JPH0458247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a levitation type conveyance device suitable for conveying small items, and particularly relates to a levitation type conveyance device capable of stably controlling a magnetic levitation system. . [Technical background of the invention and its problems] In recent years, as part of office automation and factory automation, slips, documents, cash, samples, etc. have been moved between multiple points within a building using transport devices. It is being done. Conveying devices used for such purposes must not harm the office environment, and must not generate dust or the like and have low noise. For this reason, this type of transport device is configured to be able to support the transport vehicle in a non-contact manner with respect to the guide rail. To support a guided vehicle without contact, it is common to use air or magnetism, but methods that use magnetic attraction to support the guided vehicle have improved followability to guide rails and noise reduction. It is highly effective and is considered the most promising support method. Among such floating conveyance devices using a support system using magnetic attractive force, the present applicant has previously proposed a device using permanent magnets as a magnetic support unit. According to this device, most of the magnetomotive force required to levitate the carrier can be obtained from the magnetomotive force of the permanent magnets, so the excitation current of the electromagnets can be reduced, resulting in energy savings. By the way, in a normal office environment, there are many obstacles, so the configuration of the conveyance path is often complicated. Considering this point, it is desirable that the guide rail has a split structure. This is because if the guide rail is made into a divided structure in this way, the installation work can be simplified. However, if the guide rail is made into a split structure, the joint portion will be perpendicular to the traveling direction of the transport vehicle. Of course, if the magnetic circuit formed by the magnetic support unit, the air gap, and the guide rail is parallel to the joint, the magnetic resistance of this magnetic circuit will not change significantly even if the carrier passes through the joint. However, in this type of transport device, there is a demand for the guide rail to be as narrow as possible due to space constraints, and to meet this demand, the direction of travel of the transport vehicle and the magnetic circuit must be arranged parallel to each other. This is desirable. In addition, even if the magnetic circuit is set in a direction perpendicular to the traveling direction of the transport vehicle, there are cases where the transport vehicle must be branched at right angles to the previous direction of travel due to constraints on the construction of the transport path. will also occur. At this time, the magnetic circuit formed by the magnetic support unit after branching is different from before branching, and is parallel to the traveling direction of the carrier, and is perpendicular to the joint when passing through the joint.
In this case, as shown in FIG. 6, the magnetic resistance of the magnetic circuit formed by the magnetic support unit 1, the air gap, and the guide rail 2 increases, and the magnetic resistance between the magnetic unit 1 and the guide rail 2 increases. Suction power decreases. For this reason, it is necessary to take measures to increase the magnetic attraction force by temporarily increasing the excitation current of the electromagnet at the joint, but even if such measures are taken, the transport vehicle may vibrate or the excitation current may be increased. If the fluid flows more than necessary, problems such as the magnetic support unit and the guide rail being attracted to each other may occur. If such a problem occurs, it not only impairs the stability of the magnetic support control system but also wastes power. [Object of the Invention] The present invention was made in view of the above circumstances, and its purpose is to set a magnetic circuit parallel to the traveling direction of a conveyance vehicle traveling along a guide rail with a split structure. It is an object of the present invention to provide a levitation type conveyance device that can prevent the magnetic attraction force from being significantly reduced at the joint portion of the guide rail even when the magnetic levitation system is stabilized at all times. [Summary of the Invention] The present invention provides a guide rail formed by connecting a plurality of rail segments made of ferromagnetic material in series, a carrier disposed so as to be freely movable along the guide rail, and the carrier. a magnetic support unit equipped with an electromagnet that is mounted on the guide rail and faces the lower surface of the guide rail through an air gap, and stabilizes a magnetic circuit through which the magnetic flux generated by the magnetic support unit passes by controlling the excitation current of the electromagnet. The floating conveyance device is characterized in that the connecting end portions of the rail division bodies are formed as follows. That is, in a section where the magnetic support unit generates magnetic flux along a plane parallel to the traveling direction and the vertical direction of the conveyance vehicle, the connecting end of the rail division body is parallel to the plane and in the direction of the magnetic circuit. It is characterized by having a portion longer than the length in the traveling direction. [Effects of the Invention] According to the present invention, in the section where the magnetic flux generated by the magnetic support unit is aligned along a plane parallel to the traveling direction and the vertical direction of the carrier,
Even when the guided vehicle passes through the joint of the guide rail, the connecting end of the rail segment is parallel to the traveling direction of the guided vehicle and the vertical direction, and the magnetic flux generated by the magnetic support unit passes through the magnetic circuit. Since a portion longer than the length is provided, all of the magnetic flux does not cross the joint portion, and the magnetic resistance does not vary significantly. Therefore, the magnetic attractive force between the magnetic support unit and the guide rail does not fluctuate at the joint portion of the guide rail. Therefore, according to the present invention, it is possible to stabilize the magnetic levitation system, and since the excitation current does not flow more than necessary, it can also contribute to energy saving. Of course, since the guide rail has a divided structure, installation performance will not be impaired. [Embodiment of the Invention] Hereinafter, a floating conveyance device according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 11 denotes a track frame having an inverted U-shape in cross section and laid, for example, in an office space to avoid obstacles. Two guide rails 12 are provided on the lower surface of the upper wall of this track frame 11.
