JP6740088B2 - Linear motor - Google Patents

Description

The present invention relates to a movable magnet type linear motor.

Products with complicated shapes and structures such as cameras and printer cartridges are often assembled by assembly line production lines. In the production line, adjacent assembling devices are connected via a carrying device. The work, which is the object to be assembled, is sequentially transferred to each of the assembling devices by the transport device and continuously processed. When a high assembling accuracy of several μm to several tens of μm is required, the work transferred by the transfer device is positioned by the positioning device. Thereby, the assembling apparatus can perform the assembling with desired accuracy.

As a drive source of a transfer device, a movable magnet type linear motor having a magnet on the mover side and a coil on the stator side is known. The movable magnet linear motor includes a plurality of coils arranged along the traveling path of the mover. The movable magnet linear motor can magnetically drive a mover by appropriately supplying a drive current to a plurality of coils to carry a long length of conveyance. A ball circulation slider and a guide rail are used for the traveling path of the mover, and the mover can perform linear movement with high accuracy.

Since the linear motor has no backlash as compared with the ball screw type transfer device, it has high positioning accuracy and high repeatability. For this reason, linear motors have come to be used in high-speed transport devices for production lines for precision equipment.

Patent Document 1 discloses a movable magnet type linear motor including a mover having a permanent magnet unit and a stator having an armature unit. In Patent Document 1, since the armature unit is arranged so as to sandwich the permanent magnet unit, the attraction force acting between the excitation core of the armature unit and the permanent magnet of the permanent magnet unit is offset. Thereby, the deformation of the stator frame due to the suction force can be suppressed.

JP-A-11-113238 (FIG. 1)

However, in Patent Document 1, when the speed and density of the mover are increased, the heat generation amount of the coil increases, and the heat from the coil is transferred to the frame that fixes the coil. Since the frame is bent due to thermal expansion of the frame, the stop accuracy of the mover that moves along the guide rails on the frame deteriorates. Further, the position of the position detector is displaced due to the thermal expansion of the frame, which deteriorates the accuracy of detecting the position of the mover.

The present invention has been made in view of such a problem, and an object thereof is to provide a linear motor capable of suppressing deformation of the frame due to coil heat generation and improving positioning accuracy of the mover.

A linear motor according to an embodiment of the present invention includes a guide rail to which a mover unit having a permanent magnet is movable, a frame supporting the guide rail and connected to a coil unit, the coil unit and the frame. And a heat transfer member having one end connected to the coil unit and the other end connected to a heat radiating portion, and the frame has a wall portion extending along the guide rail. A through hole through which the heat transfer member penetrates is formed in the wall portion, and a heat insulating layer is provided between the through hole and the heat transfer member.

According to the present invention, it is possible to suppress the deformation of the frame due to the heat generation of the coil and improve the positioning accuracy of the mover.

It is a side view of the linear motor which concerns on 1st Embodiment of this invention. It is sectional drawing of the linear motor which concerns on 1st Embodiment of this invention. It is a figure for explaining the heat transfer structure concerning a 1st embodiment of the present invention. It is sectional drawing of the linear motor which concerns on 2nd Embodiment of this invention. It is a side view of the linear motor which concerns on 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
First, the structure of the linear motor according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view of the linear motor according to the present embodiment. FIG. 2 is a sectional view of the linear motor taken along the line AA′ in FIG. The linear motor 1 is a movable magnet type linear motor, and includes a mover unit 10 and a stator unit 20. In FIG. 1, the X direction (arrow direction) represents the moving direction of the mover unit 10, and the Y direction represents the width direction of the mover unit 10. The Z direction is a direction perpendicular to the ground plane and represents a vertical direction orthogonal to the X direction and the Y direction. A plurality of stator units 20 are provided side by side along the moving direction (X direction) of the mover unit 10. A plurality of mover units 10 are movably mounted on the plurality of stator units 20. In FIG. 1, for convenience, only two mover units 10 and two stator units 20 are shown.

The stator unit 20 includes a frame 30, a coil unit 33, a through hole 29, a heat transfer material 25, a heat radiating plate 26, a heat insulating spacer 23, a fixing screw 24, a heat insulating layer 32, an encoder 27, a bracket 28, and a guide rail 31. There is.

