Abstract: In a motorcar having a compressed fuel cylinder charged with a compressed fuel disposed in a compartment, pipes connected to the fuel cylinder within the compartment are connected to a joint unit penetrating a partition wall partitioning the compartment from an outside and the joint unit is connected to pipes connected to an internal combustion engine and the like out of the compartment. A fuel charge passage, a fuel supply passage and a relief passage in a cylinder cap of the fuel cylinder and a fuel charge passage, a fuel supply passage and a relief passage in an interior side of the joint unit are connected with each other through an interior charge pipe, and interior supply pipe and an interior fuel relief pipe, respectively. A fuel charge pipe, a fuel supply pipe and a relief pipe out of the compartment are connected to a fuel charge passage, a fuel supply passage and a relief passage in an exterior side of the joint unit.

Abstract: A compressed natural gas charging system includes a gas charging passageway whose one end is capable of being connected to a compressed natural gas supply device capable of supplying a compressed natural gas and whose other end opens into a gas vessel, and a one-way valve incorporated in the gas charging passageway to permit the compressed natural gas to flow from the one end of the gas charging passage through the one-way valve toward the other end. In the compressed natural gas charging system, a constriction is provided in the gas charging passageway downstream of the one-way valve and has a constriction degree larger than that of the one-way valve. Thus, it is possible to prevent an excessive temperature drop due to the adiabatic expansion of the compressed natural gas from occurring across the one-way valve and to rapidly charge the compressed natural gas, and it is unnecessary to use an expensive material for a part of or constituting the one-way valve.