Abstract:
The present invention relates to a gas filtering-buffering device, which comprises at least one gas filtering unit; a gas inlet, the gas to be processed flows into the at least one gas filtering unit from the gas inlet; and a gas outlet, the gas processed by the at least one gas filtering unit is discharged out of the at least one gas filtering unit via the gas outlet, wherein the at least one gas filtering unit comprising: a gas buffering cavity for performing buffering function for the gas, and a gas filtering part for performing filtering function for the gas. In the present invention, it is not only provided with a gas filtering part which is able to filter the moisture and organic substance in the gas, but also provided with a gas buffering cavity, which integrate the filtering and buffering functions together. The buffering cavity may expand the capacity and stabilize the pressure of the gas, and balance the concentration, pressure and flow rate of the gas, it is advantageous to reduce the on-way pressure lost and partially pressure lost, decrease fluctuation of the flow current and the pressure thus, the detecting performance of the detector is improved.

Description:
The present application claims priority of Chinese patent application Serial No. 200610171614.1, filed Dec. 31, 2006, the content of which is hereby incorporated by reference in its entirety. 
     FIELD OF INVENTION 
     The present invention relates to a gas filtering device, more particularly, to an integrated device, which used in a trace detector for detecting explosives and drugs, to filtrate and buffer the migrated gas and reacted gas. 
     BACKGROUND OF INVENTION 
     In conventional arts, a filter used in a trace detector for detecting explosives and drugs only has effects in filtering water, organic substances and absorbable particles in the migrated gas and reacted gas. Filter medium is filled in the whole inner space of the filter. Due to the sucking action from the gas source, the migrated gas in the flow path of the detector passes through the filter before entering into the migrated pipe. Because of the on-way pressure lost and partially pressure lost of the gas flow caused by the filter, as well as the uncertainty of the arrangement of the particle filter medium and the effects of the inner structure of the filter, the flow current and the pressure of the passing gas is fluctuated. Thus, the detecting performance of the detector is affected and the detecting precision is decreased. 
     SUMMARY OF INVENTION 
     One object of the present invention is to overcome at least one aspect of the limitation and shortages existing in the arts. 
     Accordingly, one object of the present invention is to provide a gas filtering-buffering device, which is able to provide filtering function and buffering function to the gas to be processed, thus, the detection precision of a trace detector is improved. 
     According to one aspect of the present invention, there is provided a gas filtering-buffering device which comprises, at least one gas filtering unit; a gas inlet, the gas to be processed flows into the at least one gas filtering unit from the gas inlet; and a gas outlet, the gas processed by the at least one gas filtering unit is discharged out of the at least one gas filtering unit via the gas outlet, wherein the at least one gas filtering unit comprising: a gas buffering cavity for performing buffering function for the gas, and a gas filtering part for performing filtering function for the gas. 
     In one embodiment, the at least one gas filtering unit includes: a first gas filtering unit and a second gas filtering unit connected hermetically and in series, wherein the first gas filtering unit including a first gas buffering cavity and a first gas filtering part, and the second gas filtering unit including a second gas buffering cavity and a second gas filtering part. 
     Preferably, the first gas filtering unit and the second gas filtering unit are connected by a connection unit, the connection unit is provided with a flow passage through which the gas from the first gas filtering unit flows into the second gas filtering unit. 
     Furthermore, the first gas filtering unit, the connection unit and the second filtering unit may be configured to have a substantial U-shape. Alternatively, the connection unit may be integrated with the first gas filtering unit and the second filtering unit. 
     In a further embodiment, the first gas buffering cavity is provided at the upstream of the first gas filtering part in a gas flow direction; and the second gas buffering cavity is provided at the downstream of the second gas filtering part in the gas flow direction. 
     Preferably, the first gas filtering part has a moisture filter medium layer; and the second gas filtering part having an organic substance filter medium layer and an absorbing filter medium. 
     Preferably, the gas filtering-buffering device further comprises: a first porous filter medium baffle provided between the first gas buffering cavity and the moisture filter medium layer; and a second porous filter medium baffle provided between the second gas buffering cavity and said organic substance filter medium layer and absorbing filter medium layer. 
     Preferably, the gas filtering-buffering device further comprises: a first precise filtering layer provided between the gas inlet and the first gas buffering cavity; and a second precise filtering layer provided between the gas outlet and the first gas buffering cavity. 
