Fuel pump assembly

Abstract

A fuel pump assembly includes a fuel pump. The fuel pump includes a camshaft having a cam lobe. The camshaft is configured to rotate. The fuel pump includes a first cam roller and a second cam roller disposed about an outer surface of the cam lobe, a first pumping assembly configured to interact with the first cam roller, and a second pumping assembly configured to interact with the second cam roller. The second pumping assembly is offset from the first pumping assembly. The fuel pump also includes a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly, and the second pumping assembly.

Description

[0001] This application is a divisional application of the application with the filing date of July 11, 2022, application number 202280047601.0, and invention title "Fuel Pump Assembly".

[0002] Cross - reference to related patent applications

[0003] This application claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 221,660, filed on July 14, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0004] The present disclosure relates to a fuel pump assembly for use under high fuel pressure conditions. Background

[0006] Fuel pumps are provided on internal combustion engines to deliver high - pressure fuel to fuel injectors, thereby enabling high - pressure injection events during engine operation. Depending on the operating parameters of the engine, the fuel pump can be configured to handle high fuel pressure and / or low fuel pressure. In cases where high - pressure fuel is required, high - pressure fuel lubrication pumps can be used. However, even though such fuel pumps are designed for high - pressure fuel, the forces exerted on various components can lead to component fatigue and wear as well as power loss. Overview

[0008] In one set of embodiments, a fuel pump assembly for an engine includes a fuel pump. The fuel pump includes a camshaft having a cam lobe. The camshaft is configured to rotate. The fuel pump includes a first cam roller and a second cam roller disposed around an outer surface of the cam lobe, a first pumping assembly configured to interact with the first cam roller, and a second pumping assembly configured to interact with the second cam roller. The second pumping assembly is offset from the first pumping assembly.

[0009] In an embodiment, the fuel pump assembly further includes a crankshaft configured to drive the fuel pump to draw fuel from a fuel tank to move the fuel towards a fuel injector, the crankshaft being operably coupled to the camshaft via a drive mechanism.

[0010] In an embodiment, the first pumping assembly includes a first plunger and a first plunger foot, the first plunger foot being in a facing relationship with the first cam roller such that the first plunger is configured to reciprocate in response to rotation of the cam lobe and the camshaft.

[0011] In an embodiment, the second pumping assembly includes a second plunger and a second plunger foot, and the second plunger foot is in a facing relationship with the second cam roller such that the second plunger is configured to reciprocate independently of the reciprocating movement of the first plunger in response to the rotation of the cam lobe and the camshaft.

[0012] In an embodiment, at least one of the first plunger foot and the second plunger foot is configured with a convex geometry; and at least one of the first cam roller and the second cam roller is configured with a concave geometry corresponding to the convex geometry of at least one of the first plunger foot and the second plunger foot.

[0013] In an embodiment, at least one of the first plunger foot and the second plunger foot is configured with a concave geometry; and at least one of the first cam roller and the second cam roller is configured with a convex geometry corresponding to the concave geometry of at least one of the first plunger foot and the second plunger foot.

[0014] In an embodiment, at least one of the first plunger foot and the second plunger foot is configured with a first flat geometry; and at least one of the first cam roller and the second cam roller is configured with a second flat geometry corresponding to the first flat geometry of at least one of the first plunger foot and the second plunger foot.

[0015] In an embodiment, the fuel pump assembly further includes a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly, and the second pumping assembly.

[0016] In an embodiment, the first cam roller and the second cam roller operate on the same cam lobe.

[0017] In an embodiment, the fuel pump assembly further includes a third pumping assembly and a third cam roller, and the third pumping assembly is configured to interact with the third cam roller.

[0018] In an embodiment, the fuel pump further includes a first control mechanism and a second control mechanism configured to control the relative position of the first cam roller with respect to the first plunger.

[0019] In an embodiment, the fuel pump further includes a third control mechanism configured to control the relative position of the second cam roller with respect to the second plunger together with the second control mechanism.

[0020] In an embodiment, the camshaft is eccentric such that the center of rotation of the cam lobe is offset relative to the axis of rotation of the camshaft.

[0021] In an embodiment, at least one of the first pumping assembly and the second pumping assembly is a unit barrel pumping assembly.

