Method for manufacturing electric equipment encased in packed or sealed cover

FIELD: technology for producing electric equipment used in aircrafts, in particular ignition device of aviation gas-turbine engines and liquid rocket engines, possible use for manufacturing products with usage of foamed plastics facing increased heat resistance and heat requirements.

SUBSTANCE: during production of electric equipment encased in packed or sealed cover, internal hollow of electric equipment cover is filled with fine-dispersed foamed plastic powder, cover is aged under increased temperature during the time, sufficient for foaming and solidification of foamed plastic, cover with electric equipment elements and solidified foamed plastic located within is cooled down, packed or sealed with installation of structural lid. In accordance to invention, cover with foamed plastic is aged at increased temperature and then cooled down, both under excessive pressure of gaseous substance surrounding the cover being heated.

EFFECT: increased heat resistance and strength of electric equipment encased in packed or sealed cover.

1 dwg

 

The invention relates to a technology of manufacturing of electrical equipment used on the aircraft, in particular aggregates ignition of aircraft gas turbine engines and liquid rocket engines, and can also be used for the manufacture of products with the use of foams, which are increased requirements for heat resistance and durability.

A known method of manufacturing electrical equipment, implemented, in particular, in the manufacture of capacitive units ignition of aircraft gas turbine engines, namely, that in the case of the unit with the power connector and the high voltage output by means of clamps and fasteners: bolts, studs, screws, nuts and other set elements of the electric circuit: the voltage Converter on-Board power supply in the charging voltage of the capacitor, for example induction breaker or electronic Converter, block storage capacitor, a switching element such as a spark gap, and a resistor galvanic connection, connect them mounting actuators according to the electrical schematic set on case cover with screws or welding[1, 2, 3].

The disadvantage of the described technology solutions is a low vibration strength made it electroal the equipment - not more than 7 g. Securing constructional elements of electrical equipment (wiring diagrams) with clamps and fasteners leads, when exposed to high vibration loads from the gas turbine engine to significant cyclical reciprocal movement of the structural elements, their disintegration, destruction and failure of equipment. In addition, this manufacturing method does not provide the manufacturing units of the reduced mass due to the large number of fastening structural elements.

These shortcomings deprived of a method of manufacturing electrical equipment enclosed in a compacted or sealed wrapper, implemented, for example, in the manufacture of capacitive units ignition [4, 5], namely, that on the bottom of the housing Assembly with the power connector and the high voltage output set on the adhesive structural elements of the electric circuit: the voltage Converter catering to the charge voltage of the capacitor block storage capacitor, a switching element, the resistor galvanic coupling and other, connect them to the mounting wires, fill (fall asleep) free space between the structural elements that are installed on the bottom of the housing, powder, foam, mounted on the housing technology the cover is made not on the holes, spend the foaming and curing of the foam by heating the hull (shell) with technological lid after cooling technological remove the cover from the post through the holes in her excess cured foam, fixed on the housing hermetically cover Assembly, for example, by welding.

Use foam eliminates the relative movement between the structural elements in the shell of electrical equipment relative to each other due to their full allocation in the amount of the cured foam that provides increased their noise up to 20 g and above.

However, the disadvantage of this technological solution is the impossibility of making electrical high heat resistance when it is used to improve noise foams of low apparent density, such as PAN-AND [5, 6], providing a significant reduction in weight of aggregates at higher noise and higher.

With increasing ambient temperature higher than the temperature of the shape of light foams (90-95° (C) the gas pressure in the hermetic shell of electrical equipment in the cavity between the surface of the foam formed from contact with the process lid and structural lid shell, also increases.

This increases its Ude is inoe pressure on the surface of the foam, drawn to the cover shell, and the free surface of the foam detached from the housing unit. Under the action of high unit pressure air foam, in a hot state (above the temperature of shape), undergoes volumetric shrinkage and forms cracks (see figure 1). These phenomena result in conditions of cyclic temperature changes and excessive vibration to the disintegration of the mass of foam and, as a consequence, the mutual displacement of structural elements, mounted in the housing, and finally to the edge of the wires, their destruction and failure of equipment.

The present invention solves the problem of increasing the heat resistance and noise electrical equipment enclosed in a compacted or sealed envelope.

The problem is solved in that, unlike the prototype, the processes of heating to a temperature of foaming, holding at the temperature of curing of the foam, and cooling is carried out at elevated pressure of the gas above the surface of the foam.

