stata

Abstract

To provide an outer rotor type motor stator that can securely fix the segmented core and is easy to assemble. [Solution] The stator of the present invention is a stator for an outer rotor type motor, equipped with a stator core located on the outer diameter side of the motor housing. Furthermore, the stator core is formed by connecting fan-shaped electromagnetic steel sheets in the circumferential direction to create annular electromagnetic steel sheets, arranging these annular electromagnetic steel sheets with their connecting portions offset in the circumferential direction between adjacent annular electromagnetic steel sheets, and bonding these annular electromagnetic steel sheets together to form a laminated structure in the axial direction. A key protruding from the inner diameter side formed on the stator core is inserted into an axially extending keyway formed on the outer diameter side of the motor housing. Since the stator core is fixed to the motor housing with a fastener that penetrates its key axially, it is possible to provide an outer rotor type motor stator that can securely fix the divided core and is easy to assemble.

Description

Technical Field

[0006] , , , , ,

[0001] The present invention relates to a stator, and more particularly to a stator for an outer-rotor type motor.

Background Art

[0002] An outer-rotor type motor in which a coil is arranged inside and a magnet is arranged outside and the outside is rotated is known. Since the stator core of this motor cannot be fixed from the outer diameter side, it is necessary to firmly fix it to the motor housing on the inner diameter side to prevent displacement due to the magnetic attractive force received from the rotor.

[0003] However, when using a low-loss amorphous electromagnetic steel sheet for the stator core, since the sheet width of the electromagnetic steel sheet is limited, it is necessary to adopt a split core structure in which a plurality of cores are connected to form an annular shape, and it is difficult to ensure a design strength that can withstand the magnetic attractive force applied to the core material and the rotational torque reaction force of the rotor.

[0004] Although not related to the stator, Patent Document 1 describes a rotor in which a core formed of a split core is arranged on the outer periphery of a shaft. This rotor has a reverse taper-shaped protrusion whose width expands as it approaches the core provided on the outer periphery of the shaft, and a reverse taper-shaped protrusion whose width expands as it approaches the shaft provided on the inner periphery of the above core. It is described that by fitting these protrusions, it is possible to prevent the above core from expanding in diameter due to the centrifugal force caused by rotation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0007] In addition, during assembly, the numerous protrusions, formed with high machining precision and with virtually no gaps, must be simultaneously fitted onto the shaft, making assembly difficult and reducing productivity.

[0008] This invention has been made in view of the problems of the prior art, and its objective is to provide a stator that can securely fix divided cores and is easy to assemble. [Means for solving the problem]

[0009] As a result of diligent research to achieve the above objective, the inventors of the present invention have found that the above objective can be achieved by laminating multiple annular electromagnetic steel plates, each consisting of fan-shaped electromagnetic steel plates connected together, and by fixing the annular electromagnetic steel plates to a motor housing with fasteners that penetrate the annular electromagnetic steel plates in the axial direction, and have thus completed the present invention.

[0010] In other words, the stator of the present invention is a stator for an outer rotor type motor, equipped with a stator core positioned on the outer diameter side of the motor housing. Furthermore, the stator core is formed by connecting fan-shaped electromagnetic steel sheets in the circumferential direction to create annular electromagnetic steel sheets, arranging these annular electromagnetic steel sheets with their connecting portions offset in the circumferential direction between adjacent annular electromagnetic steel sheets, and bonding these annular electromagnetic steel sheets together to form a laminated structure in the axial direction. A key protruding from the inner diameter side formed on the stator core is inserted into an axially extending keyway formed on the outer diameter side of the motor housing. The stator core is characterized in that it is fixed to the motor housing by a fastener through which its key passes in the axial direction. [Effects of the Invention]

[0011] According to the present invention, since a plurality of annular electromagnetic steel plates formed by connecting fan-shaped electromagnetic steel plates are fixed to the motor housing by fasteners that penetrate the annular electromagnetic steel plates in the axial direction, the stator core can be securely fixed and a stator that is easy to assemble can be provided. [Brief explanation of the drawing]

[0012] [Figure 1] This is an exploded perspective view of the stator of the present invention. [Figure 2] This diagram shows a stacked arrangement of fan-shaped electrical steel sheets. [Figure 3] This diagram shows the state in which the protrusions of fan-shaped electromagnetic steel sheets are fitted together to connect adjacent fan-shaped electromagnetic steel sheets, and the shape of the protrusions. [Figure 4] This diagram shows the teeth and keys of a fan-shaped electrical steel sheet. [Modes for carrying out the invention]

[0013] The stator of the present invention will be described in detail. The stator of the present invention is a stator for an outer rotor type motor in which coils are arranged on the inside and magnets are arranged on the outside to rotate an outer rotor. As shown in Figure 1, a stator core 2 made of electromagnetic steel sheet is arranged on the outer diameter side of a cylindrical motor housing 1, and the stator core 2 has teeth 22 on its outer diameter side around which coils (not shown) are wound.

[0014] As described above, the stator core of an outer rotor type motor is pulled in the radial direction by the magnetic attraction force of the rotor's magnets, and also receives a circumferential torque reaction force due to the rotation of the rotor.

