JP3361042B2 - Stator and linear motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling means for an armature coil in a linear motor for conveyance of a type in which a permanent magnet and an armature coil (polyphase coil) are relatively moved.

[0002]

2. Description of the Related Art Conventionally, a plurality of permanent magnets are magnetized so that adjacent magnetic poles are different from each other and fixedly arranged on a yoke via a magnetic gap so that polarities of different magnetic poles face each other. A linear motor having a multi-phase coil provided in a magnetic gap and configured to relatively move the permanent magnet and the multi-phase coil by supplying a drive current to the multi-phase coil is well known. Is.

In this type of linear motor, a structure in which a thrust is applied to a mover by causing a driving current to flow in a multiphase coil as described above is often used, but the coil generates heat when current is applied to the multiphase coil. When the coil heats up, the heat from the coil is also transferred to the permanent magnets arranged through a narrow magnetic gap, the temperature of the permanent magnets rises, and the magnetic flux generated from the permanent magnets decreases due to thermal demagnetization. Thrust is reduced. Also, the heat generated by the coil increases the electric resistance of the coil itself and increases Joule heat loss, resulting in a decrease in effective power. For this reason, the electric power supplied to the coil must be limited so that the heat generation of the coil does not become a practical problem, and as a result, the thrust of the linear motor is limited. Further, the temperature of the atmosphere may rise due to the heat generated by the coil, and the linear guide may be thermally deformed, resulting in a decrease in positioning accuracy.

As means for solving this problem, means for cooling the coil by an air cooling method or a water cooling method is adopted. In the air cooling method, for example, in a movable magnet type linear DC motor, a part of the yoke for closing the magnetic path of the field magnet is removed, and a through hole is formed in the yoke portion where the field magnet is not arranged, and the through hole is used. There is a method (Japanese Patent Laid-Open No. 6-165472) of disposing a cooling fan for sending cold air to the stator armature side. Further, for example, in Japanese Unexamined Patent Publication No. 6-165474, a movable magnet composed of a field magnet and a yoke is divided in a movable magnet type DC linear motor, and a cooling fan for blowing air to the coreless stator armature side is arranged between the divided movable elements. The method of setting is described. In the water cooling system, for example, Japanese Utility Model Laid-Open No. 6-41381 discloses a linear motor that directly cools a coil with a refrigerant. This means that the coil is housed in an airtight container provided with a coolant supply port and a coolant discharge port, the coolant such as water is supplied to directly cool the coil, and the coolant discharged and radiated by a radiator is returned to the container. It is a thing. Further, in the water cooling system, there is also a method of indirectly cooling the coil with a refrigerant. For example, it is a method in which long support members are provided at both ends in the width direction of an armature in which rectangular coils having an air core are arranged in a planar shape and a ladder shape, and a refrigerant is flown into the long members. In this method, the heat transferred from the coil to the long support member by heat transfer is removed by a refrigerant, and the coil is indirectly water-cooled.

[0005]

Since the inside of the linear motor is not necessarily structured so that air easily flows, the air cooling system may not be able to perform sufficient and uniform cooling.
Further, it requires a space for installing a cooling fan, which is also disadvantageous for downsizing. The method of directly cooling the coil by storing the coil in the container and supplying the refrigerant can sufficiently cool the coil, but since the field magnet is installed outside the container, the coil and the field magnet are sufficiently close to each other. I can't let you do it. As a result, the thrust of the linear motor is limited. Further, since the refrigerant comes into contact with the coil, if water is used as the refrigerant, there is a problem of rust, and if oil is used, there is a problem in terms of explosion proof, so it is difficult to select the refrigerant. In the water cooling method of indirectly cooling the coil with the refrigerant, the cooling area cannot be sufficiently taken, and the cooling rate of the coil is the heat transfer rate of the coil, the heat transfer rate of the long supporting member provided in the armature and the coil. Since the rate of heat transfer on the contact surface with the long support member is limited, the coil may not be cooled sufficiently.

An object of the present invention is to solve the above problems existing in the prior art and to provide a linear motor which can obtain a sufficient thrust and can also sufficiently cool a coil.

[0007]

A mover having a field magnet forming a magnetic gap, and an armature coil group arranged along a moving path of the mover are provided in the magnetic gap. In a linear motor configured to hold a part or all of the armature coil group, an armature coil group arranged along a moving path of a mover and a flow path for flowing a coolant provided in close contact with the armature coil group And a long support member having
In addition, the air-core portion provided in each armature coil forming the armature coil group has a thermal conductivity of 10 W / m ° K or more and an electrical resistivity of 10 ⁶
The above object is achieved by using a stator in which a core made of a non-magnetic material of Ω · cm or more and having substantially the same thickness as the armature coil is provided in close contact with the armature coil and the long supporting member. The inventor has found that it is effective for.

