Patent Publication Number: US-2020290527-A1

Title: Sound insulation structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Priority is claimed on Japanese Patent Application No. 2019-047145, filed on Mar. 14, 2019, the contents of which are incorporated herein by reference. 
     BACKGROUND 
     Field of the Invention 
     The present invention relates to a sound insulation structure. 
     Background 
     In a vehicle such as an automobile, a building, and the like, in order to prevent noise from entering an internal space from the outside or prevent noise from being leaked from the internal space to the outside, a sound insulation material having a sound insulation performance is provided on a compartment member that compartmentalizes the outside and the internal space. 
     For example, Japanese Unexamined Patent Application, First Publication No. 2010-265589 discloses a configuration in which a spacer having a plurality of recess parts are arranged as a sound insulation material between a compartment member (roof plate) and a porous base material on an internal space side. According to such a configuration, noise (sound waves) entering from the compartment member side enters the inside of the recess part formed on the spacer and is reflected at the inside of the recess part, and thereby, a sound insulation performance is exerted. 
     Further, Japanese Unexamined Patent Application, First Publication No. 2003-104135 discloses a configuration in which a urethane layer is mounted as a sound insulation material on a compartment member (vehicle floor plate), noise is attenuated by the urethane layer, and a sound insulation property is exerted. In this configuration, a mass layer having a plate shape is mounted on the urethane layer, and thereby, the configuration includes a sound insulation structure in which the mass layer is used as a mass, and the urethane layer is used as a spring. 
     Japanese Unexamined Patent Application, First Publication No. 2006-123614 discloses a configuration in which a sound insulation material made of a foamed porous material or a fiber material is arranged in a bag formed of a film, and a sealing gas is sealed in the bag. 
     SUMMARY 
     Enhancing the sound insulation property is always desired. For example, in an automobile, a material that forms an outer panel of a vehicle body may be changed from an iron-based material to an aluminum-based material or a resin-based material, for example, in order to improve a fuel consumption rate by reducing the weight of the automobile or the like. Thereby, the sound insulation property of the outer panel itself may be degraded, and further enhancement of the sound insulation property is required. 
     However, in conventional techniques such as those disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-265589, Japanese Unexamined Patent Application, First Publication No. 2003-104135, and Japanese Unexamined Patent Application, First Publication No. 2006-123614, in order to further enhance the sound insulation property, it is necessary to increase the thickness of the sound insulation material. However, as the thickness of the sound insulation material increases, the weight and cost increase in accordance with the increase of the usage amount of the sound insulation material. 
     An aspect of the present invention provides a sound insulation structure capable of enhancing a sound insulation property while preventing a weight increase and a cost increase. 
     A sound insulation structure according to a first aspect of the present invention includes: a mass part which is arranged to be spaced from a compartment member that compartmentalizes an internal space of a structure body and an outside, and at least part of which has a flat surface shape; and a plurality of spring parts that are arranged on a side facing the compartment member in the mass part, wherein the spring part includes: a hollow film material having airtightness and flexibility; and a gas encapsulated within the film material, and the film material includes a recess part on one surface which is at least one of surfaces on the compartment member side and the mass part side. 
     A second aspect of the present invention is the sound insulation structure according to the first aspect wherein the recess part may be formed in a circumferential shape. 
     A third aspect of the present invention is the sound insulation structure according to the first or second aspect which may include a sound insulation member including the mass part and the spring part, wherein the sound insulation member may be provided on a side facing the compartment member of the spring part and may further include a joint layer member capable of being joined to the compartment member. 
     A fourth aspect of the present invention is the sound insulation structure according to the third aspect, wherein the mass part may be made of a polypropylene, the film material may be made of an ethylene-vinyl alcohol copolymer, and the joint layer member may be made of a polyethylene. 
     A fifth aspect of the present invention is the sound insulation structure according to any one of the first to fourth aspects, wherein the mass part may be formed of a material having a larger specific gravity than that of the film material of the spring part. 
     A sixth aspect of the present invention is the sound insulation structure according to any one of the first to fifth aspects, wherein the film material of the spring part may be formed of a material having a lower Young&#39;s modulus than that of the mass part. 
     A seventh aspect of the present invention is the sound insulation structure according to any one of the first to sixth aspects, wherein the plurality of spring parts may be arranged to be spaced from each other in a direction along an opposing surface that opposes the compartment member. 
     An eighth aspect of the present invention is the sound insulation structure according to any one of the first to seventh aspects, wherein the gas may be an air. 
     A ninth aspect of the present invention is the sound insulation structure according to any one of the first to seventh aspects, wherein the gas may be a carbon dioxide or a helium. 
     A tenth aspect of the present invention is the sound insulation structure according to any one of the first to ninth aspects, wherein the structure body may be a vehicle body of an automobile, and the compartment member may be an outer panel of the vehicle body or an inner panel that forms an interior of the vehicle body. 
     According to the first aspect of the present invention, it is possible to constitute a sound insulation structure in which the mass part is used as a mass, and the spring part is used as a spring. Accordingly, by appropriately adjusting the mass of the mass part and a spring constant of the spring of the spring part, a frequency at which the mass part resonates to noise is adjusted, and it is possible to efficiently reduce the noise in a target frequency range. 
