초록 ▼

A direct injection fuel supply system, in one exemplary implementation, includes a lift fuel pump, a positive displacement pump, at least one fuel injector and an accumulator assembly. The lift pump is adapted to be in fluid communication with a supply of fuel and the positive displacement pump is i

A direct injection fuel supply system, in one exemplary implementation, includes a lift fuel pump, a positive displacement pump, at least one fuel injector and an accumulator assembly. The lift pump is adapted to be in fluid communication with a supply of fuel and the positive displacement pump is in fluid communication with and downstream of the lift pump. The at least one injector is in fluid communication with an outlet of the positive displacement pump via a high pressure fuel line. The accumulator assembly includes an accumulator and a valve, where the valve is in direct fluid communication with the high pressure fuel line and the injector. The valve is selectively controlled to at least one of an open state providing fluid communication between the accumulator and the high pressure fuel line and a closed state blocking fluid communication between the accumulator and the high pressure fuel line.

대표청구항 ▼

1. A direct injection fuel supply system for a vehicle, comprising: a lift fuel pump adapted to be in fluid communication with a supply of fuel;a positive displacement pump in fluid communication with and downstream of the lift fuel pump;at least one fuel injector in fluid communication with an outl

1. A direct injection fuel supply system for a vehicle, comprising: a lift fuel pump adapted to be in fluid communication with a supply of fuel;a positive displacement pump in fluid communication with and downstream of the lift fuel pump;at least one fuel injector in fluid communication with an outlet of the positive displacement pump via a high pressure fuel line;an accumulator assembly including an accumulator and a valve, the valve being in fluid communication with the high pressure fuel line and the at least one fuel injector, the accumulator fluidly coupled to the high pressure fuel line downstream of the positive displacement pump;wherein the valve is configured to be controlled to at least one of an open state providing fluid communication between the accumulator and the high pressure fuel line and a closed state blocking fluid communication between the accumulator and the high pressure fuel line;a one-way check valve disposed in the high pressure fuel line downstream of the positive displacement pump; anda high pressure branch line branching from the high pressure fuel line at a point downstream of the positive displacement pump and between the positive displacement pump and the at least one fuel injector; wherein the accumulator and the accumulator valve are disposed on the high pressure branch line, the accumulator valve being in fluid communication with the high pressure fuel line downstream of the check valve. 2. The fuel supply system of claim 1, wherein the accumulator valve is in fluid communication with the accumulator and the at least one fuel injector in a high pressure section of the direct injection fuel supply system. 3. The fuel supply system of claim 1, wherein the positive displacement pump is an engine driven positive displacement pump and the lift fuel pump is an electric fuel pump positioned in or proximate to a fuel tank. 4. The fuel supply system of claim 3, wherein the positive displacement pump is downstream of the lift fuel pump and configured to raise a pressure of fuel received from the lift pump at a low pressure to a high pressure in the high pressure fuel line. 5. The fuel supply system of claim 4, wherein the low pressure fuel is on an order of 4 bar and wherein the high pressure fuel is on an order of 200 bar for use with direct injection fuel injectors. 6. The fuel supply system of claim 1, further comprising: a pressure sensor in fluid communication with the high pressure fuel line proximate the at least one fuel injector; anda spill valve in fluid communication with a low pressure fuel supply line between the positive displacement pump and the lift fuel pump,wherein the spill valve and the valve of the accumulator assembly are solenoid valves. 7. The fuel supply system of claim 6, further comprising a controller in communication with the pressure sensor, accumulator valve, spill valve, the lift fuel pump and an engine, the controller configured to control a position of the accumulator valve and spill valve as well as operation of the lift fuel pump based at least on an operating state of the engine. 8. The fuel supply system of claim 7, wherein upon the controller determining the engine is operating in a deceleration state, the controller commands the accumulator valve to open upon which high pressure fuel from the positive displacement pump flows into the accumulator. 9. The fuel supply system of claim 7, further comprising: determining, at the controller, that an engine shutdown has been initiated;commanding, by the controller, the accumulator valve to open to harvest fuel pumped from the positive displacement pump as the engine coasts down to zero speed; andcommanding, by the controller, the accumulator valve to close upon determining the engine has fallen below a predetermined speed proximate zero speed to store pressurized fuel within the accumulator. 