FUEL PUMP

A valve includes a valve body having a valve plunger barrel formed therein and configured to be mounted to a pump head of a fuel pump, a valve plunger arranged to perform reciprocal motion with respect to the valve plunger barrel, a drive assembly configured to cause the valve plunger to perform reciprocal motion, and a spacer configured to couple to the valve plunger to perform reciprocal motion together with the valve plunger and configured to interface with the pump head. The spacer has a spacer body with first and second opposing spacer surfaces and with a central aperture extending from the first to the second spacer surface and configured to receive the valve plunger therethrough. At least one of the first and second spacer surfaces includes one or more grooves recessed into the spacer body to reduce or inhibit cavitation of the interface of the spacer and pump head.

TECHNICAL FIELD

The present disclosure related generally to pumps, such as fuel pumps and, more particularly, to pumps with component design features configured for reduced cavitation wear.

BACKGROUND

Pumps may include a pumping plunger that is reciprocally driven within a pumping chamber to pressurize a fluid in the pumping chamber and to cause the fluid to exit the chamber through an outlet passage. Inlet valves may be used to control the flow of fluid from an inlet passage into the pumping chamber. Inlet valves of high pressure fuel pumps, for example, may include a valve plunger that reciprocally moves between a closed position, causing the inlet passage to be fluidly sealed with respect to the pumping chamber, and an open position, causing the inlet passage to be fluidly coupled to the pumping chamber. Inlet valves of these types may include solenoid-type actuators having stators and armatures for actuating the valve plunger. The armature may be coupled to the valve plunger. A biasing member such as a spring may bias the valve plunger to the open position at which the armature is spaced apart from the stator core by a gap. When the stator is energized by the application of electrical energy to coils around the stator core, it produces a magnetic flux field that causes the armature to be drawn toward the stator core against the bias force of the spring, thereby driving the valve plunger to the closed position. When the stator is de-energized, the spring drives the valve plunger back to the open position.

In high-pressure fuel pumps of these types, the chamber in which the armature moves may not be sealed from the source of fuel. For example, the armature chamber may be in fluid communication with the inlet passage, and fuel may flow into the gap between the armature and core. The armature and valve plunger are typically driven at high rates. To enhance the magnetic flux field coupling between the stator and armature and facilitate performance of the inlet valve, the armature and stator can be positioned in relatively close proximity to one another.

Inlet valves with these features may produce an operating characteristic sometimes known as cavitation. As the pumping plunger reciprocation rate increases, so too does the rate at which the inlet valve opens and closes. The armature and valve plunger therefore move between the open and closed positions at relatively high velocities. As the armature moves toward and away from the stator core, cyclic waves of high-pressure fuel and low-pressure fuel may be created around the armature (e.g., in the gap between the armature and core). The relatively low pressures produced during the low-pressure portions of the cycle may cause the vaporization of fuel. During the high-pressure portions of the cycle, any vaporized fuel may collapse or return to liquid form. Energy released during these fuel phase changes may cause wear on components such as the stator and/or armature.

There remains a continuing need for improved pumps, such as high-pressure fuel pumps. In particular, there is a need for improvements to mitigate cavitation or the wear that may be produced by such cavitation. Structures and methods that can efficiently provide enhancements of these types would be especially desirable.

SUMMARY

Disclosed examples include valves for pumps, such as inlet valves for high pressure fuel pumps, with structures to reduce or minimize cavitation and associated wear on the valve. A valve for a fuel pump can include a valve body, a plunger, a drive assembly, and a spacer. The valve body can have a plunger barrel formed therein and can be configured to be mounted to a pump head of the fuel pump. The plunger can be arranged to perform reciprocal motion with respect to the plunger barrel. The drive assembly can be configured to cause the plunger to perform reciprocal motion. The spacer can be configured to couple to the plunger so as to perform reciprocal motion together with the plunger and can be configured to interface with the valve body. The spacer can have a spacer body with a first face, a second face that is opposite the first face, and a central aperture that extends from the first face to the second face. The spacer can be configured to receive the plunger through the central aperture. At least one of the first face and the second face can include one or more grooves that are recessed into the spacer body so as to reduce or inhibit cavitation of the spacer where the pump head interfaces with the spacer.