The frame 30 has a U-shaped or concave cross-sectional shape, and has a bottom portion 30C parallel to the XY plane, and wall portions 30A and 30B extending from the bottom portion 30C in the vertical direction (Z direction). There is. A guide rail 31 is fixed to the upper surface of each of the walls 30A and 30B, a gap is formed between the walls 30A and 30B, and a coil unit 33 is arranged in the gap. The frame 30 is preferably formed by casting, for example, and preferably has high rigidity.

The coil units 33 form a pair and are provided inside the wall portions 30A and 30B of the frame 30, respectively. The coil unit 33 has a plurality of coils 21, and the coil 21 is wound around the exciting core 22. The plurality of coils 21 are arranged in the X direction in the coil unit 33. An air gap is formed between the pair of coil units 33, and the magnet portion 12 of the mover unit 10 can pass through the air gap. The exciting core 22 is made of iron and is fixed to the wall portions 30A and 30B by a fixing screw 24. By appropriately switching the coil 21 to which the current is supplied according to the position of the mover unit 10, the magnet portion 12 of the mover unit 10 receives a propulsive force in the X direction. Therefore, the mover unit 10 can move along the stator unit 20.

The walls 30A, 30B and the bottom 30C of the frame 30 are integrally processed with high precision, and the gap of the exciting core 22 with respect to the magnet portion 12 is uniform. As a result, the attraction force in the left-right direction (Y direction) acting between the excitation core 22 and the magnet portion 12 can be offset.

A plurality of through holes 29 are formed in the wall portions 30A and 30B of the frame 30. The through holes 29 are formed between the encoders 27 in the X direction as shown in FIG. The through holes 29 are formed at symmetrical positions in the wall portions 30A and 30B. That is, the through hole 29 is formed in the one wall portion 30A at a position facing the through hole 29 of the other wall portion 30B.

The diameter of the through hole 29 is larger than the diameter of the heat transfer material 25, and the heat transfer material 25 is passed through the through hole 29. A gap is provided between the through hole 29 and the heat transfer material 25, and the gap is uniform in the circumferential direction of the through hole 29 (XZ plane direction). The gap between the through hole 29 and the heat transfer material 25 does not necessarily have to be uniform. For example, since heat is easily transferred in the upper direction, the upper portion of the through hole 29 may be formed into a long hole to widen the upper void. That is, the through hole 29 may have an elliptical shape having a long diameter in the vertical direction with respect to the guide rail 31 on the wall portions 30A and 30B of the frame 30. The shape of the through hole 29 is not limited to a circle or an ellipse, and may be a polygon such as a rectangle or a hexagon. The opening area of the through hole 29 can be appropriately designed according to the side areas and thicknesses of the wall portions 30A and 30B of the frame 30 so that the rigidity of the frame 30 is maintained. For example, the opening area of the through hole 29 can be set to 5 to 10% or less (5% or less, 10% or less) with respect to the side areas of the wall portions 30A and 30B of the frame 30. Further, the diameter of the through hole 29 is preferably smaller than the thickness of the wall portions 30A and 30B in order to secure the rigidity of the frame 30.

The heat transfer material 25 has a columnar shape, and is preferably made of a material having a thermal conductivity of 200 [W/m·K] or more, such as copper or aluminum. Further, the heat transfer material 25 may have an anisotropic crystal structure in which heat is easily transferred in the axial direction. The cross-sectional shape of the heat transfer material 25 is not limited to a circle, and may be a polygon. The heat transfer material 25 extends through the through hole 29 to the outside of the wall portions 30A and 30B of the frame 30. The heat transfer material 25 is arranged in the vertical direction (Y direction) with respect to the wall portions 30A and 30B of the frame 30. One end of the heat transfer material 25 is connected to the exciting core 22 and the other end is connected to the heat dissipation plate 26. That is, the coil unit 33 and the heat dissipation plate 26 are connected via the heat transfer material 25, and the heat generated in the coil unit 33 is transferred to the heat transfer material 25. The heat transfer material 25 constitutes a heat transfer member.

