Fuel pump with inlet valve assembly

Abstract

A 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 a plunger bore such that an intake stroke of the pumping plunger (34) increases a 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) 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 pump housing (28). A seal ring (98) is located within the annular chamber (96) such that the seal ring (98) is axially compressed against the pump housing (28) and the outer housing (94).

Description

Technical Field

[0001] The present invention relates to a fuel pump for supplying fuel to an internal combustion engine, more specifically, to such a fuel pump including an inlet valve assembly, and even more specifically to such a fuel pump having an inlet valve assembly that is robust to exposure to external ambient fluids. Background Technology

[0002] Fuel systems in modern internal combustion engines that use gasoline as fuel, particularly those used in the automotive market, employ gasoline direct injection (GDi), which provides fuel injectors that inject fuel directly into the combustion chamber of the internal combustion engine. In such GDi systems, fuel from the fuel tank is supplied at a relatively low pressure by a low-pressure fuel pump, typically an electric fuel pump located within the fuel tank. The low-pressure fuel pump supplies fuel to a high-pressure fuel pump, which typically includes a fuel pump housing and a pumping plunger that reciprocates within the fuel pump housing via the engine's camshaft. The reciprocating motion of the pumping plunger also pressurizes the fuel to supply it to the fuel injectors, which inject the fuel directly into the combustion chamber of the internal combustion engine. During operation, the internal combustion engine is affected by varying demands on output torque. To accommodate these varying output torque demands, the quality of fuel delivered by the pumping plunger in each stroke must also be changed. One strategy for altering fuel delivery via the high-pressure fuel pump is to use an inlet valve assembly that includes a solenoid valve. The inlet valve assembly allows fuel to fill the pumping chamber during each intake stroke; however, a solenoid can be operated to keep the inlet valve assembly open during a portion of the pump plunger's compression stroke, allowing some fuel to overflow toward the source. When the solenoid is then operated to allow the inlet valve assembly to close, the remainder of the compression stroke pressurizes the fuel and discharges it to the fuel injector. The inlet valve assembly is known to be received within an orifice in the fuel pump housing and extends to the outside of the fuel pump housing. To prevent fuel leakage, a sealing device is provided to seal between the fuel pump housing and the inlet valve assembly. In some arrangements, such as the one provided in U.S. Patent No. 10,947,942 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 arrangements, such as the one provided in U.S. Patent No. 7,401,594 to Usui et al., the inlet valve assembly can be sealed to the fuel pump housing by radially distributing an O-ring between the inlet valve assembly and the fuel pump housing. In each case, the sealing device is configured to prevent fuel from leaving the fuel pump housing between the inlet valve assembly and the fuel pump housing. However, the portion of the inlet valve assembly extending outside the fuel pump housing may be exposed to environmental conditions that could cause liquids such as rainwater or brine from de-icing roads to deposit on the outlet control valve. These liquids may seep into the interfaces of the components forming the inlet control valve or solenoid and, over time, may damage one or more of the components of the inlet control valve or solenoid, potentially leading to undesirable operation of the inlet control valve.

[0003] What is needed is a fuel pump that minimizes or eliminates one or more of the disadvantages described above. Summary of the Invention

[0004] According to one aspect of the invention, a fuel pump includes: a fuel pump housing having a pumping chamber defined therein and an inlet valve port extending along an axis to the outside of the fuel pump housing; a pumping plunger reciprocating within a plunger port such that an intake stroke of the pumping plunger increases the volume of the pumping chamber and a compression stroke of the pumping plunger decreases the volume of the pumping chamber; and an inlet valve assembly having the following features: 1) selectively providing fluid communication between the inlet of the fuel pump and the pumping chamber; and 2) selectively preventing fluid communication between the inlet of the fuel pump and the pumping chamber. The inlet valve assembly includes: an inner housing received within the inlet valve orifice such that the inner housing extends to the outside of the fuel pump housing and such that the outer periphery of the inner housing is sealed to the inner periphery of the inlet valve orifice to prevent fuel from radially passing between the inner housing and the inlet valve orifice to the outside of the fuel pump housing; an outer housing located outside the fuel pump housing and circumferentially surrounding the inner housing, wherein an annular chamber is radially defined between the inner housing and the outer housing and axially defined between the outer housing and the fuel pump housing; and a sealing ring made of an elastic material and annular in shape located within the annular chamber such that the sealing ring is axially compressed against the fuel pump housing and the outer housing.

[0005] The fuel pump with the sealing ring described herein minimizes the possibility that liquid from the external environment may reach the components of the inlet valve assembly, which could otherwise lead to undesirable operation.

[0006] The inlet valve assembly may include a solenoid assembly. The solenoid assembly may include: an inner housing; an outer housing; an electrode made of a magnetically conductive material located within the inner housing; and a coil formed of conductive wire, the coil circumferentially surrounding the electrode and positioned radially between the inner housing and the outer housing. When electrical energy is applied to the coil, this induces a magnetic attraction between the electrode and the valve element of the inlet valve assembly, causing the valve element to move toward the electrode.

