Cross-Reference to Related Application:

[00001] The present application claims the benefit of the filing date of U.S. Provisional Application No. 63/240,557 filed on September 3, 2021, which is incorporated herein by reference.

TECHNICAL FIELD

[00002] The present application relates generally to a camshaft, and more particularly to profiled journals on the camshaft.

BACKGROUND

[00003] Common rail direct fuel injection is commonly used on diesel engines. The common rail direct fuel system includes a low pressure pump operatively connected and attached to a high pressure pump. The low pressure pump feeds or provides fuel to the high pressure pump that thereafter creates high pressure and fueling requirements. A camshaft is positioned inside of the high pressure fuel pump to increase the pressure of the fuel. The pressurized fuel is then sent to a rail that balances out the pressure per the number of connected fuel injectors, which spray the fuel into the engine.

[00004] A camshaft includes a front bearing journal and a rear bearing journal. A front bushing or flanged bi-metal bearing includes a thrust flange and a cylinder, wherein the bearing is positioned on the front bearing journal. A rear bushing or bearing includes a thrust flange and a cylinder, wherein the bearing is positioned on the rear bearing journal. The camshaft with the assembled front bearing and the assembled rear bearing is positioned into the pump housing of the high pressure fuel pump. The camshaft operates or rotates within the front and rear bi-metal bearings. Operation of the camshaft results in heat being generated over a period of time.

[00005] Therefore, further contributions in this area of technology are needed to improve the durability of front and rear bearing journals of camshafts. Therefore, there remains a significant need for the apparatuses and systems disclosed herein. SUMMARY

[00006] This summary is provided to introduce a selection of concepts that are further described below in the illustrative embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

[00007] According to one embodiment of the present disclosure, a camshaft for use with a fuel pump, the camshaft comprising: a camshaft body having a length that spans along a longitudinal axis of the camshaft body; a front bearing journal; and a rear bearing journal opposite the front bearing journal, wherein at least one of the front bearing journal and the rear bearing journal has an asymmetric outer profile that extends along the longitudinal axis.

[00008] In one example of this embodiment, each of the front and the rear bearing journals have the asymmetric outer profile.

[00009] In a further example of this embodiment, the asymmetric outer profile of the front bearing journal is different than the asymmetric outer profile of the rear bearing journal. [00010] In a further example of this embodiment, the asymmetric outer profile of the front bearing journal mirrors the asymmetric outer profile of the rear bearing journal.

[00011] In any of the above embodiments, at least one of the front bearing journal and/or the rear bearing journal has a diameter at one location along the longitudinal length that is different than a diameter at another location along the longitudinal length.

[00012] In the above embodiments, the asymmetric outer profile of the front bearing journal has a front outer diameter and the asymmetric outer profile of the rear bearing journal has a rear outer diameter, the front outer diameter is different than the rear outer diameter.

[00013] In any of the above embodiments, the asymmetric outer profile includes a flat portion positioned between a first tapered portion and a second tapered portion.

[00014] In the above embodiment, the first tapered portion has a different slope than the second tapered portion.

[00015] In any of the above embodiments, the asymmetric outer profile includes a radial dimension measured relative to the longitudinal axis of the camshaft body, wherein the radial dimension is independent of the diameter. [00016] In any of the above embodiments, the asymmetric outer profile corresponds to a distorted interior bearing surface of a first bearing assembled onto the at least one of the front and/or the rear bearing journals after operation of the camshaft.

[00017] In the above embodiment, the asymmetric outer profile of the other one of the front and/or rear bearing journals corresponds to a distorted interior bearing surface of a second bearing assembled onto the other of the front and/or the rear bearing journals.

[00018] In another embodiment, a system that includes a high pressure fuel pump and the camshaft of any one of the above aspects assembled with the high pressure fuel pump.

[00019] In such an embodiment, further comprising: a low pressure fuel pump operatively connected to the high pressure fuel pump.