     Preferably, the gas filtering-buffering device further comprises: a first precise filtering layer baffle provided between the first precise filtering layer and the first gas buffering cavity; and a second precise filtering layer baffle provided between the second precise filtering layer and the second buffering cavity. 
     Alternatively, the gas filtering-buffering device further comprises: a first adjusting member provided in the first gas buffering cavity for adjusting the precision of the moisture filter medium layer; and a second adjusting member provided in the second gas buffering cavity for adjusting the precision of the organic substance filter medium layer and the absorbing filter medium layer. 
     Alternatively, the gas filtering-buffering device further comprises: a third adjusting member provided in the first gas buffering cavity for adjusting the filtering precision of the first precise filtering layer; and a forth adjusting member provided in the second gas buffering cavity for adjusting the filtering precision of the second precise filtering layer. 
     Alternatively, the gas filtering-buffering device further comprises: a first draw bar penetrating through the first filtering unit and connecting the first gas filtering unit and the connection unit; and a second draw bar penetrating through the second filtering unit and connecting the second gas filtering unit and the connection unit. 
     Alternatively, the first adjusting member is a nut, which is engaged with a first threaded portion provided on the first draw bar and movable along with the first draw bar, so that the filtering precision of the moisture filter medium layer is adjusted by moving the first porous filter medium baffle; and the second adjusting member is a nut, which is engaged with a second threaded portion provided on the second draw bar and movable along with the second draw bar, so that the filtering precision of the organic substance filter medium layer and the absorbing filter medium layer are adjusted by moving the second porous filter medium baffle. 
     Alternatively, the third and forth adjusting member are nuts, which are engaged with third and forth threaded portions and movable along with the first and second draw bars, respectively, so that the filtering precision of the first and second precise filtering layers are adjusted by moving the first and second precise filtering layer baffle. 
     In one embodiment, the gas filtering-buffering device further comprises: a first opening and a second opening provided at the first and second gas buffering cavity; and a first cover member and a second cover member movably connected to and closed the first and second openings. Preferably, sealing members are respectively provided between the first and second openings and the first and second cover members. 
     In an embodiment, each of the first and second gas filtering units may have an integrated structure. 
     In an embodiment, each of the first and second gas filtering units includes a cartridge filter and a cartridge filter cover connected hermetically with each other, respectively; and each of the first and second gas buffering cavities is provided within the cartridge filter cover, respectively. 
     The advantage of at least one aspect of one embodiment and the positive effects are: 
     In the present invention, it is not only provided with a gas filtering part which is able to filter the moisture and organic substance in the gas, but also provided with a gas buffering cavity, which integrate the filtering and buffering functions together. The buffering cavity may expand the capacity and stabilize the pressure of the gas, and balance the concentration, pressure and flow rate of the gas. Also it is advantageous to reduce the on-way pressure lost and partially pressure lost, decrease fluctuation of the flow current and the pressure thus, the detecting performance of the detector is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is front view of the gas filtering-buffering device of the present invention; 
         FIG. 2  is top view of  FIG. 1 ; 
         FIG. 3  is section view of the gas filtering-buffering device of the present invention; 
         FIG. 4  is a cross-sectional view taken along with line A-A of  FIG. 3 ; and 
         FIG. 5  is a schematic view of the structure of the precise filtering layer baffle in the present invention. 
     
    
    
     In drawings, wherein: 
       1 . gas inlet;  2 . precise filtering layer;  3 . precise filtering layer baffle;  4 . inlet-gas buffering cavity;  5 . adjusting nut;  7 . porous filter medium baffle;  8 . first cartridge filter;  9 . moisture filter medium layer;  10 . central draw bar;  12 . built-in passage end plate;  13 . built-in passage;  15 . absorbing filter medium layer;  16 . organic substance filter medium layer;  17 . second cartridge filter;  20 . porous padding baffle;  21 . outgas buffering cavity;  23 . outlet precise filtering layer baffle;  24 . outlet precise filtering layer;  25  gas outlet;  26 . fixed distance sealing pressure plate;  28 . sealing ring;  29 . locking nut;  30 . sealing ring;  31 . rotary cover;  32 . mounting screw hole;  33 . first filter;  34 . second filter;  36 . first cartridge filter;  37  second cartridge cover. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described hereinafter in detail with reference to the attached drawings, wherein the like reference numerals refer to the like elements throughout the specification. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. 
