Patent Publication Number: US-7708464-B2

Title: Deaeration valve and compression bag equipped therewith

Description:
FIELD OF THE INVENTION 
   The present invention relates to a deaeration valve using two valve films made of synthetic resin, which is able to pass an airflow in one direction, and to a compression bag equipped with this deaeration valve. 
   BACKGROUND ART 
   Patent Reference No. 1: JP utility model application laid-open No. H06-697 
   Conventionally, compression bags are known in which an item for storage which is bulky as a result of containing air, such as clothing, bedding or the like, is contained, and then compressed by expelling the air contained therein, in such a manner that the item can be stored in a compact fashion. 
   The compression bag is provided with an opening for introducing and removing the item for storage, and this opening can be closed to seal off the interior of the bag hermetically, by means of a zip fastener or the like. Many compression bags are provided with deaeration valves having an air passage for expelling air from the interior of the bag. 
   There are deaeration valves having a composition in which two valve films made of synthetic resin are superimposed on each other. In these valves, rectangular valve films are used, and an air passage is provided by seal sections formed by bonding the longitudinal side edges of the valve films together, and air is allowed to pass through the two valve films from an inlet to an outlet, and the air passage is closable by the two valve films that closely contact together. 
   This deaeration valve has a simple structure, but there are drawbacks in slackening of the valve films and inverse flow of air. One of the reasons for this slackening is thought to be local instability in the tension of the valve films which occurs as a result of the fixed positional relation between the films in the aforementioned seal sections. 
   On the other hand, in one example of a device aimed at preventing inverse flow in a deaeration valve having the aforementioned structure, the patent reference No. 1 proposes bending of the air passage. However, although this deaeration valve makes it less liable for inverse flow to occur, it does not resolve the aforementioned problem, namely, the fact that the valve films are fixed together in the seal sections, thereby producing local instabilities in the tension of the valve films. 
   In view of the circumstances, it is an object of the present invention to provide a deaeration valve, and a compression bag equipped with a deaeration valve, whereby the tension of the valve film can be stabilized, and inverse flow of air can be prevented effectively in spite of a simple structure. 
   DISCLOSURE OF THE INVENTION 
   In order to achieve the aforementioned object, a first aspect of the present invention according to claim  1  provides a deaeration valve  1  comprising two films  11 ,  12  of synthetic resin that are placed one on the other and bonded at parts thereof together. An air passage  2  is formed that allows to pass air through the valve films from an inlet  2   a  to an outlet  2   b  and closable by means of the valve films  11 ,  12  that closely contact together. The air passage  2  is defined by two seal sections  21 ,  22 , which are formed by bonding the valve films  11 ,  12  together. The inlet  2   a  of the air passage  2  is defined by the straight line linking respective upward flow side end sections  21   a ,  221   a  of the seal sections  21 ,  22 , while the outlet  2   b  of the air passage  2  is defined by the straight line linking respective downward flow side end sections  21   b ,  223   b  of the seal sections  21 ,  22 . At least one of the downward flow side end sections  21   b ,  223   b  of the seal sections  21 ,  22  and the downward flow side edges  11   b ,  12   b  of the valve films  11 ,  12  are separated. A passage extension section  31  is provided on the downward flow side of the air passage  2 , and is defined by the outlet  2   b  of the air passage  2 , the line of extension  21   c ,  223   c  of the seal section  21 ,  22  on the downward flow side from the downward flow side end section  21   b ,  223   b  of at least one of the seal sections  21 ,  22 , and the downward flow side edges  11   b ,  12   b  of the valve films  11 ,  12 . The valve films  11 ,  12  are not bonded together at the lines of extension  21   c ,  223   c.    
   A second aspect of the present invention according to claim  2  provides the deaeration valve  1  according to claim  1 , which further comprises a non-sealed section  3  comprising a passage extension section  31  and a free section  32 . The free section  32  is adjacent to the passage extension section  31  or to the air passage  2  and the passage extension section  31 . The passage extension section  31  and the free section  32  are bounded by the line of extension  21   c ,  223   c  that defines the passage extension section  31 . The portions of valve film  11 ,  12  constituting the passage extension section  31  and the free section  32  form a single body. 
   A third aspect of the present invention according to claim  3  provides the deaeration valve according to claim  1  or  2 , wherein the dimension L 2   b  between the respective end sections of the first side seal section  21  and the second side seal section  22  at the outlet of the air passage  2  is smaller than the dimension L 2   a  between the respective end sections at the inlet of the air passage  2 . 
   A fourth aspect of the present invention according to claim  4  provides the deaeration valve according to claim  3 , wherein the first side seal section  21  has a linear form, and the second side seal section  22  comprises three sections that are an introduction section  221 , an intermediate section  222 , and an expulsion section  223 . The intermediate section  222  connects between the introduction section  221  and the expulsion section  223 . Regarding the second side seal section  22 , the intermediate section  222  is formed closer to the first side seal section  21  than the introduction section  221 , and the expulsion section  223  is formed closer to the first side seal section  21  than the intermediate section  222 . The inlet  2   a  of the air passage  2  is defined by the upward flow side end section  221   a  of the introduction section  221  and the upward flow side end section  21   a  of the first side seal section  21 , while the outlet  2   b  of the air passage  2  is formed by the downward flow side end section  223   b  of the introduction section  223  and the downward flow side end section  21   b  of the first side seal section  21 . The downward flow side end section  223   b  of the second side seal section  22  is formed further towards the upward flow side than the downward flow side end section  21   b  of the first side seal section  21 . The free section  32  being formed adjacent to the air passage  2  and the passage extension section  31  is provided. 