BRIEF DESCRIPTION OF THE DRAWINGS

[00020] The concepts described herein are illustrative by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale. Where considered appropriate, references labels have been repeated among the figures to indicate corresponding or analogous elements.

[00021] Fig. l is a side view of a camshaft of the present disclosure.

[00022] Fig. 2 is a partial side view of a front bearing journal of Fig. 1 of the present disclosure.

[00023] Fig. 3 is a partial side view of a rear bearing journal of Fig. 1 of the present disclosure.

[00024] Fig. 4 is a cross-sectional view of a camshaft of Fig. 1 of the present disclosure.

[00025] Fig. 5 is a schematic side view of an exemplary asymmetric outer profile of the front bearing journal of Fig. 2 of the present disclosure.

[00026] Fig. 6 is a perspective view of one embodiment of a bearing that can be assembled with the camshaft of Fig. 1 of the present disclosure.

[00027] Fig. 7 is an enlarged cross-sectional view of the rear bearing journal of the camshaft of Fig. 1 of the present disclosure partially assembled with a distorted bearing. [00028] Fig. 8 is a perspective view of a common rail direct fuel system.

[00029] Fig. 9 is a cross-sectional view of a fuel pump of Fig. 8 and the camshaft of Fig. 1 of the present disclosure assembled with a bearing.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[00031] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, any alterations and further modifications in the illustrated embodiments, and any further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated herein.

[00032] The embodiments described herein can provide systems and apparatuses that include a camshaft having a front bearing journal with an asymmetric outer profile of an outer surface or camshaft mating surface that accommodates the non-uniform thermal growth or bore distortion of a bearing during operation of the camshaft with a bearing assembled thereon. The camshaft includes a rear bearing journal with an asymmetric outer profile of an outer surface that accommodates the non-uniform thermal growth or bore distortion of a bearing during operation of the camshaft with a bearing assembled thereon. The asymmetric outer profile of the front and/or rear bearing journals can be used with bearings or bushings in any system that requires a camshaft. Some non-limiting examples of systems include a diesel or internal combustion engine fuel pump, a crankshaft of an engine, a camshaft of an engine’s valvetrain, or any other journal surfaces that interact with a bearing.

[00033] The asymmetric front bearing journal and/or asymmetric rear bearing journal of the camshaft can accommodate non-uniform thermal growth and/or bore distortion of flanged bearings that are assembled with the front and rear bearing journals. The front and rear bearing journals of the camshaft are “profiled” with a complex geometry to accommodate the non- uniform thermal growth or bore distortion of the flanged bearings. In some embodiments, only one of the front and rear bearing journals of the camshaft are profiled while the other one of the front and rear bearing journals have a round profile. In some embodiments, the profile of the front bearing journal mirrors the profile of the rear bearing journal. The front and/or rear bearing journals have a variable diameter over portions of the front and/or rear journals such that each of an outer diameter that is measured at different locations along a length of the front and/or rear journals will be different from each other. The front and/or rear bearing journals have an asymmetric outer profile. The asymmetric outer profile includes a radial dimension measured relative to the longitudinal axis of the camshaft and a variable diameter that is perpendicular to the longitudinal axis. The change in radial dimensions and variable diameters are independent of each other. Beneficially the asymmetric outer profile of the front and/or rear bearing journals accommodates the non-uniform thermal growth (i.e. bore distortion) of the bearings, prevents overheating and deformation of the bearings assembled with the front and/or rear bearing journals, and reduces friction and therefore improves efficiency.

[00034] Turning now to the present application with reference to Figs. 1-5, a camshaft 100 is illustrated. The camshaft 100 can be used with a fuel pump for an engine. The camshaft 100 has a body 101. The body 101 has a length, L, that spans along a longitudinal axis LA of the camshaft 100. The camshaft 100 includes a front bearing journal 102 and a rear bearing journal 104. The front bearing journal 102 is opposite a rear bearing journal 104. The front bearing journal 102 has an asymmetric outer profile 106 and/or the rear bearing journal 104 has an asymmetric outer profile 108 that extends along the longitudinal axis LA.