a and 12b are laid in parallel, and the track frame 11
On the inner surface of the side wall, emergency guides 13a and 13b each having a U-shaped cross section are laid with their open sides facing each other. Guide rails 12a, 12b
Below the guide rail 12, the transport vehicle 15
They are arranged so as to be freely movable along lines a and 12b.
Further, a stator 16 of a linear induction motor is arranged at a portion between the guide rails 12a and 12b on the lower surface of the upper wall of the track frame 11 at a predetermined distance apart along the guide rail. The guide rails 12a and 12b are formed by applying white paint to the lower surface of a band-shaped member 21 formed of a ferromagnetic material, and have a divided structure to facilitate installation work in an office. The joint portion A of each band-shaped member 21 is a portion a extending in the width direction of the member 21 from the inner side end portion to the center portion of the member 21.
1, a portion a2 extending from this portion a1 in the length direction of the member 21, and a portion a2 extending from this portion a2 to the member 21.
It has a stepped shape including a portion a3 extending in the width direction toward the outer side end portion. A portion a2 extending in the length direction of the member 21 is set to be longer than the length of a magnetic circuit in the traveling direction of the conveying vehicle through which magnetic flux generated by a magnetic support unit 31 , which will be described later, passes. This joint portion A has been subjected to a predetermined joining process. Next, the configuration of the transport vehicle 15 will be explained. That is, a flat base 25 is arranged so as to face the lower surfaces of the guide rails 12a and 12b.
This base 25 includes two dividing plates 26a, 26b arranged in the direction of movement, and both dividing plates 26a, 26b.
and a connecting mechanism 27 that rotatably connects the two in a plane orthogonal to the traveling direction. This base 2
A total of four magnetic support units 31 are mounted at each of the four corners of the upper surface of the magnetic support unit 5. These magnetic support units 31 are attached to the base 25 using bolts and pedestals 33 (not shown) on the upper surface of the base 25 . These magnetic support units 31
The unit 31 and guide rails 12a, 1
An optical gap sensor 34 is attached to detect the gap length between the gap 2b and the lower surface of the gap 2b. Further, two sets of connecting members 3 are provided on the lower surface of each dividing plate 26a, 26b.
Containers 37, 38 for receiving goods to be transported via 5
are installed respectively. These containers 37 and 38 are provided with a control device 41 for controlling each of the four magnetic support units 31,
A total of four constant voltage generators 42 and two small-capacity power supplies 43 for supplying power to these are installed. In addition, at the four corners of the lower surface of the base 25 , there are provided guides for supporting the transport vehicle 15 in the vertical direction by contacting the inner surfaces of the upper and lower walls of the emergency guides 13a and 13b when the magnetic force of the magnetic support unit 31 is lost. The transport vehicle 1 contacts the four vertical wheels 45a and the inner surfaces of the side walls of the emergency guides 13a and 13b.
