Denso Corporation

Nippondenso Co., Ltd.

Kenji Funai

Masatoshi Kuroyanagi

Ryo Katsura

Toshihiko Igashira

Masaaki Kato

Akira Shibata

Satoshi Hayashi

Kenji Date

Yutaka Yamada

Makoto Mashida

Yasuhiro Kariya

Ken Mizutani

A fuel injector injects high-pressure gaseous fuel directly into a cylinder of an engine. A small amount of liquid fuel is used in the injector to lubricate sliding portions of the fuel injector in addition to utilizing it as a medium for transmitting driving force. The fuel injector includes a nozzle member having injection holes at its elongated end and a needle slidably disposed in an elongated center hole of the nozzle member. The needle is driven by pressure of the liquid fuel introduced into a control chamber to open or close the injection holes. The pressure in the control chamber is controlled by a switching valve which is in turn driven by an actuator such as an electromagnetic or piezoelectric actuator. The liquid fuel is injected together with the high-pressure gaseous fuel after lubricating the sliding portions between the nozzle member and the needle.

Gaseous fuel injector using liquid fuel as lubricant and pressure-transmitting medium

A valve back pressure chamber is provided to exert a back pressure of a first valve needle. Furthermore, a hydraulic pressure passage is provided to extend through the valve back pressure chamber. A valve body is provided to a second valve needle and is driven to connect and disconnect between the hydraulic pressure passage and a fuel tank and thereby to drive the first valve needle. The second valve needle is driven by hydraulic pressure induced by an actuator.

Injector having structure for controlling nozzle needle

A fuel injector for an internal combustion engine is provided. The fuel injector has a simple structure so that it is easy to install and remove a piezoelectric valve actuator in and from the fuel injector, and to adjust fuel injection characteristics finely which allows the overall size of the fuel injector to be decreased. The fuel injector includes a housing to be installed in the engine and a structural element serving to install the piezoelectric valve actuator in the housing to be detachable easily. The piezoelectric valve actuator is retained in an actuator casing fitted in the housing so that it can expand or contract to move a needle valve. The actuator casing has an extensible portion in itself or is coupled to a bellows in alignment for enabling the piezoelectric valve actuator to expand, thereby allowing the size of the actuator casing to be minimized.

Structure of fuel injector using piezoelectric actuator

A fuel injector is provided which is designed to suppress unwanted vibrations of a nozzle needle-actuating piston, thereby avoiding the injection of an excess quantity of fuel. The fuel injector comprises an actuator and a displacement amplifying chamber filled with fluid to which a large-diameter piston and a small-diameter piston working as the nozzle needle-actuating piston are exposed. The displacement amplifying chamber works to amplify and transmit displacement of the large-diameter piston by the actuator to the small-diameter piston. The fuel injector also includes a stopper which restricts movement of the small-diameter piston toward the displacement amplifying chamber to a given range, thereby suppressing the unwanted vibrations of the small-diameter piston.

Structure of fuel injector for avoiding injection of excess quantity of fuel

A safety valve provided in a fuel injection apparatus includes an accumulator in which fuel is accumulated. The housing has an inside passage for introducing high-pressure fuel of the accumulator into the inside of the housing and a seat face formed at a portion of the inside passage. A valve element provided movably within the housing includes a valve body to open/close the seat face and an elastic member for pressing and biasing the valve element in a closing direction. A fuel chamber defined between the inner surface of the housing and the valve element maintains pressure for pressing the valve element in a valve-opening direction, and high pressure fuel from the inside passage is introduced into the fuel chamber when the valve body of the valve element is separated from the seat face. With this safety valve, the high-pressure fuel of the accumulator is introduced into the fuel chamber in order to press the valve element in the valve-opening direction so that the valve element will be rapidly opened, with the result that the fuel pressure in the accumulator can recover a predetermined value instantaneously.

Growing community of inventors

Kariya, Japan

Kenji Funai