In examples, the spacer body can be a closed ring shape such that the spacer surrounds a portion of plunger that is coupled to the spacer. The spacer can be coupled to the plunger so as to perform reciprocal motion together with the plunger and configured to interface with the valve body. The spacer can have a spacer body with a first face, a second face that is opposite the first face, and a central aperture that extends from the first face to the second face. The spacer can be configured to receive the plunger through the central aperture. At least one of the first face and the second face can include one or more grooves that are recessed into the spacer body so as to reduce or inhibit cavitation of the spacer where the pump head interfaces with the spacer.

A plunger assembly can include a plunger and a spacer. The plunger can be configured to perform, via a drive assembly, reciprocal motion within a valve body. The plunger can be coupled to a portion of the drive assembly. In examples, a first shoulder portion of the at least one shoulder portion can include at least one flattened portion extending in a direction along a central axis of the elongate plunger body so as to form a fluid flow passage between the plunger barrel, in which the plunger is arranged, and the at least one flattened portion. The fluid flow passage can be in fluid communication with a groove of the one or more grooves.

In examples, both the first and second faces can include the one or more grooves. In examples, the one or more grooves at both the first and second faces can include a single annular groove. In examples, the one or more grooves can include a single annular groove. In examples, the one or more grooves can include a plurality of grooves. In examples, the plurality of grooves can be circumferentially arranged. In examples, the plurality of grooves can be radially arranged. In examples, the one or more grooves can include a plurality of grooves that is circumferentially arranged or radially arranged.

In examples, the drive assembly can be an electromagnetic drive mechanism comprising a stator core and an armature coupled to the plunger. In examples, the plunger can include an elongate plunger body with a main portion and at least one shoulder portion. The spacer can be positioned between the armature and the at least one shoulder portion of the plunger. The main portion can form a minor diameter of the elongate plunger body. The at least one shoulder portion can form a major diameter of the elongate plunger body.

The present disclosure includes methods of reducing cavitation in a valve for a fuel pump. The method can include reciprocating a plunger within a valve body of the valve. The method can include directing, as the plunger reciprocates within the valve, a fluid to flow past the plunger and into one or more grooves in a spacer coupled to the plunger and configured to interface with the valve body. The method can include allowing small vapor-filled cavities caused rapid changes of pressure in the fluid from the plunger reciprocating within the valve body to collapse to collapse within the one or more grooves so as to inhibit cavitation of the spacer.

In examples of the method, the fluid can flow past the plunger and into the one or more grooves via fluid flow passage formed between the valve body and at least one flattened portion of the plunger. The at least one flattened portion can extend in a direction along a central axis of an elongate plunger body of the plunger.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the present disclosure, reference is now made to the embodiments illustrated in the drawings, which are described below. The exemplary embodiments disclosed herein are not intended to be exhaustive or to limit the disclosure to the precise form disclosed in the following detailed description. Rather, these exemplary embodiments were chosen and described so that others skilled in the art may utilize their teachings. It is not beyond the scope of this disclosure to have a number (e.g., all) the features in a given embodiment to be used across all embodiments.

FIG.1shows a diagrammatic illustration of a pump1, such as a high-pressure fuel pump, including an inlet valve10that has a valve body11, a valve plunger13, a drive assembly15, and a spacer17. As explained in greater detail below, the valve body11can have a valve plunger barrel19formed therein, the valve plunger13can be arranged to perform reciprocal motion with respect to the valve plunger barrel19, and the drive assembly15can be configured to cause the valve plunger13to perform reciprocal motion (e.g., within the valve plunger barrel19). In examples, the drive assembly15can be an electromagnetic drive assembly15comprising a stator21with a stator core23and an armature25coupled to the valve plunger13. In this regard, for instance, when the drive assembly15includes a stator21and an armature25, the valve plunger13can be coupled to a portion of the drive assembly15. Under these circumstances, the valve plunger13can be configured to perform, via the drive assembly15, reciprocal motion within the valve body11. Together, in examples, the valve plunger13, the spacer17, and optionally the armature25can form a valve plunger13assembly.