   A fifth aspect of the present invention according to claim  5  provides the deaeration valve according to any one of claims  1  to  4 , wherein, in the air passage  2 , the upward flow side edge  11   a ,  12   a  of the valve films  11 ,  12  that are placed one on the other, and the upward flow side edge  12   a ,  11   a  of the other of the valve films  12 ,  11  are disposed at least respectively in staggered positions towards the upward flow side and the downward flow side. 
   A sixth aspect of the present invention according to claim  6  provides the deaeration valve according to any one of claims  1  to  5 , wherein an inert liquid  4  such as silicon oil is disposed on at least part of the inner surfaces of the valve films  11 ,  12  in the air passage  2 . 
   A seventh aspect of the present invention according to claim  7  provides a compression bag equipped with a deaeration valve. As a compression bag  5 , it is formed with at least two bag films  51 ,  52  of synthetic resin that are placed one on the other and bonded at parts thereof together. The compression bag comprises a storage section  62  provided with an opening  61 , and a deaeration opening  63  for removing air in the storage section  62  other than the opening  61 . The storage section  62  is able to contain an item for storage. The respective bag films  51 ,  52  have a rectangular shape in a plan view. The opening  61  is provided in the upper part of the compression bag  5  and is hermetically closable by a closing means  61   a , while the deaeration opening  63  is provided in the lower part of the compression bag  5 . A deaeration valve  1  according to any one of claims  1  to  6  is installed between the storage section  62  and the deaeration opening  63  with the inlet side of the air passage  2  towards the top and the outlet side towards the bottom. The installation of the deaeration valve  1  is achieved by forming a unifying seal section  64  where the valve films  11 ,  12  and the bag films  51 ,  52  are bonded together. Except through the air passage  2 , air is prevented from flowing between the storage section  62  and the deaeration opening  63 . A heat resistant coating  7  is disposed on at least part of the inner surfaces of the valve films  11 ,  12  in the air passage  2 , and the part is taken in a portion that coincides with the unifying seal section  64 . 
   An eighth aspect of the present invention according to claim  8  provides the compression bag equipped with a deaeration valve according to claim  7 , wherein elongate films are used for the valve films  11 ,  12  and a plurality of the deaeration valves  1  are disposed parallel in the lengthwise direction of the valve films  11 ,  12  in such a manner that the air passages  2  and free sections  32  are respectively adjacent. 
   A ninth aspect of the present invention according to claim  9  provides the compression bag equipped with a deaeration valve according to claim  7  or  8 , wherein the storage section  62  comprises an item storage portion  62   a  and an air introduction portion  62   b , and the portions  62   a ,  62   b  are bounded by a valve protection seal  67 . The valve protection seal  67  is formed by bonding the bag films  51 ,  52  together. Air is allowed to pass between the item storage section  62   a  and the air introduction portion  62   b.    

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1(A)  is a plan view showing a deaeration valve relating to one embodiment of the present invention;  FIG. 1(B)  is a schematic cross-sectional view along line A-A in  FIG. 1(A) , when the air passage is open; and  FIG. 1(C)  is a schematic cross-sectional view along line A-A in  FIG. 1(A) , when the air passage is closed. 
       FIG. 2  shows a deaeration valve relating to one embodiment of the present invention during deaeration, in which  FIG. 2(A)  is a plan view of the feature of the valve;  FIG. 2(B)  is a schematic cross-sectional view along B-B in  FIG. 2(A) ;  FIG. 2(C)  is a schematic cross-sectional view along C-C in  FIG. 2(A) ; and  FIG. 2(D)  is a schematic cross-sectional view along D-D in  FIG. 2(A) . 
       FIG. 3  shows a deaeration valve relating to one embodiment of the present invention, at the moment when deaeration has finished, in which  FIG. 3(A)  is a plan view of the feature of the valve; and  FIG. 3(B)  is a schematic cross-sectional view along E-E in  FIG. 3(A) , showing a state where the valve is installed on a compression bag. 
       FIG. 4  shows a deaeration valve relating to one embodiment of the present invention, after finishing deaeration, in which  FIG. 4(A)  is a plan view of the feature of the valve;  FIG. 4(B)  is a schematic cross-sectional view along F-F in  FIG. 4(A) , showing a state where the valve is installed on a compression bag;  FIG. 4(C)  is a schematic cross-sectional view along G-G in  FIG. 4(A) ; and  FIG. 4(D)  is a schematic cross-sectional view along H-H in  FIG. 4(A) . 
       FIG. 5(A)  is a plan view showing a deaeration valve relating to a further embodiment of the present invention;  FIG. 5(B)  is a schematic cross-sectional view along line I-I in  FIG. 5(A) , when the air passage is open; and  FIG. 5(C)  is a schematic cross-sectional along line I-I in  FIG. 5(A) , when the air passage is closed. 
       FIG. 6  is a plan view showing a compression bag equipped with a deaeration valve relating to one embodiment of the present invention. 
       FIGS. 7(A)-7(H)  are schematic plan views showing other embodiments of a deaeration valve relating to the present invention. 
   

   BEST MODE TO PRACTICE THE INVENTION 
   One embodiment of the present invention will be described below with reference to the drawings.  FIG. 1  is a plan view showing a deaeration valve according to the present embodiment, and  FIG. 6  is a plan view showing a compression bag equipped with the deaeration valve of the present embodiment. The expressions “upward flow” and “downward flow” in the following description are based on the direction of the air flow when the air passage is open as shown in  FIG. 1(B) , and expressions indicating up, down, left and right relate to the positional situation shown in  FIG. 1(A)  and  FIG. 6 . Further, in expressions relating to “front” and “rear”, “front” indicates the upper side in the state shown in  FIGS. 1(B) and 1(C) , and “rear” indicates the lower side in these drawings. 