The heat dissipation plate 26 is provided outside the walls 30A and 30B of the frame 30 and radiates the heat from the heat transfer material 25 to the atmosphere. The heat dissipation plate 26 is provided outside the encoder 27 with respect to the wall portion 30A of the frame 30 so as not to contact the encoder 27. The heat dissipation plate 26 is formed of a material having a thermal conductivity of 200 [W/m·K] or more, such as copper and aluminum, like the heat transfer material 25. Since the heat dissipation plate 26 can easily secure a large surface area and cross-sectional area as compared with the heat transfer material 25, it is preferable to use an inexpensive material such as aluminum from the viewpoint of manufacturing cost. A cooling device such as a cooling fan or a cooling fin may be attached to the heat dissipation plate 26 in order to improve heat dissipation efficiency. The heat dissipation plate 26 constitutes a heat dissipation part.

The heat dissipation plate 26 is arranged so as to face the walls 30A and 30B of the frame 30, and has a substantially rectangular plate shape. The length of the heat dissipation plate 26 in the direction along the guide rail 31 (X direction) is slightly shorter than the length of the frame 30 in the direction along the guide rail 31. Therefore, the plurality of stator units 20 can be installed adjacent to each other without the heat sinks 26 interfering with each other.

The heat insulating spacer 23 is a heat insulating member and is made of a material having a thermal conductivity of 0.5 [W/m·K] or less, such as polyacetal resin. The heat insulating spacer 23 is provided between the coil unit 33 and the frame 30. The fixing screw 24 has a head portion and a body portion and is used together with the heat insulating spacer 23. That is, the heat insulating spacers 23 are arranged at the fixing portions between the excitation core 22 and the walls 30A and 30B of the frame 30 and the fixing portions between the walls 30A and 30B of the frame 30 and the heads of the fixing screws 24. The contact area between the excitation core 22 and the frame 30 is smaller than that in the case where the heat insulating spacer 23 is not used. An air layer (space) is provided between the fixing screw 24 and the frame 30, and the fixing screw 24 does not contact the frame 30. The heat insulating spacer 23 constitutes a heat insulating portion.

The heat insulating layer 32 is a layer having a low thermal conductivity, for example, an air layer, and is provided between the through hole 29 and the heat transfer material 25. The heat insulating layer 32 has a thermal resistance larger than that of the heat transfer material 25, and prevents or suppresses heat transfer from the heat transfer material 25 to the frame 30. In order to maintain the rigidity of the frame 30, it is preferable to thin the heat insulating layer 32 and reduce the diameter of the through hole 29.

The encoder 27 is fixed to an upper end portion of a plate-shaped bracket 28 and is arranged between the heat dissipation plate 26 and the wall portion 30A of the frame 30. The lower end of the bracket 28 is fixed on the pedestal 40, and the encoder 27 is thermally insulated from the frame 30. The lower end of the bracket 28 may be connected to a cooling device such as a refrigerant type. The encoder 27 is provided with a reading head 27a. The reading head 27a includes, for example, a light emitting element and a light receiving device, and can detect the scale of the linear scale 14. The encoder 27 constitutes a detection unit, and detects the position of the mover unit 10 in the X direction, for example, as a relative position with respect to the read head 27a.

The length of the linear scale 14 in the X direction is longer than the installation interval of the read head 27a of the encoder 27. Therefore, wherever the mover unit 10 is located on the stator unit 20, the position of the mover unit 10 can be detected by any one of the encoders 27.

One encoder 27 is arranged corresponding to the three coils 21. The three coils 21 form U-phase, V-phase, and W-phase, respectively, and are connected to a driving device (not shown) that outputs 3-phase AC power. The movement of the mover unit 10 can be controlled by supplying three-phase AC power to the three coils 21.

The guide rail 31 is composed of a pair of parallel rails, and is fixed to the upper surfaces of the wall portions 30A and 30B of the frame 30, respectively. The mover unit 10 is movably mounted on the guide rail 31 via the slider 13. The guide rail 31 forms a traveling path of the mover unit 10. As described above, the attractive forces acting between the exciting core 22 and the magnet portion 12 are canceled out, so that the rigidity in the Y direction required for the slider 13 and the guide rail 31 is reduced. Therefore, the widths of the guide rail 31 and the slider 13 can be narrowed as compared with the case where the cancellation of the suction force is small.

