Injection control valve in fuel injector configured for pressure relief

Patent metadata

Field	Value
Publication number	US-12331708-B2
Application number	US-202318489037-A
Country	US
Kind code	B2
Filing date	Oct 18, 2023
Priority date	Oct 18, 2023
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

A fuel injector includes a nozzle, and a nozzle check including a closing hydraulic surface. The fuel injector also includes a high pressure passage, a low pressure drain, a control passage, a check control chamber, and a valve seat. A relief passage is formed by at least one of an injector housing or a control valve in a control valve assembly. The control valve is movable among a rest position, a lifted injection position, and a lifted relief position where the high pressure passage connects to the relief passage. The control valve can be operated to selectively connect the high pressure passage to the relief passage to bleed fuel pressure to prevent over-pressurization. Related apparatus and methodology is also disclosed.

First claim

What is claimed is:

1. A fuel injector comprising:
an injector housing including a nozzle;
a nozzle check movable to open and close the nozzle and including a closing hydraulic surface;
an electrically actuated control valve assembly including a control valve, and an armature;
a high pressure passage, a low pressure drain, a control passage, a check control chamber fluidly connected to the control passage, and a valve seat are each formed in the injector housing, and a relief passage is formed by at least one of the injector housing or the control valve; and
the control valve is movable among a rest position in contact with the control valve seat and blocking the control passage from the low pressure drain to maintain a high pressure in the control chamber, a lifted injection position where the control passage is fluidly connected to the low pressure drain and the control valve blocks the high pressure passage, and a lifted relief position where the control valve does not block the high pressure passage, the high pressure passage is fluidly connected to the relief passage, and the control passage is blocked from the low pressure drain.

2. The fuel injector of claim 1 wherein at the lifted relief position the control valve blocks the control passage from both the low pressure drain and the relief passage.

3. The fuel injector of claim 1 wherein the control valve is movable a travel distance linearly among the rest, lifted injection, and lifted relief positions, and at the lifted relief position the control valve is between the rest position and the lifted injection position.

4. The fuel injector of claim 3 wherein the rest position includes a first stop position and the lifted injection position includes a second stop position, and further comprising a first biasing spring biasing the control valve in at least a portion of the travel distance, and a second biasing spring biasing the control valve in only a portion of the travel distance.

5. The fuel injector of claim 4 wherein the first biasing spring includes a closing biasing spring biasing the control valve toward the rest position, and the second biasing spring includes a lifting biasing spring biasing the control valve away from the rest position.

6. The fuel injector of claim 4 wherein each of the first biasing spring and the second biasing spring includes a closing biasing spring biasing the control valve toward the rest position.

7. The fuel injector of claim 1 wherein a plunger cavity is formed in the injector housing and fluidly connected to the high pressure passage.

8. The fuel injector of claim 7 further comprising a plunger movable in the plunger cavity, and a tappet coupled to the plunger.

9. The fuel injector of claim 7 wherein the injector housing defines a low pressure space, and further comprising an electrically actuated spill valve movable in the injector housing between an open position fluidly connecting the plunger cavity to the low pressure space, and a closed position.

10. A fuel system comprising:
a fuel supply;
a fuel injector including therein a fuel inlet fluidly connected to the fuel supply, a high pressure passage extending from a plunger cavity, a control passage, and a low pressure drain;
the fuel injector further including an electrically actuated spill valve fluidly between the fuel inlet and the plunger cavity, a nozzle check having a closing hydraulic surface exposed to a fluid pressure of the control passage, and an electrically actuated control valve;
the control valve including a 3-position valve fluidly blocking the control passage from the low pressure drain at a rest position, and fluidly connecting the control passage to the low pressure drain at a lifted injection position; and
the fuel injector further including therein a relief passage, and the control valve fluidly connects the high pressure passage to the relief passage and blocks the control passage from the low pressure drain at a lifted relief position that is between the rest position and the lifted injection position.

11. The fuel system of claim 10 wherein the rest position includes a first stop position and the lifted injection position includes a second stop position.

12. The fuel system of claim 10 further comprising a biasing spring biasing the control valve in only a portion of a travel distance between the rest position and the lifted injection position.

13. The fuel system of claim 12 wherein the biasing spring includes a closing biasing spring biasing the control valve toward the rest position.

14. The fuel system of claim 12 wherein the biasing spring includes a lifting biasing spring biasing the control valve away from the rest position.

15. The fuel system of claim 12 further comprising a second biasing spring biasing the control valve in the full travel distance between the rest position and the lifted injection position.

16. A method of operating a fuel system comprising:
advancing a plunger in the fuel system to increase a pressure of fuel in a plunger cavity;
energizing or deenergizing a solenoid in a fuel injector, during the advancing the plunger, to move a control valve to a lifted relief position from one of a rest position blocking a control passage from a low pressure drain or a lifted injection position where the control passage is fluidly connected to the low pressure drain;
fluidly connecting a high pressure passage extending from the plunger cavity to a relief passage, based on the moving the control valve to the lifted relief position, to relieve a pressure of fuel in the plunger cavity;
blocking the control passage from the relief passage at the lifted relief position; and
holding a nozzle check in the fuel injector closed via a pressure of fuel on a closing hydraulic surface of the nozzle check exposed to a fluid pressure of the control passage, during the relieving the pressure of fuel in the plunger cavity.

17. The method of claim 16 further comprising:
energizing the solenoid a first time in an engine cycle to move the control valve to the lifted injection position during the advancing the plunger; and
energizing the solenoid a second time in the engine cycle to move the control valve to the lifted injection position during the advancing the plunger.

18. The method of claim 17 wherein the energizing or deenergizing the solenoid includes energizing the solenoid to a first energy state, and each of the energizing the solenoid a first time and the energizing the solenoid a second time includes energizing the solenoid to a second, higher energy state.

19. The method of claim 18 further comprising applying a lesser spring bias to the control valve in a portion of a travel path between the rest position and the lifted injection position, and applying a greater spring bias to the control valve in a portion of the travel path from the lifted relief position to the lifted injection position.

20. The method of claim 19 further comprising disengaging a biasing spring from the control valve in a portion of the travel path.

Assignees

• Caterpillar Inc

Inventors

• Ledford Jeffrey E
• Juchems Mitchell
• Marrack Andrew O

Classifications

• F02D41/3005

  Details not otherwise provided for · CPC title

• F02M63/007

  Details not provided for in, or of interest apart from, the apparatus of the groups F02M63/0014 - F02M63/0059 · CPC title

• F02M63/0033

  Lift valves, i.e. having a valve member that moves perpendicularly to the plane of the valve seat · CPC title

• F02M63/0017

  using electromagnetic operating means · CPC title

• F02M47/027 Primary

  Electrically actuated valves draining the chamber to release the closing pressure · CPC title