   As shown in  FIG. 1(A) , the deaeration valve  1  according to the present embodiment is open with respect to air flow f 1  in one direction from the upper side to the lower side (see FIG.  1 (B)), and it is closed with respect to air flow f 2  in the other direction from the lower side to the upper side (see  FIG. 1(C) ). This deaeration valve  1  is principally attached to a compression bag  5  such as that shown in  FIG. 6 , and is used in order to remove air in the storage section  62  of the compression bag  5 . Equipping of this deaeration valve  1  is not limited to a compression bag as in the present embodiment, and it may also be applied to a bag that is used to be filled with gases such as air. Further, the deaeration valve  1  may also be used as a check valve for general fluids such as gases other than air and liquids such as water. 
   The deaeration valve  1  according to the present invention comprises two valve films  11  and  12  of synthetic resin that are placed one on the other. In these valve films  11  and  12 , desirably, at least the surfaces forming the inner faces of the air passage  2  have weak contact property, thereby making the valve films  11  and  12  readily closely contact together. The valve films  11  and  12  used in the present embodiment have a rectangular shape as shown in  FIG. 1 , but they may also have another shape. 
   By bonding together a portion of the valve films  11  and  12 , for example, by heat seal, an air passage  2  is provided where air is allowed to pass through the valve films  11  and  12  from an inlet  2   a  to an outlet  2   b , and it is closable by the valve films  11  and  12  that closely contact together. This air passage  2  is defined by the two seal sections  21 ,  22  formed by bonding the valve films  11  and  12  together. 
   When the air flow f 1  passes in the aforementioned direction, as shown in  FIG. 1(B) , the valve films  11  and  12  are pushed apart forcibly and opened by the air flow f 1 . However, in all other cases, the valve films  11  and  12  closely contact together, as shown in  FIG. 1(C) . Therefore, the air passage  2  maintains a closed state in which the air flow f 2  in the other direction is not allowed to pass. The detailed movement of the valve films  11  and  12  with the air passage  2  closed will be described hereinafter. 
   In the present embodiment, the air passage  2  is constituted by the two valve films  11  and  12 , but as shown in  FIG. 5 , a structure may also be adopted in which an intermediate film  13  is disposed between the two valve films  11  and  12 , wherein the base end side of the intermediate film  13  is bonded to the rear side valve film  12 , as shown in  FIG. 5(B) , and the front end side thereof is movable inside the air passage  2  and able to make a close contact to the front side valve film  11 , as shown in  FIG. 5(C) . The air passage  2  may have a structure to be closable by the intermediate film  13  and the front side valve film  11  that closely contact together, in addition to the close contact between the valve films  11  and  12  described above. In the example illustrated here, the downward flow side edge of the intermediate film  13  is positioned further toward the upward flow side than the downward flow side edges  11   b  and  12   b  of the valve films  11  and  12 , but it is also possible for the positions of the respective edges  11   b ,  12   b  and  13   b  to be aligned with each other. 
   In the illustrated structure, desirably, the opposing faces of the rear side valve film  12  and the intermediate film  13 , which are separated except the base end section when the air passage  2  is closed, do not have a weak contact property in order to make the films  12  and  13  less liable to closely contact together. 
   In the deaeration valve  1  according to the present embodiment, as shown in  FIG. 1 , the aforementioned seal sections  21  and  22  comprise a first side seal section  21  which has a linear shape extending in the up/down direction in the figure, following the left-hand edge of the valve films  11 ,  12  in the figure, and a second side seal section  22  which is formed further on towards the right-hand side with respect to the first side seal section  21  in the figure, and which extends in the up/down direction in the figure, but is formed in a bent fashion. 
   The second side seal  22  in the present embodiment comprises three sections; an introduction section  221 , an intermediate section  222  and an expulsion section  223 , from the top downwards in the drawings. The introduction section  221  is disposed toward the inlet side of the air passage  2 , and the expulsion section  223  is disposed toward the outlet side of the air passage  2 . 
   Here, the upward flow side end  221   a  of the introduction section  221  and the upward flow side end  21   a  of the first side seal section  21  form the inlet  2   a  of the air passage. Specifically, the inlet  2   a  is defined by the straight line which links the respective end sections  221   a  and  21   a . Further, the downward flow side end  223   b  of the expulsion section  223  and the downward flow side end  21   b  of the first side seal section  21  form the outlet  2   b  of the air passage. More specifically, the outlet  2   b  is defined by the straight line which links the respective end sections  223   b  and  21   b . The intermediate section  222  is connected between the introduction section  221  and the expulsion section  223 . 
   In the second side seal  22 , the intermediate section  222  is formed more closely to the first side seal section  21  than the introduction section  221 , and the expulsion section  223  is formed more closely to the first side seal section  21  than the intermediate section  222 . Accordingly, the dimension L 2   b  between the respective end sections of the first side seal section  21  and the second side seal section  22  on the outlet side of the air passage  2  is smaller than the dimension L 2   a  between the respective end sections on the inlet side. In other words, the width of the air passage  2  in the present embodiment narrows toward the downward flow side. 
   In the present embodiment, each of the introduction section  221 , the intermediate section  222  and the expulsion section  223  is formed by straight lines, and as shown in  FIG. 1 , the introduction section  221  and the expulsion section  223  are formed in parallel with the first side seal section  21 . 
