Electric Motor

Abstract

To improve water-proof, dust-proof, corrosion-proof, and rust-proof effects in an electric device.SOLUTION: An electric motor 100 includes: an electric motor body 101 having a metallic housing 101a; and an output shaft 102 provided at the electric motor body 101. The housing 101a includes: a substantially cylindrical housing 103 which houses a stator; and covers 104 which are detachably provided at both ends of the housing 103 and support the output shaft 102 inserted into the covers 104, and has a substantially column shape as a whole. In the electric motor 100, a polyurea layer 106 is provided on a surface of the housing 101a including a fixed base 105. Joint lines 107 between the housing 103 and the respective covers 104 are formed on the surface of the housing 101a, and the polyurea layer 106 is provided so as to cover the joint lines 107.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to electric motor Regarding. [Background technology]

[0002] Electrical equipment such as electric motors and transformers used in industry are installed in a wide range of environments, and may be used in environments where water, atmospheric gas, mist, dust, etc. are present. Conventionally, the surface coating of electrical equipment has mainly been made of thinner or polyurethane-based paints, which have problems with the thickness, strength, and flexibility of the coating film. Therefore, the coating film is easily damaged by the intrusion of water, atmospheric gas, mist, dust, etc. (hereinafter referred to as flooding, etc.), the impact of dust, etc., and erosion, and there is a risk that the progression of corrosion from rust will be accelerated.

[0003] Patent Document 1 discloses a method for repairing a liquid tank, in which a primer is applied to the painted portion, and then a sprayable instant-curing resin (such as a polyurea resin) is sprayed onto the painted portion. Patent Document 2 discloses that in an electromagnetic lifter for moving high-temperature materials, the coil is insulated from the outside and inside by spray painting with a waterproof product, for example polyurea or other equivalent resin. Patent Document 3 discloses that a polyurethane-polyurea resin is applied as a protective coating to a CNT-coated flat heater for melting snow and preventing freezing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-101527 A [Patent Document 2] Special Publication No. 2017-519701 [Patent Document 3] JP 2019-125488 A Summary of the Invention [Problem to be solved by the invention]

[0005] None of Patent Documents 1 to 3 takes measures against submersion of electric equipment such as electric motors or transformers, collision with dust or the like, corrosion, or rust.

[0006] The present invention relates to electric motor The purpose of this invention is to improve the waterproof, dustproof, corrosion-proof and rust-proofing effects in the above-mentioned products. [Means for solving the problem]

[0007] The electric motor of the present invention comprises an electric motor body having a metal case, and an output shaft provided on the electric motor body, the case comprising a substantially cylindrical housing for accommodating a stator, and a cover provided at an end of the housing for inserting and supporting the output shaft, and a surface of the case and a surface of a fin provided on the housing. The present invention is characterized in that a polyurea layer is provided on the Effect of the Invention

[0008] According to the present invention, electric motor It can improve the waterproof, dustproof, corrosion-proof, and rust-proofing effects in the [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an electric motor according to an embodiment; [Diagram 2] FIG. 1 is a characteristic diagram showing an example of the relationship between elongation and tensile strength of various coatings. [Diagram 3] FIG. 13 is a diagram for explaining the adhesion of a polyurea layer. [Figure 4] FIG. 13 is a diagram showing another type of electric motor according to an embodiment. [Diagram 5] FIG. 4 is a characteristic diagram showing an example of a temperature change of a coating film during intermittent operation. [Figure 6] FIG. 13 is a diagram for explaining an example of applying polyurea to repair a corrosion hole in a coil cover in an electric motor. [Figure 7] FIG. 2 is a diagram illustrating a transformer according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. [First embodiment] FIG. 1 shows an electric motor 100, which is an electric device according to an embodiment. In this embodiment, the electric motor 100 is used in a hot rolling line in a steelworks that is constantly exposed to water while operating. As described above, the electric motor 100 used in an environment where water, atmospheric gas, mist, dust, etc. are present has a problem that the coating film is easily damaged by the effects of water ingress, collision with dust, etc., and erosion, and corrosion from rust progresses quickly. In addition, if the electric motor 100 has a seam or hole, it is easily susceptible to water ingress, etc.

