JPH0124690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus that uses a linear motor as a drive source and is capable of conveying a relatively long distance.
In particular, it relates to one in which the excitation coil is a stator.

Most of conventional conveyance devices using a linear motor as a drive source are of a type in which the excitation coil of the linear motor itself moves. This method had drawbacks such as heavy transport weight and the need for a sliding device to supply power to the excitation coil. On the other hand, there is also a method in which excitation coils are distributed along the conveyance path to drive the mover. However, this system is economically disadvantageous unless the transport density is high, so it was used for special purposes such as reducing the installation space. Each excitation coil was supplied with current from one drive device. This type of method was not originally intended to extend or expand the conveyance path.
Although it can be said to be suitable for this purpose, it is inconvenient when changing or adding to the conveyance route.
In addition, each pallet on the conveyance path is moved simultaneously,
It also had the disadvantage that it had to be stopped at the same time. Therefore, controllability was poor and freedom of control was lacking. Furthermore, since current must be supplied to coils that do not contribute to the movement of pallets, there is also the disadvantage that electric power is not used effectively. These drawbacks have hindered the spread and development of conveying devices using linear motors. However, linear motors are suitable for reducing the installation space and providing high-speed, high-performance devices, and it has been desired to realize a conveyance device using linear motors that eliminates the drawbacks of the conventional ones.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the purpose of the present invention is to rectify the drawbacks of the conventional technology. An object of the present invention is to provide a motorized conveyance device.

In order to achieve this object, the linear motor type conveyance device according to the present invention includes an excitation coil, a detector that detects at least one of the relative position and speed between the coil and the pallet, and the above-mentioned A drive unit that supplies a drive current to an excitation coil is used as a drive unit, and these units are distributed along a plurality of rails. However, the drive unit in each drive unit is provided in common to each drive unit, and is connected to a drive unit from each drive unit. The system is designed to control the supply of drive current to the excitation coil based on the detector detection information and the operation command for the drive unit from the operation control device that processes pallet stop/sending requests and the detector detection information. It is. In this case, a detector for detecting stoppage of the pallet may be provided between the drive units.

Next, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a perspective view showing one embodiment of the present invention. In this figure, 1 is the pallet on which the object to be transported is mounted, 2 is the rail for supporting and guiding the pallet, 31 and 32 are the excitation coils of the linear motor that drives the pallet 1, and 41 and 42 are the excitation coils for the pallet 1, respectively. Detectors 51 and 52 are used to detect whether or not the pallet 1 exists near the pallets 31 and 32, or whether its position or velocity is at a desired value. This is a drive device that controls driving force. In this case, the excitation coil 31, the detector 41, and the drive device 51 constitute one drive unit, while the excitation coil 32, the detector 42, and the drive device 52 constitute another drive unit.

The operation of this device having the above configuration is as follows.
That is, the pallet 1 also serves as the secondary conductor of the linear motor, and when the pallet 1 enters the range that can be driven by the excitation coil 31, it is detected by the detector 41, and the pallet 1 for the excitation coil 31 is detected. Detect the relative position and speed of 1. This detection signal is sent to the drive device 51. The drive device 51 uses the configuration and operation described later to check whether this detection signal matches a command given separately in advance, and controls the amount of excitation of the excitation coil 31 so that the pallet 1 operates according to the command. do. This command may be, for example, to stop the pallet 1 near the excitation coil 31 or to accelerate it to a certain speed. Such a command may be given manually by a person, for example, by providing an operating device in the drive device, or may be given from the common operation control device 6.

