JPH011466A - dc linear motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a DC linear motor, and particularly to a DC linear motor that directly drives a conveyor, a precision positioning table, etc.

[Prior Art] FIG. 24 is a diagram showing an example of a conventional DC linear motor in which a permanent magnet is used as a field and a conductor is wound in a distributed manner within a slot of an iron core.

First, the configuration of a conventional DC linear motor will be described with reference to FIG. 24. In the slots la, lb...1d, which are the winding spaces of the stator core 1, conductors 2a,
2b, 2c, etc. are the slots 1a, 1b...1d.
The coils are wound at a constant pitch to form a large number of excitation coils.

Note that FIG. 24 shows a state in which the conductor 2a straddles the slot 1a and the slot 1d.

A stator core 1 around which a conductor 2a and the like are wound is fixed on a fixed base 3 as a stator core assembly. A movable element (not shown) is arranged opposite to the stator core assembly by a linear guide that can freely move in the sliding direction, and the movable element is provided with a constant air gap 6a between the upper surface of the stator core assembly and the upper surface of the stator core assembly. , permanent magnets 4a and 4b for field are fixed on a magnetic circuit.

FIG. 25 is a diagram for explaining the operating principle of the DC linear motor shown in FIG. 24. Next, with reference to FIG. 25, the operating principle of a conventional DC linear motor will be explained. FIG. 25 shows only the relationship between the permanent magnets 4a, 4b and the conductor 2 in FIG. 24. Permanent magnet 4b
The magnetic flux emitted from the surface of the N pole passes from the air gap 6a in the direction shown by the arrow 7a, passes through the stator core (not shown) in the direction shown by the arrow 7b, and then passes through the yoke portion 1' of the core 1 shown in FIG. Proceed in the direction of 7c and pick up the permanent magnet 4a.
Arrow 7d points toward the south pole.

It advances in the direction of the arrow 7e within the air gap 6a and reaches the S pole of the permanent magnet 4a.

This magnetic flux further advances to the arrow 7f inside the yoke 5, flows into the N pole of the permanent magnet 4b, and forms a complete loop. At this time, if the current direction in the conductor is as shown in Figure 25,
The magnetic flux in the direction shown by arrow 7b interlinks with the conductor current flowing from the front side to the opposite side, and a force according to Fleming's left-hand rule acts on the conductor 2.

The direction of this force is to the left, but since the conductor 2 is fixed and the permanent magnets 4a and 4b are movable parts, the movable element generates a thrust that moves to the right according to a guide (not shown).

Furthermore, the magnetic flux and conductor current shown by arrow 7d (in FIG. 25, it flows from the opposite side to the near side).

) are interlinked, and according to Fleming's left-hand rule described above, a force is generated in the same direction as in the previous case, that is, a thrust is generated in the left direction on the conductor 2 and in the right direction on the mover, and the respective thrust forces are the sum. As a result, a rightward thrust is generated in the mover.

This is a method in which three phases of the conductor 2 are provided in the width of one pole of the permanent magnet 4a or 4b in the sliding direction, and two of these phases are energized to generate thrust.

FIG. 26 is a diagram showing an example of a drive circuit for the DC linear motor shown in FIGS. 24 and 25.

In FIG. 26, power transistors "II+T", 2.
. . . and the driving power source E are shown. The drive circuit is also provided with a detection section for detecting the position of the movable element and for making the power transistor "II+Tr12 conductive" and a logic circuit section, but the explanation will be simplified here. It has been omitted for the sake of.

In the example shown in FIG. 25, in order to generate a rightward thrust of the mover, the conductor ul+v+lu
21 v21 u31 va to conduct electricity, the power transistor Tr in FIG.

a+ Tr2. ,Tr,,,”2G+Tr,g.

This will turn on Tr27.

[Problems to be Solved by the Invention] In the above-mentioned conventional DC linear motor, thrust is generated by the magnetic flux and the energized conductor 2 interlinked with it, but the thrust is generated depending on the state of the magnetic flux and the positional relationship of the energized conductor 2. There is a drawback that the magnitude of the thrust varies.

This will be explained in more detail below.

FIGS. 27 to 31 are diagrams for explaining changes in thrust of a conventional DC linear motor. First, FIG. 27 shows the energization status of the conductor 2 and the positional relationship between the permanent magnet of the mover. In FIG. 27, the right end position of the movable element is point A, which indicates the position at the moment when the movable element moves from the left and switches to the illustrated energized state. Point B is the position just before switching to the next energized state, and point 0 is the position between points A and B.
This is the intermediate position between the point and the point. These A, B, C
Let's compare the magnitude of thrust from three points.

