RU2516266C2 - Method for isolation of magnet core slots in motor armature - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in the method for insulation of slots of the magnet cores in micromotor stators based on charging of electroinsulating material particles with electric charge and their precipitation into slots under action of the electric field, the new development lies in placement of the armature magnet cores in the centre of an elastic cylindrical dielectric cup that covers hermetically the outer surface of the armature magnet core, installation of two electrodes at a distance of 20-30 mm from end walls of the armature magnet core, filling of the above cup with electrophoretic compound with the following ratio of components (in mg/l): varnish PE-939 of C mark - (510÷255), 1% - liquid ammonia 1% - NH₄OH - (130÷190), ethyl cellosolve - C₄H₁₀O₂ - (120÷175), diethylene oxide (C₄H₈O₂) - the rest. Positive potential from the direct current source is supplied to the magnet core and negative potential from the above source is supplied to electrodes and at current density within the range of 2-10 mA/cm², electrophoretic precipitation of the film former is made to the slots, to end surfaces and a shaft of the magnet core armature within the period of rime defined as per the formula $$t=\frac{cd}{kj},$$

where c is density of enamel, kg/m³, d is thickness of slot insulation, m, k is current output solid residual, kg/A×s. In process of electrophoretic precipitation of the film former continuous rotation of electrophoretic compound is arranged opposite each slot at the end wall of the armature magnet core, for this purpose rectangular permanent magnets are placed opposite each slot and their end walls are placed from the magnet core end at the distance of 5-10 mm. When t time is over the armature magnet core is removed from electrophoretic compound and the film precipitated at the surface of the magnet core is subject to thermal treatment during 4-5 minutes at a temperature of 380-390°C. Insulation of the armature magnet core slots for electric motor AIR71V8 according to the claimed method allows attaining the technical result at thickness of the slot insulating film much thinner than thickness of the film obtained by the prototype method.

EFFECT: increase of breakdown voltage of the film 1,4 timers more than the breakdown voltage of the film obtained by the prototype method, receipt of higher, a sequence higher, adhesive and mechanical properties of the film with simultaneous reduction of labour intensity during slots isolation per 38 times.

3 dwg

Description

The invention relates to electrical engineering, in particular to methods for isolating the grooves of the stators of electric machines.

A known method of isolating the magnetic cores of anchors, which includes three main processes: 1) isolation of the grooves; 2) shaft isolation; 3) insulation of the frontal parts of the steel anchors [1]. In accordance with the specified method for isolating the grooves, cutting of the groove insulation (boxes) is preliminarily carried out. The groove insulation (boxes) are cut so that the insulation inserted into the grooves of the armature protrudes beyond the steel by 1-2 mm in each direction. Insulated boxes embedded in the grooves are crimped in place with wooden mandrels, after which their sides are tight, abut against the walls of the grooves. This eliminates the possibility of tearing the boxes, especially at the corners, when upsetting the winding with wedges.

To insulate the rear side of the shaft from the side opposite to the collector, where the winding can come into contact with it, an insulating tube of Bakelized paper is put on the shaft. The shaft on the collector side must be insulated with two to three layers of varnish.

To protect the frontal parts of the winding, they are fixed with a piece of cambric. The cambric is put on the shaft, wrapped around it and secured with a cord. At the end of the winding, the anchors wrap the frontal parts of the winding with the ends of the cambric and put them into the grooves under the wedges that secure the winding.

The disadvantage of this method of manufacturing the groove insulation of the magnetic cores of the motor anchors is that when laying the boxes in the grooves, and then placing the motor windings in them, two air gaps are formed between the winding, the housing insulation and the magnetic core: one between the winding and the groove insulation, and the other - between the groove insulation and the magnetic core, which affects the heat sink from the winding into the magnetic core. The thickness of the material from which the groove box is made is relatively large, which leads to inefficient use of the grooves, and, as a result, to a decrease in the fill factor of the groove with the wire, to a decrease in the power of electric motors and an increase in their dimensions. In addition, the performance of this method of isolating the grooves is low, due to the need for sequential placement in each groove of the winding of the duct groove insulation, and because of the impossibility of group isolation of grooves simultaneously in several windings. Low productivity is also due to the fact that all the operations of isolating the anchors of electric motors of low power have to be carried out manually, due to the small size of the grooves of the anchors of these machines. The fact that the isolation of the grooves, the isolation of the shaft and the insulation of the frontal parts of the steel, the anchors produce not simultaneously, but sequentially, also leads to a decrease in productivity.

