Systems for fuel delivery

Abstract

Various systems are provided for delivering fuel to an engine. In one example, a system includes a controller and a fluid system configured to maintain a fluid at a pressure downstream of a check valve. The controller may be configured to determine if a leak is present in the fluid system based on a first pressure decay rate of the fluid system, and responsive to identifying that a leak is present in the fluid system, differentiate between an internal leak and an external leak based on a leak flow rate as fluid system pressure decreases.

1 . A system, comprising:
 a gaseous fuel supply system to supply gaseous fuel from a gaseous fuel storage source to an engine having a plurality of cylinders; and   a controller configured to:
 detect a request to shut down the engine; and 
 in response to detecting the request, remove gaseous fuel trapped within the gaseous fuel supply system by closing a gaseous fuel supply valve and selectively fueling gaseous fuel to the engine. 
   
     
     
         2 . The system of  claim 1 , wherein the gaseous fuel supply system comprises a gaseous fuel rail including a plurality of gas admission valves, each gas admission valve to supply gaseous fuel to a respective cylinder of the plurality of cylinders, wherein the gaseous fuel supply valve is located upstream of the gaseous fuel rail, and wherein the gaseous fuel trapped within the gaseous fuel supply system is trapped between the gaseous fuel supply valve and plurality of gas admission valves. 
     
     
         3 . The system of  claim 1 , wherein the engine is configured to combust liquid fuel and gaseous fuel, wherein to selectively fuel gaseous fuel to the engine, the controller is configured to supply both gaseous fuel and liquid fuel to each cylinder of a subset of cylinders of the plurality of cylinders, thereby to combust the gaseous fuel trapped within the gaseous fuel supply system, the subset including at least one cylinder but less than all cylinders of the plurality of cylinders. 
     
     
         4 . The system of  claim 3 , wherein a number of cylinders in the subset of cylinders is selected based on one or more of an initial gaseous fuel supply system pressure, an upper limit gaseous fuel substitution ratio, a lower limit gaseous fuel substitution ratio, or a threshold time limit. 
     
     
         5 . The system of  claim 3 , wherein in response to detecting that the gaseous fuel trapped within the gaseous fuel supply system has been removed, the controller is further configured to shut down the engine. 
     
     
         6 . The system of  claim 1 , wherein the engine is configured to combust liquid fuel and gaseous fuel, wherein to selectively fuel gaseous fuel to the engine, the controller is configured to supply only gaseous fuel to a subset of cylinders of the plurality of cylinders and to combust only liquid fuel in remaining cylinders of the plurality of cylinders. 
     
     
         7 . The system of  claim 1 , wherein to selectively fuel gaseous fuel to the engine, the controller is configured to supply only gaseous fuel to the engine while the engine is turning but combustion is not occurring prior to an engine restart following the request to shut down the engine. 
     
     
         8 . The system of  claim 1 , further comprising a gaseous fuel canister fluidically coupled to the gaseous fuel supply system, where the controller is configured to open a vent valve in a vent line coupled between the gaseous fuel canister and the gaseous fuel rail in response to receiving the request to shut down the engine. 
     
     
         9 . The system of  claim 1 , further comprising an ignition source fluidically coupled to the gaseous fuel supply system via a vent line and a vent valve positioned in the vent line between the gaseous fuel supply system and the ignition source, and wherein the controller is configured to further remove gaseous fuel trapped within the gaseous fuel supply system by opening the vent valve and activating the ignition source in response to the request to shut down the engine. 
     
     
         10 . A system, comprising:
 an engine having a plurality of cylinders configured to combust liquid fuel and gaseous fuel;   a gaseous fuel supply system including a gaseous fuel rail having a plurality of gas admission valves, each gas admission valve to supply gaseous fuel to a respective cylinder of the plurality of cylinders, and a gaseous fuel supply valve located upstream of the gaseous fuel rail;   an expansion chamber fluidically coupled to the gaseous fuel supply system; and   a controller configured to:
 detect a request to shut down the engine; and 
   in response to detecting the request, remove gaseous fuel trapped within the gaseous fuel supply system by closing the gaseous fuel supply valve and expanding the gaseous fuel in the expansion chamber.   
     
     
         11 . The system of  claim 10 , wherein the controller is further configured to, in response to a subsequent request to restart the engine following the shutdown of the engine, direct the gaseous fuel in the expansion chamber back to the gaseous fuel supply system. 
     
     
         12 . The system of  claim 10 , further comprising an ignition source fluidically coupled to the gaseous fuel supply system via a vent line and a vent valve positioned in the vent line between the gaseous fuel supply system and the ignition source, and wherein the controller is configured to further remove gaseous fuel trapped within the gaseous fuel supply system by opening the vent valve and activating the ignition source in response to the request to shut down the engine. 
     
     
         13 . The system of  claim 10 , wherein the controller is configured to further remove gaseous fuel trapped within the gaseous fuel supply system by selectively fueling gaseous fuel to the engine after closing the gaseous fuel supply valve. 
     
     
         14 . A system, comprising:
 a fluid system in an engine configured to maintain a fluid at a pressure downstream of a check valve; and   a controller configured to:
 determine if a leak is present in the fluid system based on a first pressure decay rate of the fluid system; 
 responsive to identifying that a leak is present in the fluid system, differentiate between an internal leak and an external leak based on a leak flow rate as fluid system pressure decreases; and 
 maintain engine operation in response to determining that the leak is an internal leak and shut down the engine in response to determining that the leak is an external leak. 
   
     
     
         15 . The system of  claim 14 , wherein the fluid system comprises a fuel system of an engine including a high-pressure pump to deliver fuel to a fuel rail, and wherein the check valve is positioned in the high-pressure fuel pump. 
     
     
         16 . The system of  claim 15 , wherein the controller is configured to determine the leak is an internal leak if the leak flow rate increases as pressure in the fuel system decreases. 
     
     
         17 . The system of  claim 15 , wherein the controller is configured to determine the leak is an external leak if the leak flow rate decreases as pressure in the fuel system decreases. 
     
     
         18 . The system of  claim 14 , wherein the leak flow rate is estimated based on a second pressure decay rate. 
     
     
         19 . The system of  claim 14 , further comprising an indicator light configured to be illuminated based on the determination of an external leak or an internal leak.