The present invention is most characterized in that the air-core portion provided in the armature coil is used as a space for cooling the coil. The armature coil group of the stator is composed of a plurality of armature coils formed by winding a large number of conducting wires so as to have an air-core portion, and the armature coil and its air-core portion are generally rectangular in shape. Even if the coil is wound around the core described later,
Alternatively, only the coil may be separately wound so that the shape of the air-core portion substantially matches the shape of the core, and then the core may be fitted into the air-core portion. For the coil, a conductive wire coated beforehand with resin is used so that the winding does not come apart. After winding, the wire is heated to harden or impregnated with resin to harden. The armature coils are arranged along the path along which the mover moves, and when the armature coils have a rectangular shape, the armature coil group has a ladder shape. Adjacent armature coils are arranged in close contact with each other so that they do not overlap, or with a gap.
It is also possible to arrange the coils so that they partially overlap each other. In the present invention, the former arrangement is suitable. All armature coils are fixed to a long support member described later at a position where they do not interfere with the moving mover. The armature coil and the long support member need to be in close contact with each other at their contact surfaces in order to efficiently transfer the heat generated by the coil to the long support member, and when fixing, match the shape of the coil as much as possible. The recessed portion is provided on the long support member and fixed by adhesion or the recessed portion is tightened with a screw or the like to fix the coil by frictional force. The contact area between the coil and the long support member should be as large as possible to increase the cooling rate.

Next, the core will be described. The core needs to have high thermal conductivity, high electrical resistivity and non-magnetic properties. The core provided in the air-core portion of the armature coil cools the coil by receiving the heat generated in the coil from the contact surface with the coil by heat transfer and passing the heat to a long support member described later.
For that purpose, it is necessary that the core and the long support member are in contact with each other, and in order to efficiently transfer the received heat to the long support member, it is preferable that the contact area is large and they are in close contact with each other. The higher the thermal conductivity of the core material, the better. When the thermal conductivity is low, the coil is insufficiently cooled and the temperature of the coil becomes high. As a result, the above-mentioned problems occur such that the thrust of the linear motor is reduced and the positioning accuracy is reduced. Specifically, the thermal conductivity of the core material is preferably 10 W / m ° K or more at 25 ° C. In addition, in order to efficiently transfer the heat generated in the coil to the core, it is necessary that the core and the coil are in close contact with each other at the contact surface, and an adhesive with high heat transfer and heat resistance is applied to the contact surface of the core. You should keep it.

The higher the electrical resistivity of the core material, the better in order to suppress the eddy current generated in the core material when the core material crosses the magnetic flux due to the relative movement with the field magnet when the mover moves. . When an eddy current is generated in the core material, there are problems that the thrust of the linear motor is reduced and heat is generated. Specifically, the electrical resistivity of the core material is preferably 10 ⁶ Ω · cm or more at 25 ° C.

In the present invention, the core is preferably a non-magnetic material. By preventing the generation of magnetic attraction between the field magnet that forms the magnetic gap and the core,
This is to suppress the thrust ripple of the linear motor.

In the present invention, the core material is, for example, BN.
(Preferably hexagonal boron nitride), AlN, TiN, S
i ₃ N ₄ , known nitrides such as sialon, and B ₂ O ₃ ,
MgO, MnO, Al ₂ O ₃ , SiO ₂ , ZnO, Ti
O ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , BaO, BeO, C
Known oxides such as aO and K ₂ O, and SiC and Ti
Well-known carbides such as C, ZrC, TaC, B ₄ C, WC, W ₂ C, and 2MgO.SiO ₂ , MgO.SiO ₂ , C
aO ・ SiO ₃ , ZrO ₂・ SiO ₂ , 3Al ₂ O ₃・ 2S
iO ₂ , 2MgO.2Al ₂ O ₃ .5SiO ₂ , Li ₂ O.
Known silicates such 2Al ₂ O ₃ · 4SiO _2, and A
l ₂ TiO ₅ , MgAl ₂ O ₄ , Ca ₁₀ (PO ₄ ) ₆ (OH)
₂ , BaTiO ₃ , Pb (Zr, Ti) O ₃ , (Pb, L
a) One or more of the complex oxides of (Zr, Ti) O ₃ , LiNbO _{3 and the} like, and the composite sintered body of AlN and BN can be used. Of these, AlN and BN composite sintered bodies, AlN, Al ₂ O ₃ and BN (preferably hexagonal boron nitride) are preferable, and AlN and BN composite sintered bodies are particularly preferable. The core must be in close contact with the armature coil and the long support member in order to efficiently remove the heat generated in the armature coil, but for that purpose, the core must have high dimensional accuracy. AlN and B
Since the composite sintered body of N has a Vickers hardness of about 390, it is easily machined and high dimensional accuracy can be easily obtained.

