JP2003061331A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motor small in size and high in rigidity wherein heat from an armature coil is efficiently transmitted to a frame and reduction is prevented in the thrust of a mover due to temperature rise in the armature coil. SOLUTION: In the linear motor 1, a flat plate-shaped heat pipe 7 is placed between a plurality of rows of coils constituting the armature coil 6 in the direction of the length of an armature 5. Further, part of the heat absorbing portion of the heat pipe 7 is bonded to the armature coil 6 and the heat radiating portion thereof is inserted into a coolant path 11. The heat pipe 7 is provided with a block-like engaging member 8 to be fixed on a frame 10 between the portion thereof to which the armature coil is bonded and the portion thereof inserted into the coolant path 11. Further, the frame 10 is provided with a hollow recessed portion 10a which constitues the coolant path 11 and is for inserting the heat radiating portion of the heat pipe 7 into the interior thereof, and an engaging stepped portion 10c which is capable of being engaged with the engaging member 8 installed on the heat pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor suitable for applications requiring ultra-precision positioning and high thrust, such as a transportation system for FA equipment.

[0002]

2. Description of the Related Art Conventionally, a linear motor suitable for applications requiring ultra-precision positioning and high thrust, such as a transportation system for FA equipment, is shown in FIG. FIG. 1 is an overall perspective view of a general linear motor, showing an overall configuration common to the present invention described later. Further, FIG. 5 shows a cooling structure of a conventional linear motor, which is taken along line A- of FIG.
It corresponds to a front sectional view taken along the line A. The linear motor of this example is a moving coil type in which an armature is a mover, and permanent magnets for field magnets arranged on both sides of the armature via magnetic gaps are stators, and the magnetic flux penetration is performed. An explanation will be given using a mold structure. In the figure, 1 is a linear motor, 2
Is a field yoke, 3 is a permanent magnet, 4 is a yoke base, 5 is an armature, 6 is an armature coil, 9 is a resin mold, 13 is a winding fixing frame, 14 is a frame, and 15 is a refrigerant passage.
In the linear motor 1, a plurality of permanent magnets 3 constituting field poles are arranged linearly on the side surfaces of two rows of field yokes 2 so that the N pole and the S pole have different polarities alternately. A yoke base 4 is arranged between the yokes 2 to form a stator. Further, in the linear motor 1, the armature 5 and the magnet array of the permanent magnets 3 are arranged to face each other in parallel with a magnetic gap. The armature 5 has two rows of coreless armature coils 6 formed by molding a plurality of coil groups into a flat plate shape, and
The armature coils 6 are linearly arranged on both sides of a winding fixing frame 13 made of metal such as stainless steel, and the winding fixing frame 13 and the armature coil 6 are fixed by a resin mold 9. Further, on the upper portion of the armature 5, the armature 5 is fixed along the longitudinal direction thereof, and a frame 14 having a T-shaped cross section made of metal such as stainless steel is provided. The armature 5 and the frame 14 are fixed to each other by inserting one end of the winding fixing frame 13 into the recess 14a of the frame and then fixing the brazing, welding, or bonding to integrate them. Here, a refrigerant passage 15 is provided inside the frame 14, and the refrigerant is supplied to the refrigerant passage 15 from a refrigerant supply device (not shown). A linear guide (not shown) including a slider and a guide rail is attached to the mover side and the stator side of the linear motor, and the mover is linearly moved with respect to the stator. In such a configuration, when a current is applied to the armature coil 6 of each phase from a power supply (not shown), the electromagnetic action between the armature coil 6 and the permanent magnet 3 causes a magnetic field between the armature coil 6 and the permanent magnet 3. An electromagnetic force acts in the longitudinal direction of the armature coil 6 from the magnetic field formed in the gap to generate thrust, which results in smooth linear movement. At this time, when a drive current for propelling the mover flows through the armature coil 6, the armature coil 6 generates heat due to internal resistance. However, the heat generated by the armature coil 6 causes the resin mold 9 and the winding wire to wind. After heat is transferred to the frame 14 through the fixed frame 13, heat is exchanged by the refrigerant circulating inside the refrigerant passage 15, and the entire armature 5 is cooled.

