CN105833446B

CN105833446B - Ultrasonic fire extinguisher

Info

Publication number: CN105833446B
Application number: CN201610282224.5A
Authority: CN
Inventors: 魏衍举; 杨亚晶; 刘圣华; 李东华
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2016-04-29
Filing date: 2016-04-29
Publication date: 2021-03-16
Anticipated expiration: 2036-04-29
Also published as: CN105833446A

Abstract

An ultrasonic fire extinguisher comprises an energy converter with a wiring port, which is arranged on a base cylinder, the energy converter is connected with an external ultrasonic signal generator through the wiring port, an amplitude transformer with a transmitting cone cylinder is arranged at the transmitting end of the energy converter in the base cylinder, an energy-gathering cover is arranged on the transmitting cone cylinder at the tail end of the base cylinder and positioned at the rear end of the amplitude transformer, and a reflecting disc is also arranged at the outer side of the base cylinder; the invention adopts the cone-shaped transmitting end, the inner surface of the cone-shaped transmitting end not only generates ultrasonic waves, but also can reflect the ultrasonic waves transmitted oppositely, and the transmitting and reflecting actions are integrated; the energy-gathering cover reflects the ultrasonic waves emitted by the lower half part of the emission cone towards the front, so that all the forward emitted sound waves are collected. The reflecting cover reflects and forwards transmits the ultrasonic waves which are emitted backwards and outwards by the emission cone. Therefore, all the ultrasonic energy emitted by each surface of the emitting end is concentrated to the front for parallel emission, and the effective acoustic energy and the effective acting area are improved by 8 times compared with the effective acoustic energy and the effective acting area which are transmitted forwards without the energy-gathering cover and the reflecting plate.

Description

Ultrasonic fire extinguisher

Technical Field

The invention belongs to the field of fire-fighting equipment, and particularly relates to an ultrasonic fire extinguisher.

Background

The sound is transmitted in the air in the form of longitudinal waves, so that the density degree of the medium is changed, the air is in a compressed state and a sparse state, the original atmospheric static pressure is increased or reduced, and the sound pressure is generated. The sound pressure value in the compressed state is a positive value, and the sound pressure in the sparse state is a negative value. This propagation process is only a transfer of energy, and no mass transfer occurs, and the air molecules cannot be displaced directly, but vibrate near the equilibrium position. Thus, the sound has three effects on the combustion phenomenon: (1) the longitudinal vibration of gas molecules plays a role in tearing the flame surface in a gas state, when the amplitude is small, the heat and mass transfer process near the flame surface can be enhanced, the propagation of combustion is promoted, and when the amplitude is large, the flame can be vibrated out; (2) the uniformly distributed air molecules can present density distribution under the influence of sound waves, so that the oxygen concentration in the flame area is uneven. In the low density region, the flame will self-extinguish due to the lack of combustion conditions; (3) the generated sound pressure continuously slaps the combustion flame or solid surface at sonic velocity, producing cooling and whipping effects. Under the simultaneous action of the three effects, the sound wave can extinguish the flame and the blind fire simultaneously. The ultrasonic fire extinguisher of the invention utilizes the high-power ultrasonic transducer to directionally emit high-decibel sound waves to directly irradiate an ignition area, and quickly extinguish flames and hidden fires.

Ultrasonic fire extinguishing is a novel fire extinguishing technology. The ultrasonic wave has the characteristics of good directivity, strong penetrating power, easy acquisition of more concentrated sound energy and the like. The ultrasonic wave is widely applied to the fields of ultrasonic inspection, ultrasonic treatment, molecular acoustic basic research and the like, and research information on ultrasonic fire extinguishing is rarely reported. The united states military organization DAPRA developed a sonic fire-extinguishing product in 2008, whose sonic parameters and subsequent applications were unknown. In 2015, the Viet Tran and Seth Robertson of george meisen university in usa invented a speaker fire extinguisher, the device consisted of a large-size speaker and a portable terminal, and the sound wave frequency emitted was a low-frequency wave between 30-60 Hz. At present, the invention only can put out a few small fire species in the prototype stage, and a plurality of technical problems need to be overcome. In 2008, fire fighting technology and product information are reported to Japan as an ultrasonic fire extinguishing training machine, and detailed information thereof is not reported. In 2007, Wujian was theoretically discussing the feasibility of ultrasonic fire extinguishing. In 2011, Liu Yi Min and the like obtain a patent authorization (CN1012294188.2011.05) of an ultrasonic atomization fire extinguisher, the principle of the fire extinguisher is that water is firstly atomized by using ultrasonic waves, then the fire extinguisher is put out by using water vapor, the fire extinguishing medium is water, and the ultrasonic waves play a role in strengthening water to extinguish fire.

