Fuel pump components

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 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. 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] Cross-references to related patent applications

[0002] This application claims priority to and the 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

[0003] The present disclosure relates to a fuel pump assembly for use under high fuel pressure conditions.

[0004] background

[0005] A fuel pump is provided on an internal combustion engine to deliver high pressure fuel to the fuel injectors to achieve a high pressure injection event when the engine is running. Depending on the operating parameters of the engine, the fuel pump may be configured to handle high fuel pressures and / or low fuel pressures. In situations where high pressure fuel is required, a high pressure fuel lubrication pump may be used. However, even if such a fuel pump is designed for high pressure fuel, the forces exerted on the various components may result in fatigue and wear of the components and loss of power.

[0006] Overview

[0007] 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.

[0008] 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 toward the fuel injector, the crankshaft being operably coupled to the camshaft via a drive mechanism.

[0009] In an embodiment, the first pumping assembly includes a first plunger and a first plunger foot in confronting 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.

[0010] In an embodiment, the second pumping assembly includes a second plunger and a second plunger foot, wherein the second plunger foot is in confronting relationship with the second cam roller so that the second plunger is configured to reciprocate in response to rotation of the cam lobe and the camshaft independently of reciprocating movement of the first plunger.

[0011] In an embodiment, at least one of the first plunger foot and the second plunger foot is constructed with a convex geometric structure; and at least one of the first cam roller and the second cam roller is constructed with a concave geometric structure corresponding to the convex geometric structure of the at least one of the first plunger foot and the second plunger foot, respectively.

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

[0013] In an embodiment, at least one of the first plunger foot and the second plunger foot is constructed with a first flat geometric structure; and at least one of the first cam roller and the second cam roller is constructed with a second flat geometric structure corresponding to the first flat geometric structure of the at least one of the first plunger foot and the second plunger foot, respectively.

[0014] 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.

[0015] In an embodiment, the first cam roller and the second cam roller operate on the same cam lobe.

[0016] In an embodiment, the fuel pump assembly further includes a third pumping assembly and a third cam roller, the third pumping assembly being configured to interact with the third cam roller.

[0017] In an embodiment, the fuel pump further includes a first control mechanism and a second control mechanism, wherein the first control mechanism and the second control mechanism are configured to control a relative position of the first cam roller with respect to the first plunger.

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

[0019] In an embodiment, the camshaft is eccentric such that the centre of rotation of the cam lobe is offset relative to the axis of rotation of the camshaft.

[0020] In an embodiment, at least one of the first pumping assembly and the second pumping assembly is a unit barrel pumping assembly.

[0021] In an embodiment, the fuel pump assembly further includes at least one of a first tension member configured to bias the first plunger toward the first cam roller and a second tension member configured to bias the second plunger toward the second cam roller.

[0022] 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 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.

[0023] In an embodiment, the engine system further comprises a housing configured to support the camshaft, the first cam roller, the second cam roller, the first pumping assembly and the second pumping assembly, wherein the first pumping assembly and the second pumping assembly are located on opposite sides of a central cavity of the housing.

[0024] 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.

[0025] In an embodiment, the engine system further comprises at least one of a first valve assembly configured to regulate flow of the low pressure fluid into and out of the first pumping chamber and a second valve assembly configured to regulate flow of the low pressure fluid into and out of the second pumping chamber.

[0026] In an embodiment, the engine system further comprises: a crankshaft configured to drive the fuel pump to draw fuel from a fuel tank to move the fuel toward a fuel injector, the crankshaft being operably connected 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

[0028] The above and other features of the invention and the manner in which these features are obtained will become more apparent and the invention itself will be better understood by referring to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1is a schematic diagram of an internal combustion engine configured for use with an example embodiment fuel pump assembly;

[0030] Figure 2 is a perspective view of a fuel pump assembly of an example embodiment;

[0031] Figure 3 is a schematic diagram of a fuel pump assembly of an example embodiment;

[0032] Figure 4 yes Figure 3 Another schematic diagram of a fuel pump assembly;

[0033] Figure 5 yes Figure 3 A front view of a fuel pump assembly; and

[0034] Figure 6 is a schematic diagram of a fuel pump assembly of an example embodiment.