[0022] In an embodiment, the fuel pump assembly further includes at least one of a first tension member and a second tension member, the first tension member being configured to bias the first plunger toward the first cam roller, and the second tension member being configured to bias the second plunger toward the second cam roller.

[0023] In another set of embodiments, an engine system includes an engine block, a cylinder head coupled to the engine block, and a fuel system. The fuel system includes a plurality of fuel injectors located within the cylinder head and includes a fuel pump. The fuel pump includes a camshaft having cam lobes. The camshaft is configured to rotate. The fuel pump includes a first cam roller and a second cam roller disposed about an outer surface of the cam lobe, a first pumping assembly configured to interact with the first cam roller, and a second pumping assembly configured to interact with the second cam roller. The second pumping assembly is offset from the first pumping assembly.

[0024] In an embodiment, the engine system further includes a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly, and the second pumping assembly, the first pumping assembly and the second pumping assembly being located on opposite sides of a central cavity of the housing.

[0025] In an embodiment, the engine system further includes a bushing located between the cam lobe and at least one of the first cam roller and the second cam roller, the bushing facilitating movement of at least one of the first cam roller and the second cam roller relative to the cam lobe.

[0026] In an embodiment, the engine system further includes at least one of a first valve assembly and a second valve assembly, the first valve assembly being configured to regulate flow of low-pressure fluid into and out of a first pumping chamber, and the second valve assembly being configured to regulate flow of low-pressure fluid into and out of a second pumping chamber.

[0027] In an embodiment, the engine system further includes: a crankshaft configured to drive the fuel pump to draw fuel from a fuel tank to move the fuel toward the fuel injectors, the crankshaft being operably coupled to the camshaft via a drive mechanism; and an electric lift pump configured to draw the fuel from the fuel tank and supply the fuel to the fuel pump. Brief Description of the Drawings

[0029] The above and other features of the present invention and the manner of obtaining the same will become more apparent and the invention itself will be better understood from the following description of embodiments of the present invention taken in conjunction with the accompanying drawings, in which:

[0030] Figure 1 is a schematic view of an internal combustion engine configured for use with a fuel pump assembly of an exemplary embodiment;

[0031] Figure 2 is a perspective view of a fuel pump assembly of an exemplary embodiment;

[0032] Figure 3 is a schematic view of a fuel pump assembly of an exemplary embodiment;

[0033] Figure 4 is Figure 3 another schematic view of the fuel pump assembly of;

[0034] Figure 5 is Figure 3 a front view of the fuel pump assembly of; and

[0035] Figure 6 is a schematic view of a fuel pump assembly of an exemplary embodiment. Detailed Description

[0037] For purposes of facilitating an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the accompanying drawings and specific language will be used to describe these embodiments. However, it will be understood that no limitation of the scope of the present disclosure is thereby intended, and that any alterations and further modifications of the illustrated embodiments, as well as any further applications of the principles of the present disclosure as illustrated herein, which would ordinarily occur to one of ordinary skill in the art to which the present disclosure pertains, are contemplated herein.

[0038] Referring generally to the accompanying drawings, various embodiments disclosed herein relate to fuel lubricated fuel pumps configured for various fuel pressures, including high fuel pressures. The configurations of the fuel pumps disclosed herein provide a plunger interface design that is configured to improve the fatigue capability of the plunger at the plunger foot transition, reduce side loading forces at the plunger to reduce wear and scuffing power losses, and reduce sliding movement of the plunger foot at the interface with the cam ring or roller.

[0039] The figure shows an eccentric pump with two plungers and two cam rings operating on a single cam lobe. The pump assembly has an eccentric cam of a camshaft. The eccentric cam rotates together with the camshaft. There is a fluid film between the inner diameter of the cam ring and the outer diameter of the cam lobe, such that the cam ring has a rotational freedom with respect to the cam. The two plungers reciprocate in accordance with the rotation of the cam ring to pressurize the fuel entering and leaving the fuel pressurization chamber, the volume of which changes in response to the axial movement of the plungers. The two plungers, which are out of phase with each other, share the same cam lobe and are operated with separate cam rings. Due to the design of the plungers and each plunger operating with its own cam ring, the main contact mechanism at the junction between the cam ring and the plunger foot is rolling rather than sliding, which serves to improve the durability and performance of the pump, the peak operating pressure capacity and the packaging, while minimizing the cost. In addition, two separate cam rollers operating on a single lobe eliminate the need for two separate cam lobes that would otherwise space the distance between the two cam rollers. This further reduces the cost, the space required and the weight of the pump assembly.