First, the relationship between the conductor 2 and the magnetic flux density distribution at point A is the 28th
The result will be as shown in the figure. That is, the magnetic flux distribution is generally smaller at both ends of the permanent magnet than at the magnetic center, resulting in a trapezoidal or nearly sinusoidal distribution as shown in FIG. At this point A, conductor u4. ■4. u2. The relationship between v2 and magnetic flux density B [T] is as shown in Figure 28.
, and u2 receive a strong magnetic flux and generate a large thrust, but
Conductors v1 and ■2 have weaker magnetic flux distribution than conductor Ul+ u2, so the thrust is weaker.0On the other hand,
When the mover moves and reaches the 0 point shown in Fig. 27, the relationship between the magnetic flux distribution and the conductor 2 is as shown in Fig. 29,
Both conductors 11 + vI +1□+ (2) are subjected to strong magnetic flux.

Therefore, the thrust at the 0 point shown in FIG.
It is clear that a larger force is generated than the thrust at point A shown in the figure. Furthermore, the mover advances and the second
The thrust when reaching point B in FIG. 7 is the same magnitude as at point A, as shown in FIG. 30. In this way, while the mover moves from point A to point C to point B, fluctuations in thrust occur. In this state, as shown in Fig. 31,
The magnitude of thrust F [kgf] increases as the mover moves,
Because of the wave-like fluctuations, linear motion may not be smooth or may cause vibrations.

Moreover, as shown in FIG. 27, the conductor 2 has three phases (u I
+ vl * Wl, etc.), but the conductors 2 that are energized are only for two phases (u+, vl),
The magnetic flux generated by the permanent magnet is not effectively converted into thrust, resulting in waste.

FIG. 32 and FIG. 33 are diagrams for explaining the thrust at both ends of the stator core. FIG. 32 shows an example of the rightmost stator core assembly and mover in the sliding direction of the DC linear motor, and the number of conductors 2 generating thrust is slot SII S2+ 8
There are 8 conductors in 4+85. However, this conductor 2 and permanent magnet 4a.

4b, the conductor of the slot S++ 54 is out of the N-pole and S-pole regions of the permanent magnets 4a and 4b, so that the conductor is switched to the energized state as shown in FIG. 33.

The number of conductors 2 at this time is the slot s2. s3+
"There are 7 wires in S-sG, and the thrust is reduced to 87.5% compared to the normal 8 wires.Furthermore, when the mover moves to the right and the energization state is switched, the conductor 2 becomes 6, and the thrust decreases to 75%.In other words, the 3rd
In the length addition at the right end shown in Figure 3, the thrust decreases and becomes an invalid length. This invalid length stop is also on the left end, and 2Q of the total length
, which has the disadvantage that it becomes an inactive component or a region of reduced thrust.

Note that the length corresponds to the length of one pole of the magnet.

FIG. 34 is a sectional view taken along line A-A' shown in FIG. 24.

In FIG. 34, since the conductor 2 is wound across two slots, the conductor 2 is wound on the left and right sides of the stator core 1.
Protruding portions 2', 2' are generated. These protruding portions 2', 2' occupy a considerable amount of space and become a factor in increasing the width of the DC linear motor. This protruding portion 2'.

The amount of conductor 2' corresponds to the amount of conductor 2a, 2b, and 2c in the cross section along line AA' shown in FIG.
It is approximately equal to the amount stored in the slot.

In addition, in a conventional DC linear motor, as shown in Figure 26, conductors for three phases are required for one pole pitch of the permanent magnet, so two power transistors are required for each conductor. , the number of power transistors is extremely large. Moreover, since six power transistors are always required in the drive circuit, there is a drawback that the position detector for controlling the transistors and the logic circuit for turning on the power transistors using the position detection signal are extremely complicated.

The position detector is the same as in the case of a rotary three-phase brushless DC motor, with permanent magnets 4a and 4 for one pole each of N and S.
Three pieces are required at three equal pitches between one pair of poles b. For example, the stator length is 500mm.

If the pitch of one permanent magnet pole is 25 mm, three position detectors are required for a 50 mm stator, and 30 position detectors are required for the entire length.

FIGS. 35 to 37 are diagrams showing a method of compensating for a decrease in thrust in a conventional DC linear motor. The second mentioned above
The DC linear motor shown in Figure 4 is a 2-pole, 3-phase unipolar system, but as a means to further increase the capacity, the width of the permanent magnets has been widened, as shown in Figure 35. This is an example.

In the example shown in FIG. 35, the width of the permanent magnets 4a and 4b shown in FIG. 24 is doubled, and the conductor 2 is arranged in series for two slots.

Therefore, the drive circuit may be configured to be similar to that shown in FIG. 26, but as described above, the length of the portion where the thrust decreases at both left and right ends is doubled. There are drawbacks. Moreover, the line A- shown in FIG.
The amount of conductor protruding from the stator core in the cross section along A' is also twice that in the cross section along line A-A' shown in FIG. That is, the amount of protruding portions 2', 2' of the conductor shown in FIG. 34 is doubled, resulting in a disadvantage that the width of the linear motor becomes even larger.

Furthermore, as another means to compensate for the decrease in thrust, there is a method of increasing the number of poles of the permanent magnet. The example shown in Figure 36 is 4
The current-carrying conductor is uI+ v++
u2+ V2+ ua, v,, u4+
There are 10 conductors of V4 + uS + vS.

