WO2022147125A1

WO2022147125A1 - Fuel pump

Info

Publication number: WO2022147125A1
Application number: PCT/US2021/065513
Authority: WO
Inventors: Rodney P. HAMMERLEIN; Michael A. Lucas
Original assignee: Cummins Inc.
Priority date: 2020-12-31
Filing date: 2021-12-29
Publication date: 2022-07-07

Abstract

An inlet valve for a high pressure fuel pump comprises a stator core having a first surface and an armature having a first surface facing the first surface of the stator core. The armature is configured for reciprocal motion with respect to the stator core. A valve plunger is coupled to the armature. One or both of the first surface of the stator core or the first surface of the armature include one or more recesses, such as an annular groove. Each recess is configured to reduce cavitation during operation of the inlet valve in the fuel pump.

Description

FUEL PUMP

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority benefit of U.S. Provisional Application No. 63/132,542 entitled “Fuel Pump,” filed on December 31, 2020, the entire contents and disclosures of which are incorporated herein by reference.

[0002] Additionally, this application is related to U.S. Provisional Application No. 63/132,721 entitled “Fuel Pump,” filed on December 31, 2020, the entire contents and disclosures of which are incorporated herein by reference.

FIELD

[0003] The present disclosure relates generally to pumps, such as fuel pumps. Disclosed embodiments include pumps with actuators configured for reduced cavitation wear.

BACKGROUND

[0004] Pumps may include a pumping plunger that is reciprocally driven within a pumping chamber to pressurize fluid in the chamber and 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, a magnetic flux field is produced 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.

[0005] 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.

[0006] Inlet valves with these features may produce an operating characteristic sometimes known as cavitation. As the pumping plunger reciprocation rate increases, so to 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 or damage on components such as the stator and/or armature.

SUMMARY

[0007] 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. One example is a valve for a fuel pump. In embodiments, the valve comprises a stator core having a first surface; an armature having a first surface facing the first surface of the stator core, wherein the armature is configured for reciprocal motion with respect to the stator core; and a valve plunger coupled to the armature. The valve also comprises one or more recesses in one or both of the first surface of the stator core or the first surface of the armature, wherein the recesses are configured to reduce cavitation during operation of the valve in the fuel pump.

[0008] In embodiments, the one or more recesses includes a plurality of recesses. The plurality of recesses may be circumferentially arranged.

[0009] In embodiments, the plurality of recesses are radially arranged. The plurality of recesses may comprise elongated grooves.

[0010] In any or all of the above embodiments, the one or more recesses are on the first surface of the stator core. In such embodiments, the first surface of the armature may be free from the one or more recesses. [0011] In any or all of the above embodiments, the one or more recesses are on the first surface of the armature. In any or all of the above embodiments, the first surface of the stator core is planar. In any or all of the above embodiments, the first surface of the armature is planar.

[0012] Examples include a fuel pump including the valve of any or all of the above embodiments. The fuel pump may be a high pressure fuel pump.

[0013] Examples include an inlet valve in accordance with any or all of the above embodiments.

[0014] Examples also include a stator core for a high pressure fuel pump inlet valve. The stator core may comprise a first surface; and one or more recesses in the first surface configured to reduce cavitation during operation of the stator in the fuel pump. In embodiments, the one or more recesses comprise an annular groove. In embodiments, the one or more recesses comprise a single annular groove. The stator core in accordance with any or all of the above embodiments may comprise a first surface that is planar.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a cross sectional illustration of a fuel pump including an inlet valve, in accordance with embodiments.

[0016] FIG. 2 is a detailed illustration of portions of the inlet valve shown in FIG. 1, in accordance with embodiments.

[0017] FIG. 3 is a cross sectional illustration of stator, in accordance with embodiments.

[0018] FIG. 4 is a cross sectional illustration of the stator, taken across lines 4 — 4 in FIG.

3, illustrating a surface of the core and an annular groove in accordance with embodiments.

[0019] FIG. 5 is an illustration of a surface of a stator core including a plurality of circumferentially arranged recesses in accordance with embodiments.