FIG.2shows a detailed illustration of portions of the inlet valve10, including the valve plunger13and the spacer17. As described in greater detail below, each of the valve plunger13and stator21can include one or more cavitation mitigation measures (e.g., a recess27or other structures such as a groove29or a flattened portion31) thereon. Such cavitation mitigating structures (e.g., the groove29and the flattened portion31) have been demonstrated to reduce an amount cavitation during operation of the pump1and/or wear on components such as the spacer17during any cavitation.

With reference toFIGS.1and2, in addition to the inlet valve10, the pump1includes a pump head33to which inlet valve10can be configured to be mounted. As shown, the pump head33includes a pumping chamber35and a pumping plunger37configured for reciprocal motion within the pumping chamber35. An inlet passage39including a transition zone41, and an outlet passage43, are in fluid communication with the pumping chamber35. A valve plunger barrel19configured to receive a valve plunger13extends into the transition zone41of the inlet passage39. An actuator cavity vent passage45extends from the inlet passage39to a location fluidly coupled to an armature cavity47in the inlet valve10. A check valve51is located in the outlet passage43in the illustrated examples.

As noted above, the inlet valve10includes the stator21, armature25and valve plunger13. The stator21includes a core assembly53and a solenoid coil49.FIG.3shows an illustration of examples of the core assembly53. The illustrated examples of core assembly53include a stator core23and a sleeve section55. The stator core23is formed from magnetically permeable material such as iron and includes a spring pocket57. The solenoid coil49extends around the exterior of the stator core23and includes a connector58(seeFIG.1) for coupling electrical energy to the windings of the coil. The sleeve section55of the core assembly53is a cylindrical member defining the armature cavity47and includes a reluctance ring such as a flux inhibiting section59(e.g., a flux inhibiting sleeve) adjacent to the stator core23, and a flux carrier section61(e.g., a flux carrier sleeve) extending from the flux inhibiting section59opposite the stator core23. In examples, the flux inhibiting section59is formed from relatively magnetically impermeable material, such as stainless steel, and the flux carrier section61is formed from relatively magnetically permeable material, such as iron. The stator core23defines a first surface63that faces the armature cavity47. In examples, as shown here, the first surface63is a generally planar surface.

With reference toFIGS.1-3, a retainer65engages a lip on the flux carrier section61of the core assembly53to secure the stator21to the pump head33. The solenoid coil49is secured to the stator core23of the core assembly53by a fastener such as nut67. In examples, the retainer65and nut67may be formed from relatively magnetically permeable materials. As shown inFIGS.1and2, the armature cavity47of the stator21is in fluid communication with the valve plunger barrel19and the actuator cavity vent passage45when the stator21is mounted to the pump head33. Fuel from the inlet passage39may therefore flow into the armature cavity47during operation of the pump1.

The armature25is a disk-shaped member having a first surface69on a first side and a second surface71on a second, opposite side. The first surface69faces the first surface63of the stator core23. In examples, the first surface69and second surface71of the armature25are generally planar surfaces. The armature25is configured for reciprocal motion in the armature cavity47. During this reciprocal motion, the first surface69of the armature25is moved toward and away from the first surface63of the stator core23. The illustrated examples of the armature25include through holes73through which fuel is allowed to flow into either side of the armature25to reduce pressure imbalances around the armature25. Fuel that flows through the armature25may enter the spring pocket57. The illustrated embodiment of inlet valve10also includes a spacer17(e.g., an annular flux inhibitor) around the valve plunger13on the side of the armature25adjacent the second surface71. The spacer17may be formed from relatively magnetically impermeable materials, such as stainless steel for example, in examples. More details about the spacer17will be discussed below.