[0035] Detailed Description

[0036] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe these embodiments. It will be understood, however, that no limitation of the scope of the present disclosure is thereby intended, and any changes and further modifications in the illustrated embodiments that would normally occur to one skilled in the art to which the present disclosure relates, as well as any further applications of the principles of the present disclosure as illustrated in the present disclosure, are contemplated herein.

[0037] Referring generally to the drawings, various embodiments disclosed herein relate to fuel lubricated fuel pumps configured for various fuel pressures, including high fuel pressures. The configuration of the fuel pump disclosed herein provides a plunger interface design for improving fatigue capability of the plunger at the plunger foot transition, reducing side loading forces at the plunger to reduce wear and scraping power losses, and reducing sliding motion of the plunger foot at the interface with the cam ring or roller.

[0038] 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 with the camshaft. There is a fluid film between the inner diameter of the cam ring and the outer diameter of the cam lobe, so that the cam ring has rotational freedom relative to the cam. The two plungers reciprocate according to the rotation of the cam ring to pressurize the fuel entering and leaving the fuel pressurization chamber, and the volume of the fuel pressurization chamber changes in response to the axial movement of the plunger. Two plungers that are out of phase with each other share the same cam lobe and operate 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 joint between the cam ring and the plunger foot is rolling rather than sliding, which is used to improve the durability and performance of the pump, the peak operating pressure capability and packaging, while minimizing the cost. In addition, the two separate cam rollers operating on a single lobe eliminate the need for two separate cam lobes, which would otherwise separate the distance between the two cam rollers. This further reduces the cost, required space and weight of the pump assembly.

[0039] refer to Figure 1 , a portion of an internal combustion engine 10 is shown as a simplified schematic diagram. The engine 10 includes an engine body 12 supporting an engine block 14, a cylinder head 16 coupled to the engine block 14, and a fuel system 20. The engine body 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, wherein one piston 24 is positioned in each engine cylinder 28. Each piston 24 is operably coupled to the crankshaft 22 by one of the connecting rods 26. A plurality of combustion chambers 32 are each defined by the 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.

[0040] When engine 10 is running, a combustion process occurs in combustion chamber 32 to cause movement of piston 24. Movement of piston 24 causes movement of connecting rod 26, which is drivingly connected to crankshaft 22, and movement of connecting rod 26 causes rotational motion of crankshaft 22. The rotational angle of crankshaft 22 may be measured by the control system to help time combustion events in engine 10 and for other purposes. The rotational angle of crankshaft 22 may be measured at a variety of locations, including a primary crank pulley (not shown), an engine flywheel (not shown), an engine camshaft (not shown), or on crankshaft 22.

[0041] 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 one combustion chamber 32. In operation, the fuel system 20 provides fuel to the fuel injectors 30, which are then injected into the combustion chambers 32 by the action of the fuel injectors 30. As further detailed herein, an injection cycle can be defined as an interval beginning when a nozzle or needle member of a fuel injector 30 moves to allow fuel to flow from the fuel injector 30 into the associated combustion chamber 32, and ending when the nozzle or needle member moves to a position that blocks fuel from flowing from the fuel injector 30 into the combustion chamber 32.

[0042] In various embodiments, the crankshaft 22 can be operably coupled to a 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 the at least one fuel pump to draw fuel from the fuel tank so as 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 the at least one fuel pump. A control system (not shown) provides control signals to the fuel injectors 30 that determine 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, thereby determining the amount of fuel delivered by each fuel injector 30.

[0043] refer to 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 multiple components (such as a drive member), and a camshaft 44 configured to rotate around a rotation axis 50 and at least one pumping assembly 46 are illustrated. The camshaft 44 can be coupled to a drive mechanism (e.g., a gear, a gear train, 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 may also 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 may be positioned in other configurations that may be dictated by the space constraints of the fuel pump 40.

