Connected body and rotating motor

Abstract

The invention comprises: a first component, which is composed of a pressed powder molded body of soft magnetic powder; a second component which is separate from the first component; and a self-tapping screw, which penetrates the second component and reaches the first component to connect the first component and the second component, wherein at least the first component of the first component and the second component has a lower hole for the teeth of the self-tapping screw to bite into, the inner diameter of the lower hole is not less than 83% and not more than 95% of the diameter of the teeth of the self-tapping screw and is larger than the diameter of the root of the teeth of the self-tapping screw, and has a spiral gap surrounded by the outer peripheral surface of the self-tapping screw and the inner peripheral surface of the lower hole.

Description

Technical Field

[0001] The present invention relates to a connection body and a rotating electric machine.

[0002] This application claims the benefit of priority based on Japanese Patent Application No. 2019-089192 filed on May 9, 2019, and all the contents described in the above-mentioned Japanese application are incorporated herein by reference. Background Art

[0003] As a rotating electrical machine such as a motor and a generator, an axial gap type rotating electrical machine is disclosed in Patent Document 1, wherein a rotor and a stator are arranged opposite to each other in a direction along the rotating axis of the rotor. The stator used in the rotating electrical machine has an armature core having a back yoke and a plurality of teeth, and a coil arranged on each tooth.

[0004] The iron core of Patent Document 1 is a connected body formed by connecting the teeth and yoke parts which are made separately from each other. More specifically, the iron core is made by fitting the columnar protrusions of the teeth and the recesses of the yoke parts. In Patent Document 1, the yoke part is made of laminated steel plates, and the teeth part is made of a powder compact, i.e., a powder core.

[0005] Patent Document 1: International Publication No. 2007 / 114079 Summary of the invention

[0006] The connecting body of the present invention has:

[0007] A first component, which is composed of a powder compact of soft magnetic powder;

[0008] a second component separate from the first component; and

[0009] A self-tapping screw penetrates the second member and reaches the first member to connect the first member and the second member.

[0010] At least the first component of the first component and the second component has a lower hole for the thread of the self-tapping screw to bite into,

[0011] The inner diameter of the lower hole is not less than 83% and not more than 95% of the diameter of the thread of the self-tapping screw, and is larger than the diameter of the thread bottom of the self-tapping screw.

[0012] A spiral gap is provided which is surrounded by the outer peripheral surface of the self-tapping screw and the inner peripheral surface of the lower hole.

[0013] The rotating electric machine of the present invention is an axial gap type rotating electric machine in which a rotor and a stator are arranged in the axial direction of the rotating shaft of the rotor.

[0014] This rotating electrical machine includes the connected body of the present invention.

[0015] Here, the connected body of the present invention is any of the following.

[0016] (1) The first member is a tooth portion used in an iron core of a rotating electrical machine, and the second member is a yoke portion used in the iron core, that is, a connected body of the present invention.

[0017] (2) The first member is a tooth portion used in an iron core of a rotating electrical machine, and the second member is a flange portion provided at an end of the tooth portion, that is, a connection body of the present invention.

[0018] (3) The first member is an iron core having a tooth portion and a yoke portion and used in a rotating electrical machine, and the second member is a housing for housing the iron core, that is, the coupled body of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a partial longitudinal sectional view of the axial gap type rotating electrical machine shown in the first embodiment.

[0020] Figure 2 This is a schematic perspective view of an iron core of a stator included in the axial gap type rotating electrical machine shown in the first embodiment.

[0021] Figure 3 Viewed from the side opposite to the side where the teeth are installed Figure 2 A schematic perspective view of a portion of an iron core.

[0022] Figure 4 yes Figure 2 A partial cross-sectional view of the iron core along the axial direction of the self-tapping screw.

[0023] Figure 5 Yes Figure 4 An enlarged partial view of a portion of the image.

[0024] Figure 6 This is a diagram showing a photograph of a cross section of the iron core according to the first embodiment along the axial direction of the tapping screw.

[0025] Figure 7 It is a partial longitudinal sectional view of the axial gap type rotating electrical machine shown in the second embodiment.

[0026] Figure 8 It is a partial longitudinal sectional view of the axial gap type rotating electrical machine shown in the third embodiment.

[0027] Fig. 9 It is a partial longitudinal sectional view of the axial gap type rotating electrical machine shown in the fourth embodiment. DETAILED DESCRIPTION

[0028] [Problems to be Solved by the Invention]

[0029] In the structure of Patent Document 1, the tooth portion is pressed into the recess of the yoke portion or the tooth portion is fixed to the recess of the yoke portion by an adhesive. However, the fixing of the tooth portion by pressing and the fixing of the tooth portion by an adhesive are complicated. Therefore, a connection body connected by a simpler structure is required.

[0030] One object of the present invention is to provide a connected body that is connected with a simple structure and has excellent productivity. Another object of the present invention is to provide a rotating electric machine having the connected body.

[0031] [Effects of the Invention]

[0032] The coupled body of the present invention has excellent productivity. In addition, the rotating electrical machine of the present invention has excellent productivity.

[0033] [Description of Embodiments of the Invention]

[0034] The present inventors have studied a structure for fixing the teeth and yoke of a powder compact by screws. Since the powder compact is brittle, screws are usually not used when fixing the powder compact to other components. The reason is that cracks may occur in the powder compact when screw holes are machined in the powder compact and when screws are installed in the screw holes. The present inventors have conducted research and found a structure that can solve the above-mentioned problem. Specifically, the first component and the second component are connected by a self-tapping screw, and the size of the lower hole for installing the self-tapping screw is optimized according to the size of the self-tapping screw, thereby solving the above-mentioned problem.

[0035] Hereinafter, embodiments of the present invention will be described by way of examples.

[0036] <1> A connected body according to an embodiment has:

[0037] A first component, which is composed of a powder compact of soft magnetic powder;

[0038] a second component separate from the first component; and

[0039] A self-tapping screw penetrates the second member and reaches the first member to connect the first member and the second member.