[0040] Reference Figure 1 , a portion of an internal combustion engine 10 is shown as a simplified schematic diagram. The engine 10 includes an engine block 12 that supports the engine block 14, a cylinder head 16 coupled to the engine block 14, and a fuel system 20. The engine block 12 also includes a crankshaft 22, a plurality of pistons 24, and a plurality of connecting rods 26. The pistons 24 are configured to reciprocate within a plurality of engine cylinders 28, with one piston 24 positioned within each engine cylinder 28. Each piston 24 is operatively coupled to the crankshaft 22 by one of the connecting rods 26. A plurality of combustion chambers 32 are each defined by a combination of one piston 24, the cylinder head 16, and the engine cylinder 28. The movement of the pistons 24 under the action of the combustion process in the engine 10 causes the connecting rods 26 to move the crankshaft 22.

[0041] When the engine 10 is running, a combustion process occurs in the combustion chambers 32 to cause the movement of the pistons 24. The movement of the pistons 24 causes the movement of the connecting rods 26, which are drivingly connected to the crankshaft 22, and the movement of the connecting rods 26 causes the rotational movement of the crankshaft 22. The rotational angle of the crankshaft 22 can be measured by a control system to assist in timing combustion events in the engine 10 and for other purposes. The rotational angle of the crankshaft 22 can be measured at multiple locations, including the main crank pulley (not shown), the engine flywheel (not shown), the engine camshaft (not shown), or on the crankshaft 22.

[0042] The fuel system 20 includes a plurality of fuel injectors 30 located within the cylinder head 16. Each fuel injector 30 is fluidly coupled to a combustion chamber 32. In operation, the fuel system 20 supplies fuel to the fuel injectors 30, and then the fuel is injected into the combustion chamber 32 by the action of the fuel injectors 30. As described in further detail herein, the injection cycle can be defined as the interval that begins when the nozzle or needle element of the fuel injector 30 moves to allow fuel to flow from the fuel injector 30 into the associated combustion chamber 32, and ends when the nozzle or needle element moves to a position that blocks fuel from flowing from the fuel injector 30 into the combustion chamber 32.

[0043] In various embodiments, the crankshaft 22 can be operably coupled to the camshaft of at least one fuel pump via a drive mechanism (e.g., a gear train, a timing belt, a timing chain, etc.) (not shown). Thus, the crankshaft 22 can drive at least one fuel pump to draw fuel from the fuel tank in order to move the fuel toward the fuel injectors 30. In various embodiments, the fuel system 20 includes an electric lift pump to draw fuel from the fuel tank and supply the fuel to at least one fuel pump. A control system (not shown) provides control signals to the fuel injectors 30 that determine the operating parameters of each fuel injector 30, such as the length of time the fuel injector 30 operates and the number of fueling pulses per ignition or injection cycle period, thereby determining the amount of fuel delivered by each fuel injector 30.

[0044] Reference Figure 2, the fuel pump 40 can be a high-pressure, fuel-lubricated pump. The fuel pump 40 includes a housing 42 that is configured to support a plurality of components, such as drive members, and illustrates a camshaft 44 configured to rotate about a rotational axis 50 and at least one pumping assembly 46. The camshaft 44 can be coupled to a drive mechanism (e.g., gears, gear trains, etc.) (not shown). In various embodiments, at least one pumping assembly 46 is a unit barrel pumping assembly. In various embodiments, at least one pumping assembly 46 is integral with the housing 42. Illustratively, the pumping assembly 46 includes a first pumping assembly 46a located on a first side 48a of the housing 42 and a second pumping assembly 46b located on an opposite second side 48b of the housing 42. In various embodiments, the pumping assembly 46 can further include a third pumping assembly (not shown). The camshaft 44 is configured to extend through the housing 42. As shown, the camshaft 44 is supported within a central cavity 52 of the housing 42. The first pumping assembly 46a and the second pumping assembly 46b are located on opposite sides of the central cavity 52 in a direction perpendicular to the rotational axis 50 of the camshaft. For example, in various embodiments, the first pumping assembly 46a and the second pumping assembly 46b are positioned approximately 180 degrees from each other relative to the rotational axis 50. In various embodiments, the first pumping assembly 46a and the second pumping assembly 46b can be positioned in other configurations determined by the space limitations of the fuel pump 40.