[0044] Reference now Figure 3-Figure 6 , the housing 42 also supports a first cam roller 54 (e.g., a 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., a 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.

[0045] The first plunger 70 includes a first plunger foot 76. The first plunger foot 76 is configured to contact the first cam roller 54 and travel along the first cam roller 54 (e.g., 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, thereby rotating the cam lobe 56. The camshaft 44 is an eccentric camshaft in which the rotation center of the cam lobe 56 is offset relative to the rotation axis 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 with a hydraulic film or fluid is located at a joint between the inner periphery of the first cam roller 54 and the outer periphery 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 due to the first tension member 68, so that the first plunger foot 76 remains in contact with the first cam roller 54 during rotation of the first cam roller 54. Contact of the first plunger foot 76 with 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 a first reciprocation axis 82. The first reciprocation axis 82 is concentric with the centerline of the first plunger 70.

[0046] As the first plunger 70 reciprocates along the first reciprocating axis 82 (causing the first plunger 70 to move), the first plunger foot 76 moves toward and away from the rotation axis 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 in a top-dead-center position, thereby minimizing the volume of the first pumping chamber 74.

[0047] As the camshaft 44 continues to rotate about the rotation axis 50 and the cam lobe 56 rotates toward the second pumping assembly 46b, the first plunger 70 reciprocates along the first reciprocating axis 82 and moves toward the rotation axis 50. The first plunger 70 is biased toward the first cam roller 54 due to the first tension member 68, and the first plunger 70 moves toward the rotation axis 50, thereby increasing the volume of the first pumping chamber 74. When the volume of the first pumping chamber 74 is maximum, the first plunger 70 is in a bottom-dead-center position, and a maximum amount of fluid from the first pumping assembly 46a flows in the first pumping chamber 74.

[0048] Still refer to Figure 3-Figure 4, the housing 42 also supports a second cam roller 55 (e.g., a cam ring) that is configured to engage with a cam lobe 56 of the camshaft 44. In various embodiments, the housing 42 may also support a third cam roller (not shown), and the 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 a 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.

[0049] 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., 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, thereby rotating the cam lobe 56. The camshaft 44 is an eccentric camshaft in which the rotation center of the cam lobe 56 is offset relative to the rotation axis 50 of the camshaft 44. The second cam roller 55 surrounds the cam lobe 56 and is configured to rotate around the cam lobe 56. A bushing 58 operated with a hydraulic film or fluid is located at a joint between the inner periphery of the second cam roller 55 and the outer periphery 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 due to the second tension member 69, so that the second plunger foot 81 remains in contact with the second cam roller 55 during rotation of the second cam roller 55. The contact of the second plunger foot 81 with the second cam roller 55 causes the second plunger 71 to reciprocate along the wall as the rotation of the cam lobe 56 moves the second plunger 71 along the second reciprocation axis 83. The second reciprocation axis 83 is concentric with the centerline of the second plunger 71.

[0050] When the second plunger 71 reciprocates along the second reciprocating axis 83 (causing the second plunger 71 to move), the second plunger foot 81 moves toward and away from the rotation axis 50 of the camshaft 44, thereby adjusting the volume of the second pumping chamber 77. More specifically, when the cam lobe 56 rotates to a position toward the second pumping assembly 46b, the second plunger 71 also moves toward the second pumping assembly 46b and is at the top dead center position, thereby minimizing the volume of the second pumping chamber 77.

[0051] As the camshaft 44 continues to rotate about the rotation axis 50 and the cam lobe 56 rotates toward the first pumping assembly 46a, the second plunger 71 reciprocates along the second reciprocating axis 83 and moves toward the rotation axis 50. Due to the second tension member 69, the second plunger 71 is biased toward the second cam roller 55, and the second plunger 71 moves toward the rotation axis 50, thereby increasing the volume of the second pumping chamber 77. When the volume of the second pumping chamber 77 is maximum, the second plunger 71 is in the bottom dead center position, and the maximum amount of fluid from the second pumping assembly 46b flows in the second pumping chamber 77.