The mover unit 10 includes a work holder 11, a magnet portion 12, a slider 13, a linear scale 14, and a scale bracket 15. The work holder 11 is arranged above the mover unit 10, and has a stage on which the work 100 is placed, a mechanism for attaching and detaching the work 100, and the like. A space matching the shape of the work 100 is formed in the central portion of the work holder 11, and the work 100 is detachably held in this space.

On the lower surface of the work holder 11, a plate-shaped magnet portion 12 extending in the XZ plane is provided so as to project. The magnet unit 12 has a permanent magnet and a bracket, and the permanent magnet is fixed to the surface of the bracket. The bracket is a plate-shaped support member, and the upper end of the bracket is fixed to the center of the lower surface of the work holder 11. The magnet unit 12 can move in the X direction through the gap between the pair of coil units 33.

Further, a slider 13 is fixed to the lower surface of the work holder 11. The sliders 13 are arranged in a pair along the X direction at both ends of the lower surface of the work holder 11. The cross section of the slider 13 has a concave shape that opens downward, and the slider 13 is mounted so as to straddle the guide rail 31. The slider 13 has a ball circulation type slide mechanism, and the work holder 11 can move along the guide rail 31 with a small resistance.

The linear scale 14 is a strip-shaped member extending in the X direction, and is fixed to the lower end portion of the scale bracket 15. The scale bracket 15 is a plate-shaped support member, and the upper end portion of the scale bracket 15 is fixed to the lower side surface of the work holder 11. The linear scale 14 has an optical or magnetic scale and is read by a plurality of encoders 27 provided so as to face the linear scale 14.

The work 100 is loaded on the work holder 11 and conveyed to an assembling device (not shown). The assembling apparatus assembles various parts on the upper surface of the work 100. In FIG. 2, the outline arrows indicate the direction and position of the assembling load applied to the mover unit 10 when the work 100 is assembled. That is, the assembling load Fm is applied downward along the center line of the magnet portion 12. The assembling load Fm[N] is calculated by the following equation (1) in consideration of the load due to the moment.
Fm=F+Co(F×Lr)/Ma+Co((F^2)×Lp)/Ma (1)

Here, F[N] is a load applied to the mover unit 10, Co[N] is a static rated load, Lr[m] is a load position in the rolling direction, Lp[m] is a load position in the pitching direction, and Ma[Nm. ] Represents the static allowable moment in the pitching direction.

Since the load position Lr in the rolling direction is 0, a moment corresponding to the load position Lp in the pitching direction is applied to the mover unit 10. Two guide rails 31 are arranged in parallel on the wall portions 30A and 30B of the frame 30, and the distances to the positions where the assembling load is applied are equal. For this reason, the load from the mover unit 10 is applied to the wall portions 30A and 30B of the frame 30 through the slider 13 and the guide rail 31 in the same magnitude in the left and right opposite directions.

Therefore, even when the walls 30A and 30B of the frame 30 are deformed by the load from the mover unit 10, the amounts of deformation of the walls 30A and 30B of the frame 30 are substantially the same. Since the deformation direction is the opposite direction, the distance between the exciting core 22 fixed to the wall portion 30A and the magnet portion 12 and the distance between the exciting core 22 fixed to the wall portion 30B and the magnet portion 12 similarly change. To do. Accordingly, the displacement of the mover unit 10 in the left-right direction (Y direction) during assembly is suppressed, and the positioning accuracy of the mover unit 10 can be maintained.

Note that there is a possibility that initial deformation will occur in the frame 30 at the start of assembly to the work 100. The initial deformation amount of the frame 30 can be reduced by, for example, teaching a robot of an assembling apparatus and preloading the frame 30.

FIG. 3 is a diagram for explaining the heat transfer structure according to the present embodiment. FIG. 3 is a cross-sectional view of the linear motor, and shows the configuration of the right half with respect to the dashed-dotted line in FIG. In FIG. 3, white arrows indicate heat transfer paths. Here, heat transfer from the coil unit 33 of the wall portion 30B will be described, but the same applies to heat transfer from the coil unit 33 of the other wall portion 30A. Note that the numerical values and materials in the following description are merely examples, and are not intended to limit the scope of the present invention.

The heat generated in the coil 21 is transmitted to the exciting core 22 and further to the fixing screw 24 and the heat transfer material 25. As described above, since the heat insulating spacer 23 is arranged on the head of the fixing screw 24, heat transfer from the head of the fixing screw 24 to the wall portion 30B of the frame 30 is suppressed. Further, since the air layer is provided around the body of the fixing screw 24, heat transfer from the body of the fixing screw 24 to the wall 30B of the frame 30 is suppressed.