In order to drive such a conductor, the drive circuit is
It is necessary to configure as shown in the figure, and the power transistors that are conductive at the same time are Tri a + Tra I +
Tr I 4 1 Tr a s
+ T r + g, T
r 3 7 r T r 20 , Tr
, 2, Tr25, and Tr43, resulting in a further disadvantage that the drive circuit becomes complicated.

Therefore, the main object of the present invention is to provide a DC linear motor which can eliminate the above-mentioned drawbacks and which exhibits extremely little reduction in thrust.

[Means for Solving the Problems] The present invention provides a DC linear motor including a stator core around which a conductor is wound, and a field permanent magnet arranged opposite to the stator core and serving as a mover. A coil is constructed by winding a conductor in a ring shape between the field permanent magnets and the back side of the stator core. Coils with the same number of turns per unit length in the sliding direction are electrically connected to form a coil group. A conductor is arranged so that current flows in the same direction through a plurality of continuous coil groups that are longer than the length of one pole of a permanent magnet, and is energized over a section that is sufficiently long than the length of a pole of a field permanent magnet. It consists of

More preferably, the distance between the poles of the field permanent magnet is selected to be twice the pitch of the coil group.

Further, the stator core is made of formed and laminated electromagnetic steel plates, the length of which is selected to be an integral multiple of the length of the coil group, and a predetermined number of stator cores are arranged in a sliding direction by magnetically continuous means.

Further, the stator core may be formed by laminating a plurality of square pieces of soft iron to have a predetermined size, or may be formed by a single square piece of soft iron having a predetermined size.

As an example, two sets of stator cores are provided so that each stator core is arranged in the center, and each field permanent magnet is opposed to the two sets of stator cores, and the polarity of each is different and the current direction of the opposing conductor is set. Each coil group is electrically connected so that the coils are in the same direction. Further, as another example of the stator core, the stator core is provided in the center, and two sets of field permanent magnets are provided on both sides of the stator core so that they face each other and have the same polarity.

Furthermore, adjacent coil groups are electrically connected to each other in series, and coil groups at both left and right ends are also electrically connected to each other, and the current flowing through each coil group is switched by a semiconductor element.

Furthermore, the position detection elements are arranged so as to have an interval twice the coil group pitch, and three times the coil group pitch.
A target with double length is attached to the mover.

Furthermore, the semiconductor element is controlled by the logic circuit based on three signals: the signals from two adjacent position detection elements and the OR signal of the signals on both sides.

[Function] The DC linear motor according to the present invention has a coil formed by winding a conductor in a ring shape between the stator core and the field permanent magnets and over the back surface of the stator core.
Since energized conductors exist in all sections of the magnetic flux distribution, a large thrust can be obtained.

[Embodiments of the Invention] Fig. 1 is a diagram showing the structure of an embodiment of the present invention, and Figs. 2 and 3 are diagrams showing the shape of a stator core included in an embodiment of the invention. FIG. 4 is a diagram showing the arrangement relationship between a position detector and a target, and FIGS. 5 and 6A are diagrams showing an example of a drive circuit.

First, the configuration of an embodiment of the present invention will be described with reference to FIGS. 1 to 6A. In FIG. 1, a stator core 10 is constructed by laminating formed electromagnetic steel sheets to a predetermined thickness. This stator core 10 is provided with teeth 10a as a magnetic circuit, slots 10b as a winding space, a yoke 10e as a magnetic circuit, and a winding space 10c on the back side.
A leg 10f for attachment to the attachment member 30 is included.

The stator core 10, especially for long linear motors, is constructed in the shape shown in FIG. As shown in Figure 3, several sheets are stacked one on top of the other and then placed on the front.

By overlapping them in the order of back, front, etc., unevenness is formed on both left and right ends, and by abutting these in the sliding direction, a completely magnetically continuous stator core is formed.

The conductor 20 is wound in a ring shape around the yoke 10e in the slot 10b and the winding space 10c on the back side. In Figure 1, two conductors are connected to one slot.
Although one 0 is shown, there are actually multiple windings. This conductor 20 is electrically connected in series between the conductors of adjacent slots, and the coil group CI+c2. ...Cf is formed. In the example shown in FIG. 1, five slot groups are used as one coil group.

The stator core assembly in which the conductors 20 are wound around all the slots as described above is fixed to the mounting member 30 by the legs 10f of the stator core.

On the other hand, the mover is arranged so as to be able to freely move left and right by a linear guide (not shown), and permanent magnets 40a and 40b, which are the field of the near motor, are attached to the mover and maintain an air gap 60a with the surface of the stator core assembly. Moreover, a magnetic circuit fixed to the yoke 50 is attached.

The permanent magnets 40a and 40b have opposite poles facing the stator core assembly. The permanent magnets 40a, 40
The spacing between the respective magnetic centers of b in the sliding direction is arranged to be three times the pitch of the coil group. That is, the permanent magnet 40a.