[0052] The first plunger foot 76 and the second plunger foot 81 may have different configurations. Figure 3 and Figure 4 In 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, respectively. 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, respectively. 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.

[0053] 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 can 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 can have a substantially 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 to the second flat geometric configuration of at least one of the first cam roller 54 and the second cam roller 55, respectively. For example, the first cam roller 54, the first plunger foot 76, the second cam roller 55 and the second plunger foot 81 can have a substantially 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 a surface near the outer boundary of the contact area, wherein the local axial separation distance between the surface of the first plunger foot 76 and the first cam roller 54 and between the surface of the second plunger foot 81 and the second cam roller 55 increases to reduce the edge load magnitude between the contact surfaces.

[0054] Reference now Figure 6 In various embodiments, the fuel pump 40 may further include a first control mechanism 84 and a second control mechanism 85, which are configured to control the relative position of the first cam roller 54 relative to the first plunger 70 (e.g., the first reciprocating 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 disposed on the cam lobe 56. In various embodiments, the first control mechanism 84 and the second control mechanism 85 may be disposed 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 thrust loads. 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 disposed on the cam lobe 56. In various embodiments, the second control mechanism 85 and the third control mechanism 86 may be disposed 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 with respect to the second plunger 71 and, if necessary, carry a thrust load.

[0055] During typical operation of the fuel pump 40, because the first plunger 70 and the second plunger 71 operate in conjunction with their unique 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 there is a second rolling motion (independent of the first rolling motion) between the second plunger foot 81 and the second cam roller 55.

[0056] In contrast, 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 result in sliding motion of at least one of the first plunger 70 and the second plunger 71 (e.g., sliding motion between the plunger foot and its corresponding cam roller due to the imbalance of forces applied through a full rotation of the cam lobe). This sliding motion generates heat, reduces efficiency, causes wear, etc. Therefore, the first plunger 70 and the second plunger 71 are each operated on their own unique cam ring (i.e., the first cam roller 54 and the second cam roller 55, respectively), resulting in a relative engagement motion that is primarily rolling. The relative offset in position between 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 and second plungers 70 and 71 , the two pumping events are sufficiently out of phase with each other to minimize the maximum positive and negative torques on the camshaft 44 .

[0057] 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 including a first plunger 70 and a second plunger 71 and a first cam roller 54 and a second cam roller 55, respectively. In this way, the first cam roller 54 rotates or revolves around the outer surface of the cam lobe 56, and when the second cam roller 55 simultaneously rotates or revolves around the outer surface of the cam lobe 56, the reciprocating motion of the first plunger 70 allows the contact surface at the junction 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 leads to improved efficiency and extended life of the system.

[0058] Although this specification contains many specific implementation details, these should not be interpreted as limitations on the scope of the claimed content, but should be interpreted as descriptions of features peculiar to specific implementations. Certain features described in the context of separate implementations in this specification may also be implemented in combination in a single implementation. On the contrary, the various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations. In addition, although features may be described as working in certain combinations and even initially claimed as such, one or more features from the claimed combination may be deleted from the combination in some cases, and the claimed combination may involve a sub-combination or a deformation of a sub-combination.

[0059] As utilized herein, the term "substantially" and similar terms are intended to have a broad meaning consistent with common and accepted usage by those of ordinary skill in the art to which the subject matter of the present disclosure belongs. Those skilled in the art who review the present disclosure should understand that these terms are intended to allow description of certain features described and claimed without limiting the scope of these features to the precise numerical ranges provided. Therefore, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the present disclosure as described in the appended claims.

[0060] As used herein, the term "coupled" and similar terms mean the joining of two components directly or indirectly to one another. Such joining may be fixed (e.g., permanent) or movable (e.g., removable or releasable). Such joining may be achieved by the two components, or the two components and any additional intermediate components, being integrally formed as a single unitary body with one another, or by the two components, or the two components and any additional intermediate components, being attached to one another.

