RU2767376C1 - Dustproof test chamber - Google Patents

Abstract

FIELD: test equipment.

SUBSTANCE: invention relates to test equipment in machine building and can be used to test electrical, electronic and radio equipment for dust resistance. Dustproof test chamber comprises a frame including a support, base 6, post 8 and platform 15. Sealed cabinet is installed on the support. Sealed cabinet is connected on one side by a pressure air duct 13 to fan 7, and on the other side it is connected by means of a discharge air duct 11 to an inlet hole of a dust collecting unit 10. On the front part of the sealed cabinet there is a door for installation of the tested article into the chamber and loading of dust-forming material (powder). Door has rotary handles with a locking cam, and on the sealed cabinet there are hinged screws for closing the door. Door has a glazed opening for observing the test article. Ceiling 16 in sealed cabinet is made with slotted hole for air flow outlet and has curved baffle 17 for air flow swirling, which contributes to more uniform distribution of dust suspension in volume of sealed cabinet. At the rear side of the sealed cabinet there is base 6, on which platform 15, fan 7 and post 8 are installed. On platform 15 there is a dust collection unit 10, in which the outlet hole is connected to the suction hole of fan 7 by means of air duct 9, and the hole for outlet of the filtered dust of the said dust collecting unit 10 is connected by the ejection branch pipe 12 to the pressure air duct 13. Post 8 is a support for air duct 9. Control and measuring equipment consists of thermal anemometer 14, fixed on the wall of the pressure air duct 13, chamber control panel, resistance thermal converter mounted on the side wall inside the sealed cabinet and the dust mass concentration analyzer (not shown) mounted in the sealed cabinet on the bracket next to the tested article. Air duct 9 directs the flow of cleaned air from dust collector 10 into the suction hole of fan 7, looping the air circuit of the chamber. Diameter of suction hole of fan 7 is more than diameter of air duct 9. Annular gap allows the fan, if necessary, to additionally suck in clean air from the surrounding space, ensuring normal operation of the fan and compensating for losses and fluctuations of the air flow in the circuit.

EFFECT: implementation of a closed air circulation system with dust-laden air flow cleaning before its supply to the fan, which significantly reduces the abrasive wear of its elements, as well as to minimize losses of dust-forming mixture during testing due to supply of filtered dust into pressure air duct.

1 cl, 4 dwg

Description

The claimed invention relates to the field of test equipment in mechanical engineering and can be used to test electrical, electronic and radio equipment for dust resistance.

From the prior art (RF patent for the invention RU 2403393, application No. 2008138014/03 dated September 25, 2008, published on November 10, 2010, Bull. No. 31), a design of a device for testing devices and elements of systems for air-gas and dust control of a mine atmosphere is known, including a test a chamber, a dust supply system, a system for creating a given air humidity and maintaining a temperature, a device for determining the degree of dust concentration and a measuring station, including a thermometer, flow meter, anemometer, pressure gauge installed in series, characterized in that, in order to establish reliable values of controlled parameters, the device equipped with a gas inlet system, and the test chamber is made of a toroidal shape and is a sealed closed air duct, made in an explosion-proof design, inside which the tested devices and elements of air-gas and dust control systems are located, and a fan that regulates the speed of the air jet flow in the test chamber, while the measuring station is additionally equipped with a gas analyzer, a Pitot full pressure tube, a psychrometer and an aspirator, each of the sensors of the measuring station is installed inside the test chamber through the corresponding input devices made in explosion-proof design.

The disadvantage of the design of this device is the absence of a system for cleaning the air flow passing through the fan, as a result of which abrasive wear of the fan parts occurs, and thereby reduces its service life.

Also from the prior art (author's certificate for the invention SU 894455, application No. Pr. the cross section of which is made variable, the means for creating a dusty air flow, the product holder, the holder drive, the fan, the blowing air duct connected to the air duct of the housing, the suction air duct connected to the bottom of the housing and the heating element placed in the air duct, while the housing is covered by an air duct with louvres and hermetically closed with a cover, and the drive shaft is connected to the holder.

The disadvantage of the device is the absence of a system for cleaning the air flow passing through the fan, as a result of which abrasive wear of the fan parts occurs, and thereby reduces its service life.