[0045] Now refer to Figures 3 - 6 , the housing 42 also supports a first cam roller 54 (e.g., cam ring) configured to engage a cam lobe 56 of the camshaft 44. The first pumping assembly 46a includes a first plunger 70, a first tension member 68 (e.g., spring), and a first valve assembly 72 configured to regulate the flow of low-pressure fluid into and out of a first pumping chamber 74. The first pumping chamber 74 is defined by a portion of the first plunger 70 and a portion of the first pumping assembly 46a, as further disclosed herein. The first plunger 70 is also fluidly coupled to a first plunger outlet valve 73 of the first pumping assembly 46a.

[0046] The first plunger 70 includes a first plunger foot 76. The first plunger foot 76 is configured to contact and travel along the first cam roller 54 (e.g., be in a facing relationship with the first cam roller 54) during operation of the fuel pump 40. More specifically, during operation of the fuel pump 40, the camshaft 44 rotates, causing the cam lobe 56 to rotate. The camshaft 44 is an eccentric camshaft, where the center of rotation of the cam lobe 56 is offset relative to the axis of rotation 50 of the camshaft 44. The first cam roller 54 surrounds the cam lobe 56 and is configured to rotate around the cam lobe 56. A bushing 58 operated by a hydraulic film or fluid is located at the junction between the inner perimeter of the first cam roller 54 and the outer perimeter of the cam lobe 56 to facilitate movement of the first cam roller 54 relative to the cam lobe 56. The first plunger 70 is biased toward the first cam roller 54 by the first tension member 68 such that the first plunger foot 76 remains in contact with the first cam roller 54 during rotation of the first cam roller 54. Contact between the first plunger foot 76 and the first cam roller 54 causes the first plunger 70 to reciprocate along the wall as rotation of the cam lobe 56 moves the first plunger 70 along the first reciprocation axis 82. The first reciprocation axis 82 is concentric with the centerline of the first plunger 70.

[0047] When the first plunger 70 reciprocates along the first reciprocation axis 82 (causing the first plunger 70 to move), the first plunger foot 76 moves toward and away from the axis of rotation 50 of the camshaft 44, thereby adjusting the volume of the first pumping chamber 74. More specifically, when the cam lobe 56 rotates to a position toward the first pumping assembly 46a, the first plunger 70 also moves toward the first pumping assembly 46a and is at the top-dead-center position, thereby minimizing the volume of the first pumping chamber 74.

[0048] When the camshaft 44 continues to rotate around the axis of rotation 50 and the cam lobe 56 rotates toward the second pumping assembly 46b, the first plunger 70 reciprocates along the first reciprocation axis 82 and moves toward the axis of rotation 50. Due to the first tension member 68, the first plunger 70 is biased toward the first cam roller 54, and the first plunger 70 moves toward the axis of rotation 50, thereby increasing the volume of the first pumping chamber 74. When the volume of the first pumping chamber 74 is at its maximum, the first plunger 70 is at the bottom-dead-center position, and the maximum amount of fluid from the first pumping assembly 46a flows into the first pumping chamber 74.

[0049] Still referring to Figures 3 - 4, the housing 42 also supports a second cam roller 55 (e.g., a cam ring) that is configured to engage a cam lobe 56 of the camshaft 44. In various embodiments, the housing 42 may also support a third cam roller (not shown), and a third pumping assembly is configured to interact with the third cam roller. The second pumping assembly 46b includes a second plunger 71, a second tension member 69 (e.g., a spring), and a second valve assembly 75 that is configured to regulate the flow of low-pressure fluid into and out of the second pumping chamber 77. The second pumping chamber 77 is defined by a portion of the second plunger 71 and a portion of the second pumping assembly 46b. The second plunger 71 is also fluidly coupled to a second plunger outlet valve 79 of the second pumping assembly 46b.