Four horizontal wheels 45 for supporting 5 in the left and right direction
b are attached respectively. In addition, base 2
Reference numeral 5 also serves as a conductor plate which is a movable element of the linear induction motor described above, and is placed at a height facing the stator 16 with a slight gap in between when the device is in operation. The magnetic support unit 31 includes two electromagnets 51 and 52 arranged in a direction parallel to the traveling direction of the transport vehicle 15 so that the upper end faces the lower ends of the guide rails 12a and 12b, and these electromagnets 51 and 52 .
and a permanent magnet 53 interposed between each lower side surface of the magnet, and has a U-shape as a whole. Each of the electromagnets 51 and 52 includes a yoke 55 made of a ferromagnetic material and a coil 56 wound around the yoke 55 . They are connected in series in such an orientation that the magnetic fluxes formed by 52 add to each other. Further, the control device 41 is configured as shown in FIG. 2, for example. In this figure, arrows indicate signal paths and bar lines indicate power paths. This control device 41 includes a sensor section 61 that is attached to the transport vehicle 15 and detects changes in magnetomotive force or magnetic resistance in the magnetic circuit formed by the magnetic support unit 31 or changes in the motion of the transport vehicle 15 .
and an arithmetic circuit 62 that calculates the power to be supplied to the coil 56 based on the signal from the sensor section 61.
A power amplifier 63 supplies power to the coil 56 based on the signal from the arithmetic circuit 62.
The four magnetic support units 41 are assembled to control the four magnetic support units 41, respectively. The sensor section 61 is comprised of a modulation circuit 64 that modulates the signal of the optical gap sensor 34 described above in order to suppress the influence of external noise, and a current detector 65 that detects the current value of the coil 56. On the one hand, the arithmetic circuit 62 is connected to the optical gap sensor 3.
4 is introduced through a modulation circuit 64, a gap length setting value _Z0 is subtracted by a subtracter 66, and the output of this subtracter 66 is fed directly or via a differentiator 67, respectively. On the other hand, the signal from the current detector 65 is guided to a feedback gain compensator 70;
5 and is compared with the O signal in the subtracter 71, and then compensated in the integral compensator 72, and the signal introduced in 3 above.
A subtracter 74 compares the summed outputs of the adders 73 of the three feedback gain compensators 68 to 70, and outputs the difference to the power amplifier 63. Further, the constant voltage generator 42 is interposed between the power supply 43 and the control device 41, and the modulation circuit 6
4. Arithmetic circuit 62 and optical gap sensor 34
It always supplies current at a constant voltage. This constant voltage generator 42 is for eliminating the influence of voltage drop caused by load fluctuation of the power supply 43 on the control device 41, and is connected to a reference voltage generator 75 and the output signal of this reference voltage generator 75. The current amplifier 76 always supplies the required current to the control device 41 at a constant voltage. Next, the operation of the floating conveyance device according to this embodiment configured as described above will be explained. When the device is in a stopped state, the vertical wheels 45a of the transport vehicle 15 are in contact with the inner surface of either one of the upper and lower walls of the emergency guides 13a, 13b. When the device is started in this state, the control device 41 causes the electromagnets 51 and 52 to generate magnetic flux in the same direction or in the opposite direction to the magnetic flux generated by the permanent magnet 53, and also causes the magnetic support unit 31 and the guide rail 12 to generate magnetic flux in the same direction or in the opposite direction.
The current flowing through the excitation coil 56 is controlled to maintain a predetermined gap length between the excitation coil 56 and the excitation coil 56. As a result, as shown in FIG. 3a, the permanent magnets 53 to
Yoke 55 ~ Gap P ~ Guide rails 12a, 12b
A magnetic circuit consisting of a path from ~gap P~yoke 55~permanent magnet 53 is formed. The magnetic flux φ formed in this magnetic circuit is generated along a plane parallel to the traveling direction of the carrier 15 and the vertical direction, as shown in FIG. The gap length is determined by the weight of the supported object such as the transport vehicle 15 and the magnetomotive force of the permanent magnet 53 between the magnetic support unit 31 and the guide rails 12a, 12b.
The length is set so that the magnetic attraction force between the two ends is exactly balanced. The control device 41 controls the excitation currents of the electromagnets 51 and 52 to maintain this gap length. This results in so-called zero power control. Assuming that the carrier 15 is located directly below the stator 16 of the linear induction motor, when this stator 16 is energized, the base 25 receives electromagnetic force from the stator 16, so the carrier 15 is placed in a magnetically levitated state. As it is, it starts running along the guide rails 12a, 12b.