[0040] At least the first component among the first component and the second component has a lower hole for the thread of the self-tapping screw to bite into,

[0041] The inner diameter of the lower hole is not less than 83% and not more than 95% of the diameter of the thread of the self-tapping screw and is larger than the diameter of the thread bottom of the self-tapping screw.

[0042] A spiral gap is provided which is surrounded by the outer peripheral surface of the self-tapping screw and the inner peripheral surface of the lower hole.

[0043] The above-mentioned connection body can be manufactured by simply fixing the first component and the second component with a tapping screw. Compared with fixing by pressing or fixing with an adhesive, fixing with a tapping screw is easier. Therefore, the productivity of the above-mentioned connection body is excellent.

[0044] In the above-mentioned connection body, the inner diameter of the lower hole for installing the self-tapping screw is more than 83% of the diameter of the self-tapping screw's teeth, and is larger than the diameter of the self-tapping screw's tooth bottom. If the inner diameter of the lower hole is more than 83% of the diameter of the self-tapping screw's teeth, the excessive stress caused by the self-tapping screw's teeth is suppressed from acting on the lower hole. In addition, if the inner diameter of the lower hole is larger than the diameter of the self-tapping screw's tooth bottom, the shaft of the self-tapping screw will not press and expand the lower hole radially outward. Therefore, the connection body involved in the embodiment is not prone to cracking and other problems. In addition, if the inner diameter of the lower hole is less than 95% of the diameter of the self-tapping screw's teeth, the self-tapping screw is not easy to loosen, and the first component and the second component can be firmly fixed.

[0045] <2> As one aspect of the connected body according to the embodiment, the following aspects are given:

[0046] The second component is composed of a powder compact of soft magnetic powder.

[0047] The lower hole is provided from the first member to the second member.

[0048] In the above structure, the first component and the second component are both compacts of soft magnetic powder. In the above structure, the inner diameter of the lower hole is optimally selected according to the size of the self-tapping screw, so that cracks are less likely to occur in the first component and the second component.

[0049] <3> The following is one embodiment of the connected body according to the embodiment:

[0050] In a cross section cut through a plane including the axis of the self-tapping screw, the area occupied by the gap in the predetermined region is not less than 45% and not more than 65%,

[0051] The prescribed area is an area surrounded by the first straight line, the second straight line, the third straight line and the fourth straight line,

[0052] The first straight line connects the vertex of one tooth portion and the vertex of another tooth portion that are adjacent in the direction of the axis.

[0053] The second straight line includes the thread bottom of the self-tapping screw and extends along the thread bottom.

[0054] The third straight line extends from the vertex of the one tooth portion in a direction orthogonal to the axis.

[0055] The fourth straight line extends from the vertex of the other tooth portion in a direction perpendicular to the axis.

[0056] If the area occupied by the above-mentioned gap in the above-mentioned prescribed area is 45% or more and 65% or less, it can be said that the amount of bite of the self-tapping screw relative to the lower hole is appropriate. Therefore, the connection body in which the area occupied by the above-mentioned gap in the above-mentioned prescribed area is 45% or more and 65% or less can be said to be a connection body in which the first component and the second component are firmly fixed by the self-tapping screw. In addition, it can also be said that it is a connection body in which cracks, etc. are not likely to occur in the powder molded body.

[0057] <4> The following is one aspect of the connected body according to the embodiment:

[0058] The self-tapping screw is of B-0 type or B-1 type.

[0059] The B-0 type tapping screw is mainly used to fix resin materials. In addition, the B-1 type tapping screw is a tapping screw used to fix resin materials, and has a groove that serves as a cutting edge formed at its front end. These tapping screws are suitable for fixing powder compacts.

[0060] <5> The following is one embodiment of the connected body according to the embodiment:

[0061] The angle of the thread portion on the front end side of the self-tapping screw is smaller than the angle of the thread portion on the root side.

[0062] The angle of the thread, i.e. the angle of the thread tooth, is the angle formed by the two surfaces across the vertex of the thread when the self-tapping screw is cut in its axial direction. That is, a small angle of the thread can be said to mean that the thickness of the thread is thin and the thread is sharp. The self-tapping screw as described above is easy to screw into the lower hole.

[0063] <6> The following is one embodiment of the connected body according to the embodiment:

[0064] The self-tapping screw is non-magnetic.

[0065] When the connection body is used for the core of a rotating electrical machine, if the tapping screw is a non-magnetic material, the core loss caused by the tapping screw is reduced.

[0066] <7> The following is one aspect of the connected body according to the embodiment:

[0067] The non-magnetic body is resin, titanium alloy, brass, aluminum alloy, magnesium alloy or non-magnetic stainless steel.

[0068] The above-mentioned materials have the strength required for self-tapping screws.

[0069] <8> The following is one aspect of the connected body according to the embodiment:

[0070] The self-tapping screw is a magnet.

[0071] When the connection body is used for the core of a rotating electrical machine, if the self-tapping screw is a magnet, a reduction in the torque of the rotating electrical machine caused by the self-tapping screw can be suppressed.

[0072] <9> The following is one aspect of the connected body according to the embodiment:

[0073] The magnet is steel or magnetic stainless steel.

[0074] The above-mentioned materials have the strength required for self-tapping screws.

[0075] <10> The following is one aspect of the connected body according to the embodiment:

[0076] The tooth portion bites into the lower hole of the first component with more than five teeth.

[0077] In this specification, a thread portion of one thread refers to a thread portion corresponding to one pitch. When the thread portion of five or more threads is bitten into the lower hole, the first member and the second member are firmly fixed.

[0078] <11> The following is one aspect of the connected body according to the embodiment:

[0079] The distance between the bottom of the lower hole and the front end of the self-tapping screw is not less than 0.5 mm and not more than 5 mm.

[0080] If the distance is 0.5 mm or more, the front end of the self-tapping screw does not press the bottom of the lower hole. Therefore, damage to the first component caused by the front end of the self-tapping screw is suppressed. In addition, if the distance is 5 mm or less, the solid part of the first component is fully ensured. Therefore, the reduction of the magnetic properties of the first component is suppressed.