   The mode of the seal sections  21  and  22  is not limited to that shown in the present embodiment, and it may be modified in various ways. For example, it is also possible to dispose the respective seal sections  21  and  22  in a parallel fashion, as shown in  FIGS. 7(A) ,  7 (B) and  7 (H), by forming both of the seal sections  21  and  22  as straight lines, in such a manner that the air passage  2  does not narrow, and it is also possible to cause the air passage  2  to narrow by forming the second side seal section  22  as a straight line extending in an oblique direction, as shown in  FIG. 7(E) . Further, it is also possible to form the second side seal section  22  as a continuous curved line, as shown in  FIG. 7(F) . Moreover, in the case of the present embodiment, the first side seal section  21  is formed in a straight line and the second side seal section  22  is curved, but as shown in  FIG. 7(D) , it is also possible to form both of the seal sections  21  and  22  in curved lines, in a laterally symmetrical configuration. 
   In the deaeration valve  1 , as shown in  FIG. 1(A) , a non-sealed section  3  is formed outside the air passage  2 . This non-sealed section  3  consists of a passage extension section  31  and a free section  32 . Here, the passage extension section  31  is a portion located on the downward flow side from the outlet  2   b  of the air passage  2 , and air that has passed through the air passage  2  continues to pass through this section. On the other hand, the free section  32  is a section in which the valve films  11  and  12  are closed by a unifying seal  64  formed when installing the valve on the compression bag  5 , as shown in  FIG. 6 , for example, and air does not pass through this section as it does through the air passage  2 . As shown in  FIGS. 2(A) and 2(D) , a part of the air flow into the air passage extension section  31  from the air passage  2  may pass through the free section  32 . 
   Here, in the present embodiment, the downward flow side end  223   b  of the expulsion section  223  of the second side seal section  22  is formed further toward the upward flow side (the upper side in the figure) than the downward flow side end  21   b  of the first side seal section  21 . Therefore, the passage extension section  31  in the deaeration valve  1  according to the present embodiment is a triangular-shaped portion defined by three lines; the outlet  2   b , namely, the line linking the downward flow side end  21   b  of the first side seal section  21  and the downward flow side end  223   b  of the expulsion section  223  of the second side seal section  22 , the downward flow side edges  11   b  and  12   b  of the valve films  11  and  12 , and the line of extension  223   c  of the second side seal  22  on the downward flow side of the expulsion section  223  of the second side seal  22  (indicated by a broken line). When the air passage  2  is closed as shown in  FIG. 1(C) , the valve films  11  and  12  can closely contact together in this passage extension section  31 , as the valve films  11  and  12  in the air passage  2 . 
   In the present embodiment, as described above, by forming a first side seal section  21  further in the downward direction with respect to the second side seal section  22  in the figure, the first side seal  21  serves as a bone for the valve films  11  and  12  and prevents the valve films  11  and  12  from curling in the passage extension section  31 , and hence there is no obstacle to close contact of the valve films  11  and  12  in the passage extension section  31 . 
   As shown in  FIGS. 7(A) ,  7 (C) and  7 (H), it is also possible to separate the downward flow side edges  11   b  and  12   b  of the valve films  11  and  12  from the downward flow side end  21   b  of the first side seal section  21 , in such a manner that the respective seal sections  21  and  22 , and the downward flow side edges  11   b  and  12   b  of the valve films  11  and  12  are not connected. 
   The free section  32  is adjacent to both the air passage  2  and the passage extension section  31 . In other words, as shown in  FIG. 1 , in the non-sealed section  3 , the portion to the left-hand side of the downward flow side line of extension  223   c  of the expulsion section  223  of the second side seal  22  forms the passage extension section  31 , while the portion to the right-hand side forms the free section  32 . 
   The passage extension section  31  and the free section  32  are connected, and distortion of the valve films  11  and  12  in the passage extension section  31  can be absorbed in the free section  32 . Therefore, at least in the passage extension section  31 , the tension of the valve films can be stabilized, consequently eliminating slackening or wrinkles, and the valve films  11  and  12  can be made reliably to closely contact together. Inverse flow of the air in the air passage  2  can be effectively prevented by locating the portion where the valve films  11  and  12  closely contact together in this way adjacent to the downward flow side of the air passage  2 . 
   As described above, in order that a portion able to absorb distortion of the valve films  11  and  12  is ensured in the free section  32 , it is necessary for the unifying seal  64  formed in installation to the compression bag  5 , or for the seals formed separately from this in the free section  32  in order to prevent passage of air between the valve films  11  and  12 , to be formed from the upward flow side edges  11   a  and  12   a  of the valve films  11  and  12  in the free section  32 , up to the downward flow side end  223   b  of the expulsion section  223  of the second side seal  22 , and a gap must be provided between these seals and the downward side edges  11   b  and  12   b  of the valve films  11  and  12 . 
   Further, it is not essential to form the free section  32 , and depending on the circumstances, it is possible for the non-sealed section  3  to comprise the passage extension section  31  only, as shown in  FIG. 7(H) . In this case, the passage extension section  31  is a square portion defined by the four lines; the outlet  2   b , namely, the line linking the downward flow side end  21   b  of the first side seal section  21  and the downward flow side end  223   b  of the second side seal section  22 , the downward flow side edges  11   b  and  12   b  of the valve films  11  and  12 , the downward flow side line of extension  21   c  of the first side seal  21  and the downward flow side line of extension  223   c  of the second side seal  22 . 