     As shown in  FIGS. 1-4 , a gas filtering-buffering device comprises a first filter  33  which serves as the first filtering unit, and the second filter  34  which serves as the second filtering unit, the first filter  33  and the second filter  34  are connected hermetically with each other and in series. The first filter  33  is provided therein with an inlet-gas buffering cavity  4  as a first gas buffering cavity and an inlet-gas filtering part as a first gas filtering part, and the second filter  34  is provided therein with an outgas buffering cavity  21  as a second gas buffering cavity and an outgas filtering part as a second gas filtering part. The gas filtering-buffering device further comprises a gas inlet  1  provided at the one end of the first filter  33 , the gas to be processed flows into the first filter  33  through the gas inlet  1 , and a gas outlet  25  provided at the one end of the second filter  34 , the gas processed by above filter is discharged out of the second filter  34  via the gas outlet  25 . As shown in  FIG. 3 , the inlet-gas buffering cavity  4  is provided at the upstream of the first gas filtering part in a gas flow direction, the outgas buffering cavity  21  is provided at the downstream of the second gas filtering part in the gas flow direction. Although in the above embodiment, the gas filtering-buffering device includes the first filter  33  serving as the first filtering unit and the second filter  33  serving as the second filtering unit, the present invention is not limited thereto. Specifically, the gas filtering-buffering device of the present invention also can only have one filter, and a gas inlet and a gas outlet provided at both end of the filter. 
     Refer to  FIG. 3 , the first filter includes a first cartridge filter  8  having a substantially cylindrical shape, a first cartridge cover  36  provided at the left end of the first cartridge filter  8  and hermetically engaged with the first cartridge filter  8 . The second filter includes a second cartridge filter  17  having a substantially cylindrical shape, and the second cartridge cover  37  provided at the left end of the second cartridge filter  17  and hermetically engaged with the second cartridge filter  17 . Although, the first and second cartridge filters in the embodiment have a substantially hollow cylindrical shape, the present invention is not limited thereto, any other desirable shape also can be applied, for example, hollow cube shape. Furthermore, although in the above embodiment, the first filter  33  is structured of two separated parts consisting of the first cartridge filter  8  and the first cartridge cover  36  which are hermetically engaged with each other, the second filter  34  is structured of two separated parts consisting of the second cartridge filter  17  and the second cartridge cover  37  which are hermetically engaged with each other, the present invention is not limited thereto. In particular, the first filter  33  and the second filter  34  also may be formed integrally. 
     An built-in passage end plate  12  serving as a connection unit is hermetically provided at the right end of the first cartridge filter  8  and the second cartridge filter  17 , an built-in passage  13  is in communication with the first cartridge filter  8  and the second cartridge filter  17  is provided inside the built-in passage end plate  12 . In one embodiment, the built-in passage end plate  12  is configured to be separated parts, as shown in  FIG. 1 , which is hermetically connected with the filters  33 ,  34  by draw bars  10 ,  10 ′. However, the present invention is not limited thereto, for example, the built-in passage end plate  12  also can be configured to have an integrated structure with the first filter  33  and the second filter  34 . 
     Furthermore, the gas filtering-buffering device further includes a first draw bar  10  penetrating through the first filter  33  and connected with the first filter  33  and the built-in passage end plate  12 , and a second draw bar  10 ′ penetrating through the second filter  34  and connected with the second filter  34  and the built-in passage end plate  12 . 
     In one embodiment, the first filter  33  is constructed of two separated parts consisting of the first cartridge filter  8  and the first cartridge cover  36  which are hermetically engaged with each other, the central draw bars  10 ,  10 ′ are provided separately between the first cartridge cover  36  and the second cartridge cover  37  and the built-in passage end plate  12 . In one embodiment, both two central draw bars  10 ,  10 ′ are extended out of the first cartridge cover  36  and the second cartridge cover  37 , and locked by two locking nuts  29  respectively. Apparently, two central draw bars  10 ,  10 ′ also can be provided to locate inside of the first filter  33  and second filter  34  so as to connect both inner ends of the first filter  33  and second filter  34 . 