There is also a known method of manufacturing a groove insulation of magnetic cores of stators by spraying from an epoxy powder to isolate heat resistance classes B and F or polyamide ether powders for insulation of class H [2]

The prototype method consists in immersing a cold magnetic core in a layer of epoxy resin powder or polyamide ether powders under the influence of a high voltage current discharge. The polymer particles are charged, and under the action of electric forces it moves to the oppositely charged product - the magnetic core and is deposited on its surface. The magnetic core is removed from the spraying chamber and the sprayed powder is removed from the entire surface of the magnetic core, except for the grooves. The powder remaining in the grooves is subjected to a high-temperature effect, during which the polymer is melted and an insulating coating is formed. After melting the powder, the magnetic core is cooled and again placed in a layer of epoxy powder. The process of isolating the grooves is completed after 7-8 such cycles.

The disadvantage of the prototype method is the need to use high voltage to ignite an electric discharge in powder. In addition, the deposition in this way occurs not only in the grooves of the stator, but also on all other parts of the magnetic core, which leads to the need to remove the magnetic core from the powder and remove its excess from the surfaces of the magnetic core, leaving it only in the grooves of the magnetic core. This leads to unreasonably high costs of the sprayed powder, and to increase the complexity of the isolation operation, due to the need to introduce an additional cleaning operation of the sprayed powder from the surface of the magnetic core. Since in one cycle a thin layer of powder is deposited on the surface of the groove, which, after melting it, does not allow obtaining the electric strength required for groove insulation, this cycle has to be repeated 7-8 times. Due to this, the process of isolating the grooves of one magnetic core is inefficient, since it lasts for 3-4 hours. In addition, the sprayed multilayer groove insulation of the powder is very fragile, which, as a rule, excludes the possibility of mechanized winding of the windings and they have to be laid manually in the grooves.

The technical problem to which the present invention is directed is to increase the performance of groove isolation technology, to improve the quality of groove insulation and motor stators, and to simplify the method.

The problem is solved in that in the method of isolating the grooves of the magnetic cores of the micromotor anchors, based on giving the particles of the insulating material an electric charge and depositing them into the grooves under the influence of an electric field, the magnetic core of the armature is placed in the center of an elastic cylindrical dielectric cup hermetically covering the outer surface of the magnetic core of the armature , install two electrodes at a distance of 20-30 mm from the ends of the magnetic core of the armature, pour into the said glass lektroforetichesky composition, the following relationships electrophoretic composition of components (ml / l):

varnish PE-939 grade B - (510 ÷ 255),

1% ammonia 1% -NH ₄ OH - (130 ÷ 190),

ethyl cellosolve - C ₄ H ₁₀ O ₂ - 120 ÷ 175)

dioxane (C ₄ H ₈ O ₂ ) - the rest,

, где c - плотность эмали, кг/м³, d - толщина пазовой изоляции, м, k - выход сухого остатка по току, кг/А×сек, причем, в процессе электрофоретического осаждения пленкообразующего напротив каждого паза с торцевой части магнитного сердечника якоря создают непрерывное вращательное движение электрофоретического состава, для чего помещают напротив каждого паза прямоугольные постоянные магниты, торцы которых удалены от торца магнитного сердечника на 5-10 мм, затем после истечения времени t магнитный сердечник якоря извлекают из электрофоретического состава, и осажденную на поверхность магнитного сердечника якоря пленку подвергают термообработке в течение 4-5 минут при температуре 380-390°C.apply a positive potential to the magnetic core, and a negative potential from the constant voltage source to the electrodes, then gradually increase the voltage supplied from the mentioned source and at the same time continuously measure the electrophoresis current, and stop changing the voltage when the current reaches the electrophoresis value I = jS, where j - current density electrophoresis, lying in the range of 2-10 mA / cm ^2, S - surface area of the magnetic core of the armature, on which a film is deposited, and when said current I carried on the electrophoretic azhdenie film-forming substance into the grooves on end faces of the magnetic core and the armature shaft over time is determined from the expression

, where c is the density of enamel, kg / m ³ , d is the thickness of the groove insulation, m, k is the current output of the dry residue, kg / A × sec, and, during the electrophoretic deposition of the film-forming opposite each groove from the end of the magnetic core of the armature create a continuous rotational movement of the electrophoretic composition, for which rectangular permanent magnets are placed opposite each groove, the ends of which are 5-10 mm away from the end of the magnetic core, then after the expiration of time t, the magnetic core of the armature is removed from the electrophoretic about the composition, and the film deposited on the surface of the magnetic core of the armature is subjected to heat treatment for 4-5 minutes at a temperature of 380-390 ° C.

