JPH04200286A - Signal detecting method in brushless dc linear motor - Google Patents

Abstract

PURPOSE:To permit the correct detection of the position of a movable piece and a speed signal by a method wherein the row of magnetic detecting element in a series, in which the direction of the flux of the permanent magnet of an operating polarity coincides with the direction of flux generated in a flat coil itself by the conduction of electric current, is selected in accordance with the moving direction of a linear motor to detect it as the position of the movable piece or the speed signal. CONSTITUTION:When a permanent magnet 22 approaches a Hall element 16a in the non-conducting condition of a flat coil 11 upon moving a movable piece 20 into a direction F, for example, the vertical component of flux on the Hall element 16a becomes equal to the vertical component of flux generated from the permanent magnet 22 because the flat coil 11 itself is in the non-conducting condition and flux is not generated. Accordingly, the Hall element 16a is made ON. Next, when the permanent magnet 22 approaches the Hall element 16b under the non-conducting condition under non-conducting condition of the flat coil 11, the vertical component of the flux on the Hall element 16b becomes equal to the vertical component of the flux from the permanent magnet 22. Accordingly, the Hall element 16b is made ON.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a signal detection method in a brushless DC linear motor.

"Prior art and its problems" Conventionally, in a moving magnet type linear motor, magnet position has been detected by a pair of magnetic detection elements 40, 41, as shown in FIGS. 4(a) and 4(b), for example. A movable element 42 that takes out a signal to the outside and moves it as shown by the broken line in the figure.
It was used as a position or speed signal. The magnetic detection elements 40, 41 are arranged at the centers of the front and rear winding portions 44a of a plurality of flat coils 44 arranged in a row as a stator, and are connected to a movable element 42 composed of a permanent magnet 45 and a yoke 46. It detects the magnet position. and,
The magnetic detection elements 40, 41 operate when the vertical magnetic flux density applied thereto becomes larger than a specific value BS.

However, the current flowing to the flat coil 44 as shown in FIG. 5(a)
On the illustrated X-ray when current is applied in one direction as shown in FIG.
), and at that time, the magnetic detection element 40.4
The value of magnetic flux on 1 is not 0, but is 0 at point 50
is located on the outer side of the magnetic detection element 40.41. A zero magnetic flux line 51 connecting the points where the magnetic flux becomes O on the flat coil 44 is shown by a two-dot chain line in FIG. 5(C). Therefore, in the case where there is a permanent magnet 45 on each magnetic detection element 40.4, each magnetic detection element 40.4
1, first, on the magnetic detection element 40 on the front side with respect to the moving direction F of the permanent magnet 45 shown in FIG. 6(a), the magnetic flux generated from the permanent magnet 45 and the direction F 1 in Fig. 4(a) in order to generate thrust. The vertical components B and Bc of the magnetic flux generated in the flat coil 44 itself due to the energization in the direction are in the same direction, and the magnetic detection element 40 due to the energization to the flat coil 44 is in the same direction.
Since the vertical component BT of the magnetic flux above has Bc added to BM, the magnetic detection element 40 operates stably. Next, see Figure 6 (
On the magnetic detection element 41 on the rear side with respect to the moving direction F of the permanent magnet 45 shown in b), the magnetic flux generated from the permanent magnet 45 and the I of FIG.
The respective vertical components B and BC of the magnetic flux generated in the flat coil 44 itself due to energization in two directions are in opposite directions,
The vertical component B of the magnetic flux on the magnetic detection element 41 due to energization of the flat coil 44 is 1B1=1B, 1-IBcl
Since B is less than the specific value Bs, the magnetic detection element 41 generates chattering. Therefore, since the magnet position detection signal from the magnetic detection element 41 on the rear side with respect to the moving direction of the movable element 42 is affected by chattering, there is a problem in that it becomes difficult to accurately detect the position or speed signal of the movable element 42. was there.