[00035] The front bearing journal 102 has a length LI that spans along the longitudinal axis LA. The length LI represents a bearing contact length and is the same or substantially the same length as an interior bearing surface 702 of a bearing 700 when the front bearing journal 102 is assembled with the bearing 700 that is illustrated in Fig. 6.

[00036] Referring to Fig. 2, the front bearing journal 102 includes an asymmetric outer profile 106 that spans along the length LI and the longitudinal axis LA of the camshaft 100. The asymmetric outer profile 106 includes a substantially flat portion L2 positioned between a first tapered portion L3 and a second tapered portion L4. The substantially flat portion L2, first tapered portion L3, and the second tapered portion L4 refer to the longitudinal outer profile of the camshaft 100 from a side view and illustrate a change in cross-sectional height over the length of each of these portions. The length as measured along the longitudinal axis LA of each of the substantially flat portion L2, the first tapered portion L3, and the second tapered portion L4 may be the same or may vary relative to each other. In the illustrated embodiment of Fig. 2, the substantially flat portion L2 has a longer length than the second tapered portion L4, and the second tapered portion L4 has a longer length than the first tapered portion L3. In other embodiments the lengths of flat portion L2, first tapered portion L3, and second tapered portion L4 may be different such that the lengths are all equal or the first tapered portion L3 is longer than the second tapered portion L4. [00037] Preferably, the first and the second tapered portions L3 and L4 of the asymmetric outer profile 106 have a curved and/or sloped longitudinal outer profile to generally align with a distorted profile of an interior bearing surface 702’ of the bearing 700’ (Fig. 7) wherein the interior bearing surface 702’ accounts for distortion to the original shape of the interior bearing surface 702 from operation of the camshaft 100 over a period of time wherein heat is generated that can distort the interior bearing surface 702 of the bearing 700. In the illustrated embodiment, the asymmetric outer profile 106 has an asymmetric outer profile that extends along the longitudinal axis LA such that the first tapered portion L3 has a different slope and/or radius than the second tapered portion L4. The asymmetric outer profile 106 has a generally convex shape relative to the longitudinal axis LA of the camshaft 100. In the illustrated embodiment in Fig. 2, the first tapered portion L3 has a radius R3 and the second tapered portion L4 has a radius R4 wherein radius R3 is larger than radius R4 wherein radius R3 and radius R4 are measured relative to the longitudinal axis LA of the camshaft 100. In other embodiments the slope and/or radii R3 and R4 may be the same for the first tapered portion L3 and the second tapered portion L4. In yet other embodiments, the radius R4 may be larger than radius R3 for the first tapered portion L3 and the second tapered portion L4.

[00038] The front bearing journal 102 has an outer diameter that varies along the length LI and the longitudinal axis LA of the camshaft 100. The first tapered portion L3 has a first outer diameter D3 varies along the length of the first tapered portion L3 such that each of the outer diameters measured at locations along the length LI will be different from each other. In the illustrated embodiment, the first outer diameter D3 is a smaller diameter at a front end 120. The first outer diameter D3 is a larger diameter at a second location 122 that corresponds to an end of the substantially flat portion L2. The first outer diameter D3 as measured at locations from the front end 120 to the second location 122 will increase. The outer diameter D2 is substantially constant as measured at various locations over the length of the substantially flat portion L2 that spans from the second location 122 to a third location 124. The outer diameter D2 is a larger diameter as compared to the first outer diameter D3 at the front end 120. The second tapered portion L4 has a second outer diameter D4 that varies along the length of the second tapered portion L4 such that each of the outer diameters measured at locations along the length L4 will be different from each other. The second outer diameter D4 is a larger diameter at the third location 124 that corresponds to the outer diameter D2 of the substantially flat portion L2. The second outer diameter D4 is a smaller diameter at a rear end 126. The second outer diameter D4 as measured at locations from the third location 124 to the rear end 126 will decrease.