[0050] The second plunger 71 includes a second plunger foot 81. The second plunger foot 81 is configured to contact the second cam roller 55 and travel along the second cam roller 55 (e.g., be in a facing relationship with the second cam roller 55) during operation of the fuel pump 40. More specifically, during operation of the fuel pump 40, the camshaft 44 rotates, causing the cam lobe 56 to rotate. The camshaft 44 is an eccentric camshaft, where the center of rotation of the cam lobe 56 is offset relative to the axis of rotation 50 of the camshaft 44. The second cam roller 55 surrounds the cam lobe 56 and is configured to rotate about the cam lobe 56. A bushing 58 operated by a hydraulic film or fluid is located at the junction between the inner perimeter of the second cam roller 55 and the outer perimeter of the cam lobe 56 to facilitate movement of the second cam roller 55 relative to the cam lobe 56. The second plunger 71 is biased toward the second cam roller 55 by the second tension member 69 such that the second plunger foot 81 remains in contact with the second cam roller 55 during rotation of the second cam roller 55. Contact of the second plunger foot 81 with the second cam roller 55 causes the second plunger 71 to reciprocate along the wall as rotation of the cam lobe 56 moves the second plunger 71 along a second reciprocation axis 83. The second reciprocation axis 83 is concentric with the centerline of the second plunger 71.

[0051] As the second plunger 71 reciprocates along the second reciprocation axis 83 (causing the second plunger 71 to move), the second plunger foot 81 moves toward and away from the axis of rotation 50 of the camshaft 44, thereby adjusting the volume of the second pumping chamber 77. More specifically, when the cam lobe 56 rotates toward the second pumping assembly 46b to a position, the second plunger 71 also moves toward the second pumping assembly 46b and is at a top dead center position, thereby minimizing the volume of the second pumping chamber 77.

[0052] As the camshaft 44 continues to rotate about the axis of rotation 50 and the cam lobe 56 rotates towards the first pumping assembly 46a, the second plunger 71 reciprocates along the second reciprocation axis 83 and moves towards the axis of rotation 50. Due to the second tension member 69, the second plunger 71 is biased towards the second cam roller 55, and the second plunger 71 moves towards the axis of rotation 50, thereby increasing the volume of the second pumping chamber 77. When the volume of the second pumping chamber 77 is at its maximum, the second plunger 71 is at the bottom dead center position, and the maximum amount of fluid from the second pumping assembly 46b flows in the second pumping chamber 77.

[0053] The first plunger foot 76 and the second plunger foot 81 may have different configurations. For example, in Figure 3 and Figure 4 the illustrated embodiment, each of the first plunger foot 76 and the second plunger foot 81 has a generally convex configuration. More specifically, the contact surface of each of the first cam roller 54 and the second cam roller 55 has a generally concave configuration corresponding to the convex geometric configuration of at least one of the first plunger foot 76 and the second plunger foot 81. In various configurations, at least one of the first plunger foot 76 and the second plunger foot 81 may be concave, while the contact surface of at least one of the first cam roller 54 and the second cam roller 55 is convex, corresponding to the concave geometric configuration of at least one of the first plunger foot 76 and the second plunger foot 81. Due to the curved geometric configuration of the first plunger foot 76 and the first cam roller 54, the load distribution at the first cam roller 54 and the first plunger foot 76 is increased. By increasing the load distribution at the contact surface, the bending stress on the first plunger foot 76 is reduced.

[0054] In addition, the first cam roller 54 and the first plunger foot 76, and the second cam roller 55 and the second plunger foot 81 may have other different configurations. For example, the first cam roller 54, the first plunger foot 76, the second cam roller 55, and the second plunger foot 81 may have a generally flat or linear configuration. The first flat geometric configuration of at least one of the first plunger foot 76 and the second plunger foot 81 corresponds respectively to the second flat geometric configuration of at least one of the first cam roller 54 and the second cam roller 55. For example, the first cam roller 54, the first plunger foot 76, the second cam roller 55, and the second plunger foot 81 may have a generally flat or linear configuration near the center of the contact area between the first plunger foot 76 and the first cam roller 54 and the contact area between the second plunger foot 81 and the second cam roller 55, and then have surfaces near the outer boundary of the contact area, where the local axial separation distance between the surfaces of the first plunger foot 76 and the first cam roller 54 and between the surfaces of the second plunger foot 81 and the second cam roller 55 is increased to reduce the magnitude of the edge load between the contact surfaces.

