Permeable member, and permeable casing and electrical component using the same

#The present invention relates to a permeable member that is fixed to a casing of an electrical component or the like, ensures ventilation between the inside and outside of the casing and prevents the foreign objects from intruding into the casing, and relates to a permeable casing and an electrical component to which the permeable member is fixed.

#Conventionally, a permeable member is attached to electrical components for a vehicle, such as a lamp, pressure sensor and ECU (Electrical Control Unit), and to casings of electric appliances, such as a mobile-phone and camera. The permeable member ensures ventilation between the inside and outside of the casing and prevents the foreign objects from intruding into the casing. Attaching the permeable member to the casing enables a pressure change inside of the casing accompanying a temperature change to be alleviated, sounds to be transmitted between the inside and outside of the casing and a gas generated in the casing to be discharged to outside, while preventing water, dust and the like from intruding into the casing.

#One example of such a permeable member is disclosed in JP2001-143524A. The permeable member 101 disclosed in JP2001-143524A is provided with a tubular support 103 wherein a permeable film 102 is arranged on its end face and with a protective cover 104 that has a bottom and is fitted into the support 103 so that the protective cover 104 covers the permeable film 102, as shown in FIG. 20. The permeable member 101 is fixed to a casing 105 so as to cover an opening 106 of the casing 105. In this case, when using the support 103 that has a smaller inside diameter than an outside diameter of the opening 106, the permeable member 101 can be fixed to the casing 105 using an elastic force generated by extension of the support 103. In this publication, an elastomer is exemplified as a material for the support 103.

#FIG. 1 is a perspective view showing one example of the permeable member of the present invention in a simplified manner.

#FIG. 2 is a sectional view showing a transverse section of the support of the permeable member of FIG. 1 in a simplified manner.

#FIG. 3 is a sectional view showing one example of the support of the permeable member of the present invention in a simplified manner.

#Hereinafter embodiments of the present invention will be described in reference to the drawings. In the following description, the same numerals will be used for the same members, and repeated explanations thereof will be omitted in some case.

#One example of the permeable member of the present invention is shown in FIG. 1. The permeable member 1 shown in FIG. 1 is provided with a permeable film 3 and a tubular support 2 that supports the permeable film 3. The support 2 is fixed to an opening 52 of a casing 51 so as to cover the opening 52. As shown in FIG. 2, the support 2 is provided with a first resin part 4 that contacts the opening 52 of the casing 51 with the support 2 fixed to the opening 52, and a second resin part 5 composed of a material having a higher elastic modulus than that of a material constituting the first resin part 4. The first resin part 4 and the second resin part 5 are laminated along the whole circumference in a transverse section of the support 2. FIG. 2 is a sectional view showing a transverse section of the support 2 shown in FIG. 1, and “transverse section” means a plane formed by cutting the support 2 with a plane perpendicular to a central axis of the support 2.

#In the permeable member 1, the first resin part 4, which is composed of a resin material A having a relatively small elastic modulus, is arranged on a contact portion of the support 2. The support 2 is in contact with the casing 51 on the contact portion. Therefore, a reduction in the ability of the support 2 to follow the surface (fixing surface) of the casing 51 on which the permeable member 1 is fixed can be inhibited, and the sealing property of the permeable member 1 can be ensured. A decrease in the waterproof property and dust resistance of the casing 51 can be inhibited as well. In addition, in the permeable member 1, the support 2 is composed of a resin material B having a relatively high elastic modulus along with the resin material A. Therefore, the elastic force of the support 2 is increased compared to the case where a support is composed of only a resin material having a small elastic modulus, and thereby the pullout strength of the support 2 can be ensured. Ensuring the pullout strength enables prevention of the permeable member from dropping off the casing. As described above, a permeable member having both the pullout strength and following property (sealing property) can be constituted without thickening the radial thickness of the support 2 or reducing a ratio of the inside diameter of the support 2 relative to the outside diameter of the opening 52. Further, regarding the permeable member 1, the deformation amount of the support 2 when the support 2 is fixed to the casing 51 can be reduced, and therefore the deformation of the permeable film 3 can be inhibited.