40b with a space of two coil group pitches. The coil groups are all electrically connected in series with each other, and a tap is taken out from the connection part,
This tap becomes the lead wire of the stator core.

This lead wire is connected to the positive side power transistor Tr of the drive power source E in the drive circuit shown in FIG.

Tra, Trl... and negative side power transistor Tr
2. They are all connected in order to the connection points of Tr, Trg, . . . . The lead wires at both ends are connected and short-circuited by a shorting wire 100, and the coil group is electrically looped.

Power transistors Tr, Tr, of the drive circuit shown in FIG. is driven by the position detector shown in FIG. That is, the target 80 fixed to the mover
The length in the sliding direction is 3 coil pitches (in Fig. 4, the pitch of one coil group is 11, c, so the length of the target 80 is 31c), and the detection ropes a to g are attached to the fixed part. They are arranged at equal intervals, and the interval is the pitch of two coil groups, that is, the length of 21c.

The control circuit shown in FIG. 6A uses the power transistor T shown in FIG. 5 based on the signal from the position detector shown in FIG.
It is composed of a logic circuit that drives r, to Tr, (,
It is composed of an OR circuit 101, an EXOR circuit 102, an 8-channel multiplexer 103, and a drive circuit 90. The OR circuit 101 is for calculating the logical sum of two skipped signals, such as a and d, b and e, etc., among the signals of the position detector. The 8-channel multiplexer 103 is an exclusive OR circuit that inverts the output of the movable element, and the 8-channel multiplexer 103 transfers the position detection signal to each of the power transistors Tr+ to Tr included in the drive circuit 90 corresponding to the position of the movable element.

. It outputs a signal to conduct the ◎7th
The figure is a diagram for explaining the operation of an embodiment of the present invention, FIGS. 8 and 9 are diagrams for explaining the operation of the drive circuit, and FIG. 10 is a diagram for explaining the operation of the drive circuit. 11 is a diagram showing the operation logic of the 8-channel multiplexer, and FIG. 12 is a diagram for explaining the operation of the control circuit shown in FIG. 6A.

Next, with reference to FIGS. 7 to 2, a specific operation of an embodiment of the present invention will be described.

The operation explanatory diagram shown in FIG. 7 is based on the permanent magnet 4 in FIG.
0a, 40b and the conductor 20, the magnetic flux generated from the surface of the permanent magnet 40b moves through the air gap 60a with the stator core (not shown) by the arrow 7-O.
a, and flows through stator core teeth 10a, 10e in the direction of arrow 70b. Here, the magnetic flux flowing in the direction of arrow 70e is minute because it is outside the stator core yoke, and all the magnetic flux flows in the direction of arrow 70b. Further, the magnetic flux passes through the lower teeth of the S pole of the permanent magnet 40a, flows through the air gap 60a in the direction of the arrow 70c, reaches the S pole of the permanent magnet 40a, and further flows through the yoke 50 as indicated by the arrow 70c.
It flows in the direction of 0d, reaches the permanent magnet 40b, and forms a loop.

On the other hand, the conductor 20 has a coil group c as shown in FIG.
When a current is applied to I+'2 and c4+CI in the direction shown in the figure, in the positional relationship between the permanent magnets 40a, 40b and the conductor 20 shown in FIG. c4 and generates thrust here. Such an energized state is established by the drive circuit shown in FIG. 5 to control the power transistors Tr+, Tr23 . Tr+
This is possible by making the four transistors G and Tr24 conductive.

This state is maintained until point B shown in Fig. 7, and when reaching point B where thrust is being generated, the energization state is switched and
Advance in the 1st coil group pitch direction (to the right). In this state, the power transistor 'rr, 2 shown in FIG.
．． Tr24, Tr, and Tr2. is achieved by becoming conductive. In this way, by advancing the magnetic field caused by the conductor current in the traveling direction, the linear motor continues to generate effective thrust.

Next, switching of energization to the conductor is performed based on the output signal of the position detection device shown in FIG. FIG. 4 (In the position detection device shown in FIG.
- Since the spacing between g is at a ratio of 1.5:1, one or two movable elements of the detector are operating at any position.

Specifically, the target 80 and detector a shown in FIG.
, b...G, a and b are operating, but if the target 80 moves to the right by one coil pitch, only b is activated, then b and C... and so on. It turns out. The drive circuit shown in FIG. 6A processes each detection signal and makes a predetermined power transistor T', or Tr, conductive.

The output signals of the position detectors a to g are applied to the inputs of the drive circuit shown in FIG. 6A, and the output signals of the drive circuit are supplied to the power transistors Tr1 to Tr shown in FIG. given to. The OR circuit 101 of the drive circuit connects position detectors a and b.
・・・It calculates the logical sum of every two signals among the signals from position detectors a and d, b and e,
The logical sum of the signals c and f... is formed. In the example shown in FIG. 6A, the original signal is transmitted to the position detector a,
Since there are seven outputs of b...g and a total of seven OR signals, a total of 14 signals are obtained.