   Even in this case, it is possible to eliminate distortion of the valve films  11  and  12  in the passage extension section  31 , by staggering the valve films  11  and  12  in the left/right direction in the figure, in the passage extension section  31 , and like the foregoing, the tension of the valve films can be stabilized, and the valve films  11  and  12  can be made reliably to closely contact together without slackening or wrinkles. 
   In addition to the foregoing, in the present embodiment, the width of the air passage  2  is narrowed toward the downwards flow side, and the lateral dimension of the free section  32  is greater in the figure than the lateral dimension of the passage extension section  31  in  FIG. 1(A) . More specifically, in the present embodiment, the lateral dimension of the passage extension section  31  is 10 mm in the figure, whereas the lateral dimension of the free section  32  is 70 mm in the figure. Thus, by forming the free section  32  larger than the passage extension section  31  in this way, the above-described absorption of distortion in the free section  32  is performed more effectively. 
   Here, the movement of the valve films  11  and  12  with the air passage  2  closed will be described in detail. As shown in  FIG. 6 , explained will be a state where a deaeration valve  1  is installed to the compression bag  5  described below. For description, the cross-sectional views in  FIG. 2  to  FIG. 4  exaggerate the size in the vertical direction of the figure, compared to an actual size. 
   First, when the air present inside the storage section  62  of the compression bag  5 , shown in  FIG. 6 , is removed, the opening  61  is closed by the closing means  61   a , and pressure is applied from outside the bag by rolling up the storage section  62  or doing like this. The air inside the storage section  62  forms an air flow f 1  and passes through the air passage  2  of the deaeration valve  1 , being expelled to the exterior of the bag. During this action the valve films  11  and  12  are pushed forcibly apart as shown in  FIG. 2(B)  of a sectional view along B-B. Here, as described above, since the second side seal section  22  ends at an intermediate point of the passage extension section  31 , the air flow f 1 , as shown by the arrow in  FIG. 2(A) , also flows to the free section  32 .  FIG. 2(C)  shows a sectional view along C-C in the lateral direction of the air passage  2  of the deaeration valve  1  in this case, while  FIG. 2(D)  shows a sectional view along D-D in the lateral direction of the passage extension section  31  and the free section  32  of the deaeration valve  1  in this case. 
   Next,  FIGS. 3(A) and 3(B)  show a momentary state when the aforementioned deaeration action has ended and the air flow f 1  has ceased to pass through the air passage  2 . In this case, the interior of the storage section  62  of the compression bag  5  assumes a state of negative pressure due to the expulsion of the air therein. Consequently, as shown in  FIG. 3(B)  of a sectional view along E-E, a force X acts on the valve films  11  and  12  in the air passage  2  so as to pull them towards the storage section  62 , and hence the valve films  11  and  12  closely contact together. 
   This close contact of the valve films  11  and  12  occurs within a very short period of time, and hence there is virtually no inverse flow of air through the air passage  2  during the movement of the valve films  11  and  12 . 
   Next,  FIGS. 4(A) to 4(D)  show the cases where the valve films  11  and  12  described above closely contact together, and the air passage  2  is closed. In this case, as shown in  FIG. 4(B)  of a sectional view along F-F, the valve films  11  and  12  normally closely contact to each other, thus closing the air passage  2  completely, but as shown in  FIG. 4(C)  of a sectional view along G-G in the lateral direction of the air passage  2  of the deaeration valve  1 , a gap Y may occasionally arise between the valve films  11  and  12  due to slackening of the valve films  11  and  12 . This is because the valve films  11  and  12  are fixed by the first side seal section  21  and the second side seal section  22 , and hence relative displacement between the valve films  11  and  12  is restricted. On the other hand, in the passage extension section  31 , the second side seal section  22  is not present, and therefore the valve films  11  and  12  are able to move in the direction of arrow Z, as shown in  FIG. 4(D)  of a sectional view along H-H in the lateral direction of the air passage  2  of the deaeration valve  1 . Consequently, it is possible to absorb any displacement between the valve films  11  and  12  in the free section  32 , and therefore, no gaps Y such as that in  FIG. 4(C)  occur, and the valve films  11  and  12  can be made reliably to closely contact together in the passage extension section  31 . 
   Even in the deaeration valve  1  comprising of three films  11  to  13  illustrated in  FIG. 5 , like the foregoing, the valve films  11  and  12  closely contact together due to a force X that pulls them towards the storage section  62 , but in addition to this, the intermediate film  13  and the front side valve film  11  closely contact together, as shown in  FIG. 5(C) , due to the aforementioned force X (in order to aid understanding, the valve films  11  and  12  are depicted in a separated fashion in  FIG. 5(C) ). Thereupon, a pocket-shaped space  2   c  may be provided between each of the valve films  11  and  12  and the intermediate film  13 , but even in this case, the air flow f 2  heading to flow inversely from the outlet  2   b  to the inlet  2   a  of the air passage  2  remains in this pocket-shaped space  2   c  and does not pass through the air passage  2 . 
   Here, it is desirable that the dimension of the inlet  2   a  of the air passage  2  is large, since the air is guided smoothly into the air passage  2 . Contrary to this, it is desirable that the dimension of the outlet  2   b  of the air passage  2  is small, since distortion is not liable to occur in the valve films  11  and  12 . And, it is desirable that the dimension of the air passage  2  from the inlet  2   a  to the outlet  2   b  is large in order to ensure that the valve films  11  and  12  closely contact together in a reliable fashion. However, the dimensions of the respective sections of the deaeration valve  1  will be determined by taking things into consideration, because balancing the dimensions with the size of the compression bag  5  to which the valve is applied, or ensuring a large storage section  62  in the compression bag  5  are functionally required. 