[0081] <12> The following is one aspect of the connected body according to the embodiment:

[0082] The inner peripheral surface of the lower hole has a tapered shape having an inclination of 1° to 10° with respect to the axis of the lower hole.

[0083] The lower hole having a predetermined tapered shape can be provided by molding. For example, a powder compact is produced by using a mold having a core for providing the lower hole. In this case, if the lower hole has a tapered shape, it is easy to pull the core out of the powder compact. When the lower hole is produced in the powder compact by molding, it is not necessary to perform mechanical processing on the powder compact. Therefore, cracks and the like are not likely to occur in the powder compact.

[0084] <13> The following is one aspect of the connected body according to the embodiment:

[0085] In a cross section cut through a plane including the axis of the tapping screw, the thickness of the first member and the thickness of the second member from the inner peripheral surface of the lower hole toward a direction perpendicular to the axis are 2 mm or more.

[0086] With the above structure, the wall thickness of the first component and the second component on the radially outer side of the lower hole is sufficiently ensured. Therefore, when the first component and the second component are fixed by the self-tapping screw, cracks are not likely to occur in the first component and the second component.

[0087] <14> The following is one aspect of the connected body according to the embodiment:

[0088] A filling material is arranged in the gap of the spiral shape.

[0089] The filling material is preferably filled in the lower hole before fixing by the self-tapping screw. By placing the filling material in the lower hole, cracks and the like are not easily generated in the powder compact when the self-tapping screw is installed relative to the lower hole. The reason for this is that the friction between the self-tapping screw and the lower hole is reduced. In addition, the gap between the inner peripheral surface of the lower hole and the outer peripheral surface of the self-tapping screw is filled with the filling material, thereby improving the strength of the powder compact.

[0090] <15> The following is one aspect of the connected body according to the embodiment:

[0091] The head of the self-tapping screw is a countersunk head type, a flat round head type or a round head type.

[0092] The self-tapping screw having the head of the above-mentioned shape is suitable for connecting the first component and the second component.

[0093] <16> The following is one aspect of the connected body according to the embodiment:

[0094] The relative density of the first component is above 90%,

[0095] The second component is a powder compact of soft magnetic powder, and the relative density of the second component is also 90% or more.

[0096] The relative density of the first member and the second member is obtained by image analysis or the like as described in the embodiment to be described later.

[0097] The magnetic properties of the powder compact with a relative density of 90% or more are excellent. In addition, the strength of the powder compact with a relative density of 90% or more is excellent. Therefore, when the first component and the second component are fixed by a self-tapping screw, it is not easy for the powder compact to crack or chip.

[0098] <17> The following is one aspect of the connected body according to the embodiment:

[0099] The first component is a tooth portion used in the core of a rotating electrical machine,

[0100] The second member is a yoke used in the core.

[0101] With the above structure, it is easy to fix the tooth portion to the yoke portion.

[0102] <18> The following is one aspect of the connected body according to the embodiment:

[0103] The first component is a tooth portion used in the core of a rotating electrical machine,

[0104] The second member is a flange portion provided at an end portion of the tooth portion.

[0105] With the above structure, the flange portion can be easily fixed to the teeth portion.

[0106] <19> The following is one aspect of the connected body according to the embodiment:

[0107] The first component is an iron core having a tooth portion and a yoke portion and used in a rotating electrical machine,

[0108] The second member is a case that houses the core.

[0109] With the above structure, the core can be easily fixed to the case.

[0110] <20> The rotating electrical machine according to the embodiment is an axial gap type rotating electrical machine in which a rotor and a stator are arranged in the axial direction of a rotating shaft of the rotor.

[0111] A connected body comprising any one of the above <17> to <19>.

[0112] The above-mentioned rotating electrical machine has excellent productivity because a component constituting a part of the rotating electrical machine is the coupled body of the present invention which has excellent productivity.

[0113] [Details of the embodiments of the present invention]

[0114] Based on the accompanying drawings, a specific example of a coupling body and a rotating electric machine using the coupling body according to an embodiment of the present invention is described. The same reference numerals in the figures represent the same or equivalent parts. In addition, the present invention is not limited to these examples, but is shown by the claims, including all changes within the meaning and scope equivalent to the claims.

[0115] <Implementation method 1>

[0116] In the first embodiment, as the connection body 1 of the present invention, Figure 1 The iron core 30 included in the rotating electrical machine 100 shown will be described.

[0117] 《Rotating Electric Machines》

[0118] The rotating electrical machine 100 may be a generator or a motor such as a motor. The rotating electrical machine 100 includes a rotor 2 and a stator 3 disposed in a housing 9. The rotating electrical machine 100 of this example is an axial gap type rotating electrical machine 100 in which the rotor 2 and the stator 3 are arranged in the direction of the rotation axis of the rotor 2.

[0119] Rotor

[0120] The rotor 2 has a plurality of flat magnets 22 and a ring-shaped retaining plate 21 that supports the magnets 22. The retaining plate 21 is fixed to the shaft 20 and rotates together with the shaft 20. The magnets 22 are embedded in the retaining plate 21. The magnets 22 are arranged at intervals in the circumferential direction of the shaft 20. In addition, the magnets 22 are magnetized in the direction of the rotation axis of the rotor 2, that is, in the axial direction of the shaft 20. The magnetization directions of the magnets 22 adjacent to each other in the circumferential direction of the shaft 20 are opposite to each other.

[0121] ·stator

[0122] The stator 3 has an iron core 30 and a coil 31 arranged on the tooth portion 4 of the iron core 30. The rotating electric machine 100 of this example has two stators 3. The end face of the tooth portion 4 of one stator 3 is opposite to the end face of the tooth portion 4 of the other stator 3. The two stators 3, 3 are arranged opposite to the rotor 2 in the axial direction of the shaft 20 and fixed to the housing 9. Therefore, the rotor 2 is sandwiched by the two stators 3, 3. A bearing 33 is arranged between the stator 3 and the shaft 20, and the stator 3 does not rotate. The iron core 30 of the stator 3 of this example is the coupling body 1 of the present invention.

