A cylinder internal pressure sensor includes: a housing; a diaphragm having flexibility and being joined to one end of the housing; a sensor element configured to change an output signal according to deformation of the diaphragm; and an opposed member housed inside the housing so as to face the diaphragm. The opposed member defines a housing room between the diaphragm and the opposed member, and includes: a cylindrical tube part being a layered structure with an inner tube and an outer tube; and a seal part provided inside the tube part. The sensor element is fixed to the seal part. The tube part is provided with a spring rate reducing portion that is provided between the diaphragm and a position where the inner tube and the outer tube are joined together.

A cylinder internal pressure sensor includes: a housing; a diaphragm having flexibility and being joined to one end of the housing; a sensor element configured to change an output signal according to deformation of the diaphragm; and an opposed member housed inside the housing so as to face the diaphragm. The opposed member defines a housing room between the diaphragm and the opposed member, and includes: a cylindrical tube part being a layered structure with an inner tube and an outer tube; and a seal part provided inside the tube part. The sensor element is fixed to the seal part. The tube part is provided with a spring rate reducing portion that is provided between the diaphragm and a position where the inner tube and the outer tube are joined together.

An integrated fault monitoring apparatus for electrical devices has an internal fault detector for detecting transient pressure surges within the electrical device, a pressure relief valve for allowing release of pressure during normal operating conditions of the electrical device, a temperature indicator for indicating that an operating temperature of the electrical device has gone above a predetermined threshold, and/or a sudden pressure relief device for allowing air to escape from the electrical device in the event of a sudden and significant increase in pressure within the electrical device. Methods of using the apparatus are provided.

An integrated fault monitoring apparatus for electrical devices has an internal fault detector for detecting transient pressure surges within the electrical device, a pressure relief valve for allowing release of pressure during normal operating conditions of the electrical device, a temperature indicator for indicating that an operating temperature of the electrical device has gone above a predetermined threshold, and/or a sudden pressure relief device for allowing air to escape from the electrical device in the event of a sudden and significant increase in pressure within the electrical device. Methods of using the apparatus are provided.

A cylinder internal pressure sensor includes: a housing; a diaphragm having flexibility and being joined to one end of the housing; a sensor element configured to change an output signal according to deformation of the diaphragm; and an opposed member housed inside the housing so as to face the diaphragm. The opposed member defines a housing room between the diaphragm and the opposed member, and includes: a cylindrical tube part being a layered structure with an inner tube and an outer tube; and a seal part provided inside the tube part. The sensor element is fixed to the seal part. The tube part is provided with a spring rate reducing portion that is provided between the diaphragm and a position where the inner tube and the outer tube are joined together.

A cylinder internal pressure sensor includes: a housing; a diaphragm having flexibility and being joined to one end of the housing; a sensor element configured to change an output signal according to deformation of the diaphragm; and an opposed member housed inside the housing so as to face the diaphragm. The opposed member defines a housing room between the diaphragm and the opposed member, and includes: a cylindrical tube part being a layered structure with an inner tube and an outer tube; and a seal part provided inside the tube part. The sensor element is fixed to the seal part. The tube part is provided with a spring rate reducing portion that is provided between the diaphragm and a position where the inner tube and the outer tube are joined together.