Fuel injector, a fuel injector assembly and an associated method

Patent metadata

Field	Value
Publication number	US-10851753-B2
Application number	US-201615335066-A
Country	US
Kind code	B2
Filing date	Oct 26, 2016
Priority date	Oct 30, 2015
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

A fuel injector is provided which has a valve member, a valve member guide and a spring chamber. Discharge of fuel out of a fuel injector outlet is controlled by movement of the valve member within a bore of the valve member guide. The spring chamber contains a biasing member, which is a compression spring, and which biases the valve member into contact with a valve seat when in a closed configuration. The fuel supply passage is provided, which by-passes the spring chamber, to direct a flow of the fuel to an outlet chamber of the fuel injector, and the cleaning fluid supply passage is provided to supply a pressurized cleaning fluid to a second end of the bore to restrict leakage of the fuel from the outlet chamber towards the second end of the bore along a clearance extending between the valve member and the valve member guide.

First claim

The invention claimed is:

1. A fuel injector comprising a valve member, a valve member guide, a spring chamber, a fuel supply passage and a cleaning fluid supply passage;
the valve member being movable with respect to the valve member guide into and out of contact with a valve seat of the fuel injector to thereby control discharge of a fuel out of a fuel injector outlet;
the valve member guide defining a bore which receives the valve member, the bore being configured to guide the valve member during sliding movement of the valve member into and out of contact with the valve seat, the bore comprising a first end proximate the fuel injector outlet and a second end distal the fuel injector outlet with the bore and a portion of an outer surface of the valve member disposed between the first end and the second end of the bore defining a clearance distance between the valve member and the valve member guide, and the valve member guide defining a drainage passage extending from the bore to an outer surface of the valve member guide and intersecting the bore at a drainage port located between the first end and the second end of the bore, wherein the valve member guide comprises an annular drainage gallery defined in the bore and intersected by the drainage passage at the drainage port;
the spring chamber containing a biasing member which biases the valve member into contact with the valve seat, the spring member being in fluid communication with the second end of the bore;
the fuel supply passage being configured to direct a flow of the fuel at a first pressure to an outlet chamber of the fuel injector, the outlet chamber being in fluid communication with the first end of the bore and the valve member; wherein the fuel supply passage by-passes the spring chamber; and
the cleaning fluid supply passage being in fluid communication with the spring chamber and configured to supply a pressurised cleaning fluid at a second pressure greater than the first pressure to the second end of the bore to restrict leakage of the fuel from the outlet chamber towards the second end of the bore along the clearance, and configured to simultaneously supply the pressurised cleaning fluid when the fuel supply passage is directing the flow of fuel to the outlet chamber.

2. The fuel injector as claimed in claim 1 , wherein pressurization of the fuel within the outlet chamber enables sliding movement of the valve member away from the fuel injector outlet to thereby lift off the valve member from the valve seat to allow discharge of fuel from the outlet chamber out of the fuel injector outlet.

3. The fuel injector as claimed in claim 1 , wherein the biasing member is a spring, or a magnetically-driven actuator.

4. The fuel injector as claimed in claim 1 , wherein the spring chamber forms a part of the cleaning fluid supply passage.

5. The fuel injector as claimed in claim 4 , wherein the spring chamber comprises an entry port to receive pressurised cleaning fluid and an exit port in fluid communication with the second end of the bore, wherein the exit port is located at a first end of the spring chamber proximate the fuel injector outlet and the entry port is located at a second end of the spring chamber distal the fuel injector outlet.

6. The fuel injector as claimed in claim 1 , wherein the drainage passage by-passes the spring chamber.

7. The fuel injector as claimed in claim 1 , further comprising a fuel injector body which retains the valve member guide, wherein at least a portion of a drainage path extends along an interface of the fuel injector body and the valve member guide.

8. The fuel injector as claimed in claim 7 , wherein at least a portion of the drainage path extends along an interface of the fuel injector body and a housing of the spring chamber.

9. A fuel injection assembly comprising a fuel injection pump, a cleaning fluid pump and a fuel injector as claimed in claim 1 ;
the fuel injection pump comprising a fuel supply conduit in fluid communication with the fuel supply passage of the fuel injector; and
the cleaning fluid pump comprising a cleaning fluid supply conduit in fluid communication with the cleaning fluid supply passage of the fuel injector.

10. The fuel injection assembly of claim 9 , further comprising a cleaning fluid sensor configured to sense a volumetric flow rate or volume of a cleaning fluid conveyed, in use, through the cleaning fluid supply conduit.

11. The fuel injection assembly of claim 9 , wherein the fuel injection pump supplies a pressurised flow of fuel to the outlet chamber of the fuel injector via the fuel supply passage and the cleaning fluid pump supplies a pressurised flow of cleaning fluid to the second end of the bore of the fuel injector via the cleaning fluid supply passage.

12. The fuel injection assembly of claim 11 wherein the cleaning fluid at the second end of the bore of the fuel injector creates a flow of the cleaning fluid between the valve member and the valve member guide towards the fuel injector outlet.

13. The fuel injection assembly of claim 11 , wherein the biasing force supplied by the biasing member of the fuel injector and the pressurised flow of cleaning fluid set a lift-off pressure for the outlet chamber of the fuel injector at which the valve member is moved out of contact with the valve seat.

14. The fuel injection assembly of claim 11 , wherein a spring seat plug is located within a spring chamber and is received on a second end of the valve member.

Assignees

• Caterpillar Inc

Inventors

• Mawhinney Graeme
• Stockner Alan R
• Stark Paul
• Mack David

Classifications

• F02M61/02 Primary

  of valveless type · CPC title

• F02M65/008 Primary

  of injectors only · CPC title

• F02M61/16 Primary

  Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14 · CPC title

• F02M65/007

  Cleaning · CPC title

• F02M43/04 Primary

  Injectors peculiar thereto · CPC title