The above is a case where the pallet 1 is located near the excitation coil 31. In this case, the detector 42, which cooperates with the excitation coil 32 and the drive device 52 to constitute one drive unit, detects when the pallet 1 By detecting that the excitation coil 32 is out of the range that can be driven by the excitation coil 32, the drive device 52 is prevented from exciting the excitation coil 32 wastefully. On the other hand, assume that the pallet 1 is driven by the excitation coil 31 and comes near the excitation coil 32. Then, the detector 42 detects this and sends a detection signal to the drive device 52. As a result, the drive device 52 operates, checks whether the position and speed detection signals from the detector 42 match the commands given separately in advance, and controls the excitation coil 32 so that the pallet 1 operates according to the commands. Controls the amount of excitation.
The command to the drive device 52 is, for example, to stop the pallet 1 near the excitation coil 32, or to accelerate it to a certain speed. Such a command may be given manually, for example, by providing an operating device on the drive device, or may be given from the operation control device 6.

Figure 2 shows a drive device 5 that performs the above-mentioned actions.
1 (or 52). In the same figure, 31 is an excitation coil of a linear motor, and in this embodiment, a three-phase AC system is targeted.
It is excited by a three-phase AC power supply having terminals U, V, and W via bidirectional thyristors a1, a21, . . . , a31. In the case of positive phase excitation, the bidirectional thyristors a1, a21, and a31 are used for excitation, and in the case of negative phase excitation, the bidirectional thyristors a1, a22, and a33 are used for excitation. Reference numeral b designates a switching circuit that performs such forward/reverse phase switching by opening and closing gate signals to these bidirectional thyristors. c is a phase shifter that controls the phase of the gate pulse in order to control the conduction time of the bidirectional thyristor. d is a speed controller that has a speed control function by comparing, calculating, and amplifying the speed target value from e described later and the speed detection value from the speed detector 4a and supplying an analog output to the phase shifter c. . The polarity and magnitude of the analog output change depending on the operating state of the transport device. If the magnitude is large, the phase shifter c is operated to increase the amount of excitation of the excitation coil 31, while the switch b is operated to select the forward or reverse excitation direction depending on the polarity of the analog output. make it work. That is, switch b is speed controller b
Depending on the polarity of the analog output of
Select which one to pass through a32. In this case, the switch b may include a function of amplifying the pulse signal from the phase shifter c to some extent. On the other hand, e
is a position controller which has a position control function by comparing, calculating, and amplifying the position target value A and the position detection value from the position detector 4b. Although the output of the position controller e is shown as the control input of the speed controller d in FIG. 2, it may also be transmitted directly to the phase shifter c and the switching device b without providing the speed controller d. Further, in this embodiment, the position target value A as a command is set to the position controller e.
However, if there is no need to control the position and only speed control is required, the position controller e is not provided and the position target value A as a command is used to directly control the speed. It is also possible to add it to container d. In this way, in the present invention, each drive device 51, 52, etc. may be one that controls both position and speed, or may be one that controls only one of them. The speed detector 4a and the position detector 4b are the detector 41 (or 42) in FIG.
It may be included in the above, or it may be an appropriate modification thereof.

As described above, in the present invention, one excitation coil, one detector, and one driving device constitute one driving unit. Therefore, for the purpose of extending the conveyance device, by adding such a drive unit,
This purpose can be easily achieved. Also,
Changing the stop position can be easily done by changing the position of the excitation coil. In addition, if the rails are divided into short sections and corresponded to drive units, route changes can be easily made. In such a case, if the driving power is relatively small, the power for each group of driving devices can be supplied from a common power source of 100V or 200V of commercial frequency.

The drive device has a simple structure consisting of a power circuit made of transistors or thyristors and its control circuit, and has been made smaller and smaller using integrated circuit technology.
Lower prices can be easily achieved. Excitation coils can also be mass-produced due to recent developments in automatic winding technology. Although any type of linear motor may be used, it is advantageous to use an induction motor, which is simple in construction, relatively inexpensive, and generates a strong thrust up to high speeds. However, systems using induction motors have generally been considered to have poor controllability, and have rarely been used for positioning control.

