Fuel cap

Abstract

For transmission of rotative operation on a lid body to a cap body, a transmission mechanism for mechanically coupling the lid body and the cap body transmits the rotative operation on the lid body to the cap body. If a pressure difference determined across a seal plate between a pressure in an inlet and a pressure outside the inlet becomes a predetermined pressure or more, the seal plate makes irreversible shape change. The irreversible shape change of the seal plate releases the transmission mechanism from the mechanical coupling to at least one of the lid body and the cap body, thereby cutting transmission of the rotative operation on the lid body to the cap body. Thus, a fuel cap to be provided is capable of notifying the occurrence of abnormality in a fuel system as physical feeling during operation on the fuel cap.

What is claimed is: 
     
         1 . A fuel cap comprising:
 an annular cap body fitted to an inlet for fuel to be supplied to a fuel tank and fitted in an airtight state to the inlet;   a lid body to receive rotative operation by a user for attachment and removal of the cap body to and from the inlet;   a transmission mechanism mechanically coupled to the lid body and the cap body to transmit the rotative operation on the lid body to the cap body; and   a seal plate provided in the cap body, the seal plate making irreversible shape change when a pressure difference between an internal pressure in the inlet in the airtight state and an external pressure outside the inlet exceeds a predetermined pressure difference to establish communication between the inlet and the atmosphere, wherein   the irreversible shape change of the seal plate releases the transmission mechanism from the mechanical coupling to at least one of the lid body and the cap body.   
     
     
         2 . The fuel cap in accordance with  claim 1 , wherein
 the seal plate includes a thin part to break as the irreversible shape change, a channel inner region plate part in a range of a smaller area than an opening region of the cap body, and a channel outer region plate part surrounding the channel inner region plate part, the thin part defining channel inner region plate part and the channel outer region plate part, and   the transmission mechanism includes:   a transmission piece member provided at the seal plate while extending from the channel inner region plate part to the channel outer region plate part so as to cover the thin part;   a channel outer restricting member projecting from an inner peripheral wall of the cap body and functioning to form the mechanical coupling by restricting the transmission piece member around the axis of the cap body at the channel outer region plate part; and   a channel inner restricting member drooping from the lid body toward the seal plate and functioning to form the mechanical coupling by restricting the transmission piece member around the axis of the cap body at the channel inner region plate part.   
     
     
         3 . The fuel cap in accordance with  claim 2 , further comprising:
 a spring that applies biasing force to the channel inner region plate part of the seal plate, wherein   the thin part of the seal plate has a strength that does not break the thin part under a condition that the channel inner region plate part receives the biasing force from the spring while the pressure difference does not reach the predetermined pressure difference,   a positive-pressure difference and a negative-pressure difference have a differential, the positive-pressure difference is the predetermined pressure difference on the occurrence of a positive pressure determined when the internal pressure is higher than the external pressure, the negative-pressure difference is the predetermined pressure difference on the occurrence of a negative pressure determined when the internal pressure is lower than the external pressure, and   the spring is arranged in such a manner that the channel inner region plate part receives the biasing force to suppress the differential of the pressure difference that makes the irreversible shape change of the seal plate on the occurrence of the positive pressure and the negative pressure.   
     
     
         4 . The fuel cap in accordance with  claim 3 , wherein
 the lid body includes an engagement part adjacent to the cap body and becomes deformable in response to receipt of depression toward the cap body, and   the cap body includes an engagement target part to be engaged with the engagement part if the lid body deforms in response to receipt of the depression toward the cap body.   
     
     
         5 . The fuel cap in accordance with  claim 4 , wherein
 the cap body includes a ventilation member having gas permeability provided in the opening region of the cap body to be downstream from the seal plate.   
     
     
         6 . The fuel cap in accordance with  claim 4 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         7 . The fuel cap in accordance with  claim 4 , wherein
 the lid body includes a torque plate for defining an operation torque to be applied during the rotative operation, and   the torque plate includes the engagement part and the channel inner restricting member.   
     
     
         8 . The fuel cap in accordance with  claim 3 , wherein
 the cap body includes a ventilation member having gas permeability provided in the opening region of the cap body to be downstream from the seal plate.   
     
     
         9 . The fuel cap in accordance with  claim 8 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         10 . The fuel cap in accordance with  claim 3 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         11 . The fuel cap in accordance with  claim 2 , wherein
 the lid body includes an engagement part adjacent to the cap body and becomes deformable in response to receipt of depression toward the cap body, and   the cap body includes an engagement target part to be engaged with the engagement part if the lid body deforms in response to receipt of the depression toward the cap body.   
     
     
         12 . The fuel cap in accordance with  claim 11 , wherein
 the cap body includes a ventilation member having gas permeability provided in the opening region of the cap body to be downstream from the seal plate.   
     
     
         13 . The fuel cap in accordance with  claim 12 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         14 . The fuel cap in accordance with  claim 11 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         15 . The fuel cap in accordance with  claim 11 , wherein
 the lid body includes a torque plate for defining an operation torque to be applied during the rotative operation, and   the torque plate includes the engagement part and the channel inner restricting member.   
     
     
         16 . The fuel cap in accordance with  claim 2 , wherein
 the cap body includes a ventilation member having gas permeability provided in the opening region of the cap body to be downstream from the seal plate.   
     
     
         17 . The fuel cap in accordance with  claim 16 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         18 . The fuel cap in accordance with  claim 2 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         19 . The fuel cap in accordance with  claim 1 , wherein
 the seal plate is provided to the cap body through a seal member.   
     
     
         20 . The fuel cap in accordance with  claim 1 , further comprising:
 a spring that applies biasing force to the seal plate.