[0003]

However, the conventional technique has the following problems. (1) The armature coil 6 includes a resin mold 9 that covers the periphery of the coil group and a winding fixing frame 1 that holds the armature coil 6.
The thermal conductivity of No. 3 is extremely smaller than that of the armature coil 6.
Further, since the contact area between the winding fixing frame 13 and the frame 14 is small and the winding fixing frame 13 is not in direct contact with the refrigerant passage 15, the armature coil 6 to the refrigerant passage 15 are generally viewed. The thermal resistance in the route is large. That is,
Since the cooling capacity of the linear motor is determined by the thermal resistance between the armature coil 6 and the refrigerant passage 15, there is a limit to how to simply let the refrigerant flow to the frame 14 side, and the heat generated by the temperature rise of the armature coil 6 is limited. The heat could not be efficiently radiated to the frame 14. (2) According to (1), if the heat generated by the temperature rise of the armature coil 6 cannot be efficiently dissipated to the frame 14, the internal resistance of the armature coil 6 increases with the temperature rise of the armature coil 6. Rises and the drive current decreases. In this case, since the thrust of the mover of the linear motor 1 is proportional to the drive current, the reduction of the drive current significantly reduces the thrust of the mover of the linear motor 1. (3) Further, the winding fixing frame 1 is provided in the recess 14a of the frame 14.
In the method of inserting and fixing the one end of the winding 3, the winding fixing frame 13 is inserted into the frame 14 in a short length as shown in FIG. The structure of the frame 14 has a problem that the rigidity of the mover itself is lowered. As a result, when the mover travels, the mover vibrates on both sides of the mover in the direction of the facing stator via the magnetic gap, which deteriorates the motion accuracy. (4) As another conventional technique, although not shown, a linear motor having a structure in which a plurality of heat sinks for flowing a refrigerant are arranged between adjacent coils formed between the same armature coil rows. However, since a heat sink is externally attached to the outside of the winding fixing frame that fixes the armature coil, covering them with a resin mold increases the size of the armature and increases the number of assembly steps. , Could not be miniaturized. The present invention has been made to solve the above problems, and efficiently transfers the heat of the armature coil to the frame, and it is possible to prevent the thrust of the mover from decreasing with the temperature rise of the armature coil. It is an object of the present invention to provide a small and highly rigid linear motor.

[0004]

