Manufacturing method for heat dissipation structures
The described method of forming and welding metal fins on a flexible plate to create a cylindrical heat dissipation structure addresses the need for efficient and cost-effective heat dissipation with high thermal conductivity and mechanical strength, suitable for electric motors.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NHK SPRING CO LTD
- Filing Date
- 2023-12-11
- Publication Date
- 2026-06-02
AI Technical Summary
Existing heat dissipation structures for electric motors are either costly or lack mechanical strength, and there is a need for a more efficient and cost-effective manufacturing method that maintains high thermal conductivity and mechanical integrity.
A method involving forming metal fins on a flexible belt-shaped metal plate, deforming it into a cylindrical shape with the fins extending outward, and joining both ends by welding, utilizing materials like aluminum alloys for high thermal conductivity and mechanical strength.
The resulting heat dissipation structure achieves high cooling efficiency, mechanical strength, and cost-effectiveness by integrating fins with the housing, enabling efficient heat transfer and reducing manufacturing costs through mold-less processes.
Smart Images
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Abstract
Description
Technical Field
[0001] One embodiment of the present invention relates to a heat dissipation structure having a cooling function and a method for manufacturing the same.
Background Art
[0002] Electric motors such as motors, inverters, pumps, and compressors generate heat during operation. Therefore, heat dissipation fins may be attached to the case that houses the electric motor. For example, Patent Document 1 discloses a cylindrical electric motor case provided with a plurality of fins. This electric motor case is manufactured by extrusion molding or die casting of aluminum.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] One embodiment of the present invention aims to provide a heat dissipation structure having a novel structure and a method for manufacturing the same. Alternatively, one embodiment of the present invention aims to provide a heat dissipation structure having high mechanical strength and a method for manufacturing the heat dissipation structure at low cost.
Means for Solving the Problems
[0005] One embodiment of the present invention is a method for manufacturing a heat dissipation structure. This method includes forming a plurality of metal fins on a flexible belt-shaped metal plate, deforming the plate so that the plate forms a cylindrical shape and the fins extend outward from the plate, and joining both ends of the plate by welding.
Brief Description of the Drawings
[0006] [Figure 1] A schematic perspective view of a heat dissipation structure according to an embodiment of the present invention. [Figure 2] A schematic top view of a heat dissipation structure according to an embodiment of the present invention. [Figure 3] A schematic perspective view of a heat dissipation structure according to an embodiment of the present invention. [Figure 4] A schematic perspective view of a heat dissipation structure according to an embodiment of the present invention. [Figure 5A] A schematic perspective view of a heat dissipation structure according to an embodiment of the present invention. [Figure 5B] A schematic perspective view of a heat dissipation structure according to an embodiment of the present invention. [Figure 6A] A schematic perspective view of a heat dissipation structure according to an embodiment of the present invention. [Figure 6B] A schematic perspective view of a heat dissipation structure according to an embodiment of the present invention. [Figure 7] A schematic side view of a heat dissipation structure according to an embodiment of the present invention. [Figure 8A] A schematic perspective view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 8B] A schematic side view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 8C] A schematic side view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 9] A schematic diagram showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 10A] A schematic side view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 10B] A schematic side view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 11A] A schematic side view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 11B] A schematic side view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 12A] A schematic perspective view showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention. [Figure 12B]Schematic diagram showing a method for manufacturing a heat dissipation structure according to an embodiment of the present invention.
Embodiments for Carrying Out the Invention
[0007] Hereinafter, each embodiment of the invention disclosed in this application will be described with reference to the drawings. However, the present invention can be implemented in various forms without departing from the gist thereof, and is not to be construed as being limited to the description of the embodiments exemplified below.
[0008] The drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect for clearer explanation, but this is merely an example and does not limit the interpretation of the present invention. Also, in this specification and each figure, elements having the same functions as those described for the already shown figures may be given the same reference numerals, and duplicate explanations may be omitted.
[0009] Hereinafter, a heat dissipation structure 100, which is one of the embodiments of the present invention, and its manufacturing method will be described.
[0010] 1. Structure of the heat dissipation structure FIG. 1 and FIG. 2 respectively show a schematic perspective view and a top view of the heat dissipation structure 100. The heat dissipation structure 100 includes a metal housing 102 having a cylindrical shape, and a plurality of metal fins 104 provided on the outer periphery (outer wall) of the housing 102 and extending radially from the housing 102. Various electric motors are housed inside the housing 102. Although not shown, a flow path for refluxing a refrigerant for cooling the heat dissipation structure 100 may be provided outside or inside the heat dissipation structure 100. Hereinafter, in each drawing, the direction in which the axis of the cylindrical shape of the housing 102 extends is taken as the z direction, and the directions perpendicular to the z direction and orthogonal to each other are taken as the x direction and the y direction.
