JP2000245130A - Moving-coil linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving-coil linear motor, capable of having a simple air-cooling structure and attaining high efficiency. SOLUTION: This moving-coil linear motor is provided with a plurality of permanent magnets 2, so that poles are alternately disposed differently from each other in the longitudinal direction of yokes 7 which face the permanent magnets, and the heteropoles face each other via a magnetic space 3, a mover 5 which has a polyphase coil and is movably disposed in the magnetic space 3 in the arrangement direction of the permanent magnet 2, and a drive circuit for supplying drive current to the polephase coil. A recessed groove 70 is formed in the surface 71, on which the magnet of the yoke 7 is arranged so as to continue in the longitudinal direction, the permanent magnet 2 is disposed in the longitudinal direction of the yoke 7 with prescribed intervals Lg open, and air is supplied to the recessed groove 70 and blown it into the magnetic space 3 from an air-gap 72, so as to cool the polyphase coil to reduce the temperature rise in the permanent magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor in which a mover coil moves linearly in a magnetic space formed between opposing yokes, and maintains a maximum current value of the mover coil and heats a permanent magnet. The present invention relates to a moving coil linear motor capable of improving the maximum thrust by suppressing demagnetization.

[0002]

2. Description of the Related Art Conventionally, as a driving device for positioning an object within a relatively long stroke range of several tens to 100 cm, for example, Japanese Patent Publication No. 58-49100
And a moving coil type linear motor as disclosed in JP-A-63-93783. This moving coil type linear motor will be described with reference to FIG. First, reference numeral 1 denotes a yoke which is formed in a gate shape by assembling a U-shaped or flat plate using a ferromagnetic material such as an iron plate. Numeral 2 denotes a permanent magnet which is magnetized in the thickness direction and is arranged and fixed in the longitudinal direction of the yoke 1 so that NS magnetic poles appear alternately on the surface. The different poles of the permanent magnet 2 are arranged so as to face each other. 4 is a support plate for the yoke 1
The yoke 1 is made of the same ferromagnetic material and is fixed to both ends in the longitudinal direction of the yoke 1 in order to secure the magnetic space 3.

[0003] Next, reference numeral 5 denotes a mover integrally provided with a coil, a holder and the like, which is formed by a flat multi-phase coil in which the magnetic flux in the magnetic space 3 and the winding direction are orthogonal. This means that, for example, three-phase coils are arranged with a slight shift in the direction in which the permanent magnets 2 are arranged, and the direction of the magnetic poles is changed to the magnetic field detecting element (M
(R sensor) or the like, and is configured to switch between driving and its direction by supplying a single-phase or three-phase sine wave current. A table 6 and the like indicated by a dotted line in the figure are attached to the mover, and a linear movement of the table 6 is used.

With the above configuration, when a current is applied to the coil 5, the winding direction of the coil 5 is orthogonal to the magnetic flux generated by the permanent magnet 2. Therefore, the coil 5 is moved in the longitudinal direction of the yoke 1 according to Fleming's left-hand rule. A driving force is obtained, and the mover integrally supporting the coil 5 moves in the longitudinal direction of the yoke 1. Next, when a current in the opposite direction is applied to the coil 5, a driving force in the opposite direction acts on the coil 5, so that the mover moves in the opposite direction. Therefore, the coil 5
The movable element can be controlled to move to a predetermined position by selecting the power supply and its direction and detecting the position with an MR sensor.

According to this moving coil type linear motor,
There is no center yoke in the magnetic circuit part, and the magnetic flux forms a plurality of closed loops in the magnetic space, so that the magnetic flux does not concentrate on a part of the magnetic path, so it is uniform throughout the long stroke High magnetic flux density can be generated. Further, the mass of the mover is small and the cogging torque is also small, so that the linear motor has a feature of good responsiveness.