The ultrasonic fire extinguishing technology is not practically applied, and has a great relationship with the ultrasonic energy-gathering failure of the ultrasonic wave emitted by the ultrasonic vibrator amplitude transformer head. The ultrasonic vibrator consists of two parts, namely a transducer and a horn. The function of the amplitude transformer is to amplify the amplitude of the high-frequency longitudinal vibration generated by the transducer and to transmit the vibration to the air. For a T-head horn, the emitted ultrasonic waves have a scattering angle of about 15 °, so that theoretically, the ultrasonic surface energy density is reduced to 7.5% of the original value 10 times the diameter of the T-shaped emitting end surface in front of the T-shaped emitting horn. This results in a rapid attenuation of the ultrasonic energy. If the fire extinguishing agent is used for extinguishing fire, the effective action distance is generally not more than 1m, and the fire extinguishing agent has no practical value. For the concave emitting end, the local vibration of the emitting end is the vibration in the thickness direction, so the concave surface is similar to a concave mirror to condense light, and the concave emitting end also has the function of condensing sound, but the effective acting distance does not exceed the focal length. Considering that the diameter of the transmitting end surface of the amplitude transformer is generally in the order of several centimeters, the effective holding distance of the amplitude transformer is not more than tens of centimeters farthest, and the amplitude transformer has limitation on being used for fire extinguishing. For the conical surface transmitting end, most of sound energy is directly transmitted towards the vertical direction of the conical surface without being transmitted towards the right front direction, so that the energy obtained in front of the transmitting end is limited, and the conical surface transmitting end cannot be used for long-distance fire extinguishment.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides the ultrasonic fire extinguishing device which has the advantages of large energy, high energy density, large action area, good sound directivity, slow sound attenuation and long action distance.

In order to achieve the purpose, the invention adopts the technical scheme that: the ultrasonic transducer comprises an energy converter which is arranged on a base cylinder and provided with a wiring port, wherein the energy converter is connected with an external ultrasonic signal generator through the wiring port, an amplitude transformer with an emission cone cylinder is arranged at the emission end of the energy converter in the base cylinder, an energy gathering cover is arranged on the emission cone cylinder at the tail end of the base cylinder and positioned at the rear end of the amplitude transformer, and a reflecting disc is further arranged on the outer side of the base cylinder.

The transducer adopts a 300W, 20kHz piezoelectric ceramic ultrasonic transducer to generate 200dB ultrasonic waves.

The amplitude transformer with the transmitting cone is an ultrasonic transmitting end, the transmitting cone at the tail end of the amplitude transformer adopts a 60-degree hollow frustum structure, and the inner frustum and the outer frustum form a cone structure with a top surface and a bottom surface.

The energy-gathering cover is tightly connected with the launching cone of the amplitude transformer and has a 60-degree cone structure, and the length of the cone edge of the energy-gathering cover is equal to the diameter l of the bottom surface of the amplitude transformer cone.

The reflecting disc is of a 120-degree conical surface structure, and the top of the reflecting disc is cylindrical and is sleeved on the base cylinder and can move back and forth along the base cylinder.

The transducer outer side is also provided with a transducer cover which protects the transducer and facilitates holding by people or installation on other devices.

