Fuel pump having inlet valve assembly

Abstract

The fuel pump (18) includes a fuel pump housing (28) having a pumping chamber (38) defined therein and an inlet valve bore (28a) extending to an exterior of the fuel pump housing (28) along an inlet valve bore axis (28b). A pumping plunger (34) reciprocates within the plunger bore such that a suction stroke of the pumping plunger (34) increases a volume of the pumping chamber (38) and a compression stroke of the pumping plunger (34) decreases a volume of the pumping chamber (38). An inlet valve assembly (40) selectively provides and prevents fluid communication between an inlet (20a) of the fuel pump (18) and the pumping chamber (38). The inlet valve assembly (40) includes an inner housing (82) received within the inlet valve bore (28a) such that an outer periphery of the inner housing (82) is sealed to an inner periphery of the inlet valve bore (28a). An outer housing (94) circumferentially surrounds the inner housing (82). An annular chamber (96) is defined radially between the inner housing (82) and the outer housing (94) and axially between the outer housing (94) and the fuel pump housing (28). A sealing annulus (98) is positioned within the annular chamber (96) such that it is axially compressed relative to the pump housing (28) and the outer housing (94).

Description

[Technical field]

[0001] The present invention relates to fuel pumps for supplying fuel to internal combustion engines, and more particularly to such fuel pumps including inlet valve assemblies, and even more particularly to such fuel pumps with inlet valve assemblies that are robust against fluid exposure in the external environment. [Background technology]

[0002] Fuel systems in modern internal combustion engines fueled by gasoline, particularly for use in the automotive market, employ gasoline direct injection (GDi) in which fuel injectors are provided that inject fuel directly into the combustion chambers of the internal combustion engine. In such systems employing GDi, fuel from a fuel tank is delivered under relatively low pressure by a low-pressure fuel pump, typically an electric fuel pump located in the fuel tank. The low-pressure fuel pump delivers fuel to a high-pressure fuel pump, typically including a fuel pump housing and a pumping plunger that is reciprocated within the fuel pump housing by the camshaft of the internal combustion engine. The reciprocating motion of the pumping plunger further pressurizes the fuel for delivery to the fuel injectors that inject fuel directly into the combustion chambers of the internal combustion engine. During operation, the internal combustion engine is subject to changing demands for output torque. To accommodate the changing output torque demands, the mass of fuel delivered by each stroke of the pumping plunger must also be changed. One approach to vary the delivery of fuel by the high-pressure fuel pump is to use an inlet valve assembly that includes a solenoid. The inlet valve assembly can allow a full charge of fuel to enter the pumping chamber during each intake stroke, but the solenoid can operate the inlet valve assembly to remain open during a portion of the pumping plunger's compression stroke to allow some fuel to spill back toward the source. The remainder of the compression stroke then pressurizes the fuel when the solenoid is operated to close the inlet valve assembly, discharging it to the fuel injector. It is known for the inlet valve assembly to be received within a bore in the fuel pump housing and extend outside the fuel pump housing. To prevent fuel leakage, a sealing arrangement is provided to seal between the fuel pump housing and the inlet valve assembly. In some configurations, such as that provided in U.S. Patent No. 5,399,233 to Stritzel et al., a portion of the inlet valve assembly is welded to the fuel pump housing to provide a sealed interface. In other configurations, such as that provided in U.S. Patent No. 5,399,233 to Usui et al., the inlet valve assembly can be sealed to the fuel pump housing by providing an O-ring radially between the inlet valve assembly and the fuel pump housing.In each case, a sealing arrangement is provided between the inlet valve assembly and the fuel pump housing to prevent fuel from exiting the fuel pump housing. However, the portion of the inlet valve assembly that extends outside the fuel pump housing may be exposed to environmental conditions that may cause liquids, such as rainwater or salt water from de-iced roads, to deposit on the outlet control valve. These liquids may seep into the interface of the components that form the inlet control valve or solenoid and over time may damage one or more of the components of the inlet control valve or solenoid, which may result in undesirable operation of the inlet control valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 10,947,942 [Patent Document 2] U.S. Patent No. 7,401,594 Summary of the Invention [Problem to be solved by the invention]

[0004] What is needed is a fuel pump that minimizes or eliminates one or more of the disadvantages set forth above. [Means for solving the problem]

[0005] In accordance with one aspect of the invention, a fuel pump includes a fuel pump housing having a pumping chamber defined therein and an inlet valve bore extending to an exterior of the fuel pump housing along an inlet valve bore axis; a pumping plunger reciprocating within the plunger bore such that an intake stroke of the pumping plunger increases a volume of the pumping chamber and a compression stroke of the pumping plunger decreases a volume of the pumping chamber; and an inlet valve assembly 1) selectively providing fluid communication between the fuel pump inlet and the pumping chamber; and 2) selectively preventing fluid communication between the fuel pump inlet and the pumping chamber. The inlet valve assembly includes an inner housing that is received in the inlet valve hole such that the inner housing extends to the outside of the fuel pump housing and such that an outer periphery of the inner housing is sealed to an inner periphery of the inlet valve hole so that fuel is prevented from passing radially between the inner housing and the inlet valve hole to the outside of the fuel pump housing; an outer housing that is positioned outside the fuel pump housing and circumferentially surrounds the inner housing, an annular chamber being defined radially between the inner housing and the outer housing and axially between the outer housing and the fuel pump housing; and a sealing annulus that is made of an elastomeric material, has an annular shape, and is positioned in the annular chamber so as to be axially compressed against the fuel pump housing and the outer housing.

[0006] A fuel pump as described herein having a sealing annulus minimizes the possibility of liquid from the external environment reaching elements of the inlet valve assembly, which could result in undesirable operation if it does reach those elements.

[0007] The inlet valve assembly may include a solenoid assembly that may include the inner housing, the outer housing, a pole piece made from a magnetically permeable material positioned within the inner housing, and a coil of conductive wire circumferentially surrounding the pole piece so as to be positioned radially between the inner and outer housings. When electricity is applied to the coil, this creates a magnetic attraction between the pole piece and a valve element of the inlet valve assembly, thereby moving the valve element toward the pole piece.

