JP3235708B2 - Transfer equipment using linear motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a linear motor driving coil provided with a driving coil for a linear motor on a moving body side, and a magnet forming a linear DC motor together with the driving coil on a guide rail side for guiding the moving body. The present invention relates to a transfer facility using a linear motor provided in a state where magnetic poles with respect to the driving coil are alternately arranged along a moving direction of the moving body.

[0002]

2. Description of the Related Art Such a transfer equipment utilizing a linear motor includes:
This is a facility that travels and drives a moving body loaded with various loads by the thrust of a linear DC motor to transport various loads.
In such transport equipment, it is necessary to obtain position information of the moving body in order to control the traveling of the moving body.
A moving body is provided with a rotating body that rotates in contact with the ground side and a rotary encoder that detects a rotation amount of the rotating body, and position information of the moving body is obtained based on a detection signal of the rotary encoder.

[0003]

However, in the above-mentioned conventional configuration, since the rotating body for detecting the position information is in contact with the ground side, the rotating body may be deformed due to wear or the rotating body may come into contact. If the part is not flat, etc., the position information obtained from the detection signal of the rotary encoder will include an error, and furthermore, when the moving body runs in a clean room, the contact between the rotating body and the ground side will occur. Dust generation is a problem. In addition, a mechanical component such as a rotating body is required, which disadvantageously complicates a configuration for detecting position information. The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain position information of a moving body with high accuracy while having a simple configuration.

[0004]

According to the present invention, the detection signal of the magnetic sensor changes with the movement of the moving body. Since the change in the detection signal of the magnetic sensor corresponds to the arrangement of the magnets of the linear induction motor in which the directions of the magnetic poles are alternated along the moving direction of the moving body, the position detecting means is provided with respect to the position of the moving body. From the detection signal of the substantially sinusoidal magnetic sensor, it is possible to know how much magnet the moving body has moved,
The position information of the moving object can be detected. The magnet, which is the detection target of the magnetic sensor, inherently has the direction of the magnetic poles with respect to the drive coil of the linear DC motor alternately along the moving direction of the moving body in order to drive the moving body, The magnetic sensor detects the magnetic field of the magnet in a non-contact manner. Therefore, the position information of the moving body can be obtained with high accuracy while having a simple configuration. Further, since detection is performed in a non-contact manner, there is no problem of dust generation unlike the related art.

[0005] The correction means provided in the position detecting means , based on the detection information of the gap sensor for detecting the gap between the magnetic sensor and the magnet, detects the signal of the magnetic sensor based on the standard signal between the magnetic sensor and the magnet. Correction is made so as to be a predetermined value corresponding to the interval. In other words, if the distance between the magnetic sensor and the magnet changes due to various factors, the detection signal will change even if the position of the moving body along the guide rail is constant, and the position information is correctly detected as it is. Although it may not be possible, it is possible to obtain a detection signal in a state where the distance between the magnetic sensor and the magnet always maintains the standard distance by the above-described correction processing. Can be detected with higher accuracy.

[0006] Further, by providing the configuration of the second aspect, the detection signal in which a plurality of magnetic sensor is detected, a phase difference corresponding to the distance in the moving direction of the moving body between the magnetic sensors each . Therefore, for example, if there is only one magnetic sensor, the moving direction of the moving body cannot be specified from the detection signal of the magnetic sensor, but the moving direction of the moving body can be determined by comparing the detection signals of a plurality of magnetic sensors. When trying to specify the position of the moving body within the range of the adjacent pair of magnets that can be specified, or the direction of the magnetic poles is alternated, the detection signal of the magnetic sensor should be substantially sinusoidal Therefore, if there is only one magnetic sensor, two positions correspond to the detection values of the magnetic sensor, and the position of the moving object cannot be uniquely specified. The position can be uniquely specified.