   With respect to the aforementioned dimensions, desirably, the lateral dimension between the introduction section  221  and the first side seal section  21  in the vicinity of the inlet  2   a  of the air passage  2  is taken to be 20 mm-60 mm. In the present embodiment, it is set as 30 mm. Further, desirably, the lateral dimension between the expulsion section  223  and the first side seal section  21  in the vicinity of the outlet  2   b  of the air passage  2  is taken to be 5 mm-30 mm. In the present embodiment, it is set as 10 mm. Desirably, the dimension of the deaeration valve  1  in the vertical direction in the figure is 30 mm-100 mm. In the present embodiment, the dimension falls on the upward flow side edge  12   a  and the downward flow side edge  12   b  of the rear side valve film, and is taken as 45 mm. 
   As described above, since the distance between the first side seal section  21  and the second side seal section  22  can be set freely, it is possible to design a deaeration valve  1  capable of passing the optimum amount of air through the air passage  2  in accordance with the size of the compression bag  5  to which the deaeration valve  1  is installed. 
   In the present embodiment, the dimension of the deaeration valve  1  in the lateral direction in the figure is taken as 80 mm, and the free section  32  has a dimension sufficiently larger than the passage extension section  31 , but depending on the circumstances, it is also possible to make the right-hand ends of the valve films  11  and  12  in the figure coincide with the introduction section  221  of the second side seal section  22 , as shown in  FIG. 7(G) , in such a manner that the free section  32  is formed solely between the expulsion section  223  of the second side seal section  22  and the right-hand ends of the valve films  11  and  12  in the figure. 
   Here, as shown in  FIGS. 1(A)-1(C) , the upward flow side edge  11   a  of the front side valve film  11  and the upward flow side edge  12   a  of the rear side valve film  12 , both of the valve films being placed one on the other, are disposed in staggered positions, displaced towards the upward flow side and the downward flow side. In the present embodiment, the upward flow side edge  11   a  of the front side valve film  11  is disposed towards the downward flow side. The aforementioned displacement is desirably set within the range of 1 mm to 10 mm, and more desirably, 3 mm to 5 mm. This displacement is not essential in the present invention, but is desirably to be provided. Also, this displacement may be called “step difference”. 
   The displacement between the edges  11   a  and  12   a  is provided in order to avoid the inlet  2   a  of the air passage  2  from being sealed due to dislocation of the unifying seal section  64  that is a heat seal formed between the deaeration valve  1  and each of the bag films  51  and  52  when bonding the deaeration valve  1  onto the bag films  51  and  52  as described hereinafter. Further, it also serves to make the valve films  11  and  12  readily open up during deaeration, in such a manner that the air flow f 1  can be smoothly introduced to the air passage  2  during deaeration. 
   In the present embodiment, as shown in  FIG. 1(A) , the dimension of the valve films  11  and  12  in the vertical direction in the figure is the same in the sections where the air passage  2  is formed and the other sections of the films, but it is effective as long as a displacement as described above exists in the section where the air passage  2  is formed. 
   An inert liquid  4 , such as silicon oil, is at least partly disposed between the inner surfaces of the valve films  11  and  12 . This liquid  4 , due to its viscosity, has effects of reinforcing close contact between the valve films  11  and  12  when the air passage  2  is sealed. Desirably, the liquid  4  has a low viscosity, since it is difficult to open up the air passage  2  if the viscosity is too high. However, even it is low, needed is the viscosity of a level that does not allow the liquid to leak out from the air passage  2 . 
   Next, the compression bag  5  equipped with the aforementioned deaeration valve  1  will be described. This compression bag  5  is formed with at least two bag films  51  and  52 , which are made of synthetic resin and placed one on the other, by partly bonding the films together. The compression bag  5 , as shown in  FIG. 6 , has a storage section  62  that includes an opening  61  and is able to contain an item such as clothing, and a deaeration opening  63  for removing air in the storage section  62  other than the opening  61 . In the compression bag  5  according to the present embodiment, the opening  61 , provided on the upper side in the figure, can be hermetically closed by a closing device, such as a fastener  61   a , which closes by way of interlocking a recessed strip with a projecting strip. The deaeration openings  63  are provided on the lower side of the compression bag  5  in the figure. However, the opening  61  and the deaeration openings  63  can be positioned freely as long as they do not affect in the status where the deaeration valve  1  is attached, as described hereinafter. As regards the number of deaeration openings  63 , in the compression bag  5  according to the present embodiment, three deaeration openings  63  are provided, but this number may be varied. Further, the bag films  51  and  52  according to the present embodiment have a rectangular shape in a plan view, but they may also be formed in a circular shape, a polygonal shape, or other forms variously. 
   The aforementioned deaeration valve  1  is, between the storage section  62  and a deaeration opening  63 , attached with the inlet side of the air passage  2  towards the top and the outlet side towards the bottom. In the present embodiment, it is positioned within a range of 60 mm from the bottom of the compression bag  5 . The deaeration valve  1  is attached through forming a unifying seal section  64  in which the valve films  11  and  12 , and the bag films  51  and  52  are bonded together. Except the air passage  2 , air does not flow between the storage section  62  and the deaeration opening  63  by forming this unifying seal section  64 . 