If the stator 16 is placed again before the carrier 15 comes to a complete standstill due to the influence of air resistance, the carrier 15 will be energized again and the guide rails 12a,
12b. This movement continues until the destination point. In this way, the transport vehicle 15 can be moved to the destination point in a non-contact manner. According to this embodiment, even when the transport vehicle 15 passes through the joint A of the guide rails 12a and 12b during the movement process, as is clear from FIG. 15 and the direction in which the magnetic flux φ is generated, the magnetic flux φ does not completely cross the joint portion A. Therefore, changes in magnetic resistance can be suppressed, and control performance when passing through the joint can be stabilized. In addition, in the device of this embodiment, the guide rail 1
2a, 12b, or a change in the center of gravity of the transport vehicle 15 , create a gap that will cause the permanent magnets 53 to generate an attractive force that is commensurate with the weight that each magnetic support unit 31 should support. must be secured between each magnetic support unit 31 and the guide rails 12a, 12b. In this case, the dividing plate 26a rotates relative to the dividing plate 26b around the coupling mechanism 27, and each magnetic support unit 31
acts to maintain an appropriate gap length. Note that the present invention is not limited to the embodiments described above. For example, in the above embodiment, the joint portion A has a staircase shape, which is different from the guide rail 12.
There are no limitations on the shape of the joining portions of the strip members 21 forming the strips 12a and 12b, and the guide rails 12a and 12b may be connected at their respective side end surfaces, as shown in FIG. 4, for example. With this configuration, even if the floating conveyance device is in an environment with large temperature differences, it is possible to absorb dimensional deviations due to thermal expansion of the guide rails 12a and 12b without significantly affecting the suction force of the magnetic support unit 31 . It has the advantage of being possible. Alternatively, as shown in FIG. 5, the joint portion A may be shaped like a plurality of steps, and each portion parallel to the traveling direction of the transport vehicle 15 may be longer than the length of the magnetic circuit in the traveling direction. In this example, seam part A
Since there are three portions extending in the width direction of the guide rails 12a and 12b, the joint portion A crosses the magnetic flux by at most 1/3 of the width of the guide rails. Therefore, more stable control is possible than in the example described above. This effect increases as the number of steps in the stepped portion increases. In addition, by using a ferromagnetic joint fitting on the upper and lower surfaces of the track frame 11 in contact with the joint part A, the magnetic circuit formed by the magnetic support unit 31 , the air gap P, and the guide rails 12a and 12b is further enhanced at the joint part A. You may try to keep it in a stable state. Furthermore, it goes without saying that the present invention is also applicable to a floating conveyance device that uses only electromagnets as the magnetic support unit.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic configuration of a floating transfer device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an electrical configuration of a control device of the same device, and FIG. 3 a
is a partially cutaway side view showing the magnetic circuit of the device;
Figure b is a front view with the same part cut away, Figures 4 and 5 are diagrams for explaining floating conveyance devices according to other embodiments of the present invention, and Figure 6 is a conventional floating conveyance device. FIG. 1, 31 ...magnetic support unit, 2, 12a, 1
2b... Guide rail, 11... Track frame, 13a, 1
3b...Emergency guide, 15 ...Transportation vehicle, 16...Stator of linear induction motor, 25...Base, 26a, 2
6b...dividing plate, 27...coupling mechanism, 34...gap sensor, 37, 38...container, 41...control device, 4
2... Constant voltage generator, 43... Power supply, 51, 52...
Electromagnet, 53...Permanent magnet, 55...Yoke, 56...Coil, A...Joint portion, P...Gap.

Claims (1)

[Scope of Claims] 1. A guide rail formed by connecting a plurality of rail segments made of ferromagnetic material in series, a carrier disposed so as to be freely movable along the guide rail, and a vehicle mounted on the carrier. a magnetic support unit having an electromagnet facing the lower surface of the guide rail with an air in between; and control for controlling the excitation current of the electromagnet to stabilize a magnetic circuit through which the magnetic flux generated by the magnetic support unit passes. In the floating conveyance device, in a section where the magnetic support unit generates magnetic flux along a plane parallel to the traveling direction and the vertical direction of the conveyance vehicle, the connecting end of the rail segment is connected to the A floating conveyance device comprising a portion parallel to a plane and longer than the length of the magnetic circuit in the traveling direction. 2. The magnetic support unit includes the electromagnet, and a permanent magnet that is interposed in a magnetic circuit composed of the electromagnet, the guide rail, and the air and supplies the magnetomotive force necessary to levitate the carrier. A floating conveyance device according to claim 1, characterized in that: 3. The floating conveyance device according to claim 1, wherein the connecting portions of the rail division bodies are connected by a ferromagnetic joint fitting. 4. The floating conveyance device according to claim 3, wherein the joint fitting is integrally formed with an element that supports the guide rail.