In order to solve the above-mentioned problems, the present invention according to claim 1 is a field magnet in which a plurality of permanent magnets forming field poles are alternately arranged so as to have different polarities. A yoke, an armature arranged to face the magnet array of the permanent magnets in parallel via a magnetic gap, and a frame fixing the armature and including a heat sink,
In a linear motor in which one of the field pole and the armature is a stator and the other is a mover so that the field pole and the armature travel relatively, The magnet and the field yoke are arranged in two rows, and the armature is provided between the field poles in two rows, and a plurality of coil groups are arranged in a flat plate shape in the longitudinal direction of the armature. Is formed of at least two rows of armature coils, and a flat plate-shaped heat pipe is arranged between the plurality of coil rows along the longitudinal direction of the armature and covers the coil rows. The heat pipe is fixed to the armature coil with a part of its heat absorbing portion, and the heat radiating portion is inserted into the heat sink. The present invention according to claim 2 is the linear motor according to claim 1, wherein the heat pipe is fixed to the frame between a portion to which the armature coil is fixed and a portion to be inserted into the heat sink. A block-shaped locking member is provided. According to a third aspect of the present invention, in the linear motor according to the first or second aspect, the frame constitutes the heat sink, and a hollow recess for inserting the heat radiating portion of the heat pipe therein. And a locking step portion having a step formed on the opening side of the recess and capable of locking with the locking member. According to a fourth aspect of the present invention, in the linear motor according to any one of the first to third aspects, the heat sink is composed of a refrigerant passage adapted to exchange heat with a refrigerant. According to a fifth aspect of the present invention, in the linear motor according to any one of the first to fourth aspects, the heat pipe includes a meandering hollow thin tube for enclosing the working fluid in a thin plate member. It is a thing. According to a sixth aspect of the present invention, in the linear motor according to any one of the first to fifth aspects, the heat pipe is made of stainless steel.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a linear motor according to an embodiment of the present invention, and is a front sectional view taken along the line AA of the linear motor of FIG. 1 as seen from the thrust direction. Note that the same components as those of the present invention are denoted by the same reference numerals, the description thereof will be omitted, and only different points will be described. Further, this embodiment shows an example of a linear motor having a magnetic flux penetration type structure as in the conventional example. In the figure, 7 is a heat pipe, 8 is a locking member, 1
0 is a frame. 10a is a recess, 10b is a locking end wall, 10
Reference numeral c is a locking stepped portion, 11 is a heat sink, and here, a refrigerant passage through which heat is exchanged by the refrigerant is shown. The present invention is different from the conventional one in the following points.
A flat plate-shaped heat pipe 7 is arranged along the longitudinal direction of the armature 5 between a plurality of coil rows constituting the armature coil 6, and is fixed by a resin mold 9 so as to cover the coil rows. Specifically, a part of the heat absorbing portion of the heat pipe 7 is fixed to the armature coil 6, and the heat radiating portion is arranged to be inserted into the refrigerant passage 11. Further, a block-shaped locking member 8 for fixing to the frame 10 is provided between a portion of the heat pipe 7 to which the armature coil is fixed and a portion to be inserted into the refrigerant passage 11. Further, the frame 10 forms a refrigerant passage 11 and has a hollow recess 10 a into which the heat dissipation portion of the heat pipe 7 is inserted, and a frame 10 formed on the opening side of the recess 10 a and attached to the heat pipe 7. The stopper member 8 is provided with a locking step portion 10c having a step capable of locking. Here, FIG. 3 is an enlarged perspective view of the heat pipe, showing a perspective view of the inside. In FIG. 3, 71 is a thin tube, 71a is a heat absorption part, and 71b is a heat dissipation part. As shown in the figure, the heat pipe 7 has a structure in which a large number of meandering hollow thin tubes 71 are lined up inside a thin metal plate member having good heat conduction, and is composed of a liquid phase working liquid such as CFC and a gas phase working liquid. The two-phase hydraulic fluid is sealed in a thin tube 71, and includes a heat absorbing portion 71a and a heat radiating portion 71b.

Next, the assembling of the armature and the frame constituting the linear motor will be described. FIG. 4 is an explanatory view showing an assembling process of the armature and the frame which form the linear motor of FIG. When fixing the armature 5 and the frame 10, first, the armature coil 6 is bonded to the heat absorbing portion of the heat pipe 7. Then, the locking member 8 is fixed to the upper end of the portion of the heat pipe 7 to which the armature coil 6 is fixed by welding, brazing, or bonding. Next, the recess 1 of the frame 10
After inserting the tip portion of the heat pipe 7 into 0a, the locking member 8 fixed to the heat pipe 7 is brought into contact with the locking step portion 10c of the frame 10 to lock the end wall 10b of the frame 10.
The tip of the armature 5 and the tip of the locking member 8 are fixed by welding, brazing, or adhering the armature 5 and the frame 10 to be integrated.

Next, the cooling mode of the linear motor will be described. When a drive current is passed through the armature coil 6 of the linear motor, the armature coil 6 generates heat due to internal resistance. The heat generated in the armature coil 6 is transmitted to the heat absorbing portion of the heat pipe 7, and when the heat absorbing portion absorbs the heat, intense nucleate boiling occurs. The pressure wave due to the intermittent nucleate boiling becomes a vibration wave, which causes vibration in the working fluid enclosed in the meandering thin tube 71, and a large amount of heat is transferred to the heat radiating portion due to the vibration of the working fluid. Then, the heat transferred to the heat dissipation portion of the heat pipe 7 is transferred to the refrigerant passage 11. As a result, the heat generated in the armature coil 6 is efficiently heat-exchanged in the refrigerant passage 11, and the temperature rise of the armature coil 6 is suppressed.