   In the present embodiment, elongate films are used as valve films  11  and  12 , and a plurality of deaeration valves  1  are disposed parallel in the lengthwise direction of these valve films, in such a manner that air passages  2  and free sections  32  are respectively adjacent, as shown in  FIG. 6 . Consequently, combined with similarly elongate bag films  51  and  52 , compression bags  5  can be continuously manufactured, resulting in enhancement of productive efficiency. Moreover, when a plurality of deaeration valves  1  are aligned in this fashion, the number of air passages  2  per compression bag  5  can be readily increased as the compression bag  5  becomes larger, especially extending the lateral dimension, and hence it is not difficult in deaeration with a large-size compression bags  5 . 
   Aforementioned unifying seal section  64  is formed by heat sealing. Therefore, a heat resistant coating  7  is provided at least on part of the inner surfaces of the valve films  11  and  12  in the air passage  2  of the deaeration valve  1 , further coinciding with the unifying seal section, more specifically, as shown in  FIG. 1(B) , in the vicinity of the inlet  2   a  of the air passage  2 , in order that the air passage  2  is not closed off due to melting of the valve films  11  and  12  under the effects of the heat applied during heat sealing. Here, “heat resistant” means a property whereby the material degenerates, by fusion, or the like, due to heat of the heat sealing operation, without affecting surrounding members, such as valve films  11  and  12 . 
   In a deaeration valve  1  consisting of three films  11  to  13  as illustrated in  FIG. 5 , a heat resistant coating  7  is provided on the surface of the valve film  11  or the intermediate film  13  facing onto the space which is formed when the valve is opened and where the air flow f 1  passes, specifically, on the surface adjacent to the inlet  2   a  of the air passage  2 , as shown in  FIG. 5(B) . 
   In the compression bag  5  according to the present embodiment, the storage section  62  comprises an item storage portion  62   a  where an item is actually contained, and an air introduction portion  62   b  which lies between the item storage portion  62   a  and the deaeration valve  1 , wherein valve protection seals  67  are formed at the boundary between these portions  62   a  and  62   b . The valve protection seals  67  are formed by intermittently bonding the bag films  51  and  52  together. The interval at which the valve protection seals  67  are formed may be such that air is allowed to pass between the portions  62   a  and  62   b  and the seals do not affect the introduction of air into the air passages  2 . In the present embodiment, the dimension of each valve protection seal  67  is 10 mm in the left/right direction in the figure, and the interval between the valve protection seals  67  is 25 mm. Further, the form of the valve protection seals  67  can be modified variously, however, it is desirable they have a form, for example, such as a circular form, which makes less resistance when air passes between the portions  62   a  and  62   b.    
   Forming of the valve protection seals  67  in this way enables the item such as clothing contained in the item storage portion  62   a  to be prevented from being sucked into the air passages  2  by the air flows f 1 . And, even when stuffing of the item into the item storage portion  62   a  makes the bag films  51  and  52  curve, portions of the bag films  51  and  52 , namely, the downward flow side films  51   a  and  52   a  situated in the air introduction portion  62   b , do not follow the curving, achieving a non-deformed state. Consequently, it is possible for the deaeration valves  1  to maintain a flat state without being affected by the stuffed item, resulting in opening and closing the air passages  2  reliably. However, it is not essential to form these valve protection seals  67 , and they may be omitted. 
   Next, a concrete description is given of a method of manufacturing the deaeration valve  1  shown in  FIG. 1  and the compression bag  5  shown in  FIG. 6 . 
   A long film rolled up in the form of a roll is used for the valve films  11  and  12  according to the present embodiment. Specifically, a film having a width of 45 mm and a length of 1000 m is used. 
   First, a heat resistant coating  7  is coated by means of gravure printing or the like onto part of the surface of the rear side valve film  12  facing the front side valve film  11 , specifically, in the vicinity of the position where the inlet  2   a  of the air passage  2  is to be formed. The width dimension of the front side valve film  11  is then reduced by approximately 5 mm. This dimensional difference forms the above-described displacement of the edges  11   a  and  12   a.    
   Either of the valve films  11  and  12  is coated with silicon oil  4  onto the surface of the portion where an air passage  2  is to be formed. This coating operation may be performed by painting with a brush or the like, or by spraying. 
   The two valve films  11  and  12  are then placed one on the other, and a first side seal section  21  and a second side seal section  22  are formed by heat sealing the films, as illustrated in  FIG. 1(A) . The first side seal section  21  is formed throughout the whole width of the valve films  11  and  12  in this operation. On the other hand, the downward flow side end section  223   b  of the second side seal section  22  does not coincide with the downward flow side edges  11   b  and  12   b  of the valve films  11  and  12 , thus providing a gap. This gap is the line of extension  223   c  of the seal section  22 , which forms the boundary between the passage extension section  31  and the free section  32  described above. 
   The deaeration valve  1  formed, as shown in  FIG. 1(A) , in this way is sandwiched between the bag films  51  and  52 , and the unifying seal section  64  is formed, thereby unifying the valve and the bag films. Side seal sections  65  are then formed on the perimeter edges of the bag films  51  and  52 , except the portions where the opening  61  and the deaeration opening  63  are to be formed. At the opening  61 , a fastener  61   a  of a closing means is attached. Further, as needed, a slider  8  is provided to aide opening and closing of the zip fastener  61   a . Thus the compression bag  5  is completed. 
   Depending on conditions between the position where the heat resistant coating  7  is deposited in the deaeration valve  1 , and the bag films  51  and  52 , heat sealing is ineffective at the portion where the heat resistant coating  7  overlaps, thus the side seal sections  65  are not formed, and hence air may leak. In the present embodiment, in order to prevent disadvantage like this, inner seal sections  66  are further formed to the inner side from the side seal sections  65  formed on the right and left-hand edges of the compression bag  5  in the figure. In other words, the deaeration valve  1  is sure to be bonded to the bag films  51  and  52  at the side seal section  65  and/or inner seal section  66 , except the portion such as the free section  32  where the heat resistant coating  7  is provided. 