Figure 1 presents the implementation diagram of the proposed method. Figure 2 schematically shows the end face of the magnetic core in a dielectric glass. Figure 3 schematically shows a magnet holder. Figure 1, figure 2 and figure 3 serve to explain the essence of the invention.

In figure 1, figure 2 and figure 3 introduced the following notation:

1 - magnetic core; 2 - grooves; 3 - shaft; 4 - end face of the magnetic core; 5 - dielectric glass; 6 - lower electrode; 7 - dielectric sleeve; 8 - upper electrode-flange; 9 - permanent rectangular magnets; 10 - holder of magnets, 11 - hole of the upper electrode-flange; 12 - corrugations, for fixing the magnet holder; 13 - a constant voltage source; 14 - ammeter.

In Fig. 2 and Fig. 3, the same designations are introduced as in Fig. 1, except for position 15 in Fig. 3, which indicates the protrusions on the inner surface of the magnet holder, in the slots of which are fixed permanent rectangular magnets 9.

The invention consists in the following.

The insulation of the windings of an electric machine is one of its most important elements. It should possess simultaneously a whole range of properties: heat resistance, heat resistance, high electrical and mechanical strength, resistance to the effects of impregnating compounds, manufacturability.

In the process of manufacturing insulating structures, insulating windings and laying them in grooves, the insulating material can be cut, bent, molded, glued, baked, impregnated, etc. In this case, the material should not tear, crack, delaminate, thin, lose its mechanical and electrical strength.

Currently, the most common method of isolating the grooves of the magnetic cores of the stators of electric machines is the method in which groove ducts made of insulating film are laid in the grooves. This method allows you to mechanize the process of isolation, but has a number of disadvantages mentioned above. This method is usually used for large stators. In micromotors, in which the size of the slot of the groove is close to a millimeter, and in short-circuited anchors, in which there are no slots at all, the process of isolating with tape is very difficult, so the isolation of such motors is carried out manually, which leads to low labor productivity.

The disadvantages of the prototype method are indicated above. We, however, to eliminate the shortcomings of analogues and the prototype method, it is proposed to use the electrophoretic deposition of the insulating film in the grooves of the magnetic core of the anchors, on the shaft part, and on the ends of the magnetic core, followed by baking of this film.

Electrodeposition as a method of obtaining coatings found industrial application around the mid-60s. The rapid spread of this method is associated with a number of advantages, of which the most significant are:

a) high uniformity of the resulting coatings in thickness and its relative independence from the configuration and dimensions of the product;

b) higher corrosion resistance of the deposited films in comparison with films obtained in the traditional way;

c) high efficiency with a sufficiently large productivity;

d) the ability to control the thickness of the films by changing the current density or potential;

e) the growth rate of coatings;

g) the ability to automate the process and conduct it under ordinary conditions (room temperature and normal pressure).

Electrochemical polymer coatings are one of the areas of modern development of paint and varnish technology.

The practical use of electrochemical polymer coatings is constrained by insufficient knowledge of the processes of film formation on the substrate.

The method of applying enamel insulation is as follows. An article is immersed in a bath with an electrophoretic composition, to which one of the poles of a direct current source is connected. Under the influence of a constant electric field in a medium with high dielectric constant, ions or ionized micelles of the film former are transferred in the direction of the applied field (to the product). The deposition of film-forming material begins on the sharp edges and protrusions of the product, the charge density on which is the highest. As the deposited layer increases, the field lines of force are redistributed, and a film of uniform thickness covers the entire product.

The precipitate output depends on the duration of electrodeposition and on the amount of absorbed electricity and is limited by the electrical resistance of the resulting layer. As the thickness of the coating increases, it initially increases linearly with the deposition time, then, upon reaching a certain critical film thickness, which depends on the composition properties, the current density decreases and the electrodeposition rate decreases. Therefore, electrodeposition can be considered as a process with self-regulating values of the thickness and continuity of coatings.

The film-forming polyion in the composition should carry a charge opposite in sign to the charge of the product. Accordingly, electrodeposition at the anode, or anode deposition (anaphoresis), and electrodeposition at the cathode, or cathode deposition (cataphoresis) are distinguished.