The composition of the composite sintered body of AlN and BN used in the present invention is 50 to 97% by weight of aluminum nitride, 3 to 50% by weight of boron nitride (preferably 5 to 35% by weight), and the periodic table. At least one metal compound selected from Group IIa and Group IIIa metals is contained in an amount of 0.01 to 10% by weight (preferably 0.05 to 5% by weight) based on the mixture of aluminum nitride and boron nitride. Just select it. Be, C as the metal of Group IIa of the periodic table
Preferred are a, Sr, Ba, and the like. Further, Y or a lanthanum group metal is preferably used as the metal of Group IIIa of the periodic table, and more specifically, Y, La, Ce, P
r, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, etc., especially Y, La, Ce,
Nd and the like are preferable. These Periodic Tables IIa or III
The metal compound of group a is not particularly limited, and the above-mentioned metal compound known as a sintering aid for aluminum nitride powder and / or boron nitride powder can be used. Generally, for example,
Compounds such as nitrates, carbonates, chlorides and oxides are preferably used. When the nitrate of the above metal compound is used, it is converted into a nitrite by heating in an oxygen-containing gas atmosphere, but a carbonate or a chloride is converted into an oxide. Also, the periodic table IIa and II
The amount of at least one metal compound selected from the Group Ia metals used is 0.01 to 0.05% by weight, preferably 0.1% by weight, in the composite sintered body, by converting the sintering additive into an oxide. 05
It may be selected from the range of up to 4% by weight. The addition amount of these may be appropriately selected in consideration of the oxygen content in the composite sintered body, the content of impurities, the physical properties required for the composite sintered body, and the like. And AlN and BN used in the present invention
When the inevitable impurities include at least one metal compound selected from the above-mentioned Group IIa and Group IIIa metals, the composite sintered body of Ca contains 450 ppm of Ca, 60 ppm of Cr, and M.
g is 15ppm, Ni is less than 5ppm, Fe is 20pp
m and Si are less than 15 ppm, and O is an unavoidable impurity of about 0.5% by weight.

Next, a description will be given of a long support member which is provided in close contact with the armature coil group and which has a flow path for a refrigerant. The long support member carries out the heat received from the coil and the core to the outside of the system by the refrigerant, and also serves as a frame for fixing the armature coil group. The flow path of the refrigerant preferably has a large cross-sectional area in order to have a large heat transfer area, and is preferably arranged in a well-balanced manner in the cross section of the long support member. Since the refrigerant does not come into direct contact with the coil, water or oil can be freely selected. The refrigerant is radiated by a radiator outside the system and then returned to the container and can be used repeatedly. Further, when water or the like is used as the refrigerant, it can be disposable in one pass, in which case a radiator outside the system is unnecessary.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a cross-sectional view of an essential part showing an embodiment of a movable magnet type linear motor according to the present invention.
1B is a sectional view taken along the line AA in FIG. 1A (the horizontal yoke 7b is not shown). As shown in FIG. 1A, the field magnet 6 is arranged so that different magnetic poles face each other,
It is fixed to a pair of vertical yokes 7a (made of SS41 which is a ferromagnetic material) by using an epoxy adhesive. The pair of vertical yokes 7a and horizontal yokes 7b, which are ferromagnetic materials, form the yoke 7 and the mover 8 together with the field magnet 6. The field magnets 6 are also arranged in the moving direction of the mover, and adjacent field magnets have opposite polarities. The field magnet 6 fixed to the vertical yoke 7a, which is a ferromagnetic material, forms a magnetic circuit with the adjacent field magnets, and forms a magnetic gap between the field magnets 6 facing each other. The armature coil 1 having the core 2 bonded and fixed to the air core is further bonded and fixed to the long support member 3 to form the stator 5. The mover 8 is arranged so that the field magnet 6 is as close as possible to the armature coil 1 so that the armature coil 1 is located in the magnetic gap. The mover 8 is movably supported by a guide mechanism (not shown).

