The present application claims priority from Japanese Patent Application No. 2012-244893, which was filed on Nov. 6, 2012, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
An embodiment disclosed relates to rotating electrical machines.
2. Description of the Related Art
The so-called direct drive type electric motor that directly drives a load without using a reduction device is known.
According to one aspect of the disclosure, there is provided a rotating electrical machine including a stator and a rotor that are arranged facing each other via a magnetic air gap, an output shaft that is coupled to the rotor and is rotatably arranged by at least one bearing, and a fan that is coupled to the output shaft. The fan includes a disc portion configured to cover an end portion of the stator in an axial direction, and a plurality of blade portions that is provided on the stator side of the disc portion so as to protrude towards the stator.
An embodiment will be described below with reference to accompanying drawings.
The configuration of a rotating electrical machine 1 according to the present embodiment will first be described with reference to
The fixed portion 2 includes a housing 4, a bottom surface bracket 5, an armature coil 6 and two thrust bearings 7. The housing 4 is substantially cylindrical as a whole, and houses therein most components included in the rotating electrical machine 1. A radial direction in the cylindrical shape of the housing 4 is hereinafter referred simply to as a “radial direction”; an axial direction in the cylindrical shape of the housing 4 is hereinafter referred simply to as an “axial direction.” The bottom surface bracket 5 integrally includes a bottom surface portion 5a having a disc shape and a fixed shaft 5b. The bottom surface portion 5a has an external diameter equal to that of the housing 4. The fixed shaft 5b is formed in the shape of a hollow tube which protrudes into the center of the bottom surface portion 5a. The fixed shaft 5b penetrates the center portion of the housing 4. The bottom surface portion 5a is fixed to block one opening portion (in a lower portion of the figure) of the housing 4. A plurality of armature coils 6 is provided so as to be aligned in a circumferential direction on the inner circumferential surface of the housing 4. The armature coil 6 corresponds to a stator that is recited in each claim.
The rotating portion 3 includes an output shaft 8, a permanent magnet 9 and a rotation cover 10. The output shaft 8, as a whole, is formed substantially in the shape of a hollow tube. A flange 8a is formed on an end portion on one side (the upper side of the figure) of the output shaft 8. With the flange 8a located in an open end side (the upper side of the figure) of the above-described housing 4, the output shaft 8 fits to the outer circumferential surface of the fixed shaft 5b. The output shaft 8 is also supported to the fixed shaft 5b through the two thrust bearings 7 (bearings). With the arrangement, with the position in the above-described axial direction constrained, the output shaft 8 is rotatably supported around an axis along an up/down direction of the figure. A plurality of permanent magnets 9 is provided so as to be aligned in the circumferential direction on the outer circumferential surface of the output shaft 8. The permanent magnets 9 are arranged so as to face the above-described armature coil 6 in the above-described radial direction through a magnetic air gap. The rotation cover 10 is a disc member that is substantially doughnut-shaped (circular) as a whole. The rotation cover 10 is attached with an unillustrated bolt or the like to the flange 8a of the above-described output shaft 8 and thus is arranged to cover the opening portion in the open end side of the housing 4. The permanent magnet 9 corresponds to a rotor that is recited in each claim.
In the rotating electrical machine 1 configured as described above, an alternating magnetic field is generated in the circumferential direction within the housing 4 by the supply of power having the same predetermined frequency to each of the armature coils 6. Then, the permanent magnets 9 of the fixed portion 2 receive an attracting force and a repulsive force caused by the alternating magnetic field to generate a torque on the output shaft 8 and thus the entire rotating portion 3 is rotated. The order of change of the predetermined frequency between the armature coils 6 is switched, and thus it is possible to switch the normal rotation and reverse rotation of the output shaft 8.
The rotating electrical machine 1 configured as described above functions as a DD motor that drives by directly coupling a load machine (a load target: not shown in particular) to the output shaft 8 without intervention of a reduction device. Consequently, a gap (or a slidable contact portion) between the body of the rotating electrical machine 1 on the side of the fixed portion 2 and the output shaft 8 is more likely to be exposed to the atmosphere. Thus, as the application of the DD motor has been diversified in recent years, a dustproof function for preventing the entry of dust and dirt into the housing 4 through the gap described above is required.
As a general dustproof configuration, as described above, other than the configuration in which the opening portion of the housing 4 is covered with the rotation cover 10, there is a configuration in which the oil seal of an elastic member provided in the fixed portion 2 is brought into slidable contact with the output shaft 8 (not shown in particular). The oil seal is advantageous only in terms of the dustproof function. However, the oil seal is disadvantages in the following respects. That is, when the oil seal is used, a loss of torque of the rotating electrical machine 1 is caused by the friction. Moreover, when the oil seal is used, the rated number of revolutions of the rotating electrical machine 1 itself needs to be set lower so as to suppress the abrasion and heat generation of a seal member. Moreover, when the oil seal is used, maintenance such as the periodical exchange of the seal member and the replenishment of a lubricant is needed. Hence, when priority is given to the performance of and the convenience of use of the rotating electrical machine 1, as in the present embodiment, the dustproof configuration using the rotation cover 10 is often applied.
The simplest configuration of a rotation cover is only a circular flat plate. Furthermore, in the configuration of a comparative example shown in
By contrast, in the present embodiment, the rotation cover 10 configured as shown in
Since the arc portion of a substantially semicircular embossing process portion 10d faces the outer side of the rotation cover 10 in the above-described radial direction. Consequently, the width of each of the blade portions 10b in the circumferential direction is increased from the inner side to the outer side in the above-described radial direction. Then, in the outermost side, the six blade portions 10b are circularly and integrally connected over the entire circumferential direction. The outer circumferential surface (the end surface on the side of the housing 4) of the circularly connected portion described above faces the inner circumferential surface of the housing 4 through a minute air gap in the above-described radial direction. Moreover, each of the blade portions 10b is formed symmetrically with respect to the rotation direction (that is, in the shape of rotational symmetry.)