The invention adopts the cone-shaped transmitting end, the inner surface of the cone-shaped transmitting end not only generates ultrasonic waves, but also can reflect the ultrasonic waves transmitted oppositely, and the transmitting and reflecting actions are integrated; the energy-gathering cover reflects the ultrasonic waves emitted by the lower half part of the emission cone towards the front, so that all the forward emitted sound waves are collected. The reflecting disc reflects and transmits the ultrasonic waves which are emitted backwards and outwards by the emission cone forwards. Therefore, all the ultrasonic energy emitted by each surface of the emitting end is concentrated to the front for parallel emission, and the effective acoustic energy and the effective acting area are improved by 8 times compared with the effective acoustic energy and the effective acting area which are transmitted forwards without the energy-gathering cover and the reflecting plate.

In addition, the sound waves emitted from the inner surface of the emitting end have the same phase because the propagation distance is the same regardless of whether the sound waves are reflected by the inner surface. The back-emitted ultrasound is similarly in phase. The propagation distance of the reflected sound wave is adjusted by changing the position of the reflecting disc, the sound waves emitted and reflected in the forward direction and the backward direction can be adjusted to the same phase, and therefore the sound waves dispersed in the direction are adjusted to a beam of parallel plane waves. The effective action distance of the ultrasound is greatly increased.

Compared with the traditional fire extinguisher, the sound wave fire extinguisher has the following advantages: the reaction is rapid, the fire can be extinguished after being triggered, and the fire development can be rapidly controlled; secondly, the penetrating power is strong, the sound wave can directly reach the lower part of the multilayer fiber combustible to directly extinguish the blind fire; the fire extinguishing process is clean, and no secondary dust pollution is generated; fourthly, consumables such as fire extinguishing agent and the like are not needed, and potential safety hazards of explosion of the fire extinguisher tank body do not exist; the volume is small, the weight is light, the installation is convenient, the operation is flexible, the maintenance is convenient, and the cost is low; and after the automatic fire extinguishing system is formed, the remote control of the fire extinguishing process can be realized, and the like. Therefore, the ultrasonic fire extinguishing device is used for extinguishing fire in limited closed spaces such as aircraft cabins, space stations and the like, can greatly improve the flight safety coefficient, and has very wide application prospect.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention.

Fig. 2 is a schematic diagram of the present invention.

Detailed Description

The present invention is described in further detail below with reference to the attached drawings.

Referring to fig. 1, the invention includes a transducer 7 with a wiring port 1 installed on a base cylinder 5, the transducer 7 is connected with an external ultrasonic signal generator through the wiring port 1, the outer side of the transducer 7 is also installed with a transducer cover 2 for protecting the transducer and facilitating holding by people, or facilitating installation on other devices, an amplitude transformer 6 with a transmitting cone is installed at the transmitting end of the transducer 7 in the base cylinder 5, the amplitude transformer 6 with the transmitting cone is an ultrasonic transmitting end, the transmitting cone at the tail end adopts a 60-degree hollow cone frustum structure, the inner cone frustum and the outer cone frustum form a cone cylinder structure with top surface and no bottom surface, an energy-collecting cover 4 is installed on the transmitting cone at the tail end of the base cylinder 5 and at the rear end of the amplitude transformer 6, the energy-collecting cover 4 is next to the transmitting cone cylinder of the amplitude transformer 6, the cone cylinder structure is a 60-degree cone cylinder structure, the bottom surface diameter l of the cone cylinder of the cone amplitude transformer 6 is equal, the outer side of the base cylinder 5 is also provided with a reflecting disc 3 which is in a 120-degree conical surface structure, and the top of the reflecting disc is cylindrical and is sleeved on the base cylinder 5 and can move back and forth along the base cylinder 5.

The transducer of the invention adopts a 300W, 20kHz piezoelectric ceramic ultrasonic transducer to generate 200dB ultrasonic waves.

The generation of ultrasonic waves of the present invention. High-frequency high-energy sinusoidal signals generated by an ultrasonic signal generator (external equipment) are transmitted to the transducer 7 through the wiring port 1, and piezoelectric ceramics of the transducer 7 generate periodic deformation under the action of sinusoidal voltage, so that high-frequency vibration is generated. After being amplified by the amplitude transformer 6, the vibration amplitude is transmitted to an air medium through the transmitting end to cause air vibration and spread outwards, namely, ultrasonic waves are generated.