     Further, since the sound insulation structure is a configuration in which the gas is encapsulated within the hollow film material, the usage amount of a material that forms the film material is greatly less than that of the urethane layer. Accordingly, even if the thickness of the sound insulation structure in a direction in which the mass part and the compartment member face each other is increased, it is possible to enhance a sound insulation property while preventing a weight increase and a cost increase. 
     Here, the pressure (that is, an internal pressure of the film material) of the gas encapsulated within the film material is varied in response to, for example, an external environment. According to the variation of the pressure of the gas, the spring part is expanded, and it is conceivable that, for example, a layout space of the spring part, a durability of the spring part, the spring constant, and the like are affected. 
     Therefore, according to the first aspect of the present invention, the recess part is formed on the film material, and the recess part is made deformable in response to the pressure of the gas. Accordingly, by deforming the recess part, for example, in response to a low-pressure environment at a high altitude or a high-temperature environment, it is possible to prevent the variation of the pressure (that is, the internal pressure of the film material) of the gas. Thereby, the expansion of the spring part can be prevented, and, for example, “preventing the spring part from affecting the layout space”, “ensuring the durability of the spring part”, and “ensuring the sound insulation property by preventing the increase of the spring constant” can be realized. 
     According to the second aspect of the present invention, the recess part is formed in a circumferential shape. Accordingly, for example, it is possible to smoothly deform the entire region of the recess part in response to the low-pressure environment at a high altitude or the high-temperature environment. Thereby, it is possible to favorably prevent the variation of the pressure (that is, the internal pressure of the film material) of the gas. 
     According to the third aspect of the present invention, the sound insulation member is constituted of the mass part and the spring part, and the joint layer member is provided in the sound insulation member on the side facing the compartment member of the spring part. Thereby, the sound insulation structure can be joined to the compartment member by the joint layer member, and the sound insulation structure can be easily provided on the compartment member. 
     According to the fourth aspect of the present invention, by forming the mass part using the polypropylene, it is possible to obtain a high moldability. Further, by forming the film material using the ethylene-vinyl alcohol copolymer, a high airtightness can be obtained, and it is possible to prevent the leakage of the gas encapsulated within the film material. 
     Furthermore, by forming the joint layer member using the polyethylene, the joint layer member can be easily and reliably joined to the compartment member. 
     According to the fifth aspect of the present invention, the specific gravity of the mass part is larger than the specific gravity of the film material, and thereby, the function of the mass part as the mass can be effectively exerted. 
     According to the sixth aspect of the present invention, the Young&#39;s modulus of the film material is smaller than the Young&#39;s modulus of the mass part, and thereby, the spring part is easily deformed elastically, and it is possible to efficiently reduce the noise. 
     According to the seventh aspect of the present invention, the plurality of spring parts are provided to be spaced from each other in the direction along the opposing surface, and thereby, when the spring part is elastically deformed in accordance with the displacement of the mass part so as to approach and be separated from the compartment member side, it is possible to prevent the spring parts adjacent to each other from interfering with each other. Thereby, it is possible to prevent another spring part from blocking the deformation of the spring part, and it is possible to efficiently reduce the noise. 
     According to the eighth aspect of the present invention, by using air as the gas encapsulated in the film material, it is possible to reduce costs. 
     According to the ninth aspect of the present invention, by using carbon dioxide as the gas encapsulated in the film material, a sonic speed (a propagation speed of sound waves) is reduced compared to a case in the air, and it is possible to improve the sound insulation performance Further, by using helium as the gas encapsulated in the film material, a density becomes lower than that of the air, and it is possible to improve the sound insulation performance 
     According to the tenth aspect of the present invention, the sound insulation structure such as those described above is provided on the inner panel or the outer panel of the vehicle body of the automobile, and thereby, it is possible to enhance the sound insulation property in the internal space of the vehicle body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view showing a vehicle body that includes a sound insulation structure according to an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view showing a roof part of the vehicle body that includes the sound insulation structure according to the embodiment. 
         FIG. 3  is a perspective view of the roof part of the vehicle body that includes the sound insulation structure according to the embodiment when seen from a vehicle outside. 
         FIG. 4  is a cross-sectional view along a IV-IV line of  FIG. 3  showing the sound insulation structure according to the embodiment. 
         FIG. 5  is a bottom view seen from a V arrow direction of  FIG. 4  showing an arrangement of a spring part in the sound insulation structure according to the embodiment. 
         FIG. 6  is a cross-sectional view showing the sound insulation structure according to the embodiment. 
         FIG. 7  is a view showing a model of the sound insulation structure according to the embodiment. 
         FIG. 8  is a side view showing a sound insulation structure of a comparison example. 
         FIG. 9  is a graph showing a transmission loss of the sound insulation structure according to the embodiment and the sound insulation structure according to the comparison example. 
         FIG. 10  is a cross-sectional view of a sound insulation structure according to a first modified example of the embodiment. 
         FIG. 11  is a cross-sectional view of a sound insulation structure according to a second modified example of the embodiment. 
         FIG. 12A  is a cross-sectional view of a sound insulation structure according to a third modified example of the embodiment. 