[0055] Now referring to Figure 6 , in various embodiments, the fuel pump 40 may further include a first control mechanism 84 and a second control mechanism 85, and the first control mechanism 84 and the second control mechanism 85 are configured to control the relative position of the first cam roller 54 relative to the first plunger 70 (e.g., the first reciprocating motion axis 82). For example, the first cam roller 54 and the first plunger foot 76 may be configured to cooperate with the first control mechanism 84 and the second control mechanism 85 provided on the cam lobe 56. In various embodiments, the first control mechanism 84 and the second control mechanism 85 may be provided on the housing 42. More specifically, the first control mechanism 84 and the second control mechanism 85 may control the relative position of the first cam roller 54 relative to the first plunger 70 and, if necessary, carry a thrust load. The second cam roller 55 and the second plunger foot 81 may be configured to cooperate with the second control mechanism 85 and the third control mechanism 86 provided on the cam lobe 56. In various embodiments, the second control mechanism 85 and the third control mechanism 86 may be provided on the housing 42. More specifically, the second control mechanism 85 and the third control mechanism 86 may control the relative position of the second cam roller 55 relative to the second plunger 71 and, if necessary, carry a thrust load.

[0056] During typical operation of the fuel pump 40, since the first plunger 70 and the second plunger 71 operate in combination with their respective cam rings (i.e., the first cam roller 54 and the second cam roller 55, respectively), there is a first rolling motion between the first plunger foot 76 and the first cam roller 54, and a second rolling motion (independent of the first rolling motion) between the second plunger foot 81 and the second cam roller 55.

[0057] Conversely, if the first plunger 70 and the second plunger 71 share the same cam ring / roller, the first plunger 70 and the second plunger 71 transmit forces acting on the cam ring in opposite rotational directions. The opposite force directions cause at least one of the first plunger 70 and the second plunger 71 to have a sliding motion (e.g., a sliding motion between the plunger foot and its corresponding cam roller due to an imbalance of forces applied by a full rotation of the cam lobe). This sliding generates heat, reduces efficiency, causes wear, etc. Therefore, operating the first plunger 70 and the second plunger 71 each on its own unique cam ring (i.e., the first cam roller 54 and the second cam roller 55, respectively) results in a relative engagement motion that is mainly rolling. The relative offset of the positions of the plungers and their corresponding elements along the rotational axis 50 enables the first plunger 70 and the second plunger 71 to independently control the axial position of each of the first cam roller 54 and the second cam roller 55, respectively. By further rotationally offsetting the first plunger 70 and the second plunger 71, the two pumping events are sufficiently out of phase with each other to minimize the maximum positive torque and the maximum negative torque on the camshaft 44.

[0058] As shown and explained herein, the fuel pump 40 includes two pumping members, a first pumping assembly 46a and a second pumping assembly 46b, each pumping member respectively including a first plunger 70 and a second plunger 71 and a first cam roller 54 and a second cam roller 55. Thus, the first cam roller 54 rotates or orbits around the outer surface of the cam lobe 56, and when the second cam roller 55 simultaneously rotates or orbits around the outer surface of the cam lobe 56, the reciprocating motion of the first plunger 70 allows the contact surface at the engagement portion of the first plunger foot 76 and the first cam roller 54 to rotate without the reaction force of the second plunger 71, and vice versa. Positioning the first cam roller 54 and the second cam roller 55 on the same cam lobe 56 is conducive to reducing the bending stress on the camshaft 44 because the first cam roller 54 and the second cam roller 55 are close to each other. In addition, by reducing the sliding effect between the plunger foot and the cam roller, a reduction in friction and heat is observed, which results in increased efficiency and extended life of the system.