[0008] In an embodiment of the fuel pump, the outer housing is annular in shape and includes a flange extending inwardly toward the inner housing such that the flange provides a path for magnetic flux to pass through when electricity is applied to the coil, and a sealing annulus may be axially compressed against the flange.

[0009] In an embodiment of the fuel pump, the solenoid assembly may further include an overmold made of an electrically insulating material and filling between the coil and the outer housing. The overmold may include a central opening. An inner housing may extend into the central opening such that an annular gap is positioned radially between the inner housing and the central opening.

[0010] The sealing annulus may be a first sealing annulus, and the solenoid assembly may further include a second sealing annulus made from an elastomeric material, having an annular shape, and positioned within the annular gap so as to be radially compressed against the inner housing and the overmold.

[0011] The second sealing annulus prevents the ingress of liquid from outside the fuel pump.

[0012] The second sealing annulus may be configured to avoid exposure to fuel from within the fuel pump.

[0013] The first sealing annulus prevents liquid from outside the fuel pump from migrating into the inner housing.

[0014] The first sealing annulus may be configured to avoid exposure to fuel from within the fuel pump.

[0015] By way of example, the solenoid assembly may further include an overmold made from an electrically insulating material and filling between the coil and the outer housing, The overmold may include a central opening into which the inner housing extends such that an annular gap is positioned radially between the inner housing and the central opening.

[0016] The solenoid assembly may further include a sealing cap closing the central opening.

[0017] The sealing cap may include a sidewall positioned in the central opening with an interference fit and may further include an end wall extending radially outward from the sidewall that abuts the overmold and limits how deeply the sealing cap is inserted into the central opening.

[0018] The sealing cap may be configured to prevent exposure to fuel from within the fuel pump.

[0019] The sealing annulus may be configured to avoid exposure to fuel from within the fuel pump.

[0020] Further features and advantages of the present invention will become more clearly apparent on reading the following detailed description of preferred embodiments of the invention, given by way of non-limiting example only, and on referring to the accompanying drawings, in which:

[0021] The invention will now be further described with reference to the accompanying drawings. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of a fuel system including a fuel pump according to the present invention; [Diagram 2] FIG. 2 is a cross-sectional view of the fuel pump of FIG. [Diagram 3] FIG. 3 is an exploded isometric view of the inlet valve assembly of the fuel pump of FIGS. 1 and 2. [Figure 4]3 is an enlarged view of a portion of FIG. 2 showing the inlet valve assembly of the fuel pump in a first position. [Diagram 5] FIG. 5 is the view of FIG. 4, now showing the inlet valve assembly in a second position. [Figure 6] 4 and 5, now showing the inlet valve assembly in a third position. [Figure 7] 4-6, now showing the inlet valve assembly in a fourth position. [Figure 8] FIG. 2 is a diagram of a closure cap according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 1, in accordance with a preferred embodiment of the present invention, a fuel system 10 for an internal combustion engine 12 is shown in schematic form. The fuel system 10 generally includes a fuel tank 14 that holds a volume of fuel that is supplied to the internal combustion engine 12 for operation of the internal combustion engine 12, a plurality of fuel injectors 16 that inject fuel directly into respective combustion chambers (not shown) of the internal combustion engine 12, a low pressure fuel pump 18 that draws fuel from the fuel tank 14 and increases the pressure of the fuel for delivery to the high pressure fuel pump 20, which further increases the pressure of the fuel for delivery to the fuel injectors 16. By way of non-limiting example only, the low pressure fuel pump 18 may increase the pressure of the fuel to approximately 500 kPa or less, and the high pressure fuel pump 20 may increase the pressure of the fuel to greater than approximately 14 MPa, and in some applications even greater than approximately 35 MPa. Although four fuel injectors 16 are illustrated, it should be understood that a fewer or greater number of fuel injectors 16 may be provided.

[0024] As shown, the low pressure fuel pump 18 may be provided within the fuel tank 14, but may alternatively be provided external to the fuel tank 14. The low pressure fuel pump 18 may be an electric fuel pump as is well known to those skilled in the art. A low pressure fuel supply line 22 provides fluid communication from the low pressure fuel pump 18 to the high pressure fuel pump 20. A fuel pressure regulator 24 may be provided to maintain a substantially uniform pressure in the low pressure fuel supply line 22 by returning a portion of the fuel provided by the low pressure fuel pump 18 to the fuel tank 14 through a fuel return line 26. Although the fuel pressure regulator 24 is shown in the low pressure fuel supply line 22 external to the fuel tank 14, it should be understood that the fuel pressure regulator 24 may be located within the fuel tank 14 or may be integrated with the low pressure fuel pump 18.