In addition, with the configuration according to the third aspect , the position detecting means detects the position of the moving body along the guide rail by integrating the wave number of the detection signal of the magnetic sensor. In other words, since the magnets for driving the moving body are generally arranged at a constant or almost constant pitch along the moving direction of the moving body, the directions of the magnetic poles are alternately arranged. The wave number of the detection signal of the magnetic sensor corresponds to the number of magnets arranged, and can be converted into a schematic position along the guide rail of the moving body. The above claim 4
With the configuration described above, the position detection unit can detect the presence range of the pair of magnets in which the directions of the magnetic poles are alternately determined based on the detection values of the plurality of magnetic sensors arranged side by side in the moving direction of the moving body. The position of the moving object is uniquely specified within the. From the position detected in this way and the position detected by integrating the wave number of the detection signal of the magnetic sensor, the position of the moving body along the guide rail can be converted with higher accuracy.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the transfer equipment using a linear motor according to the present invention is applied to a transfer equipment in a clean room will be described below with reference to the drawings. The transfer equipment shown in FIG. 2 is used for transporting luggage 14 such as semiconductor wafers in a clean room.
Is automatically transported, and the moving body A on which the load 14 is loaded is guided by the guide rail B, and moves between the stations ST provided along the guide rail B,
The package 14 is transported between the stations ST.

Hereinafter, the configuration of each part will be described. FIG.
As shown in FIG. 3, on the lower surface of the horizontal flange at the upper part of the guide rail B, there is provided a floating magnetic body 3 to which the magnetic force generating means 2 of the moving body A works. The magnetic force generating means 2
The magnetic force generating means 2 is attached to the lower frame 1 so as to be distributed and arranged at four places in front, rear, left and right of the moving body A, and each magnetic force generating means 2 includes a permanent magnet 2a and an electromagnet 2b. The electromagnet 2b is provided in a state where a pair of end faces of a U-shaped yoke are opposed to the magnetic body for levitation 3, and two coils wound around two bobbins externally fitted to the yoke are connected in series. . Further, a cylindrical permanent magnet 2a is arranged so as to cover each coil portion. That is, as shown in the plan view of FIG.
Yoke 2b _1, coils 2b _2, the permanent magnets 2a are arranged concentrically. A pair of permanent magnets 2a is mounted together with the frame 2a _1, the mounting structure to be described later,
It can be moved in a vertical direction (perpendicular to the plane of FIG. 4).

One of the pair of permanent magnets 2a is attached so that the end face (upper end) facing the magnetic body 3 for floating is an N pole and the lower end is an S pole, and the other end is an S pole at the upper end and an N pole at the lower end. It is attached to be a pole. Then, each of them generates a magnetic force (attraction force) with the magnetic material for floating 3. Flux electromagnet 2b occurs through a magnetic circuit comprising a pair of air gaps formed between the yoke 2b _1, levitating magnetic member 3, and, levitating magnetic member 3 and both end surfaces of the yoke 2b _1, electromagnets 2b A magnetic force is generated between the magnetic material and the floating magnetic body 3. However, when the direction of the magnetic flux generated by the electromagnet 2b is the same as the direction (polarity) of the magnetic flux generated by the permanent magnet 2a, the magnetic force of the permanent magnet 2a and the magnetic force of the electromagnet 2b reinforce each other. Weaken each other. Therefore, the electromagnet 2b (the coil 2
b ₂ ) Inverting the polarity of the exciting current and changing the strength of the exciting current change the attraction force acting between the magnetic force generating means 2 and the floating magnetic body 3 around the magnetic force by the permanent magnet 2a. Can be done. Further, the moving body A is provided with a control section C that controls the magnetic force of the magnetic force generating means 2 by controlling the exciting current of the electromagnet 2b, thereby controlling the moving body A to float with respect to the guide rail B. . The control of the exciting current of the electromagnet 2b by the control unit C will be described later.