[0123] Iron Core

[0124] like Figures 1 to 3 As shown, the connection body 1 of this example, that is, the iron core 30, has a tooth portion 4 and a yoke portion 5. The iron core 30 of this example has six teeth 4 ( Figure 2). The number of teeth 4 is not particularly limited. When the rotating electrical machine 100 is used in a three-phase AC, the number of teeth 4 is set to 3n. n is a natural number. In this example, the teeth 4 are the first component 11 ( Figure 4 ), the yoke 5 is the second component 12 ( Figure 4 ). The tooth portion 4 and the yoke portion 5 are manufactured separately.

[0125] ·Gear

[0126] The tooth portion 4 of this example is a component in the shape of a roughly trapezoidal column. The shape of the tooth portion 4 is not particularly limited. For example, the tooth portion 4 may also be in the shape of a roughly triangular prism. In addition, the shape of the tooth portion 4 may also be in the shape of a cylinder, a quadrangular prism, etc. A flange portion may be provided at the end of the tooth portion 4 on the opposite side of the yoke portion 5. The flange portion is a component that extends in a direction orthogonal to the protruding direction of the tooth portion 4 and is provided integrally with the tooth portion 4.

[0127] The tooth portion 4 is a powder compact formed by compression molding of soft magnetic powder. Soft magnetic powder is an aggregate of soft magnetic particles. As soft magnetic powder, for example, at least one powder selected from pure iron with a purity of 99 mass % or more and Fe-Si-Al alloys, Fe-Si alloys, Fe-Al alloys, Fe-Ni alloys and other iron-based alloys is cited. Fe is iron, Si is silicon, Al is aluminum, and Ni is nickel. As Fe-Si-Al alloys, sendust is cited, as Fe-Si alloys, silicon steel is cited, and as Fe-Ni alloys, permalloy is cited. The soft magnetic particles preferably have an insulating coating layer on their surface. An insulating coating layer is formed on the surface of the soft magnetic particles, thereby ensuring electrical insulation between the soft magnetic particles. Therefore, the iron loss of the tooth portion 4 caused by eddy current loss can be reduced. As insulating coating layers, for example, phosphate coating layers, silica coating layers, etc. are cited.

[0128] The average particle size of the soft magnetic particles can be set to be greater than 10 μm and less than 300 μm. If the average particle size of the soft magnetic particles is greater than 10 μm, the increase in the coercive force and hysteresis loss of the powder compact can be suppressed. If the average particle size of the soft magnetic particles is less than 300 μm, the eddy current loss of the powder compact occurring in the high frequency band is reduced. The more preferred average particle size of the soft magnetic particles is greater than 40 μm and less than 260 μm. Here, the average particle size refers to the particle size of the particles whose sum of mass from particles with a small particle size in the histogram of the particle size reaches 50% of the total mass, that is, the 50% particle size.

[0129] The relative density of the powder compact is preferably 90% or more. The magnetic properties of the powder compact are improved by increasing the density of the powder compact. The relative density of the powder compact is preferably 93% or more, more preferably 94% or more, and even more preferably 95% or more. The above relative density is a value obtained by dividing the actual density of the powder compact by the true density. The actual density is obtained by measuring the volume of the powder compact by the Archimedean method and dividing the mass of the powder compact by the measured volume. The true density is obtained by using a measuring device such as a hydrometer.

[0130] ·Yoke

[0131] The yoke 5 is a ring-shaped component. The yoke 5 of this example is composed of a single component. The yoke 5 can also be composed of a plurality of split pieces. For example, the ring-shaped yoke 5 can be made by connecting fan-shaped split pieces.

[0132] The yoke 5 is composed of a powder compact similar to the tooth 4. The composition of the powder compact constituting the yoke 5 may be the same as or different from the composition of the powder compact constituting the tooth 4. In addition, the relative density of the yoke 5 may be the same as or different from the relative density of the tooth 4. However, the relative density of the yoke 5 is preferably 90% or more.

[0133] ·Connection structure of the tooth and yoke

[0134] The teeth 4 and yoke 5 constituting the core 30 are fixed by self-tapping screws 6. The self-tapping screws 6 are installed from the surface of the yoke 5 opposite to the teeth 4 toward the teeth 4. The core 30, the teeth 4 and the yoke 5 are the connection body 1, the first component 11 and the second component 12 respectively.

[0135] like Figure 4 , 5 As shown, in this example, the connecting body 1 is provided with a lower hole 7 that penetrates the second component 12 and reaches the first component 11. That is, the lower hole 7 is provided from the first component 11 to the second component 12. The lower hole 7 is composed of a through hole provided in the second component 12 and a blind hole provided in the first component 11. The through hole and the blind hole are coaxial. In addition, the inner diameter of the through hole is the same as or larger than the inner diameter of the blind hole. The lower hole 7 is pre-set in the first component 11 and the second component 12. The thread portion 65 ( Figure 5 ) bites into the inner circumferential surface of the lower hole 7.

[0136] Preferably, the teeth 65 with five or more teeth are bitten into the lower hole 7. Specifically, preferably, the teeth 65 with five or more teeth are bitten into the portion of the lower hole 7 corresponding to the first component 11. By biting the teeth 65 with five or more teeth into the lower hole 7, the first component 11 and the second component 12 are firmly fixed.

[0137] like Figure 5 As shown, the inner diameter h of the lower hole 7 is not less than 83% and not more than 95% of the diameter d of the thread of the self-tapping screw 6, and is larger than the diameter d1 of the thread bottom of the self-tapping screw 6. The thread diameter d is the diameter of the portion corresponding to the apex 65t of the thread portion 65 of the self-tapping screw 6. The thread bottom diameter d1 is the diameter of the portion corresponding to the bottom of the thread bottom portion 66, i.e., the groove bottom. If the inner diameter h of the lower hole 7 is not less than 83% of the diameter d of the thread of the self-tapping screw 6, the thread portion 65 of the self-tapping screw 6 suppresses excessive stress from acting on the lower hole 7. If the inner diameter h of the lower hole 7 is not more than 95% of the diameter d of the thread of the self-tapping screw 6, the thread portion 65 is fully bitten into the lower hole 7. In addition, if the inner diameter h of the lower hole 7 is larger than the diameter d1 of the thread bottom of the self-tapping screw 6, the lower hole 7 will not be pressed and expanded radially outward by the shaft portion 60 of the self-tapping screw 6. Therefore, problems such as cracks are less likely to occur in the first member 11 and the second member 12 formed of the powder compact.