In the gap between the heat transfer material 25 and the wall portion 30B of the frame 30, a heat insulating material that suppresses heat transfer from the surface of the heat transfer material 25 or a heat insulating layer 32 filled with air is provided. The heat insulating layer 32 suppresses heat transfer from the heat transfer material 25 to the wall portion 30B of the frame 30. Therefore, the heat transferred to the heat transfer material 25 is further transferred to the heat dissipation plate 26 and is released from the heat dissipation plate 26 into the atmosphere.

The amount of temperature increase due to heat transfer from the coil 21 can be calculated from the amount of heat transfer and the thermal resistance of each member. The thermal resistance Rth [K/W] of each member is calculated by the following equation (2).
Rth=d/(λ×A) (2)

Here, d[m] is the thickness of the member (length of heat conduction), λ[w/(m·k)] is the thermal conductivity of the member, and A[m ² ] is the cross-sectional area of the member. Is represented. The temperature rise amount of each member reaches a value obtained by multiplying the heat transfer amount by the thermal resistance after a sufficient time has elapsed.

The relationship between the amount of temperature rise and the elongation of the member due to thermal expansion is expressed by the following equation (3).
ΔT=ΔL/(L×α) (3)

Here, ΔL[m] is the elongation of the member due to thermal expansion, α[/K] is the linear expansion coefficient of the member, ΔT[K] is the temperature difference before and after the temperature rise, and L[m] is the member's It represents the length.

The wall portion 30B of the frame 30 is formed of, for example, a casting having a linear expansion coefficient (linear expansion coefficient) α of 10.5×10 ⁻⁶ [/K]. The size of the wall portion 30B of the frame 30 is, for example, 44 mm in the vertical direction (Z direction) and 181 mm in the horizontal direction (X direction). The wall portion 30B of the frame 30 has a thickness (heat transfer length) L of, for example, 30 mm. If the expansion ΔL in the thickness direction of the wall portion 30B of the frame 30 is to be suppressed to several microns or less with such a design value, it is necessary to suppress the temperature difference ΔT to 5K or less from the equation (1).

Next, heat transfer from the excitation core 22 in the Y direction will be described. As shown in FIG. 3, the heat of the excitation core 22 is transferred in the direction (Y direction) perpendicular to the side surface of the excitation core 22. The size of the side surface of the exciting core 22 is, for example, 30 mm in length (Z direction) and 150 mm in width (X direction).

The heat transfer material 25 is connected to the side surface of the excitation core 22 and is made of, for example, copper having a thermal conductivity of 398 [W/(m·k)]. The shape of the heat transfer material 25 is, for example, a cylinder having a radius of 6 mm and a length of 40 mm. The thermal resistance of the heat transfer material 25 is 0.44 [K/W] according to the equation (2).

The heat dissipation plate 26 has a high degree of freedom in design because it is relatively easy to secure the surface area and the cross-sectional area as described above. The heat resistance of the heat dissipation plate 26 is designed to be, for example, 0.32 [K/W] so that heat can be efficiently transferred from the heat transfer material 25. The combined thermal resistance of the heat transfer material 25 and the heat dissipation plate 26 is approximated by 0.76 (=0.44+0.32) [K/W].

The heat insulating spacer 23 is formed of, for example, a polyacetal resin having a thermal conductivity of 0.25 [w/(m·K)]. The shape of the heat insulating spacer 23 is, for example, a ring shape having an outer diameter of 10 mm, an inner diameter of 4.3 mm, and a thickness of 5 mm. For example, six heat insulating spacers 23 are arranged on the exciting core 22. The thermal resistance of the heat insulating spacer 23 is 312 [K/W] according to the equation (2). The other space adjacent to the exciting core 22 is filled with air having a thermal conductivity of 0.024 [w/(m·K)], and the space between the exciting core 22 and the wall portion 30B of the frame. The thermal resistance of is from equation (2) to be 47.4 [K/W].