     As shown in  FIG. 2 , in one embodiment, a fixed distance sealing pressure plate  26  is connected at the left end of two central draw bars  10 ,  10 ′. The fixed distance sealing pressure plate  26  is pressed at the outside of the first cartridge cover  36  and the second cartridge cover  37  by locking nuts  29 . Sealing rings  28  set on the central draw bars are provided between the fixed distance sealing pressure plate  26  and the first and second cartridge covers  36 ,  37 , and all the parts are tightly fitted together by the rotating locking nut  29  tightly to achieve the gas tightness in the flow path. 
     In the embodiment shown in  FIG. 2 , the gas inlet  1  is provided on the first cartridge cover  36 , the inlet-gas buffering cavity  4  is provided inside the first cartridge cover  36 . The inlet-gas filtering part includes a porous filter medium baffle  7  provided at the right side of the inlet-gas buffering cavity  4  and moisture filter medium layer  9  provided inside the first filter  8 . The porous filter medium baffle  7  is used for maintaining and blocking moisture filter medium layer  9 , to prevent it from overflowing into the inlet-gas buffering cavity. The primary function of the moisture filter medium layer  9  is to remove the moisture in the gas, and the main component thereof may be of color silica gel. 
     In one embodiment, the first filter  33  further includes a precise filtering layer provided at the left side of the inlet-gas buffering cavity  4 , that is, between the inlet-gas buffering cavity  4  and the gas inlet  1 , and a precise filtering layer baffle  3  used for blocking and maintaining a precise filtering layer  2 . The primary purpose of the precise filtering layer  2  is to filter the dust etc. which has entered into the gas filtering-buffering device, and the main component thereof may be absorbent cotton. 
     In the embodiment shown in  FIG. 2 , the gas outlet  25  is provided on the second cartridge cover  37 , the outgas buffering cavity  21  is provided inside the second cartridge cover  37 . The outgas filtering part is constructed by the porous padding baffle  20  at the right side of the outgas buffering cavity  21 , the organic substance filter medium layer  16  and/or absorbing filter medium layer  15  inside the second cartridge filter  17 . The porous padding baffle  20  is used to maintain and block the organic substance filter medium layer  16  and/or absorbing filter medium layer  15 , in order to prevent them from overflowing into the inlet-gas buffering cavity  4 . The primary function of the organic substance filter medium layer  16  and/or absorbing filter medium layer  15  is to absorb the particles, and the essential component thereof may be such as active carbon or molecular sieve. 
     In an embodiment, the second filter  34  further includes an outgas precise filtering layer and an outgas precise filtering layer baffle provided at the left side of the outgas buffering cavity  21 , that is, a position between the outgas buffering cavity  21  and the gas outlet  25 . The primary purpose of the precise filtering layer  24  is to filter the filtering stuff component etc. mixed into the gas, and the essential component may be such as absorbent cotton. 
     Refer to  FIGS. 1 and 2 , the gas filtering-buffering device further comprises: first and second openings  38 , 38  provided at the first and second gas buffering cavity  4 ,  21 ; and first and second rotary covers  31 ,  31  movably connected onto and closing the first and second openings  38 , 38 . In the embodiment shown in  FIG. 2 , the first cartridge cover  36  and the second cartridge cover  37  are provided with rotary covers  31 ,  31  corresponding to the inlet-gas buffering cavity  4  and the outgas buffering cavity  21 , respectively. Sealing rings  30  are provided respectively between two rotary covers  31 ,  31  and the first cartridge cover  36  and the second cartridge cover  37 . The rotary covers  31  may be connected with the cartridge covers  36 ,  37  by threaded connection. Furthermore, a number of screw holes  32  for fixing and mounting the whole filter are provided respectively on the first cartridge cover  36 , the second cartridge cover  37 , and the built-in passage end plate  12 . 
     Hereafter, each filter medium baffle according to the embodiment of the present invention will be described in accordance with  FIG. 5 . As mentioned in  FIG. 5 , the precise filtering layer baffle  3  in the present invention may be a circular-shaped porous baffle, the porous filter medium baffle  7 , the porous padding baffle  20 , the outgas precise filtering layer baffle  23  and the precise filtering layer baffle  3  have a similar structure, these four baffles are freely mounted on the corresponding central draw bars  10 ,  10 ′ in series, respectively, wherein nuts  5 ,  18 ,  22 , and  27  for adjusting their positions are provided within the inlet-gas buffering cavity  4  and outgas buffering cavity  21 . In particular, screw-threads, which incorporate with above nuts  5 ,  18 ,  22  and  27 , are provided onto a proper location of the central draw bars  10 ,  10 ′, so that nuts  5 ,  18 ,  22  and  27  may be moved along central draw bars  10 ,  10 ′, therefore, the filtering precision of each filtering layer may be adjusted by moving each filter medium baffle  3 ,  7 ,  20 ,  23 . 