[0007] In an embodiment of the fuel pump, the housing may include a flange that is annular in shape and extends inward toward the inner housing, such that when electrical energy is applied to the coil, the flange provides a path for magnetic flux to pass through. The sealing ring may be axially compressed against the flange.

[0008] In an embodiment of the fuel pump, the solenoid assembly may further include an overmolded member made of an electrically insulating material and filling the space between the coil and the housing. The overmolded member may include a central bore. The inner housing may extend into the central bore such that an annular gap is radially located between the inner housing and the central bore.

[0009] The sealing ring may be a first sealing ring; and the solenoid assembly may also include a second sealing ring, which is made of an elastic material and is annular in shape and located within the annular gap, such that the second sealing ring is radially compressed against the inner housing and the overmolded part.

[0010] The second sealing ring prevents liquid from entering the fuel pump from the outside.

[0011] The second sealing ring can be configured such that it is not exposed to fuel from the fuel pump.

[0012] The first sealing ring prevents liquid from outside the fuel pump from migrating into the inner housing.

[0013] The first sealing ring can be configured such that it is not exposed to fuel from the fuel pump.

[0014] For example, the solenoid assembly may further include an overmolded portion made of an electrically insulating material and filled between the coil and the housing. The overmolded portion may include a central bore; the inner housing extends into the central bore such that an annular gap is radially located between the inner housing and the central bore.

[0015] The solenoid assembly may also include a sealing cap that closes the central hole.

[0016] The sealing cap may include a sidewall that is interference-fitted into the central hole. The sealing cap may also include an end wall that extends radially outward from the sidewall abutting the overmolded member and limits how far the sealing cap can be inserted into the central hole.

[0017] The sealing cap can be configured such that it is not exposed to fuel from the fuel pump.

[0018] The sealing ring can be configured such that it is not exposed to fuel from the fuel pump.

[0019] Further features and advantages of the invention will become apparent when reading the following detailed description of preferred embodiments of the invention, which is given only by way of non-limiting example and with reference to the accompanying drawings. Attached Figure Description

[0020] The invention will be further described with reference to the accompanying drawings, in which:

[0021] Figure 1 This is a schematic diagram of a fuel system including a fuel pump according to the present invention;

[0022] Figure 2 yes Figure 1 A cross-sectional view of the fuel pump;

[0023] Figure 3 yes Figure 1 and Figure 2 Exploded isometric view of the fuel pump inlet valve assembly;

[0024] Figure 4 yes Figure 2 The image shows an enlarged view of a portion of the fuel pump inlet valve assembly in the first position;

[0025] Figure 5 yes Figure 4 The image shows a view of the inlet valve assembly in the second position;

[0026] Figure 6 yes Figure 4 and Figure 5 The image shows a view of the inlet valve assembly in the third position;

[0027] Figure 7 yes Figures 4 to 6 The image shows a view of the inlet valve assembly in the fourth position; and

[0028] Figure 8 A sealing cap according to this disclosure is shown. Detailed Implementation

[0029] According to a preferred embodiment of the present invention, and first referring to Figure 1A fuel system 10 for an internal combustion engine 12 is shown schematically. Typically, the fuel system 10 includes: a fuel tank 14 that holds a volume of fuel to supply the internal combustion engine 12 for its operation; a plurality of fuel injectors 16 that inject fuel directly into the respective combustion chambers (not shown) of the internal combustion engine 12; a low-pressure fuel pump 18; and a high-pressure fuel pump 20, wherein the low-pressure fuel pump 18 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, in some applications, the low-pressure fuel pump 18 can increase the fuel pressure to less than or equal to about 500 kPa, while the high-pressure fuel pump 20 can increase the fuel pressure to above about 14 MPa or even above 35 MPa. Although four fuel injectors 16 have been illustrated, it should be understood that fewer or more fuel injectors 16 may be provided.

[0030] As shown, the low-pressure fuel pump 18 can be located inside the fuel tank 14; however, it can alternatively be located outside the fuel tank 14. The low-pressure fuel pump 18 can be an electric fuel pump as is well known to those skilled in the art. The low-pressure fuel supply passage 22 provides fluid communication from the low-pressure fuel pump 18 to the high-pressure fuel pump 20. The fuel pressure regulator 24 can be configured such that it maintains a substantially uniform pressure within the low-pressure fuel supply passage 22 by allowing a portion of the fuel supplied by the low-pressure fuel pump 18 to return to the fuel tank 14 through the fuel return passage 26. Although the fuel pressure regulator 24 has been illustrated as being located in the low-pressure fuel supply passage 22 outside the fuel tank 14, it should be understood that the fuel pressure regulator 24 can be located inside the fuel tank 14 and can be integrated with the low-pressure fuel pump 18.