In addition, from the prior art (GOST 14254-96 "Degrees of protection provided by shells"), a device is known for testing protection against dust (shown in Fig. 2, p. 23), consisting of a housing in which the test sample is placed, a circulating pump (fan), dust filter, safety net, air flow meter, control and measuring equipment, including an air flow meter and a pressure gauge, the housing is connected by a supply air duct to a fan, the housing is also connected by an exhaust air duct to a dust-collecting unit, a window is placed on the housing to observe the object under test with glass. The presented scheme of the device is chosen as a prototype.

The device shown in the figure has a closed circuit, through which dust-polluted air circulates, and the dust in the circulating air flow, passing through the fan, exposes the fan parts to abrasive wear, reducing its service life. This is a significant disadvantage.

The technical result achieved from the claimed technical solution consists in the implementation of a closed air circulation system with cleaning of the dusty air flow before it is supplied to the fan, which can significantly reduce the abrasive wear of its elements, as well as minimize the loss of the dust-forming mixture during testing due to the supply of filtered dust into the intake duct.

The specified technical result is achieved due to the fact that the claimed chamber for dust tightness testing, containing a frame, including a stand, a base and a rack with a platform placed on it, a sealed cabinet mounted on a stand, connected on one side by a blowing duct to a fan, and on the other hand with an exhaust air duct, control and measuring equipment, additionally contains a ceiling in a sealed cabinet, made with a slotted hole for air flow outlet and having a curved baffle for swirling the air flow, a dust-collecting unit located on the site, the inlet of which is connected by an exhaust air duct to a sealed cabinet and an outlet the opening of which is connected to the suction opening of the fan by an air duct installed on the rack, and the opening for the exit of the filtered dust of the mentioned dust collecting unit is connected to the discharge air duct by an ejection pipe located concentrically on to the blowing air duct, while the connection of the fan intake opening and the air duct is made with an annular gap, and the control and measuring equipment consists of a hot-wire anemometer fixed on the wall of the blowing air duct, a resistance thermal converter installed on the side wall inside the sealed cabinet and a dust mass concentration analyzer mounted in a sealed cabinet on a bracket next to the product under test.

The essence of the claimed invention is illustrated by drawings:

Fig. 1 Dust test chamber (right view);

Fig. 2 Dust test chamber (front view);

Fig. 3 Scheme of the movement of air flows.

Fig. 4 Connection of the suction inlet of the fan with the air duct of the chamber (section A-A).

The chamber for dust tightness testing contains a frame, including a stand 3, a base 6, a rack 8 and a platform 15. A sealed cabinet 1 is installed on the stand 3. outlet air duct 11 with the inlet of the dust-collecting unit 10. On the front part of the hermetic cabinet 1 there is a door 2 for installing the tested product 5 into the chamber and loading the dust-forming material (powder). Door 2 has rotary handles with a locking cam, and hermetic cabinet 1 has hinged screws for tightening door 2. Door 2 has a glazed opening for observing the product under test 5. Ceiling 16 in hermetic cabinet 1 is made with a slotted hole for air flow and has a curved baffle 17 for swirling the air flow, which contributes to a more uniform distribution of dust suspension in the volume of the hermetic cabinet 1. On the back side of the hermetic cabinet 1 there is a base 6, on which a platform 15, a fan 7 and a stand 8 are installed. A dust-collecting unit is placed on the platform 15 10, in which the outlet is connected to the suction hole of the fan 7 with the help of an air duct 9, and the hole for the filtered dust outlet of the mentioned dust collecting unit 10 is connected by an ejection pipe 12 to the discharge air duct 13. The rack 8 is a support for the air duct 9. The control and measuring equipment consists of thermal anemometer 14, fixed on the wall of the supply air duct 13, the control panel of the chamber (not shown), the resistance temperature converter 4, mounted on the side wall inside the sealed cabinet 1, and the dust mass concentration analyzer (not shown), mounted in the sealed cabinet on a bracket next to the product under test.

The duct 9 directs the flow of purified air from the dust collector 10 to the suction inlet of the fan 7, looping the air circuit of the chamber. The diameter of the suction opening of the fan 7 is larger than the diameter of the air duct 9. Thus, the annular gap (Fig. 4) allows the fan, if necessary, to additionally suck in clean air from the surrounding space, ensuring the normal operation of the fan and compensating for losses and fluctuations in the air flow in the circuit.

