Patent Application
20150020776
The present disclosure relates to a high-pressure fuel pump with dual outlets.
This section provides background information related to the present disclosure, which is not necessarily prior art.
Fuel delivery systems of direct injected engines often include a high-pressure fuel pump for pumping fuel to a first fuel rail and a second fuel rail. The fuel rails deliver fuel to a plurality of fuel injectors associated therewith. The fuel rails are often connected to the high-pressure pump with a Y-block, or a cross-over line extending between the fuel rails so as to connect the fuel rails in “series.” To attenuate fuel pulsations, orifices are added to fuel feed lines that deliver fuel to the fuel rails, and a pressure relief path to a fuel pump chamber is included. In spite of the orifices and the relief valve, fuel pulsations from one fuel rail often affect the pressure in the other fuel rail. For example, if a three lobe pump cam is used, there will be one pumping event for every two consecutive injection events (occurring on opposite fuel rails). This often leads to a pressure differential between the fuel rails, which is undesirable.
A fuel delivery system that provides pressure relief and isolates fuel rails from one another such that there is no pressure differential between them would therefore be desirable. This permits reduction in both fuel rail volume and pressure rise times. Isolating the fuel rails also reduces the number of joints between the high-pressure pump and the fuel rails, which simplifies assembly and reduces both assembly time and cost.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
The present teachings provide for a fuel delivery system including a high pressure fuel pump assembly. The assembly includes first and second output fuel paths each in communication with a fuel pump chamber. A main pressure relief fuel path is in communication with the fuel pump chamber and includes a pressure relief valve. A first relief fuel path is in communication with both the first output fuel path and the main pressure relief fuel path. A second relief fuel path is in communication with both the second output fuel path and the main pressure relief fuel path. The first and the second relief fuel paths are configured to restrict fuel flow therethrough between the first and the second output fuel paths.
The present teachings also provide for a fuel delivery system including a high pressure fuel pump assembly. The assembly includes a fuel pump chamber and a main fuel path in communication with the fuel pump chamber. A first output fuel path is in communication with the main fuel path and includes a first valve. A second output fuel path is in communication with the main fuel path and includes a second valve. A main pressure relief fuel path is in communication with the fuel pump chamber and includes a main relief valve. A first relief fuel path is in communication with both the first output fuel path and the main pressure relief fuel path. The first relief fuel path includes a first relief valve. The second relief fuel path is in communication with both the second output fuel path and the main pressure relief fuel path. The second relief fuel path includes a second relief valve. The first relief valve restricts fuel from flowing from the first output fuel path to the second output fuel path. The second relief valve restricts fuel from flowing from the second output fuel path to the first output fuel path.
The present teachings further provide for a fuel delivery system including a fuel pump, a main fuel path, a first output fuel path, and a second output fuel path. The fuel pump is housed within a fuel pump chamber. The main fuel path is in communication with the fuel pump chamber. The first output fuel path is in communication with the main fuel path. The second output fuel path is in communication with the main fuel path. A first fuel rail is configured to receive fuel from the first output fuel path and deliver fuel to a plurality of first fuel injectors. The second fuel rail is configured to receive fuel from the second output fuel path and deliver fuel to a plurality of second fuel injectors. A main pressure relief fuel path is in communication with the fuel pump chamber and includes a pressure relief valve. A first relief fuel path is in communication with both the first output fuel path and the main pressure relief fuel path. A second relief fuel path is in communication with both the second output fuel path and the main pressure relief fuel path. The first and the second relief fuel paths each provide an individual fuel path between the first and the second output fuel paths respectively. The main pressure relief fuel path includes the pressure relief valve. The first relief fuel path restricts fuel flow therethrough to the first output fuel path. The second relief fuel path restricts fuel flow therethrough to the second output fuel path.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
With initial reference to
The fuel pump housing 20 generally includes a fuel pump plunger 24 within a fuel pump chamber 26. The fuel pump plunger 24 can be any type of suitable pump to pump fuel to the first and second banks of fuel injectors 14 and 16. Extending from the fuel pump chamber 26 is a main output fuel line or path 30, which as illustrated extends from the fuel pump chamber 26, via housing 20, to the outlet assembly 22 connected to the fuel pump housing 20. The main output fuel path 30 is thus defined by both the fuel pump housing 20 and the outlet assembly 22.