[0059] Although this specification contains many specific implementation details, these should not be construed as limitations on the scope of what is claimed, but rather as descriptions of features specific to particular implementations. Certain features described in the context of separate implementations in this specification can also be implemented combinatorially in a single implementation. Conversely, the various features described in the context of a single implementation can also be implemented separately or in any suitable sub-combination in multiple implementations. Moreover, although features may be described as acting in certain combinations and even initially claimed as such, one or more features from the claimed combination can in some cases be deleted from the combination, and the claimed combination can relate to a sub-combination or a variation of a sub-combination.

[0060] As used herein, the terms "substantially" and similar terms are intended to have a broad meaning consistent with the common and accepted usage of those of ordinary skill in the art to which the subject matter of this disclosure pertains. Those skilled in the art who review this disclosure should understand that these terms are intended to permit the description of certain features being described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that non-substantive or immaterial modifications or variations of the subject matter being described and claimed are considered to be within the scope of this disclosure as set forth in the appended claims.

[0061] As used herein, the term "coupled" and like terms mean that two components are directly or indirectly connected to each other. Such connection can be fixed (e.g., permanent) or movable (e.g., removable or releasable). Such connection can be achieved by integrally forming two components or two components and any additional intermediate components into a single unitary body, or by attaching two components or two components and any additional intermediate components to each other.

[0062] It is important to note that the structures and arrangements of the various systems shown in the respective exemplary embodiments are illustrative rather than restrictive in nature. All changes and modifications within the spirit and / or scope of the described embodiments are to be protected. It should be understood that some features may not be necessary, and embodiments lacking various features may be considered within the scope of the present disclosure, which is defined by the appended claims. When the language "a portion" is used, the item can include a portion and / or the whole item, unless expressly stated to the contrary.

[0063] In addition, the term "or" is used in the inclusive sense (rather than the exclusive sense) in the context of a series of elements, such that when used to associate a series of elements, the term "or" means one, some, or all of the elements in the series. Unless otherwise expressly stated, conjunctive language such as the phrase "at least one of X, Y, and Z" is understood in context to generally mean that items, terms, etc. can be X, Y, Z, X and Y, X and Z, Y and Z, or X, Y, and Z (i.e., any combination of X, Y, and Z). Thus, unless otherwise indicated, such conjunctive language generally does not intend to imply that certain embodiments require the presence of at least one of each of X, at least one of Y, and at least one of Z.

Claims

1. A fuel pump assembly for an engine, comprising: a fuel pump, the fuel pump comprising: - a camshaft having cam lobes, the camshaft being configured to rotate; - a first cam roller and a second cam roller disposed around an outer surface of the cam lobe; - a first pumping assembly configured to interact with the first cam roller, the first pumping assembly including a first plunger and a first plunger foot, the first plunger foot being in a facing relationship with the first cam roller such that the first plunger is configured to reciprocate in response to rotation of the cam lobe and the camshaft; and - a second pumping assembly configured to interact with the second cam roller, wherein the second pumping assembly is offset from the first pumping assembly, - wherein one of the first plunger foot and the first cam roller is configured with a convex geometry and the other of the first plunger foot and the first cam roller is configured with a concave geometry corresponding to the convex geometry of the one of the first plunger foot and the first cam roller.

2. The fuel pump assembly according to claim 1, further comprising a crankshaft configured to drive the fuel pump to draw fuel from a fuel tank to move the fuel towards a fuel injector, the crankshaft being operably coupled to the camshaft via a drive mechanism.

3. The fuel pump assembly according to claim 1, wherein, the second pumping assembly includes a second plunger and a second plunger foot, the second plunger foot being in a facing relationship with the second cam roller such that the second plunger is configured to reciprocate independently of the reciprocating movement of the first plunger in response to rotation of the cam lobe and the camshaft.

4. The fuel pump assembly according to claim 3, wherein, one of the second plunger foot and the second cam roller is configured with a convex geometry and the other of the second plunger foot and the second cam roller is configured with a concave geometry corresponding to the convex geometry of the one of the second plunger foot and the second cam roller.

5. The fuel pump assembly according to claim 3, wherein: the second plunger foot is configured with a first flat geometry; and the second cam roller is configured with a second flat geometry corresponding to the first flat geometry of the second plunger foot.