"Problems to be Solved by the Invention" The present invention was made to solve the above problems, and its purpose is to provide a brushless direct current that enables accurate detection of the position or speed signal of the movable element. An object of the present invention is to provide a signal detection method in a linear motor.

"Means for Solving the Problems" As shown in FIG. ), and a stator (10) having magnetic detection elements (16a, 16b) respectively disposed in the front and rear winding parts (lla, 1lb) in the longitudinal direction sandwiching the air core part of these flat coils (11), A movable element (20) is provided with a permanent magnet (22) arranged so as to correspond to the stator (10) from both sides, and the relative position of the flat coil (11) with respect to the permanent magnet (22) is adjusted as described above. In a movable magnet type brushless DC linear motor that detects with magnetic detection elements (16a, 16b) and switches the direction of energization to the flat coil (11) so that the movable element (20) moves in a fixed direction, the magnetic The detection elements (16a, 16b) are connected to the plurality of flat coils (11).
The system is divided into two systems, a front row and a rear row, and the direction of the magnetic flux generated in the flat coil (11) itself by energization matches the magnetic flux of the operating polarity permanent magnet (22) depending on the direction of movement. A signal detection method for a brushless DC linear motor is provided, which is characterized by selecting a magnetic detection element array of 1 and detecting its operation signal as a position or speed signal.

"Operation" In the signal detection method in the brushless DC linear motor configured as described above, magnetic detection elements (16a, 16
b) is separated into two systems, the front row and the rear row of flat coils (11), and the magnetic flux of the permanent magnet (22) of the operating polarity and the flat coil (11 ) selects a magnetic sensing element array whose direction of magnetic flux generated coincides with the magnetic sensing element array, so the operation signal of the selected magnetic sensing element array can be detected as an accurate position or speed signal of the movable element (20).

"Example" Embodiments of the present invention will be described with reference to the drawings.

The main feature of the signal detection method for a brushless DC linear motor of the present invention is that it enables accurate position or speed signal detection of a moving magnet type linear motor. As shown in FIG. 2, it is composed of a stator 10 and a movable element 20, which are arranged inside a guide rail 1. The guide rail 1 is a shaped material made of aluminum or the like, and is formed to have an approximately n-shaped cross section with an open bottom surface.

The stator 10 has flat coils 11 arranged in tandem in a number corresponding to the length of the guide rail 1. Each flat coil 11 is hermetically surrounded and held by fixing members 12 and 13 made of a shaped material such as aluminum, and a horizontal circuit board 14 is provided at the upper end to form a T-shape overall. On the circuit board 14, an electronic control circuit 15 is arranged for each flat coil 11, and predetermined connections are made as shown in FIG. Each flat coil 11 is also provided with a pair of Hall elements 16a, which are magnetic detection elements.
, 16b are arranged as shown in FIG.

The stator 10 configured in this way has the guide rail 1
The flat coil 11 is placed in the space of the guide rail 1, and the longitudinal part of the flat coil 11 is positioned in the center of the space of the guide rail 1.

The movable element 20 has a yoke formed in a substantially U-shape in cross section that also serves as a movable element body 21, and a plurality of permanent magnets 22, 22 are arranged in the longitudinal direction on the opposing inner surfaces thereof to form a magnetic circuit. The permanent magnets 22.22 that are adjacent to each other and those that face each other have opposite polarity, and the permanent magnets 22.22 that face each other have opposite polarities.
22 to form a -like magnetic field. Traveling rollers 31 are attached to both sides of the movable body 21 to allow the movable body 20 to move freely. The movable element 20 configured in this manner is inserted into the guide rail 1. At this time, the flat coil 11 of the stator 10 is located between the magnet gaps of the permanent magnets 22 and 22 that are arranged opposite to each other on the inner surface of the yoke. Furthermore, mover 20
The number of permanent magnets 22 arranged in is determined by the required thrust.

FIG. 2 shows the positional relationship and connection of a pair of Hall elements 15a and 16b arranged in the flat coil 11.