The main advantage of electrophoretic enameling of wires, in comparison with traditional enameling methods, is the possibility of applying uniform insulation of the required thickness in one cycle, including at the sharp corners of the products, since the thickness of the applied coating is easily controlled by changing the voltage and electrodeposition time applied to the electrodes.

The main characteristics of electrophoretic systems are: dissipating ability, conditional current output, electrical conductivity.

By scattering power is understood the property of a paint and varnish material to penetrate into inaccessible places of products and to form coatings uniform in thickness. The scattering ability depends on the electrodeposition mode and on the composition of the material (film-forming, solvent, electrolyte, etc.).

The conditional current output shows how much paint material is deposited on the surface of the product when a certain amount of electricity flows. This indicator is important for estimating energy costs.

Electrical conductivity is a value that shows the ability of a paint and varnish material to conduct electric current. It depends on the nature of the film-forming, pH (acidity) and temperature of the composition. Since there is no unified theory of electrophoresis, the search for compounds with electrophoretic properties and the development of electrophoresis are carried out experimentally.

To insulate the wires of electric motors for heat resistance corresponding to class F (155 ° C) or class H (180 ° C), the most common in the domestic cable industry electrical varnish insulating PE-939 TU 16-504.026-74 is used.

In the initial state, PE-939 varnish does not have electrophoretic properties, and it is applied to the surface of a moving wire in successive layers, passing the wire through an enamel and gauge application unit of the appropriate diameter. Each layer of the applied enamel film is subjected to heat, during which the film is cured.

In our opinion, the use of class F electric motors (155 ° C) or class H (180 ° C) for insulating the grooves of the magnetic cores of the stators of the stators is advisable to use the same varnish PE-939, which is used to enamel the wires, since in this case the thermal characteristics are such as the coefficient of thermal expansion, the wires and case insulation will be the same, which should lead to increased reliability of the insulation of the electric motor. PE-939 varnish is produced in three grades A, B and C, differing in viscosity, which is determined by the amount of film-forming in it. The most viscous is varnish PE-939 grade B.

The determination of the optimal component ratio in the electrophoretic composition was carried out experimentally, using the theory of experimental design. It was found that the process of electrodeposition of enamel insulation can be implemented with the following ratios of the components of the electrophoretic composition (in ml / l):

varnish PE-939 grade B - (510 ÷ 255),

1% ammonia 1% -NH ₄ OH - (130 ÷ 190),

ethyl cellosolve - C ₄ H ₁₀ O ₂ - (120 ÷ 175)

dioxane (C ₄ H ₈ O ₂ ) - the rest.

The electrophoretic deposition of the film-forming occurs at all the indicated ratios of the components. The output of the concentration of the components of the electrophoretic composition beyond the indicated ranges leads to a decrease in the quality indicators of enamel insulation (film uniformity, electrical and mechanical strength, etc.).

With the indicated ratio of the components of the electrophoretic composition, the value of the obtained thickness of the electrophoretic film depends on the current density of the electrophoresis and the time of electrodeposition. It was found that high-quality films are obtained in the range of current densities from 2 mA / cm ² to 10 mA / cm ² . At current densities of less than 2 mA / cm ^{2, the} film becomes loose, and the quality of enamel insulation is deteriorating. An increase in current densities over 10 mA / cm ² leads to increased dissolution of the wire material, to defect formation in the deposited film, which also affects the quality of enamel insulation.

The time of the electrodeposition of the film-forming depends on the current density and the required film thickness. Consider the process of applying enamel insulation in more detail.

.The mass m of the film-forming substance deposited on a metal base is directly proportional to the charge q passing through the electrophoretic composition:

.

, где k - выход сухого остатка пленкообразующего по току, кг/А×c, ток электрофореза J, А; и t - время электрофореза, с.In its turn

where k is the yield of dry film-forming residue in current, kg / A × c, electrophoresis current J, A; and t is the time of electrophoresis, s.

.Substituting the expression (2) in the formula (1), we obtain:

.

We express the current J through the product of the current density j by the area S of the surface part of the wire immersed in the electrophoretic composition:

, где S - площадь магнитного сердечника, на которую осаждают пленку, м².

where S is the area of the magnetic core onto which the film is deposited, m ² .