         FIG. 12B  is a plan view of a spring part according to the third modified example of the embodiment. 
         FIG. 13  is a bottom view showing an arrangement of a spring part in a sound insulation structure according to a fourth modified example of the embodiment. 
         FIG. 14  is a cross-sectional view along a XIV-XIV line of  FIG. 13  in the sound insulation structure according to the fourth modified example of the embodiment. 
         FIG. 15  is a bottom view showing an arrangement of a spring part in a sound insulation structure according to a fifth modified example of the embodiment. 
         FIG. 16  is a cross-sectional view showing a roof part of a vehicle body that includes a sound insulation structure according to a sixth modified example of the embodiment. 
         FIG. 17  is an enlarged cross-sectional view of a main part of the sound insulation structure according to the sixth modified example of the embodiment. 
         FIG. 18  is a cross-sectional view showing a roof part of a vehicle body that includes a sound insulation structure according to a seventh modified example of the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, an arrow FR indicates a frontward direction of a vehicle, an arrow UP indicates an upward direction of the vehicle, and an arrow LH indicates a leftward direction. The embodiment is described using an example in which a structure body is a vehicle body  1  of an automobile; however, the structure body is not limited to the vehicle body  1  of the automobile. 
     As shown in  FIG. 1 , the vehicle body  1  of the automobile includes a vehicle body main body  1 A, right and left front side doors  1 B, right and left rear side doors  1 C, a bonnet  1 D, a tail gate  1 E, right and left quarter panels  1 F (the right quarter panel  1 F is not shown), and a roof part  1 G. 
     The embodiment is described using an example in which the roof part  1 G includes a sound insulation structure; however, the embodiment is not limited thereto. As another example, the right and left front side doors  1 B, the right and left rear side doors  1 C, the bonnet  1 D, the tail gate  1 E, the right and left quarter panels  1 F, the roof part  1 G, or the like can include the sound insulation structure. 
     As shown in  FIG. 2  and  FIG. 3 , the sound insulation structure according to the present embodiment includes a sound insulation member  10 . 
     The sound insulation member  10  is provided between an outer panel (compartment member)  5  of the roof part  1 G and an inner panel (roof garnish, compartment member)  6  that faces an internal space  3  in the vehicle body  1  and forms an interior. The sound insulation member  10  is fixed to a lower surface of the outer panel  5 . 
     As shown in  FIG. 4  and  FIG. 5 , the sound insulation member  10  includes a mass part  11 , a spring part  12 , and a joint layer member  13 . The sound insulation member  10  is arranged in a space between the outer panel  5  and the inner panel  6  (refer to  FIG. 2 ). 
     The mass part  11  has, for example, a plate shape and is arranged to be spaced from the outer panel  5  that compartmentalizes the internal space  3  of the vehicle body  1  and an outside  4  (refer to  FIG. 2 ). The mass part  11  can be preferably formed of a material having a higher formability and a larger specific gravity than that of a film material  14  of the spring part  12  described below. 
     For example, polypropylene (PP) can be preferably used as a material that forms such a mass part  11 . The shape of the mass part  11  is not limited to a plate shape, and the mass part  11  may be a member having a flat surface shape at least in part. 
     A plurality of spring parts  12  are arranged to be spaced from each other along an opposing surface on a side that opposes the outer panel  5  in the mass part  11 . In the present embodiment, the spring parts  12  are arranged in a stagger form along the mass part  11 . 
     Each spring part  12  includes a hollow film material  14  and a gas  15  (also refer to  FIG. 6 ) encapsulated within the film material  14 . 
     As shown in  FIG. 6 , the film material  14  defines a tubular shape that extends in a direction as an axis line in which the mass part  11  and the outer panel  5  face each other. The film material  14  defines a sealed container shape that integrally includes a tubular part  14   a , a recess  14   b , a first end closure part (one surface)  14   c , and a second end closure part (one surface)  14   d . The film material  14  is formed of a material having airtightness and flexibility. 
     The film material  14  can be preferably formed of a material having a lower Young&#39;s modulus than that of a material forming the mass part  11  such that the film material  14  is elastically deformed more actively than the mass part  11 . For example, ethylene-vinyl alcohol copolymer (for example, Kuraray “EVAL” (registered trademark)) can be preferably used as the material forming such a film material  14 . The “airtightness” of the film material  14  is not limited to forming a closed space having completely no inflow or outflow of air, but it is also possible to permit some inflow and outflow of air such that the film material  14  can function as the spring part. 
     The tubular part  14   a  is formed such that the cross-sectional shape seen from the direction in which the mass part  11  and the outer panel  5  face each other is, for example, a circular tubular shape. A first end part  14   e  on the outer panel  5  side of the tubular part  14   a  is closed by the first end closure part  14   c  and the recess part  14   b . The first end closure part  14   c  is formed in a flat annular shape along the outer panel  5 . The first end closure part  14   c  is integrally joined, for example, to the outer panel  5  by the joint layer member  13 . The joint layer member  13  is described later in detail. 