However, since the coil 5 is arranged in the narrow magnetic space 3, the efficiency of heat exchange and heat dissipation by natural convection is low, and the coil 5, which is a heat source, is located on the mover side, so that cooling is not performed. There is a structural problem that it is difficult to take measures. Furthermore, the electric power of the coil itself increases due to the heat generated by the coil 5 and the Joule heat loss increases, so that the effective power decreases. For this reason, the power supplied to the coil 5 is limited to a value at which the heat generation of the coil does not cause a practical problem. On the other hand, the heat from the coil 5 is also transmitted to the opposing permanent magnet 2, the temperature of the permanent magnet 2 rises, and the generated magnetic flux decreases due to thermal demagnetization. From the above, there is a performance problem that the generated thrust is reduced.

Therefore, it is desired to cool the coil. For example, Japanese Utility Model Laid-Open No. 4-34878 proposes providing a plurality of axial fans on a side surface of a fixed yoke to cool the coil.

[0008]

However, in the cooling means disclosed in Japanese Utility Model Laid-Open No. 4-34878, the provision of an axial fan results in an increase in the size and the structure of the linear motor. Usually, in the case of a moving magnet type linear motor, the coil side does not move, so the means for cooling this can be implemented relatively efficiently with water cooling or air cooling, but in the case of a moving coil type linear motor, the coil side moves, It was difficult to take an efficient cooling structure. Therefore, the actual situation is that the moving coil linear motor does not include the cooling means.

Accordingly, the present invention is concerned with the latter conventional technique described above and solves the problem. An air cooling means which makes the air cooling structure of the coil inexpensive and simple and which can obtain an efficient effect. It is an object of the present invention to provide a moving coil type linear motor provided with:

[0010]

According to the present invention, a plurality of permanent magnets are alternately arranged in the longitudinal direction of a yoke so that magnetic poles are different from each other, and a coil is placed in a magnetic space formed along the surface of the magnet. In a moving coil linear motor in which a movable element provided is provided so as to be movable in a direction in which the permanent magnet is disposed, the permanent magnet is disposed at a predetermined gap in a longitudinal direction of the yoke, and the permanent magnet is disposed in a longitudinal direction of the yoke. A moving coil type linear motor that provides a passage, communicates the gap between the permanent magnets and the passage, supplies air to the passage, blows air into the magnetic space, and cools the coil. is there.

According to the present invention, there is provided a movable element having a plurality of permanent magnets arranged alternately in the longitudinal direction of a yoke so that magnetic poles are different from each other, and having a coil in a magnetic space formed along the surface of the magnet. In the movable coil linear motor, which is provided so as to be movable in the direction in which the permanent magnets are provided, while forming a continuous groove in the longitudinal direction on the magnet mounting surface of the yoke,
The permanent magnet is disposed with a predetermined gap so as to cover the groove, and air is blown into the magnetic space from the gap between the permanent magnets by supplying air to the groove,
A moving coil type linear motor configured to cool the coil.

Further, the present invention provides a mover having a plurality of permanent magnets arranged alternately in the longitudinal direction of a yoke so that magnetic poles are different, and a coil provided in a magnetic space formed along the surface of the magnet. In the moving coil linear motor, the permanent magnets are provided so as to be movable in the direction in which the permanent magnets are provided.The permanent magnets are provided with a predetermined gap in the longitudinal direction of the yoke. In addition to providing a continuous and sealed passage in the longitudinal direction on the non-exposed surface, forming a communication hole that communicates the gap between the permanent magnets and the passage, and supplying air to the passage, through the communication hole, This is a moving coil type linear motor that blows air into a magnetic space to cool the coil.

Here, the passage is formed by forming a continuous groove in the longitudinal direction and sealing the closed groove, or is fixed by sealing the concave member continuous in the longitudinal direction. Alternatively, it can be provided by a pipe-like material. In the moving coil linear motor, the permanent magnets may be provided so that different poles face both opposing yokes, or may be provided on only one side. However, permanent magnets are arranged at predetermined intervals, and in terms of a magnetic circuit, if a predetermined gap between adjacent permanent magnets is Lg and an alternating magnetic field period is Lm, for example, Lg is Lm / 3 to Lm / 8. And Lm / 4 or less is desirable. A plurality of grooves or air passages serving as passages for the cooling air may be provided above and below as appropriate. In the above, it is described that air cools the coil, but this means that at least the coil is cooled, and this does not prevent indirect cooling of the permanent magnet and the like.