[0031] Please refer to the following: Figure 2 The high-pressure fuel pump 20 includes a fuel pump housing 28, which includes a plunger bore 30 extending along a plunger bore axis 32 and centered on the plunger bore axis. As shown, the plunger bore 30 can be defined by an assembly of inserts and directly by the fuel pump housing 28. The high-pressure fuel pump 20 also includes a pumping plunger 34 located within the plunger bore 30 and based on a rotating camshaft 36 from the internal combustion engine 12 (only when...). Figure 1(As shown in the diagram) The input reciprocates along the plunger bore axis 32 in the plunger bore 30. The 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. The inlet valve assembly 40 of the high-pressure fuel pump 20 is received within the inlet valve port 28a of the fuel pump housing 28, such that the inlet valve port 28a extends to the outside 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 the pump housing inlet passage 41 of the fuel pump housing 28 along the inlet valve port axis 28b, while the outlet valve assembly 42 is located within the outlet passage 43 of the fuel pump housing 28 and selectively allows fuel to flow from the pumping chamber 38 to the fuel injector 16 via the fuel guide 44, which is in fluid communication with each fuel injector. During operation, the reciprocating motion of the pumping plunger 34 causes the volume of the pumping chamber 38 to change during the intake stroke of the pumping plunger 34 (e.g., ...). Figure 2 During the downward direction (as directed in the middle), the volume of the pumping plunger 34 increases, wherein the plunger return spring 46 causes the pumping plunger 34 to move further downward, and conversely, the volume of the pumping chamber 38 increases during the compression stroke (as directed in the middle). Figure 2 During the upward movement (directed upwards), the camshaft 36 causes the pumping plunger 34 to move upwards against the force of the plunger return spring 46. In this way, fuel is selectively drawn into the pumping chamber 38 during the intake stroke, as will be described in more detail later, depending on the operation of the inlet valve assembly 40, and conversely, fuel is pressurized 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 the fuel injector 16. For clarity, the pumping plunger 34 in Figure 2 The solid line in the middle indicates the intake stroke, while the pumping plunger 34 is... Figure 2 The compression stroke is indicated by a dashed line. The high-pressure fuel pump 20 also includes a pressure reducing valve assembly 48, which is arranged downstream of the outlet valve assembly 42 to provide a fluid path back to the pumping chamber 38 if the pressure downstream of the outlet valve assembly 42 reaches a predetermined limit (which could create unsafe operating conditions if not relieved).

[0032] Typically, the outlet valve assembly 42 includes an outlet valve member 42a, an outlet valve seat 42b, and an outlet valve spring 42c. The outlet valve member 42a, illustrated only by way of non-limiting example, is a ball biased by the outlet valve spring 42c toward the outlet valve seat 42b, wherein the outlet valve spring 42c is selected to allow the outlet valve member 42a to open when a predetermined pressure differential is achieved between the pumping chamber 38 and the fuel rail 44. The outlet valve assembly 42 is oriented such that fuel is allowed to flow out of the pumping chamber 38 through the outlet valve assembly 42, but fuel is not allowed to flow into the pumping chamber 38 through the outlet valve assembly 42.

[0033] Typically, the pressure reducing valve assembly 48 includes a pressure reducing valve member 48a, a pressure reducing valve seat 48b, and a pressure reducing valve spring 48c. The pressure reducing valve member 48a, illustrated only by way of non-limiting example, is a ball biased towards the pressure reducing valve seat 48b by the pressure reducing valve spring 48c, wherein the pressure reducing valve spring 48c is selected to allow the pressure reducing valve member 48a to operate when a predetermined pressure differential is achieved between the pumping chamber 38 and the fuel rail 44. The pressure reducing valve assembly 48 is oriented such that fuel is allowed to flow through the pressure reducing valve assembly 48 into the pumping chamber 38, but fuel is not allowed to flow through the pressure reducing valve assembly 48 out of the pumping chamber 38.

[0034] Now, especially refer to Figures 3 to 7 The inlet valve assembly 40 is described below. The inlet valve assembly 40 includes a valve body 50, a valve core 52 located within the valve body 50, a check valve 54, and a solenoid assembly 55. The various components of the inlet valve assembly 40 will be described in more detail in the following paragraphs.