[00039] The rear bearing journal 104 has a length L10 that spans along the longitudinal axis LA. The length L10 represents a bearing contact length and is the same or substantially the same length as the interior bearing surface 702 when the rear bearing journal 104 is assembled with the bearing 700.

[00040] Referring to Fig. 3, the rear bearing journal 104 includes an asymmetric outer profile 108 that spans along the length L10 and the longitudinal axis LA of the camshaft 100. The asymmetric outer profile 108 includes a substantially flat portion L12 positioned between a first tapered portion L13 and a second tapered portion L14. The substantially flat portion L12, first tapered portion LI 3, and the second tapered portion L14 refer to the longitudinal outer profile of the camshaft 100 from a side view and illustrate a change in cross-sectional height over the length of each of these portions. The length as measured along the longitudinal axis LA of each of the substantially flat portion L12, the first tapered portion L13, and the second tapered portion L14 may be the same or may vary relative to each other. In the illustrated embodiment of Fig. 3, the substantially flat portion L12 has a longer length than the second tapered portion L14, and the first tapered portion L13 has a longer length than the second tapered portion L14. In other embodiments the lengths of flat portion L12, first tapered portion L13, and second tapered portion L14 may be different such that the lengths are all equal or the second tapered portion L14 is longer than the first tapered portion L13.

[00041] Preferably, the first and the second tapered portions L13 and L14 of the asymmetric outer profile 108 have a curved and/or sloped longitudinal outer profile to generally align with a distorted profile of an interior bearing surface 702’ of the bearing 700’ (Fig. 7) wherein the interior bearing surface 702’ accounts for distortion to the original shape of the interior bearing surface 702 from operation of the camshaft 100 over a period of time wherein heat is generated that can distort the interior bearing surface 702 of the bearing 700. In the illustrated embodiment, the asymmetric outer profile 108 has an asymmetric outer profile that extends along the longitudinal axis LA such that the first tapered portion L13 has a different slope and/or radius than the second tapered portion L14. The asymmetric outer profile 108 has a generally convex shape relative to the longitudinal axis LA of the camshaft 100. In the illustrated embodiment in Fig. 3, the first tapered portion L13 has a radius R13 and the second tapered portion L14 has a radius R14 wherein radius R14 is larger than radius R13 and radii R13 and R14 are measured relative to the longitudinal axis LA of the camshaft 100. In other embodiments the slope and/or radii R13 and R14 may be the same for the first tapered portion L13 and the second tapered portion L14. In yet other embodiments, the radius R13 may be larger than radius R14 for the first tapered portion L13 and the second tapered portion L14. [00042] The rear bearing journal 104 has an outer diameter that varies along the length L10 and the longitudinal axis LA of the camshaft 100. The first tapered portion L13 has a first outer diameter D13 varies along the length of the first tapered portion LI 3 such that each of the outer diameters measured at locations along the length LI 3 will be different from each other. In the illustrated embodiment, the first outer diameter D13 is a smaller diameter at a front end 220. The first outer diameter D13 is a larger diameter at a second location 222 that corresponds to a first end of the substantially flat portion L12. The first outer diameter D13 as measured at locations from the front end 220 to the second location 222 will increase. The outer diameter D12 is substantially constant as measured at various locations over the length of the substantially flat portion L12 that spans from the second location 222 to a third location 224. The outer diameter D12 is a larger diameter as compared to the first outer diameter D13 at the front end 220. The second tapered portion L14 has a second outer diameter D14 that varies along the length of the second tapered portion L14 such that each of the outer diameters measured at locations along the length L14 will be different from each other. The second outer diameter D14 is a larger diameter at the third location 224 that corresponds to the outer diameter D12 of the substantially flat portion L12. The second outer diameter D14 is a smaller diameter at a rear end 226. The second outer diameter D14 as measured at locations from the third location 224 to the rear end 226 will decrease.

