Fuel injector and fuel injection device using the same

Patent metadata

Field	Value
Publication number	US-9249766-B2
Application number	US-201414152541-A
Country	US
Kind code	B2
Filing date	Jan 10, 2014
Priority date	Jan 14, 2013
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

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−Ffo≦L×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.

First claim

What is claimed is:

1. A fuel injector comprising:
a coil generating a magnetic flux when being energized;
a stator core generating a part of a magnetic circuit as a passage of the magnetic flux, the stator core generating an electromagnetic force;
a movable core moved by the electromagnetic force;
a valve body moved together with the movable core, the valve body 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, wherein
an elastic coefficient of the elastic-force applying portion is set to meet a condition that Ffc−Ffo≦L×K, wherein among fuel-pressure valve-closing forces applied to the valve body in the valve-closing direction by a fuel pressure, the fuel-pressure valve-closing force of when the valve body is closed is referred to as Ffc, the fuel-pressure valve-closing force of when the valve body is moved to a position where 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, and the elastic coefficient is referred to as K.

2. The fuel injector according to claim 1 , wherein
the elastic coefficient K is set to meet a condition that a value of (Ffx+Lx×K) is continuously increased during a time period from a time point that the movement distance becomes Lx to a time point that the movement distance becomes L, wherein the fuel-pressure valve-closing force of when the valve body is moved to a predetermined position is referred to as Ffx, and the movement distance of the valve body from the time point that the valve body is closed to a time point that the valve body is moved to the predetermined position is referred to as Lx.

3. The fuel injector for a combustion system that has an internal combustion engine operating according to a combustion of fuel injected from the injection port, and a fuel pump driven by the internal combustion engine and generating the fuel pressure, according to claim 1 , wherein
the elastic coefficient K is set to meet the condition, when the internal combustion engine is running at an idle operation.

4. The fuel injector according to claim 3 , wherein
the elastic coefficient K is set not to meet the condition, when the internal combustion engine is running at a high-speed operation that a rotational speed of the internal combustion engine is greater than or equal to a predetermined speed.

5. The fuel injector according to claim 1 , wherein
when the valve body is closed, the elastic force of the elastic-force applying portion is referred to as Fsc, the elastic force of the elastic-force applying portion is referred to as Ffc, and the elastic coefficient K is set to meet a condition that Fsc≧Ffc.

6. The fuel injector according to claim 1 , wherein
the valve body is slidable with respect to the movable core,
the elastic-force applying portion has
a main spring which is a spring applying the elastic force to the valve body in the valve-closing direction, and is provided to increase the elastic force in the valve-closing direction in accordance with an increase in stroke of the valve body, and
a sub spring which is a spring applying the elastic force to the valve body via the movable core in the valve-opening direction, and is provided to decrease the elastic force in a valve-opening direction in accordance with the increase in stroke of the valve body, and

the elastic coefficient K is a value combined an elastic coefficient K 1 of the main spring with an elastic coefficient K 2 of the sub spring.

7. The fuel injector according to claim 6 , wherein
the elastic coefficient K 1 is greater than the elastic coefficient K 2 .

8. The fuel injector according to claim 1 , further comprising:
a seating surface ring-shaped and provided at an outer peripheral surface of the valve body, and
a body defining the injection port, the body having a seated surface, wherein
the seating surface abuts on the seated surface to close the injection port.

9. The fuel injector according to claim 8 , wherein
the seating surface has a curved portion.

10. A fuel injector comprising:
a coil generating a magnetic flux when being energized;
a stator core generating a part of a magnetic circuit as a passage of the magnetic flux, the stator core generating an electromagnetic force;
a movable core moved by the electromagnetic force;
a valve body moved together with the movable core, the valve body 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, wherein
an elastic coefficient of the elastic-force applying portion is set to meet a condition that a value of (Ffx+Lx×K) is continuously increased during a time period from a time point that the movement distance becomes Lx to a time point that the movement distance becomes L, wherein among fuel-pressure valve-closing forces applied to the valve body in the valve-closing direction by a fuel pressure, the fuel-pressure valve-closing force of when the valve body is moved to a predetermined position is referred to as Ffx, the 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 moved to the predetermined position is referred to as Lx, a movement distance of the valve body from the time point that the valve body is closed to a time point that the valve body is completely opened is referred to as L, and the elastic coefficient is referred to as K.

11. The fuel injector for a combustion system that has an internal combustion engine operating according to a combustion of fuel injected from the injection port, and a fuel pump driven by the internal combustion engine and generating the fuel pressure, according to claim 10 , wherein
the elastic coefficient K is set to meet the condition, when the internal combustion engine is running at an idle operation.

12. The fuel injector according to claim 11 , wherein
the elastic coefficient K is set not to meet the condition, when the internal combustion engine is running at a high-speed operation that a rotational speed of the internal combustion engine is greater than or equal to a predetermined speed.

13. The fuel injector according to claim 10 , wherein
when the valve body is closed, the elastic force of the elastic-force applying portion is referred to as Fsc, the elastic force of the elastic-force applying portion is referred to as Ffc, and the elastic coefficient K is set to meet a condition that Fsc≧Ffc.

14. The fuel injector according to claim 10 , wherein
the valve body is slidable with respect to the movable core,
the elastic-force applying portion has
a main spring which is a spring applying the elastic force to the valve body in the valve-closing direction, and is provided to increase the elastic force in the valve-closing direction in accordance with an increase in stroke of the valve body, and
a sub spring which is a spring applying the elastic force to the valve body via the movable core in the valve-opening direction, and is provided to decrease the elastic force in a valve-opening direction in accordance with the increase in stroke of the valve body, and

the elastic coefficient K is a value combined an elastic coefficient K 1 of the main spring with an elastic coefficient K 2 of the sub spring.

15. The fuel injector according to cl

Assignees

• Denso Corp

Inventors

• Imai Keita
• Itoh Eiji

Classifications

• F02M51/0664 Primary

  having a cylindrically or partly cylindrically shaped armature, e.g. entering the winding; having a plate-shaped or undulated armature entering the winding · CPC title

• F02M51/0675

  the valve body having cylindrical guiding or metering portions, e.g. with fuel passages · CPC title

• F02M61/205

  Means specially adapted for varying the spring tension or assisting the spring force to close the injection-valve, e.g. with damping of valve lift · CPC title