A magnet 5 constituting the linear DC motor LM is provided at the bottom of the guide rail B, and a driving coil 6 constituting the linear DC motor LM together with the magnet 5 is supported on the lower frame 1 of the moving body A. It is provided via a member 6b. The length of one magnet 5 in the moving direction of the moving object A is about 30 mm, and as shown in FIG.
The magnets 5 are provided continuously over the entire length of the guide rail B so as to alternate with N, S, N.... Above the guide rail B, a power supply line 7 for generating a magnetic field when an alternating current is supplied is arranged in the longitudinal direction of the guide rail B, and power is supplied to the moving body A by the magnetic field formed by the power supply line 7. Is provided, and the power generated from the power receiving coil 8
And the driving coil 6 is supplied to the magnet 5
Cooperates with to generate a thrust for moving the moving body A,
While the moving object A is stopped, the moving object A is stopped and held. As shown in FIG. 3, the power receiving coil 8 includes a magnetic material 8a having an E-shaped vertical cross section and a primary coil 8b wound around a central projection of the magnetic material 8a. Are installed at positions covering the power supply line 7 and in a posture along the power supply line 7.

As shown in FIG. 5, a control unit C provided in the moving body A supplies an exciting current of the electromagnet 2b to the levitation driving circuit 1.
0, the position information of the moving body A is detected, and the power supplied to the drive coil 6 of the linear DC motor LM is controlled via the coil drive circuit 19 based on the position information. The traveling control of the moving body A is performed. Furthermore,
The control unit C communicates with the station ST,
The transmission and reception of information by optical communication is also performed via the communication unit 12. The information to be exchanged includes information on the traveling distance to the destination station ST, in addition to the identification number of the mobile unit A and the cargo information. First, levitation control by the control unit C will be described. Although omitted in FIG. 5, the floating drive circuit 10
Each of them is separately in charge of driving magnetic force generating means 2 (electromagnet 2b) provided at four positions in front, rear, left and right of the moving body A. The control unit C gives the information on the polarity and magnitude of the exciting current to the four levitation drive circuits 10 respectively. The output (excitation current) of each of the levitation drive circuits 10 is individually fed back to the control unit C via the current detection circuit 13.

The control section C controls the electromagnet 2b based on the detection information of the gap sensor 4 provided at the center of each magnetic force generating means 2 so that the gap between the moving body A and the guide rail B becomes a set interval. Controls the excitation current. Further, the set interval is changed according to the weight of the load, and control is performed based on the detection information of the current detection circuit 13 so that the steady value of the exciting current becomes zero. In other words, by controlling the exciting current of the electromagnet 2b in a small positive / negative range centered on zero, the magnetic force of the magnetic force generating means 2 is controlled by the electromagnet 2b centered on the magnetic force of the permanent magnet 2a.
By increasing or decreasing the magnetic force of the moving object A, the attractive force acting between the magnetic force generating means 2 and the floating magnetic body 3 is balanced with the gravity applied to the moving body A including the cargo. According to the above control, the heavier the load, the smaller the gap between the moving body A and the guide rail B becomes.
There is naturally a physical limitation in the adjustment range of the gap between the gap and the gap.
Therefore, in the magnetic levitation device of the present transport equipment, the relative position of the permanent magnet 2a and the electromagnet 2b in the perspective direction with respect to the levitation magnetic body 3 can be changed and adjusted. That is,
Based on the position of the electromagnet 2b, as the load becomes heavier, the attraction force acting between the permanent magnet 2a and the floating magnetic body 3 is increased by moving the permanent magnet 2a in a direction closer to the floating magnetic body 3. It is.

The configuration for this will be described.
As shown in FIG.
The mounting table 15 is attached to the lower frame 1 via the base 6 so that the mounting table 15 is lowered in the vertical direction while compressing the spring 16 according to the weight of the load 14. That is, luggage 14
Of the mounting table 15 and the restoring force of the spring 16 are balanced. At the lower end of the mounting table 15, a permanent magnet 2a (frame 2a ₁ ) is attached via a parallel link 17, and the mounting table 1
When 5 moves up and down, the permanent magnet 2a moves up and down by leverage. In addition, as shown in the plan view of FIG. 4, the lower end of the mounting table 15 is vertically rod-supported by the lower frame 1 so as to be vertically movable.
And a horizontal rod portion 15b extending leftward and rightward from the front end thereof. Parallel links 17 extending in the longitudinal direction at both end portions P of the horizontal rod portion 15b is pivotally connected to each other, the tip portion Q of each of the parallel links 17 frame 2a ₁ of the permanent magnet 2a is pivotally attached. An intermediate portion of the parallel link 17 is pivotally supported by a support member 18. Therefore,
When the mounting table 15 is lowered in the vertical direction, the horizontal rod portion 15b
The parallel link 17 acts as a lever with the pivot R with the support member 18 as a fulcrum, the power point as P, and the tip Q as an operating point, and the permanent magnet pivotally attached to the tip Q. 2a is moved upward. Thereby, the heavier the load, the more the permanent magnet 2a is moved in the direction approaching the magnetic material 3 for levitation. Further, by appropriately setting the spring coefficient of the spring 16, the relationship between the weight of the load and the movement amount can be set appropriately.