[0025] 2, the high pressure fuel pump 20 includes a fuel pump housing 28 including a plunger bore 30 extending along and centered about a plunger bore axis 32. As shown, the plunger bore 30 may be defined directly by the fuel pump housing 28 by an insert combination. The high pressure fuel pump 20 also includes a pumping plunger 34 positioned within the plunger bore 30 and reciprocates within the plunger bore 30 along the plunger bore axis 32 based on an input from a rotating camshaft 36 (only shown in FIG. 1 ) of the internal combustion engine 12. A pumping chamber 38 is defined within the fuel pump housing 28, and more specifically, the pumping chamber 38 is defined by the plunger bore 30 and the pumping plunger 34. An inlet valve assembly 40 of the high pressure fuel pump 20 is received in the inlet valve bore 28a of the fuel pump housing 28 such that the inlet valve bore 28a extends along an inlet valve bore axis 28b of the high pressure fuel pump 20 to the exterior of the fuel pump housing 28. The high pressure fuel pump 20 selectively provides and prevents fluid communication between the inlet 20a of the high pressure fuel pump 20 and the pumping chamber 38 via a pump housing inlet passage 41 of the fuel pump housing 28, while an outlet valve assembly 42 is positioned in an outlet passage 43 of the fuel pump housing 28 and selectively communicates fuel from the pumping chamber 38 to the fuel injectors 16 via a fuel rail 44 with which each of the fuel injectors 16 is in fluid communication. In operation, the reciprocation of the pumping plunger 34 increases the volume of the pumping chamber 38 during the intake stroke (downward when oriented in FIG. 2 ) of the pumping plunger 34 when the plunger return spring 46 moves the pumping plunger 34 downward, and conversely reduces the volume of the pumping chamber 38 during the compression stroke (upward when oriented in FIG. 2 ) when the camshaft 36 moves the pumping plunger 34 upward against the force of the plunger return spring 46. In this manner, fuel is selectively drawn into the pumping chamber 38 during the intake stroke depending upon the operation of the inlet valve assembly 40, as will be explained in more detail below, and conversely, fuel is compressed within the pumping chamber 38 by the pumping plunger 34 during the compression stroke and discharged under pressure through the outlet valve assembly 42 to the fuel rail 44 and fuel injectors 16.For clarity, the pumping plunger 34 is shown in solid lines in Figure 2 to represent the intake stroke, and the pumping plunger 34 is shown in dashed lines in Figure 2 to represent the compression stroke. The high pressure fuel pump 20 also includes a pressure relief valve assembly 48 disposed downstream of the outlet valve assembly 42 to provide a flow path back to the pumping chamber 38 in the event that pressure downstream of the outlet valve assembly 42 reaches a predetermined limit that could result in an unsafe operating condition if not relieved.

[0026] The outlet valve assembly 42 generally comprises an outlet valve member 42a, an outlet valve seat 42b, and an outlet valve spring 42c. The outlet valve member 42a, shown by way of non-limiting example only as a ball, is biased towards the outlet valve seat 42b by the outlet valve spring 42c, which is selected to cause the outlet valve member 42a to open when a predetermined pressure differential between the pumping chamber 38 and the fuel rail 44 is reached. The outlet valve assembly 42 is oriented such that fuel is permitted to flow out of the pumping chamber 38 through the outlet valve assembly 42, but is not permitted to flow into the pumping chamber 38 through the outlet valve assembly 42.

[0027] The pressure relief valve assembly 48 generally comprises a pressure relief valve member 48a, a pressure relief valve seat 48b, and a pressure relief valve spring 48c. The pressure relief valve member 48a, shown by way of non-limiting example only as a ball, is biased towards the pressure relief valve seat 48b by the pressure relief valve spring 48c, which is selected to cause the pressure relief valve member 48a to open when a predetermined pressure differential between the pumping chamber 38 and the fuel rail 44 is reached. The pressure relief valve assembly 48 is oriented such that fuel is permitted to flow through the pressure relief valve assembly 48 into the pumping chamber 38, but is not permitted to flow through the pressure relief valve assembly 48 out of the pumping chamber 38.

[0028] The inlet valve assembly 40 will now be described with particular reference to Figures 3-7. The inlet valve assembly 40 comprises a valve body 50, a valve spool 52 positioned within the valve body 50, a check valve 54, and a solenoid assembly 55. The various elements of the inlet valve assembly 40 will be described in more detail in the paragraphs that follow.

[0029] The disc 50 extends along an inlet bore axis 28b from a first disc end 50a to a second disc end 50b. A disc bore 58 extends from the first disc end 50a into the disc 50 and terminates at a disc end wall 60 which extends to the second disc end 50b such that the disc bore 58 is preferably cylindrical. A disc first inlet passage 62 extends from a disc outer periphery 50c of the disc 50 and extends through the disc 50 to open into the disc bore 58. A disc second inlet passage 64 (not visible in FIG. 3 but visible in FIGS. 4-7) extends from the disc outer periphery 50c and extends through the disc 50 to open into the disc bore 58. As shown, the disc first inlet passage 62 and the disc second inlet passage 64 are axially spaced apart from one another along the inlet bore axis 28b such that the disc second inlet passage 64 is axially located between the disc first end 50a and the disc first inlet passage 62. As also shown, multiple disc first inlet passages 62 may be provided such that each disc first inlet passage 62 is located at the same axial location along the inlet bore axis 28b but is spaced apart from the other disc first inlet passages 62 about the disc outer periphery 50c. Although only one disc second inlet passage 64 is shown, it should be understood that multiple disc second inlet passages 64 may be provided at the same axial location along the inlet bore axis 28b but spaced apart from one another about the disc outer periphery 50c.

[0030] A disc central passage 66 extends through the disc end wall 60 connecting the disc second end 50b with the disc bore 58 and centered along the inlet bore axis 28b. A plurality of disc outlet passages 68 are provided in the disc end wall 60 such that each disc outlet passage 68 extends through the disc end wall 60 and connects the disc second end 50b with the disc bore 58. Each disc outlet passage 68 is laterally offset from the disc central passage 66 and extends through the disc end wall 60 in a direction parallel to the inlet bore axis 28b.

[0031] As shown, the disk outer perimeter 50c may include three sections of different diameters: a disk outer perimeter first portion 50d of the disk outer perimeter 50c begins at the disk first end 50a and extends to a disk outer perimeter second portion 50e of the disk outer perimeter 50c such that the disk outer perimeter first portion 50d is smaller in diameter than the disk outer perimeter second portion 50e. As shown, the first portion 50d of the disc outer periphery may be positioned entirely outside the pump housing inlet passage 41, and the second portion 50e of the disc outer periphery includes the first disc inlet passage 62 and the second disc inlet passage 64 such that the first disc inlet passage 62 and the second disc inlet passage 64 are always in fluid communication with a portion of the pump housing inlet passage 41 that is upstream of the inlet valve assembly 40, i.e., the first disc inlet passage 62 and the second disc inlet passage 64 are always in fluid communication with a portion of the pump housing inlet passage 41 that is between the inlet valve assembly 40 and the low pressure fuel pump 18. The third portion 50f of the disc outer periphery 50c extends from the second disc outer periphery portion 50e to the second disc end 50b such that the third portion 50f of the disc outer periphery 50c is of larger diameter than the second disc outer periphery portion 50e. The third portion 50f of the valve body outer periphery is sealingly engaged with the pump housing inlet passage 41 such that fluid communication through the pump housing inlet passage 41 beyond the inlet valve assembly 40 at the interface between the pump housing inlet passage 41 and the third portion 50f of the valve body outer periphery is prevented and fluid communication through the pump housing inlet passage 41 beyond the inlet valve assembly 40 is only possible through the valve body hole 58.