[0035] The valve body 50 extends along the axis 28b of the inlet valve hole, centered thereon, such that the valve body 50 extends from the first end 50a to the second end 50b. The valve body hole 58 extends from the first end 50a into the valve body 50 and terminates at the valve body end wall 60 extending to the second end 50b, such that the valve body hole 58 is preferably cylindrical. A first inlet channel 62 extends through the valve body 50, such that the first inlet channel 62 extends from the outer periphery 50c of the valve body 50 and leads to the valve body hole 58. A second inlet channel 64 (in...) Figure 3 Invisible in the middle, but in Figures 4 to 7 As shown in the figure, the first inlet channel 62 and the second inlet channel 64 extend through the valve body 50, such that the second inlet channel 64 extends from the outer periphery 50c of the valve body and leads to the valve body bore 58. As shown, the first inlet channel 62 and the second inlet channel 64 are axially spaced apart from each other along the inlet valve bore axis 28b, such that the second inlet channel 64 is axially located between the first end 50a of the valve body and the first inlet channel 62. Similarly, as shown in the figure, a plurality of first inlet channels 62 can be arranged such that each first inlet channel 62 is located at the same axial position along the inlet valve bore axis 28b; however, each first inlet channel 62 is spaced apart from the other first inlet channels 62 around the outer periphery 50c of the valve body. Although only one second inlet channel 64 is illustrated, it should be understood that a plurality of second inlet channels 64 can be arranged at the same axial position along the inlet valve bore axis 28b, but spaced apart from each other around the outer periphery 50c of the valve body.

[0036] A valve body central channel 66 extends through the valve body end wall 60, connecting the second end 50b of the valve body to the valve body bore 58. The central channel 66 extends about the inlet valve bore axis 28b and along it. Multiple valve body outlet channels 68 are provided in the valve body end wall 60, each extending through the end wall and connecting the second end 50b of the valve body to the valve body bore 58. Each outlet channel 68 is laterally offset from the central channel 66 and extends through the valve body end wall 60 in a direction parallel to the inlet valve bore axis 28b.

[0037] As shown in the figure, the outer periphery 50c of the valve body may include three sections of different diameters. The first portion 50d of the outer periphery 50c begins at the first end 50a of the valve body and extends to the second portion 50e of the outer periphery 50c, such that the diameter of the first portion 50d is smaller than the diameter of the second portion 50e. As shown in the figure, the first portion 50d may be completely outside the pump housing inlet passage 41, and the second portion 50e includes a first inlet passage 62 and a second inlet passage 64, such that each of the first and second inlet passages is in constant fluid communication with the portion of the pump housing inlet passage 41 upstream of the inlet valve assembly 40; that is, each of the first and second inlet passages is in constant fluid communication with the portion of the pump housing inlet passage 41 between the inlet valve assembly 40 and the low-pressure fuel pump 18. The third portion 50f of the outer periphery of the valve body 50c extends from the second portion 50e of the outer periphery of the valve body to the second end 50b of the valve body, such that the diameter of the third portion 50f is larger than the diameter of the second portion 50e. The third portion 50f of the outer periphery of the valve body is sealingly engaged with the pump housing inlet channel 41, thereby preventing fluid communication through the pump housing inlet channel 41 and through the inlet valve assembly 40 at the interface between the pump housing inlet channel 41 and the third portion 50f of the outer periphery of the valve body. Fluid communication through the pump housing inlet channel 41 and through the inlet valve assembly 40 is only possible through the valve body hole 58.

[0038] The valve core 52 is made of a magnetic material and is centered on and extends along the inlet valve port axis 28b from a first end 52a to a second end 52b. The valve core 52 includes a first portion 52c near the first end 52a and a second portion 52d near the second end 52b. The first portion 52c has an outer periphery 52e complementary to the valve body port 58, such that the dimensions of the outer periphery 52e and the valve body port 58 are designed to substantially prevent fuel from passing through the interface between the outer periphery 52e and the valve body port 58. As used herein, substantially preventing fuel from passing through the interface between the outer periphery 52e and the valve body port 58 encompasses allowing a small amount of fuel to pass through this interface, as will be readily recognized by those skilled in the art, which still allows the operation of the high-pressure fuel pump 20. The second portion 52d of the valve core includes a base portion 52f extending from the first portion 52c of the valve core, such that the diameter of the base portion 52f is smaller than the diameter of the first portion 52c, thereby providing a radially annular space between the base portion 52f and the valve body bore 58. The second portion 52d also includes an end portion 52g extending from the base portion 52f and terminating at a second end 52b of the valve core. The diameter of the end portion 52g is smaller than the diameter of the base portion 52f, thereby defining a shoulder 52h at which the end portion 52g meets the base portion 52f. The end portion 52g is sized to lie within the valve body central channel 66 of the valve body 50, allowing it to slide freely within the valve body central channel 66 in the direction of the inlet valve bore axis 28b. In use, the end portion 52g is used to dock with a check valve 54, which will be described in more detail later.

[0039] The first portion 52c of the valve core is provided with a valve core groove 70 extending radially inward from the outer periphery 52e of the valve core, such that the valve core groove 70 is annular in shape. The valve core groove 70 is selectively aligned or misaligned with the first inlet channel 62 and the second inlet channel 64 of the valve body to control fluid communication through the pump housing inlet channel 41, which will be described in more detail later. One or more valve core channels 72 are configured to extend from the valve core groove 70 through the first portion 52c of the valve core toward the second end 52b of the valve core, thereby providing fluid communication between the valve core groove 70 and the valve body outlet channel 68.