Substituting expression (4) into expression (3) we obtain:

, где с - плотность эмали, кг/м³; d - толщина эмалевой изоляции, м, V - объем изоляционной пленки.On the other hand, the mass m of the enamel film of area S of the magnetic core can be determined by the formula:

where c is the density of enamel, kg / m ³ ; d is the thickness of the enamel insulation, m, V is the volume of the insulating film.

.Equating the right parts of expressions (4) and (6) to each other and, transforming the expression obtained, with respect to the time of electrophoresis t, we obtain:

.

For better penetration of the electrophoretic composition into the grooves of the armature, opposite to each groove from the end part of the magnetic core of the armature, a continuous rotational movement of the electrophoretic composition is created, for which rectangular permanent magnets are placed opposite each groove, the ends of which are 5-10 mm from the surface of the grooves. The continuous rotational motion of an electrically conductive fluid during the flow of electric current in a liquid around the corners of a rectangular magnet was discovered by G. Nikolaev and described in [3]. The electrophoretic composition is an electrically conductive fluid, and the process of electrodeposition is accompanied by the flow of current in the fluid. The establishment of permanent rectangular magnets 9 (FIG. 1, FIG. 2, FIG. 3) opposite each of the anchor slots not only contributes to better penetration of the film-forming magnetic core into the grooves, but also creates additional positive effects: it increases the film-forming current output, which leads to accelerating the process of insulating the magnetic core, and in addition, the insulation film deposited in the magnetic field on the surface of the magnetic core has a higher mechanical and electrical strength than a film of the same thickness, of the same composition deposited on the surface of the magnetic core in those modes, but without affecting the process of electrodeposition by a magnetic field. The choice of the distance of the ends of the magnets from the end of the magnetic core (5-10) mm is due to the following circumstances. A distance of less than 5 mm is difficult enough to ensure when assembling the device due to the variation in the size of the magnets, and the equipment of the device. With a distance of more than 10 mm, the effectiveness of the use of magnets decreases.

An example of a specific implementation.

According to the claimed method, the grooves of the magnetic core of the armature of the AIR71 B8 electric motor were insulated, by the rated power Рн = 0.25 kW. The number of poles, 2p = 8.

The magnetic core 1 of the anchor was placed in an elastic airtight cup 5, (see figure 1) made of oil-resistant rubber "Elastosil R 502/80", so that the said cup fits snugly on the outer surface of the magnetic core. Placing the magnetic core in a sealed cup 5 made it possible to prevent electrodeposition of the insulating film on the forming surface of the magnetic core 1, which made it possible to eliminate the unproductive costs of the electrophoretic composition, reduce the electrophoresis current, and exclude the subsequent operation of cleaning the said surface from the electrophoretic insulation film deposited on it.

On the inner surface of the cup 5, at a distance of 25 mm from the ends of the magnetic core, two protrusions were made in the form of corrugations 12 (Fig. 1) between which the magnet holders 10 were placed. The magnet holders 10 (see Fig. 2) were made in the form of a steel ring, outer diameter which was equal to the diameter of the magnetic core and amounted to 80 mm. On the inner forming surface of the magnet holder ring, protrusions were made in the amount of 36 pieces, in the slots of each of which there was a permanent rectangular neodymium magnet 9 with a cross section of (3 × 3) mm ² and a length of 20 mm. The thickness of the plate from which the magnetic holders 10 were made was 5 mm. Permanent rectangular magnets 9 were located in the glass in such a way (Fig. 1, Fig. 2) so that the end of each of them was above the corresponding groove of the magnetic core of the armature. The distance between the end of the groove 4 and the ends of the magnets 9 was equal to 7 mm The shaft 3 of the magnetic core passed along the central axis of the magnetic holders 10. The shaft 3 extending from one end 4 of the magnetic core 1 (shown in figure 1 below) was inserted into the dielectric sleeve 7, in the recess of the lower electrode 6. The output of the lower electrode 6 to the outside was carried out through the hole in the dielectric cup 5. The diameter of the aforementioned terminal of the lower electrode 6 was slightly larger than the diameter of the hole in the cup, due to which a hermetic seal was made at the exit point of the electrode outlet, which prevented further leakage electrophoretic composition from a glass to the outside. The shaft 3 emerging from the other end 4 of the magnetic core 1 (shown in figure 1 above) freely exited through the hole 11 in the upper electrode-flange 8.