According to the embodiment described above, the following effects are obtained. That is, the rotating electrical machine 1 of the present embodiment includes the rotation cover 10 that functions as a rotation fan. The rotation cover 10 includes the circular flat plate portion 10a that covers the end portion of the armature coil 6 in the above-described axial direction, and with the arrangement, it is possible to protect the armature coil 6 from external foreign matters (such as water, dust and earth and sand). The rotation cover 10 also includes a plurality of blade portions 10b that is provided to protrude toward the side of the armature coil 6 of the circular flat plate portion 10a. The blade portions 10b are rotated together with the circular flat plate portion 10a when the output shaft 8 is rotated, and generate forced convection in the circumferential direction in the air layer 110 between the armature coil 6 and the rotation cover 10. As a result, it is possible to increase a heat-transfer coefficient between the armature coil 6 and the air layer 110, and thus it is possible to increase the dissipation of heat generated in the armature coil 6.
In addition, in the rotating electrical machine 1 of the present embodiment, that the rotation cover 10 and the housing 4 are not in contact has the following significance. In other words, for example, a structure in which the circular flat plate portion 10a of the rotation cover 10 is in contact with the housing 4 is considered to be adopted so that the hermeticity of a space housing the armature coil 6 and the permanent magnet 9. However, in this case, such contact causes an increase in frictional torque to reduce the motor characteristic. Furthermore, since such contact causes the abrasion of the rotation cover 10, it is necessary to perform periodical maintenance. On the other hand, in the present embodiment, in particular, since the rotation cover 10 is not in contact with the housing 4, the motor characteristic is prevented from being reduced, and thus it is possible to avoid maintenance.
Moreover, in the present embodiment, in particular, the end faces of a plurality of blade portions 10b on the side of the housing 4 are connected over the entire circumferential direction, and the connected end surfaces face the housing 4 through the minute air gap. With the arrangement, it is possible to increase the hermeticity of the internal space housing the armature coil 6 and the permanent magnet 9 and to prevent the entry of external foreign matters. Moreover, the outer circumferential edge portion of the circular flat plate portion 10a is bent or formed otherwise, and thus it is possible to form a labyrinth structure between the rotation cover 10 and the housing 4. In this case, it is possible to further enhance the hermeticity in this case.
Moreover, in the present embodiment, in particular, each of the blade portions 10b of the rotation cover 10 is formed to be rotationally symmetrical. With the arrangement, even when the rotating electrical machine 1 is driven in a normal rotation direction or a reverse rotation direction, it is possible to equally perform the cooling function by the rotation cover 10.
In a so-called direct drive type rotating electrical machine 1, since the output shaft 8 is directly fixed to the load machine, the heat of the rotating electrical machine 1 is easily transmitted to the load target. Thus, when the heat dissipation of the rotating electrical machine 1 is low, the load machine is likely to be affected by the heat. Therefore, the present embodiment is applied to the direct drive type rotating electrical machine 1, and thus it is possible to more effectively reduce the influence of the heat by the rotating electrical machine 1 to the load machine.
The disclosed embodiment is not limited to the embodiment described above; many variations are possible without departing from the spirit and the technical idea thereof. In other words, as long as a plurality of blade portions provided in the rotation cover 10 is configured such that, when the rotation cover 10 is rotated, the air layer 110 between the blade portions and the armature coil 6 can be appropriately agitated, another configuration may be adopted. Such variations will be sequentially described below.
(1) Case where the forms of a protrusion portion and an embossing process are different
In the variations of
(2) Case where the rotation cover has a protrusion portion (radial direction)
In the embodiment described above, the inner circumferential surface of the opening portion of the housing 4 is close to the outer circular connection portion of the blade portions 10b of the rotation cover 10, and thus the labyrinth structure is formed between the rotation cover 10 and the housing 4, with the result that the hermeticity is enhanced. However, the present disclosure is not limited to this configuration; a protrusion portion that functions as the labyrinth structure may be provided in the outer circumferential edge portion of the rotation cover 10.
In other words, as shown in
According to the present variation described above, the following effects are obtained. That is, in the rotating electrical machine 1 of the present variation, the circular flat plate portion 10a of the rotation cover 10B includes the protrusion portions 10i that can form the labyrinth structure between the circular flat plate portion 10a and the housing 4. With the arrangement, it is possible to enhance the hermeticity of the space housing the armature coil 6 and the permanent magnet 9 and to effectively prevent the entry of external foreign matters. Furthermore, since it is not necessary to form the labyrinth structure with the blade portions 10b, it is possible to enhance the flexibility of the shape of the blade portions 10b.
(3) Case where the rotation cover has a protrusion portion (axial direction)
Although the protrusion portions are made to protrude in the radial direction as described above, as shown in
At this time, as shown in
(4) Others
The shape and the number of blade portions 10b and 10f are not limited to the examples described above; another shape having the function of agitating air may be adopted, and another number thereof may be provided. Although the rotation covers 10, 10A, 10B and 10C described above are expected to be formed by cutting, for example, a cold-rolled steel, they may be formed of a material such as a resin.
Although, in the embodiment and each of the variations described above, the motor has been described as the rotating electrical machine, they may be applied to a generator having the same configuration.
In addition to what has been described above, the embodiment and each of the variations described above may be combined as necessary and utilized. In addition, although unillustrated, in the embodiment and the each of variations described above, various modifications are possible without departing from the spirit thereof.
Number | Date | Country | Kind |
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2012-244893 | Nov 2012 | JP | national |