     The recess part  14   b  is formed in a recess shape on an inner circumferential portion of the first end closure part  14   c . The recess part  14   b  is formed, for example, coaxially with respect to the tubular part  14   a . The recess part  14   b  has a bottom portion  14   f  and a side wall  14   g . The bottom portion  14   f  is formed in a flat circular plate along the outer panel  5 . The bottom portion  14   f  is arranged to be spaced toward the mass part  11  side relative to the first end closure part  14   c.    
     The side wall  14   g  extends cylindrically toward the outer panel  5  side from an outer circumference of the bottom portion  14   f  to an inner circumferential portion of the first end closure part  14   c . The side wall  14   g  is formed such that the cross-sectional shape seen from the direction in which the mass part  11  and the outer panel  5  face each other is, for example, a circumferential shape. That is, the recess part  14   b  is formed in a circumferential recess shape. 
     A second end part  14   h  on the mass part  11  side of the tubular part  14   a  is closed by the second end closure part  14   d . The second end closure part  14   d  is formed to be flat along the mass part  11 . The second end closure part  14   d  is integrally joined, for example, to the mass part  11  by an adhesive, welding, or the like. 
     That is, the film material  14  of the spring part  12  has the recess part  14   b  at the first end closure part  14   c  on the outer panel  5  side. Accordingly, the film material  14  is set (adjusted) such that a cross-sectional area of a region  14   i  that includes the recess part  14   b  is smaller than that of another region  14   j . Thereby, a spring constant k (refer to  FIG. 7 ) of the spring part  12  can be preferably lowered, and a resonance frequency by the sound insulation member  10  can be lowered. 
     Further, the recess part  14   b  is formed to be deformable in response to the pressure of a gas  15  encapsulated within the film material  14 . That is, for example, the recess part  14   b  is formed such that, by deforming the side wall  14   g  in response to the pressure of the gas  15 , the bottom portion  14   f  is movable in an arrow A direction (that is, in the direction in which the mass part  11  and the outer panel  5  face each other). 
     Thereby, by deforming the recess part  14   b , for example, in response to a low-pressure environment at a high altitude or a high-temperature environment, it is possible to prevent the variation of the pressure (that is, the internal pressure of the film material  14 ) of the gas  15 . 
     Accordingly, the expansion of the spring part  12  can be prevented, and, for example, “preventing the spring part  12  from affecting the layout space”, “ensuring the durability of the spring part  12 ”, and “ensuring the sound insulation property by preventing the increase of the spring constant k” can be realized. 
     The side wall  14   g  is formed in a circumferential shape. Therefore, for example, it is possible to smoothly deform the entire region of the recess part  14   b  in response to the low-pressure environment at a high altitude or the high-temperature environment. Thereby, it is possible to favorably prevent the variation of the pressure (that is, the internal pressure of the film material  14 ) of the gas  15 . 
     The detailed reason for the first end closure part  14   c  of the film material  14  including the recess part  14   b  will be described below in detail. 
     The embodiment is described using an example in which the recess part  14   b  is formed on the first end closure part  14   c  on the outer panel  5  side; however, the embodiment is not limited thereto. As another example, the recess part  14   b  can be formed on the second end closure part  14   d  on the mass part  11  side. 
     The gas  15  is filled in the inside of the hollow film material  14  to a preset pressure or more at least such that the looseness of the film material  14  is eliminated. 
     For example, air can be used as such gas  15 . 
     Further, carbon dioxide and helium can be also used as the gas  15 . 
     The joint layer member  13  is provided on a side facing the outer panel  5  in the spring part  12 . In this embodiment, the joint layer member  13  defines a membrane shape and is formed to cover a plurality of spring parts  12  (refer to  FIG. 4 ). 
     Such a joint layer member  13  is formed of a material capable of being joined to the outer panel  5 . In this embodiment, the joint layer member  13  is joined to the outer panel  5  by welding using ultrasonic waves, heat, or the like. Therefore, the joint layer member  13  can be preferably formed of a material having an excellent weldability with respect to the outer panel  5 . For example, polyethylene (PE) can be used as the material that forms such a joint layer member  13 . The joint layer member  13  may be joined to the outer panel  5  by an adhesive layer or an adhesive agent. 
     The joint layer member  13  is provided on only the first end closure part  14   c  on the outer panel  5  side of each spring part  12 ; however, the embodiment is not limited thereto. As another example, the joint layer member  13  may be provided on the second end closure part  14   d  on the mass part  11  side of each spring part  12  and may be joined to the mass part  11 . 
     The mass part  11 , the spring part  12 , and the joint layer member  13  that constitute the sound insulation member  10  are joined together and integrated by an adhesive, welding, or the like. 
     As shown in  FIG. 2  and  FIG. 3 , the sound insulation member  10  is provided at a position that avoids a reinforcement frame (roof cross member)  8  provided on the outer panel  5  relative to the outer panel  5  of the vehicle body  1 . In this embodiment, the sound insulation member  10  is formed, between adjacent reinforcement frames  8 , in a band shape that extends longitudinally along the direction in which the reinforcement frame  8  extends. In this way, the sound insulation member  10  can be formed in accordance with the shape of the outer panel  5  or the arrangement of the reinforcement frame  8  or another member provided on the outer panel  5 . The shape of the sound insulation member  10  is not limited to a quadrangular shape, and the sound insulation member  10  can be formed into a triangular shape, a trapezoidal shape, or a variety of other shapes. 