The distance δ from the ends 4 of the magnetic core 1 of the armature to the lower electrode 6 and the upper electrode-flange 8 was selected in the range of 10-20 mm The choice of this range of distances is due to the following reasons. When the distance δ from the ends of the magnetic core to the electrodes is less than 10 mm, the scattering ability of the composition sharply decreases, which affects the quality of the insulating film in the grooves of the magnetic core. When the distance δ from the ends of the magnetic core to the electrodes is greater than 20 mm, the energy costs necessary for the implementation of the proposed method increase, since with increasing distance the resistance of the electrophoretic composition between the electrodes and the magnetic core increases, and to provide a predetermined electrophoresis density in the gap, the higher the voltage, the higher the specified density of electrophoresis is required. We have chosen the distance δ = 15 mm.

The glass 5, with a magnetic core 1 placed inside it, magnet holders 10 and magnets 9, was mounted vertically, as shown in FIG. Through the hole 11 in the upper flange of the electrode 8 was poured into the glass electrophoretic composition, with the following composition and concentration of components (in ml / l):

varnish PE-939 grade B - 382,

1% ammonia 1% -NH ₄ OH - 160,

ethyl cellosolve - C ₄ H ₁₀ O ₂ - 147,

dioxane (C ₄ H ₈ O ₂ ) - the rest,

A positive potential was applied to magnetic core 1 from a constant voltage source 13, and a negative potential from said constant voltage source was applied to the output of the lower electrode 6 and the output of the lower electrode-flange 8, and electrophoretic deposition was performed at a current density j = 6 mA / cm ² film-forming substance grooves of the magnetic core 1 of the stator. In order to ensure electrophoresis current densities j = 6 mA / cm ^{2, we} acted as follows. Based on the dimensions of the magnetic core of the stator of the AIR71V8 electric motor, the surface area S of the magnetic core of the armature was calculated, onto which it was necessary to deposit an insulating film of one groove S ₁ by electrophoresis. The surface S was equal to:

S = 36S ₁ + 2S ₂ + (St-36Sp-2Sv), where S ₁ is the inner surface of one groove; S ₂ - the film-coated surface of one end of the shaft; St - the area of the end face of the magnetic core; Sp - the cross-sectional area of the groove; Sв - cross-sectional area of the shaft.

The dimensions of the magnetic core of the armature of the AIR71V8 electric motor, necessary to calculate the surface area of the magnetic core of the armature, onto which the insulating electrophoretic film is deposited:

Shaft diameter Dв = 19 mm;

shaft length Lв = 40 mm on each side of the end of the magnetic core;

The length of the magnetic core Lс = 80 mm;

The number of grooves Z1 = 36;

The groove perimeter in its groove section P = 19.7 mm;

The outer diameter of the magnetic core Dя = 77.5 mm;

The transverse cross-sectional area of the groove is Sp = 40.82 mm ² = 0.41 cm ² .

S ₁ = P × Lc = 19.7 × 80 = 1576 mm ² = 15.76 cm ² ;

S ₂ = p × Db × Lb = 3.14 × 19 × 40 = 2386.4 mm ² = 23.864 cm ² ;

St = p × Dя = 3.14 × (77.5) ² = 18859.625 mm ² = 188.6 cm ² ;

SB = p × (Dv) ^2/4 = 3,14 × 19 ^2/4 = 283.385 mm = 2.83 cm ^2.

S = 36S ₁ + 2S ₂ + (St-36Sp-Sv) = 36 × 15.76 + 2 × 23.864 + (188.6-36 × 0.41-2 × 2.83) ≅567.4 + 47, 7+ (188.6-14.76-5.66) ≅783.3 cm ²

The total current of electrophoresis, necessary for the implementation of electrodeposition in the grooves, on the shaft and the end face of the magnetic core of the armature is

I = j × S = 6 × 783.3 = 4699.68 mA 4 4.7 A.

When a constant voltage source 13 was connected between the magnetic core 1 and electrodes 6 and 8, the electrophoresis current I was measured with ammeter 14, and the voltage at the constant voltage source was changed until the electrophoresis current I took a value of 4, 7 A. The value of I = 4 , 7 A indicated that the electrophoresis current density j = 6 mA / cm ² = 6 × 10 ^-3 × 10 ⁴ = 60 A / m ² .

The process of electrophoretic deposition of an insulating film on the surface of the grooves was performed for a time t, which was calculated from the expression:

.

.

