Patent ID: 9610839
Date: 2017-04-04
CPC Classifications: B60K

Claim:
1. A filler cap for a fuel tank, wherein the filler cap is attached to a filler opening of the fuel tank, and arranged with an air passage channel to connect between inside and outside the fuel tank in a cap main body comprised of an outer cap and an inner cap and with a valve mechanism portion in the air passage channel; wherein, the valve mechanism portion comprises: a cylinder main body arranged with a first space of a columnar shape arranged almost at a center position of an inner plane of the inner cap so as to be connected to inside the fuel tank, a second space of a columnar shape having a smaller diameter than the first space and arranged so as to be connected to the first space, and a third space arranged so as to be connected to the second space and at the same time to outside the fuel tank, a valve-body-supporting member having a hollow cylindrical form provided with an upper plane and also a lower plane open, and provided with a large diameter portion arranged in the first space so as to form a space connected to inside the fuel tank and a small diameter portion having a smaller outer diameter than the large diameter portion and arranged in the second space with a first air passage channel constituting a part of the air passage channel and connected to the space formed on an upper plane, a valve body formed of a non-air-permeable, elastic material having a thin form with elasticity and flexibility, and also having a circular plain view with a larger diameter than the small diameter portion of the valve-body-supporting member, wherein the valve body is put on the small diameter portion, a central part of the valve body is facing to the third space, and an urging body arranged in the space of the large diameter portion of the valve-body-supporting member and urging a ring-shaped peripheral part of the valve body put on the small diameter portion so as to be pressed onto a stepped surface between a wall surface forming the second space and a wall surface forming the third surface of the cylinder main body by pushing-up the valve-body supporting-member; wherein, in the state in which the peripheral part of the valve body on the valve-body-supporting member is pressed onto the stepped surface by the urging body, when a pressure inside the fuel tank is increased by a vaporized gas evaporated from a fuel in the fuel tank to a pressure for a deformation strength prescribed to the valve body or more, the central part of the valve body moves upward and enters into the third space thereby causing deformation so as to shorten the outer diameter of the valve body to form wrinkles, and as a result, in the peripheral part of the valve body are formed a portion contacting to a pivot of the cylinder main body when the central part of the valve body enters into the third space thereby causing deformation and a concave portion not contacting thereto, and consequently, the second space and the third space are connected via a space of this concave portion and a second air passage channel constituting a part of the air passage channel and formed in the wall surface forming the third space to release an excessive pressure to outside the fuel tank thereby bringing the pressure inside the fuel tank to lower than the pressure for the deformation strength, and in the state in which the peripheral part of the valve body on the valve-body-supporting member is pressed onto the stepped surface by the urging body, when the pressure inside this fuel tank becomes negative at a prescribed value by consumption of the fuel inside the fuel tank, the valve body and the valve-body-supporting member are lowered against the urging force of the urging body by this negative pressure, and at the same time, the peripheral part of the valve body hangs down by using a top part of a chamfered portion chamfered so that the peripheral part of the valve body is sucked toward the fuel tank and a peripheral part on the upper plane of the small diameter portion of the valve-body-supporting member becomes a small diameter upward as a pivot so as to connect between the second space and the third space via a gap between this valve body and the wall surface forming the third space of the cylinder main body as well as the stepped surface thereby introducing an atmospheric air into the fuel tank so as to bring the state of an atmospheric pressure; whereby functioning as a safety valve as well as a one-way valve.