The valve plunger13is mounted to the armature25and extends through the valve plunger barrel19. A valve plunger head75on an end of the valve plunger13is located in the pumping chamber35. In the examples shown inFIG.1-3, the pump head33defines a pump shoulder77at the intersection of the transition zone41of the inlet passage39and the pumping chamber35. A sealing surface79on the side of the valve plunger head75can engage and disengage from the pump shoulder77of the pump head33during operation of the pump1. More details about the valve plunger13will be discussed below.

More details about the components of the inlet valve10will be further discussed below. More specifically, after discussion of the drive mechanism immediately below, later discussion herein (e.g., with respect toFIGS.4-6andFIGS.7-9) will provide more details about the cavitation mitigation measures featured in the spacer17and the valve plunger13.

With continued reference toFIGS.1-3, a biasing member, such as a spring81, is located in the spring pocket57. The spring81biases the armature25away from the stator core23of the stator21(e.g., in a downward direction inFIGS.1and2) to a first position when the solenoid coil49is not actuated or energized. A gap will be present between the first surface63of the stator core23and the first surface69of the armature25when the armature25is in the first position. When the armature25is in the first position, the valve plunger13is driven by the armature25to an open position with the sealing surface79of the valve plunger head75spaced apart from the pump shoulder77of the pump head33, thereby fluidly coupling the inlet passage39to the pumping chamber35. When the solenoid coil49of the stator21is electrically actuated or energized, it generates a magnetic flux field that acts on the armature25. The forces generated by the magnetic field are sufficient to overcome the bias force of the spring81, and causes the armature25to retract (e.g., move in an upward direction inFIGS.1and2) to a second position. When in the second position, the size of the gap between the armature25and stator core23is reduced from its size when the armature25was in the first position, and the first surface63of the stator core23is closer to the first surface69of the armature25than when the armature25was in the first position. In examples, the first surface69of the armature25is proximal to the first surface63of the stator core23when the armature25is in the second position to encourage the flow of the magnetic field across the gap. When the armature25is in the second position, the valve plunger13is driven by the armature25to a closed position with the sealing surface79of the valve plunger head75engaged with the pump shoulder77of the pump head33(e.g., the positions shown inFIGS.1and2), thereby fluidly isolating the inlet passage39from the pumping chamber35. In examples, components of the stator21such as armature25, stator core23, nut67, retainer65and sleeve section55may be configured to concentrate portions of the magnetic flux field through the armature25and across the gap to the stator core23.

A drive mechanism (not shown) reciprocally drives the pumping plunger37within the pumping chamber35during operation of the pump1. Conventional or otherwise known drive mechanisms can be used for this purpose. In examples, for example, such drive mechanisms include a cam coupled to an engine to reciprocally drive the pumping plunger37. An electrical control system (not shown) controls the operation of the inlet valve10as the pumping plunger37reciprocates within the pumping chamber35to cause the pumping plunger37to cyclically draw fuel into the pumping chamber35, trap the fuel in the pumping chamber35and force the fuel out of the pumping chamber35through the outlet passage43. In particular, as the pumping plunger37moves to make the pumping chamber35smaller with the pumping chamber35filled with fuel and the valve plunger13in the closed position by actuation of the inlet valve10, the fuel pressure in the pumping chamber35rises until the check valve51opens and allows the fuel to flow out of the pumping chamber35through the outlet passage43into a downstream volume (e.g., a common rail fuel accumulator, not shown). This flow continues until the pumping plunger37reverses direction to make the pumping chamber35larger and the check valve51closes and the inlet valve10is de-actuated to allow the valve plunger13to move to the open position. Fuel is then able to flow into the pumping chamber35through the inlet passage39. When the pumping chamber35is filled, the pumping plunger37reverses direction to make the pumping chamber35volume smaller, and the inlet valve10is actuated to drive the valve plunger13to the closed position, and the cycle repeats. The valve plunger13is thereby driven in synchronization with the pumping plunger37by the inlet valve10, so as the pumping plunger37reciprocation rate increases or decreases, so too does the rate at which the inlet valve10opens and closes.