[0138] The inner diameter h of the lower hole 7 is preferably 84% to 94% of the thread diameter d of the tapping screw 6. The inner diameter h of the lower hole 7 is more preferably 85% to 93% of the thread diameter d of the tapping screw 6.

[0139] The thread bottom 66 of the self-tapping screw 6 does not contact the lower hole 7 (also refer to Figure 6 Therefore, in the connection body 1 of this example, a spiral gap 8 is formed which is surrounded by the outer peripheral surface of the self-tapping screw 6 and the inner peripheral surface of the lower hole 7. Specifically, the outer peripheral surface of the self-tapping screw 6 is the outer peripheral surface of the thread portion 65 and the outer peripheral surface of the thread bottom portion 66.

[0140] exist Figure 5 In the cross section shown in FIG. 1 , which is cut through a plane including the axis of the self-tapping screw 6, the area occupied by the gap 8 in the specified area 80 is preferably not less than 45% and not more than 65%. The specified area 80 is an area of ​​the cross section surrounded by the first straight line L1, the second straight line L2, the third straight line L3 and the fourth straight line L4. The first straight line L1 is a straight line connecting the vertex 65t of one tooth portion 65 and the vertex 65t of another tooth portion 65 adjacent in the direction of the axis. The second straight line L2 is a straight line extending along the bottom of the groove, which includes the bottom of the tooth bottom 66 of the self-tapping screw 6. The third straight line L3 is a straight line extending from the vertex 65t of one tooth portion 65 to a direction orthogonal to the above-mentioned axis. The fourth straight line L4 is a straight line extending from the vertex 65t of the other tooth portion 65 to a direction orthogonal to the above-mentioned axis.

[0141] If the area occupied by the gap 8 in the predetermined region 80 is 45% to 65%, it can be said that the amount of bite of the self-tapping screw 6 into the lower hole 7 is appropriate. Therefore, the connected body 1 in which the area occupied by the gap 8 in the predetermined region 80 is 45% to 65% can be said to be a connected body 1 in which the first component 11 and the second component 12 are firmly fixed by the self-tapping screw 6. In addition, it can also be said that it is a connected body 1 in which cracks and the like are not likely to occur in the first component 11 and the second component 12 composed of the powder compact. A more preferred area ratio is 47% to 63%. A further preferred area ratio is 49% to 61%.

[0142] like Figure 4 As shown, a gap is preferably formed between the bottom 7b of the lower hole 7 and the front end 6p of the self-tapping screw 6. The distance between the bottom 7b of the lower hole 7 and the front end 6p of the self-tapping screw 6 is preferably not less than 0.5mm and not more than 5mm. If the above distance is not less than 0.5mm, the front end 6p of the self-tapping screw 6 will not press the bottom 7b of the lower hole 7. Therefore, damage to the first component 11 caused by the front end of the self-tapping screw 6 is suppressed. In addition, if the above distance is not more than 5mm, the solid part of the first component 11 is fully ensured. Therefore, the reduction of the magnetic properties of the first component 11 is suppressed. The distance is more preferably not less than 1mm and not more than 4mm.

[0143] The self-tapping screw 6 of this example is a B-0 type self-tapping screw 6. The B-0 type self-tapping screw 6 is mainly used to fix resin materials. In addition, in order to easily screw the self-tapping screw 6 into the lower hole 7, the angle of the thread portion on the front end side of the self-tapping screw 6 can be made smaller than the angle of the thread portion on the root side.

[0144] The self-tapping screw 6 has: a shaft portion 60 having a thread portion 65; and a head portion 61, which is provided at one end of the shaft portion 60. The head portion 61 of this example is a pan head type, but is not particularly limited. For example, the head portion 61 may also be a countersunk head type, a truss head type, or a binding head type. In addition, the self-tapping screw 6 of this example also has a washer portion 62 integrated with the head portion 61. The washer portion 62 may also be absent.

[0145] The pitch P of the self-tapping screw 6 is preferably not less than 25% and not more than 43% of the nominal diameter. The pitch P is the interval between two axially adjacent teeth 65. If the pitch P is not less than 25% of the nominal diameter, it is not easy to apply excessive stress to the lower hole 7. In addition, if the above pitch P is not more than 43% of the nominal diameter, the teeth 65 of the self-tapping screw 6 are firmly bitten into the lower hole 7. Therefore, the fixing of the first component 11 and the second component 12 by the self-tapping screw 6 becomes firm. A more preferred pitch P is not less than 28% and not more than 40% of the nominal diameter.

[0146] The self-tapping screw 6 can be a non-magnetic body or a magnetic body. As a non-magnetic body, for example, resin, titanium alloy, brass, aluminum alloy, magnesium alloy or non-magnetic stainless steel are cited. As resins, nylon (registered trademark), polycarbonate (polycarbonate), PEEK (polyetheretherketone) and the like are cited. These non-magnetic bodies have excellent strength and are therefore suitable as materials for the self-tapping screw 6. If the self-tapping screw 6 is a non-magnetic body, the generation of eddy current of the self-tapping screw 6 is suppressed. Therefore, the energy loss of the core 30, that is, the core loss, is reduced. In particular, stainless steel has excellent corrosion resistance, so the loosening of the self-tapping screw 6 associated with corrosion can be suppressed.

[0147] As the magnet constituting the tapping screw 6, for example, steel or ferromagnetic stainless steel is cited. These magnets are excellent in strength and are therefore suitable as the material of the tapping screw 6. If the tapping screw 6 is a magnet, the tapping screw 6 functions as a part of the iron core 30. Therefore, the rotation of the electric machine 100 ( Figure 1 ) The torque is reduced. In particular, stainless steel has excellent corrosion resistance, so the loosening of the tapping screw 6 associated with corrosion can be suppressed.