     When it is required to adjust the precision of each filtering layer in above, the user opens the rotary cover  31  first, and then wrenches the nuts  5 ,  18 ,  22  and  27  engaged with the central draw bars  10 ,  10 ′, so that each filter medium baffles  3 ,  7 ,  20 ,  20  may be moved along the central draw bars  10 ,  10 ′, thus, the filtering precision of precise filtering layers and the capacity of the buffering cavities can be adjusted. Furthermore, the replacement of the filter medium in the first and second filters  33 ,  34  also can be achieved through above operation. 
     More particularly, in the present invention, the filter medium in the moisture removing cavity can be compacted by adjusting the position of the porous filter medium baffle  7  at one side of the moisture filter medium layer  9 . At the same time, the capacity of the inlet-gas buffering cavity is controlled by changing the position of the porous filter medium baffle  7 , and the position of the porous filter medium baffle  7  on the central draw bar  10  may be adjusted by the adjusting nut  5 . 
     The absorbing filter medium  15  and the organic substance filter medium layer  16  filled inside of the second cartridge filter  17  are organic substance padding, the filter medium in the second cartridge filter  17  is compacted by adjusting the position of the porous padding baffle  20  at one side of the organic substance filter medium. At the same time, the capacity of the outgas buffering cavity is controlled by changing the position of the porous padding baffle  20 , the position of the porous padding baffle  20  on the central draw bar  10 ′ is adjusted by nut  18 . 
     The inlet-gas precise filtering layer  2  is a fiber filtering layer, and it is closely pasted on an inner wall close to the gas inlet side in the inlet-gas buffering cavity, the inlet-gas precise filtering layer baffle  3  is provided at the outside thereof and mounted on the central draw bar  10  in series, a pretension nut  27  is located at the outside of the inlet-gas precise filtering layer baffle  3  on the central draw bar, the degree of tightness of the inlet-gas precise filtering layer baffle  3  is varied by adjusting the pretension nut  27 , so that the precision of the filtering is changed. 
     The outgas precise filtering layer  24  is a fiber filtering layer, and it is closed pasted on an inner wall close to the gas outlet  25  side in the outgas buffering cavity, the outgas precise filtering layer baffle  23  is provided at the outside thereof and mounted on the central draw bar  10 ′ in series, a pretension nut  22  is located at the outside of the outgas precise filtrering layer baffle  23 , the degree of tightness of the outgas precise filtering layer baffle  23  is varied by adjusting the pretension nut, so that the precision of the filtering is changed. 
     In the gas filtering-buffering device of the present invention, there can be three or more gas filtering units as required by the determination of the precision of filtering and so on. 
     When the gas filtering-buffering device of the present invention operates normally, the gas to be processed is entered into the first filter  33  via the gas inlet  1 . The primary purification is obtained through the primary filtering by the inlet-gas precise filtering layer  2 . When the gas flows into the first filter  33  through the gas inlet with a smaller drift diameter, the flow rate of the gas become extremely fast and it is easy to form turbulent flow. Thus after the gas is purified through the inlet-gas precise filtering layer, first of all, the gas may be processed with expanded capacity, stabilized pressure, and balanced the concentration, the pressure and the rate of the gas in the inlet-gas buffering cavity  4 , then it flows into the first cartridge filter  8  to subject to a moisture removing process by passing through the porous filter medium baffle  7 ; and then, the gas flows into the second filter  34  via the built-in passage  13 , firstly, inside the second cartridge filter  17 , the organic substance in the gas is removed by filtration, and particles in the gas are absorbed, and then, the gas may be processed with expanded capacity, stabilized pressure, and balanced the concentration, the pressure and the rate of the gas by flowing into the outgas buffering cavity  21  through the porous padding baffle, then, the gas is purified by the outgas precise filtering layer  24  and discharged by gas outlet  26 . 
     It would be appreciated by those skilled in the art that many modifications, alterations and substitutions may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.