US-20260126025-A1 - DUAL FUEL INJECTOR FOR INJECTION CONTROL AND FUEL METERING, AND METHOD FOR OPERATING SAME

US20260126025A1US 20260126025 A1US20260126025 A1US 20260126025A1US-20260126025-A1

Abstract

A fuel injector in a dual fuel system forms a first nozzle supply passage for a first fuel, a multi-channel nozzle supply path for a second fuel, and a combined-fuel outlet passage. The fuel injector further forms a valve seat and a check control chamber, and includes a control valve movable between a first position and an open position, to control a hydraulic pressure of the second fuel in the check control chamber. The fuel injector further includes a nozzle check movable from a closed position blocking the plurality of nozzle outlets from the combined-fuel outlet passage, to an open position to inject a combined fuel charge containing both the first fuel and the second fuel. The multi-channel nozzle supply passage provides flow area especially for operating the dual fuel system in a diesel-only mode. e

Inventors

Bryan Edward Nelson

Assignees

CATERPILLAR INC.

Dates

Publication Date: 20260507
Application Date: 20241104

Claims (20)

1 . A dual fuel system comprising: a first fuel supply for a first fuel; a second fuel supply for a second fuel; a fuel injector forming a first fuel inlet fluidly connecting a first nozzle supply passage to the first fuel supply, a second fuel inlet fluidly connecting a multi-channel nozzle supply path to the second fuel supply, and a combined-fuel outlet passage fluidly connected to both the first nozzle supply passage and to the multi-channel nozzle supply path and extending to a plurality of nozzle outlets; the fuel injector further forming a valve seat, and including a control movable between a first position in contact with the valve seat and blocking the multi-channel nozzle supply path from the second fuel inlet, and an open position; and the fuel injector further including a nozzle check movable from a closed position blocking the plurality of nozzle outlets from the combined-fuel outlet passage, to an open position to inject a combined fuel charge containing both the first fuel and the second fuel.
2 . The dual fuel system of claim 1 wherein the multi-channel nozzle supply path includes a first fuel passage and a second fuel passage extending in parallel to a metering cavity for the second fuel.
3 . The dual fuel system of claim 2 wherein the metering cavity circumferentially extends around the nozzle check.
4 . The dual fuel system of claim 2 further including a first non-return valve in the first fuel passage and a second non-return valve in the second fuel passage.
5 . The dual fuel system of claim 4 wherein the first non-return valve is spring-biased and the second non-return valve includes a passively operated ball check.
6 . The dual fuel system of claim 2 wherein the control valve further includes a pin blocking both of the first fuel passage and the second fuel passage from the second fuel inlet when the control valve is at the first position.
7 . The dual fuel system of claim 6 further including a second valve seat formed in the fuel injector, and wherein the pin contacts the second valve seat to block one of the first fuel passage or the second fuel passage when the control valve is at the first position.
8 . A fuel injector comprising: an injector housing forming a first nozzle supply passage for a first fuel, a multi-channel nozzle supply path for a second fuel, a combined-fuel outlet passage fluidly connected to both the first nozzle supply passage and the multi-channel nozzle supply path and extending to a plurality of nozzle outlets; the injector housing further forming a valve seat, a check control chamber, and a fuel inlet for the second fuel; a control valve movable between a first position and an open position, to vary a hydraulic pressure of the second fuel in the check control chamber, and to selectively fluidly connect the multi-channel nozzle supply passage to the second fuel inlet; and a nozzle check movable from a closed position blocking the plurality of nozzle outlets from the combined-fuel outlet passage, to an open position, to inject a combined fuel charge containing both the first fuel and the second fuel.
9 . The fuel injector of claim 8 wherein the control chamber is fluidly connected to at least one fuel passage of the multi-channel nozzle supply path when the control valve is at the open position.
10 . The fuel injector of claim 9 further wherein the multi-channel fuel supply path includes a first fuel passage and a second fuel passage extending in parallel to a metering cavity for the second fuel formed in the injector housing.
11 . The fuel injector of claim 10 further including a first non-return valve in the first fuel passage, and a second non-return valve in the second fuel passage.
12 . The fuel injector of claim 10 wherein the injector housing further includes a plurality of stack pieces, and a first one of the plurality of stack pieces forms the valve seat contacted by the control valve at the first position, and each of the first fuel passage and the second fuel passage extends through both the first one of the plurality of stack pieces and a second one of the plurality of stack pieces.
13 . The fuel injector of claim 12 wherein the injector housing further includes a second valve seat formed therein, and the control valve contacts both the first valve seat and the second valve seat at the first position.
14 . The fuel injector of claim 13 wherein the second valve seat is formed in the first one of the plurality of stack pieces, and the control valve further includes an attached pin arranged to contact the second valve seat coincidentally with the contact of the first valve seat by the control valve.
15 . The fuel injector of claim 14 wherein the second fuel inlet connects fluidly between the first valve seat and the second valve seat.
16 . The fuel injector of claim 15 wherein each of the first valve seat and the second valve seat includes a flat valve seat.
17 . A method of operating an engine system comprising: feeding a first fuel into a first nozzle supply passage in a fuel injector; feeding a second fuel into a multi-channel nozzle supply path in the fuel injector; opening a control valve at a first timing to admit the second fuel into the multi-channel nozzle supply path; closing the control valve; opening the control valve at a second timing to reduce a closing hydraulic pressure on a nozzle check in the fuel injector; opening the nozzle check based on the reduction to the closing hydraulic pressure to inject a fuel charge into a cylinder in an engine.
18 . The method of claim 17 wherein the opening the nozzle check injects a combined fuel charge containing both the first fuel and the second fuel.
19 . The method of claim 17 wherein the multi-channel nozzle supply path includes a first fuel passage and a second fuel passage extending in parallel to a metering cavity, and further comprising: advancing a plunger in the fuel injector to increase a pressure of the combined fuel charge to an injection pressure; and inhibiting backflow through the first fuel passage and the second fuel passage during the advancing a plunger by way of a first non-return valve and a second non-return valve, respectively.
20 . The method of claim 17 wherein the opening the control valve at the first timing further includes opening a first valve seat by way of a valve body of the control valve and opening a second valve seat by way of a pin attached to the valve body.

