Fuel injection valve for internal combustion engine

Patent metadata

Field	Value
Publication number	US-9334842-B2
Application number	US-201314140693-A
Country	US
Kind code	B2
Filing date	Dec 26, 2013
Priority date	Dec 26, 2012
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

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.

First claim

What is claimed is:

1. A fuel injection valve for an internal combustion engine, comprising:
a valve housing that includes an injection hole, which is configured to inject fuel in the internal combustion engine;
a valve member that is configured to reciprocate between a valve opening side and a valve closing side, which are opposite to each other in an axial direction, to respectively open and close the injection hole;
a stationary core that is fixed to the valve housing;
a movable core that is movable together with the valve member, wherein the movable core moves toward the valve opening side when a magnetic force is exerted between the stationary core and the movable core;
a magnetic spring that is a coil spring that is made of a magnetic material, wherein the magnetic spring is held by the stationary core and urges the valve member toward the valve closing side; and
a solenoid device that is held on a radially outer side of the stationary core and generates the magnetic force by guiding a magnetic flux to the stationary core and the movable core in response to energization of the solenoid device, wherein:
the stationary core includes:
a holding hole that receives and holds a wound end portion of the magnetic spring, wherein the wound end portion is fitted into the holding hole and has a predetermined number of turns from an axial end of the magnetic spring, which is located on the valve opening side; and
a loosely receiving hole that is axially placed adjacent to the holding hole on the valve closing side and loosely receives a loosely received portion of the magnetic spring, which is placed adjacent to the wound end portion on the valve closing side, wherein an inner diameter of the loosely receiving hole is larger than an inner diameter of the holding hole;
the solenoid device includes a magnetic yoke that extends in the axial direction and has an axial extent, which overlaps with an entire axial extent of the holding hole, wherein the magnetic yoke has a predetermined portion that is located only in a single circumferential location along a circumferential extent of the magnetic yoke and reduces an amount of the magnetic flux, which passes through the magnetic yoke in a radial direction, in comparison to the rest of the circumferential extent of the magnetic yoke, which is other than the single circumferential location; and
an axial extent of the predetermined portion of the magnetic yoke overlaps with the entire axial extent of the holding hole and an entire axial extent of the wound end portion of the magnetic spring received in the holding hole; and
when the solenoid device is energized, the wound end portion of the magnetic spring is urged against a portion of an inner peripheral wall of the holding hole, which is radially opposite from the single circumferential location where the predetermined portion is placed.

2. The fuel injection valve according to claim 1 , wherein a portion of the magnetic yoke is configured into a partially cut ring form, which opens in the predetermined portion.

3. The fuel injection valve according to claim 1 , wherein the valve member is movable relative to the movable core.

4. The fuel injection valve according to claim 1 , wherein:
the valve member includes a shaft portion, which extends in the axial direction, and a projection, which radially outwardly projects from the shaft portion;
the shaft portion extends through the movable core and is movable relative to the movable core;
when the movable core is moved toward the stationary core and contacts the projection at an axial end surface of the movable core located on the valve opening side, the movable core moves together with the valve member;
when the movable core is moved to a moving end of the movable core on the valve opening side, the movable core contacts the stationary core and is stopped by the stationary core;
the magnetic spring is a valve-closing spring, which is interposed between the stationary core and the valve member; and
the fuel injection valve further includes a valve-opening spring, which is interposed between the valve housing and the movable core and urges the movable core toward the valve opening side.

5. The fuel injection valve according to claim 1 , wherein:
the magnetic yoke includes:
a first yoke portion that has a cylindrical peripheral wall part; and
a second yoke portion that radially inwardly projects from the cylindrical peripheral wall part of the first yoke portion;

the entire axial extent of the holding hole is at least partially located within an axial extent of the second yoke portion; and
the predetermined portion includes an opening, which is formed in the second yoke portion and receives a dielectric material.

6. The fuel injection valve according to claim 5 , wherein the entire axial extent of the holding hole is entirely located within the axial extent of the second yoke portion.

7. The fuel injection valve according to claim 5 , wherein:
the solenoid device includes:
a solenoid coil, which is radially placed between the cylindrical peripheral wall part of the first yoke portion and the stationary core; and
a plurality of terminals that are electrically connected to the solenoid coil and extend outward through the opening of the second yoke portion; and

the dielectric material, which is received in the opening of the second yoke portion, holds the plurality of terminals in the opening of the second yoke portion.

8. The fuel injection valve according to claim 7 , wherein:
the valve housing includes a magnetic portion, which is made of a magnetic material;
the stationary core is fixed to an inner peripheral surface of the magnetic portion of the valve housing;
a contact surface of a radially inner end part of the second yoke portion contacts an outer peripheral surface of the magnetic portion of the valve housing;
the entire axial extent of the holding hole is at least partially located within an axial extent of the contact surface of the radially inner end part of the second yoke portion; and
the solenoid coil is radially placed between the cylindrical peripheral wall part of the first yoke portion and the magnetic portion of the valve housing.

Assignees

• Denso Corp

Inventors

• Imai Keita
• Itoh Eiji
• Nagatomo Hiroaki

Classifications

• F02M51/0614 Primary

  characterised by arrangement of electromagnets or fixed armature · CPC title

• F02M2200/08

  Fuel-injection apparatus having special means for influencing magnetic flux, e.g. for shielding or guiding magnetic flux · CPC title

• F02M51/0685

  the armature and the valve being allowed to move relatively to each other or not being attached to each other · CPC title