Extending from the main output fuel path 30 is a first output fuel path 32. Also extending from the main output fuel path 30 is a second output fuel path 34. The first and second output fuel paths 32 and 34 may be defined by the outlet assembly 22 as illustrated, and may be defined by the fuel pump housing 20 as well.
As illustrated, the first output fuel path 32 extends to a first output 36 of the outlet assembly 22, where the first output fuel path 32 connects to a first fuel rail 38, which delivers fuel to the first bank of fuel injectors 14. Similarly, the second output fuel path 34 extends to a second output 40 of the outlet assembly 22. At the second output 40, the second output fuel path 34 transitions to a second fuel rail 42, which delivers fuel to the second bank of fuel injectors 16.
The first output fuel path 32 includes a first check valve 44. The second output fuel path 34 includes a second check valve 46, which can be substantially similar to the first check valve 44. The first and second check valves 44 and 46 can each be any suitable type of valve or device to permit fuel, which has been pumped by the fuel pump plunger 24 from the fuel pump chamber 26, to pass therethrough once the fuel has reached a target fuel pressure, such as 10 PSI for example. The first and the second check valves 44 and 46 can be located in the outlet assembly 22 or included in a portion 62 of the fuel pump housing 20.
A first relief fuel path 50 extends from the first output fuel path 32, and a second relief fuel path 52 extends from the second output fuel path 34. Both the first and the second relief fuel paths 50 and 52 extend to a main pressure relief fuel path 54, which extends back to the fuel pump chamber 26. The first and the second relief fuel paths 50 and 52 can be defined by the outlet assembly 22 and may connect with the main pressure relief fuel path 54 at the outlet assembly 22 as illustrated. Alternatively, one or both of the first and the second relief fuel paths 50 and 52 may extend to the fuel pump housing 20 to connect to the main pressure relief fuel path 54 at the fuel pump housing 20.
The first relief fuel path 50 includes a first relief check valve 56 and the second relief fuel path 52 includes a second relief check valve 58. The main pressure relief fuel path 54 includes a pressure relief valve 60, which can be a high pressure relief valve. The first and second relief check valves 56 and 58 can be any suitable valve or device to permit passage of fuel from the first and second output fuel paths 32 and 34 respectively upon reaching a predetermined pressure, such as about 10 PSI, in order to relieve pressure in the first and second output fuel paths 32 and 34, as well as the first and second fuel rails 38 and 42.
The first and second relief check valves 56 and 58 are each configured to restrict fuel flow therethrough to the second and first output fuel paths 34 and 32 respectively. Therefore, fuel from the first output fuel path 32 that has passed through the first relief check valve 56 is prevented from flowing to the second output fuel path 34 by the second relief check valve 58 and the first check valve 44. Similarly, the first relief check valve 56 restricts fuel that has passed through the second relief check valve 58 from flowing to the first output fuel path 32. The first and second relief check valves 56 and 58 thus prevent “cross-talk,” or fuel flow between the first and second banks of fuel injectors 14 and 16. The first and the second relief check valves 56 and 58 can be located in the outlet assembly 22 or included in a portion 64 of the fuel pump housing 20, regardless of where the first and the second check valves 44 and 46 are located.
The pressure relief valve 60 can be any suitable valve or device configured to permit fuel flow therethrough from the first or second relief fuel paths 50 and 52 once fuel has reached a predetermined pressure, such as 19 to 23 megapascals. The pressure relief valve 60 restricts fuel flow in the opposite direction. Fuel that has passed through the pressure relief valve 60 is returned to the fuel pump chamber 26 by way of the main pressure relief fuel path 54. The pressure relief valve 60 may be present in the fuel pump housing 20 as illustrated, or at any other suitable location, such as within the outlet assembly 22 or external to both the fuel pump housing 20 and the outlet assembly 22, as illustrated at reference number 60. The pressure relief valve 60 relieves pressure from the first and second fuel rails 38 and 42, and the first and the second relief check valves 56 and 58 prevent fuel from flowing between the first and second banks of fuel injectors 14 and 16.