However, in the embodiment of the present invention, by using an induction motor, it is possible to stop a 54 kg load (inner pallet load 19 kg) at a speed of about 1 meter per second with an accuracy within ±10 mm in about 1 to 2 seconds. did it. (The main specifications of the device in this case are as follows: power supply 3-phase, 50Hz,
200V, rated current 3.2A (30 minutes), the linear motor control method uses a combination of voltage control and phase switching, and the synchronous speed is 4.6m/s using thyristor phase control. ) In this way, a device with very good controllability was obtained.

By the way, when the configuration of this device as described above, that is, a large number of driving units of excitation coils, detectors, and drive devices, exist on one conveyance path, the number of pallets also increases, and automatic operation of pallets is difficult throughout the conveyance path. It is convenient to carry out management.

6 in FIG. 1 is a traffic control device used for such purpose. The operation control device 6 receives information regarding pallets from each drive device, automatically clarifies the desired state of operation control based on the information, and sends commands to each drive device based on the result.
Such a device can be easily realized using a microcomputer or the like.

FIG. 3 is a block diagram showing an example of the traffic management device 6. As shown in FIG. In the figure, signals P51, B51, P5
2, take in B52 and send out signals A51, A52. The symbols 51 and 52 attached to these signals refer to the drive devices 51 and 5 in FIG.
Indicates that it is related to 2. In addition, in this
B51 is the output signal B from the position detector 4b shown in FIG. 2, and B52 is the output signal from the position detector corresponding to the drive device 52. Also, A5
1 is the position target value A shown in FIG. 2, and A52 is for the drive device 52. On the other hand, P5
1 and P52 are request signals indicating whether the excitation coils 31 and 32 should stop or send out the pallet, respectively. These request signals P5
1, P52 is generated automatically by another device related to the conveyance device, for example, depending on the progress of the assembly robot, or by manual operation. The position sensor signals B51 and B52 are fed into signal converters CE51 and CE52, respectively, which in turn lead to excitation coils 31 and 3, respectively.
It is determined whether a palette exists in the action range of 2. This discrimination signal is sent to the microcomputer MC via the signal transmission bus BUS. On the other hand, commands P51 and P52 are also sent to the microcomputer MC via the bus BUS. The microcomputer MC uses these signals to determine whether the drive devices 51 and 52 should perform stop control or feed control, and
Sends a signal to MC51 and MC52. The signals of the memories MC51 and MC52 are level switch
CC51 and CC52, and are switched to signals A51 and A52 of an appropriate form, for example analog quantities and appropriate magnitudes, and are sent to the drive devices 51 and 52.
It is sent out as the position target value A.

The operations performed by the microcomputer MC in order to realize the functions of the traffic management device described above are shown in flowchart form in FIG. 4. block
In BLK1, give the value 1 to the variable n. This variable n specifies the order of the excitation coils 31, 32, etc., and by giving the numerical value 1, this specification indicates that the excitation coil 31 is specified. After that, in block BLK2, the excitation coil 3
It is determined whether the request No. 1, that is, the command P51 in FIG. 3, is "stop" or "feed". If this request is "stop", block BLK3, and on the other hand,
If the request is "send", the process moves to block BLK4. In block BLK3, the control is instructed to "stop", which causes the positional target value A to be set to zero in FIG. On the other hand, block
In BLK4, it is determined whether or not another pallet exists in the adjacent excitation coil in the direction in which the pallet is to be sent. For example, if the number of adjacent excitation coils is 32, the determination is made based on the position detector signal B52. As a result of this determination, if a pallet exists, the process is transferred to block BLK3 and control is set to "stop" in order to prevent a collision. On the other hand, if the palette does not exist, the process is transferred to block BLK5 and the control is instructed to "send". As a result, the position target value A in FIG. 3 is set outside the action range of the excitation coil 31, for example, at the position of the excitation coil 32. In this case, the drive device 51 and the excitation coil 31 accelerate the pallet and send it out in the direction of the excitation coil 32. Due to inertia, the delivered pallet maintains a certain speed or more and heads toward the exciting coil 32. As above, block
When the processing of BLK3 or BLK5 is completed, the processing is moved to block BLK6. Here, the value of n is 1
and set the value to 2. Here, it is determined whether this value exceeds the total number n _nax of excitation coils, and if it does not, the process is transferred to block BLK2 using that value of n, and the above-mentioned process is thereafter performed in the same manner. When the processing progresses and n becomes n _nax , the processing is transferred to BLK1 again, and the same processing is repeated again with n set to 1.

