvature O of the curved traveling path of the carriage. is restricted by the arc S ₂ containing the side surface of the opposite direction to the.

By the way, in the curve travel part 11, the center line of the direction orthogonal to the traveling direction of the conveyance trolley in each permanent magnet is arrange | positioned toward the radial direction from the center of curvature in a curve travel part.
Therefore, among the series of magnetic pole faces in the alternating magnetic field generator 12, the center line of the magnetic pole face located in the center of the magnetic pole face in the direction orthogonal to the traveling direction of the transport carriage coincides with the center line of the permanent magnet 13, As the magnetic field generator 12 proceeds to both ends in the traveling direction of the transport carriage, the misalignment angle increases between the center lines of the magnetic pole surface of the alternating magnetic field generator 12 and the permanent magnet 13 facing the magnetic pole surface.

This maximum deviation angle θ increases as the length of the series of magnetic pole faces in the alternating magnetic field generator 12 in the traveling direction of the transport carriage increases, and decreases as the radius of curvature of the curved traveling path 11 increases. .
By the way, the maximum deviation angle θ is inevitably generated because the alternating magnetic field generator 12 installed on the transport carriage needs to cope with the straight traveling road in addition to the curved traveling road 11.
It should be noted that the maximum deviation angle θ is not significantly affected when judged from the viewpoint of the conveyance efficiency of the conveyance carriage, but can be effectively used as a guideline for indicating a limit at which a predetermined operation efficiency can be maintained.

The technology that is the basis of each invention of the present application is as described above. The OHS mechanism will be described with reference to FIG. 3 as an example of a specific configuration of application.
In FIG. 3, reference numeral 21 denotes a rail frame body in a straight portion, which is formed by extrusion molding or the like, and is laid along the travel path of the transport carriage 22 in the OHS transport system. And this rail frame 21 has the left side wall 21a and the right side wall 21b which are arrange | positioned at a perpendicular direction, and the bottom face wall 21c which connected the lower end part of both side wall 21a * 21b. The left side wall 21a and the right side wall 21b are formed symmetrically. Each of the side walls 21a and 21b has an upper surface portion 21d at the upper end position. 21 d of upper surface parts are arrange | positioned in parallel with the bottom wall 21c, and are formed toward the inner side direction. The length of the upper surface portion 21d is a minimum gap through which the support member 22b of the object mounting table 22a of the conveyance carriage 22 passes when the upper surface portions 21d and 21d of the side wall portions 21a and 21b are opposed to each other. It is set to the extent that it appears. Thereby, the upper surface part 21d prevents the dust generated as the transport carriage 22 travels inside the rail frame 21 from diffusing to the outside such as a clean room.

Moreover, each side wall part 21a * 21b has the guide part 21e. The guide portion 21e is disposed in parallel to the bottom wall 21c, and the tip end portion is bent downward. When the conveyance path is branched in two directions, the guide portion 21e is configured to advance the conveyance carriage 22 in any predetermined branch direction by engagement of a guide roller for restricting a direction described later.

A support beam 21f made of an insulating material is provided between the guide part 21e and the upper surface part 21d. The support beam 21f has a C-shaped longitudinal section so as to have two tip portions. Further, the support beam 21f is attached so that the tip end portions are positioned up and down, and is attached so that the power feeding mechanism 22c is positioned between these tip end portions. Further, a primary power supply line 21g is provided at each tip of the support beam 21f. Further, the support beams 21f are arranged at a predetermined interval in the transport track direction so as to hold the primary power supply line 21g at a constant height position over the entire length of the transport track. The primary power supply line 21g is connected to a power supply device (not shown), and supplies high-frequency power from the power supply device to the power supply mechanism 22c of the transport carriage 22.

Further, the bottom wall 21c of the rail frame 21 has a groove portion 21cx disposed at the center position and a traveling portion 21i disposed symmetrically about the groove portion 21cx. Further, the permanent magnets 13 are arranged so that the magnetic poles on the surface are NS alternately along the central portion of the groove 21cx. The permanent magnet 13 is fixed by adhering to the groove 21cx with an adhesive or the like.
The permanent magnet 13 is formed by processing a ferrite magnet into a desired size. The permanent magnet 13 may be formed of a samarium cobalt magnet or a neodymium magnet.