[0011] The size of the housing 102 (outer diameter of the cylindrical shape and length in the z direction) is appropriately selected depending on the type and size of the electric motor. For example, the outer diameter may be between 200 mm and 500 mm, and the length in the z direction may be between 30 mm and 300 mm. The aspect ratio (outer diameter / length) of the housing 102 may be between 1 and 20. The thickness of the housing 102 (half the difference between the outer diameter and inner diameter) is also selected according to the strength required of the heat dissipation structure 100, for example, from a range of 1 mm to 20 mm. The thickness, height (length perpendicular to the z direction from the outer wall of the housing 102), and spacing of the fins 104 are also appropriately selected according to the cooling efficiency required of the heat dissipation structure 100 and the number of fins 104, for example, the thickness may be selected from a range of 0.5 mm to 5 mm, the height from 30 mm to 90 mm, and the spacing from 1 mm to 20 mm.
[0012] As shown in FIGS. 1 and 2, the fins 104 may be arranged at equal intervals over the entire outer wall of the housing 102, or as shown in FIG. 3, may be arranged on a part of the outer periphery of the housing 102. In this case, one or more openings 102a for wiring and flow paths may be provided in the portion where the fins 104 are not provided. The length of the fins 104 in the z direction may be the same as the length of the housing 102 (FIG. 3), or may be smaller than the length of the housing 102 (FIG. 4). Further, the fins 104 may be arranged such that their main surfaces (surfaces having the maximum area) 104a are parallel to the z direction which is the axis of the housing 102, or as shown in FIG. 5A, the main surfaces 104a may be arranged to be inclined from the z direction. Alternatively, as shown in FIG. 5B, a plurality of fins 104 may be arranged to form a plurality of rows on the outer wall of the housing 102. Although not shown, the fins 104 may form a staggered arrangement on the outer wall of the housing 102. Note that the shape of each fin 104 is not limited to a hexahedron in which the main surface 104a is a quadrilateral. For example, as shown in FIG. 6A, each fin 104 may have a main surface 104a whose contour is formed by a straight line and a curve or only a curve, or as shown in FIG. 6B, may have a bent main surface 104a. Alternatively, as shown in FIG. 7, each fin 104 may have a branched structure. Thus, considering the cooling efficiency required for the heat dissipation structure 100, various shapes and arrangements can be selected.
[0013] The housing 102 and the fins 104 may have different compositions or the same composition. Examples of materials included in the housing 102 and fins 104 include metals and their alloys such as aluminum, iron, and titanium, but preferably, lightweight aluminum alloys with high thermal conductivity are used. Examples of aluminum alloys include alloys containing aluminum, zinc, magnesium, and copper, such as A7072, A7050, A7075, and A7N01, and alloys of aluminum and magnesium containing silicon, such as A6061, A6063, and A6N01. However, the aluminum alloy is not limited to the above alloys, and alloys of aluminum and magnesium, such as A5052, A5056, A5083, and A5454, silicon-added aluminum, such as A4032 and A4043, and alloys of aluminum and manganese, such as A3003, A3005, and A3105 may also be used. By using aluminum alloy for the housing 102 and fins 104, the heat dissipation structure 100 can exhibit high heat dissipation characteristics due to the high thermal conductivity of aluminum.
[0014] 2. Method for manufacturing a heat dissipation structure The manufacturing method for the heat dissipation structure 100 will be described below.
[0015] First, as shown in Figure 8A, fins 104 are formed on a belt-shaped plate 106 that will become the housing 102. For example, the fins 104 can be placed on the upper surface of the plate 106, and thermal energy can be supplied to the surfaces in contact with each other by laser irradiation, arc discharge, electron beam irradiation, etc., to weld them together (Figure 8B). As the laser light, for example, a yttrium-aluminum-garnet (YAG) laser with a wavelength of 1064 nm or a fiber laser with a wavelength of 1070 nm can be used. Alternatively, a laser beam processed into a linear shape using an optical element may be used. Or, as shown in Figure 8C, the fins 104 can be formed by skiving the plate 106. That is, a part of the surface of the plate 106 can be peeled off using a cutting jig 108, and the peeled portion can be raised from the plate 106 to form the fins 104.