[0032] The valve spool 52 is made of a magnetic material and extends along and about the inlet valve bore axis 28b from a valve spool first end 52a to a valve spool second end 52b. The valve spool 52 includes a valve spool first portion 52c proximate the valve spool first end 52a and a valve spool second portion 52d proximate the valve spool second end 52b. The valve spool first portion 52c has a valve spool outer periphery 52e complementary to the disc bore 58 such that the valve spool outer periphery 52e and the disc bore 58 are sized to substantially prevent fuel from passing between an interface between the valve spool outer periphery 52e and the disc bore 58. As used herein, substantially preventing fuel from passing between the interface of the valve spool outer periphery 52e and the disc bore 58 encompasses allowing a small amount of fuel to pass between the interface that still allows operation of the high pressure fuel pump 20 as would be readily appreciated by one skilled in the art. The second portion 52d of the valve spool includes a base portion 52f extending from the first portion 52c of the valve spool such that the base portion 52f is smaller in diameter than the first portion 52c of the valve spool, thereby providing an annular space radially between the base portion 52f and the disc bore 58. The second portion 52d of the valve spool also includes a tip portion 52g extending from the base portion 52f and terminating at the second end 52b of the valve spool. The tip portion 52g is smaller in diameter than the base portion 52f, thereby defining a valve spool shoulder 52h where the tip portion 52g meets the base portion 52f. The tip portion 52g is sized to be positioned within the disc central passage 66 of the disc 50 such that it can freely slide within the disc central passage 66 at the inlet bore axis 28b. In use, the tip portion 52g is used to mate with the check valve 54, as will be described in more detail below.

[0033] The valve spool first portion 52c is provided with a valve spool groove 70 extending radially inwardly from the valve spool outer periphery 52e so as to be annular in shape. The valve spool groove 70 is selectively aligned or unaligned with the disc first inlet passage 62 and the disc second inlet passage 64 to control fluid communication through the pump housing inlet passage 41, as will be described in more detail below. One or more valve spool passages 72 are provided extending from the valve spool groove 70 through the valve spool first portion 52c toward the valve spool second end 52b, thereby providing fluid communication between the valve spool groove 70 and the disc outlet passage 68.

[0034] A valve spool end bore 74 extends from the valve spool first end 52a into the valve spool 52. As shown, the valve spool end bore 74 may comprise a valve spool end bore first portion 74a that is internally frusto-conical and a valve spool end bore second portion 74b that is cylindrical and terminates at a valve spool end bore bottom 74c. A valve spool connection passage 76 provides fluid communication between the valve spool groove 70 and the valve spool end bore 74, as may be formed by a pair of orthogonal bores as shown, by way of non-limiting example only.

[0035] The check valve 54 includes a check valve member 78 and a travel limiter 80. The check valve 54 is disposed on the second end 52b of the valve spool such that the check valve member 78 can be moved between a seated position (shown in FIGS. 5-7) in which the check valve member 78 blocks the valve disc outlet passage 68 and an open position (shown in FIG. 4) in which the check valve member 78 does not block the valve disc outlet passage 68, as will be described in more detail below. It should be noted that the check valve member 78 includes a check valve center portion 78a which is a flat plate having check valve passages 78b extending therethrough, and only select check valve passages 78b are labeled in FIG. 3 for clarity. The check valve passages 78b are disposed through the check valve center portion 78a such that they are not axially aligned with the valve disc outlet passages 68. A plurality of check valve legs 78c extend from the check valve center portion 78a in a resiliently flexible manner. The free end of the check valve leg 78c is fixed, for example, by welding, to the second end 50b of the valve body. As a result, when the pressure difference between the valve body bore 58 and the pumping chamber 38 is sufficiently high, the check valve central portion 78a is unseated from the valve spool 52 due to the elastic deformation of the check valve leg 78c, thereby opening the valve body outlet passage 68. The travel limiting portion 80 includes a travel limiting annulus 80a that is axially spaced from the second end 50b of the valve body to provide an allowable amount of displacement of the check valve member 78. The travel limiting portion 80 also includes a plurality of travel limiting legs 80b that provide axial spacing between the travel limiting annulus 80a and the second end 50b of the valve body. The travel limiting legs 80b are integrally formed with the travel limiting annulus 80a and fixed, for example, by welding, to the second end 50b of the valve body.

[0036] Solenoid assembly 55 comprises an inner housing 82, a pole piece 84 positioned within inner housing 82, a return spring 86, a spool 88, a coil 90, a flux washer 91, an overmold 92, and an outer housing 94. The various elements of solenoid assembly 55 are described in more detail in the paragraphs that follow.

[0037] The inner housing 82 is hollow and extends along and about the inlet valve bore axis 28b such that the inner housing first portion 82a is open and has a larger diameter than the inner housing second portion 82b, which is closed by the inner housing end wall 82c. The inner housing first portion 82a is received within the inlet valve bore 28a so as to be sealed to the fuel pump housing 28 to prevent leakage of fuel from the pump housing inlet passage 41 to the exterior of the fuel pump housing 28. This sealing may be accomplished by one or more of an interference fit between the inner housing first portion 82a and the inlet valve bore 28a, a weld around an inner corner where the inner housing first portion 82a faces the fuel pump housing 28, and an adhesive, by way of non-limiting example only. An annular gap is provided between the inner periphery of the inner housing first portion 82a and the disk outer periphery second portion 50e to provide fluid communication between the pump housing inlet passage 41 and the disk second inlet passage 64. The inner periphery of the inner housing second portion 82b mates with the disk outer periphery first portion 50d to prevent fuel communication between the interface of the inner periphery of the inner housing second portion 82b and the disk outer periphery first portion 50d.