Each flat coil 11 has an air core section in the center of the front and rear coil winding parts 11a, llb with respect to the moving direction F of the movable element 20, and the flat coils 11 are arranged at a predetermined interval. Hall element 16a.

16b is arranged at the center position of the front and rear coil winding parts 11a and llb.

The detection signals of the Hall elements 16a and 16b are sent as external signals to n systems formed by connecting the rows of Hall elements 16a arranged in the front coil winding part 11a and to the rear coil winding part 11b. The arrays of Hall elements 16b arranged are separated into two systems of m systems formed by connecting them.

FIG. 3 is a schematic block diagram showing the overall configuration of this embodiment, and an electronic control circuit 15 is connected to the Hall elements 16a, 16b of each flat coil 11. The electronic control circuit 15 includes a transistor bridge 2 for controlling the direction of current flowing through the flat coil.
and direction selection switches 3 and 4. The flat coil current direction control transistor bridge 2 includes four transistors Tr, Tr2 . It is composed of Trs and Tr. The direction selection switches 3 and 4 are for switching the direction of current flowing to the flat coil 11, and the contact 3a of the direction selection switch 3 and the contact 4b of the direction selection switch 4 are connected to transistors Tr, Tr, and the direction selection switch The contact 3b of the direction selection switch 4 and the contact 4a of the direction selection switch 4 are connected to the transistor Tr2. Connected to Tr3. The section 3c side of the direction selection switch 3 is connected to the Hall element 16a, and the section 4c side of the direction selection switch 4 is connected to the Hall element 16b. The n system formed as shown in FIG. 2 is connected to the contact 5a side of the signal train changeover switch 5 which is interlocked with the direction selection switch 3.4, and the m system is connected to the contact 5b side of the signal train changeover switch 5. Ru. Intercept 5 of signal train selector switch 5
The c side is connected to a frequency-speed converter 6. The output of the frequency-speed converter 6 is sent to the current value controller 7 according to the target value. The current value controller 7 is supplied with power from a power supply circuit (not shown) and controls energization to the flat coil 11 based on the output of the frequency-speed converter 6 sent in accordance with a target value.

"Operation" The operation will be explained based on the above configuration.

In FIG. 2, when moving the movable element 20 in the direction F shown in the figure, the contacts 3a and 4a of the direction selection switch 3.4 are selected, and at the same time, the signal train changeover switch 5 is switched to the contact 5a. For example, when the flat coil 11 is in a de-energized state and the permanent magnet 22 approaches the Hall element 16a, the vertical component BT of the magnetic flux on the Hall element 16a is because the flat coil 11 itself does not generate magnetic flux in the de-energized state. It is equal to the vertical component BM of the magnetic flux generated from the permanent magnet 22. Therefore, BT becomes larger than the specific value Bs, and the Hall element 16a is turned on. Therefore, the transistors Try and Tr of the transistor bridge 2 for controlling the direction of current flowing through the coil are
4 is turned on, the flat coil 11 is energized from the power supply circuit through the current value controller 7 in the direction 11 in FIG. 2, and thrust in the F direction is generated in the mover 20 based on Fleming's left hand rule . When the flat coil 11 is energized, magnetic flux is generated in the flat coil 11 itself, and the vertical component Bc of the magnetic flux on the Hall element 16a is the vertical/directional component BM of the magnetic flux generated from the permanent magnet 22 on the Hall element 16a. The Hall element 16a operates stably.