[0016] After the fins 104 are formed, the plate 106 is wound and deformed as shown in Figure 9. Specifically, the plate 106 is deformed so that it forms a cylindrical shape and the fins 104 extend radially outward from the plate 106. At this time, a core material 110 may be used as a support jig to correctly deform the plate 106 into a cylindrical shape. That is, as shown in Figure 9, a cylindrical core material 110 may be placed on the bottom surface of the plate 106 (the surface opposite to the surface where the fins 104 are formed), and the plate 106 may be wound around the core material 110. In addition, a groove 110a extending in the z direction may be provided in a part of the core material 110 to secure space for welding from the bottom side, which will be described later. In this case, the plate 106 is deformed so that both ends of the plate 106 overlap with the groove 110a.
[0017] Furthermore, as shown in Figure 10A, a gear-shaped forming roller 120 may be used when winding the plate 106. The forming roller 120 has a cylindrical rod 120a and a plurality of plate-shaped teeth 120b, and the plurality of teeth 120b are arranged on the outer surface of the rod 120a at the same pitch as the fins 104 or at a larger pitch than the fins 104. By rotating the forming roller 120 with the forming roller 120 positioned so that the teeth 120b mesh with the fins 104, the plate 106 can be pressed and bent into a cylindrical shape. At this time, the plate 106 may be placed on the core material 110, and the core material 110 may be rotated in the opposite direction to the rotation direction of the forming roller 120. If the teeth 120b interfere with the fins 104, the forming roller 120 may be reversibly moved so that the teeth 120b can be in contact with the plate 106 and separated from the plate 106 (see straight arrow). If the pitch of the fins 104 is too narrow and the molding roller 120 cannot rotate, the molding roller 120 may not rotate, but instead be moved linearly and reversibly as shown by the straight arrow to apply pressure to the plate 106 and deform it. In this case, the molding roller 120 does not have to be cylindrical; it may be plate-shaped.
[0018] If the fins 104 are provided on a portion of the outer circumference of the housing 102, the plate 106 may be deformed by rotating a cylindrical molding roller 122 that does not have teeth 120b (i.e., has substantially no irregularities on its outer circumference) and temporarily pressing it against the portion of the plate 106 where the adjacent fins 104 are widely spaced (see Figure 10B). For example, as shown in Figure 3, if there is sufficient space between adjacent fins 104 in the xy plane, the molding roller 122 may be pressed against that portion. Alternatively, as shown in Figure 4, the molding roller 122 may be pressed against the portion of the outer circumference of the housing 102 that does not overlap with the fins 104 in the xy plane. Furthermore, the plate 106 may be deformed by simultaneously using both the molding roller 120 with teeth 120b and the molding roller 122 without teeth 120b.
[0019] Subsequently, the heat dissipation structure 100 can be manufactured by joining the ends of the plate 106 together. Joining methods include friction stir welding, diffusion welding, and welding. When joining by welding, thermal energy can be supplied from the outside (the side where the fins 104 are placed) or the inside (the side opposite to the side where the fins 104 are placed) of the plate 106 using laser light, arc discharge, electron beam, etc. As shown in the enlarged view of a part of Figure 9 (Figure 11A), interlocking steps 106a may be provided at both ends of the plate 106 to secure a wider contact surface during welding. There are no restrictions on the shape of the steps 106a; the steps 106a should be provided such that when the steps 106a are interlocked, the surfaces that contact each other at both ends extend in the circumferential direction and the z direction of the housing 102. For example, as shown in Figure 11A, the steps 106a can be formed by removing a part of the top surface at one end of the plate 106 and a part of the bottom surface at the other end. In this case, the thickness of both ends is adjusted so that its sum is the same as or substantially the same as the thickness of plate 106. If a step 106a is provided, the ends may be joined using a fixing jig 112 consisting of a combination of bolts, screws, nuts, etc. (see Figure 11B). Alternatively, the ends may be joined by diffusion bonding by applying pressure in a direction perpendicular to the z direction while the ends are in contact.
[0020] If the thickness of the fin 104 is small, the fin 104 may deform due to the force applied when the plate 106 deforms. For this reason, after joining both ends, the deformed fin 104 may be corrected to restore its shape to that of the plate 106 before deformation.
