RU180577U1 - VALVE FOR DEPRESSION OF ELECTRONIC INSTRUMENTS - Google Patents

Abstract

The utility model relates to electronic and space technology and can be used to depressurize the internal volumes of devices, in particular microwave equipment. The objective of the utility model is to improve the device for depressurizing electronic devices, including in space technology, and to improve its operational characteristics. the result is the reliability of the depressurization of the electronic device at a pressure drop in the range from 0.3 atm (~ 0.03 MPa) to 0.7 atm (~ 0.07 MPa) in the temperature range from -60 ° C to + 100 ° C without The use of control signals. The technical result is achieved by the fact that in the claimed device comprising a housing, a cover, a destructible membrane and a membrane destruction mechanism, there is additionally a mesh located in front of the membrane, a destruction mechanism located behind the membrane and made in the form of a knife, the mesh and knife fixed, while the membrane is made of metal foil with a thickness of not more than 0.1 mm from a plastic material with low specific strength.

Description

The utility model relates to electronic and space technology and can be used to depressurize the internal volumes of devices, in particular microwave equipment.

The valve must reliably operate at a pressure drop in the range from 0.3 atm (~ 0.03 MPa) to 0.7 atm (~ 0.07 MPa) in the temperature range from -60 ° C to + 100 ° C without using control signals and have small overall dimensions.

Known devices for active depressurization, containing a membrane that overlaps the sealed volume, and a controlled mechanism for the destruction of the membrane, made in the form of a knife, which is driven by the pressure of gases generated when the pyrotechnic charge is triggered [Veselov A.I., Meshman L.M. Automatic fire and explosion protection of chemical and petrochemical enterprises. - M.: Chemistry, 1975 - p. 241]. The design drawback of such devices is the presence of a remotely controlled destruction mechanism, in addition, such devices cannot be used in electronic equipment due to the presence of a pyrotechnic charge.

A device for depressurizing the internal volumes of radio equipment [ed. St. USSR No. 270852], containing a membrane and a remotely controlled membrane destruction mechanism, consisting of a needle equipped with shoulders, on which a spring and a wire holder are connected, connected through a key to a current source.

The disadvantages of this design are the use of external electrical control signals, the difficulty of calibrating the spring for use in a given narrow range of pressure drops, the risk of accidental operation during vibration loads.

Known membrane safety devices used on gaseous media [Rules for the development, manufacture and use of membrane safety devices (PB 03-583-03)]. For example, a membrane safety device (MPU) with a bursting disc. A device with a bursting disc, used in the absence of backpressure oscillations from the side of the discharge system, contains a flat membrane that works to burst under pressure acting on its surface [ПБ 03-583-03, Appendix 2, Fig. 1a].

In such devices, the destruction of the membrane occurs without the use of a controlled mechanism of destruction, as a result of pressure changes on one side of the membrane (from the discharge system).

The main disadvantage of this design is that it is designed to change the pressure inside the device at a constant pressure from the outside (from the discharge system), while the working pressure range is at least 0.1 MPa, which does not allow the use of such devices for depressurization of electronic devices.

The closest technical solution, selected as a prototype, is a device with a "popping" membrane, working for loss of stability, used in the absence of fluctuations in back pressure from the discharge system. Dome-shaped membrane partition working for buckling (cotton) under pressure acting on a convex surface. Losing stability, the membrane is cut on knife blades or torn along a previously weakened section.

In such devices, membrane destruction also occurs without the use of a controlled destruction mechanism as a result of pressure changes on one side of the membrane (from the discharge system). Such devices are simple in design and reliable.

The disadvantages of a "popping" membrane is that the response pressure is determined not by the strength of the material, but by the stability of its spherical dome. Thus, an accurate calculation of the response pressure to ensure reliable depressurization of the device in a narrow range of pressure drops in the device for depressurization of electronic equipment is not possible.

The objective of the utility model is to improve the device for depressurization of electronic devices, including in space technology, and to improve its operational characteristics.

The technical result is the reliability of the depressurization of the electronic device at a pressure differential "inside / outside" in the range from 0.3 atm (~ 0.03 MPa) to 0.7 atm (~ 0.07 MPa) in the temperature range from -60 ° C to + 100 ° C without the use of control signals.

The technical result is achieved by the fact that in the inventive valve, comprising a housing, a destructible membrane and a membrane destruction mechanism, there is additionally a mesh located in front of the membrane, a destruction mechanism located behind the membrane and made in the form of a knife, the mesh and knife being stationary, while the membrane is made from metal foil with a thickness of not more than 0.1 mm. The membrane material must simultaneously satisfy a number of requirements, in particular, to preserve physical properties over a wide range of temperatures, manufacturability, and corrosion resistance.

The valve body is used for mounting all parts and attaching the valve to a device that requires depressurization.

The grid is located in front of the membrane, on the side of the device requiring depressurization, and is a plate with a thickness of at least 1 mm with perforation with the displacement of the holes from the central region, and the total area of perforated holes in the grid is at least 2 times the area of the channel connecting to the device.