According to the present invention, by providing a predetermined gap between adjacent permanent magnets, air can be blown into the magnetic space from this gap to efficiently cool the coil. If the air supply passage is formed as a concave groove or a closed concave groove, processing can be extremely easily performed even with a long yoke, and the length of the yoke is not restricted. Therefore, it is particularly suitable for a long linear motor such as a linear motor having a yoke with a driving distance of 10 cm or more. As described above, even a moving coil type linear motor can be provided with a simple and inexpensive cooling means, reducing both the heat loss on the coil side and the heat demagnetization on the magnet side to achieve a high thrust of the linear motor,
This can be kept.

The provision of the gap between the permanent magnets has the effect of making the magnetic flux distribution sinusoidal, which also contributes to the improvement of controllability. The predetermined gap Lg between the adjacent permanent magnets is set to Lm / 3 with respect to the alternating magnetic field period Lm in order to effectively generate a magnetic flux amount between the opposing permanent magnets.
Lm / 8 is set within the range of ~ Lm / 8. If the period of the alternating magnetic field is 16 to 100 mm, about 4 to 25 mm can be selected in a practical range, but it is particularly preferably about 8 to 15 mm from the viewpoint of the occupation area of the linear motor and economy. However, in a structure in which air is blown out from the groove formed in the magnet arrangement surface, it is sometimes better to have a nozzle function in the blowout port in consideration of cooling efficiency. In this case, Lg = 0. It may be set within a range of about 0.05 to 5 mm. Also, the number of the above-mentioned concave grooves, air passages and communication holes is appropriately set depending on the situation, and it is efficient to provide a plurality of yoke and magnets if the size becomes large.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial top view of a linear motor showing a first embodiment, and FIG. 2 is a sectional view taken along line AA of FIG.
FIG. 3 is a partial top view of a linear motor showing a second embodiment,
FIG. 4 is a sectional view taken along line BB of FIG. FIG. 5 is a sectional view of a main part showing another embodiment of the air passage. FIG. 6 is a cross-sectional view of a linear motor according to a third embodiment. FIG. 7 is a partial top view of a linear motor showing a fourth embodiment. These drawings are simplified diagrams showing the outline of the structure, and do not show the actual structure. The same reference numerals are given to the same components as those in the related art, and the description thereof will be omitted.

In FIGS. 1 and 2, the yoke 7 is composed of a flat plate made of a ferromagnetic material such as mild steel and arranged on the left and right sides and a lower yoke 73 also having a flat plate shape. The magnetic space 3 is formed along the surface. In addition, the lower yoke 73 may be an integrated body or a separately assembled body. A permanent magnet, for example, Nd—Fe—B is provided on the magnet mounting surface 71 of the left and right yoke 7 in the longitudinal direction.
The anisotropic sintered magnets 2 are arranged and fixed adjacently so that their polarities are alternately different, and are further arranged and fixed so that the opposite magnets have different polarities. A mover 5 composed of a multi-phase coil is provided in the magnetic space 3 similarly to the above-described conventional technique, and a sine-wave driving current from a driving circuit (not shown) is supplied to the multi-phase coil to move linearly. (Vertical direction on paper)
This is a moving coil type linear motor.
The space between the permanent magnet 2 and the mover 5 is not a large image as shown in the figure, but is actually provided with a gap of about 0.02 to 2 mm. Further, the embodiments of the permanent magnet and the mover are not limited to the above.