[00043] The rear bearing journal 104 includes the asymmetric outer profile 108 that spans along the length L10 and the longitudinal axis LA of the camshaft 100. The asymmetric outer profile 108 is configured to mate with the interior bearing surface 702’ of the bearing 700’ wherein the interior bearing surface 702’ accounts for distortion to the interior bearing surface 702 from operation of the camshaft 100. The clearance between the asymmetric outer profile 108 and the interior bearing surface 702’ when the rear bearing journal 104 is assembled with the bearing 700’ accounts for the interior bearing surface 702’ being distorted. The rear bearing journal 104 is illustrated in Fig. 7. For clarity, the bearing 700’ is the bearing 700 that has undergone distortion or deformation due to operation of the camshaft 100 over a period of time. The interior bearing surface 702’ is the interior bearing surface 702 that has become distorted due to operation of the camshaft 100 over a period of time.

[00044] In the illustrated embodiment, the asymmetric outer profile 106 of the front bearing journal 102 is a mirrored profile relative to the asymmetric outer profile 108 of the rear bearing journal 104. In other embodiments, the asymmetric outer profile 106 is the same profile as the asymmetric outer profile 108. Optionally, the asymmetric outer profile 106 is different than the asymmetric outer profile 108. The asymmetric outer profile 106 and 108 include a convex shape relative to the longitudinal axis LA of the camshaft 100.

[00045] Illustrated in Fig. 6 is one embodiment of a bearing 700 that can be assembled with either or both of the front and rear bearing journals 102 and 104. The bearing 700 includes an interior bearing surface 702 that interacts or mates with the front and rear bearing journals 102 and 104. The bearing 700 includes a thrust bearing 704 adjacent the interior bearing surface 702. While a thrust bearing is provided as an example, any suitable types or embodiments of a bearing can be used with the front and rear bearing journals 102 and 104.

[00046] The asymmetric outer profile 110 is configured to mate with the interior bearing surface 702’ of the bearing 700’ (Fig. 7) wherein the interior bearing surface 702’ accounts for distortion to the original shape of the interior bearing surface 702 from operation of the camshaft 100 over a period of time. The clearance between the asymmetric outer profile 110 and the interior bearing surface 702’ when the rear bearing journal 104 is assembled with the bearing 700 accounts for distortion of the interior bearing surface 702’ from the non-uniform thermal growth of the rear bearing journal 104 during operation of the camshaft 100. The rear bearing journal 104 is illustrated in Fig. 7 however the front bearing journal 102 is similar to the rear bearing journal 104, except for the orientation of the bearing 700 relative to the front bearing journal 102 and the front bearing journal 102 may have a different profile. For clarity, the bearing 700’ is the bearing 700 after bearing 700 is distorted or deformed due to operation of the camshaft 100 over a period of time. Similarly, the interior bearing surface 702’ is the interior bearing surface 702 that was distorted due to operation of the camshaft 100 over a period of time. [00047] As shown in Figs. 8 and 9, a common rail direct fuel system 800 includes a high pressure pump 802 and the camshaft 100 assembled therein. The high pressure pump 802 can be operatively connected with a low pressure pump 804 as part of a common rail direct fuel system 800. The low pressure pump 804 feeds or provides fuel to the high pressure pump 802 that thereafter creates high pressure and fueling requirements. The camshaft 100 is positioned inside of the high pressure fuel pump 802 to increase the pressure of the fuel. The pressurized fuel is then sent to a rail 806 that balances out the pressure per the number of connected fuel injectors 808, which spray the fuel into an engine (not illustrated).

[00048] The asymmetric outer profiles 106 and/or 108 of the front and/or rear bearing journals 102 and 104 are used with bearings or bushings 700 in the system 800 or other engine systems that may require the camshaft 100. The asymmetric outer profiles 106 and/or 108 of the front and/or rear bearing journals 102 and 104 assist in maintaining camshaft rotation within the bearings or bushings 700 such that a clearance exists between the front and/or rear bearing journals 102 and 104 and the interior bearing surface 702’ to account for possible distortion to the original shape of the interior bearing surface 702 from operation of the camshaft 100 over a period of time wherein heat is generated that can distort the interior bearing surface 702 of the bearing 700.