     As shown in  FIG. 6  and  FIG. 7 , the sound insulation member  10  includes the mass part  11  and the spring part  12  and thereby constitutes a sound insulation structure in which the mass part  11  is used as a mass m, and the spring part  12  is used a spring having a spring constant k. In the sound insulation member  10  having such a sound insulation structure, the mass m and the spring constant k are adjusted by adjusting the weight of the mass part  11  and the pressure of the gas  15  encapsulated in the film material  14  constituting the spring part  12 . 
     As described above, the sound insulation member  10  includes the mass part  11  and the spring part  12 , and the spring part  12  is formed by encapsulating the gas  15  within the hollow film material  14 . 
     In this way, the sound insulation member  10  can constitute a sound insulation structure in which the mass part  11  is used as a mass m, and the spring part  12  is used as a spring having a spring constant k. Further, by adjusting the pressure of the gas  15  encapsulated within the film material  14 , it is possible to adjust the spring constant k of the spring part  12 . Furthermore, since the spring part  12  is a configuration in which the gas  15  is encapsulated within the hollow film material  14 , the usage amount of a material that forms the film material  14  is greatly less than that of the urethane layer. Thereby, even if the thickness (that is, the thickness t 1  of the sound insulation member  10 ) of the spring part  12  in a direction in which the mass part  11  and the outer panel  5  face each other is increased in order to enhance a sound insulation property, it is possible to prevent a cost increase and a weight increase of the spring part  12 . 
     Accordingly, it is possible to enhance the sound insulation property while preventing the weight increase and the cost increase. 
     Further, the joint layer member  13  is provided on the side facing the outer panel  5  in the spring part  12 . 
     Thereby, the sound insulation member  10  can be joined by the joint layer member  13  and be attached to the outer panel  5 . 
     Further, by forming the mass part  11  using the polypropylene, it is possible to obtain a high moldability. Further, by forming the film material  14  using the ethylene-vinyl alcohol copolymer, a high airtightness can be obtained, and it is possible to prevent the leakage of the gas  15  encapsulated within the film material  14 . Furthermore, by forming the joint layer member  13  using the polyethylene, the joint layer member  13  can be easily and reliably welded to the outer panel  5 . 
     Further, the specific gravity of the mass part  11  is larger than the specific gravity of the film material  14 . 
     Thereby, the function of the mass part  11  as the mass can be effectively exerted. 
     Further, the Young&#39;s modulus of the film material  14  is smaller than the Young&#39;s modulus of the mass part  11 . 
     Thereby, the spring part  12  is easily deformed elastically, and it is possible to efficiently reduce the noise. 
     Further, the plurality of spring parts  12  are provided to be spaced from each other in the direction along the opposing surface. 
     Thereby, when the spring part  12  is elastically deformed in accordance with the displacement of the mass part  11  so as to approach and be separated from the outer panel  5  side, it is possible to prevent the spring parts  12  adjacent to each other from interfering with each other. Thereby, it is possible to prevent another spring part  12  from blocking the deformation of the spring part  12 , and it is possible to efficiently reduce the noise. 
     Further, air is used as the gas  15  encapsulated in the film material  14 . 
     Thereby, it is possible to reduce costs of the sound insulation member  10 . 
     Further, by using carbon dioxide as the gas  15  encapsulated in the film material  14 , a sonic speed (a propagation speed of sound waves) is reduced compared to a case in the air. Thereby, it is possible to improve the sound insulation performance. 
     Further, by using helium as the gas  15  encapsulated in the film material  14 , the density becomes lower than that of the air. Thereby, it is possible to improve the sound insulation performance 
     Next, the reason for the film material  14  including the recess part  14   b  will be described with reference to  FIG. 6 ,  FIG. 8 , and  FIG. 9 .  FIG. 6  shows the sound insulation member  10  of the embodiment, and  FIG. 8  shows a sound insulation member  100  of a comparison example.  FIG. 9  is a graph showing transmission losses of the sound insulation member  10  and the sound insulation member  100 . In the graph of  FIG. 9 , the vertical axis represents transmission loss (dB) and the horizontal axis represents frequency (Hz). 
     As shown in  FIG. 8 , in the sound insulation member  100  of the comparison example, the spring part  12  of the embodiment is replaced by a spring part  101 , and other configurations are similar to those of the sound insulation member  10 . The spring part  101  includes a hollow film material  102  and a gas  15  encapsulated within the film material  102 . 
     The film material  102  defines a tubular shape that extends in a direction as an axis line in which the mass part  11  and the outer panel  5  face each other. The film material  102  defines a sealed container shape that integrally includes a tubular part  102   a , for example, having a circular cross-sectional shape when seen from the direction in which the mass part  11  and the outer panel  5  face each other, a first end closure part  102   b  that closes an end part on the joint layer member  13  side of the tubular part  102   a , and a second end closure part  102   c  that closes an end part on the mass part  11  side of the tubular part  102   a.    
     That is, the film material  102  of the comparison example only differs from the film material  14  in that the recess part  14   b  is removed from the film material  14  of the embodiment shown in  FIG. 6 , and other configurations are similar to those of the film material  14  of the embodiment. 