[0015] As shown in FIG. 1, the stator core of the present invention has a key 21 protruding toward the motor housing side on its inner diameter side, and the key 21 is inserted into an axially extending key groove 11 formed on the outer diameter side of the motor housing 1. The stator core 2 is fixed to the motor housing 1 by a fixture 3 that penetrates the key 21 axially and reaches a flange 12 formed at the axial end of the motor housing 1.

[0016] Thus, since the stator core 2 of the present invention is fixed to the motor housing 1 by the fixture 3, it is possible to prevent displacement against tensile force in the outer diameter direction and torque reaction force in the circumferential direction.

[0017] Therefore, by precisely matching the dimensions of the key 21 and the key groove 12 and fitting all the keys and key grooves, it is not necessary to fix the stator core 2 to the motor housing 1. Thus, a gap can be formed between the key 21 and the key groove 12, achieving both ease of assembly and strength reliability. Moreover, it is inexpensive without the need to manufacture the key and key groove by high-precision machining.

[0018] Further, the stator core 2 is formed by axially laminating annular electromagnetic steel sheets formed by connecting fan-shaped electromagnetic steel sheets 23 in the circumferential direction.

[0019] As shown in FIG. 2, the stator core formed by laminating these annular electromagnetic steel sheets is produced by axially laminating the connection portions 24 of the annular electromagnetic steel sheets while shifting them circumferentially between adjacent annular electromagnetic steel sheets and then bonding between these annular electromagnetic steel sheets.

[0020] Therefore, one fan-shaped electromagnetic steel sheet 23 is adhered to four fan-shaped electromagnetic steel sheets in pairs on both sides on one side thereof, and the connection portions 24 are not continuous in the axial direction. Since the entire stator core 2 is integrated, the magnetic attraction force from the rotor magnet that is pulled in the outer diameter direction can be canceled out as a whole for the stator core.

[0021] That is, a certain sector-shaped electromagnetic steel sheet is pulled in the outer diameter direction by the magnetic attraction force from the magnet of the rotor. However, since the sector-shaped electromagnetic steel sheet on the opposite side across the axis from the above-mentioned sector-shaped electromagnetic steel sheet is also pulled in the outer diameter direction, the magnetic attraction force that pulls the entire stator core in the outer diameter direction can be offset. When combined with the fact that it is fixed by the above-mentioned fixture, the strength reliability can be improved.

[0022] As shown in FIG. 3, it is preferable that the sector-shaped electromagnetic steel sheet 23 has a convex portion 25 protruding in the circumferential direction and a concave portion 26 corresponding to the convex portion on the opposite side in the circumferential direction.

[0023] By fitting the convex portion 25 and the concave portion 26 of the sector-shaped electromagnetic steel sheets 23 adjacent in the circumferential direction and connecting the sector-shaped electromagnetic steel sheets to form an annular electromagnetic steel sheet, the amount of adhesive applied between the annular electromagnetic steel sheets adjacent in the axial direction can be reduced while ensuring the strength reliability. Therefore, not only can the cost be reduced, but also the electromagnetic steel sheet occupancy rate in the stator core is increased, improving the motor performance.

[0024] As shown in FIG. 3, examples of the shape of the convex portion 25 of the sector-shaped electromagnetic steel sheet include an inverted taper shape with a wide width on the side of the adjacent sector-shaped electromagnetic steel sheet, a circular shape, a wood shape, and the like.

[0025] It is preferable that the sector-shaped electromagnetic steel sheet 23 has a key 21 protruding on its inner diameter side, and the fixture 3 penetrates through all the sector-shaped electromagnetic steel sheets on the key 21 and is fixed to the motor housing 1.

[0026] Since all the sector-shaped electromagnetic steel sheets 23 constituting the stator core 2 are fixed to the motor housing 1 by the fixture 3, the strength reliability is further improved.

[0027] Examples of the fixture include bolts and lock pins. Also, when the sector-shaped electromagnetic steel sheet is an amorphous electromagnetic steel sheet, the loss can be reduced.

[0028] The stator core 2 described above includes a thin annular electrical steel sheet and an annular electrical steel sheet that is thicker than the thin annular electrical steel sheet, and it is preferable that at least the annular electrical steel sheets at both axial ends are the thick annular electrical steel sheets.

[0029] When bolts are used to secure the stator core 2 to the motor housing 1, there is a risk of damage to the electromagnetic steel sheet due to the torsional force on the bolt seating surface. By forming the electromagnetic steel sheets at both axial ends that contact the bolt seating surface and the flange of the motor housing with thicker electromagnetic steel sheets, the rigidity of the stator core 2 is increased, and damage to the electromagnetic steel sheet due to the torsional force on the bolt seating surface can be suppressed.

[0030] In addition to providing thick annular electrical steel sheets at both axial ends of the stator core 2 described above, it is preferable to also arrange thick annular electrical steel sheets in the middle of the lamination direction.

[0031] As described above, the stator core 1 of the present invention is fixed to the motor housing by the fastener 3, so that a gap is formed between the key and the keyway, improving ease of assembly.