EXOR circuit 102 calculates the exclusive OR of these OR signals. This is necessary to determine the direction of the linear motor, and one of the inputs of the EXOR circuit 102 can be switched to either "H2" or "L# level" by the switch 105. In the example shown in FIG. 6A, when switch 105 is off, E
One input of the XOR circuit 102 becomes “H” level,
The output signal of the position detector a-H is output from this EXOR circuit 10.
2 will be inverted.

Furthermore, if the switch 105 is on, the EXOR circuit 1
One input of 02 becomes "L" level, and the output signals of position detectors a-H are output as they are.

In this way, the signal passing through the EXOR circuit 102 is 8
is applied to channel multiplexer 103. This 8-channel multiplexer 103 has 3 channels and outputs 8 channels, and the IC as shown in FIG.
Consisted of. The operating logic of this multiplexer 103 is as shown in FIG. 11. For example, when "L", "H", and "L" are manually applied to each channel of C9B and A, a signal is output from the second channel.

In the control circuit of FIG. 6A, the inputs to the multiplexer 103 are the output signals of two channel groups of adjacent position detecting devices and the OR signal of the two channel groups before and after the output signals.

For example, the ICI is manually inputted with three signals: a logical sum of the output signal of the position detector a and the output signal of the position detector d; one output signal of the position detector A; and the output signal of the position detector C. To be more specific, in FIG. 4, the position signals of the output of the position detector a and the output of the position detector S are at "H" level. Therefore, a
The logical sum output of d, b+e, e+a and f+b is also “H”.
” level.Here, the thrust in the right direction is the positive direction,
When the switch 105 is turned on and the above-mentioned signal is not inverted, ICI or I of the multiplexer 103 is
The input state of C7 is as shown in FIG. 12 (I).

Therefore, the ■ channel of ICI and the ■ channel of IC6 become valid output signals, and the power transistor TrB,
Tr44. Tr and Tr6 become conductive. In this state, a current flows in the direction of the arrow shown by the solid line in FIG. 8, and the conductors are energized in the CI-'C2 and Cs-c4 directions, generating a rightward thrust. When the movable element advances by one coil pitch, only the output signal of the position detector becomes "H" level.

At this time, b+e and f+b also become "H" level, and the input states to multiplexers ICI to IC7 become as shown in (II) of FIG.

Here, only the ■channel of IC1 and the ■channel of IC7 become valid output signals, and the power transistor T
r, o, Trl 3 r Tr, and Tr 6
conducts, and current flows in the direction of the arrow shown by the dotted line in FIG. Current flows in the conductor in the C2->C3, C6-C5 direction. In this case, compared to the above-mentioned state (1), the energization to the coil group is advanced by one pitch in the right direction.

Here, in order to reverse and generate thrust to the left,
When the switch SW is turned off, all position signals are inverted, resulting in a state as shown in FIG. 12(m).

At this time, the ■channel of IC1 and the ■channel of IC7 become effective, and the power transistors Trg and Tr+
a + Tr4 and Tr7 are conductive, and the conductors are C, -
e(2, C, -4 The current is switched to the direction of IC5, a thrust is generated in the left direction, and the rotation is reliably reversed.

In the operating state described above, the current flowing through each conductive power transistor is uniform, and when the electromagnetic field passing through the conductor is progressing continuously to the left and the mover is also moving in one direction, the current flowing through the conductor suddenly changes. The direction of the current is reversed, and the characteristics are not adversely affected.

In the above embodiment, the distance between the permanent magnets 40a and 40b is two coil pitches, but if this is set to one coil pitch, as shown in FIG. 9, the conductor is energized at position C. -C2,C4→C1, power transistor T "+-eTr,2,"rr,-*T
r, the state becomes energized in two directions. Here, since the power transistors Tr and □ are bidirectional current circuits, twice as much current flows through the power transistors Tr+ and TrB. Next, the magnetic field advances and conductors C2→C8,
Also in the case of C1→c4, the power transistor Tr+,
Because twice as much current flows through , it is necessary to increase the capacity of the power transistor, and the direction of the conductor current is also unfavorable because in this example, the coil group of C8 suddenly reverses.
It is preferable that the N and S pole permanent magnets 40a and 40b are arranged at intervals of the coil pitch group.

Next, another example of the drive circuit will be described with reference to FIG. 6B. The drive circuit shown in FIG. 6B inputs a total of eight signals, seven signals given from the position detector and a direction signal, to the ROMs 201 to 204.
Based on data prestored in 204, 20 power transistors Tr, ~Tr,. It is driven by switching sequentially.

FIG. 13 shows the magnetic flux density B [T] of the coil group and N-pole permanent magnet 40b when the mover is in position A in FIG.
FIG. 14 shows the same relationship as FIG. 13 when the movable element is at position B in FIG. 7, and FIG. 15 shows the relationship between the position of the movable element and the generated thrust F. It is.