[0040] A valve core end bore 74 extends from the first end 52a of the valve core into the valve core 52. As shown, the valve core end bore 74 may include a first portion 74a and a second portion 74b, the first portion being an internally truncated cone, and the second portion being cylindrical and terminating at the bottom 74c. A valve core connection channel 76 provides fluid communication between the valve core recess 70 and the valve core end bore 74, such that, as shown, by way of non-limiting example only, the valve core connection channel 76 may be formed by a pair of vertically drilled holes.

[0041] The check valve 54 includes a check valve component 78 and a stroke limiter 80. The check valve 54 is positioned at the second end 52b of the valve core such that, as described in more detail below, the check valve component 78, when blocking the valve body outlet passage 68 (e.g., ...), ... Figures 5 to 7 The seating position (as shown in the diagram) and the unblocked valve body outlet passage 68 (as shown in the diagram) Figure 4 The check valve component 78 moves between the open positions shown in the diagram. The check valve component 78 includes a check valve center portion 78a, which is a flat plate having a check valve passage 78b extending therethrough, wherein, for clarity, has been... Figure 3 Only the selected check valve passage 78b is marked. The check valve passage 78b is arranged through the check valve center portion 78a such that it is not axially aligned with the valve body outlet passage 68. Multiple check valve legs 78c extend from the check valve center portion 78a, making them resilient and compliant. The free ends of the check valve legs 78c are fixed to the valve body second end 50b, for example, by welding. Therefore, when the pressure differential between the valve body orifice 58 and the pumping chamber 38 is sufficiently high, the resilient deformation of the check valve legs 78c allows the check valve center portion 78a to disengage from the valve core 52, thereby opening the valve body outlet passage 68. The stroke limiter 80 includes a stroke limiter ring 80a axially spaced from the valve body second end 50b to provide an allowable amount of displacement for the check valve component 78. The stroke limiter 80 also includes a plurality of stroke limiter legs 80b that provide axial spacing between the stroke limiter ring 80a and the second end 50b of the valve body. The stroke limiter legs 80b are integrally formed with the stroke limiter ring 80a and are fixed to the second end 50b of the valve body, for example, by welding.

[0042] The solenoid assembly 55 includes an inner housing 82, an electrode 84 located within the inner housing 82, a return spring 86, a valve core 88, a coil 90, a flux washer 91, an overmolded part 92, and an outer housing 94. The various components of the solenoid assembly 55 will be described in more detail in the following paragraphs.

[0043] The inner housing 82 is hollow and stepped both internally and externally, such that the first portion 82a of the inner housing is open and its diameter is larger than that of the second portion 82b of the inner housing, which is closed by the end wall 82c. The inner housing 82 is centered on and extends along the axis 28b of the inlet valve port. The first portion 82a of the inner housing is received within the inlet valve port 28a, thereby sealing the first portion 82a of the inner housing to the fuel pump housing 28 to prevent fuel leakage from the pump housing inlet passage 41 to the outside of the fuel pump housing 28. This seal can be achieved, by way of non-limiting example only, through one or more of the following: an interference fit between the first portion 82a of the inner housing and the inlet valve port 28a, welding around the inner corner where the first portion 82a of the inner housing meets the fuel pump housing 28, and adhesives. An annular gap is provided between the inner periphery of the first portion 82a of the inner housing and the second portion 50e of the outer periphery of the valve body to provide fluid communication between the pump housing inlet passage 41 and the valve body second inlet passage 64. The inner periphery of the second part 82b of the inner housing mates with the first part 50d of the outer periphery of the valve body to prevent fuel from flowing between the interface of the outer periphery of the second part 82b of the inner housing and the first part 50d of the outer periphery of the valve body.

[0044] The electrode 84 is made of a magnetically conductive material and is received within the second portion 82b of the inner housing, such that the electrode 84 extends along the axis 28b of the inlet valve hole, centered on it. The first end 84a of the electrode is truncated conical, such that the angle of the first end 84a is complementary to the angle of the first portion 74a of the valve core end hole. In this way, the first end 84a of the electrode is received within the first portion 74a of the valve core end hole. The second end 84b of the electrode, opposite the first end 84a, is located at the closed end of the inner housing 82. An electrode hole 84c extends axially from the first end 84a through the electrode 84 to the second end 84b, such that the larger diameter portion of the electrode hole 84c extends from the first end 84a into the electrode 84, thereby defining an electrode shoulder 84d facing the bottom 74c of the valve core end hole. The return spring 86 is partially received within the electrode hole 84c, such that the return spring 86 abuts against the electrode shoulder 84d. The return spring 86 is also partially received within the second portion 74b of the valve spool end hole, and abuts against the bottom 74c of the valve spool end hole. The return spring 86 is held in compression between the electrode shoulder 84d and the bottom 74c of the valve spool end hole, and in this way, the return spring 86 biases the valve spool 52 away from the electrode 84.