The operation of the dust tightness test chamber is to periodically create dust inside the sealed cabinet 1 for a predetermined test time. The operation of the camera is carried out in a semi-automatic mode in accordance with the electrical circuit of the camera and the software. In a sealed cabinet 1, the test product 5 is installed on the bracket and a dust-forming material (powder) is placed.

During the tests, with a certain periodicity, the dust-forming material is perturbed by an air jet at a given speed. Air is blown into the hermetic cabinet 1 by a fan 7 through the air supply duct 13. The dust-forming material is located at the bottom of the hermetic cabinet 1, and during operation, the air flow picks up dust-forming material particles, creating dustiness. The air flow entering the curved baffle 17 of the ceiling 16 swirls, which contributes to a more uniform distribution of dust suspension in the volume of the sealed cabinet 1. Further, dusty air from the sealed cabinet 1 through a slot in the ceiling 16 enters through the exhaust duct 11 into the dust collecting unit 10, in which due to centrifugal forces, dust particles are separated from the polluted air and settled in the lower part of the dust collecting unit 10. The ejection pipe 12 connecting the filtered dust outlet of the dust collecting unit 10 with the blowing air duct 13 is located in the direction of the air flow and concentric to the air duct 13. Dust particles from the dust collecting unit 10 are entrained by the air flow from the fan 7 through the ejection pipe 12 due to the effect of ejection into the blowing air duct 13 and, thus, are returned back to the sealed cabinet 1. This system minimizes the loss of dust-forming mixture si during the test. The purified air from the outlet of the dust-collecting unit 10 is supplied through the air duct 9 to the suction inlet of the fan 7. Thus, a closed air circulation system is implemented in the chamber with dusty flow cleaning before air is supplied to the fan, which can significantly reduce the abrasive wear of its elements.

The diagram of the air flow in the chamber is shown in Fig. 3.

The air flow rate is measured by hot-wire anemometer 14 and is adjusted on the camera control panel (not shown). The air temperature in the chamber is measured by a resistance thermocouple 4, the dust concentration in the sealed cabinet 1 during the test is measured by a dust mass concentration analyzer (not shown).

At the end of the test, the test object 5 is disassembled and the amount of dust that has got inside is visually estimated.

Distinguishing features from the prototype: the prototype has a closed circuit, through which air polluted with dust circulates, and the dust in the circulating air flow, passing through the fan, exposes the fan parts to abrasive wear, reducing its service life. In the proposed design of the dust-tightness test chamber, an additional air purification circuit is added, including a dust-collecting unit installed on the site and connected by appropriate air ducts to the chamber assemblies, as a result of which the fan receives purified air that has passed through the dust-collecting unit. Thus, the abrasive wear of the fan parts is significantly reduced and its service life is increased, while the dust filtered by the dust-collecting unit enters the blowing air duct, which eliminates its (dust) losses during testing, thereby reducing the labor intensity associated with the addition of dust-forming material in chamber, and there is no need to create complex devices for automatic supply of dust-forming material.

At JSC NPK Uralvagonzavod, the claimed invention is used in the mechanical assembly shop to test electrical, electronic and radio equipment for dust tightness and has confirmed its technical and economic efficiency.

Claims (1)

Chamber for dust resistance testing, containing a frame, including a stand, a base and a rack with a platform placed on it, a hermetic cabinet installed on the stand, connected on one side with a blower air duct to a fan, and on the other hand with an exhaust air duct, control and measuring equipment, different the fact that it additionally contains a ceiling in a sealed cabinet, made with a slotted hole for air flow outlet and having a curved baffle for swirling the air flow, a dust-collecting unit located on the site, the inlet of which is connected by an exhaust air duct to a sealed cabinet, the outlet hole is connected to the suction hole of the fan an air duct installed on the rack, and the hole for the filtered dust outlet of the mentioned dust collecting unit is connected to the injection air duct by an ejection pipe located concentrically to the injection air duct, while the connection of the suction outlet The fan and air duct openings are made with an annular gap, and the control and measuring equipment consists of a hot-wire anemometer mounted on the wall of the supply air duct, a resistance thermal converter installed on the side wall inside the sealed cabinet, and a dust mass concentration analyzer mounted in the sealed cabinet on a bracket next to the product under test .

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