When moving to the right while the conductor is energized as shown in Fig. 13, from the initial position to the position indicated by the dotted line C in Fig. 13 and then to the position shown in Fig. 14, the magnetic flux density B between these positions is
The relationship between the distribution and the energization state is uniform. Further, the generated thrust has no longer fluctuated as shown in FIG. That is, as is clear from FIGS. 13 and 14, there is a conductor that is energized throughout the entire range of magnetic flux distribution. On the other hand, in the conventional examples shown in FIGS. 27 to 31 described above, there is a non-current conductor within the section of the magnetic flux distribution and it does not contribute to the thrust, but in the embodiment of the present invention Since the relationship between the distribution of magnetic flux density B and the current-carrying conductor becomes uniform, a large thrust force can be obtained.

FIG. 16 is a diagram showing the relationship between the stator core assembly at the right end of the beam near motor and the permanent magnet, and FIG.
It is a sectional view along line BB' in a figure.

As shown in FIG. 16, in one embodiment of the present invention, the number of current-carrying conductors 20 does not change whether at the rightmost end or at an intermediate position, and there is no waste at both left and right ends of the stator core assembly, and all of them are effective. becomes. Moreover, the cross section of the stator core assembly part is as shown in Fig. 17.
Unlike the conventional winding method, many conductors do not intersect in the cross section, so the only part protruding from the stator core (coil end) is the conductor bone housed in one slot, as shown in Figure 34 above. In addition, in the drive circuit according to an embodiment of the present invention, the power can be reduced by making the length LE + smaller than the length LE2, and the width of the linear motor section can be made smaller. If the number of transistors is defined as the pitch of one coil group - the width of one pole of a permanent magnet, only two power transistors are required for the width of one pole of a permanent magnet, which is significantly larger than the conventional method that requires six. The number of power transistors can be reduced.

Since the number of these power transistors can be significantly reduced, the control circuit that controls them can also be simplified.

Further, in one embodiment of the present invention, it is sufficient to provide one position detection device at the pitch of two coil groups, and the stator length is 500 mm and the pitch of one permanent magnet pole is 25 mm.
, assuming that the pitch of one coil group is 25 mm, it is sufficient to arrange 20 position detectors in total length, and the number of position detectors can be reduced to 2/3 compared to the conventional example.

FIG. 18 is a diagram for explaining a method of increasing thrust in an embodiment of the present invention, and FIG. 19 is a diagram showing an example of the drive circuit of FIG. 18.

In an embodiment of the present invention, if the thrust is to be doubled, permanent magnets 41a and 41b with twice the width (pitch) of permanent magnets 40a and 40b shown in FIG. 1 may be provided. . The space between the two poles of these permanent magnets 41a and 41b may be the same as in FIG. 1, with a pitch of two coil groups. Furthermore, the stator core assembly is completely unchanged from that shown in FIG. In addition, in Fig. 18,
One coil group is collectively shown as one conductor.

A drive circuit for driving such a conductor may be constructed as shown in FIG. 19, and the example shown in FIG. 19 is no different from the above-mentioned FIGS. 5 and 8. However, only the position of the conductive power transistor needs to be changed, and only the wiring method of the circuit needs to be changed so that the three coil groups are energized in series. Therefore, the thrust force can be increased freely without increasing the number of coil ends and complicating the control circuit, which were the drawbacks of the conventional method.

Note that the width of the permanent magnets 41a and 41b may be made three times or four times that of the permanent magnets 40a and 40b shown in FIG. In addition, in the drive circuit shown in FIG. 5, the lead wires at both left and right ends are short-circuited by the short-circuit wire 100 to form a loop, so that the power transistors Tra l , Tr, which are necessary for energizing the coil group cps in FIG. □ (dotted line portion in FIG. 5) is not required, and the coil group CI5 can be energized by the power transistor Tr, 1 or Tr2, and the number of power transistors can be omitted.

In the above embodiment, as shown in FIGS. 2 and 3, the stator core can be manufactured in a certain unit length, and the stator core assembly can be made by winding the conductor in units of that length. Even such a long linear motor can be easily manufactured by simply adding the stator core assembly described above.

By the way, in DC linear motors using permanent magnets such as the conventional example and the above-described embodiments, the magnetic attraction force of the permanent magnets may become a problem. That is, in the DC linear motor shown in FIG. 1, the permanent magnets 40a and 40
b constitutes a magnetic circuit, facing the stator core 10 via an air gap 60a. In such a magnetic circuit, the magnetic attraction force acts in a direction that reduces the air gap 60a. In other words, the permanent magnets 40a, 40b and the yoke 50 are pulled downward with a considerably strong force.

This puts a strain on the linear guide and increases sliding resistance, which can lead to increased thrust loss (mechanical loss), reduced guide durability, and reduced accuracy in precision linear tables. Become. Therefore, an embodiment that can prevent such a phenomenon will be described.