[0011] Therefore, in this embodiment, a polyurethane layer 106 is provided on the surface of the housing 101a of the motor body 101 of the motor 100, as described in detail below.

[0012] 1, the electric motor 100 includes an electric motor body 101 having a metal housing 101a made of a steel plate or the like, and an output shaft 102 provided on the electric motor body 101. The housing 101a includes a substantially cylindrical housing 103 that houses a stator, and covers 104 that are detachably provided on both ends of the housing 103 and through which the output shaft 102 is inserted and supported, and has a substantially cylindrical shape overall. In addition, a fixing base 105 for fixing the electric motor 100 is provided at the bottom of the housing 103.

[0013] In such an electric motor 100, a polyurethane layer 106 of a substantially constant thickness is provided on the surface of the housing 101a including the fixed base 105. If the surfaces of the fixed base 105 or the housing 101a have significant irregularities compared to the seams 107 or holes described below, the polyurethane layer 106 of a substantially constant thickness is provided so as to follow the irregularities. Furthermore, a seam 107 between housing 103 and cover 104 is formed on the surface of casing 101a, and polyurea layer 106 is provided so as to cover seam 107. That is, polyurea layer 106 on the housing 103 side and polyurea layer 106 on the cover 104 side are continuously connected across seam 107. Note that, although seam 107 is used as an example here, if there is a hole in the surface of casing 101a, polyurea layer 106 is provided so as to cover the hole.

[0014] On the other hand, no polyurethane layer is provided on the surface of the output shaft 102. The output shaft 102 rotates relative to the electric motor body 101, and if there was a polyurethane layer that was continuously connected from the housing 101a side to the surface of the output shaft 102, the rotation of the output shaft 102 would be hindered. Grease is filled between the bearings in the electric motor body 101 and the output shaft 102, so water does not seep in between the electric motor body 101 and the output shaft 102.

[0015] Here, polyurea is a resin compound formed by a chemical reaction between isocyanate and polyamine, and has waterproof, dustproof, anticorrosive and rustproof properties. To form a polyurethane layer 106 on the surface of the housing 101a, polyurethane is applied by brushing, which also serves as painting. At this time, the polyurethane is continuously applied so as to cover the seams 107 on the surface of the housing 101a. When the polyurethane is applied by brushing on the surface of the housing 101a, a measure may be taken such as covering the output shaft 102 with a rag to prevent the polyurethane from getting on it. Although the polyurethane is applied by brushing, it may also be sprayed.

[0016] Figure 2 shows examples of the relationship between elongation [%] and tensile strength [MPa] for various coatings. Polyurea is intermediate between the high strength (durability) of epoxy resin and the high elongation (elasticity) of polyurethane, and the polyurea layer can be said to be a coating film with highly flexible material properties that include flexibility and elasticity.

[0017] Moreover, the polyurea layer has a wide heat resistance temperature range of -30°C to 120°C, and is therefore suitable for application to the electric motor 100 used in a hot rolling line.