   The deaeration valve  1  is not fixed to the bag films  51  and  52  at any positions other than the unifying seal section  64 , the side seal sections  65  and the inner seal sections  66 . Therefore, as described above, the free section  32  is hardly disturbed in absorbing distortion of the valve films  11  and  12  in the passage extension section  31 . 
   The present invention has the following beneficial effects. 
   In the aspect according to claim  1 , distortion in the valve films  11  and  12  in the passage extension section  31  can be eliminated, and therefore, at least in this passage extension section  31 , the tension of the valve films can be stabilized, and the valve films  11  and  12  can be reliably made to closely contact together without slackening or wrinkles. Since the reliable portion of close contact like this between the valve films  11  and  12  is located adjacent to the outlet  2   b  of the air passage  2 , it is possible to effectively prevent inverse flow of air in the air passage  2 . Consequently, a deaeration valve that is capable of effective prevention of inverse air flow in spite of a simple structure is provided. 
   In the aspect according to claim  2 , in addition the foregoing effects, a free section  32 , which is a section adjacent to the passage extension section  31 , or adjacent to the air passage  2  and the passage extension section  31 , is formed, and the parts of the valve films  11  and  12  forming the passage extension section  31  and the free section  32  form a single body. Therefore, distortion of the valve films  11  and  12  in the  131  can be absorbed in the free section  32 , whereby the tension in the valve films can be stabilized, at least in this passage extension section  31 , and the valve films  11  and  12  can be reliably made to closely contact together without slackening or wrinkles. 
   In the aspect according to claim  3  or  4 , in addition to the effects of the aspects above, the dimension L 2   b  between the respective end sections of the first side seal section  21  and the second side seal section  22  on the outlet side of the air passage  2  is made smaller than the dimension L 2   a  between the respective end sections on the inlet side, and therefore it is possible to form the free section  32  to a larger size than the passage extension section  31 , and a deaeration valve in which distortion is absorbed more effectively in the free section  32  is provided. 
   In the aspect according to claim  5 , in addition to the effects of the aspects described in claims  1  to  4 , the upward flow side edge  11   a ,  12   a  of the valve film  11 ,  12  on one side and the upward flow side edge  12   a ,  11   a  of the valve film  12 ,  11  on the other side are disposed in staggered positions, towards the upward flow side and the downward flow side respectively, and therefore, it is possible to prevent the inlet  2   a  of the air passage  2  from being bonded and closed off, when the deaeration valve  1  is bonded onto the bag films  51  and  52  that form the compression bag  5 . Further, this also has the action of facilitating opening of the valve films  11  and  12  during deaeration, in such a manner that the air flow f 1  is smoothly introduced into the air passage  2  during deaeration. 
   In the aspect according to claim  6 , in addition to the effects of the aspects described in any one of claims  1  to  5 , an inert liquid  4  such as silicon oil is provided on at least part of the inner surfaces of the valve films  11  and  12  in the air passage  2 , and therefore close contact between the valve films  11  and  12  with the air passage  2  closed can be reinforced by the viscosity of the liquid  4 . 
   In the aspect according to claim  7  is provided a compression bag equipped with a deaeration valve capable of stabilizing tension of the valve films  11  and  12  and effective prevention of inverse air flow in spite of a simple structure, and since a heat resistant coating  7  is provided on at least part of the inner surfaces of the valve films  11  and  12  in the air passage  2  of the deaeration valve  1 , then it is possible to provide a compression bag equipped with a deaeration valve in which the air passage  2  is not closed off as a result of melting of the valve films  11  and  12  due to the effects of heat during heat sealing for forming the compression bag  1 . 
   In the aspect according to claim  8 , in addition to the effects of the aspect described in claim  7 , long films are used for the valve films  11  and  12 , and a plurality of the aforementioned deaeration valves  1  are arranged in the lengthwise direction of the valve films  11  and  12  in such a manner that the respective air passages  2  and free sections  32  are adjacent, and therefore, combined with similarly elongate bag films  51  and  52 , it is possible to continuously manufacture compression bags  2 , resulting in enhancement of productive efficiency. Further, by arranging a plurality of deaeration valves  1  in this way, it is possible to readily increase the number of air passages  2  per compression bag  5 , as the size, and especially, the width, of the compression bag  5  increases, and therefore it is possible to provide a compression bag equipped with a deaeration valve in which there is no difficulty in performing deaeration, even in the case of a large compression bag  5 . 
   In the aspect according to claim  9 , in addition to the effects of the aspects described in claim  7  or  8 , valve protection seals  67  are formed at the boundary between an item storage portion  62   a  and an air introduction portion  62   b , and therefore it is possible to provide a compression bag equipped with a deaeration valve capable of preventing the item such as clothing contained in the item storage portion  62   a  from being sucked into the air passage  2 . Further, even when the bag films  51  and  52  are caused to curve when an item is stuffed into the item storage portion  62   a , the portions of the bag films  51  and  52  located in the air introduction portion  62   b  do not curve accordingly, and can be maintained in a non-deformed state. Therefore, it is possible to maintain the deaeration valve  1  in a flat state, without being affected by the contained item, and hence it is possible to provide a compression bag equipped with a deaeration valve in which the air passage  2  can be opened and closed in a reliable manner.