FIG. 20A is a diagram showing the configuration of another embodiment of the present invention, and FIG. 21 is a diagram showing an example of the drive circuit of FIG. 20A. In the embodiment shown in FIG. 20A, a yoke 50 is arranged in the center, and permanent magnets 40a, 40b, 40 are arranged on both sides of the yoke 50.
a', 40b', and the stator core assembly 10 is arranged relative to the permanent magnets 40a, 40b, the permanent magnet 40a'.

stator core assembly 10 opposite to 40b'
′ is arranged. Note that the yoke 50 as a movable element can be made thinner than the conventional example.

This consists of permanent magnets 40a and 4 facing each other as shown in Figure 20A.
By making the surface polarities of 0b' different, the magnetic flux is distributed between the S pole of the permanent magnet 40a - the N pole of the permanent magnet 40b - the permanent magnet 4
It flows in the path from the S pole of 0b' to the N pole of permanent magnet 40a',
This is because almost no water flows into the yoke 50. Furthermore, by energizing the opposing coil groups of the stator core assemblies 10 and 10' in the same direction, thrust is generated in the same direction. In addition, the drive circuit is the 21st
The circuit will look like the one shown in the figure. That is, by connecting the opposing coil groups C1 to Cs and c, L to C6' in series with the same polarity, the number of power transistors can be reduced to 1.
The position detection device, the drive circuit, and the control circuit are all
The same thing as shown in the figure can be used and exactly the same effect can be obtained.

FIG. 20B is a diagram showing the configuration of another embodiment of the present invention. In the embodiment shown in FIG. 20B, the stator core assembly 10 is arranged in the center, and the permanent magnets 40a and 40b and the yoke 50 are arranged on one side, and the permanent magnets 40a' and 40b' and the yoke 50 are arranged on the other side. ′ is arranged.

In addition, according to this embodiment, compared to the embodiment shown in FIG. 20A described above, copper loss is reduced and efficiency can be improved.

In the embodiment shown in FIG. 20A, this is the annular coil group C of stator core assemblies 10 and 10'.
1, C2...+CI'+02'..., the part that contributes to thrust generation is the central permanent magnet 4.
0a, 40b, 40a', 40b', and in the embodiment shown in FIG.
Permanent magnets 40a, 40b, 40a' on both sides of 2...
, 40b' face each other, and both sides of the coil groups C7, C2, . . . contribute to thrust generation. In addition, permanent magnet 4
0b and 40b' are N poles, and permanent magnets 40a and 40a'
By setting this as the south pole, the magnetic flux flows as shown by arrow 7.

Further, if the coil group CI l C21C41Cg is energized as shown in the figure, thrust will be generated in both yokes 50 and 50' in the right direction as shown in FIG. 20B. Moreover, the same drive circuit as shown in FIG. 5 can be used, and exactly the same effect can be obtained.

FIG. 22 is a diagram showing another embodiment of the present invention,
FIG. 23 is a sectional view taken along line c-c' in FIG. 22.

In the embodiment shown in FIG. 22, the stator core 10 is constructed by stacking electromagnetic steel plates in the form of strips to a predetermined thickness, and a conductor 20 is wound around this in a ring shape, so that the stator core 10 is formed into rectangular strips. Pull out the taps for each length, and connect the coils between the taps to the coil group C+ l
. . . collectively constitute the stator core assembly. Other than that, the arrangement of the permanent magnets, the drive circuit, etc. are exactly the same as in the previous embodiment. By configuring the stator core assembly 10 in this way, when the magnetic flux density is low or when the core loss is small at low speeds, a square piece of soft iron may be used as is. Further, the stator core assembly configured in this manner can also be applied to the embodiment shown in FIG. 20A described above.

[Effects of the Invention] As described above, according to the present invention, by forming a coil by winding a conductor in a ring shape between the stator core and the field permanent magnets and over the back surface of the stator core,
The relationship between the magnetic flux density distribution and the current-carrying conductor can be made uniform, and fluctuations in the generated thrust can be reduced.

Moreover, there are energized conductors in the entire section of the magnetic flux distribution.
Therefore, a larger thrust force can be obtained compared to the conventional example. Furthermore, since the number of current-carrying conductors does not change either at both ends of the stator core or at an intermediate position, there is no waste and all the conductors can be used effectively. Furthermore, since a large number of conductors do not cross the cross section of the stator core as in the conventional case, the portion protruding from the core can be reduced, and the width can be reduced. Furthermore, the number of semiconductor elements for driving the conductors can be reduced, and the control circuit for controlling them can also be simplified.

Further, by providing two sets of stator cores and arranging field permanent magnets to face these stator cores, mechanical loss can be reduced and accuracy can be improved.