Next, when the cooling capacity of the linear motor according to the present embodiment is calculated, the thermal conductivity of the heat pipe 7 in the heat transfer direction becomes about 2000 W / m · ° C. or more. Is aluminum (thermal conductivity = approximately 200 W / m
The heat transfer capacity is 10 times or more that of the resin mold 9 and 1000 times or more of the thermal conductivity of the resin mold 9 (about 2 W / m.degree. C.). Therefore, conventionally, the armature coil 6
It is possible to efficiently take heat up to the vicinity of the end portion where the heat resistance is high, and the temperature rise of the armature coil 6 and the resin mold 9 can be reduced to at least one-tenth or less of the conventional temperature rise.

Therefore, a flat plate-shaped heat pipe 7 is arranged along the longitudinal direction of the armature 5 between a plurality of coil rows forming the armature coil 6, and a resin mold 9 is provided so as to cover the coil rows. Since the heat pipe 7 is fixed and a part of the heat absorbing portion of the heat pipe 7 is fixed to the armature coil 6 and the heat radiating portion is arranged to be inserted into the refrigerant passage 11, the armature coil 6 is caused. The heat is efficiently radiated to the refrigerant passage 11, and the temperature rise of the armature coil 6 can be significantly reduced. Further, since the heat generated by the armature coil 6 can be efficiently dissipated, the thrust of the mover can be increased without lowering the drive current. Further, a block-shaped locking member 8 for fixing to the frame 10 is provided between the portion of the heat pipe 7 to which the armature coil 6 is fixed and the portion to be inserted into the coolant passage 11, and the frame 10 is It is possible to engage with the hollow concave portion 10a which constitutes the refrigerant passage 11 and into which the heat radiation portion of the heat pipe 7 is inserted, and the locking member 8 which is formed on the opening side of the concave portion 10a and is attached to the heat pipe. Since the locking step portion 10c having the above step is provided,
The armature 5 and the frame 10 can be easily integrated with the locking member 8 and the locking step portion 10c, and the rigidity of the mover itself can be increased. As a result, when the mover travels, there is no problem that the mover vibrates on both sides of the mover in the direction of the facing stator via the magnetic gap, and the motion accuracy can be improved. Further, the heat pipe 7 has a structure in which a large number of meandering hollow thin tubes 6 having a heat absorbing portion and a heat radiating portion are arranged inside a thin plate member made of a metal having good heat conduction, so that the weight can be reduced without lowering the strength. It is possible to provide a small-sized linear motor that can reduce the number of assembling steps while maintaining the shape and size of the conventional winding fixing frame.

In the present embodiment, a moving coil type structure in which the armature of the linear motor is used as the mover and the field poles are used as the stator has been described as an example, but the armature of the linear motor is used as the stator and A moving magnet type structure may be used in which the magnetic poles are the movers. Further, in the present embodiment, an example in which the armature coil has two coil rows has been described.
A structure having three or more coil rows may be used, and in that case, the combination of the number of coil rows and the number of phases is not limited. The heat pipe 7 may be made of metal such as stainless steel or aluminum. When stainless steel is used for the heat pipe 7, the eddy current in the metal portion of the heat pipe 7 that occurs when the armature of the linear motor moves in the thrust direction along the rows of the permanent magnets 3 is reduced, and the eddy current is generated. It is possible to reduce the viscous resistance force of the mover. Also,
The heat pipe 7 has shown an example in which the liquid-phase working liquid and the gas-phase working liquid are enclosed in the meandering thin tube 71 to have the cooling characteristic of utilizing the nucleate boiling phenomenon, but the cooling characteristic is satisfied. If necessary, a heat pipe having another structure may be used. Further, although the heat sink 11 is a coolant passage configured to exchange heat with a coolant, a metal block (not shown) having high heat conductivity is provided in the recess 10A provided inside the frame 10.
May be fitted to each other, and the metal block may be projected from the length of the frame 10 in the longitudinal direction to radiate heat to the outside air.