As described above, the ease with which heat is transmitted through the heat transfer material 25 and the heat dissipation plate 26 is about 60 times that of air and about 410 times that of the heat insulating spacer 23. Therefore, most of the heat of the excitation core 22 is transferred to the heat transfer material 25 and the heat dissipation plate 26.

Next, heat transfer in the XZ plane direction in the heat transfer material 25 will be described. The diameter of the through hole 29 is, for example, 22 mm, and the heat transfer material 25 is arranged at the center of the through hole 29. That is, the central axes of the heat transfer material 25 and the through hole 29 coincide with each other. The thickness of the heat insulating layer 32 between the heat transfer material 25 and the through hole 29 is, for example, 5 mm (constant). The cross-sectional area A of heat transfer in the XZ plane direction is equal to the circumferential surface area of the heat transfer material 25, and the thermal resistance of the heat insulating layer 32 in the XZ plane direction is 176 [K/W] according to the equation (2). .. As described above, since the heat insulating layer 32 has a thermal resistance about 400 times that of the heat transfer material 25, most of the heat of the heat transfer material 25 is transferred to the Y direction, that is, the heat dissipation plate 26.

According to this embodiment, the frame 30 of the stator unit 20 is provided with the through hole 29, and the heat generated from the coil unit 33 is transmitted to the heat transfer material 25 passed through the through hole 29. The heat transferred to the heat transfer material 25 is radiated from the heat dissipation plate 26 provided outside the frame 30. Since the heat insulating layer 32 prevents heat transfer from the heat transfer material 25 to the frame 30, the thermal expansion of the frame 30 is suppressed and the displacement of the guide rail 31 supported by the frame 30 is reduced. Accordingly, the displacement of the mover unit 10 on the guide rail 31 can be suppressed, and the positioning accuracy of the mover unit 10 can be improved. Further, the flatness of the upper surface of the work 100 held by the mover unit 10 can be favorably maintained, and a highly accurate assembling accuracy can be realized. In addition, the heat transfer material 25 is used to efficiently transfer heat to the heat dissipation plate 26, so that the heat insulating spacer 23 disposed between the coil unit 33 and the frame 30 can be made thin.

In a conventional linear motor, a cooling unit may be provided between the coil and the exciting core in order to remove heat generated in the coil. In such a case, the following problems may occur. That is, in order to improve the cooling efficiency, the refrigerant circulation unit is arranged at the end of the traveling path, and the refrigerant passages are arranged in parallel with the coil arrangement direction. However, if the linear motor is made longer, the flow path of the refrigerant becomes longer, and the heat exchange efficiency is reduced. On the contrary, if the heat exchange efficiency is to be maintained, lengthening is limited. Further, when the length of the linear motor is increased, it is necessary to increase the number of cooling units or increase the capacity, which increases the cost. Furthermore, since the distance between the permanent magnet driven by the coil and the guide rail becomes long, the moment applied to the guide rail increases. It is necessary to widen the width of the guide rail in order to increase the rigidity of the guide rail, but the moment increases further. According to the present embodiment, since it is not necessary to provide a cooling unit between the coil and the exciting core, such a problem can be avoided.

(Second embodiment)
Next, a linear motor according to the second embodiment of the present invention will be described. The stator unit 20 of the linear motor 2 according to the present embodiment is provided with one guide rail 31. For simplification of the description, differences from the first embodiment will be mainly described.

FIG. 4 is a sectional view of the linear motor 2 according to this embodiment. In the present embodiment, one guide rail 31 is provided on the upper surface of one wall portion 30A of the frame 30. The stator unit 20 has one guide rail 31 supported by the wall portion 30A of the frame 30. A slider 13 is provided on the lower end of the work holder 11, and the slider 13 is mounted on one guide rail 31. The work holder 11 holds the work 100 above the slider 13.

The dashed-dotted line in FIG. 4 represents the center line of the wall portion 30A of the frame 30. The center line of the wall portion 30A is a line that bisects the cross section of the wall portion 30A in the thickness direction. The centers of the guide rail 31 and the slider 13 in the width direction are located on the center line of the wall portion 30A. In the work holder 11, the work 100 is placed on the center line of the wall portion 30A, and the work 100 is assembled from above by a mounting device (not shown). The white arrows in FIG. 4 indicate the direction and position of the assembly load applied to the mover unit 10.

