# US 2014/0196687 A1 · In-Cylinder Dynamic Gas Blending Fuel Injector And Dual Fuel Engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196687 A1 - Document ID: US20140196687A1 - Status: Published application - Kind: A1 - Application number: 13/741,851 - Filed: 2013-01-15 - Published: 2014-07-17 - Earliest claimed: 2013-01-15 - Assignees: Caterpillar Inc. - Applicants: Caterpillar, Inc. - Inventors: Dana R. Coldren; Cory A. Brown - Web page: https://patentgrep.com/patent/US20140196687A1 ## CPC - F02D 19/0642: {at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions} - F02D 19/0694: {operating with a plurality of fuels} - F02D 19/08: simultaneously using pluralities of fuels (F02D19/12 takes precedence) - F02D 19/10: peculiar to compression-ignition engines in which the main fuel is gaseous - F02M 43/04: Injectors peculiar thereto - F02M 45/086: {Having more than one injection-valve controlling discharge orifices} - F02M 47/027: {Electrically actuated valves draining the chamber to release the closing pressure} - Y02T 10/30: Use of alternative fuels, e.g. biofuels - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A dual fuel engine utilizes a compression ignited pilot injection of liquid diesel fuel to ignite a mixture of gaseous fuel and air in each engine cylinder. The gaseous fuel is injected at a relatively low pressure directly into the engine cylinder from a fuel injector. The liquid diesel fuel is injected directly into the engine cylinder from the same fuel injector. In-cylinder dynamic gas blending during the compression stroke can reduce potential hydrocarbon slip that could occur when unburned fuel resides in crevice volumes within the engine cylinder. ## Claims ### Claim 1 A dual fuel engine comprising: an engine housing defining a plurality of cylinders; a plurality of fuel injectors, each having an injector body that defines a liquid nozzle outlet set and a gaseous nozzle outlet set that open into one of the cylinders, and defines a liquid fuel inlet, a gaseous fuel inlet and a drain outlet, and including a liquid needle valve member that opens and closes the liquid nozzle outlet set, and a gaseous needle valve member that opens and closes the gaseous nozzle outlet set, and including a first electrical actuator operably coupled to the liquid needle valve member, and a second electrical actuator operably coupled to the gaseous needle valve member; a high pressure liquid fuel common rail fluidly connected to the liquid fuel inlet of each of the fuel injectors; a low pressure gaseous fuel common rail fluidly connected to the gaseous fuel inlet of each of the fuel injectors; a drain line fluidly connected to the drain outlet; and each of the fuel injectors includes a drain annulus that surrounds the gaseous needle valve member, and is fluidly connected to the drain outlet. ### Claim 2 (depends on 1) The engine of claim 1 including a plurality of pistons that each reciprocate in one of the cylinders between a bottom dead center position and a top dead center position that define a compression ratio greater than 14:1. ### Claim 3 (depends on 2) The engine of claim 2 wherein a ratio of a pressure in the high pressure liquid fuel common rail to a pressure in the low pressure gaseous fuel common rail is at least 4:1. ### Claim 4 (depends on 3) The engine of claim 3 wherein the drain line is fluidly connected to a liquid tank; a pressure regulator positioned in the drain line; wherein a pressure in the drain line is greater than the pressure in the low pressure gaseous fuel common rail; and a ratio of the pressure in the drain line to the pressure in the low pressure gaseous fuel common rail is about one. ### Claim 5 (depends on 4) The engine of claim 4 wherein the liquid needle valve member has an opening hydraulic surface exposed to fluid pressure in the high pressure liquid fuel common rail; and the gaseous needle valve member has an opening hydraulic surface exposed to fluid pressure in the high pressure liquid fuel common rail. ### Claim 6 (depends on 5) The engine of claim 5 including a first needle control chamber and a second needle control chamber disposed in the injector body of each of the fuel injectors and fluidly connected to the liquid fuel inlet; the liquid needle valve member has a closing hydraulic surface exposed to fluid pressure in the first needle control chamber; and the gaseous needle valve member has a closing hydraulic surface exposed to fluid pressure in the second needle control chamber. ### Claim 7 (depends on 6) The engine of claim 6 wherein the liquid nozzle outlet set includes a plurality of nozzle outlets with a first total flow area; the gaseous nozzle outlet set consists of a single nozzle outlet with a second flow area that is greater than the first total flow area. ### Claim 8 (depends on 6) The engine of claim 6 including an O-ring seal in contact with the gaseous needle valve member and the injector body at a location between the gaseous nozzle chamber and the drain annulus. ### Claim 9 A fuel injector comprising: an injector body that defines a liquid fuel inlet, a gaseous fuel inlet, a liquid nozzle outlet set, a gaseous nozzle outlet set and a drain outlet; a first electrical actuator, a