6. The fuel pump assembly according to claim 1, further comprising a first valve assembly configured to regulate the flow of low-pressure fluid into and out of a first pumping chamber defined by a portion of the first plunger and a portion of the first pumping assembly.

7. The fuel pump assembly according to any one of claims 1-6, further comprising a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly, and the second pumping assembly.

8. The fuel pump assembly according to any one of claims 1-6, wherein, The first cam roller and the second cam roller operate on the same cam lobe.

9. The fuel pump assembly according to any one of claims 1-6 further includes a third pumping assembly and a third cam roller, the third pumping assembly being configured to interact with the third cam roller.

10. The fuel pump assembly according to any one of claims 1-6, wherein, the fuel pump further includes a first control mechanism and a second control mechanism, the first control mechanism and the second control mechanism being configured to control the relative position of the first cam roller relative to the first plunger.

11. A fuel pump assembly for an engine, comprising: a fuel pump, the fuel pump including: - a camshaft having cam lobes, the camshaft being configured to rotate; - a first cam roller and a second cam roller disposed around an outer surface of the cam lobe; - a first pumping assembly configured to interact with the first cam roller, the first pumping assembly including a first plunger and a first plunger foot, the first plunger foot being in a facing relationship with the first cam roller such that the first plunger is configured to reciprocate in response to rotation of the cam lobe and the camshaft; and - a second pumping assembly configured to interact with the second cam roller, wherein the second pumping assembly is offset from the first pumping assembly, the second pumping assembly including a second plunger and a second plunger foot, the second plunger foot being in a facing relationship with the second cam roller such that the second plunger is configured to reciprocate in response to rotation of the cam lobe and the camshaft, wherein: -- at least one of the first plunger foot and the second plunger foot is configured with a first flat geometry; and -- at least one of the first cam roller and the second cam roller is configured with a second flat geometry corresponding to the first flat geometry of at least one of the first plunger foot and the second plunger foot.

12. The fuel pump assembly according to claim 11, wherein, the camshaft is eccentric such that a center of rotation of the cam lobe is offset relative to an axis of rotation of the camshaft.

13. The fuel pump assembly according to claim 11, wherein, at least one of the first pumping assembly and the second pumping assembly is a unit barrel pumping assembly.

14. The fuel pump assembly according to any one of claims 11-13 further includes a tension member configured to bias the first plunger toward the first cam roller.

15. The fuel pump assembly according to any one of claims 11-13 further includes a bushing located between the cam lobe and the first cam roller, the bushing facilitating movement of the first cam roller relative to the cam lobe.

16. A fuel pump assembly for an engine, comprising: a fuel pump, the fuel pump including: - a camshaft having cam lobes, the camshaft being configured to rotate; - A first cam roller and a second cam roller, the first cam roller and the second cam roller being disposed around an outer surface of the cam lobe; - A first pumping assembly configured to interact with the first cam roller, the first pumping assembly including a first plunger and a first plunger foot, the first plunger foot being in a facing relationship with the first cam roller such that the first plunger is configured to reciprocate in response to rotation of the cam lobe and the camshaft; - A second pumping assembly configured to interact with the second cam roller, the second pumping assembly including a second plunger and a second plunger foot, the second plunger foot being in a facing relationship with the second cam roller such that the second plunger is configured to reciprocate in response to rotation of the cam lobe and the camshaft; - A first control mechanism and a second control mechanism configured to control a relative position of the first cam roller with respect to the first plunger; and - A third control mechanism configured to control, together with the second control mechanism, a relative position of the second cam roller with respect to the second plunger.

17. The fuel pump assembly according to claim 16, wherein, the fuel pump further includes a housing, and wherein the first control mechanism and the second control mechanism are located on the housing.

18. The fuel pump assembly according to claim 16, wherein, the third control mechanism is located on the cam lobe.

19. The fuel pump assembly according to claim 16, wherein, the fuel pump further includes a housing, and wherein the second control mechanism and the third control mechanism are located on the housing.

20. The fuel pump assembly according to any one of claims 16-19, wherein, the second pumping assembly is offset from the first pumping assembly.

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