FUEL SYSTEM FOR A MULTI-FUEL ENGINE
First Claim
1. A method of operating a fuel system including a first fuel pump coupled upstream of a second, positive-displacement fuel pump, comprising,when second fuel pump operation is not requested,operating the first fuel pump to maintain a fuel rail pressure at a fuel rail while supplying fuel to an engine cylinder through an injector;
- andadjusting a degree of operation of the second fuel pump to maintain an elevated pressure in a pump chamber of the second fuel pump below the fuel rail pressure.
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Accused Products
Abstract
Methods and systems are provided for operating an engine fuel system including a low pressure pump and a high pressure pump. During conditions when direct injection is not requested, a fuel rail pressure is maintained by the low pressure pump and fuel is port injected. Further, a stroke amount of the high pressure pump is adjusted to maintain an outlet pressure of the high pressure pump just below the fuel rail pressure. By maintaining fuel flow within the high pressure pump when high pressure pump operation is not required, and without flowing fuel from the high pressure pump outlet into the fuel rail, the high pressure pump may be cooled and lubricated without affecting the fuel rail pressure.
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Citations
21 Claims
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1. A method of operating a fuel system including a first fuel pump coupled upstream of a second, positive-displacement fuel pump, comprising,
when second fuel pump operation is not requested, operating the first fuel pump to maintain a fuel rail pressure at a fuel rail while supplying fuel to an engine cylinder through an injector; - and
adjusting a degree of operation of the second fuel pump to maintain an elevated pressure in a pump chamber of the second fuel pump below the fuel rail pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of operating a fuel system including a low pressure fuel pump (LPP) coupled upstream of a high pressure fuel pump (HPP), comprising,
when HPP operation is not requested, operating the LPP to maintain a fuel rail pressure in a fuel rail while injecting fuel into an engine cylinder; -
adjusting a stroke amount of the HPP responsive to fuel rail pressure to maintain a pump chamber outlet pressure of the HPP within a threshold pressure, but below the fuel rail pressure; and intermittently pulsing the HPP stroke amount to intermittently flow fuel from an outlet of the HPP into the fuel rail. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A fuel system for an internal combustion engine, comprising:
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a first fuel tank storing a first fuel type; a group of port fuel injectors in communication with a group cylinders; a group of direct injectors in communication with the group of cylinders; a first low pressure fuel pump coupled to the first fuel tank and positioned upstream of a second high pressure fuel pump, the first fuel pump in communication with the group of port fuel injectors via a first fuel rail, the second fuel pump in communication the group of port fuel injectors via a solenoid valve, the second fuel pump further communicating with the group of direct injectors via a second fuel rail; and a control system configured with instructions for; when second fuel pump operation is not requested, operating the first fuel pump to maintain a first fuel rail pressure in the first fuel rail while supplying the first fuel type to the group of cylinders through the group of port injectors; and adjusting operation of the second fuel pump to maintain an elevated pressure in a pump chamber of the second fuel pump below the first fuel rail pressure. - View Dependent Claims (19, 20, 21)
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Specification