Experimental studies conducted by the authors of the present invention have shown that the conduct of the processes of heating to a temperature of foaming, holding at the temperature of curing of the foam and cooling shell with the electrical equipment to the normal the temperature at a pressure gas, surrounding the shell, significantly improves the dimensional stability of the foams, their mechanical characteristics, excludes laces and cracks in the volume of the foam.

The temperature rise of shape foams and increase their strength excludes when exposed to elevated ambient temperatures, the occurrence of significant shrinkage of the foam in the shell, his tightened, the occurrence of cracks and separation of the volume of foam into separate fragments, and, consequently, eliminates the disintegration of the structural elements of the electrical equipment enclosed in a sealed and airtight membranes, and its refusal.

Below is an example of the implementation of the proposed method of manufacture of aircraft electrical equipment.

1. In the shell of electrical equipment, such as ignition unit, with tightly installed in her power connector and high-voltage pins, for example, adhesive sealant establish constructive elements of the electric circuit: the voltage Converter catering to the voltage of the charge storage capacitor, the block storage capacitor, a switching element, the resistor galvanic coupling and other

2. Fill (fall asleep) free housing shell powder foam, such as PAN-AND-150 [6], in sufficient quantity so that after foaming to ensure the Ekiti minimum mass of surplus, facing technological lid.

3. Mounted on the housing shell electrical technology the lid and put it in thermal pressure chamber.

4. Increase the ambient pressure above the shell installed on it technological lid to 0.05 MPa.

5. Spend the foaming and curing of the foam by heating, when the temperature of the environment on mode, for example,

the rise of temperature up to 80° - (20-50) min,

exposure at 80° - 1 hour,

temperature rise to 90° - (15-30) minutes,

exposure at 90° - 1 hour,

rise of temperature up to 110° - (15-30)minutes,

exposure at 110° - 2 hours.

6. Cool installed in thermal pressure chamber shell under the pressure of the working gas in thermostat 0.05 MPa.

7. Removed from the housing process cover with excess cured foam that came out through the hole in the lid in the process of foaming of the foam.

8. On the housing shell tightly fasten the cover, for example, by welding.

Comparative Autonomous tests of the capacitive ignition units, made by known [1-4] and the proposed methods of production, has shown its effectiveness to achieve the objectives of improving thermal stability of aggregates ignition to 120°and for short periods up to 170°when exposed to elevated vibration narusaku 20 g in the frequency range 5-2000 Hz.

Selection of a combination of excessive gas pressure acting on the foam, and types of lightweight foam, the temperature of the foaming and curing of the foam, which filled the shell of electrical equipment, allows to obtain different temperatures of shape, heat resistance, to adjust the mechanical characteristics of the foam and, therefore, produce the electrical equipment with the required heat resistance and strength, and also to make products with the use of foams characterized by increased heat resistance, dimensional stability and durability.

The claimed invention provides a simple means, without the use of new materials, additional structural or technological measures to improve noise and heat resistance electrical lethal devices.

The method is simple to implement universal in the sense of potential applications in various other areas of technology and production.

Sources of information

1. Unit ignition capacitive discharge SND-11-1A. Technical description and operating instructions. Publishing house "engineering", Moscow, 1969.

2. Unit ignition KNEES-222. Technical description, operating instructions and repair. Publishing house "engineering", Moscow, 1972.

3. Low-voltage Assembly system which we have ignition capacitive discharge SKN 22-2A. Technical description and operating instructions. Publishing house "engineering", 1968.

4. Unit ignition PVP-22-7. The technical installation manual GERE.

5. Mestizo, WAV. Foams PENG is a new type of foam. Series - Plastics and their application in industry. DNTP, 1974.

6. Foam PAN-AND-150. Specifications 2254-411-02068474-2003.

The method of manufacture of aircraft electrical equipment enclosed in a compacted or sealed envelope, which consists in the fact that the internal cavity of the shell of electrical equipment filled with fine powder, foam, soak the membrane at an elevated temperature for a time sufficient for foaming and curing of the foam, cool the shell with the items of electrical equipment and utverzhdennym foam seal or seal the envelope with the production design cover, characterized in that the holding shell with foam at an elevated temperature and cooling is carried out at a gauge pressure of a gaseous environment surrounding the heated shell.



 

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