Mikuni Adec Corporation

Noriaki Chiba

Kenichi Kubota

Norio Takehana

Hideo Terada

Rui Matuzaka

Kenichi Oikawa

In order to provide a diaphragm type fuel pump which is compact and assures a stable operation, a cavity is formed in a pump body at a position where the pump body is in contact with a fuel discharge chamber. The cavity is arranged between outer and inner parts of the pump body and perpendicularly extends to a diaphragm. The pump body has a return path communicating with a fuel intake chamber and the cavity via opposite ends thereof. A pressure regulating mechanism is housed in the cavity using a cap attached to the pump body, and is positioned inside an outer diameter of a pump chamber. This prevents the pressure regulating chamber from projecting out of the pump chamber contrary to a pressure regulating chamber of the related art, and makes the fuel pump compact. A valve seat is formed in the cap which is separate from the pump body. This facilitates machining of the valve seat.

Diaphragm type fuel pump

A diaphragm is sandwiched between a first body and a second body , and comprises an outer diaphragm which is made of synthetic resin and has an opening formed within an effective diameter X, and an inner diaphragm arranged in the opening . The outer and inner diaphragms and are hermetically sealed by a coupling member made of rubber. Therefore, the diaphragm reciprocates as a synthetic resin diaphragm at very low temperatures. At normal temperatures, the inner diaphragm reciprocates extensively via the rubber coupling member compared with the outer diaphragm , thereby increasing a flow rate of the fuel pump compared with a fuel pump in which a diaphragm is made only of synthetic resin. When the diaphragm is replaced depending upon a desired flow rate, the second body can be manufactured using one die, which is effective in reducing manufacturing costs.

A fuel pump which has excellent heat resistance and salt resistance, is low in cost and light in weight, and which is free from fuel leakage. The fuel pump has a bottom body formed of a thermosetting resin such as bakelite material which has heat resistance and strength, and a top body and a cover formed of a thermoplastic resin. The top body and the cover are assembled with a seal member such as a gasket held between the top body and the cover, and the top body and the bottom body are fixed together by a fixing element. Thereby, the main body portions of the fuel pump are constituted of resin.

Fuel pump

An O-ring shaped annular rib (,) is disposed around the outer periphery of a flexible diaphragm member (,), and grooves (,) are formed in first and second resin members (,) for receiving the annular rib (,) in the compressed state. A hollow space is defined between the first and second members (,) for holding the diaphragm (,) in the clamped state. A contact surface (,) where the first and second synthetic resin members (,) come into contact with each other, is located outward of the grooves (,), and is subjected to welding with a supersonic welding tool (,). A gap (,) is formed between the first synthetic resin member (,) and the supersonic welding tool (,), which gap disappears as the welding progresses. At this time, further progress of the welding operation is inhibited by allowing the first synthetic resin member (,) and the supersonic welding tool (,) to provide a predetermined compression for the annular rib (,). Alternatively, a metallic spacer (,) is interposed between the first synthetic resin member (,) and the second synthetic resin member,with a gap (,) between the second synthetic resin member (,) and the metallic spacer (,) prior to a welding operation, which gap (,) disappears as the welding operation progresses, until further progress of the welding operation is halted.

Growing community of inventors

Morioka, Japan

Noriaki Chiba