Next, the detection of the position information of the moving body A and the traveling control by the control section C will be described. Mobile A
Is provided with a magnetic sensor 9 extending from the rear end of the support member 6b of the driving coil 6 in order to detect positional information of the moving body A along the guide rail B.
The magnetic sensor 9 is composed of a front magnetic sensor 9a and a rear magnetic sensor 9b, which are arranged at intervals in the moving direction of the moving body A and are composed of a Hall element or the like. Since the detection signals of the front magnetic sensor 9a and the rear magnetic sensor 9b are provided at intervals as described above, as shown in FIG. 6, two substantially sinusoidal waves having a phase difference corresponding to the intervals are provided. Is obtained as

Front magnetic sensor 9a and rear magnetic sensor 9
The detection signal of b together with the detection signal of the gap sensor 4
The data is input to the correction data table 20 of the control unit C. The distance between the magnetic sensor 9 and the magnet 5 is, as described above,
Since it fluctuates under the control of the control unit C, even if the position of the moving body A along the guide rail B does not change, the detection signal of the magnetic sensor 9 may slightly change. The detection signal of the magnetic sensor 9 is corrected so as to be a detection value corresponding to a case where the magnetic sensor 9 and the magnet 5 are at a standard interval. The correction data table 20 is configured as a so-called lookup table, and outputs a detection signal corrected as described above using the detection signal of the front magnetic sensor 9a or the rear magnetic sensor 9b and the gap sensor 4 as address inputs. I do.
Accordingly, the correction data table 20 functions as a correction unit that corrects the detection signal of the magnetic sensor 9 to a predetermined value corresponding to the standard distance from the magnet 5,
The gap sensor 4 directly detects the distance between the gap sensor 4 and the magnetic material for levitation 3, but has substantially the same function as that of detecting the distance between the magnetic sensor 9 and the magnet 5. I do.

The data corrected for the front magnetic sensor 9a and the data corrected for the rear magnetic sensor 9b output from the correction data table 20 are separately input to the position specifying data table 21. As is apparent from FIG. 6, the guide rails B of the moving body A are determined based on the detected values of the front magnetic sensor 9a and the detected values of the rear magnetic sensor 9b at the same time within the range where the adjacent magnets 5 exist. Therefore, the position specifying data table 21 is also configured as a so-called lookup table, and the detection value of the front magnetic sensor 9a and the position of the rear magnetic sensor 9 are determined.
Using the detected value of b as an address input, position information within the existing range of a pair of adjacent magnets 5 is output. Therefore, the position data output from the position specifying data table 21 is a signal as shown in FIG. By using the position of the departure station ST as a reference position and integrating the output signal of the position identification data table 21 by the integration unit 22,
As shown in FIG. 8, the traveling distance from the reference position can be detected as the position information of the moving body A along the guide rail B.

The output of the position specifying data table 21 is also input to a forward / reverse determining unit 23, which compares the latest position data with the previous position data, and Is determined whether the vehicle is moving forward or backward, and is output to the integrating section 22. When the integration result increases even though the forward / reverse determination unit 23 determines that the vehicle is moving backward, the integration unit 22 performs a process of subtracting the distance for one cycle from the integration result. The position information expressed by the traveling distance from the reference position output from the integrating unit 22 is stored in the target traveling distance storage unit 25 and is stored in the departure station S.
The travel distance data from T to the destination station ST is input to the PID controller 24. here,
The mileage data stored in the target mileage storage unit 25 is the data received at the departure station ST. The PID controller 24 performs PID control of the coil drive circuit 19 based on the difference between these two inputs. However, the output of the PID controller 24 is limited so that the traveling speed and acceleration of the moving object A do not exceed the set values. Therefore, the control unit C functions as position information detecting means for detecting position information of the moving body A along the guide rail B based on the detection signal of the magnetic sensor 9.