[0045] The valve core 88 is made of an electrically insulating material (e.g., plastic) and extends circumferentially around and along the axis 28b of the inlet valve hole, such that the valve core 88 circumferentially surrounds the second part 82b of the inner housing in a close-fitting relationship. The coil 90 is a winding of conductive wire wound around the outer periphery of the valve core 88, such that the coil 90 circumferentially surrounds the pole piece 84. Therefore, when current is applied to the coil 90, the valve core 52 is magnetically attracted to and moves toward the pole piece 84, and when no current is applied to the coil 90, the valve core 52 moves away from the pole piece 84 by means of a return spring 86. A more detailed description of the operation will be provided later.

[0046] The outer casing 94 circumferentially surrounds the inner casing 82, valve core 88, and coil 90, such that the valve core 88 and coil 90 are radially located between the inner casing 82 and the outer casing 94. An annular chamber 96 is radially formed between the first portion 82a of the inner casing and the outer casing 94, such that the annular chamber 96 is axially located between the exterior of the fuel pump housing 28 and the flange 94a of the outer casing 94, the flange 94a being annular in shape and extending inward toward the second portion 82b of the inner casing. When current is applied to the coil 90, the flange 94a provides a path for the magnetic flux to pass through, resulting in a very small radial clearance between the inner casing 82 and the flange 94a. A first sealing ring 98 is located within the annular chamber 96 and is axially compressed between the fuel pump housing 28 and the flange 94a by the fuel pump housing and the flange 94b. The first sealing ring 98 is made of an elastic material, the specific composition of which is selected based on environmental factors such as temperature and the liquids that may come into contact with the first sealing ring 98, as readily apparent to those skilled in the art. The first sealing ring 98 prevents liquids from the external environment from migrating into the inner housing 82, where liquids could otherwise accumulate and become difficult to dry. This could lead to deterioration of 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, if liquid accumulation is allowed, crack corrosion erosion could occur. It is important to note that the first sealing ring 98 does not function in sealing the fuel within the high-pressure fuel pump 20; that is, the first sealing ring 98 is not exposed to the fuel within the high-pressure fuel pump 20 and is configured to prevent the intrusion of liquids present in the external environment of the high-pressure fuel pump 20. In addition to its primary purpose of preventing the intrusion of liquids present in the external environment of the high-pressure fuel pump 20, the first sealing ring 98 also provides suppression of vibrations and audible noises generated during operation of the high-pressure fuel pump 20 that could otherwise be transmitted into the environment.

[0047] The flux washer 91 is located within the housing 94 such that its outer periphery engages with the inner periphery of the housing 94, and that the valve core 88 and coil 90 are axially positioned between the flange 94a and the flux washer 91. When current is applied to the coil 90, the flux washer 91 provides a path for the magnetic flux to pass through, resulting in a very small radial gap between the inner housing 82 and the flux washer 91.

[0048] The overmolded member 92 is an electrically insulating material (e.g., plastic) that fills the gap between the valve core 88 / coil 90 and the housing 94, such that the overmolded member 92 extends axially from the housing 94 to define an electrical connector 100, which includes terminals (not shown) connected to opposite ends of the coil 90. The electrical connector 100 is configured to mate with a complementary electrical connector (not shown) for supplying current to the coil 90 in use. The overmolded member 92 includes a central bore 92a that extends along the inlet valve bore axis 28b to a flux washer 91. An inner housing 82 extends into the central bore 92a, such that an annular gap 102 is formed radially between the overmolded member 92 and the inner housing 82. A second sealing ring 104 is located within the annular gap 102 and is radially compressed between the overmolded member 92 and the inner housing 82. The second sealing ring 104 is made of an elastic material, the specific composition of which is selected based on environmental factors such as temperature and the liquid that may come into contact with the second sealing ring 104, as readily apparent to those skilled in the art. Unlike the first sealing ring 98, which has a circular cross-sectional shape before installation, the second sealing ring 104 can be elongated in a direction parallel to the inlet valve orifice axis 28b before installation to provide structural integrity for the second sealing ring 104, since the second sealing ring 104 is not trapped in a direction parallel to the inlet valve orifice axis 28b. This cross-sectional shape also prevents the second sealing ring 104 from rolling during installation into the annular gap 102. The second sealing ring 104 prevents liquid from the external environment from migrating into the small radial gap between the inner housing 82 and the flux gasket 91, where liquid could otherwise accumulate and be difficult to dry, and where crack corrosion could occur if liquid accumulation is allowed. It is important to note that the second sealing ring 104 does not function in sealing the fuel within the high-pressure fuel pump 20; that is, the second sealing ring 104 is not exposed to the fuel within the high-pressure fuel pump 20 and is configured to prevent the intrusion of liquids present in the external environment of the high-pressure fuel pump 20. In addition to its primary purpose of preventing the intrusion of liquids present in the external environment of the high-pressure fuel pump 20, the second sealing ring 104 also provides suppression of vibrations and audible noises generated during operation of the high-pressure fuel pump 20 that would otherwise be transmitted into the environment.