The assembling device is arranged so that the load from the mover unit 10 is applied to the center line of the wall portion 30A of the frame via one guide rail 31. As a result, the bending of the wall portion 30A of the frame 30 in the left-right direction (Y direction) during assembly is suppressed. The distance between the magnet portion 12 and the excitation core 22 is not significantly affected even when a load is applied to the frame 30. That is, the effect of suppressing an increase in the load in the width direction due to the displacement of the frame 30 can be obtained. Therefore, even when one guide rail 31 is adopted, high positioning accuracy can be obtained without increasing the width of the guide rail 31.

Through holes 29 are formed in the wall portions 30A and 30B of the frame 30 as in the first embodiment, and the heat transfer material 25 is passed through the through holes 29. One end of the heat transfer material 25 is connected to the coil unit 33, and the other end is connected to the heat dissipation plate 26. A heat insulating layer 32 is formed between the heat transfer material 25 and the through hole 29, and heat generated in the coil unit 33 is propagated to the heat dissipation plate 26 via the heat transfer material 25.

Also in this embodiment, the frame 30 of the stator unit 20 is provided with the through hole 29, and the heat generated from the coil unit 33 is transmitted to the heat transfer material 25 passed through the through hole 29. The heat transferred to the heat transfer material 25 is radiated from the heat dissipation plate 26 provided outside the frame 30. Since the heat insulating layer 32 prevents heat transfer from the heat transfer material 25 to the frame 30, the thermal expansion of the frame 30 is suppressed and the displacement of the guide rail 31 supported by the frame 30 is reduced. Accordingly, the displacement of the mover unit 10 on the guide rail 31 can be suppressed, and the positioning accuracy of the mover unit 10 can be improved. Also. The thickness (length in the Y direction) of the heat insulating spacer 23 can be reduced, and the lengths of the guide rail 31 and the magnet portion 12 can be shortened. As a result, the moment that can be generated in the mover unit 10 is reduced, and the rigidity required for one guide rail 31 is reduced.

(Third Embodiment)
Next, a linear motor according to the third embodiment of the present invention will be described. The stator unit 20 of the linear motor 3 according to this embodiment is provided with a coil unit 33 including three coils 21. For simplification of the description, differences from the first embodiment will be mainly described.

FIG. 5 is a side view of the linear motor 3 according to this embodiment. The linear motor 3 includes a plurality of stator units 20A to 20F. Each coil unit 33 of the stator units 20A to 20F has three coils 21. The three coils 21 configure three phases of UVW phase, respectively, and are connected to one three-phase AC power system. That is, the coil unit 33 constitutes the minimum unit of the UVW-phase power system. The coil units 33 of the stator units 20A to 20F are independently controlled. In each stator unit of FIG. 5, the heat dissipation plate 26 is not shown.

In addition, each of the stator units 20A to 20F has one encoder 27. For example, in FIG. 5, the linear scale 14 of the mover unit 10 is detected only by the read head 27a of the stator unit 20C. That is, in FIG. 5, the linear scale 14 of the mover unit 10 is not detected by the read heads 27a of the stator units 20B and 20D on both sides of the stator unit 20C. On the side surface (XZ plane) of each stator unit, the encoder 27 is arranged corresponding to the V-phase coil 21, and the heat transfer material 25 is arranged corresponding to the U-phase and W-phase coil 21. .. With such an arrangement, heat generated in the coil unit 33 can be transferred to the front in the Y direction, that is, to the outside of the encoder 27 when viewed from the coil unit 33, without the heat transfer material 25 and the encoder 27 interfering with each other. it can.

As shown in FIG. 5, it is assumed that the mover unit 10 is located near the center of the stator unit 20C. At this time, in order to prevent the magnet unit 12 from being driven and controlled by the stator unit 20B and the stator unit 20D, it is desirable that the linear scale 14 is not detected by the plurality of encoders 27 at the same time. Therefore, in the present embodiment, the encoder 27 and the linear scale 14 are configured such that the one linear scale 14 is positioned with respect to the one encoder 27. The stator unit 20 is composed of a coil unit 33 composed of a set of three-phase coils 21, and each coil unit 33 is independently controlled. Therefore, it is possible to prevent the mover unit 10 from being driven simultaneously by the two adjacent stator units 20, and it is possible to arrange the plurality of mover units 10 in high density.