[0148] The inner peripheral surface of the lower hole 7 provided in the first component 11 and the second component 12 preferably has a tapered shape, and the tapered shape has an inclination of 1° or more and 10° or less relative to its axis. In the case where the lower hole 7 has a tapered shape, the inner diameter h of the lower hole 7 needs to meet the provisions of the present invention at the position where the inner diameter h of the lower hole 7 is the smallest among the parts of the lower hole 7 that contact the tooth portion 65 of the self-tapping screw 6. The lower hole 7 having a prescribed tapered shape can be provided by molding. For example, the first component 11 and the second component 12 are made using a mold having a core for providing the lower hole 7. In this case, if the lower hole 7 has a tapered shape, it is easy to pull the core out from the first component 11 and the second component 12. In the case where the lower hole 7 is made in the first component 11 and the second component 12 by molding, it is not necessary to perform mechanical processing on the first component 11 and the second component 12. Therefore, it is not easy for cracks to occur in the first component 11 and the second component 12.

[0149] exist Figure 4The thickness of the first component 11 and the thickness of the second component 12 in the direction perpendicular to the axis from the inner circumference of the lower hole 7 are preferably 2 mm or more. Figure 4 The above structure ensures that the wall thickness of the first component 11 and the second component 12 on the radially outer side of the lower hole 7 is sufficient. Therefore, when the first component 11 and the second component 12 are fixed by the self-tapping screw 6, cracks are not likely to occur in the first component 11 and the second component 12.

[0150] like Figure 5 As shown, a filling material 8r may be arranged in the gap 8. The filling material 8r is preferably filled in the lower hole 7 before fixing by the self-tapping screw 6. By arranging the filling material 8r in the lower hole 7, when the self-tapping screw 6 is installed relative to the lower hole 7, cracks are not easily generated in the first component 11 and the second component 12. This is because the friction between the self-tapping screw 6 and the lower hole 7 is reduced. In addition, by filling the gap 8 with the filling material 8r, the strength of the first component 11 and the second component 12 is improved. As the filling material 8r, for example, an epoxy resin adhesive is cited.

[0151] <<Effects of the present embodiment>>

[0152] In the above embodiment, the iron core 30 is the connection body 1, the tooth portion 4 is the first component 11, and the yoke portion 5 is the second component 12. The iron core 30 of the above embodiment can be manufactured by simply fixing the tooth portion 4 and the yoke portion 5 with the self-tapping screws 6. Compared with fixing by press-fitting and fixing by an adhesive, fixing by the self-tapping screws 6 is easier. Therefore, the iron core 30 of the first embodiment is excellent in productivity.

[0153] The stator 3 ( Figure 1 ) has excellent productivity. This is because the productivity of the iron core 30 included in the stator 3 is high.

[0154] The rotary electric machine 100 including the stator 3 of the above-described embodiment has excellent productivity. This is because the productivity of the stator 3 included in the rotary electric machine 100 is high.

[0155] <Implementation method 2>

[0156] In implementation mode 2, based on Figure 7 A rotary electric machine 100 in which the core 30 is fixed to the case 9 by the self-tapping screws 6 will be described.

[0157] The iron core 30 of the second embodiment is a powder compact in which the tooth portion 4 and the yoke portion 5 are integrated. That is, in this example, the iron core 30 is the first component 11. The iron core 30 is fixed to the housing 9 by the self-tapping screws 6. That is, in this example, the housing 9 is the second component 12. As the material of the housing 9, non-magnetic materials such as aluminum alloy are cited.

[0158] If the inner diameter of the lower hole 7 is the same as that of the first embodiment, the iron core 30 of the powder compact can be fixed to the housing 9 without cracks or breakages. The structure of this example makes it easy to manufacture the rotating electric machine 100. This is because the operator can fix the iron core 30 to the housing 9 by only screwing the iron core 30 to the housing 9.

[0159] <Implementation method 3>

[0160] In implementation mode 3, based on Figure 8 A rotary electric machine 100 in which a flange portion 45 is provided at an end portion of a tooth portion 4 will be described.

[0161] In this example, a flange portion 45 is provided at the end of the tooth portion 4 on the opposite side from the yoke portion 5, and extends in a direction perpendicular to the protruding direction of the tooth portion 4. The flange portion 45 prevents the coil 31 arranged on the tooth portion 4 from being separated from the tooth portion 4. In addition, the flange portion 45 improves the performance of the axial gap type rotating electric machine 100.

[0162] In this example, the integrated body of the teeth 4 and the yoke 5 is a first member 11 of a compact. On the other hand, the flange 45 is a second member 12 separate from the teeth 4. The flange 45 may be a compact or a laminated steel plate.

[0163] If the inner diameter of the lower hole 7 is the same as that of the first embodiment, even if the flange portion 45 is a powder compact, cracks and ruptures will not occur in the flange portion 45. With the structure of this example, the flange portion 45 is easily formed. The reason is that the operator can fix the flange portion 45 to the tooth portion 4 by only screwing the flange portion 45 at the end of the tooth portion 4. Therefore, the productivity of the rotating electric machine 100 is improved. In addition, according to the structure of this example, compared with the existing structure using a fixing agent, the gap between the tooth portion 4 and the flange portion 45 can be reduced, and the reduction in motor performance can be suppressed.

[0164] 《Variant 3-1》

[0165] As a modification of the third embodiment, a method of applying the structure of the first embodiment to the structure of the third embodiment is given. That is, a method of manufacturing the tooth portion 4, the yoke portion 5, and the flange portion 45 separately from each other, fastening the tooth portion 4 and the yoke portion 5 by screws, and fastening the tooth portion 4 and the flange portion 45 by screws is given. When the tooth portion 4 and the yoke portion 5 are connected, the tooth portion 4 is the first component 11, and the yoke portion 5 is the second component 12. In addition, when the tooth portion 4 and the flange portion 45 are connected, the tooth portion 4 is the first component 11, and the flange portion 45 is the second component 12.