[0049] Special reference Figure 4 To describe the operation of the high-pressure fuel pump 20, and in particular the inlet valve assembly 40, Figure 4 The diagram shows the valve spool 52 in a first position due to the lack of current supply to the coil 90 of the solenoid assembly 55. When no current is supplied to the coil 90, the return spring 86 pushes the valve spool 52 away from the electrode 84 until the valve spool shoulder 52h abuts against the valve body end wall 60. This allows the end portion 52g of the valve spool 52 to protrude beyond the second end 50b of the valve body, such that the end portion 52g holds the check valve member 78 in an off-seat position to allow fluid flow through the valve body outlet passage 68 and to maintain fluid communication between the valve body outlet passage 68 and the pumping chamber 38. Also in the first position, the valve spool recess 70 is aligned with the first inlet passage 62 of the valve body; however, it is noteworthy that the valve spool recess 70 is not aligned with the second inlet passage 64 of the valve body. In this way, the valve spool 52 holds the check valve member 78 in the off-seat position, and the first inlet passage 62 of the valve body is in fluid communication with the valve body outlet passage 68. It should be noted that in the first position, the alignment between the valve core recess 70 and the valve body first inlet passage 62 provides a path to the pump housing inlet passage 41. In this way, the first position provides the default position for limp-home operation of the high-pressure fuel pump 20, meaning that if power to the solenoid assembly 55 is unintentionally interrupted, a sufficient amount and pressure of fuel will be supplied to the fuel injector 16 via the low-pressure fuel pump 18 for continuous operation of the internal combustion engine 12, although no fuel is pressurized by the high-pressure fuel pump 20 because the check valve assembly 78, held in the off-seat position by the valve core 52, prevents fuel from being pressurized by the pump plunger 34. It should be noted that the path to the pump housing inlet passage 41, enabling limp-home operation of the high-pressure fuel pump 20, can also be achieved using only a pressure reducing valve, namely the pressure reducing valve assembly 48.

[0050] Now, please refer to Figure 5The valve core 52 is shown in a second position, caused by current 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 core 52 is attracted to the pole 84, causing the valve core 52 to move toward the pole 84 and compressing the return spring 86 to a greater extent than in the first position. The valve core connection channel 76 allows fuel located between the valve core 52 and the pole 84 to shift toward the valve body outlet channel 68 during the movement of the valve core 52 toward the pole 84, and also allows equal pressure at each axial end of the valve core 52. In the second position, the end portion 52g is positioned so that it no longer protrudes beyond the second end 50b of the valve body, and thus, the check valve member 78 moves to a seated position that prevents fluid from flowing through the valve body outlet channel 68 into the valve body bore 58. Also in the second position, the valve core recess 70 is not aligned with the valve body first inlet passage 62, nor with the valve body second inlet passage 64, thus preventing fuel from entering or leaving the valve body bore 58 through the valve body first inlet passage 62 and valve body second inlet passage 64. Therefore, the valve body first inlet passage 62 and valve body second inlet passage 64 are not in fluid communication with the valve body outlet passage 68. The valve core 52 in the second position is used when the internal combustion engine 12 is running but not requesting fuel supply from the fuel injector 16, such as during a fuel deceleration cutoff event that may occur when the vehicle is coasting and no fuel is ordered. In this way, the second position prevents fuel supply to the fuel injector 16.

[0051] Now, please refer to Figure 6The valve core 52 is shown in a third position due to the current supplied to the coil 90 of the solenoid assembly 55 at a second duty cycle, which is greater than the first duty cycle used to achieve the second position of the valve core 52. When current is supplied to the coil 90 at the second duty cycle, the valve core 52 is attracted to the pole 84, causing the valve core 52 to move toward the pole 84 and compressing the return spring 86 to a greater extent than in the second position. As in the second position, the third position causes the end portion 52g to be positioned so that it no longer protrudes beyond the second end 50b of the valve body, and thus the check valve member 78 moves to a seated position that prevents fluid from flowing through the valve body outlet passage 68 into the valve body bore 58. However, it should be noted that when the pressure difference between the valve body bore 58 and the pumping chamber 38 is sufficiently high, i.e., during the intake stroke, the check valve member 78 can move to an unseated position. Also in the third position, the valve core recess 70 is not aligned with the first inlet passage 62 of the valve body; however, the valve core recess 70 is now aligned with the second inlet passage 64 of the valve body, and in this way, fuel is allowed to flow through the second inlet passage 64 of the valve body to the valve body bore 58. Therefore, during the intake stroke of the pumping plunger 34, a pressure differential is generated that allows fuel to flow through the second inlet passage 64 of the valve body through the inlet valve assembly 40, thereby moving the check valve member 78 to the off-seat position to allow fuel to flow into the pumping chamber 38. During the compression stroke of the pumping plunger 34, the pressure within the pumping chamber 38 increases, causing the check valve member 78 to move to the seated position, which prevents fuel from flowing from the pumping chamber 38 into the valve body bore 58 and allows pressurized fuel within the pumping chamber 38 to exit through the outlet valve assembly 42. When a lighter output torque is required from the internal combustion engine 12, a third-position valve spool 52 is used. It should be noted that the alignment of the valve spool groove 70 with the valve body second inlet passage 64 provides a restricted passage that meters a small amount of fuel into the pumping chamber 38 during the intake stroke of the pumping plunger 34 to support the fuel supply of the internal combustion engine 12 under light load.