(Fourth Embodiment)
Next, a method for manufacturing an article using the linear motor according to the above embodiment will be described. The article is manufactured by a manufacturing line including a transport device and a plurality of assembling devices. The transfer device is configured using the linear motor according to the above-described embodiment. Hereinafter, the linear motor 1 according to the first embodiment will be described as an example. In the present embodiment, the article is a product obtained by assembling the work 100.

The linear motor 1 is provided along the manufacturing line and sequentially conveys the work 100 to a plurality of assembling devices. The work 100 is held by the work holder 11 of the mover unit 10. First, the linear motor 1 moves the mover unit 10 to the first assembly device. The linear motor 1 stops the mover unit 10 at a predetermined position based on the position information of the mover unit 10 acquired from the encoder 27. The first assembling apparatus performs a first assembling process on the work 100.

After the completion of the first assembling process, the linear motor 1 moves the mover unit 10 to the second assembling device. The linear motor 1 stops the mover unit 10 at a predetermined position based on the position information of the mover unit 10 acquired from the encoder 27. The second assembling apparatus performs the second assembling process on the work 100. In this way, the linear motor 1 sequentially conveys the work 100 to the assembling device, and the assembling device assembles the work 100, so that the product can be finally obtained.

(Other embodiments)
The present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention. For example, the number of the through holes 29 provided in the frame 30 of the stator unit 20 and the number of the heat transfer materials 25 passed through the through holes 29 are not limited. The through holes 29 and the heat transfer material 25 may be provided in the wall portions 30A and 30B of the frame 30 in an amount of 1 to 4 or more, respectively. Further, the through holes 29 and the heat transfer material 25 may be provided side by side in the vertical direction on the wall portions 30A and 30B of the frame 30.

1 linear motor 10 mover unit 12 magnet part 23 heat insulating spacer (heat insulating part)
25 Heat transfer material (heat transfer member)
26 Heat sink (heat sink)
29 Through Hole 30 Frame 30A, 30B Wall 31 Guide Rail 32 Heat Insulation Layer 33 Coil Unit

Claims (13)

A guide rail in which a mover unit having a permanent magnet can move,
A frame supporting the guide rail and connected to the coil unit,
A heat insulating member provided between the coil unit and the frame,
A heat transfer member having one end connected to the coil unit and the other end connected to the heat dissipation portion,
The frame has a wall portion extending along the guide rail, a through hole through which the heat transfer member penetrates is formed in the wall portion, and heat insulation is provided between the through hole and the heat transfer member. A linear motor characterized in that layers are provided. The linear motor according to claim 1, wherein a diameter of the through hole is smaller than a thickness of the wall portion. The frame further has another wall portion facing the wall portion,
The linear motor according to claim 2, wherein a through hole is formed at a position of the other wall portion facing the through hole of the wall portion. The linear motor according to claim 1, wherein the heat insulating layer has a thermal resistance larger than a thermal resistance of the heat transfer member. The linear motor according to any one of claims 2 to 4, wherein an opening area of the through hole is 5 to 10% or less of an area of the wall portion. The linear motor according to any one of claims 1 to 5, wherein the through hole has an elliptical shape having a long diameter in the vertical direction with respect to the guide rail. The heat dissipation part has a plate shape facing the wall part, and a length of the heat dissipation part in a direction along the guide rail is shorter than a length of the frame in a direction along the guide rail. The linear motor according to any one of claims 1 to 6. The guide rail is supported by the wall portion, and a load from the mover unit is applied to the center line in the thickness direction of the wall portion via the guide rail. The linear motor described in 2. The linear motor according to claim 1, further comprising a detection unit that detects a position of the mover unit, the detection unit being thermally insulated from the frame. The linear motor according to claim 9, wherein the detection unit is disposed between the heat dissipation unit and the wall unit. The linear motor according to claim 9 or 10, wherein the coil unit includes a set of U-phase, V-phase, and W-phase coils. The heat transfer member is provided corresponding to each of the U-phase coil and the W-phase coil, and the detection unit is disposed corresponding to the V-phase coil. Linear motor. A method for manufacturing an article using the linear motor according to claim 1.
A step of transporting the work held by the mover unit to an assembly device by moving the mover unit;
And a step of assembling the work with the assembling device to produce an article.

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