[0038] The pole piece 84 is made of a magnetically permeable material and is received in the inner housing second portion 82b so as to extend along and about the inlet valve bore axis 28b. The pole piece first end 84a is frustoconical such that the angle of the pole piece first end 84a is complementary to the angle of the valve spool end bore first portion 74a. In this manner, the pole piece first end 84a is received in the valve spool end bore first portion 74a. The pole piece second end 84b, opposite the pole piece first end 84a, is located in the closed end of the inner housing 82. The pole piece bore 84c extends axially through the pole piece 84 from the pole piece first end 84a to the pole piece second end 84b such that a larger diameter portion of the pole piece bore 84c extends from the pole piece first end 84a into the pole piece 84, thereby defining a pole piece shoulder 84d facing the valve spool end bore bottom 74c. The return spring 86 is partially received by the pole piece bore 84c so as to abut against the pole piece shoulder 84d. The return spring 86 is also partially received within the valve spool end bore second portion 74b and abuts against the valve spool end bore bottom 74c. The return spring 86 is held in compression between the pole piece shoulder 84d and the valve spool end bore bottom 74c such that the return spring 86 biases the valve spool 52 away from the pole piece 84.

[0039] The spool 88 is made of an electrically insulating material, such as plastic, and is centered about and extends along the inlet valve bore axis 28b such that the spool 88 circumferentially surrounds the inner housing second portion 82b in a closely fitted relationship. The coil 90 is a winding of conductive wire wound around the outer periphery of the spool 88 such that it circumferentially surrounds the pole pieces 84. As a result, when the coil 90 is energized with electrical current, the valve spool 52 is magnetically attracted to and moved toward the pole pieces 84, and when the coil 90 is not energized with electrical current, the valve spool 52 is moved away from the pole pieces 84 by the return spring 86. A more detailed description of operation is provided below.

[0040] The outer housing 94 circumferentially surrounds the inner housing 82, the spool 88, and the coil 90 such that the spool 88 and the coil 90 are positioned radially between the inner housing 82 and the outer housing 94. An annular chamber 96 is formed radially between the first part 82a of the inner housing and the outer housing 94 such that the annular chamber 96 is positioned axially between the exterior of the fuel pump housing 28 and a flange 94a of the outer housing 94, which is annular in shape and extends inwardly toward the second part 82b of the inner housing. The flange 94a provides a path for magnetic flux to pass when a current is applied to the coil 90, and as a result, a very small radial spacing is provided radially between the inner housing 82 and the flange 94a. A first sealing annulus 98 is positioned within the annular chamber 96 and is compressed axially between the fuel pump housing 28 and the flange 94a by the fuel pump housing 28 and the flange 94a. The first sealing ring 98 is made from an elastomeric material, the specific composition of which is selected based on environmental factors such as temperature and liquids that may come into contact with the first sealing ring 98, as will be readily appreciated by those skilled in the art. The first sealing ring 98 prevents liquids from the outside environment from migrating into the inner housing 82, where liquids may otherwise collect and become difficult to dry, which may cause degradation to the inner housing 82, particularly in the small radial gap between the inner housing 82 and the flange 94a of the outer housing 94, where crevice corrosion and erosion may occur if liquids are allowed to accumulate. It is important to note that the first sealing ring 98 does not play any role in sealing the fuel in the high pressure fuel pump 20, i.e., the first sealing ring 98 is not exposed to the fuel in the high pressure fuel pump 20, but is provided to prevent the ingress of liquids present in the environment outside the high pressure fuel pump 20. In addition to its primary purpose of preventing the ingress of liquids present in the environment external to the high pressure fuel pump 20, the first sealing annulus 98 may also provide suppression of vibrations and audible noises produced from the operation of the high pressure fuel pump 20 during operation that may otherwise be transmitted to the environment.

[0041] Flux washer 91 is positioned within outer housing 94 such that the outer periphery of flux washer 91 engages the inner periphery of outer housing 94 and such that spool 88 and coil 90 are axially positioned between flange 94a and flux washer 91. Flux washer 91 provides a path for magnetic flux to pass when current is applied to coil 90, resulting in a very small radial spacing being provided radially between inner housing 82 and flux washer 91.

[0042] The overmold 92 is an electrically insulating material, such as plastic, that fills the void between the spool 88 / coil 90 and the outer housing 94 such that the overmold 92 extends axially from the outer housing 94 to define an electrical connector 100 that includes terminals (not shown) that are coupled to opposite ends of the coil 90. The electrical connector 100 is configured to mate with a complementary electrical connector (not shown) to provide electrical current to the coil 90 during use. The overmold 92 includes a central opening 92a that extends along the inlet valve bore axis 28b to the flux washer 91. The inner housing 82 extends into the central opening 92a such that an annular gap 102 is formed radially between the overmold 92 and the inner housing 82. A second sealing annulus 104 is positioned in the annular gap 102 and is compressed by the overmold 92 and the inner housing 82 radially between the overmold 92 and the inner housing 82. The second sealing ring 104 is made from an elastomeric material, the specific composition of which is selected based on environmental factors such as temperature and liquids that may come into contact with the second sealing ring 104, as would be readily recognized by one skilled in the art. Unlike the first sealing ring 98, which is circular in cross-sectional shape prior to installation, the second sealing ring 104 may be elongated in a direction parallel to the inlet valve hole axis 28b prior to installation to provide structural integrity to the second sealing ring 104 since it is not captured in that direction. This cross-sectional shape also prevents the second sealing ring 104 from rolling during installation in the annular gap 102. The second sealing ring 104 prevents liquid from the outside environment from migrating into the small radial gap between the inner housing 82 and the flux washer 91, where liquid may otherwise collect and be difficult to dry, and where crevice corrosion and erosion may occur if liquid is allowed to accumulate. It is important to note that the second sealing annulus 104 plays no role in sealing the fuel within the high pressure fuel pump 20, i.e., the second sealing annulus 104 is not exposed to the fuel within the high pressure fuel pump 20, but rather is provided to prevent the ingress of liquids present in the environment external to the high pressure fuel pump 20.In addition to its primary purpose of preventing the ingress of liquids present in the environment external to the high pressure fuel pump 20, the second sealing annulus 104 can also provide suppression of vibrations and audible noises produced from the operation of the high pressure fuel pump 20 during operation that may otherwise be transmitted to the environment.