[0020] FIG. 6 is an illustration of a surface of a stator core including a plurality of radially-extending grooves in accordance with embodiments.

DETAILED DESCRIPTION

[0021] FIG. 1 is a diagrammatic illustration of a pump, such as a high pressure fuel pump 8, including an inlet valve 10 having a stator 12 and armature 14 in accordance with embodiments. FIG. 2 is a detailed illustration of portions of the inlet valve 10 including the stator 12 and armature 14. As described in greater detail below, stator 12 and/or armature 14 include one or more cavitation mitigating recesses or other structures such as groove 16 thereon. Cavitation mitigating structures such as groove 16 have been demonstrated to reduce the amount cavitation during operation of the pump 10 and/or wear on components such as stator 12 and/or armature 14 during any cavitation.

[0022] In addition to the inlet valve 10, the pump 8 includes a pump head 18 to which inlet valve is mounted. As shown, the pump head includes a pumping chamber 20 and a pumping plunger 22 configured for reciprocal motion within the pumping chamber. An inlet passage 24 including a transition zone 26, and an outlet passage 28, are in fluid communication with the pumping chamber 20. A plunger passage 30 configured to receive a valve plunger 32 extends into the transition zone 26 of the inlet passage 24. An actuator cavity vent passage 34 extends from the inlet passage 24 to a location fluidly coupled to an armature cavity 36 in the inlet valve 10. A check valve 38 is located in the outlet passage 28 in the illustrated embodiments.

[0023] Inlet valve 10 includes the stator 12, armature 14 and valve plunger 32. Stator 12 includes a core assembly 39 and a solenoid coil 44. FIG. 3 is an illustration of embodiments of the stator core assembly 39. The illustrated embodiments of core assembly 39 include a core 40 and sleeve section 42. Core 40 is formed from magnetically permeable material such as iron, and includes a spring pocket or recess 46. Coil 44 extends around the exterior of the core 40, and includes connector 45 for coupling electrical energy to the windings of the coil. Sleeve section 42 of the core assembly 39 is a cylindrical member defining the armature cavity 36, and includes a reluctance ring such as flux inhibiting sleeve or section 48 adjacent to the core 40, and a flux carrier sleeve or section 50 extending from the flux inhibiting section opposite the core. In embodiments, the flux inhibiting section 48 is formed from relatively magnetically impermeable material such as stainless steel, and the flux carrier section 50 is formed from relatively magnetically permeable material such as iron. The core 40 defines a first face or surface 52 that faces the armature cavity 36. In embodiments, the surface 52 is a generally planar surface.

[0024] A retainer 54 engages a lip on the flux carrier section 50 of the core assembly 39 to secure the stator 12 to the pump head 18. The coil 44 is secured to the core 40 of the core assembly 39 by a fastener such as nut 55. Retainer 54 and nut 55 may be formed from relatively magnetically permeable materials in embodiments. As shown in FIGs. 1 and 2, the armature cavity 36 of the stator 12 is in fluid communication with the plunger passage 30 and the actuator cavity vent passage 34 when the stator 12 is mounted to the pump head 18. Fuel from the inlet passage 24 may therefore flow into the armature cavity 36 during operation of the pump 8.

[0025] Armature 14 is a disk-shaped member having a first face or surface 60 on a first side and a second face or surface 62 on a second, opposite side. The first surface 60 faces the first surface 52 of the core 40. In embodiments, the first surface 60 and second surface 62 of the armature are generally planar surfaces. The armature 14 is configured for reciprocal motion in the armature cavity 36. During this reciprocal motion the first surface 60 of the armature 14 moved toward and away from the first surface 52 of the core 40. The illustrated embodiments of the armature 14 includes through holes 64 through which fuel is allowed to flow into either side of the armature to reduce pressure imbalances around the armature. Fuel that flows through the armature 14 may enter the spring recess 46.