The field magnet 6 is an Nd-Fe-B type anisotropic sintered magnet manufactured by Hitachi Metals, Ltd. The surface of the field magnet 6 is provided with treatments such as Ni plating and electrodeposition epoxy coating. . The armature coil 1 was prepared by coating a conductor wire made of Cu alloy with an insulator and further coating it with a resin for fusing to heat the conductor wires. The core 2 is made of a composite sintered body of AlN and BN (Shapal Msoft manufactured by Tokuyama Corporation), and the main component is A
The composition is 65% by weight of 1N and 35% by weight of BN. In the sintering of this composite sintered body, as at least one metal compound selected from Group IIa and Group IIIa metals of the Periodic Table, 8.4 parts by weight of calcium nitrate tetrahydrate with respect to 100 parts by weight of a mixture of AlN and BN. Parts are added as sintering aids. Also, this composite sintered body contains Ca of 450 ppm and Cr of 60
ppm, Mg is 15 ppm, Ni is less than 5 ppm, Fe
Of 20 ppm, Si of less than 15 ppm, and O of 0.5 wt% as unavoidable impurities. Example 1 was a core 2 using the composite sintered body Msoft of AlN and BN having this composition. In Example 2, α-Al ₂
O ₃ was used. In Comparative Example 1, an epoxy resin was used, and in Comparative Example 2
Aluminum was used in Comparative Example 3 and no core was used in Comparative Example 3. The properties of these materials are shown in Table 1.

An epoxy adhesive was used to bond the armature coil 1 to the core 2 and to bond the armature coil 1 to the long support member 3. At this time, the core 2 was also bonded to the long supporting member 3 in the same manner.

The long support member 3 is preferably made of a non-magnetic material such as aluminum or aluminum alloy so as not to affect the magnetic gap. Here, it is made of aluminum alloy. The long support member 3 was formed with a coolant passage 4 in the longitudinal direction, and the respective passages were connected to form a single passage. Water at room temperature (25 ° C.) was continuously passed through the channel as a refrigerant in one pass. The long support member 3 can be formed by extrusion molding, casting, etc., and the flow path 4 is also formed at that time. In the case of extrusion molding, it is necessary to make the thickness of each part substantially uniform.

Table 2 shows the experimental values of the coil temperature rise of each Example and Comparative Example. Here, the coil has a direct current of 1
A was continuously energized, and water at 25 ° C. at a flow rate of 1 liter / min was flown through the flow path of the support member. The coil temperature was an average temperature of the entire coil and was measured by an electric resistance method utilizing the relationship between the coil temperature and the electric resistance. The coil surface temperature was measured by a surface thermometer. Both the coil temperature and the coil surface temperature are values when the steady state is reached. From this result, Comparative Example 2 using aluminum as the core shows the lowest coil temperature, but as described above, it is difficult to apply it to an actual motor due to the influence of eddy current loss and the like. The epoxy resin (Comparative Example 1) has some effect of reducing the coil temperature as compared with the case without the core (Comparative Example 3), but the coil surface temperature hardly changes. Example 1 according to the present invention
And 2 show a significant reduction in coil temperature.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

According to the present invention, since the armature coil core is provided with the core made of a specific material, the heat generated from the armature coil can be efficiently transmitted to the long supporting member, and the thrust of the linear motor can be obtained. It does not adversely affect the occurrence.

[Brief description of drawings]

FIG. 1A is a sectional view of an essential part showing an embodiment of a linear motor according to the present invention, and FIG. 1B is a sectional view taken along the line AA of FIG. 1A excluding a horizontal yoke 7b.

[Explanation of symbols]

1 armature coil, 2 cores, 3 long support members, 4
Flow path, 5 stator 6, field magnet, 7 yoke, 7a vertical yoke,
7b Horizontal yoke 8 Moving element

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02K 41/02-41/035 H02K 9/00-9/28

Claims (2)

(57) [Claims] 1. An electric machine comprising: an armature coil group arranged along a moving path of a mover; and a long support member provided in close contact with the armature coil group and having a flow path for flowing a refrigerant. The air-core portion provided in each armature coil forming the child coil group is made of a non-magnetic material having a thermal conductivity of 10 W / m ° K or more and an electrical resistivity of 10 ⁶ Ω · cm or more, and has substantially the same thickness as the armature coil. A core provided in close contact with the armature coil and the long supporting member. 2. A mover provided with a field magnet forming a magnetic gap, and the stator according to claim 1, wherein the mover comprises:
Part or all of the armature coil group in the magnetic gap
A linear motor characterized in that it is movably supported so as to be positioned .