[0043] The operation of the high pressure fuel pump 20, and specifically the inlet valve assembly 40, will now be described with particular reference to Figure 4, which shows the valve spool 52 in a first position resulting from the absence of current supplied to the coil 90 of the solenoid assembly 55. When current is not supplied to the coil 90, the return spring 86 urges the valve spool 52 away from the pole piece 84 until the valve spool shoulder 52h abuts the disc end wall 60, thereby causing the tip portion 52g of the valve spool 52 to project beyond the disc second end 50b to hold the check valve member 78 in an unseated position permitting flow through the disc outlet passage 68, and such that the fluid outlet passage 68 is in fluid communication with the pumping chamber 38. It should be noted that even in the first position, the valve spool groove 70 is aligned with the disc first inlet passage 62, but the valve spool groove 70 is not aligned with the disc second inlet passage 64. In this manner, the valve spool 52 maintains the check valve member 78 in the unseat position and the disc first inlet passage 62 is in fluid communication with the disc outlet passage 68. It should be noted that in the first position, the alignment between the valve spool groove 70 and the disc first inlet passage 62 provides a path to the pump housing inlet passage 41. In this manner, the first position is a default position that provides a limp-home operation of the high pressure fuel pump 20, i.e., in the event that power to the solenoid assembly 55 is unintentionally removed, the check valve member 78 is held in the unseat position by the valve spool 52 to prevent pressurization of fuel by the pumping plunger 34, so that fuel is not pressurized by the high pressure fuel pump 20, but a sufficient amount and pressure of fuel is provided by the low pressure fuel pump 18 to the fuel injectors 16 for continued operation of the internal combustion engine 12. It should be noted that the routing to the pump housing inlet passage 41 that allows for limp-home operation of the high pressure fuel pump 20 also allows for the use of only one pressure relief valve, namely the pressure relief valve assembly 48 .

[0044] 5, the valve spool 52 is shown in a second position resulting from current being supplied to the coil 90 of the solenoid assembly 55 at a first duty cycle. When current is supplied to the coil 90 at the first duty cycle, the valve spool 52 is attracted to the pole piece 84, thereby moving the valve spool 52 toward the pole piece 84 and compressing the return spring 86 to a greater degree than in the first position. The valve spool connecting passage 76 may displace fuel located between the valve spool 52 and the pole piece 84 toward the disc outlet passage 68 during movement of the valve spool 52 toward the pole piece 84, and may also equalize pressure at each axial end of the valve spool 52. In the second position, the tip portion 52g is positioned so that it no longer protrudes beyond the disc second end 50b, and as a result, the check valve member 78 is moved to a seated position preventing flow through the disc outlet passage 68 to the disc bore 58. Also, in the second position, the valve spool groove 70 is not aligned with the disc first inlet passage 62 and is not aligned with the disc second inlet passage 64, thus preventing fuel from entering or exiting the disc bore 58 through the disc first inlet passage 62 and the disc second inlet passage 64. As a result, the disc first inlet passage 62 and the disc second inlet passage 64 are not in fluid communication with the disc outlet passage 68. The second position of the valve spool 52 is used when the internal combustion engine 12 is running but does not require fuel to be delivered from the fuel injector 16, which may occur during a deceleration cutoff event when the vehicle is coasting and no fuel is required. In this manner, the second position prevents fuel from being delivered to the fuel injector 16.

[0045] 6, the valve spool 52 is shown in a third position resulting from current being supplied to the coil 90 of the solenoid assembly 55 at a second duty cycle that is greater than the first duty cycle used to achieve the second position of the valve spool 52. When current is supplied to the coil 90 at the second duty cycle, the valve spool 52 is attracted to the pole piece 84, thereby moving the valve spool 52 toward the pole piece 84 and compressing the return spring 86 to a greater degree than in the second position. As in the second position, the third position results in the tip portion 52g being positioned so that it no longer protrudes beyond the disc second end 50b, and as a result, the check valve member 78 is moved to a seated position preventing flow through the disc outlet passage 68 to the disc bore 58. It should be noted, however, that when the pressure differential between the disc bore 58 and the pumping chamber 38 is high enough, i.e., during the intake stroke, the check valve member 78 can move to the unseat position. Also, in the third position, the valve spool groove 70 is not aligned with the disc first inlet passage 62, but now the valve spool groove 70 is aligned with the disc second inlet passage 64, and thus fuel is provided to the disc bore 58 through the disc second inlet passage 64. As a result, during the intake stroke of the pumping plunger 34, a pressure differential is created that causes fuel to flow through the disc second inlet passage 64 and through the inlet valve assembly 40, thereby moving the check valve member 78 to the unseat position that allows fuel to flow into the pumping chamber 38. During the compression stroke of the pumping plunger 34, pressure increases in the pumping chamber 38, thereby moving the check valve member 78 to a seated position, which prevents fuel from flowing from the pumping chamber 38 to the valve body bore 58 and allows the pressurized fuel in the pumping chamber 38 to be discharged through the outlet valve assembly 42. The third position of the valve spool 52 is used when the internal combustion engine 12 is required to produce light output torque, since it is noted that the alignment of the valve spool groove 70 and the valve body second inlet passage 64 provides restricted passage, thereby providing a small amount of fuel to the pumping chamber 38 during the intake stroke of the pumping plunger 34 to assist in fueling the internal combustion engine 12 at light loads.

