Patent Application
20100176222
The present disclosure relates to engine fuel systems, and more specifically to fuel injectors.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Pressure actuated fuel injectors may include a pressurized fuel supply used to open and close an injection nozzle opening. The injector may include an actuation member and a valve mechanism to selective open and close a leakage path between low pressure and high pressure regions of the injector. Opening the leakage path may reduce a closing biasing force applied to an injection valve to open the injection nozzle opening. When the leakage path is closed, the injection valve may be displaced to close the injection nozzle opening. Friction forces between the actuation member and the valve mechanism may provide difficulties in maintaining the valve mechanism in a fully seating condition when an injection event is completed.
An engine assembly may include a fuel injector having a housing, an actuation mechanism, and a valve member. The housing may define a high pressure region, a low pressure region, a longitudinal bore, and a valve seat having an aperture extending therethrough. The actuation member may be disposed within the longitudinal bore and may include a first axial end surface. The valve mechanism may be axially displaceable between first and second positions. The valve mechanism may abut the valve seat in the first position to seal the aperture from communication with the low pressure region and may be displaced from the valve seat in the second position to provide communication between the low and high pressure regions through the aperture. The valve mechanism may include a second axial end surface abutting the first axial end surface. The first and second axial end surfaces may define an outer contact perimeter and a chamber within the outer contact perimeter. A radial surface area defined by the chamber formed by the first and second axial end surfaces may be at least 25 percent of a radial surface area defined within the outer contact perimeter.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples 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 illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
Referring to
The fuel system 14 may include a fuel pump 22, a fuel tank 24, a fuel rail 26, fuel injectors 28, a main fuel supply line 30, secondary fuel supply lines 32 and fuel return lines 34. The fuel pump 22 may be in communication with the fuel tank 24 and may provide a pressurized fuel supply to the fuel rail 26 via the main fuel supply line 30. The fuel rail 26 may provide the pressurized fuel to injectors 28 via the secondary fuel supply lines 32. The fuel rail 26 may include a pressure regulating valve 36 that regulates fuel pressure within the fuel rail 26 by returning excess fuel to the fuel tank 24 via a return line 38.
The fuel injectors 28 may each include a solenoid valve mechanism 40 in communication with the control module 16. In the present non-limiting example, the fuel injectors 28 may form direct injection fuel injectors where fuel is injected directly into the cylinders 20. The fuel injectors 28 may return excess fuel to the fuel tank 24 via the fuel return lines 34.
With reference to
With reference to
As seen in
The first biasing member 80 may include a compression spring and may be engaged with the main body portion 48 of the housing 42 and the sleeve 78. The force applied to the sleeve 78 by the first biasing member 80 and the pressurized fuel within the high pressure chamber acting on the second end 90 of the plunger 76 may normally bias the first valve member 74 into the closed position (seen in
Referring to
The valve mechanism 96 may be radially and axially displaceable relative to the actuation member 94 and may include a valve holder 104 and a second valve member 106. A radial clearance may exist between the guide member 52 and the valve holder 104 to accommodate assembly tolerances. The valve holder 104 may include the first end 108 of the valve mechanism 96 and may further include a second end 110 housing the second valve member 106. For example, the second end 110 may include a recess 112 housing the second valve member 106. By way of non-limiting example, the second valve member 106 may include a ball and the recess 112 may include a shape generally conforming to the second valve member 106, such as a semi-spherical recess or a conical recess. While described as two separate parts, it is understood that the valve holder 104 and the second valve member 106 may be fixed to one another to form a single part.
As discussed above, the first end 102 of the actuation member 94 may abut the first end 108 of the valve mechanism 96. The first end 102 of the actuation member 94 may form a first axial end surface 114 and the first end 108 of the valve mechanism 96 may form a second axial end surface 116. The abutment between first and second axial end surfaces 114, 116 may define an outer contact perimeter 118. The first and second axial end surfaces 114, 116 may cooperate to define a chamber 120 between the first and second axial end surfaces 114, 116. The chamber 120 may provide a spacing between central portions of the first and second axial end surfaces 114, 116 located radially within the outer contact perimeter 118. The chamber 120 may form a radial surface area at least twenty-five percent of the radial surface area located within the outer contact perimeter 118. More specifically, in the present non-limiting example, the chamber 120 may form a radial surface area between fifty and ninety-five percent of the radial surface area located within the outer contact perimeter 118.
In the present non-limiting example (seen in
The radial surface area (A11) formed by the engagement between the first and second axial end surfaces 114,116 may be defined as the area between the inner and outer contact diameters (D1i, D1o) and may form an annular contact region between the first and second axial end surfaces 114, 116. The radial surface area (A11) may be at least twenty-five percent of a radial surface area (A12) defined by the outer contact diameter (D1o). More specifically, the radial surface area (A11) may be between fifty and ninety-five percent of the radial surface area (A12).
An alternate actuation member 194 and valve mechanism 196 are shown in
The radial surface area (A21) formed by the engagement between the first and second axial end surfaces 214, 216 may be defined as the area between the inner and outer contact diameters (D2i, D2o) and may form an annular contact region between the first and second axial end surfaces 214, 216. The radial surface area (A21) may be at least twenty-five percent of a radial surface area (A22) defined by the outer contact diameter (D2o). More specifically, the radial surface area (A21) may be between fifty and ninety-five percent of the radial surface area (A21).
An alternate actuation member 294 and valve mechanism 296 are shown in
The radial surface area (A31) formed by the engagement between the first and second axial end surfaces 314, 316 may be defined as the area between the inner and outer contact diameters (D3i, D3o) and may form an annular contact region between the first and second axial end surfaces 314, 316. The radial surface area (A31) may be at least twenty-five percent of a radial surface area (A32) defined by the outer contact diameter (D3o). More specifically, the radial surface area (A31) may be between fifty and ninety-five percent of the radial surface area (A32).
The fuel injector 28 may be a pressure actuated fuel injector, where fuel pressure opens the nozzle opening 56. During operation, the control module 16 may selectively command opening and closing of the nozzle opening 56 using the solenoid valve mechanisms 40. When injection is desired, the solenoid valve 40 may displace the actuation member 94 in a direction axially outward from the valve seat 50 against the force of the basing member 98. Pressurized fuel within the biasing chamber 91 may force the valve mechanism 96 axially outward from the valve seat 50 once the actuation member 94 is displaced, providing a leak path between the biasing chamber 91 and low pressure fuel chamber 64. The leakage may provide a pressure drop in the biasing fuel chamber 91, reducing a biasing force applied to the second end 90 of the plunger 76 by the fuel within the biasing chamber 91.
The reduced biasing force applied by the fuel within the biasing chamber 91 may provide for displacement of the first valve member 74 and opening of the nozzle opening 56. More specifically, the force applied to the radial surface 86 by fuel within the recess 92 may be sufficient to overcome the force applied by the biasing member 80 and the reduced force applied to the second end 90 of the plunger 76 by the fuel within the biasing chamber 91, resulting in the displacement of the first valve member 74.
After a desired injection event is completed, the solenoid valve 40 may be de-energized and the biasing member 98 may return the valve mechanism 96 to a closed condition. The various examples of offset central surfaces created by the chambers 120, 220, 320 may provide for a complete seating of the second valve member 106 on the valve seat 50. Further, it is understood that while the injector 28 has been described as providing fuel to an engine cylinder, other applications may use the present teachings. For example, the fuel injector 28 may alternatively or additionally be used to inject fuel into an exhaust aftertreatment system (not shown).