[0032] By arranging thick annular electrical steel sheets in the middle of the lamination direction, the keys 21 of these thick annular electrical steel sheets are fitted into the keyways 12 of the motor housing 1, and a gap is formed between the keys 21 of the thin annular electrical steel sheets and the keyways 12. This prevents deformation due to internal stress even in stator cores that include the thin annular electrical steel sheets, and makes it possible to position and fix the stator core 2 with high precision.

[0033] In the case of the thick annular electrical steel sheet described above, it is not necessary to engage all of the keys and keyways arranged in the circumferential direction, but it is preferable to engage two keys and keyways that are opposite each other on either side of the shaft.

[0034] While engaging all the keys and keyways arranged in the circumferential direction can reduce the load distribution in the circumferential direction, it requires extremely high precision in terms of lamination and machining accuracy, leading to increased costs and reduced ease of assembly.

[0035] Since the two opposing keys are arranged geometrically in a straight line during machining, it is easy to improve machining accuracy, and similarly, high-precision measurement of the shape is possible, thus suppressing cost increases even when high precision is required.

[0036] Furthermore, if there are two opposing key 21s and keyways 12s to be mated, assembly is easier compared to the case where all the keys and keyways arranged in the circumferential direction are mated.

[0037] It is preferable that the keyway 12 of the motor housing, which is fitted with the key of the annular electromagnetic steel sheet, has an insert on its inner wall that is stronger than the base material constituting the motor housing 1.

[0038] Stress concentrates in the keyway 12 that is mated with the key mentioned above. However, the motor housing 1 is often made of a relatively low-strength material such as aluminum. When the motor housing is made of such a relatively low-strength material, it becomes necessary to enlarge the keyway in order to distribute the stress.

[0039] By providing a high-strength insert on the inner wall of the keyway 12, the load-bearing capacity of the keyway is improved, and the size of the keyway can be reduced, making it possible to miniaturize the motor.

[0040] Such a motor housing can be formed by press-fitting an insert made of steel or other material into a formed keyway.

[0041] It is preferable that the number of teeth 22 in the fan-shaped electromagnetic steel sheet 23 constituting the stator core 2 is not a multiple of 3.

[0042] When the above stator is used in a 3-phase (UVW) motor, if the number of teeth 22 of the fan-shaped electromagnetic steel sheet 23 is a multiple of 3, the same phase elastic deformation occurs in all of the fan-shaped electromagnetic steel sheets, which tends to increase the natural frequency and makes the sound vibration unfavorable.

[0043] For example, as shown in Figure 4, if the number of teeth 22 of the fan-shaped electromagnetic steel sheet is not a multiple of 3, and the number of poles of the fan-shaped electromagnetic steel sheet is not a multiple of the number of phases of the motor, motor vibration can be suppressed. [Explanation of Symbols]

[0044] 1 Motor Housing 11 keyways 12 flanges 2 Stator Cores 21 keys 22 Teeth 23. Fan-shaped electrical steel sheet 24 Joint 25 Convex part 26 recesses 3 Fixtures

Claims

1. A stator for an outer rotor type motor, having a stator core positioned on the outer diameter side of the motor housing, The stator core described above is formed by connecting fan-shaped electromagnetic steel sheets in the circumferential direction to create annular electromagnetic steel sheets, arranging these annular electromagnetic steel sheets with their connecting portions offset in the circumferential direction between adjacent annular electromagnetic steel sheets, and bonding these annular electromagnetic steel sheets together to form a laminated structure in the axial direction. A key protruding from the inner diameter side formed on the stator core is inserted into an axially extending keyway formed on the outer diameter side of the motor housing. A stator characterized in that the stator core is fixed to the motor housing by a fastener through which its key passes in the axial direction.

2. The above fan-shaped electromagnetic steel sheet has a convex portion that protrudes in the circumferential direction and a recess that fits into the convex portion. The stator according to claim 1, characterized in that the annular electrical steel sheet is formed by connecting adjacent fan-shaped electrical steel sheets in the circumferential direction, with their convex and concave portions fitting together.

3. The stator according to claim 2, characterized in that each of the fan-shaped electromagnetic steel plates is fixed to the motor housing by the fixing device.

4. The stator core includes a thin annular electrical steel sheet and an annular electrical steel sheet that is thicker than the thin annular electrical steel sheet. The stator according to claim 3, characterized in that at least the annular electrical steel sheets at both axial ends are thick annular electrical steel sheets.

5. The stator core further includes an annular electrical steel sheet of the above thickness in the axial middle, The stator according to claim 4, characterized in that the thick annular electrical steel sheet mentioned above includes a key fitted into the keyway of the motor housing.

6. The stator according to claim 5, characterized in that the key of the thick annular electromagnetic steel sheet is fitted with the keyway of the motor housing at two opposing locations.

7. The stator according to claim 6, characterized in that the keyway of the motor housing, which is fitted with the key of the annular electromagnetic steel sheet, has an insert on its inner wall that is stronger than the base material constituting the motor housing.

8. The stator according to any one of claims 1 to 7, characterized in that the number of teeth of the fan-shaped electromagnetic steel sheet is not a multiple of 3.

Images