Further, by providing the stator core in the center and providing two sets of field permanent magnets facing each other on both sides of the stator core, it is possible to reduce copper loss and improve accuracy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of an embodiment of the present invention. FIGS. 2 and 3 are diagrams showing the shape of the stator core. FIG. 4 is a layout diagram of a position detector in an embodiment of the present invention. FIG. 5 is a diagram showing a drive circuit included in one embodiment of the present invention. FIG. 6A is an electrical circuit diagram of a control circuit included in one embodiment of the present invention. FIG. 6B is an electric circuit diagram showing another example of the control circuit. FIG. 7 is a diagram for explaining the operation of one embodiment of the present invention. FIGS. 8 and 9 are diagrams for explaining the operation of the drive circuit according to an embodiment of the present invention. FIG. 10 is a diagram showing an 8-channel multiplexer included in the control circuit. FIG. 11 is a diagram showing the logical operation of the multiplexer. FIG. 12 is a diagram for explaining the operation of the control circuit. FIGS. 13 to 15 are diagrams for explaining the thrust generated in one embodiment of the present invention. FIG. 16 is a diagram for explaining the thrust at both ends of the stator core. FIG. 17 is a diagram showing the size of the coil end of the stator core. FIG. 18 is a diagram for explaining a method of increasing the thrust of an embodiment of the present invention. FIG. 19 is an electric circuit diagram showing a drive circuit for increasing the thrust and driving the near motor. FIGS. 20A and 20B are diagrams showing the structure of another embodiment of the present invention. FIG. 21 is an electrical circuit diagram of the driving circuit of the embodiment shown in FIG. 20A. FIG. 22 is a diagram showing the structure of another embodiment of the invention. FIG. 23 is a sectional view taken along line c-c' in FIG. 22. Second
FIG. 4 is a diagram showing the structure of a conventional linear motor. Second
FIG. 5 is a diagram for explaining the operation of a conventional linear motor. FIG. 26 is an electrical circuit diagram of a drive circuit for a conventional linear motor. FIGS. 27 to 31 are diagrams for explaining thrust fluctuations in a conventional linear motor. FIGS. 32 and 33 are diagrams for explaining the thrust at both ends of the core of a conventional linear motor. FIG. 34 is a diagram showing the size of the coil end of the stator core. FIGS. 35 and 36 are diagrams for explaining a method of increasing the thrust of a conventional linear motor. FIG. 37 is an electric circuit diagram of a near motor drive circuit for increasing thrust. In the figure, 10 is a stator core, 10a is a tooth, 10b
are slots, 10c and 10d are winding spaces, 10e is a yoke, 20 is a conductor, 30 is a mounting base, 40a, 40b,
40a', 40b', 41a. 41b is a permanent magnet, 50 is a yoke, 60a is an air gap, 80 is a target, 101 is an OR circuit, 102 is an EXOR circuit, 103 is a multiplexer, 201 to 204 are ROMs, a to g are position detectors, C7 to C15 denotes a coil group, and Tr to Tr3° denote a power transistor.

Claims (9)

[Claims] (1) In a DC linear motor including a stator core around which a conductor is wound, and a field permanent magnet arranged opposite to the stator core and serving as a mover, the conductor is connected to the stator core and the field permanent magnet. The coils are wound in a ring shape over the gap and the back surface of the stator core, and the coils with the same number of turns per unit length in the sliding direction are electrically connected to form a coil group, and the length of one pole of the field permanent magnet is It is characterized by energizing so that current flows simultaneously in the same direction through a plurality of continuous coil groups that are longer than that, and arranging conductors that are energized over a sufficiently long section with respect to the pole length of the field permanent magnet. A DC linear motor. (2) The DC linear motor according to claim 1, wherein the distance between the poles of the field permanent magnet is selected to be twice the pitch of the coil group. (3) The stator core is made of formed and laminated electromagnetic steel plates, the length of which is selected to be an integral multiple of the length of the coil group, and a predetermined number of stator cores are arranged in the sliding direction by magnetically continuous means. A direct current linear motor according to claim 2. (4) The stator core is formed by laminating a plurality of square pieces of soft iron to have a predetermined size, or from a single square piece of soft iron having a predetermined size. The DC linear motor described in . (5) Two sets of the stator cores are provided so that the stator cores are arranged in the center, and each of the field permanent magnets is opposite to the two sets of stator cores, and each of the field permanent magnets has a different polarity, and the opposing conductors are energized. The DC linear motor according to any one of claims 1 to 4, wherein each coil group is electrically connected so that the coil groups are in the same direction. (6) The stator core is provided at the center, and the field permanent magnets are provided in two sets so as to face each side of the stator core and have the same polarity. The DC linear motor described in any of paragraphs. (7) The coil further includes a semiconductor element for switching the current flowing through the coil group, and adjacent coil groups are electrically connected to each other in series;
The DC linear motor according to claim 1 or 2, wherein the coil groups at both left and right ends are also electrically connected to each other, and the semiconductor element is arranged at each connection point. (8) Further, it includes position detection elements arranged to have an interval twice the pitch of the coil group, and a target having a length three times the pitch of the coil group and attached to the movable element. , a DC linear motor according to claim 1 or 2. (9) Claim 8 further includes a logic circuit that controls the semiconductor element based on three signals: a signal from two adjacent position detection elements and a logical sum signal of the signals on both sides. DC linear motor described in section.