Due to the perforation in the grid, an easy passage of gas filling the sealed device to the membrane is provided. Thanks to the special design and displacement of the holes from the central region, a labyrinth protection of the components of the depressurized device from direct penetration of external flows of charged particles is created.

The grid also serves as a limiter for moving the membrane in the non-working direction, the gap from the grid to the membrane is in the range of 0.6-0.8 mm.

A knife in the form of a corner, located behind the membrane, is mounted in the lid with a predetermined gap (in the range of 0.3-0.5 mm, the gap depends on the material and thickness of the membrane) to the membrane and serves to guarantee the opening of the membrane. The blade of the knife is offset relative to the axis of symmetry of the base of the knife and the center of the membrane, the knife is made with a reverse bevel at an angle lying in the range from 30 ° to 60 °, which ensures a guaranteed opening of the membrane without sticking on the knife.

The mesh and knife are stationary, which increases the reliability of the device and eliminates the accidental operation of the device during storage and when passing vibration tests.

The membrane is made of metal foil with a thickness of not more than 0.1 mm from a plastic material with low specific strength.

The design of the utility model is illustrated in the drawing. In FIG. 1 shows a device in section.

The valve for depressurization of electronic devices contains a housing (1) in which a grid (2), a metal membrane (3), a knife (4), a cover (5) are placed.

In FIG. Figure 2 shows a graph of the rate of air pressure drop in a thin-walled shell of volume V with a small hole of area S under external vacuum.

The principle of operation of the valve is as follows. The valve body (1) is connected to a sealed device. The area to the left of the membrane (3) communicates with the interior of the sealed device, the area to the right through the cover (5) with the external environment. If the external pressure is higher than the internal one, the membrane abuts against the grid (2) and remains intact. If the external pressure is lower than the internal one, the membrane begins to bend towards the reduced pressure and, reaching the cutting edge of the knife (4), breaks through, which ensures the depressurization of the attached electronic device.

The valve body and knife are made of brass, the cover and mesh are made of aluminum alloy D16. All parts are nickel plated. The mesh is mounted in the valve body, and the knife is mounted in the lid using POS61 solder. The membrane with the body and the cover with the body are mounted vacuum-tight solder POIN-50. When connecting the cover and the body, the membrane is automatically located at a distance of 0.6-0.8 mm from the grid. For storage of the device, a stopper with a gasket is screwed into the valve cover; for this, a screw hole for the stopper is provided in the cover with a special recess for sealing. Closed volumes of gas appear on both sides of the membrane, which behave identically at temperature differences and do not unload the membrane unnecessarily. As a sealant, vacuum rubber 1 mm thick is used.

The membrane material has a number of requirements. Firstly, the membrane material must withstand operational temperature differences in the range from -60 ° C to + 100 ° C. Secondly, due to the small working differential pressure, the rupture force of the membrane should be small, that is, the membrane material should have a low specific strength. Thirdly, the membrane material must be technologically advanced in processing, provide the possibility of vacuum-tight connection with other parts, possess the necessary strength and corrosion resistance, be gas-tight, and ensure the possibility of manufacturing a valve that does not significantly change the overall dimensions of the sealed device. Foil samples of pure indium, pure lead, tin-lead alloys (for example, POS61) showed themselves most well.

The rate of depressurization of the device when the valve is triggered depends on the size of the membrane breakout hole and the volume of the device.

To assess the adequacy of the size of the punctures, the Higgins equation was used, which describes the rate of air pressure drop in a thin-walled shell of volume V with a small hole of area S in an external vacuum:

P = Ro⋅ekhr (-S / V⋅t⋅200).

When the volume of the device is 0.5-0.6 l, even a hole with an area of 0.1 mm ^{2 is} enough to drop pressure by 3 orders of magnitude over a period of about 5 minutes (Fig. 2).

The valve design is universal, and the size and choice of membrane material depends on the volume of the depressurized device.

Thus, the use of the valve of the proposed design will improve the reliability of the depressurization of electronic devices in space technology without the use of control signals.

Claims (5)

1. Valve for depressurization of electronic devices, comprising a housing, a cover, a destructible membrane and a membrane destruction mechanism, characterized in that on the electronic device side it is provided with a mesh located in front of the membrane, the destruction mechanism located behind the membrane is made in the form of a knife, the mesh being and the knife is stationary, while the membrane is a metal foil with a thickness of not more than 0.1 mm, made of plastic material with low specific strength. 2. The valve according to claim 1, characterized in that the grid is made in the form of a plate with a thickness of at least 1 mm with perforation of the holes, the perforation being made with an offset from the central region, and the total area of the perforated holes in the grid is at least 2 times the area channel connection with the device. 3. The valve according to claim 1, characterized in that the gap from the mesh to the membrane is in the range of 0.5-0.8 mm. 4. The valve according to claim 1, characterized in that the knife is made in the form of a corner, and the blade of the knife is offset relative to the axis of symmetry of the base of the knife and the center of the membrane, the knife is made with a reverse bevel at an angle lying in the range from 30 ° to 60 °. 5. The valve according to claim 1, characterized in that the knife is mounted in the lid with a gap to the membrane of 0.3-0.5 mm.

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