Direct and reflected ultrasonic waves. Because the vibration transmitted by the emitting end of the amplitude transformer 6 is along the normal direction of the emitting surface, and the emitting end is in a flat-top conical cylinder shape, the ultrasonic wave generated by the flat-top vibration is directly transmitted forwards; ultrasonic waves generated by vibration of the inner conical surface of the ultrasonic wave transmitting device are transmitted outwards in a normal direction, and when the ultrasonic waves are transmitted to the opposite inner conical surface formed by the transmitting end and the energy-gathering cover together, reflection is generated, and the rear direction of the reflection is forward. As shown in fig. 2, the sound flow emitted from all front vibration surfaces is rectified to be transmitted forward by the self-reflection of the conical surface.

And (4) collecting the back ultrasonic waves. The back of the transmitting end of the cone also transmits the ultrasonic waves outwards, but the ultrasonic waves are generally ignored. The cone reflecting disc designed by the invention can conveniently and integrally transmit the ultrasonic wave emitted from the back of the emitting end forward, and effectively collect the other half of the emitted energy as shown in figure 2. The propagation distance of the reflected sound wave can be adjusted by changing the position of the reflecting disc, so that the phase of the reflected sound wave is in phase with the phase of the forward transmitted sound wave on the inner surface of the transmitting end. Thus, the acoustic wave emitted by the emitting end in all directions is adjusted into a beam of parallel acoustic wave which has the same phase and is emitted in the forward direction.

The function of the transducer cover. The transducer cover can be made into any shape on the premise of ensuring the transducer to be covered. Therefore, there is a large space for expanding the design according to the usage. For example, the extension rod can be made into a long cylinder shape to be convenient to hold by hands, and connecting parts such as bolts can be additionally arranged on other extension equipment, such as extension rods, automatic searching actuators and the like.

According to the cone-shaped transmitting end, the inner surface integrates transmitting and reflecting functions, and the outer surface transmits sound waves and is easy to collect; the energy-gathering cover is additionally arranged on the front barrel of the transmitting end, so that 75% of energy dissipated by the inner transmitting surface can be collected; the reflecting disc can collect the other 50% of energy emitted by the emitting end; the transmitting end, the energy-gathering cover and the reflecting disc jointly form a beam of forward high-energy ultrasonic waves which are propagated in the same phase, so that the effective propagation distance is increased to 8 times that of the ultrasonic waves without the energy-gathering cover and the reflecting disc.

Claims

1. An ultrasonic fire extinguisher, which is characterized in that: the ultrasonic transducer comprises a transducer (7) which is arranged on a base barrel (5) and provided with a wiring port (1), wherein the transducer (7) is connected with an external ultrasonic signal generator through the wiring port (1), an amplitude transformer (6) with a transmitting cone is arranged at a transmitting end of the transducer (7) in the base barrel (5), an energy gathering cover (4) is arranged on the transmitting cone which is arranged at the rear end of the amplitude transformer (6) at the tail end of the base barrel (5), a reflecting disc (3) is further arranged at the outer side of the base barrel (5), the transducer (7) adopts a 300W and 20kHz piezoelectric ceramic ultrasonic transducer to generate 200dB ultrasonic waves, the amplitude transformer (6) with the transmitting cone is an ultrasonic transmitting end, the transmitting cone at the tail end adopts a 60-degree hollow frustum structure, and the inner and outer cones form a cone structure with a top surface and without a bottom surface.

2. The ultrasonic fire extinguisher of claim 1, wherein: the energy-gathering cover (4) is connected with the launching cone of the amplitude transformer (6) and has a 60-degree cone structure, and the length of the cone edge of the energy-gathering cover is equal to the diameter l of the bottom surface of the cone of the amplitude transformer (6).

3. The ultrasonic fire extinguisher of claim 1, wherein: the reflecting disc (3) is of a 120-degree conical surface structure, the top of the reflecting disc is cylindrical, and the reflecting disc is sleeved on the base cylinder (5) and can move back and forth along the base cylinder (5).

4. The ultrasonic fire extinguisher of claim 1, wherein: the outer side of the transducer (7) is also provided with a transducer cover (2) which can protect the transducer and is convenient for people to hold, or is convenient for being arranged on other devices.