In this embodiment, a concave groove 70 which is continuous in the longitudinal direction is formed on the magnet mounting surface 71 of the yoke 7. Such a groove 70 can be easily and inexpensively manufactured by milling. Further, the permanent magnets 2 are directly fixed to the disposing surface 71 with an adhesive at predetermined intervals so as to cover the concave grooves 70. The interval at this time may be selected so that the alternating magnetic field approaches a more complete sine wave, but from the viewpoint of efficiently blowing the cooling air, it is preferable to set the interval to 0.1 mm. It is necessary to form a nozzle having a size of several millimeters to several millimeters. Therefore, the interval is selected in consideration of these conditions. An air supply port is provided at one end of the not-shown groove 70, where the groove 70 is configured as a cooling air supply passage. Therefore, when cooling air is supplied from one end of the air supply passage of the yoke 7 by a pneumatic drive source or an air compressor of the apparatus, the permanent magnet 2 is cooled from the back through the concave groove 70, and the air is supplied between the magnets. The movable element 5 can be blown out from the opening 72 of the gap (shown in an exaggerated manner) into the magnetic space 3 to directly cool the movable element 5.

Next, FIGS. 3 and 4 show a second embodiment. This example is an example in which a passage is provided on a surface other than the magnet disposition surface. Specifically, a concave groove 80 is provided on the back surface 86 side of the yoke, and a lid member 85 is hermetically sealed via a seal member. The air supply passage is closed. As another embodiment of the air passage, for example, the one shown in FIG. 5 may be used. In this example, a box-shaped member 88 having a concave cross section and a length is hermetically fixed to the yoke 8 by means such as welding. In addition, a structure in which a pipe-shaped pipe is additionally provided is also conceivable. The permanent magnet 2 is provided on the magnet arrangement surface 81 of this example.
The permanent magnet 2 is directly fixed by selecting the gap Lg between the adjacent magnets within a range of 8 to 15 mm so that the alternating magnetic field approaches a perfect sine wave. The opening 82 of the gap has a communication hole 84 (for example, φ
(Approximately 0.05 to 5 mm) is provided between the openings, or in some cases, by skipping one or two steps. Note that the communication hole is not limited to a circular shape, and may be, for example, an elongated slit shape.

Therefore, also in this embodiment, when the cooling air is supplied from one end of the yoke 7, the cooling air flows into the magnetic space 3 from the gap opening 82 between the magnets through the air passage of the sealed groove 80 and the communication hole 84. The air blows out and the coil of the mover 5 can be directly cooled. In this embodiment, since there is no groove on the back surface of the permanent magnet, the magnetic flux distribution is less disturbed than in the above embodiment, and the controllability is stable. Further, since cooling air is blown to the mover from right beside the through hole, the cooling efficiency is more improved than the flow of air along the longitudinal direction. Also, although the efficiency of cooling decreases, as another embodiment,
A concave groove is provided on the lower surface of the lower base 83, and the concave groove is closed by a lid member or the like, and a plurality of communication holes communicating with the magnetic space are formed in the longitudinal direction. May be cooled.

FIG. 6 shows a third embodiment.
The yoke of this example is an example of a moving coil type linear motor having a center yoke. A groove 70 constituting a cooling air supply passage is also provided on the center yoke side, and the number of grooves is two in parallel. Are provided. It is conceivable to increase the cooling capacity in this way when the size of the yoke and the permanent magnet increases.

FIG. 7 shows a fourth embodiment. In each of the embodiments described above, a permanent magnet is provided in each of the opposed yokes, and the permanent magnets are disposed and fixed so that the opposite poles face each other via the magnetic space.In this embodiment, the permanent magnet is provided only in one yoke. It is arranged. In this case, a moving coil type linear motor similar to the above can be made to function by taking into account the winding method of the coil, the yoke shape, and the magnetic force and shape of the permanent magnet. In the figure, the concave grooves 90 and the communication holes 94 are provided in the yokes on both sides. However, these may be provided only in the yoke 9R on one side, and cooling air may be blown from only one side, and the present invention is limited to these embodiments. Various combinations can be considered without any. As described above, according to each of the above-described embodiments, both the heat generation of the coil and the temperature rise of the permanent magnet can be suppressed, so that a large current can be supplied, and the thrust of the linear motor can be increased.