[0018] Moreover, the polyurea layer can maintain high adhesion. The adhesion of the polyurea layer was examined. As shown in Fig. 3, a 1 mm thick polyurea was brushed onto an iron plate 302 having a hole 301 with a diameter of 30 mm formed therein, covering and closing the hole 301, to form a polyurea layer 303. As shown in Fig. 3(a), hydraulic pressure was applied from the side where the polyurea layer 303 was provided (hereinafter referred to as outer pressure), and as shown in Fig. 3(b), hydraulic pressure was applied from the side opposite to the side where the polyurea layer 303 was provided (hereinafter referred to as inner pressure). 3(b), as the pressure increases, the polyurethane layer 303 gradually expands, and at 0.24 MPa, peeling begins in the area enclosed by the dotted line in the figure, and the expansion accelerates all at once, resulting in a loss of adhesive strength. Even if the polyurethane layer 303 expands up to about 0.24 MPa, the adhesive strength is covered by the amount of deformation of the polyurethane layer 303, and even if peeling occurs thereafter, the polyurethane layer 303 does not break due to its high flexibility. On the other hand, in the case of the external pressure shown in Fig. 3(a), the polyurethane layer 303 is pressed against the iron plate 302, does not expand at all up to 0.70 MPa, and maintains high adhesion. For this reason, when the pressure on one side of the metal surface to which the polyurethane is applied is higher than the pressure on the other side, it is preferable to apply the polyurethane to the metal surface on the side where the pressure is higher. Considering that only external pressure is applied to the housing 101a of the electric motor 100, it is effective to provide the polyurethane layer 106 for waterproofing, dustproofing, corrosion prevention, and rust prevention on the surface of the housing 101a with seams and holes.

[0019] As described above, by providing the polyurea layer 106 on the surface of the housing 101a of the motor body 101 of the motor 100, the effects of waterproofing, dustproofing, corrosion prevention, and rust prevention can be improved. Based on the experience that corrosion and rust can occur not only in water but also in dust, atmospheric gas, mist (including seawater), etc., corrosion prevention and rust prevention experiments were attempted by leaving an iron plate coated with polyurea in various environments. For example, a test iron plate coated with polyurea was placed in an acid mist environment, and a scratch was made in the polyurea layer that reached the base metal, and the plate was left for four months. After leaving the plate for four months, the polyurea layer was peeled off and visually inspected, and it was found that rust had spread around the scratch, but it was confirmed that there was no problem with rust prevention under the polyurea layer. In this way, in the motor 100 used in a hot rolling line, the effectiveness of the polyurea layer in not only waterproofing and dustproofing measures but also corrosion and rust prevention measures was confirmed.

[0020] Note that the application of polyurea is not limited to new motors, and it may be applied to motors in use. Motors are becoming smaller and thinner due to marginal design, and technology to supplement durability through repair, that is, maintenance technology for symptoms that do not appear until several years after installation, is expected. For example, if there is a corrosion perforation on the surface of the housing of a motor in use, polyurea is applied to repair it. In this way, no tools other than the application of polyurea are required on site for the corrosion perforation, and it is possible to cover the corrosion-depleted part in a short period of time.

[0021] Moreover, the electric motor 100 shown in FIG. 1 is merely one example of an electric motor, and the shape, size, etc. of the electric motor are not limited thereto. Fig. 4 shows another type of electric motor 400 according to an embodiment. The same components as those of the electric motor 100 shown in Fig. 1 are given the same reference numerals, and their description will be omitted. In the electric motor 400, a housing 101a of the electric motor main body 101 is provided with fins 401 for cooling. In this case, a polyurethane layer 106 of a substantially constant thickness is also provided on the surface of the fin 401. By providing the polyurethane layer 106 on the surface of the fin 401, it is possible to prevent damage to the fin 401 due to the collision of dust or the like caused by natural cooling air, for example.

[0022] The difference in thermal conduction was confirmed by capturing the followability of temperature changes in the coating film when the polyurea coating was 1 mm thick and when the conventional epoxy anti-corrosion coating was 0.5 mm thick, by repeating intermittent operation of the motor by running for 40 minutes and stopping for 20 minutes. As shown in Figure 5, the polyurea coating and the epoxy anti-corrosion coating were synchronized with no temperature difference in a way that immediately responded to the intermittent operation load, and the result was that there was no significant difference in thermal conduction. The tendency of temperature transition was the same with fin 401, and findings were obtained that compare favorably not only in thermal conduction but also in heat dissipation.

