Gas impermeable expansion diaphragm

Claim 2

The combination, comprising means having a unit elastic limit for enclosing and sealing an open end of a housing, said housing having a compartment therein filled with a liquid capable of transmitting pressure waves which strike said housing; said means being substantially parallel with a surface of said housing and responsive to changes in unit volume of said liquid; and said means being substantially impervious to the passage of gaseous elements, said means having a first, second and third layers, said first and third layer having a given unit elastic limit and said second layer having a lower unit elastic limit, said second layer being formed from a metallic substance, said matellic substance being gas impervious, and a layer of fabric positioned between said second layer and at least one of said first and third layers.

Claim 3

The combination in accordance with claim 1 wherein said second layer is formed from lead.

Claim 4

The combination in accordance with claim 2 wherein said first and third layers are formed from an elastomer.

Claim 5

A pressure compensated hydrophone assembly for detecting underwater pressure waves, comprising; a housing having a compartment therein and an opening at one end; at least one sensing unit mounted within said compartment, said sensing unit responsive to said underwater pressure waves; a unit volume of liquid filling said compartment and voids within said sensing unit, said liquid capable of transmitting pressure waves which strike said housing; and a resilient means across said opening of said housing, said resilient means responsive to changes in the unit volume of said liquid and substantially impervious to gaseous elements, said resilient means comprises a first, second, and third layers, said first and third layers having a given unit elastic limit, said first and third layers being formed from an elastomer, said second layer having a lower elastic unit, said second layer being formed from a non-magnetizable metal, said second layer being substantiaLly gas impervious, and a layer of fabric positioned between said second layer and at least one of said first and third layers, said fabric providing means for gasses to escape when said first, second and third layers are molded thereby preserving the integrity of said second layer.

Claim 6

A pressure compensated hydrophone assembly for detecting underwater pressure waves, comprising; a housing having a compartment therein and an opening at one end; at least one sensing unit mounted within said compartment, said sensing unit responsive to said underwater pressure waves; a unit volume of liquid filling said compartment and voids within said sensing unit, said liquid capable of transmitting pressure waves which strike said housing; and a resilient means across said opening of said housing, said resilient means responsive to changes in the unit volume of said liquid and substantially impervious to gaseous elements, said resilient means comprises a first, second, and third layers, said first and third layers having a given unit elastic limit, said first and third layers being formed from an elastomer, said second layer having a lower elastic unit, said second layer being formed from a non-magnetizable metal, said second layer being substantiaLly gas impervious, and a layer of fabric positioned between said second layer and at least one of said first and third layers, said fabric providing means for gasses to escape when said first, second and third layers are molded thereby preserving the integrity of said second layer.

Claim 7

Apparatus in combination with claim 4 wherein said second layer is formed from lead.

Claim 8

Apparatus in combination with claim 4 wherein said liquid is free from all gasses.

Claim 9

Apparatus for detecting the presence of underwater pressure waves, comprising a hydrophone assembly for generating signals in response to incident pressure waves, said hydrophone comprising a housing having a cavity therein and open at one end thereof; a sensing unit mounted within said cavity, said sensing unit responsive to said underwater pressure waves and arranged to generate a corresponding electrical signal; a unit volume of liquid filling said cavity and voids within said sensing unit; and a diaphragm assembly across said opening, said diaphragm responsive to changes in the unit volume of said liquid and substantially impervious to the passage of gaseous elements, said diaphragm assembly comprising a first and third layer of resilient material having a given unit elastic limit, and a second layer of metallic substance having a lower elastic limit positioned between said first and third layers, said second layer being formed from lead and being substantially gas impervious, and a layer of fabric being positioned between said second layer and at least one of said first and third layers to preserve the integrity of said second layer when said first, second and third layers are assembled into an integral unit; and means for maintaining said hydrophone assembly in position in the region of the underwater waves.

Claim 10

Apparatus for detecting the presence of underwater pressure waves, comprising a hydrophone assembly for generating signals in response to incident pressure waves, said hydrophone comprising a housing having a cavity therein and open at one end thereof; a sensing unit mounted within said cavity, said sensing unit responsive to said underwater pressure waves and arranged to generate a corresponding electrical signal; a unit volume of liquid filling said cavity and voids within said sensing unit; and a diaphragm assembly across said opening, said diaphragm responsive to changes in the unit volume of said liquid and substantially impervious to the passage of gaseous elements, said diaphragm assembly comprising a first and third layer of resilient material having a given unit elastic limit, and a second layer of metallic substance having a lower elastic limit positioned between said first and third layers, said second layer being formed from lead and being substantially gas impervious, and a layer of fabric being positioned between said second layer and at least one of said first and third layers to preserve the integrity of said second layer when said first, second and third layers are assembled into an integral unit; and means for maintaining said hydrophone assembly in position in the region of the underwater waves.

Claim 11

Apparatus in accordance with claim 7, wherein said first and third layers of said diaphragm are form from an elastomer.