Fuel injection device

Patent metadata

Field	Value
Publication number	US-10309356-B2
Application number	US-201615749909-A
Country	US
Kind code	B2
Filing date	Jun 21, 2016
Priority date	Aug 6, 2015
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

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.

First claim

The invention claimed is:

1. A fuel injection device comprising:
a nozzle that includes an injection hole, through which fuel is injected, and a valve seat, which is formed around the injection hole and is shaped into a ring form;
a housing that is shaped into a tubular form and has one end connected to the nozzle, wherein the housing has a fuel passage, which is formed in an inside of the housing and is communicated with the injection hole;
a needle that has:
a needle main body, which is shaped into a rod form;
a seal portion, which is formed at one end of the needle main body such that the seal portion is contactable with the valve seat; and
a flange, which is formed on a radially outer side of the needle main body at another end of the needle main body or around the another end of the needle main body, wherein the needle is installed such that the needle is reciprocatable in the fuel passage, and when the seal portion is lifted away from or is seated against the valve seat, the needle opens or closes the injection hole;

a movable core that is installed such that the movable core is movable relative to the needle main body and has a surface, which is opposite from the valve seat and is contactable with a surface of the flange located on the valve seat side of the flange;
a stationary core that is installed on an opposite side of the movable core, which is opposite from the valve seat, in the inside of the housing;
a gap forming member that has:
a plate portion that is placed on the opposite side of the needle, which is opposite from the valve seat, such that one end surface of the plate portion is contactable with the needle; 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 the surface of the movable core located on the stationary core side, wherein the gap forming member is configured to form an axial gap, which is a gap defined in an axial direction between the flange and the movable core, when the plate portion and the extending portion are in contact with the needle and the movable core, respectively; and

a valve seat side spring that is placed on the opposite side of the gap forming member, which is opposite from the valve seat, wherein the valve seat side spring is operable to urge the needle and the movable core toward the valve seat through the gap forming member;
a coil that is operable to attract the movable core toward the stationary core such that the movable core contacts the flange and drives the needle toward the opposite side, which is opposite from the valve seat, when the coil is energized; and
a guide that is placed on the valve seat side of the movable core in the inside of the housing, and wherein an outer wall of the needle main body is slidable relative to the guide to guide reciprocation of the needle, wherein:
the gap forming member is formed such that 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 the stationary core, forms a radial gap, which is a gap defined in a radial direction, between the second wall surface and the inner wall of the stationary core, and the radial gap continuously extends in a circumferential direction along the second wall surface all around the gap forming member to limit contact between the second wall surface and the inner wall of the stationary core.

2. The fuel injection device according to claim 1 , wherein the guide is formed separately from the housing.

3. The fuel injection device according to claim 1 , further comprising:
a spring seat that is shaped into a ring form and is placed at a location, which is on a radially outer side of the needle main body and is between the movable core and the guide; and
a stationary core side spring that is placed between the movable core and the spring seat and has an urging force, which is smaller than an urging force of the valve seat side spring, wherein the stationary core side spring is operable to urge the movable core toward the stationary core.

4. The fuel injection device according to claim 1 , further comprising a limiting portion that is placed at a location, which is on a radially outer side of the needle main body and is between the movable core and the guide, wherein the limiting portion is configured to limit movement of the movable core toward the valve seat through contacting of the limiting portion against a surface of the movable core located on the valve seat side.

5. The fuel injection device according to claim 1 , wherein the gap forming member is made of a non-magnetic material.

6. The fuel injection device according to claim 1 , wherein the stationary core includes a bush, which is shaped into a tubular form and has an inner wall that is opposed to the second wall surface.

7. The fuel injection device according to claim 6 , wherein the bush is configured to limit movement of the movable core in a valve opening direction, which is a direction away from the valve seat, when the bush contacts the movable core.

8. The fuel injection device according to claim 1 , wherein the movable core includes:
a movable core main body; and
a contact portion that is placed on the opposite side of the movable core main body, which is opposite from the valve seat, wherein a hardness of the contact portion is higher than a hardness of the movable core main body, and the contact portion is contactable with at least one of the flange or the extending portion.

9. The fuel injection device according to claim 1 , wherein:
the needle main body has an axial hole that extends in the axial direction from an end surface of the needle main body, which is opposite from the valve seat, while the axial hole is communicated with a space located at an outside of the needle main body; and
the gap forming member has a hole that connects between one end surface and another end surface of the plate portion and is communicatable with the axial hole.

10. The fuel injection device according to claim 1 , wherein the extending portion is shaped into a tubular form.

11. A fuel injection device comprising:
a nozzle that includes an injection hole, through which fuel is injected, and a valve seat, which is formed around the injection hole and is shaped into a ring form;
a housing that is shaped into a tubular form and has one end connected to the nozzle, wherein the housing has a fuel passage, which is formed in an inside of the housing and is communicated with the injection hole;
a needle that has:
a needle main body, which is shaped into a rod form;
a seal portion, which is formed at one end of the needle main body such that the seal portion is contactable with the valve seat; and
a flange, which is formed on a radially outer side of the needle main body at another end of the needle main body or around the another end of the needle main body, wherein the needle is installed such that the needle is reciprocatable in the fuel passage, and when the seal portion is lifted away from or is seated against the valve seat, the needle opens or closes the injection hole;

a movable core that is installed such that the movable core is movable relative to the needle main body and has a surface, which is opposite from the valve seat and is contactable with a surface of the flange located on the valve seat side;
a stationary core that is installed on an opposite side of the movable core, which is opposite from the valve seat, in the

Assignees

• Denso Corp

Inventors

• Oikawa Shinobu
• Matsukawa Tomoji
• Yamamoto Shinsuke
• Gotoh Moriyasu
• Itoh Eiji

Classifications

• F02M51/0671 Primary

  the armature having an elongated valve body attached thereto · CPC title

• F02M51/0653

  the valve being an elongated body, e.g. a needle valve · CPC title

• F02M51/061

  using electromagnetic operating means · CPC title

• F02M51/06

  Injectors peculiar thereto {with means directly operating the valve needle} · CPC title

• F02M61/18

  Injection nozzles, e.g. having valve seats; {Details of valve member seated ends, not otherwise provided for} · CPC title