[Other Embodiments] Hereinafter, other embodiments of the present invention will be listed. In the above-described embodiment, the case where the present invention is applied to a magnetic levitation type transfer facility is illustrated. However, a configuration in which the moving body A is provided with wheels and runs on the guide rail B on the ground may be used. In the above embodiment, the magnetic sensor 9 is constituted by two of the front magnetic sensor 9a and the rear magnetic sensor 9b, but the magnetic sensor 9 may be constituted by one or three or more.

In the above embodiment, the correction means for correcting the detection signal of the magnetic sensor 9 to have a predetermined value corresponding to the standard distance from the magnet 5 is configured as the correction data table 21. Alternatively, the correlation between the detection value of the magnetic sensor 9 and the correction amount for the detection value of the gap sensor 4 may be stored as an equation, and the correction may be performed using the relational equation .

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the structure shown in the accompanying drawings.

[Brief description of the drawings]

FIG. 1 is a side view of a moving body and a guide rail according to an embodiment of the present invention.

FIG. 2 is a layout diagram of the transport equipment according to the embodiment of the present invention.

FIG. 3 is an essential part cross-sectional view of the moving body according to the embodiment of the present invention, as viewed from the moving direction;

FIG. 4 is a plan view of the moving object according to the embodiment of the present invention;

FIG. 5 is a control block configuration diagram according to the embodiment of the present invention;

FIG. 6 is an explanatory diagram of position detection according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram of position detection according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram of position detection according to the embodiment of the present invention.

[Explanation of symbols]

 4 Gap sensor 5 Magnet 6 Driving coil 9 Magnetic sensor 20 Correcting means A Moving body B Guide rail C Position detecting means LM Linear DC motor

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60L 13/03 H02P 5/00

Claims (4)

(57) [Claims] 1. A driving coil (6) for a linear motor is provided on the moving body (A) side, and the driving coil (6) is provided on a guide rail (B) side for guiding the moving body (A). With linear DC motor (LM)
A linear motor provided in a state in which the magnets (5) are connected in such a manner that the directions of magnetic poles with respect to the driving coil (6) are alternately arranged along the moving direction of the moving body (A). A transfer facility for use, wherein a magnetic sensor (9) for detecting magnetism by the magnet (5) is provided on the moving body (A), and the moving body (A) is detected based on detection information of the magnetic sensor (9). interval of the position detection means for detecting the position information along the guide rail a) (B) (C), and said magnetic sensor (9) and said magnet (5)
And a gap sensor (4) for detecting the gap sensor, and the position sensor (C) is provided with the gap sensor (4).
The detection signal of the magnetic sensor (9) based on the detection information of
No. corresponds to the standard spacing with the magnet (5)
Correction means (20) for correcting to a predetermined value is provided.
Transport equipment of the linear motor use that is. 2. The moving body according to claim 1 , wherein
The transfer equipment using a linear motor according to claim 1, wherein a plurality of transfer equipment are arranged side by side at intervals in the moving direction of (A) . 3. The magnetic sensor according to claim 2 , wherein
By integrating the wave number of the detection signal of the sensor (9),
The position of the moving object (A) along the guide rail (B)
3. The transfer equipment using a linear motor according to claim 1, wherein the transfer equipment is configured to detect the transfer. 4. The apparatus according to claim 1, wherein said position detecting means (C) is operated at the same time.
The detected values of the plurality of magnetic sensors (9) are compared with each other.
By comparison, a set of magnets with alternating magnetic pole directions
Within the range of the net (5), the moving object (A)
It is configured to detect a position along the guide rail (B).
4. The transfer equipment using a linear motor according to claim 3 , wherein the transfer equipment uses a linear motor.