The thickness of the insulating film d was set based on the average breakdown voltage of the polyethylene terephthalate PET-E film with a thickness d _of = 0.25 mm used in a typical technology for manufacturing slot insulation, which turned out to be 4.5 kV. In order to ensure that the groove insulation that we produce does not inferior in breakdown voltage to the typical groove insulation of the AIR71V8 stator magnetic core, we set the breakdown voltage to 6 kV. Such a breakdown voltage had a film with a thickness of d = 20 μm = 20 × 10 ^-6 m deposited by us using the proposed method.

Based on a given thickness of enamel insulation 25 × 10 ^-6 m, enamel density c = 2.5 × 10 ³ kg / m ³ , the output of the dry residue by current k = 9.87 × 10 ^-6 kg / m ² , current density j = 6 mA / cm ² = 6 × 10 ^-3 × 10 ⁴ = 60 A / m ² determined the time t of electrophoresis.

.

.

The film deposited in the grooves of the stator magnetic core was heat treated for 4.5 minutes at a temperature of 385 ° C.

The deposition of epoxy powder in the prototype method into the grooves of the magnetic stator core of the AIR71V8 stator was carried out in 8 cycles, each of which was 30 minutes The total duration of the process of isolating the grooves of one engine was 4 hours. The resulting layer of insulating film of the groove insulation of the epoxy powder was 0.2 mm The average breakdown voltage was 4.3 kV. The adhesion of the film obtained by the present method, and its mechanical characteristics were almost an order of magnitude higher than the adhesion and mechanical characteristics of the film obtained by the prototype method.

In the inventive method eliminates the need for high voltage, which greatly simplifies it compared with the prototype method.

Thus, the insulation of the grooves of the magnetic cores of the stators of the AIR71V8 electric motor according to the claimed method made it possible, with the thickness of the insulation film of the groove insulation almost an order of magnitude thinner than the thickness of the groove insulation film obtained by the prototype method, to obtain a 1.4 times higher breakdown voltage, than the breakdown voltage of the film obtained by the prototype method, to obtain higher, almost an order of magnitude, adhesive and mechanical characteristics, and to reduce the complexity of isolation by 38 times.

Sources of used literature:

1) http://www.tehnoinfa.ru/obmotka/89.html

2) http://www.oifn.ru/notation/proizvodstvo/35/ - prototype

3). Nikolaev G.V. Modern electrodynamics and the reasons for its paradox. Prospects for building consistent electrodynamics. - Tomsk: Publishing House "Stronghold", 2003, p.44.

Claims (1)

A method of isolating the grooves of the magnetic cores of the electric motor anchors, based on giving the particles of electrical insulation material an electric charge and depositing them into the grooves under the influence of an electric field, characterized in that the magnetic core of the armature is placed in the center of an elastic cylindrical dielectric glass hermetically covering the outer surface of the magnetic core of the armature two electrodes at a distance of 20-30 mm from the ends of the magnetic core of the armature, pour into the said glass troforetichesky composition, the following relationships electrophoretic composition of components (ml / l):
varnish PE-939 grade B - (510 ÷ 255),
1% ammonia 1% -NH ₄ OH - (130 ÷ 190),
ethyl cellosolve - C ₄ H ₁₀ O ₂ - (120 ÷ 175),
dioxane (C ₄ H ₈ O ₂ ) - the rest,
apply a positive potential to the magnetic core, and a negative potential from a constant voltage source to the electrodes, then gradually increase the voltage supplied from the mentioned source, and at the same time continuously measure the electrophoresis current, and stop changing the voltage when the current reaches the electrophoresis value I = jS, where j is the current density of an electrophoresis lying in the range of 2-10 mA / cm ² , S is the surface area of the magnetic core of the armature onto which the film is deposited, and when the current I is mentioned, an electrophoretic the deposition of the film-forming substance in the grooves, on the end surfaces and the shaft of the magnetic core of the armature for a time determined from the expression $$t=\frac{cd}{kj}$$

Where c - density of enamel, kg / m ^3, d - the thickness of the slot insulation, m, k - yield dryness current, kg / A × s, and in the process of electrophoretic deposition of a film-forming opposite each groove on the end portion of the magnetic core of the armature create continuous rotational movement of the electrophoretic composition, for which rectangular permanent magnets are placed opposite each groove, the ends of which are 5-10 mm away from the end of the magnetic core, then after the expiration of time t, the magnetic core of the armature is removed from the electrophoretic about the composition, and the film deposited on the surface of the magnetic core of the armature is subjected to heat treatment for 4-5 minutes at a temperature of 380-390 ° C.

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