Denso Corporation

Eiji Itoh

Shinsuke Yamamoto

Tomoji Matsukawa

Shinobu Oikawa

Keita Imai

Moriyasu Gotoh

Kouichi Mochizuki

Hiroaki Nagatomo

Hiroshi Inoue

Eiji Mimura

Keigo Oohata

Hideaki Ukai

A fuel injection valve includes: a circular plate portion that is abuttable against an end surface of a needle opposite from a valve seat while the needle being provided to open and close an injection hole upon lifting and seating of the needle relative to the valve seat; and a tubular portion that extends from the circular plate portion toward the valve seat and has an end part, which is opposite from the circular plate portion and is abuttable against a movable core second contact surface of a movable core opposite from the valve seat. In a state where the circular plate portion abuts against the needle, and the tubular portion abuts against the movable core, a gap is formed between a flange member end surface of a flange of the needle and a movable core first contact surface of the movable core opposite from the valve seat.

Fuel injection valve

A gap forming member has: a plate portion that is placed on an opposite side of a needle, which is opposite from a valve seat; and an extending portion that is formed to extend from the plate portion toward the valve seat, while an opposite end part of the extending portion, which is opposite from the plate portion, is contactable with a movable core. A first wall surface of the gap forming member, which is a wall surface opposed to an outer wall of the flange, is slidable relative to the outer wall of the flange, and a second wall surface of the gap forming member, which is a wall surface opposed to an inner wall of a stationary core, forms a radial gap, which is a gap in a radial direction, between the second wall surface and the inner wall of the stationary core.

Fuel injection device

An inner side wall surface of a gap forming member, which is opposed to a flange outer wall surface of a flange of a needle, is slidable relative to the flange outer wall surface. Also, an outer side wall surface of the gap forming member, which is opposed to a stationary core inner wall surface of a stationary core, is slidable relative to the stationary core inner wall surface. The flange outer wall surface and the outer side wall surface are curved to project in a radially outer direction of a housing in a cross section thereof taken along an imaginary plane, which includes an axis of the housing.

A current control unit in a fuel injection device controls a magnitude of a current flowing through a coil during single energization. A current Ipflows once a signal input to the current control unit is turned ON at time t. As a result, a movable core and a needle abut against each other with a lift amount increased at time t, and then the needle is separated from a valve seat and pre-injection is performed. At time t, which follows the pre-injection, the needle and movable core lift amount becomes a lift amount Dat a time when the needle and the valve seat abut against each other, and temporary valve closing occurs. At time t, which follows time t, currents Ixand Imlarger than the current Ipare caused to flow through the coil, and then main injection is performed with the needle and movable core lift amount turned into a lift amount Dlarger than the lift amount D. Therefore, fuel injection can be performed twice during the single energization.

A movable core is movable relative to a needle main body of a needle. A stationary core is placed on an opposite side of the movable core, which is opposite from a valve seat. A spring is operable to urge the needle and the movable core toward the valve seat. A spring seat is shaped into a ring form and is placed on a radially outer side of the needle main body at the valve seat side of the movable core. The spring is placed between the movable core and the spring seat and is operable to urge the movable core toward the stationary core. A guide is placed on the valve seat side of the movable core in an inside of a housing. An outer wall of the spring seat is slidable relative to an inner wall of the guide to guide reciprocation of the needle.

A fuel injection control device is adapted for a fuel injection system including an injector and a high-pressure pump that raises pressure of fuel and supplies the fuel to the injector. The fuel injection control device includes a selecting unit for selecting by which one of full lift injection and partial injection to inject fuel, and a pump control unit for controlling operation of the high-pressure pump such that a pressure of fuel supplied to the injector coincides with a target pressure. The selecting unit selects the partial injection when a required injection quantity of fuel is equal to or smaller than a partial maximum injection quantity. A fuel injection system includes the fuel injection control device, the injector, and the high-pressure pump.

Fuel injection control device and fuel injection system

A fuel injection valve includes a housing having a nozzle hole, a valve seat, and a fuel passage; a needle that is accommodated in the housing to be capable of reciprocating in an axial direction of the housing and that opens or closes the nozzle hole; a coil; a fixed core; a movable core; a shift permitting member that is provided between the housing and an internal-combustion engine to permit a shift of an attachment position at time of attachment of the housing and the engine; and a friction reducing part that is provided between the engine and the shift permitting member to reduce friction between the engine and the shift permitting member. The friction reducing part permits displacement of the housing in a direction perpendicular to the axial direction of the housing.

A high-pressure pump includes a plunger, a cylinder, a pressuring chamber, a pump body, a main fuel chamber, an auxiliary fuel chamber and a return passage. The cylinder slidably houses the plunger therein. The pump body houses the cylinder and has an end surface on an opposite side of the pump body relative to the pressurizing chamber in an axial direction. The main fuel chamber is in the pump body. The auxiliary fuel chamber has a side defined by one end of the cylinder on an opposite side of the cylinder relative to the pressurizing chamber. The return passage is inside the pump body and is in fluid communication with an external cooling unit. Fuel leaking out from the pressurizing chamber through a clearance between the cylinder and the plunger is collected inside the auxiliary fuel chamber, and the collected fuel flows toward the external cooling unit through the return passage.

High-pressure pump

A fuel injection valve is attached to an engine and to have an annular seal material attached thereon. The seal material is attached to a first reduced diameter part. In a use state where a body is inserted in an attachment hole formed at a predetermined position of the engine and a gas pressure that is equal to or higher than a predetermined pressure is applied to the seal material from its nozzle hole-side, the seal material is pressed against a first tapered part by the gas pressure to be compressively deformed, and a clearance between an inner peripheral surface of the attachment hole and an outer peripheral surface of the body is sealed with a compressively-deformed part of the seal material. A taper angle of the first tapered part is set in a range from 10 degrees to 20 degrees.

A stationary core includes a holding hole that receives and holds a portion of the magnetic spring, which is located on a valve opening side. A solenoid device includes a magnetic yoke that extends in an axial direction and has an axial extent, which overlaps with an entire axial extent of the holding hole. The magnetic yoke has a predetermined portion, which reduces an amount of the magnetic flux that passes through the magnetic yoke in a radial direction in comparison to the rest of the magnetic yoke.

Fuel injection valve for internal combustion engine

A fuel injector includes a valve body moved together with a movable core and opening an injection port, and an elastic-force applying portion being elastically deformable according to a movement of the valve body to apply an elastic force to the valve body in a valve-closing direction. An elastic coefficient of the elastic-force applying portion is set to meet a condition that Ffc&#x2212;Ffo&#x2266;L&#xd7;K. In this case, a fuel-pressure valve-closing force of when the valve body is closed is referred to as Ffc, and the fuel-pressure valve-closing force of when the valve body is completely opened is referred to as Ffo. A movement distance of the valve body from a time point that the valve body is closed to a time point that the valve body is completely opened is referred to as L. The elastic coefficient is referred to as K.

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Kariya, Japan

Eiji Itoh