second electrical actuator, a liquid nozzle chamber, a gaseous nozzle chamber, a first needle control chamber and a second needle control chamber disposed in the injector body; the liquid nozzle chamber, the first needle control chamber and the second needle control chamber being fluidly connected to the liquid fuel inlet; the gaseous nozzle chamber being fluidly connected to the gaseous fuel inlet a first control valve member operably coupled to the first electrical actuator and being movable between a first position that blocks the first needle control chamber to the drain outlet, and a second position that fluidly connects the first needle control chamber to the drain outlet; a second control valve member operably coupled to the second electrical actuator and being movable between a first position that blocks the second needle control chamber to the drain outlet, and a second position that fluidly connects the second needle control chamber to the drain outlet; a liquid needle valve member with an opening hydraulic surface exposed to fluid pressure in the liquid nozzle chamber, and a closing hydraulic surface exposed to fluid pressure in the first needle control chamber, and being movable between a closed position blocking the liquid nozzle chamber to the liquid nozzle outlet set, and an open position fluidly connecting the liquid nozzle chamber to the liquid nozzle outlet set; a gaseous needle valve member with an opening hydraulic surface exposed to fluid pressure in the liquid nozzle chamber, and a closing hydraulic surface exposed to fluid pressure in the second needle control chamber, and being movable between a closed position blocking the gaseous nozzle chamber to the gaseous nozzle outlet set, and an open position fluidly connecting the gaseous nozzle chamber to the gaseous nozzle outlet set; a drain annulus surrounding the gaseous needle valve member and being fluidly connected to the drain outlet. ### Claim 10 (depends on 9) The fuel injector of claim 9 wherein liquid nozzle outlet set includes a plurality of nozzle outlets; and the gaseous nozzle outlet set consists of a single nozzle outlet. ### Claim 11 (depends on 9) The fuel injector of claim 9 wherein the injector body includes a tip component that defines the liquid nozzle outlet set and the gaseous nozzle outlet set; the liquid needle valve member has a guide interaction with the tip component; the gaseous needle valve member has a guide interaction with the tip component; and the drain annulus separates an upper guide segment from a lower guide segment for the gaseous needle valve member. ### Claim 12 (depends on 9) The fuel injector of claim 9 wherein the liquid needle valve member has a first centerline; the gaseous needle valve member has a second centerline that is parallel to, but spaced apart from, the first centerline. ### Claim 13 (depends on 9) The fuel injector of claim 9 wherein the first needle control chamber is defined by the injector body, a first floating sleeve and the liquid needle valve member; the second needle control chamber is defined by the injector body, a second floating sleeve and the gaseous needle valve member. ### Claim 14 (depends on 9) The fuel injector of claim 9 including an O-ring seal in contact with the gaseous needle valve member and the injector body at a location between the gaseous nozzle chamber and the drain annulus. ### Claim 15 A method of operating an engine, comprising the steps of: supplying high pressure liquid fuel to a liquid fuel inlet of a fuel injector; supplying low pressure gaseous fuel to a gaseous fuel inlet of the fuel injector; injecting gaseous fuel directly into an engine cylinder from a gaseous nozzle outlet set of the fuel injector; injecting liquid fuel directly into the engine cylinder from a liquid nozzle outlet set of the fuel injector; reducing leakage of liquid fuel into a gaseous nozzle chamber of the fuel injector by moving liquid fuel from a drain annulus that surrounds a gaseous needle valve member toward a drain outlet; compression igniting the injected liquid fuel in the engine cylinder; and igniting a mixture of air and the injected gaseous fuel in the engine cylinder with the compression ignited liquid fuel. ### Claim 16 (depends on 15) The method of claim 15 including a step of maintaining pressure in the drain annulus greater than a pressure in the gaseous nozzle chamber. ### Claim 17 (depends on 15) The method of claim 15 including a step of reducing hydrocarbon slip from the engine cylinder by mixing air with the injected gaseous fuel away from a cylinder wall. ### Claim 18 (depends on 15) The method of claim 15 wherein the gaseous fuel injection step is performed during a compression stroke and completed prior to the liquid fuel injecting step. ### Claim 19 (depends on 15) The method of claim 15 wherein the gaseous fuel injecting step includes controlling movement of the gaseous needle member with liquid fuel; and controlling movement of a liquid needle valve member with liquid fuel. ### Claim 20 (depends on 15) The method of claim 15 including a step of maintaining a liquid fuel pressure at the liquid fuel inlet at least four times as high as a gaseous fuel pressure at the gaseous fuel inlet.