As noted above, with reference toFIGS.1-3, one or more components of the inlet valve10can include cavitation mitigation structures that are configured to reduce or prevent cavitation that might otherwise occur at those components during operation of the pump1. In examples, as further described below, the cavitation mitigation structures can comprise one or more grooves in a spacer body83of the spacer. The spacer body83can have a first spacer surface85, a second spacer surface87that is opposite the first spacer surface85, and a central aperture89that extends from the first spacer surface85to the second spacer surface87. In addition, or in alternative, the cavitation mitigation structures can comprise one or more recesses27in any one or each of the first surface69of the armature25and the first surface63of the stator core23. In this regard, due to the cavitation mitigation structures, wear on such components (e.g., the spacer17, the armature25, and the stator core23) of the inlet valve10during operation of the pump1can be reduced by the cavitation mitigation structures.FIGS.4and5, for example, illustrate a cavitation mitigation structure in the form of an annular groove29in the first spacer surface85and second spacer surface87.

As also noted above, referring toFIGS.1,2,4, and5, the spacer17can be coupled between the armature25and a portion of the valve plunger13and can be formed from relatively magnetically impermeable materials (e.g., certain steels). So configured, the spacer17may assist in operation of the inlet valve10by ensuring that during operation thereof, the armature25does not magnetically couple to the pump head33such that the valve plunger13no longer reciprocates and, thus, causes the inlet valve10to remain opened. For instance, the spacer17can be configured to couple to the valve plunger13so as to perform reciprocal motion together with the valve plunger13and can be configured to interface with the pump head33. The spacer17can be configured to receive the valve plunger13through the central aperture89.

At least one of the first spacer surface85and the second spacer surface87can include one or more grooves29that are recessed into the spacer body83so as to reduce or inhibit cavitation of the spacer17where the spacer17interfaces with the pump head33. The one or more grooves29can take a variety of forms. In examples, the one or more grooves29can include a single annular groove29at the first spacer surface85or the second spacer surface87. In examples, both the first and second spacer surfaces85,87can include the one or more grooves29. In examples, the one or more grooves29at both the first and second spacer surfaces85,87can include a single annular groove29. In examples, the one or more grooves29can include a plurality of grooves29. In examples, the plurality of grooves29can be circumferentially arranged, concentrically arranged, or both. In examples, the plurality of grooves29can be radially arranged. In examples, the one or more grooves29can include a plurality of grooves29that is circumferentially arranged or radially arranged.

Valve plunger13is mounted to the armature25and extends through the valve plunger barrel19. As best shown inFIG.6, the valve plunger13can include an elongate valve plunger body91with a main portion93and at least one shoulder portion95. The spacer17can be positioned between the portion of the drive assembly and the at least one shoulder portion95of the valve plunger13. The main portion93can form a minor diameter D2of the elongate valve plunger body91, and the at least one shoulder portion95can form a major diameter D1of the elongate valve plunger body91. Each shoulder portion95in the at least one shoulder portion95can include at least one flattened portion31, which can extend in a direction along a central axis CA of the elongate valve plunger body91. Under these circumstances, fluid flow passage97can be formed between the valve plunger barrel19of the valve body11and at least one flattened portion31of the elongate valve plunger body91. The fluid flow passage97can be in fluid communication with a groove29of the one or more grooves29.

In examples, the spacer body83can be a closed ring shape such that the spacer17surrounds a portion of plunger that is coupled to the spacer17.