[0023] [Second embodiment] In the first embodiment, a form in which polyurea is applied to the surface of the housing 101a of the motor body 101 of the motor 100 has been described, but polyurea may also be applied to other metal surfaces. An example of applying polyurea to repair corrosion holes in a coil cover in an electric motor will be described with reference to Fig. 6. A stator 602 supported by a stator frame 601 and a rotor 604 connected to an output shaft 603 are installed in the electric motor. A coil cover 605 is arranged around the stator 602 to protect a coil 602b wound around a stator core 602a.

[0024] When a corrosion perforation 606 occurs in the coil cover 605, in order to repair it, polyurea is applied to the area including the corrosion perforation 606 in such a way that it covers and seals the corrosion perforation 606, thereby forming a polyurea layer 607. If the corrosion perforation 606 is large (for example, greater than 30 mm in diameter), the corrosion perforation 606 may be blocked with a backing plate 608, and then polyurea may be applied to the area including the backing plate 608 to form a polyurea layer 607. Although the coil cover 605 is shown as an example, polyurea can also be applied to repair corroded holes in components that do not require vibration resistance, such as partition plates for adjusting the airflow direction and volume inside an electric motor.

[0025] When corrosion holes occur in the coil cover inside the motor or the partition plate for adjusting the wind direction and volume, repairing them while they are still installed will have a large impact on the quality of the insulation, including maintenance powder and welding spatter, and removing and remaking them will affect the process, making it difficult to grasp the damage except during repair dismantling. Therefore, with conventional repairs, it is difficult to achieve a short construction period and a long repair cycle. In contrast, by applying polyurethane to the repair in this embodiment, no tools other than the polyurethane application are required on site, and it is possible to cover the corrosion-defected parts in a short construction period.

[0026] [Third embodiment] In the above embodiment, the electric motor is the target, but the electric equipment to which the present invention can be applied is not limited to this, and the present invention may be applied to, for example, a transformer. Fig. 7 shows a transformer 700, which is an example of an electric equipment according to the embodiment. As shown in Fig. 7, the transformer 700 is an oil-filled transformer, and includes a transformer body 701 having a metal housing 701a made of a steel plate or the like, a radiator 702 connected to a side of the transformer body 701, and a conservator 703 connected to an upper part of the transformer body 701.

[0027] In such a transformer 700, a polyurea layer 704 of a substantially uniform thickness is provided on the surface of the housing 701a of the transformer body 701, the surface of the radiator 702, and the surface of the conservator 703. In this case, too, if the surface of the housing 701a, the surface of the radiator 702, and the surface of the conservator 703 have large irregularities, the polyurea layer 704 of a substantially uniform thickness is provided so as to follow these irregularities. Also, if the surface of the housing 701a, the surface of the radiator 702, and the surface of the conservator 703 have seams or holes, the polyurea layer 704 is provided so as to cover the seams or holes.

[0028] Although the present invention has been described above with reference to the embodiments, the above embodiments are merely illustrative of the specific examples of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be embodied in various forms without departing from its technical concept or main features. [Explanation of symbols]

[0029] 100: motor, 101: motor body, 101a: housing, 102: output shaft, 106: polyurea layer, 107: joint, 401: fin, 605: coil cover, 607: polyurea layer

Claims

1. An electric motor, The motor includes an electric motor body having a metal housing and an output shaft provided on the electric motor body. The casing includes a substantially cylindrical housing that houses a stator, and a cover that is provided at an end of the housing and through which the output shaft is inserted and supported, An electric motor, comprising: a polyurethane layer provided on a surface of the housing and on surfaces of fins provided on the housing.

2. 2. The electric motor according to claim 1, wherein the polyurea layer is provided so as to cover a joint between the housing and the cover.

3. 3. The electric motor according to claim 1, wherein the surface of the output shaft is not provided with a polyurethane layer.

4. A fixing base is provided on the housing, 4. The electric motor according to claim 1, wherein the polyurethane layer is provided on a surface of the housing including the fixing base.

5. 5. The electric motor according to claim 1, which is used in a hot rolling line of a steelworks.

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