Reference numeral 22 d denotes a fixing member for moving the power supply mechanism 22 c integrally with the transport carriage 22. Reference numeral 22e denotes a base for supporting the drive mechanism of the transport carriage 22, on which the transport carriage support member 22b, the branch control mechanism 22f, the alternating magnetic field generator 22g, and the like are fixed. In the alternating magnetic field generator 22g, the magnetic poles 12 facing the permanent magnets 13 are arranged in the traveling direction of the transport carriage 22. Reference numeral 22h denotes a traveling wheel, which is rotatably supported by the base 22e and rolls on the traveling portion 21i. A guide roller 22i is rotatably supported on the base 22e in a horizontal state and rolls on the inner surfaces of the side wall portions 21a and 21b. Reference numeral 22j denotes a direction regulating guide roller, and one of the pair of left and right direction regulating guide rollers 22j corresponds to the position based on the action of the branch control mechanism 22f according to the travel destination of the branch path of the transport carriage 22. It is configured to engage with any of the guide portions 21e.

In the configuration shown in FIG. 3, when a high frequency voltage is applied to the primary power supply line 21g, a high frequency current is generated by electromagnetic induction in the secondary winding of the power supply mechanism 22c. The power feeding mechanism 22c is connected to a current conversion unit (not shown). The current converter converts the high-frequency current into direct current in the rectifier circuit and converts it into three-phase alternating current in the PWM converter circuit, and then energizes the coil of the alternating magnetic field generator 22g to generate a traveling magnetic field. The transport carriage 22 receives thrust based on the electromagnetic action of the traveling magnetic field and the magnetic flux generated from the permanent magnet 13, travels along the rail frame 21 laid along the travel path of the transport carriage 22, and travels. A braking force can be applied to the transport carriage 22 by controlling the magnetic field.

Note that the travel direction of the transport carriage of the permanent magnet 13 on the straight traveling path is the straight line portion at the boundary between the straight path and the curved path on the travel path of the transport carriage 22 until the direction of the transport carriage 22 is completely in the straight line direction. It is preferable that the length in the direction orthogonal to the direction is gradually shortened.

It is the schematic plan view which extracted the application location of each invention of this application. It is a schematic diagram which shows the relationship between the primary side alternating magnetic field generator of the linear motor in the curve part among the travel paths of a conveyance trolley, and the permanent magnet which faces this magnetic pole surface. It is sectional drawing of OHS which shows the specific example of the apparatus which implements each invention of this application. It is a principal part top view for demonstrating the conventional structure.

Explanation of symbols

12 ... Magnetic pole 13 ... Permanent magnet 21 ... Rail frame 21b ... Right side wall 21c ... Bottom wall 21cx ... Groove part 21d ... Upper part 21e ... Guide part 21f ... Support beam 21g ... Primary Feed line 21i ··· Traveling part 22 ··· Carriage carriage 22a · · Transported object placement table 22b · · Support member 22c · · Feeding mechanism 22d · · Fixing member 22e · · Base 22f · · Branch control mechanism 22g ··· Alternating magnetic field generator

Claims (5)

A driving means for a carriage for transporting an object to be transported that travels along a predetermined travel path, provided on the transport carriage side, having a predetermined length in the traveling direction of the carriage, a primary alternating magnetic field generator,
A series of secondary side permanent magnets that generate thrust on the transport carriage by interaction with the alternating magnetic field generated by the alternating magnetic field generator and are arranged with NS alternating polarity at predetermined intervals along the travel path. A magnet body;
In a linear motor consisting of
At any location in the entire travel path of the transport carriage including the curved portion, the carts of the alternating magnetic field generation surfaces located at substantially equal intervals in the travel direction of the carriage of the primary alternating magnetic field generator. A driving device characterized in that the length of each permanent magnet in a direction orthogonal to the traveling direction of the transport carriage is determined such that the total length in the direction orthogonal to the traveling direction faces each permanent magnet that is sequentially opposed. Have a transport cart.   2. The drive device according to claim 1, wherein the carriage for transporting the object to be transported is an automatic guided carriage that travels by engaging a traveling wheel with a rail laid along a predetermined traveling path. Have a transport cart.   The straight line portion in the travel path of the transport carriage equalizes the lengths of the permanent magnet and the alternating magnetic field generating surface in the direction orthogonal to the travel direction of the transport carriage, and the curved portion is the curvature radius and the primary alternating magnetic field generator. Adjusting the length of the permanent magnet in the direction perpendicular to the traveling direction of the transport carriage according to the length in the traveling direction of the transport carriage and the length in the width direction orthogonal to the traveling direction of the transport carriage. A conveying cart having the driving device according to claim 1. 2. The permanent magnet in the curved portion of the traveling path is arranged so that a center line in a direction orthogonal to the traveling direction of the carriage of the permanent magnet passes through the center of curvature of the curved portion. A conveying cart having the driving device according to any one of claims 1 to 3. For the primary alternating magnetic field generator of the transport carriage, high-frequency non-contact power feeding is performed, and after the high-frequency voltage obtained by this is rectified, it is converted to a frequency that matches the traveling speed of the transport carriage. A transport cart having the drive device according to any one of claims 1 to 4.

Images