Therefore, the first and second fuel rails 38 and 42, as well as the first and second banks of fuel injectors 14 and 16, are isolated such that fuel pressure pulses will not travel between the first and second fuel rails 38 and 42. There is no pressure differential between the first and second fuel rails 38 and 42, even when there are two injection events (or more) for one pumping event. This allows for the first and second fuel rails 38 and 42 to have a reduced volume, which can improve pressure rise times, reduce material costs, and improve reliability. The number of joints can also be reduced, because the fuel pump outlet assembly 22 acts as a T-joint.
With additional reference to
With additional reference to
The first relief fuel path 50 (
The first and second relief fuel paths 50 and 52 are connected by the main pressure relief fuel path 54, and specifically a first portion 54a thereof. The first portion 54a is generally semicircular and is formed within an inner surface 82 of the outlet assembly 22, which is mounted against the fuel pump housing 20. The first portion 54a of the main pressure relief fuel path 54 extends to, and slightly beyond, the second relief fuel path 52. A second portion 54b of the main pressure relief fuel path 54 extends from the first portion 54a at generally a right angle relative thereto and into the fuel pump housing 20, where the second portion 54b is in communication with the pressure relief valve 60. A third portion 54c of the main pressure relief fuel path 54 extends from the pressure relief valve 60 to the fuel pump chamber 26.
An exemplary method and manner of operation of the fuel delivery system 10 will now be described. Upon activation of the fuel pump plunger 24, fuel delivered to the fuel pump chamber 26 by way of the fuel inlet port 70 is pumped out from within the fuel pump chamber 26 through the main output fuel path 30, and to the first and second output fuel paths 32 and 34. If the fuel pressure is above the predetermined fuel pressure required to open the first and second check valves 44 and 46, fuel will flow through the first and second check valves 44 and 46 to the first fuel rail 38 and the second fuel rail 42. From the first fuel rail 38 fuel flows to the first bank of fuel injectors 14, and from the second fuel rail 42 fuel flows to the second bank of fuel injectors 16. The first and second relief check valves 56 and 58 will remain open as long as the fuel pressure within the first and second output fuel paths 32 and 34 is substantially equal and above the predetermined pressure required to keep the first and second relief check valves 56 and 58 in the open position. The pressure relief valve 60 will remain closed as long as the fuel pressure within the first and second output fuel paths 32 and 34 and the first and second relief fuel paths 50 and 52 is below the predetermined threshold required to open the pressure relief valve 60.
If the fuel pressure within the first output fuel path 32 is sufficiently greater than the fuel pressure within the second output fuel path 34, the first check valve 44 will close, the first relief check valve 56 will remain open, and the pressure relief valve 60 may open (depends on pressure level) to allow fuel to pass therethrough and into the fuel pump chamber 26 by way of the main pressure relief fuel path 54. To prevent high-pressure fuel pulses from passing from the first and/or second relief fuel paths 50/54 to the second output fuel path 34, the second relief check valve 58 will close to prevent fuel from flowing therethrough to the second output fuel path 34. Closure of the second check valve 46 also restricts fuel from flowing to the second output fuel path 34 from the first output fuel path 32. With respect to the second check valve 46, it will remain open unless the fuel pressure therein is greater than the predetermined pressure required to close the second check valve 46.
If the fuel pressure of the second output fuel path 34 becomes sufficiently greater than the fuel pressure of the first output fuel path 32, the second relief check valve 58 will close to isolate the first bank of fuel injectors 14 from the second bank of fuel injectors 16. The second relief check valve 58 will open to provide a relieve path from the second output fuel path 34 to the main pressure relief fuel path 54. The pressure relief valve 60 may remain open (depends on pressure level) to permit highly pressurized fuel to pass from the second output fuel path 34 and the second bank of fuel injectors 16 back to the fuel pump chamber 26. The first check valve 44 will close to further isolate the first bank of fuel injectors 14 from the second bank of fuel injectors 16. The first check valve 44 will close if the fuel pressure within the first fuel rail 38 is greater than the fuel pressure of the main output fuel path 30.
With additional reference to
With additional reference to
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