10. The fuel supply system of claim 9, further comprising: commanding, by the controller, the lift pump to an on state and the spill valve to open upon determining the engine is under a restart event such that fuel from the lift pump flows out of the spill valve prior to the positive displacement pump; andcommanding, by the controller, the accumulator valve to open thereby delivering high pressure fuel directly to the at least one injector for direct fuel injection associated with the restart event. 11. The fuel supply system of claim 10, wherein the high pressure fuel delivered to the at least one injector is solely from the accumulator and capable of providing an adequate supply of fuel to support the engine restart event. 12. A method for controlling a direct injection fuel supply system, comprising: monitoring, by a controller, an operating state of an engine;determining, by the controller, that the engine is operating in a deceleration state;commanding, by the controller, an accumulator valve fluidly coupled to an accumulator to open to allow pressurized fuel from a mechanically driven positive displacement pump to flow into the accumulator, the accumulator and the accumulator valve fluidly coupled to a high pressure fuel line that is in fluid communication with an output of the displacement pump, the high pressure fuel line coupled to at least one fuel injector, the accumulator and the accumulator valve fluidly coupled to the high pressure line at a point downstream of the positive displacement pump;commanding, by the controller, the accumulator valve to close at or proximate an end of the deceleration or shutdown state thereby storing pressurized fuel in the accumulator;wherein the accumulator valve is fluidly coupled to the high pressure fuel line in fluid communication with the at least one fuel injector and, when commanded to open by the controller, allows the accumulator to supply pressurized fuel to the at least one fuel injector;commanding, by the controller, a spill valve to open and the accumulator valve to open thereby supplying the pressurized fuel from the accumulator to the at least one fuel injector and not supply fuel from the displacement pump. 13. The method according to claim 12, further comprising: monitoring a pressure of the high pressure fuel line; andcommanding, by the controller, the accumulator valve to close and the spill valve to close upon determining the pressure in the high pressure fuel line falls below a predetermined nominal fuel injector pressure. 14. The method of claim 12, further comprising: monitoring pressure in the high pressure fuel line to sense pressure pulsations caused, at least in part, by the displacement pump and the at least one injector; andactively controlling the accumulator valve to attenuate the pressure pulsations. 15. The method of claim 14, wherein actively controlling the pressure pulsations includes: commanding, by the controller, the solenoid valve to open during a high pressure portion of the pressure pulsation to absorb an increase in pressure in the high pressure fuel line associated with the high pressure portion; andcommanding, by the controller, the solenoid valve to open during a low pressure portion of the pressure pulsation to return pressurized fuel from the accumulator to the high pressure fuel line, the returned pressurized fuel having a greater pressure than the pressure in the high pressure fuel line at the low pressure portion of the pressure pulsation. 16. A method for controlling a direct injection fuel supply system, comprising: monitoring, by a controller, an operating state of an engine;determining, by the controller, that the engine is operating in a deceleration state or a shutdown state;commanding, by the controller, an accumulator valve fluidly coupled to an accumulator to open to allow pressurized fuel from a mechanically driven positive displacement pump to flow into the accumulator, the accumulator and the accumulator valve fluidly coupled to a high pressure fuel line that is in fluid communication with an output of the displacement pump, the high pressure fuel line coupled to at least one fuel injector, the accumulator and the accumulator valve fluidly coupled to the high pressure line at a point downstream of the positive displacement pump; andcommanding, by the controller, the accumulator valve to close at or proximate an end of the deceleration or shutdown state thereby storing pressurized fuel in the accumulator;wherein the accumulator valve is fluidly coupled to the high pressure fuel line in fluid communication with the at least one fuel injector and, when commanded to open by the controller, allows the accumulator to supply pressurized fuel to the at least one fuel injector,determining that the engine is operating in a steady state outside of the deceleration state or shutdown state;comparing a pressure of the stored pressurized fuel in the accumulator with a predetermined nominal injection pressure; andcommanding, by the controller, the lift pump to an off state and the accumulator valve to open thereby supplying the stored pressurized fuel from the accumulator to the at least one fuel injector independent of the displacement pump. 17. The method of claim 16, further comprising: monitoring a pressure of the high pressure fuel line after the accumulator valve is commanded to open and, upon determining the pressure of the high pressure fuel line falls below a predetermined nominal injector pressure, commanding the accumulator valve to close and the lift pump to an on state.