Although a single groove29for the spacer17is shown at both the first and second spacer surfaces85,87inFIGS.1,2,4, and5for purposes of example, other examples have recesses27in the form of an arrangement of grooves29,99at the first spacer surface85,85′,85″ only as shown inFIG.7-9. What is more, these arrangements can have two or more (e.g., a plurality of) grooves29′,99as shown inFIGS.8and9.FIG.7shows a plan view of the spacer17with a first arrangement of grooves29where the first spacer surface85has a single annular grooves29.FIG.8shows a plan view of the spacer17′ with a second arrangement of grooves29′ where the first spacer surface85′ has a plurality of rounded grooves29.FIG.9shows a plan view of the spacer17″ with a second arrangement of grooves99where the first spacer surface85″ has a plurality of linear grooves99. Of course, these arrangements (e.g., the first, second, and third arrangements) are just some of many examples and can be included at the second spacer surface87only or both the first spacer surface85,85′,85″ and the second spacer surfaces87in examples.

A variety of designs for recesses27in the spacer17can be achieved while still inhibiting or reducing cavitation. Groove29is continuous in the examples shown inFIG.7.FIG.8illustrates examples of a spacer17′ including a first spacer surface85′ and a discontinuous annular groove29′ comprising a plurality of rounded grooves29′.FIG.9illustrates examples of a spacer17″ including a first spacer surface85″ and a cavitation mitigation structure comprising a plurality of radially extending linear grooves99. The linear grooves99are circumferentially arranged on the first spacer surface85″. Dimensions of the recesses27, such as the depth and/or length of the grooves29,29′ and linear grooves99, the number of structures such as the grooves29,29′ and linear grooves99, and the location of these structures on the first spacer surface85,85′,85″, can be selected to optimize the cavitation mitigation functionality provided by the structures. In examples, the recesses27are configured to minimize or not substantially impact the magnetic flux field extending through the spacer17,17′,17″ so as to prevent or not substantially impact performance capabilities of the inlet valve relating to the ability of the coil to drive the armature and thereby to drive the valve plunger. Although shown on the first spacer surface85,85′,85″ of the spacer17,17′,17″ for purposes of example inFIGS.7-9, recesses27in other examples (e.g., shown inFIGS.1,2,4, and5) may additionally or alternatively include these recesses27on the second spacer surface87. Testing has demonstrated that cavitation minimization structures of the types described above may significantly reduce wear on components such as the spacer17,17′,17″ during actuation of the inlet valve.

The present disclosure includes methods of reducing cavitation in a valve for a fuel pump. For example,FIG.10shows a flowchart of such a method300. At step302, the method300can include reciprocating a valve plunger within a valve body of the valve. At step304, the method300can include directing, as the valve plunger reciprocates within the valve, a fluid to flow past the valve plunger and into one or more grooves in a spacer coupled to the valve plunger and configured to interface with the valve body. At step306, the method300can include allowing small vapor-filled cavities caused by rapid changes of pressure in the fluid from the valve plunger reciprocating within the valve body to collapse within the one or more grooves so as to inhibit cavitation. These steps can be repeated (e.g., for as long as the pump is operating) as indicated by a feedback loop308. The method300may end, for example, when the pump ceases to operate.

In examples of the method300, the fluid can flow past the valve plunger and into the one or more grooves via fluid flow passage formed between the valve body and at least one flattened portion of the valve plunger. The at least one flattened portion can extend in a direction along a central axis of an elongate valve plunger body of the valve plunger.

It is well understood that methods that include one or more steps, the order listed is not a limitation of the claim unless there are explicit or implicit statements to the contrary in the specification or claim itself. It is also well settled that the illustrated methods are just some examples of many examples disclosed, and certain steps may be added or omitted without departing from the scope of this disclosure. Such steps may include incorporating devices, systems, or methods or components thereof as well as what is well understood, routine, and conventional in the art.

In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art with the benefit of the present disclosure to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.