[0061] It is important to note that the structure and arrangement of the various systems shown in the various example embodiments are illustrative and non-restrictive in nature. All changes and modifications within the spirit and / or scope of the described embodiments need to be protected. It should be understood that some features may not be necessary, and embodiments lacking various features may be considered to be within the scope of the present disclosure, which is defined by the appended claims. When the language "a portion" is used, the item may include a portion and / or the entire item unless explicitly stated to the contrary.

[0062] In addition, the term "or" is used in its inclusive sense (rather than its exclusive meaning) in the context of a series of elements, such that when used to relate a series of elements, the term "or" means one, some, or all of the elements in the series. Unless otherwise explicitly stated, conjunction language such as the phrase "at least one of X, Y, and Z" is understood in the context to be generally used to express that an item, term, 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). Therefore, unless otherwise specified, such conjunction language is generally not intended to imply that certain embodiments require that at least one X, at least one Y, and at least one Z each be present.

Claims

1. A fuel pump assembly for an engine, comprising: A fuel pump, the fuel pump comprising: a camshaft having a cam lobe, 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 about an outer surface of the cam lobe, wherein the first cam roller and the second cam roller operate on the same cam lobe; a first pumping assembly configured to interact with the first cam roller; and A second pumping assembly is configured to interact with the second cam roller, wherein the second pumping assembly is offset from the first pumping assembly.

2. The fuel pump assembly of claim 1, further comprising a crankshaft configured to drive the fuel pump to draw fuel from a fuel tank to move the fuel toward 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 first pumping assembly includes a first plunger and a first plunger foot in confronting 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.

4. The fuel pump assembly according to claim 3, wherein: The second pumping assembly includes a second plunger and a second plunger foot in confronting 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 independently of reciprocating movement of the first plunger.

5. The fuel pump assembly of claim 4, wherein: 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 the at least one of the first plunger foot and the second plunger foot, respectively.

6. The fuel pump assembly of claim 4, wherein: 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 the at least one of the first plunger foot and the second plunger foot, respectively.

7. The fuel pump assembly of claim 4, 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 geometric configuration corresponding to the first flat geometric configuration of the at least one of the first plunger foot and the second plunger foot, respectively.

8. The fuel pump assembly of any one of claims 1-7, 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.

9. The fuel pump assembly of any one of claims 1-7, further comprising 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 of claim 4, wherein: The fuel pump further includes 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.

11. The fuel pump assembly of claim 10, wherein: The fuel pump further includes a third control mechanism configured to control a relative position of the second cam roller with respect to the second plunger together with the second control mechanism.

12. The fuel pump assembly according to any one of claims 1-7 and 10-11, 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 any one of claims 1-7 and 10-11, 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 of claim 4, further comprising at least one of a first tension member configured to bias the first plunger toward the first cam roller and a second tension member configured to bias the second plunger toward the second cam roller.

15. An engine system comprising: Engine block; a cylinder head coupled to the engine block; as well as A fuel system, the fuel system comprising: a plurality of fuel injectors located within the cylinder head; and A fuel pump, the fuel pump comprising: a camshaft having a cam lobe, 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 about an outer surface of the cam lobe, wherein the first cam roller and the second cam roller operate on the same cam lobe; a first pumping assembly configured to interact with the first cam roller; and A second pumping assembly is configured to interact with the second cam roller, wherein the second pumping assembly is offset from the first pumping assembly.

16. The engine system of claim 15, 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, the first pumping assembly and the second pumping assembly being located on opposite sides of a central cavity of the housing.

17. The engine system of claim 15 or 16, further comprising 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.

18. The engine system of claim 15 or 16, further comprising at least one of a first valve assembly configured to regulate the flow of low-pressure fluid into and out of the first pumping chamber and a second valve assembly configured to regulate the flow of low-pressure fluid into and out of the second pumping chamber.

19. The engine system according to claim 15 or 16, further comprising: 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 operatively coupled to the camshaft via a drive mechanism; as well as An electric lift pump is configured to draw the fuel from the fuel tank and supply the fuel to the fuel pump.

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