[0046] 7, the valve spool 52 is shown in a fourth position resulting from current being supplied to the coil 90 of the solenoid assembly 55 at a third duty cycle that is greater than the second duty cycle used to achieve the third position of the valve spool 52. When current is supplied to the coil 90 at the third duty cycle, the valve spool 52 is attracted to the pole piece 84, thereby moving the valve spool 52 toward the pole piece 84 and compressing the return spring 86 to a greater degree than in the third position. As in the second and third positions, the fourth position results in the tip portion 52g being positioned so that it no longer protrudes beyond the disc second end 50b, and as a result, the check valve member 78 is moved to a seated position preventing flow through the disc outlet passage 68 to the disc bore 58. It should be noted, however, that when the pressure differential between the disc bore 58 and the pumping chamber 38 is high enough, i.e., during the intake stroke, the check valve member 78 can move to the unseat position. Also, in the fourth position, the valve spool groove 70 is not aligned with the disc first inlet passage 62 as in the third position, but now the valve spool groove 70 is aligned with the disc second inlet passage 64, and thus fuel is provided to the disc bore 58 through the disc second inlet passage 64. As a result, during the intake stroke of the pumping plunger 34, a pressure differential is created that causes fuel to flow through the disc second inlet passage 64 and through the inlet valve assembly 40, thereby moving the check valve member 78 to the unseat position that allows fuel to flow into the pumping chamber 38. During the compression stroke of the pumping plunger 34, pressure increases in the pumping chamber 38, thereby moving the check valve member 78 to a seated position which prevents fuel from flowing from the pumping chamber 38 into the disc bore 58 and allows the pressurized fuel in the pumping chamber 38 to be discharged through the outlet valve assembly 42. As will now become apparent, the third and fourth positions of the valve spool 52 are nearly identical, except that the fourth position differs from the third position in that the alignment of the valve spool groove 70 and the disc second inlet passage 64 is less restrictive than in the third position.As a result, the fourth position of the valve spool 52 is used when the internal combustion engine 12 is required to produce a higher output torque because the alignment of the valve spool groove 70 and the valve disc second inlet passage 64 provides a less restricted passage, thereby providing a greater amount of fuel to the pumping chamber 38 during the intake stroke of the pumping plunger 34, as compared to the third position, to assist in fueling the internal combustion engine 12 at high loads.

[0047] As will now become apparent, different duty cycles can be provided to vary the amount of fuel delivered to the pumping chamber 38, which results in varying degrees of alignment of the valve spool groove 70 with the valve disc second inlet passage 64, thereby varying the degree of restriction. In other words, the third and fourth positions as described above are merely example positions of the valve spool 52, and other duty cycles may be provided to provide different amounts of fuel to the pumping chamber 38 to achieve different output torques of the internal combustion engine 12. An electronic control unit 106 is used to provide current to the coil 90 at the various duty cycles described herein. The electronic control unit 106 can receive input from a pressure sensor 108 that senses pressure in the fuel rail 44 to provide an appropriate duty cycle to the coil 90 to maintain a desired pressure in the fuel rail 44, which can vary based on the commanded torque desired to be generated by the internal combustion engine 12.

[0048] Although the inner housing 82 is shown and described herein as directly engaging and directly welded to the fuel pump housing 28, it should be understood that an intermediate element, such as a sleeve (not shown), may be provided radially between the inner housing 82 and the fuel pump housing 28, and this intermediate element is to be considered within the scope of this disclosure to the fuel pump housing 28.

[0049] In addition to or as an alternative to the second sealing annulus 104, a sealing cap 110 may be provided as shown in FIG. 8 that closes an open end of the central opening 92a opposite the flux washer 91. The sealing cap 110 may be annular in shape and include a sidewall 110a that fits into the central opening 92a with an interference fit, such as with one or more annular ribs 110b that circumferentially surround the sidewall 110a to retain the sealing cap 110 to the overmold 92 and to prevent the ingress of liquids. The sealing cap 110 may also include an end wall 110c that closes one open end of the sidewall 110a, such that the end wall 110c extends radially outward from the sidewall 110a, thereby forming a stop that limits the extent to which the sealing cap 110 can be inserted into the central opening 92a. The sealing cap 110 is made from an elastomeric material, the specific composition of which is selected based on environmental factors such as temperature and liquids that may come into contact with the first sealing annulus 98, as will be readily appreciated by those skilled in the art. The sealing cap 110 prevents liquid from entering the central opening 92a, thereby preventing liquid from migrating to areas where it may cause degradation, as described above with respect to the second sealing annulus 104. It is important to note that the sealing cap 110 plays no role in sealing the fuel within the high pressure fuel pump 20, i.e., the sealing cap 110 is not exposed to the fuel within the high pressure fuel pump 20, but is provided to prevent the ingress of liquids present in the environment external to the high pressure fuel pump 20. In addition to its primary purpose of preventing the ingress of liquids present in the environment external to the high pressure fuel pump 20, the sealing cap 110 can also provide suppression of vibrations and audible noises created from the operation of the high pressure fuel pump 20 during operation that may otherwise be transmitted to the environment.

[0050] The high pressure fuel pump 20 as described herein with one or more of the first sealing annulus 98, the second sealing annulus 104, and the sealing cap 110 minimizes the possibility of liquid from the outside environment reaching elements of the inlet valve assembly 40 and the solenoid assembly 55 which, if reached, could result in undesirable operation of the inlet valve assembly 40 or the solenoid assembly 55. Additionally, vibrations and audible noises produced from operation of the high pressure fuel pump 20 may be suppressed.

[0051] While the present invention has been described in terms of its preferred embodiments, it is not intended to be so limited, but rather to be limited in scope only as set forth in the claims which follow. [Explanation of symbols]