[0166] 《Variant 3-2》

[0167] As a modification of the third embodiment, the structure of the second embodiment is applied to the structure of the third embodiment. That is, the teeth 4 and the flange 45 of the core 30 are screwed together, and the core 30 and the housing 9 are screwed together. When the teeth 4 and the flange 45 are connected, the core 30 is the first component 11, and the flange 45 is the second component 12. In addition, when the core 30 and the housing 9 are connected, the core 30 is the first component 11, and the housing 9 is the second component 12.

[0168] <Implementation method 4>

[0169] The self-tapping screw 6 used in Embodiments 1 to 3 may be Fig. 9 The B-1 type tapping screw 6 is shown. The B-1 type tapping screw 6 has a groove 69 at its front end. In the B-1 type tapping screw 6, the edge of the groove 69 functions as a cutting edge.

[0170] <Test example>

[0171] In the test example, the iron cores of samples No. 1 to No. 5 shown below were produced. The presence or absence of cracks when producing each iron core was investigated. In addition, the core loss of the rotating electric machine using the iron cores of samples No. 1 to No. 5 was investigated.

[0172] 《Sample Information》

[0173] Sample No.1

[0174] The core of sample No. 1 is a core obtained by fixing the teeth and yoke parts which are separately manufactured by adhesive. The relative density of the teeth and yoke parts is 95%.

[0175] Sample No.2

[0176] The core of sample No. 2 is an iron core obtained by fixing the tooth part and the yoke part by self-tapping screws. The self-tapping screws are engineering plastics (trade name) manufactured by Nitto Seiko Co., Ltd. The size and relative density of the tooth part and the yoke part are the same as those in embodiment 1. The self-tapping screw is of B-0 type, with a tooth diameter of 3 mm and a tooth bottom diameter of 2.3 mm. On the other hand, the inner diameter of the lower hole is 2.4 mm. The inner diameter of the lower hole 7 is the diameter before the self-tapping screw is installed. The inner diameter of the lower hole / the diameter of the self-tapping screw's tooth is 0.8. That is, the inner diameter of the lower hole is 80% of the diameter of the self-tapping screw's tooth. The self-tapping screw is installed by an electric screwdriver. The rotation speed of the self-tapping screw is 300 rpm, and the force for rotating the self-tapping screw is 49 N·m.

[0177] Sample No.3

[0178] The core of sample No. 3 is the same as the core of sample No. 2 except that the inner diameter of the lower hole is 2.5 mm. The inner diameter of the lower hole of sample No. 3 is 83% of the diameter of the thread of the self-tapping screw.

[0179] Sample No.4

[0180] The core of sample No. 4 is the same as the core of sample No. 2 except that the inner diameter of the lower hole is 2.8 mm. The inner diameter of the lower hole of sample No. 4 is 93% of the diameter of the thread of the self-tapping screw 6 .

[0181] Sample No.5

[0182] The core of sample No. 5 is the same as the core of sample No. 2 except that the inner diameter of the lower hole is 2.9 mm. The inner diameter of the lower hole of sample No. 5 is 97% of the diameter of the thread of the self-tapping screw 6 .

[0183] Sample No.6

[0184] The core of sample No. 6 is the same as the core of sample No. 2 except that the thread diameter of the self-tapping screw 6 is 4 mm, the thread bottom diameter is 3.0 mm, and the inner diameter of the lower hole is 3.6 mm. The inner diameter of the lower hole of sample No. 5 is 90% of the thread diameter of the self-tapping screw.

[0185] 《Test Results》

[0186] The presence or absence of cracks and core loss (W / kg) of each sample were investigated. The presence or absence of cracks was determined visually. In addition, the core loss was measured at 1.0T / 1kHz. The results of each sample are shown in Table 1 below. In Table 1, "lower hole inner diameter / diameter of self-tapping screw tooth" is expressed as "lower hole diameter / tooth diameter". "Presence or absence of cracks" in Table 1 indicates whether capillary cracks have occurred in either the yoke or the tooth.

[0187] For each sample, the starting torque (N·m), breaking torque (N·m), appropriate tightening torque range (N·m), relaxation rate (%) and screw pull-out force (kN) were measured. The starting torque is the torque at which the thread starts to form in the lower hole. The breaking torque is the torque at which at least one of the external thread of the self-tapping screw or the internal thread formed in the lower hole breaks. The starting torque and breaking torque are measured by a commercially available torque tester. The larger the size of the self-tapping screw, the greater the starting torque and breaking torque.

[0188] The appropriate tightening torque range is a torque width from 1.5× (starting torque) to 0.65× (breaking torque). The wider this range is, the easier it is to tighten the tapping screw and fix the tapping screw to the object.

[0189] The relaxation rate is expressed by (T / 1)×100 when the torque required to screw out the tapping screw by reversely rotating the tapping screw after the tapping screw is tightened with a force of 1 N·m is T. If the relaxation rate is 50% or more, it can be determined that the tapping screw has been bitten into the lower hole.

[0190] The screw pull-out force was investigated using a test sample prepared separately from the iron core. The test sample is a powder compact made of the same material and with the same relative density as the iron core. In addition, a through hole is formed in the test sample as a lower hole. After the self-tapping screw is tightened in the lower hole of the test sample, the maximum load required to press the self-tapping screw out of the lower hole by pressing the front end of the shaft of the self-tapping screw, that is, the end on the opposite side of the head, is the screw pull-out force. The greater the screw pull-out force, the more difficult it is to pull the self-tapping screw out of the lower hole.

[0191] [Table 1]

[0192]

[0193] As shown in Table 1, the core loss of sample No. 1 was 25 W / kg. In addition, in sample No. 1 in which the teeth and the yoke were connected by an adhesive, cracks did not occur originally.

[0194] The core of sample No. 2, in which the inner diameter of the lower hole is less than 83% of the diameter of the thread of the self-tapping screw, cracks occurred in the tooth and yoke. On the other hand, the cores of samples No. 3 to No. 6, in which the inner diameter of the lower hole is more than 83% of the diameter of the thread of the self-tapping screw, did not crack in the tooth and yoke. Therefore, it can be seen that when the tooth and yoke composed of the pressed powder molded body are fixed by the self-tapping screw, the inner diameter of the lower hole needs to be set to more than 83% of the diameter of the thread of the self-tapping screw.