The above processing can be performed for one block by a microcomputer in a few microseconds to more than ten microseconds, so the processing of all the blocks in Fig. 4 for one numerical value of n can be performed in several microseconds. This can be done in about 10 microseconds. Therefore, even in a conveyance path where 20 to 30 excitation coils exist, the time required to process all n _naxs is only 10 milliseconds at most. The processing is performed by repeatedly updating every 10 milliseconds or so. Such processing speed is much faster than the pallet travel speed and is practically negligible.

As explained above, by providing the operation control device 6, it is possible to achieve reliable and high performance with a device having a simple structure as a whole without complicating the distributed excitation coils, detectors, and drive devices. Operation management can be performed.

By the way, in the case of the configuration shown in FIG. 1, even if the excitation coils 31 and 32 are spaced apart to some extent,
The inertia of the pallets allows them to be fed to adjacent drive units without stopping in between. Therefore, each drive unit can be spaced apart to some extent. However, it cannot be said that such a stoppage can be absolutely avoided, so countermeasures must be taken in the unlikely event of a stoppage. One such measure, as shown in FIG. 1, is to provide a detector 400 between the dispersed excitation coils to detect the stoppage of the pallet. If such an intermediate detector is installed and it is detected that the pallet has stopped in the intermediate position, an alarm such as a bell or siren will sound.
Such a pallet can be artificially transferred to a given excitation coil. Alternatively, by sending the signal from the intermediate detector to the traffic control device 6, for example,
It is also possible to stop transporting all pallets.

If such a method is used, the installation interval of the excitation coils can be expanded as much as possible, so the number of drive units can be reduced. In other words, the present invention is effective in further reducing equipment costs.As described above, the present invention realizes a highly versatile linear motor type conveying device, which requires a small installation space, requires no maintenance, and has high speed and high performance. A transport device can be realized. It has good controllability and a large degree of freedom in control.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a linear motor type conveyance device according to the present invention, FIG. 2 is a block diagram showing an example of a drive device, and FIG. 3 is a block diagram showing an example of the configuration of a traffic management device. FIG. 4 is a flowchart showing an example of the operation of the traffic management device. 1... Palette, 2... Rail, 31, 32...
...excitation coil, 41,42,400...detector,
51, 52... Drive device, 6... Traffic control device,
a1, a21, a22, a31, a32...bidirectional thyristor, b...switching circuit, c...phase shifter,
d...Speed controller, e...Position controller, 4a...
Speed detector, 4b...Position detector, BUS...Signal transmission bus, CC51, CC51...Level converter, CE51, CE52...Signal converter, MC...
Microcomputer, MC51, MC52...
memory.

Claims (1)

[Claims] 1. An excitation coil of a linear motor is used as a stator,
It is a linear motor type conveyance device that conveys an object mounted on a pallet by driving a mover fixed to the pallet that can run on a rail. A drive unit includes a detector that detects at least one of the relative position and speed with respect to the pallet, and a drive device that supplies a drive current to the excitation coil.
The units are distributed along a plurality of rails, and the drive device in each drive unit has an operation management system that is provided in common to each drive unit and processes detector detection information and pallet stop/delivery requests from each drive unit. Excitation is performed by feedback control regarding at least one of the pallet position and speed based on the target value regarding at least one of the pallet position and speed for the drive unit from the device and the detector detection information. A linear motor type conveyance device characterized by a configuration that controls the supply of drive current to a coil. 2. The linear motor according to claim 1, wherein a detector for detecting pallet stoppage is provided at an intermediate position between each of the distributed drive units and the drive unit adjacent to the drive unit. Type conveyance device.