[0052] 10 Fuel System 12 Internal Combustion Engine 14 Fuel Tank 16 fuel injector 18 Low pressure fuel pump 20 High pressure fuel pump 20a entrance 22 Low pressure fuel supply line 24 Fuel pressure regulator 26 Fuel return passage 28 Fuel Pump Housing 28a Inlet valve hole 28b Inlet valve hole shaft 30 Plunger Hole 32 Plunger hole shaft 34 Pumping Plunger 36 Camshaft 38 Pumping Room 40 Inlet valve assembly 41 Pump housing inlet passage 42 Outlet valve assembly 42a Outlet valve member 42b Outlet valve seat 42c Outlet valve spring 43 Exit path 44 Fuel Rail 46 Plunger return spring 48 Pressure relief valve assembly 48a Pressure relief valve member 48b Pressure relief valve seat 48c Pressure relief valve spring 50 Valve body 50a: first end of valve body 50b second end of valve body 50c Outside of valve body 50d: a first portion around the outside of the valve body 50e A second portion around the outside of the valve body 50f: The third part around the outside of the valve body 52 Valve spool 52a: first end of valve spool 52b second end of valve spool 52c first portion of valve spool 52d Second part of valve spool 52e Valve spool outer periphery 52f Foundation part 52g tip 52h Valve spool shoulder 54 Check valve 55 Solenoid Assembly 58 Valve hole 60 Valve end wall 62 first inlet passage of valve body 64 Second inlet passage of valve body 66 Valve body central passage 68 Valve outlet passage 70 Valve spool groove 72 Valve spool path 74 Valve spool end hole 74a first portion of valve spool end hole 74b second portion of valve spool end hole 74c Valve spool end hole bottom 76 Valve spool connection path 78 Check valve member 78a Check valve center part 78b Check valve passage 78c Check valve leg 80 Progress Restriction Section 80a Progression restriction ring 80b Progression restriction leg 82 Inner housing 82a: First portion of inner housing 82b Second part of the inner housing 82c Inner housing end wall 84 pole piece 84a First end of pole piece 84b Second end of pole piece 84c Pole hole 84d Pole shoulder 86 Return spring 88 Spool 90 Coil 91 Flux washer 92 Overmolding 92a Center opening 94 Outer housing 94a flange 96 Circular Room 98 First sealing ring 100 Electrical Connector 102 Annular gap 104 Second sealing ring 106 Electronic Control Unit 108 Pressure Sensor 110 Sealing cap 110a side wall 110b Rib 110c end wall

Claims

1. A fuel pump (20), a fuel pump housing (28) having a pumping chamber (38) defined therein and an inlet valve bore (28a) extending to an exterior of the fuel pump housing (28) along an inlet valve bore axis (28b); a pumping plunger (34) that reciprocates within the plunger bore such that a suction stroke of the pumping plunger (34) increases the volume of the pumping chamber (38) and a compression stroke of the pumping plunger (34) decreases the volume of the pumping chamber (38); an inlet valve assembly (40) for: 1) selectively providing fluid communication between an inlet (20a) of the fuel pump (20) and the pumping chamber (38); and 2) selectively preventing fluid communication between the inlet (20a) of the fuel pump (20) and the pumping chamber (38), said inlet valve assembly (40) being configured to: an inner housing (82) received within the inlet valve hole (28a) such that the inner housing (82) extends to an exterior of the fuel pump housing (28) and such that an outer periphery of the inner housing (82) is sealed to an inner periphery of the inlet valve hole (28a) to prevent fuel from passing radially between the inner housing (82) and the inlet valve hole (28a) to an exterior of the fuel pump housing (28); an outer housing (94) positioned outside the fuel pump housing (28) and circumferentially surrounding the inner housing (82), wherein an annular chamber (96) is defined between the inner housing (82) and the outer housing (94) in a radial direction and between the outer housing (94) and the fuel pump housing (28) in an axial direction; and a sealing annulus (98) made of an elastomeric material, having an annular shape, and positioned within the annular chamber (96) so as to be axially compressed relative to the fuel pump housing (28) and the outer housing (94); an inlet valve assembly (40) comprising: A fuel pump (20).

2. The inlet valve assembly (40) includes a solenoid assembly (55), the solenoid assembly comprising: The inner housing (82); The outer housing (94); a pole piece (84) made of a magnetically permeable material positioned within the inner housing (82); The fuel pump (20) of claim 1, comprising:

3. 3. The fuel pump of claim 2, wherein the solenoid assembly further comprises a coil of conductive wire circumferentially surrounding the pole piece so as to be positioned radially between the inner housing and the outer housing, wherein electricity applied to the coil creates a magnetic attraction between the pole piece and a valve element of the inlet valve assembly, thereby moving the valve element toward the pole piece.

4. the outer housing (94) is annular in shape and includes a flange (94a) extending inwardly toward the inner housing (82), such that when electricity is applied to the coil (90), the flange (94a) provides a path for magnetic flux to pass; The fuel pump (20) of claim 3, wherein the sealing annulus (98) is axially compressed against the flange.

5. 5. The fuel pump (20) of claim 3 or 4, wherein the solenoid assembly (55) further comprises an overmold (92) made from an electrically insulating material and filling between the coil (90) and the outer housing (94), the overmold (92) including a central opening (92a).

6. 6. The fuel pump of claim 5, wherein the inner housing extends into the central opening such that an annular gap is positioned radially between the inner housing and the central opening.

7. the sealing ring is a first sealing ring (98); 7. The fuel pump (20) of claim 6, wherein the solenoid assembly (55) further comprises a second sealing annulus (104) made from an elastomeric material, annular in shape, and positioned within the annular gap (102) so as to be radially compressed against the inner housing (82) and the overmold (92).

8. The fuel pump (20) of claim 7, wherein the second sealing annulus (104) prevents ingress of liquid from outside the fuel pump (20).

9. The fuel pump (20) of claim 7 or 8, wherein the second sealing annulus (104) is configured to avoid exposure to fuel from within the fuel pump (20).

10. 10. The fuel pump (20) of claim 7, wherein the first sealing annulus (98) prevents liquid from outside the fuel pump (20) from migrating into the inner housing (82).

11. The fuel pump (20) of claim 9 or 10, wherein the first sealing annulus (98) is configured to avoid exposure to fuel from within the fuel pump (20).

12. The fuel pump (20) of any one of claims 5 to 11, wherein the solenoid assembly further comprises a sealing cap (110) closing the central opening (92a).

13. The sealing cap (110) a side wall (110a) positioned within said central opening (92a) with an interference fit; an end wall (110c) extending radially outward from the side wall (110a) that abuts the overmold and limits how deeply the sealing cap (110) can be inserted into the central opening (92a); The fuel pump (20) of claim 12, comprising:

14. The fuel pump (20) of claim 13, wherein the sealing cap (110) is configured to prevent exposure to fuel from within the fuel pump.

Images