[0026] Valve plunger 32 is mounted to the armature 14 and extends through the plunger passage 30. A head 70 on an end of the valve plunger 32 is located in the pumping chamber 20. In the embodiments shown in FIG. 1, pump head 18 defines a shoulder 72 at the intersection of the transition zone 26 of the inlet passage 24 and the pumping chamber 20. A sealing surface 74 on the side of the plunger head 70 can engage and disengage from the shoulder 72 of the pump head 18 during operation of the pump 8. The illustrated embodiment of inlet valve 10 also includes an annular flux inhibitor or spacer 76 around the valve plunger 32 on the side of the armature 14 adjacent the second surface 62. Spacer 76 may be formed from relatively magnetically impermeable materials, such as stainless steel for example, in embodiments.

[0027] A biasing member such as spring 80 is located in the spring recess 46. The spring 80 biases the armature 14 away from the core 40 of stator 12 (i.e., in a downwardly direction in FIGs. 1 and 2) to a first position when the coil 44 is not actuated or energized. A gap will be present between the first surface 52 of the core 40 and the first surface 60 of the armature 14 when the armature is in the first position. When the armature 14 is in the first position, the valve plunger 32 is driven by the armature to an open position with the sealing surface 74 of the head 70 spaced apart from the shoulder 72 of the pump head 18, thereby fluidly coupling the inlet passage 24 to the pumping chamber 20. When the coil 44 of the stator 12 is electrically actuated or energized, it generates a magnetic flux field that acts on armature 14. The forces generated by the magnetic field are sufficient to overcome the bias force of the spring 80, and causes the armature 14 to retract (i.e., move in a direction upwardly in FIGs. 1 and 2) to a second position. When in the second position, the size of the gap between the armature 14 and core 40 is reduced from its size when the armature was in the first position, and the first surface 52 of the core 40 is closer to the first surface 60 of the armature than when the armature was in the first position. In embodiments, the first surface 60 of the armature 14 is in close proximity to the first surface 52 of the stator core 40 when the armature is in the second position to encourage the flow of the magnetic field across the gap. When the armature 14 is in the second position, the valve plunger 32 is driven by the armature to a closed position with the sealing surface 74 of the head 70 engaged with the shoulder 72 of the pump head 18 (i.e., the positions shown in FIGs. 1 and 2), thereby fluidly isolating the inlet passage 24 from the pumping chamber 20. In embodiments, components of the stator 12 such as armature 14, core 40, nut 55, retainer 53 and sleeve 42 may be configured to concentrate portions of the magnetic flux field through the armature and across the gap to the core.

[0028] A drive mechanism (not shown) reciprocally drives the pumping plunger 22 within the pumping chamber 20 during operation of the pump 8. Conventional or otherwise known drive mechanisms can be used for this purpose. In embodiments, for example, such drive mechanisms include a cam coupled to an engine to reciprocally drive the pumping plunger. An electrical control system (not shown) controls the operation of the inlet valve 10 as the pumping plunger 22 reciprocates within the pumping chamber 20 to cause the pumping plunger to cyclically draw fuel into the pumping chamber, trap the fuel in the pumping chamber and force the fuel out of the pumping chamber through the outlet passage 28. In particular, as the reciprocating pumping plunger 22 moves to make the pumping chamber 20 smaller with the pumping chamber filled with fuel and the valve plunger 32 in the closed position by actuation of the inlet valve 10, the fuel pressure in the pumping chamber rises until the check valve 38 opens and allows the fuel to flow out of the pumping chamber through the outlet passage into a downstream volume (e.g., a common rail fuel accumulator, not shown). This flow continues until the reciprocating pumping plunger 22 reverses direction to make the pumping chamber 20 larger and the check valve 38 closes and the inlet valve 10 is de-actuated to allow the valve plunger 32 to move to the open position. Fuel is then able to flow into the pumping chamber 20 through the inlet passage 24. When the pumping chamber 20 is filled, the reciprocating pumping plunger 22 reverses direction to make the pumping chamber volume smaller, and the inlet valve 10 is actuated to drive the valve plunger 32 to the closed position and the cycle repeats. The valve plunger 26 is thereby driven in synchronization with the pumping plunger 22 by the inlet valve 10, so as the pumping plunger reciprocation rate increases or decreases, so too does the rate at which the inlet valve 10 opens and closes.