     With reference back to  FIG. 8 , the spring part  101  of the comparison example does not include the recess part  14   b  of the embodiment in the film material  102 . Therefore, it is conceivable that the pressure (that is, the internal pressure of the film material  102 ) of the gas  15  encapsulated within the film material  102  is varied in response to, for example, an external environment. It is conceivable that, according to the variation of the pressure of the gas  15 , the spring part  101  is expanded, and for example, a layout space of the spring part  101 , a durability of the spring part  101 , the spring constant, and the like are affected. 
     Hereinafter, transmission losses of the sound insulation member  100  of the comparison example and the sound insulation member  10  of the embodiment will be described with reference to  FIG. 9 . In  FIG. 9 , the graph G 1  shows a transmission loss when the sound insulation member  10  of the embodiment is used in an ordinary-pressure environment. The graph G 2  shows a transmission loss when the sound insulation member  10  of the embodiment is used in a low-pressure environment at a high altitude. The graph G 3  shows a transmission loss when the sound insulation member  100  of the comparison example is used in the low-pressure environment at a high altitude. 
     In the graph G 1  and graph G 2 , the resonance frequency is a frequency H 1 , and in the graph G 3 , the resonance frequency is a frequency H 2 . 
     In the spring part  12  of the sound insulation member  10  of the embodiment, the film material  14  includes the recess part  14   b . Accordingly, by deforming the recess part  14   b  in response to the low-pressure environment at a high altitude, it is possible to prevent the variation of the pressure (that is, the internal pressure of the film material  14 ) of the gas  15 . That is, in a low-pressure environment, the expansion of the spring part  12  can be prevented, and it is possible to ensure that the resonance frequency of the graph G 2  is the same as the resonance frequency H 1  of the graph G 1  (that is, an ordinary-pressure environment). 
     Thereby, as shown in the graph G 1  and the graph G 2 , according to the sound insulation member  10  of the embodiment, it is possible to ensure the transmission loss in the low-pressure environment similarly to the ordinary-pressure environment, and the sound insulation property can be ensured. 
     On the other hand, in the spring part  101  of the comparison example, the film material  102  does not include the recess part  14   b  of the embodiment. 
     Therefore, it is conceivable that the pressure (that is, the internal pressure of the film material  102 ) of the gas  15  encapsulated within the film material  102  is varied in response to the low-pressure environment at a high altitude. Due to the variation of the pressure of the gas  15 , the spring part  101  is expanded, the durability of the spring part  101 , the spring constant, and the like are affected, and the resonance frequency of the graph G 3  is increased to the frequency H 2 . 
     In this way, as shown in the graph G 3 , according to the sound insulation member  100  of the comparison example, in the low-pressure environment at a high altitude, the resonance frequency is increased to the frequency H 2 , and thereby, the transmission loss is reduced. Therefore, it is difficult to ensure the sound insulation property in the low-pressure environment similarly to the ordinary-pressure environment. 
     Hereinafter, first to seventh modified examples of the embodiment will be described with reference to  FIG. 10  to  FIG. 18 . In the first to seventh modified examples, the same reference numerals are given to the same and analogous configurations as those of the embodiment, and detailed description of the configurations is omitted. 
     First Modified Example of Embodiment 
     A first modified example of the embodiment is described with reference to  FIG. 10 . 
     As shown in  FIG. 10 , in a sound insulation member  20 , a spring part  21  is constituted of a film material  22  and a gas  15 . In the film material  22 , the recess part  14   b  of the embodiment is replaced by a recess part  22   a , and other configurations are similar to those of the film material  14  of the embodiment. 
     The recess part  22   a  is formed on the first end closure part  14   c  of the film material  22  to have an annular shape such that the recess part  22   a  is coaxial with respect to the film material  22 . The recess part  22   a  includes a bottom part  22   b  and a side wall  22   c . The side wall  22   c  is formed in a circumferential shape. That is, the recess part  22   a  is formed in a circumferential recess shape. 
     The recess part  22   a  is formed on the first end closure part  14   c  of the film material  22 , and thereby, a cross-sectional area of a region  14   i  that includes the recess part  22   a  is set (adjusted) to be smaller than that of another region  14   j . Thereby, the spring constant of the spring part  21  can be preferably lowered, and the resonance frequency by the sound insulation member  20  can be lowered. 
     Further, the recess part  22   a  is formed to be deformable in response to the pressure of the gas  15  encapsulated within the film material  22 . For example, the recess part  22   a  is formed such that, by deforming a side wall  22   c  in response to the pressure of the gas  15 , a bottom portion  22   b  is movable in an arrow A direction (that is, in the direction in which the mass part  11  and the outer panel  5  face each other). 
     Therefore, by deforming the recess part  22   a , for example, in response to a low-pressure environment at a high altitude or a high-temperature environment, it is possible to prevent the variation of the pressure (that is, the internal pressure of the film material  22 ) of the gas  15 . 
     Thereby, the expansion of the spring part  21  can be prevented, and “preventing the spring part  21  from affecting the layout space”, “ensuring the durability of the spring part  21 ”, and “ensuring the sound insulation property by preventing the increase of the spring constant” can be realized. 