[0011]

As described above, the present invention has the following effects. (1) A plate-shaped heat pipe is arranged along the longitudinal direction of the armature 5 between a plurality of coil rows forming the armature coil, and the coil rows are fixed by resin molding so as to cover the coil rows. Since a part of the heat absorbing part of the heat pipe is fixed to the armature coil and the heat radiating part is arranged to be inserted inside the refrigerant passage, the heat generated in the armature coil is efficiently radiated to the refrigerant passage. The temperature rise of the armature coil can be significantly reduced. (2) Since the heat generated by the armature coil can be efficiently dissipated, the thrust of the mover can be increased without reducing the drive current. (3) A block-shaped locking member for fixing to the frame is provided between the portion of the heat pipe to which the armature coil is fixed and the portion inserted into the refrigerant passage, and the frame constitutes the refrigerant passage. And a hollow recess for inserting the heat radiating portion of the heat pipe therein, and a step formed on the opening side of the recess and capable of being locked by a locking member attached to the heat pipe Since the armature and the frame are provided with the stopping step portion, the armature and the frame can be easily integrated with each other by the engaging member and the engaging step portion, and the rigidity of the mover itself can be increased. As a result, when the mover travels, there is no problem that the mover vibrates on both sides of the mover in the direction of the facing stator via the magnetic gap, and the motion accuracy can be improved. (4) Since the heat pipe has a structure in which a large number of meandering hollow thin tubes having a heat absorbing portion and a heat radiating portion are arranged inside a thin metal plate member having good heat conduction, it is possible to reduce the weight without lowering the strength. Moreover, it is possible to provide a small-sized linear motor capable of reducing the number of assembling steps while maintaining the shape and size of the conventional winding fixing frame.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a general linear motor,
1 shows an overall configuration common to the present invention and the prior art.

FIG. 2 is a front sectional view taken along the line AA of the linear motor of the embodiment of the present invention, the linear motor of FIG. 1 being viewed from the thrust direction.

FIG. 3 is an enlarged perspective view of a heat pipe, showing the inside thereof in a see-through manner.

FIG. 4 is an explanatory view showing an assembly process of an armature and a frame which form the linear motor of FIG.

5 shows a cooling structure of a conventional linear motor, and corresponds to a front sectional view taken along the line AA of FIG.

[Explanation of symbols]

1 linear motor 2 field yoke 3 permanent magnet 4 York base 5 armature 6 Armature coil 7 heat pipe 71 thin tube 71a Heat absorbing part 71b Heat dissipation part 8 locking member 9 resin mold 10 frames 10a recess 10b Locking end wall 10c Locking step 11 Refrigerant passage (heat sink)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H609 BB08 PP09 QQ04 QQ23 RR61                       RR62 RR63                 5H641 BB06 BB18 BB19 GG05 GG07                       GG11 GG12 HH02 HH03 HH05                       JB03 JB05 JB10

Claims (6)

[Claims] 1. A field yoke in which a plurality of permanent magnets forming field poles are alternately arranged so as to alternately have different polarities, and a field yoke is arranged in parallel with a magnet row of the permanent magnets via a magnetic gap. Fixed armature and said armature, and
A linear motor including a frame having a heat sink, wherein one of the field pole and the armature is a stator and the other is a mover so that the field pole and the armature travel relatively. The permanent magnets and field yokes forming the field poles are arranged in two rows, and the armature is provided between the field poles in the two rows, and a plurality of armatures are provided in the longitudinal direction. Of at least two rows of armature coils formed by arranging the above coil groups in a flat plate shape. A plate-shaped heat pipe is arranged along the longitudinal direction of the armature between the plurality of coil rows, and is fixed with a resin mold so as to cover the coil rows, and the heat pipe absorbs heat. A linear motor, wherein a part of the portion is fixed to the armature coil, and the heat radiation portion is arranged to be inserted into the heat sink. 2. A block-shaped locking member for fixing to the frame is provided between a portion of the heat pipe to which the armature coil is fixed and a portion inserted into the heat sink. The linear motor according to claim 1. 3. The frame constitutes the heat sink, and is formed on the opening side of the hollow portion with a hollow concave portion into which the heat radiation portion of the heat pipe is inserted, and the locking portion. The linear motor according to claim 1 or 2, further comprising: a locking step portion having a step that can be locked with the member. 4. The heat sink is constituted by a refrigerant passage adapted to exchange heat with a refrigerant.
The linear motor according to any one of 1 to 3. 5. The linear motor according to claim 1, wherein the heat pipe includes a meandering hollow thin tube for enclosing the working fluid inside a thin plate member. . 6. The linear motor according to claim 1, wherein a material of the heat pipe is stainless steel.