SU1361655A1 - Device for commutating electric machines - Google Patents

Abstract

Plasma refers to elec. chromatin and can be used in automotive alternators. The purpose of the invention is to increase the service life by optimizing the conditions of current transfer. The device contains pod1-1zhnye and stationary contact elements. Each pair of contact elements is made in the form of outer and inner rings of the sliding bearing. Bearing rings are installed with mutual eccentricity, the value of which is e (O, 0015-0.005) d, where d is the outer diameter of the inner ring. The surface of direct contact of the elements of the contact pair is located in the angular zone o /, 100-135. In the annulus formed with each ring with an outer diameter d and a gap with an inner diameter D, the gap 9 contains lubricant 9, which also serves to compensate for thermal expansion. 2 ill., 1 tab. Phie.

Description

The invention relates to electrical engineering in terms of creating devices for switching electrical machines and can be used, for example, in automotive alternators.

The aim of the invention is to increase the service life by optimizing the current transmission conditions by ensuring the passage of a current of a given density and reducing wear on the rubbing surfaces.

Fig. 1 shows a device for switching electric machines, a longitudinal section (a variant of use in an alternator car alternator in Fig. 2 is a section A-A in Fig. 1,

The device includes a housing 1, in which along the shaft 2 there are pairs of movable 3 and 4 and fixed 5 and 6 contact elements. Each pair is made in the form of outer and inner rings of the sliding bearing. The inner rings 3 and 4 are connected to the shaft 2 of the device, which in the embodiment being described is connected to the electric machini shaft, they are mounted on an insulating sleeve 7 fixed to the shaft 2. The outer ring 5 and fixed by means of an insulating sleeve 8 in the central part of the housing 1 ,

Rings 3 and 5, 4 and & bearings are installed with mutual eccentricity. the aunt, whose value is e (0.0015. 0.005) d, where d is the outer diameter of the inner ring 3 and 4, while

the surface of the direct contact compensates for the temperature tirivaniya elements of the contact pair, the expansion of the rings that occurs when

the operation of the electric machine at high speeds, from the friction of the rings against each other, and serves to place the lubricant 9. The lubricant effect is based on the Kragelsky effect (microtransfer), characterized by a low, close to liquid, coefficient of friction at a high class clean zone d. 100-135 (FIG. 2), In the gap formed between rings 3 and 5 (with outer diameter f) OM d), 4 and 6 (inner diameter ohm D), grease 9 is placed, as which glycerin can be used , alcohol-glycerin mixture or metal cladding grease

days of compensation of the temperature expansion of the surface and almost complete exhaustion. In the housing and the sleeve 8 there are holes for felt wicks 10, which are used to supply lubricant to the area of rings 3 and 5, 4 and 6. In order to be able to resume lubrication, the holes are provided with plugs 1 I,

The dp switching device is connected to an electrical machine as follows. Ring 6 pin 12

connected to housing 1, i.e. with the mass of an electric machine, and the ring 5 - with pin 13 with a screw 14 serving

for connecting an electric machine to an external circuit and a sleeve 15 insulated from the housing 1. On the shaft 2, an excitation winding 16 is connected, connected by the inner rings 3 and 4 of the switching device by terminals 17 and 18c. Between the sleeve 8 and the housing 1 is placed ring 19, made of elastic material.

The switching device operates as follows.

When the shaft 2 of the electric machine is rotated, the rings 3 and 4 rotate with it, and the current for powering the field winding 16 is supplied by terminal 13

from the screw 14 through the fixed ring 5, the slip contact between the rings 5 and 3 and the pin 17 to the winding 16. The circuit is closed through the pin 18, the ring 4, the slip, and the contact between the rings 4 and 6 and the pin 12 to the mass of the electric machine. The tight fit of the rings 3 and 5, 4 and 6 is accomplished by the force of gravity and the centrifugal forces arising from the rotation

rotor. Possible distortions that occur during installation of the node are compensated by rings 19 of elastic material, which ensure self-centering of the node.

Thanks to the fact that a pair of rings

3 and 5, 4 and 6 are installed with eccentricity e, between the outer and inner rings in the upper part of the device there is a gap L 2е5 due to wear of the contact surfaces.

The optimal gap size is L O, 003-0, Old. The magnitudes of the eccentricity e and the angular zone of the C are selected for structural considerations, based on the need to ensure the passage of the current and the operability of the node (compensation for thermal expansion

Research institutes and lubricant placement) and confirmed experimentally.

Let us consider the choice of the interval of the eccentricity on the example of a device for automotive alternators.

All automobile generators have contact rings with a diameter of 25- 35 mm, the gap between the stator and the rotor lies within 0.5-0.6 mm, the misalignment of the rotor surface relative to the bearing seats is 0.05 mm, the misalignment of the stator seating surfaces the offset of the inner surface of the stator is 0.05 mm. Then the total displacement of the stator and the rotor relative to each other is 0.05fO ,, 1 mm. The gaps between the stator and the rotor, the misalignment of the stator and the rotor are measured before coating these surfaces. However, in order to prevent corrosion, the inner surface of the stator is coated with a FL-OZK primer and XB-125 enamel in two layers, and the rotor surface is coated with GF-92 enamel. the gap between the stator and the rotor is smaller by the total value of the coatings, i.e. 0.16-0.20 MM. Since the rotor is located midway between the bearings, with a clearance of L 0.35 mm in the switching device, the rotor displacement is O, 175 mm.

Therefore, taking into account all offsets and coatings, the minimum guaranteed clearance between the stator and the rotor is 0.5 - (0.100 f 0.200 + + 0.175) 0.025 mm. .

. As can be seen from the above reasoning, an increase in the size of the overhang L more than 0.35 mm can lead to the rotor being grazed on the stator, i.e to break the electric car. Thus, the upper limit of the size of the gap L is limited to 0.01.

The lower limit of the gap size, 0.003d, is due to the need to place the lubricant and compensate for thermal expansion.

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The results of experimental verification of the proposed device are shown in the table.

As can be seen from the table, the control zone, ensuring the operability of the device, for switching, is in the angular interval x 100-10 135 with a gap (0.003-0.0) d., I.e. with an eccentricity value (0.0015 - 0.005) d.

 TaKPiM, by optimizing the current transmission conditions — ensuring that the current flows through a given density and eliminates wear of the rubbing surfaces — increases the service life of the proposed device as compared to wear, in which due to dry friction between the bearing rings, spaced concentrically, the gap between them increases continuously, and as a result, 25 the electrical contact area decreases and the ringing of the rings increases.

Claims (1)

Invention Formula A device for switching electric machines, comprising a pair of moving and stationary contact elements located along the shaft, each of the pairs being made as external and internal, connected to the shaft, bearing rings, characterized in that the purpose of increasing service life by optimizing current transfer conditions by ensuring the passage of current of a given density and reducing wear of surfaces, rings bearings are installed with an eccentricity, the value of which is e (0.0015, .. 0.005) d, where d is the outer diameter of the inner ring, while the surface is the contacting of the elements of the pair is located in the corner zone 100-135, and in the gap formed between the rings there is a lubricant. 35 0.35 100 0.160.5 0.025 Provided normal performance I 17 16 (dtt sixteen