[0021] Alternatively, an auxiliary member 114 may be used to protect the fins 104 and prevent deformation when the plate 106 deforms. As shown in Figure 12A, the auxiliary member 114 has a flexible belt 116 and a plurality of flexible protective walls 118 provided on the belt 116, and the protective walls 118 can be arranged on the fins 104 so that the fins 104 and protective walls 118 alternate, that is, each fin 104 is sandwiched between adjacent protective walls 118 (Figure 12B). The belt 116 and protective walls 118 are made of materials such as silicone resin, vinyl chloride resin, polystyrene resin, polyurethane resin, ethylene-polyvinyl biacetate resin, or rubber such as styrene-butadiene rubber, ethylene-propylene rubber, or epichlorohydrin rubber. This makes the belt 116 and protective walls 118 flexible and allows for elastic deformation. Therefore, by positioning the auxiliary member 114 so that the fin 104 and the protective wall 118 interlock, and deforming the plate 106 in this state, even if the force required for deformation is applied to the fin 104, that force can be reduced. As a result, deformation of the fin 104 can be prevented. Preferably, the protective wall 118 is provided such that its height is greater than the height of the fin 104. This more effectively prevents the force applied during deformation from being applied to the fin 104, and the force can be selectively used for the deformation of the plate 106.
[0022] As described above, the heat dissipation structure 100 according to the embodiment of the present invention includes an aluminum alloy such as A7075 or A6061. Therefore, the heat dissipation structure 100 not only achieves high cooling efficiency due to the high thermal conductivity of aluminum, but is also lightweight and strong. This makes it possible to apply it to heat dissipation structures that require high reliability, such as motors for generating thrust in aircraft. Furthermore, the heat dissipation structure 100 according to this embodiment can be suitably used as a heat dissipation structure for various vehicles such as drones and electric vehicles, where weight reduction is required.
[0023] Furthermore, in the manufacturing method of the heat dissipation structure 100 according to the embodiment of the present invention, the fins 104 are formed by welding or skiving. As a result, the housing 102 and the fins 104 are integrated, and the heat generated by the electric motor can be efficiently transferred from the housing 102 to the fins 104, thus enabling highly efficient cooling of the electric motor. Moreover, compared to extrusion molding and mold processing, since molds and templates are not required, the manufacturing cost is low, and it is possible to provide fins 104 with a large height at high density, i.e., at a narrow pitch. In addition, in this manufacturing method, the cutting process is limited to the formation of steps at both ends of the plate 106, resulting in high material utilization efficiency. This means that a heat dissipation structure can be provided at a low cost by applying this manufacturing method.
[0024] The embodiments described above as examples of the present invention can be combined and implemented as appropriate, insofar as they do not contradict each other. Furthermore, any additions, deletions, or design modifications made by those skilled in the art based on these embodiments are also included within the scope of the present invention, as long as they retain the essence of the present invention.
[0025] Furthermore, any effects or benefits other than those brought about by the embodiments described above, if they are clear from the description herein or easily predictable to those skilled in the art, are naturally understood to be brought about by the present invention. [Explanation of symbols]
[0026] 100: Heat dissipation structure, 102: Housing, 102a: Opening, 104: Fin, 104a: Main surface, 106: Plate, 106a: Step, 108: Cutting jig, 110: Core material, 110a: Groove, 112: Fixing jig, 114: Auxiliary member, 116: Belt, 118: Protective wall, 120: Forming roller, 120a: Rod, 120b: Teeth, 122: Forming roller
Claims
1. Forming multiple metal fins on a flexible, belt-shaped metal plate, Deforming the plate such that it forms a cylindrical shape and the fins extend outward from the plate, This includes joining both ends of the aforementioned plate by welding, A method for manufacturing a heat dissipation structure in which the plate and the fins have the same composition and each contains aluminum, zinc, magnesium, and copper.
2. The method according to claim 1, wherein the formation of the fins is performed by joining the fins to the plate by welding.
3. The method according to claim 1, wherein the formation of the fins is carried out by skiving the plate.
4. The method according to claim 1, wherein the welding is performed by irradiating the cylindrical shape with laser light from the outside.
5. The method according to claim 1, wherein the welding is performed by supplying thermal energy from the inside of the cylindrical shape.
6. The method according to claim 1, further comprising forming interlocking steps at both ends of the plate.
7. The deformation of the plate is performed with an auxiliary member placed on the plate. The auxiliary member comprises a flexible belt and a plurality of flexible protective walls arranged on the flexible belt. The method according to claim 1, wherein the protective wall is arranged alternately with the plate when the auxiliary member is positioned such that the fin and the protective wall are sandwiched between the plate and the belt.
8. The method according to claim 7, wherein the belt and the protective wall include resin or rubber.