Description

TECHNICAL FIELD The present disclosure relates generally to a dual fuel system, and more particularly to metering a fuel in a fuel injector having a multifunctional control valve and a multi-channel nozzle supply path. BACKGROUND Dual fuel engine systems have been known for decades. While traditional engine systems typically utilize a single fuel type such as diesel, gasoline, or natural gas, in a dual fuel engine system two different fuels each having different desirable properties are typically combusted together in an engine cylinder. In one known strategy, a relatively small pilot charge of a compression-ignition fuel such as diesel is used to ignite a relatively larger main charge of a gaseous fuel such as natural gas. The diesel fuel is relatively easily ignited by way of an increased temperature and pressure in a cylinder, with the ignition of the diesel fuel triggering ignition of the gaseous fuel. More recently, engineers have proposed dual liquid fuel strategies employing a leading fuel and a trailing fuel, both in a liquid form and injected as a single fuel charge. U.S. Pat. No. 11,384,721 B1 proposes a strategy that may operate by injecting a leading diesel fuel followed by a trailing alcohol fuel from the same passage into an engine cylinder for combustion. While the '721 patent undoubtedly has practical applications, there is always room for improvement and development of alternative strategies. SUMMARY In one aspect, a dual fuel system includes a first fuel supply for a first fuel, a second fuel supply for a second fuel, and a fuel injector. The fuel injector forms a first fuel inlet fluidly connecting a first nozzle supply passage to the first fuel supply, a second fuel inlet fluidly connecting a multi-channel nozzle supply path to the second fuel supply, and a combined-fuel outlet passage fluidly connected to both the first nozzle supply passage and to the multi-channel nozzle supply path, and extending to a plurality of nozzle outlets. The fuel injector further forms a valve seat, and includes a control valve movable between a first position in contact with the valve seat and blocking the multi-channel nozzle supply path from the second fuel inlet, and an open position. The fuel injector further includes a nozzle check movable from a closed position blocking the plurality of nozzle outlets from the combined-fuel outlet passage, to an open position to inject a combined fuel charge containing both the first fuel and the second fuel. In another aspect, a fuel injector includes an injector housing forming a first nozzle supply passage for a first fuel, a multi-channel nozzle supply path for a second fuel, a combined-fuel outlet passage fluidly connected to both the first nozzle supply passage and the multi-channel nozzle supply path and extending to a plurality of nozzle outlets. The injector housing further forms a valve seat, a check control chamber, and a fuel inlet for the second fuel. The fuel injector also includes a control valve movable between a first position and an open position, to control a hydraulic pressure of the second fuel in the check control chamber, and to selectively fluidly connect the multi-channel nozzle supply passage to the second fuel inlet. The injector further includes a nozzle check movable from a closed position blocking the plurality of nozzle outlets from the combined-fuel outlet passage, to an open position, to inject a combined fuel charge containing both the first fuel and the second fuel. In yet another aspect, a method of operating an engine system includes feeding a first fuel into a first nozzle supply passage in a fuel injector and feeding a second fuel into a multi-channel nozzle supply path in the fuel injector. The method also includes opening a control valve at a first timing to admit the second fuel into the multi-channel nozzle supply path, closing the control valve, and opening the control valve at a second timing to reduce a closing hydraulic pressure on a nozzle check in the fuel injector. The method further includes opening the nozzle check based on the reduction to the closing hydraulic pressure to inject a fuel charge into a cylinder in an engine. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagrammatic view of a dual fuel engine system, according to one embodiment; FIG. 2 is a sectioned side diagrammatic view of a fuel injector suitable for use in the engine system of FIG. 1; and FIG. 3 is a sectioned side diagrammatic view through a portion of the fuel injector as in FIG. 2. DETAILED DESCRIPTION Referring to FIG. 1, there is shown a dual fuel internal combustion engine system 10 (hereafter “engine system 10”), according to one embodiment. Engine system 10 includes a dual fuel engine 12 (hereafter “engine 12”) having an engine housing 14 with a plurality of combustion cylinders 16 formed therein. Engine housing 14 will typically include a cylinder block forming cylinders 16, and an engine head arranged in one or more engine head sections. It