[0195] The core loss of sample No. 2 is greater than the core losses of samples No. 3 and No. 6. It is presumed that the reason why the core loss of sample No. 2 is large is that cracks occurred in the core.

[0196] In the core of sample No.5, where the inner diameter of the lower hole exceeds 95% of the diameter of the thread of the self-tapping screw, the appropriate tightening torque range of the self-tapping screw is narrow, making it difficult to tighten the self-tapping screw. In addition, in the core of sample No.5, the screw pull-out force is small, and the self-tapping screw is easily pulled out from the lower hole. On the other hand, in the cores of samples No.3, 4, and 6, where the inner diameter of the lower hole is less than 95% of the diameter of the thread of the self-tapping screw, the appropriate tightening torque range of the self-tapping screw is large, making it easy to tighten the self-tapping screw. In addition, in the cores of samples No.3, 4, and 6, the screw pull-out force is large, and the self-tapping screw is difficult to pull out from the lower hole.

[0197] Description of the label

[0198] 100 Rotating Motor

[0199] 1 Connected Body

[0200] 11 first part, 12 second part

[0201] 2 Rotors

[0202] 20 shaft, 21 holding plate, 22 magnet

[0203] 3. Stator

[0204] 30 iron core, 31 coil, 33 bearing

[0205] 4 teeth

[0206] 5 yoke parts

[0207] 6 Self-tapping screws

[0208] 60 shaft, 61 head, 62 washer, 65 tooth, 65t apex

[0209] 66 teeth bottom, 69 grooves

[0210] 7 lower holes

[0211] 8 Clearance

[0212] 8r Filling material

[0213] 80 Specified Areas

[0214] L1 is the first straight line, L2 is the second straight line, L3 is the third straight line, L4 is the fourth straight line

[0215] 9 Shell

Claims

1. A connected body, comprising: A first component, which is composed of a powder compact of soft magnetic powder; a second component separate from the first component; and A self-tapping screw penetrates the second member and reaches the first member to connect the first member and the second member. At least the first component of the first component and the second component has a lower hole for the thread of the self-tapping screw to bite into, The inner diameter of the lower hole is not less than 83% and not more than 95% of the diameter of the thread of the self-tapping screw, and is larger than the diameter of the thread bottom of the self-tapping screw. A spiral gap is formed between the outer peripheral surface of the self-tapping screw and the inner peripheral surface of the lower hole. In a cross section cut through a plane including the axis of the self-tapping screw, the area occupied by the gap in the predetermined region is not less than 45% and not more than 65%, The prescribed area is an area surrounded by the first straight line, the second straight line, the third straight line and the fourth straight line, The first straight line connects the vertex of one tooth portion and the vertex of another tooth portion that are adjacent in the direction of the axis. The second straight line includes the thread bottom of the self-tapping screw and extends along the thread bottom. The third straight line extends from the vertex of the one tooth portion in a direction orthogonal to the axis. The fourth straight line extends from the vertex of the other tooth portion in a direction perpendicular to the axis.

2. The connection body according to claim 1, wherein: The second component is composed of a powder compact of soft magnetic powder. The lower hole is provided from the first member to the second member.

3. The connection body according to claim 1 or 2, wherein: The self-tapping screw is of the B-0 type or the B-1 type. The B-0 type self-tapping screw is used to fix resin materials. The B-1 type self-tapping screw is a self-tapping screw used to fix resin materials and has a groove serving as a cutting edge formed at its front end.

4. The connection body according to claim 1 or 2, wherein: The angle of the thread portion on the front end side of the self-tapping screw is smaller than the angle of the thread portion on the root side.

5. The connection body according to claim 1 or 2, wherein: The self-tapping screw is non-magnetic.

6. The connection body according to claim 5, wherein: The non-magnetic body is resin, titanium alloy, brass, aluminum alloy, magnesium alloy or non-magnetic stainless steel.

7. The connection body according to claim 1 or 2, wherein: The self-tapping screw is a magnet.

8. The connection body according to claim 7, wherein: The magnet is steel.

9. The connection body according to claim 1 or 2, wherein: The tooth portion bites into the lower hole of the first component with more than five teeth.

10. The connection body according to claim 1 or 2, wherein: The distance between the bottom of the lower hole and the front end of the self-tapping screw is not less than 0.5 mm and not more than 5 mm.

11. The connection body according to claim 1 or 2, wherein: The inner peripheral surface of the lower hole has a tapered shape having an inclination of 1° to 10° with respect to the axis of the lower hole.

12. The connection body according to claim 1 or 2, wherein: In a cross section cut through a plane including the axis of the tapping screw, the thickness of the first member and the thickness of the second member from the inner peripheral surface of the lower hole toward a direction perpendicular to the axis are 2 mm or more.

13. The connection body according to claim 1 or 2, wherein: A filling material is arranged in the gap of the spiral shape.

14. The connection body according to claim 1 or 2, wherein: The head of the self-tapping screw is a countersunk head type, a flat round head type or a round head type.

15. The connection body according to claim 1 or 2, wherein: The relative density of the first component is above 90%, The second component is a powder compact of soft magnetic powder, and the relative density of the second component is also 90% or more.

16. The connection body according to claim 1 or 2, wherein: The first component is a tooth portion used in the core of a rotating electrical machine, The second member is a yoke used in the core.

17. The connection body according to claim 1 or 2, wherein: The first component is a tooth portion used in the core of a rotating electrical machine, The second member is a flange portion provided at an end portion of the tooth portion.

18. The connection body according to claim 1 or 2, wherein: The first component is an iron core having a tooth portion and a yoke portion and used in a rotating electrical machine, The second member is a case that houses the core.

19. A rotating electrical machine, which is an axial gap type rotating electrical machine in which a rotor and a stator are arranged in the axial direction of a rotating shaft of the rotor, This rotating electrical machine includes the connected body according to any one of claims 16 to 18.

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