[00049] Some non-limiting examples of systems that include the asymmetric outer profiles 106 and/or 108 of the front and/or rear bearing journals 102 and 104 of camshaft 100 are a diesel or internal combustion engine fuel pump, a crankshaft of an engine, a camshaft of an engine’s valvetrain, or any other journal surfaces that interact with a bearing.

[00050] As is evident from the figures and text presented above, a variety of aspects of the present disclosure are contemplated.

[00051] Various aspects of the present application are contemplated. According to one aspect, a camshaft for use with a fuel pump, the camshaft comprising: a camshaft body having a length that spans along a longitudinal axis of the camshaft body; a front bearing journal; and a rear bearing journal opposite the front bearing journal, wherein at least one of the front bearing journal and the rear bearing journal has an asymmetric outer profile that extends along the longitudinal axis.

[00052] In the above aspect, each of the front and the rear bearing journals have the asymmetric outer profile.

[00053] In the above aspect, the asymmetric outer profile of the front bearing journal is different than the asymmetric outer profile of the rear bearing journal. [00054] In the above aspect, the asymmetric outer profile of the front bearing journal mirrors the asymmetric outer profile of the rear bearing journal.

[00055] In any of the above aspects, at least one of the front bearing journal and/or the rear bearing journal has a diameter at one location along the longitudinal length that is different than a diameter at another location along the longitudinal length.

[00056] In the above aspect, the asymmetric outer profile of the front bearing journal has a front outer diameter and the asymmetric outer profile of the rear bearing journal has a rear outer diameter, the front outer diameter is different than the rear outer diameter.

[00057] In any of the above aspects, the asymmetric outer profile includes a flat portion positioned between a first tapered portion and a second tapered portion.

[00058] In the above aspect, the first tapered portion has a different slope than the second tapered portion.

[00059] In any of the above aspects, the asymmetric outer profile includes a radial dimension measured relative to the longitudinal axis of the camshaft body, wherein the radial dimension is independent of the diameter.

[00060] In any of the above aspects, the asymmetric outer profile corresponds to a distorted interior bearing surface of a first bearing assembled onto the at least one of the front and/or the rear bearing journals after operation of the camshaft.

[00061] In the above aspect, the asymmetric outer profile of the other one of the front and/or rear bearing journals corresponds to a distorted interior bearing surface of a second bearing assembled onto the other of the front and/or the rear bearing journals.

[00062] In another aspect, a system that includes a high pressure fuel pump and the camshaft of any one of the above aspects assembled with the high pressure fuel pump.

[00063] In such an aspect, further comprising: a low pressure fuel pump operatively connected to the high pressure fuel pump.

[00064] In the above description, certain relative terms may be used such as “up,” “down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” “proximal,” “distal,” and the like.

These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But, these terms are not intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same object. [00065] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. Similarly, the use of the term “implementation” means an implementation having a particular feature, structure, or characteristic described in connection with one or more embodiments of the present disclosure, however, absent an express correlation to indicate otherwise, an implementation may be associated with one or more embodiments.

[00066] The described features, structures, advantages, and/or characteristics of the subject matter of the present disclosure may be combined in any suitable manner in one or more embodiments and/or implementations. In the following description, numerous specific details are provided to impart a thorough understanding of embodiments of the subject matter of the present disclosure. One skilled in the relevant art will recognize that the subject matter of the present disclosure may be practiced without one or more of the specific features, details, components, and/or materials of a particular embodiment or implementation. In some instances, the benefit of simplicity may provide operational and economic benefits and exclusion of certain elements described herein is contemplated as within the scope of the invention herein by the inventors to achieve such benefits. In other instances, additional features and advantages may be recognized in certain embodiments and/or implementations that may not be present in all embodiments or implementations. Further, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the subject matter of the present disclosure. The features and advantages of the subject matter of the present disclosure will become more fully apparent from the following description and appended claims, or may be learned by the practice of the subject matter as set forth hereinafter.

[00067] The present subject matter may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.