     The side wall  22   c  is formed in a circumferential shape. Therefore, for example, it is possible to smoothly deform the entire region of the recess part  22   a  in response to the low-pressure environment at a high altitude or the high-temperature environment. Thereby, it is possible to favorably prevent the variation of the pressure (that is, the internal pressure of the film material  22 ) of the gas  15 . 
     The first modified example is described using an example in which the recess part  22   a  is formed on the first end closure part  14   c  on the outer panel  5  side; however, the embodiment is not limited thereto. As another example, the recess part  22   a  can be formed on the second end closure part  14   d  on the mass part  11  side. 
     Second Modified Example of Embodiment 
     A second modified example of the embodiment is described with reference to  FIG. 11 . 
     As shown in  FIG. 11 , in a sound insulation member  30 , a spring part  31  is constituted of a film material  32  and a gas  15 . In the film material  32 , the recess part  14   b  of the embodiment is replaced by a first recess part (recess part)  32   a  and a second recess part (recess part)  32   b , and other configurations are similar to those of the film material  14  of the embodiment. 
     The first recess part  32   a  is formed in a circumferential recess shape coaxially with respect to the film material  32  similarly to the recess part  14   b  of the embodiment. The second recess part  32   b  is formed in an annular recess shape (circumferential recess shape) such that the second recess part  32   b  is coaxial with respect to the film material  22  similarly to the recess part  22   a  of the first modified example. 
     The first recess part  32   a  and the second recess part  32   b  are formed on the first end closure part  14   c  of the film material  32 , and thereby, a cross-sectional area of a region  14   i  that includes the first recess part  32   a  and the second recess part  32   b  is set (adjusted) to be smaller than that of another region  14   j . Thereby, the spring constant of the spring part  31  can be preferably lowered, and the resonance frequency by the sound insulation member  30  can be lowered. 
     Further, the first recess part  32   a  and the second recess part  32   b  are formed to be deformable in response to the pressure of the gas  15  encapsulated within the film material  32 . For example, the first recess part  32   a  and the second recess part  32   b  are formed such that, by deforming a side wall in response to the pressure of the gas  15 , a bottom portion is movable in an arrow A direction (that is, in the direction in which the mass part  11  and the outer panel  5  face each other). 
     Therefore, by deforming the first recess part  32   a  and the second recess part  32   b , for example, in response to a low-pressure environment at a high altitude or a high-temperature environment, it is possible to prevent the variation of the pressure (that is, the internal pressure of the film material  32 ) of the gas  15 . 
     Thereby, the expansion of the spring part  31  can be prevented, and “preventing the spring part  31  from affecting the layout space”, “ensuring the durability of the spring part  31 ”, and “ensuring the sound insulation property by preventing the increase of the spring constant” can be realized. 
     The side walls of the first recess part  32   a  and the second recess part  32   b  are formed in a circumferential shape. Therefore, for example, it is possible to smoothly deform the entire region of the first recess part  32   a  and the second recess part  32   b  in response to the low-pressure environment at a high altitude or the high-temperature environment. Thereby, it is possible to favorably prevent the variation of the pressure (that is, the internal pressure of the film material  32 ) of the gas  15 . 
     The second modified example is described using an example in which the first recess part  32   a  and the second recess part  32   b  are formed on the first end closure part  14   c  on the outer panel  5  side; however, the embodiment is not limited thereto. As another example, the first recess part  32   a  and the second recess part  32   b  can be formed on the second end closure part  14   d  on the mass part  11  side. 
     Third Modified Example of Embodiment 
     A third modified example of the embodiment is described with reference to  FIG. 12A  and  FIG. 12B . 
     As shown in  FIG. 12A  and  FIG. 12B , in a sound insulation member  40 , a spring part  41  is constituted of a film material  42  and a gas  15 . The film material  42  defines a sealed container shape that integrally includes a tubular part  42   a , a plurality of protrusion parts  42   b , a first end closure part  42   c , and a second end closure part  42   d . The film material  42  is formed of a material having airtightness and flexibility similarly to the film material  14  of the embodiment. 
     The tubular part  42   a  is formed such that the cross-sectional shape seen from the direction in which the mass part  11  and the outer panel  5  face each other is, for example, a circular tubular shape. The inside of the tubular part  42   a  communicates with the insides of the plurality of protrusion parts  42   b . The plurality of protrusion parts  42   b  radially protrude from an outer circumferential wall  42   e  of the tubular part  42   a  to be spaced from each other in the circumferential direction. Therefore, a plurality of recess parts  42   f  is formed of adjacent protrusion parts  42   b  and the outer circumferential wall  42   e  between the adjacent protrusion parts  42   b  along the outer circumferential wall  42   e.    
     The recess part  42   f  is provided in a state of opening to both sides of the outer panel  5  and the mass part  11 . The number of the plurality of protrusion parts  42   b  (that is, the plurality of recess parts  42   f ) can be arbitrarily selected. 
     In the tubular part  42   a  and the plurality of protrusion parts  42   b , a first end part on the outer panel  5  side is closed by the first end closure part  42   c . The first end closure part  42   c  is integrally joined, for example, to the outer panel  5  by the joint layer member  13  similarly to the first end closure part  14   c  of the embodiment. 