Next, when the flat coil 11 is in a de-energized state and the permanent magnet 22 approaches the Hall element 16b, the eight vertical components of the magnetic flux on the Hall element 16b do not generate magnetic flux because the flat coil 11 itself is in a de-energized state. Therefore, it becomes equal to the vertical component BM of the magnetic flux generated from the permanent magnet 22. Therefore, B.T.
becomes larger than the specific value Bs, and the Hall element 16b turns on. Therefore, the transistor Tr2 of the transistor bridge 2 for controlling the coil current direction. Tr is turned on, and current is applied to the flat coil 11 from the power supply circuit via the current value controller 7 in the 12 directions shown in FIG. Therefore, a thrust force in the F direction is generated in the movable element 20 as in the case described above, and the movable element 20 continues to move in the same direction. When the flat coil 11 is energized, magnetic flux is generated in the flat coil 11 itself, and the vertical component Bc of the magnetic flux on the Hall element 16b is opposite to the vertical component BM of the magnetic flux generated from the permanent magnet 22 on the Hall element 16b. direction, and the Hall element 16
b causes chattering.

In this case, since the signal train selector switch 5 is switched to the contact 5a, the operation signal of the n-system Hall element 16a row, which is stable in operation, is detected as a speed signal, and is transmitted to the movable element 20 via the frequency-speed converter 6. The speed of is fed back to the current value controller 7.

Conversely, when moving the movable element 20 in the direction opposite to the F direction, the contact 3b of the direction selection switch 3.4.

4b side is selected, and at the same time, the signal train changeover switch 5 is switched to contact 5b.

Therefore, when the mover 20 moves in the F direction, the speed signal is always detected on the n-system side, and when the mover 20 moves in the opposite direction to the F direction, it is always detected on the m-system side. The movement speed of is accurately controlled according to the target value.

"Effects of the Invention" The present invention has the above configuration, separates the magnetic detection element into two systems of the front row and the rear row of a plurality of flat coils, and adjusts the operating polarity according to the direction of movement. The system selects a magnetic detection element array whose direction matches the magnetic flux of the permanent magnet and the magnetic flux generated in the flat coil itself due to energization, and detects the operation signal as a position or speed signal of the mover, so there is no chattering. Since the position or velocity signal of the movable element can be obtained, there is an excellent effect that the accurate position or velocity signal of the movable element can be detected.

[Brief explanation of the drawing]

Figures 1 to 3 show embodiments of the present invention, with Figure 1 being a sectional view of a movable magnet type linear motor, and Figure 2 being a diagram showing the positional relationship of the Hall elements and the connections for extracting their detection signals as external signals. The explanatory diagram shown in FIG. 3 is a schematic block diagram of the overall configuration, and FIG. 4(a). (b) is an explanatory diagram of the conventional method, Figures 5 (a) to (C) are explanatory diagrams showing the magnetic flux generated in the flat coil itself, and Figure 6 is an explanatory diagram of the magnetic flux generated from the permanent magnet and the magnetic flux generated in the flat coil itself. It is an explanatory diagram showing a relationship. 190. Guide rail, 10. ,, Stator, 11°, Flat coil, lla, llb, , Winding part, 16a,
16b, Hall element (magnetic detection element), 20,...
Mover, 22, 22. ,,permanent magnet. Figure 1 Figure 4 (a) Figure 5 Figure 6 (a) Figure 6 (b) 4 pieces

Claims (1)

[Scope of Claims] A fixing device having a plurality of flat coils arranged in the longitudinal direction in a space within a guide rail, and magnetic detection elements respectively disposed in the front and rear winding portions sandwiching the air core portions of these flat coils. and a movable element arranged so that permanent magnets correspond to the front and back sides of the stator, and the magnetic detection element detects the relative position of the flat coil to the permanent magnet, and the movable element is fixed at a constant position. In the movable magnet type brushless DC linear motor that switches the direction of energization to the flat coil so as to move in the direction, the magnetic detection element is separated into two systems, a front row and a rear row of the plurality of flat coils, and , depending on the direction of movement, select a magnetic detection element array whose polarity matches the magnetic flux of the operating polarity of the permanent magnet and the direction of the magnetic flux generated in the flat coil itself due to energization, and convert the operating signal to the position or speed signal of the mover. A signal detection method in a brushless DC linear motor characterized by detecting as follows.