High pressure fuel pumps with mechanical pressure regulation
Methods are provided for operating a high pressure fuel pump to maintain one or more selectable, mechanically-regulated pressures. To reduce the cost and complexity associated with a fuel system that involves both port and direct fuel injection, a fuel and pump system is needed that removes complicated electronic control without degrading pump and engine performance. High pressure fuel pumps, associated systems, and methods are provided that involve adding one or more pressure relief valves and solenoid valves in order to maintain one or more discrete, substantially constant pressures of the high pressure fuel pumps and attached direct injection fuel rails.
1. A method, comprising:
during a first high pressure fuel pump operating mode, regulating a first fuel rail pressure via a first pressure relief valve; and
during a second high pressure fuel pump operating mode, regulating a second fuel rail pressure via a second pressure relief valve that is in parallel with the first pressure relief valve and separated by a solenoid valve to direct fuel backflow to the first or second pressure relief valve, wherein a fuel rail pressure sensor is not provided on a direct injection fuel rail fluidly coupled to a high pressure fuel pump.
2. The method of claim 1 , wherein switching between the first and second high pressure fuel pump operating modes includes opening or closing of the solenoid valve.
3. The method of claim 1 , wherein the high pressure fuel pump is not connected to an external electronic controller.
4. The method of claim 1 , further comprising a third pressure relief valve positioned in parallel with the first and second pressure relief valves, the third pressure relief valve configured to regulate a third fuel rail pressure during a third high pressure fuel pump operating mode.
5. The method of claim 4 , further comprising an upstream solenoid valve positioned to direct fuel backflow to either the second or third pressure relief valve.
6. The method of claim 5 , wherein switching between the first, second, and third high pressure fuel pump operating modes includes opening or closing of the solenoid valve and upstream solenoid valve.
7. The method of claim 6 , further comprising a restriction for adjusting fuel rail pressure as an engine speed increases or decreases.
8. A fuel system, comprising:
a port fuel injection system including a port fuel injection fuel rail, the port fuel injection system operating during a first engine operating mode;
a direct injection system including a direct injection fuel rail with no fuel rail pressure sensor, the direct injection system operating during a second engine operating mode;
a high pressure fuel pump fluidly coupled to the direct injection fuel rail, the high pressure fuel pump including no electrical connection to a controller;
an inlet check valve located upstream of the high pressure fuel pump;
a first pressure relief valve in parallel with the inlet check valve;
a second pressure relief valve in parallel with the first pressure relief valve; and
a solenoid valve configured to switch fuel backflow between the first and second pressure relief valves.
9. The fuel system of claim 8 , wherein the first engine operating mode is a low power operating mode and the second engine operating mode is a high power operating mode.
10. The fuel system of claim 8 , further comprising a fuel rail pressure relief valve located in between the direct injection fuel rail and high pressure fuel pump.
11. The fuel system of claim 10 , further comprising a restriction in series with the fuel rail pressure relief valve for adjusting direct injection fuel rail pressure as an engine speed increases or decreases.
12. The fuel system of claim 8 , wherein the high pressure fuel pump further comprises an outlet check valve located on an outlet of the high pressure fuel pump.
13. The fuel system of claim 8 , further comprising a third pressure relief valve positioned in parallel with the first and second pressure relief valves.
14. The fuel system of claim 13 , further comprising an upstream solenoid valve configured to switch fuel backflow between the second and third pressure relief valves.
15. A method for mechanical pressure regulation of a high pressure fuel pump, comprising:
selectively regulating a compression chamber pressure of the high pressure fuel pump to one or more discrete, substantially constant pressures, the high pressure fuel pump not including a solenoid activated check valve;
controlling fuel flow while providing no connection between the high pressure fuel pump and a controller; and
preventing a pressure increase past an upper pressure threshold by providing a fuel rail pressure relief valve in between a direct injection fuel rail and the high pressure fuel pump, wherein no fuel rail pressure sensor is positioned on the direct injection fuel rail.
16. The method of claim 15 , wherein the high pressure fuel pump includes an inlet check valve located at an inlet of the pump and an outlet check valve located on an outlet of the pump.
17. The method of claim 15 , further comprising a restriction in series with the fuel rail pressure relief valve for adjusting fuel rail pressure as an engine speed increases or decreases.
18. The method of claim 15 , wherein the controller does not provide a wired connection or control of the high pressure fuel pump.