     In the tubular part  42   a  and the plurality of protrusion parts  42   b , a second end part on the mass part  11  side is closed by the second end closure part  42   d . The second end closure part  42   d  is integrally joined, for example, to the mass part  11  by an adhesive, welding, or the like similarly to the second end closure part  14   d  of the embodiment. 
     The recess part  42   f  is formed of the adjacent protrusion parts  42   b  and the outer circumferential wall  42   e  between the adjacent protrusion parts  42   b . Therefore, the recess part  42   f  is formed to be deformable in a shape indicated by an imaginary line of  FIG. 12B  according to the deformation of the protrusion part  42   b  and the outer circumferential wall  42   e  in response to the pressure of the gas  15  encapsulated within the film material  22 . 
     Thereby, for example, it is possible to prevent the variation of the pressure (that is, the internal pressure of the film material  42 ) of the gas  15  by deforming the recess part  42   f  in response to the low-pressure environment at a high altitude or the high-temperature environment. 
     Accordingly, the expansion of the spring part  41  can be prevented, and “preventing the spring part  41  from affecting the layout space”, “ensuring the durability of the spring part  41 ”, and “ensuring the sound insulation property by preventing the increase of the spring constant” can be realized. 
     Fourth Modified Example of Embodiment 
     A fourth modified example of the embodiment is described with reference to  FIG. 13  and  FIG. 14 . 
     In the above-described embodiment, each spring part  12  (refer to  FIG. 6 ) is defined as a circular shape in a cross-section; however, the shape is not limited thereto. For example, as shown in  FIG. 13  and  FIG. 14 , the spring part  12 B may be formed in a substantially rectangular shape having a larger cross-sectional area than the spring part  12  of the above-described embodiment. Thereby, the encapsulation area of the gas  15  of the spring part  12 B can be increased compared to that of the spring part  12  of the embodiment. 
     In this case, the spacing between spring parts  12 B adjacent to each other may be narrower than the spacing between the spring parts  12  in the embodiment. 
     Fifth Modified Example of Embodiment 
     A fifth modified example of the embodiment is described with reference to  FIG. 5 . 
     As shown in  FIG. 15 , the spring part  12 C can be formed in a so-called honeycomb configuration in which the cross-sectional shape is a hexagonal shape, and the spring parts  12 C adjacent to each other are arranged with no clearance gap. By forming the spring part  12 C in the honeycomb configuration, the encapsulation area of the gas  15  of the spring part  12 C can be increased compared to the spring part  12  of the embodiment. 
     Sixth Modified Example of Embodiment 
     A sixth modified example of the embodiment is described with reference to FIG.  16  and  FIG. 17 . 
     In the sound insulation member  10  described above, a hard board material  16  can be added on the joint layer member  13  side as shown in  FIG. 16  and  FIG. 17 . In this case, the board material  16  can be formed of a resin material or the like that is harder than the film material  14 . Such a board material  16  can be provided to be interposed between the spring part  12  and the joint layer member  13 . 
     Seventh Modified Example of Embodiment 
     A seventh modified example of the embodiment is described with reference to  FIG. 18 . 
     As shown in  FIG. 18 , for example, the sound insulation member  10  can be mounted not on the outer panel  5  side but on the inner panel  6  side. In this case, the sound insulation member  10  can be provided such that the joint layer member  13  is joined to the inner panel  6 , and the mass part  11  is located on the outer panel  5  side. 
     The present invention is not limited to the embodiment and the modified examples of the embodiment described with reference to the drawings, and various modified examples are conceivable in the technical scope of the invention. 
     For example, the mass part  11  and the film material  14 ,  22 ,  32 ,  42  may be integrally molded. Thereby, it is not necessary to join the mass part  11  and the film material  14 ,  22 ,  32 ,  42 , and the sound insulation member  10  can be efficiently manufactured. 
     For example, in the embodiment and the modified examples of the embodiment described above, the sound insulation member  10  is provided on the roof part  1 G of the vehicle body  1 ; however, the embodiment is not limited thereto. The sound insulation member  10  may be provided on another region such as the right and left front side doors  1 B, the right and left rear side doors  1 C, the bonnet  1 D, the tail gate  1 E, the right and left quarter panels  1 F, and the roof part  1 G. In the above embodiment, the sound insulation member  10  is provided on the automobile; however, the embodiment is not limited thereto. The sound insulation member  10  may be provided on another structure body such as a ceiling, a wall, and a floor of a building, and a cover of various devices. 
     Although manufacturing and handling are facilitated by the sound insulation structure being constituted of the sound insulation member  10  independent of the vehicle body  1 , a sound insulation structure including the mass part  11  and the spring part  12 ,  12 B,  12 C,  21 ,  31 ,  41  may be provided directly on the compartment member. 
     For example, the embodiment is described using an example in which the recess part  14   b ,  22   a , the first recess part  32   a , and the second recess part  32   b  are formed in a circumferential recess shape; however, these recess parts can be formed in a recess having another shape. 
     The configuration in the above-described embodiment is an example of the present invention, and various changes can made without departing from the scope of the present invention.