[0023]

As described above, the present invention provides a moving coil type linear motor in which a permanent magnet with a predetermined gap is provided and a cooling air supply passage communicating with the gap. Things. This gives 3
Even with a long yoke of 0 cm or more, processing of the air supply passage can be extremely easily and inexpensively configured. Specifically, when the concave groove is formed on the magnet mounting surface, most of the concave groove is directly covered by the permanent magnet disposed with a predetermined gap. On the other hand, when the groove was formed on the back surface or the like, the groove was closed to form a passage, and a communication hole was formed between the permanent magnets arranged with a predetermined gap. According to these examples, the magnetic flux distribution is converted into a sine wave to improve controllability, and cooling air is supplied into the magnetic space from the gap to directly cool the movable coil and suppress a rise in the temperature of the permanent magnet.
Therefore, it is possible to reduce both the heat loss on the coil side and the heat demagnetization on the magnet side, and to provide a high thrust without limiting the current supplied to the linear motor. Further, the application range of the linear motor can be expanded.

[Brief description of the drawings]

FIG. 1 is a partial top view of a linear motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a partial top view of a linear motor showing a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a sectional view of a main part showing another embodiment of the air passage.

FIG. 6 is a cross-sectional view of a linear motor according to a third embodiment of the present invention.

FIG. 7 is a partial top view of a linear motor showing a fourth embodiment of the present invention.

FIG. 8 is a top view showing an example of a conventional moving coil type linear motor.

[Explanation of symbols]

1: Yoke 2: permanent magnet 3: magnetic space 4: support plate 5: mover 6: table, etc. 7, 8, 9: yokes 70, 80, 90: concave groove 71, 81: magnet mounting surface 72, 82: Gap opening 73, 83: Lower base 84, 94: Communication hole 85: Lid member 88: Recessed box member

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (5)

[Claims] 1. A movable element having a coil provided in a magnetic space formed along a surface of a magnet, wherein a plurality of permanent magnets are alternately arranged in a longitudinal direction of a yoke so that magnetic poles are different from each other. Wherein the permanent magnet is disposed at a predetermined gap in the longitudinal direction of the yoke, and a passage is provided in the longitudinal direction of the yoke. A moving coil type linear motor, wherein a gap between the coil and the passage is communicated, and air is blown into the magnetic space by supplying air to the passage to cool the coil. 2. A permanent magnet comprising: a plurality of permanent magnets arranged alternately in a longitudinal direction of a yoke so that magnetic poles thereof are different; and a movable element having a coil in a magnetic space formed along a surface of the magnet. In the moving coil type linear motor which is provided so as to be movable in the disposing direction, a concave groove continuous in the longitudinal direction is formed on the magnet disposing surface of the yoke, and the permanent magnet covers the concave groove. Arranged with a predetermined gap,
A moving coil type linear motor, wherein air is blown into a magnetic space from a gap between the permanent magnets by supplying air to the concave groove to cool the coil. 3. A permanent magnet comprising a plurality of permanent magnets arranged alternately in the longitudinal direction of a yoke so that magnetic poles are different from each other, and a movable element having a coil in a magnetic space formed along a surface of the magnet. In the moving coil linear motor provided so as to be movable in the disposing direction, the permanent magnet is disposed with a predetermined gap in the longitudinal direction of the yoke, while the permanent magnet is disposed on a surface other than the magnet disposing surface of the yoke. In addition to providing a passage that is continuous and sealed in the direction, a communication hole that connects the gap between the permanent magnets and the passage is formed, and air is supplied to the passage so that air is supplied through the communication hole to the magnetic space. A moving coil type linear motor, wherein the moving coil is cooled by blowing the air into the inside. 4. The moving coil linear motor according to claim 3, wherein the passage is formed by forming a continuous groove in a longitudinal direction and sealingly closing the groove. 5. A predetermined gap between adjacent permanent magnets is Lg,
Assuming that the alternating magnetic field period is Lm, Lg is Lm / 3 to Lm.
5. The moving coil linear motor according to claim 1, wherein the ratio is / 8.