[0029] As noted above, one or both of the armature 14 and core 40 include cavitation mitigation structures configured to reduce or prevent cavitation that might otherwise be present during the operation of the pump 8. Wear or damage that may be produced by cavitation is thereby reduced as well. In embodiments, the cavitation mitigation structures comprise one or more recesses in the first surface 60 of the armature 14 and/or the first surface 52 of the core 40. Wear on components such as the armature 14 and/or core 40 during operation of the pump 8 can be reduced by the cavitation mitigation structures. FIGs. 1-4, for example, illustrate a cavitation mitigation structure in the form of an annular groove 16 in the first surface 52 of the core 40. Although a single groove 16 is shown in FIGs. 1-4 for purposes of example, other embodiments (not shown) include two or more grooves. Groove 16 is continuous in the embodiments shown in FIGs. 1-4. FIG. 5 illustrates embodiments of a core 40’ including a first surface 52’ and a discontinuous annular groove 16’ comprising a plurality of recesses 90. FIG. 6 illustrates embodiments of a core 40” including a first surface 52” and a cavitation mitigation structure comprising a plurality of radially extending linear grooves 92. The linear grooves 92 are circumferentially arranged on the first surface 52”. Dimensions of the cavitation mitigation structures, such as the depth and/or length of the grooves 16 and 92, the number of structures such as grooves 16,92 and recesses 90, and the location of the structures on the first surface 52, can be selected to optimize the cavitation mitigation functionality provided by the structures. In embodiments, the cavitation mitigation structures are configured to minimize or not substantially impact the magnetic flux field extending through the armature 14 and core 40 so as to prevent or not substantially impact performance capabilities of the inlet valve 10 relating to the ability of the coil 44 to drive the armature. Although shown on the first surface 52 of the core 40 for purposes of example in FIGs. 1-6, other embodiments (not shown) may additionally or alternatively include cavitation mitigation structures on the first surface 60 of the armature 14. Testing has demonstrated that cavitation minimization structures of the types described above may significantly reduce wear on components such as the core 40 during actuation of the inlet valve 10. [0030] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. It is contemplated that features described in association with one embodiment are optionally employed in addition or as an alternative to features described in or associated with another embodiment. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

CLAIMS What is claimed is:

1. A valve for a fuel pump, comprising: a stator core having a first surface an armature having a first surface facing the first surface of the stator core, wherein the armature is configured for reciprocal motion with respect to the stator core; a valve plunger coupled to the armature; and one or more recesses in one or both of the first surface of the stator core or the first surface of the armature, wherein the recesses are configured to reduce cavitation during operation of the valve in the fuel pump.

2. The valve of claim 1 wherein the one or more recesses includes an annular groove.

3. The valve of claim 1 wherein the one or more recesses includes a plurality of recesses.

4. The valve of claim 3 wherein the plurality of recesses are circumferentially arranged.

5. The valve of claim 1 wherein the plurality of recesses are radially arranged.

6. The valve of claim 5 wherein the plurality of recesses comprise elongated grooves.

7. The valve of any of claims 1-6 wherein the one or more recesses are on the first surface of the stator core.

8. The valve of claim 7 wherein the first surface of the armature is free from the one or more recesses.

9

9. The valve of any of claims 1-6 wherein the one or more recesses are on the first surface of the armature.

10. The valve of any of claims 1-9 wherein the first surface of the stator core is planar.

11. The valve of any of claims 1-10 wherein the first surface of the armature is planar.

12. A fuel pump including the valve of any of claims 1-11.

13. A high pressure fuel pump in accordance with claim 12.

14. The valve of any of claims 1-13 wherein the valve is an inlet valve.

15. A stator core for a high pressure fuel pump inlet valve, comprising: a first surface; and one or more recesses in the first surface configured to reduce cavitation during operation of the stator in the fuel pump.

16. The stator core of claim 15 wherein the one or more recesses comprise an annular groove.

17. The stator core of claim 14 wherein the one or more recesses comprise a single annular groove.

18. The stator core of any of claims 15-17 wherein the first surface is planar.