[0052] Now, please refer to Figure 7The valve core 52 is shown in the fourth position, caused by supplying current to the coil 90 of the solenoid assembly 55 with a third duty cycle, which is larger than the second duty cycle used to achieve the third position of the valve core 52. When current is supplied to the coil 90 with the third duty cycle, the valve core 52 is attracted to the pole 84, causing the valve core 52 to move toward the pole 84 and compressing the return spring 86 to a greater extent than in the third position. As in the second and third positions, the fourth position causes the end portion 52g to be positioned so that it no longer protrudes beyond the second end 50b of the valve body, and thus, the check valve member 78 moves to the seated position, which prevents fuel from flowing through the valve body outlet passage 68 into the valve body bore 58. However, it should be noted that when the pressure difference between the valve body bore 58 and the pumping chamber 38 is sufficiently high, i.e., during the intake stroke, the check valve member 78 can move to the unseated position. Also in the fourth position, the valve core recess 70 is not aligned with the first inlet passage 62 of the valve body; however, the valve core recess 70 is now aligned with the second inlet passage 64 of the valve body, and in this way, fuel is allowed to flow through the second inlet passage 64 of the valve body to the valve body bore 58. Therefore, during the intake stroke of the pumping plunger 34, a pressure differential is generated that allows fuel to flow through the second inlet passage 64 of the valve body and through the inlet valve assembly 40, thereby moving the check valve member 78 to the off-seat position to allow fuel to flow into the pumping chamber 38. During the compression stroke of the pumping plunger 34, the pressure within the pumping chamber 38 increases, causing the check valve member 78 to move to the seated position, which prevents fuel from flowing from the pumping chamber 38 into the valve body bore 58 and allows pressurized fuel within the pumping chamber 38 to be discharged through the outlet valve assembly 42. As should now be apparent, the third and fourth positions of valve spool 52 are nearly identical. However, the difference between the fourth and third positions is that the alignment of the valve spool recess 70 with the valve body second inlet passage 64 is less restrictive than in the third position. Therefore, when higher output torque is required from the internal combustion engine 12, the fourth position of valve spool 52 is used because the alignment of the valve spool recess 70 with the valve body second inlet passage 64 provides a less restricted passage, allowing a larger amount of fuel to be metered into the pumping chamber 38 during the intake stroke of the pumping plunger 34 compared to the third position, thus supporting the fuel supply of the internal combustion engine 12 under high loads.

[0053] As should now be clear, different duty cycles can be provided to change the amount of fuel metered to the pumping chamber 38. In the pumping chamber, different duty cycles result in changes in the degree of alignment between the valve core recess 70 and the valve body second inlet passage 64, thereby changing the degree of restraint. In other words, the third and fourth positions described above are merely examples of the positions of the valve core 52, and other duty cycles can be provided to supply different metered amounts of fuel to the pumping chamber 38 to achieve different output torques of the internal combustion engine 12. The electronic control unit 106 can be used to supply current to the coil 90 at various duty cycles described herein. The electronic control unit 106 can receive input from the pressure sensor 108, which senses the pressure within 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 be varied based on the command torque desired to be generated by the internal combustion engine 12.

[0054] Although the inner housing 82 has been illustrated and described herein as being directly joined and welded to the fuel pump housing 28, it should be understood that an intermediate element, such as a sleeve (not shown), may be radially disposed between the inner housing 82 and the fuel pump housing 28, and this intermediate element will be considered as the fuel pump housing 28 within the scope of this disclosure.

[0055] In addition to or as an alternative to the second sealing ring 104, a structure such as... can be provided. Figure 8The sealing cap 110 shown closes the open end of a central bore 92a, which is opposite to the flux-cored washer 91. The sealing cap 110 may include a sidewall 110a, which is annular in shape and is fitted into the central bore 92a in an interference fit, for example by one or more annular ribs 100b circumferentially surrounding the sidewall 110a, to hold the sealing cap 110 to the overmolded part 92 and prevent liquid intrusion. The sealing cap 110 may also include an end wall 110c, which 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 is inserted into the central bore 92a. The sealing cap 110 is made of an elastic material, the specific composition of which is selected based on environmental factors such as temperature and the liquid that may come into contact with the first sealing ring 98, as readily apparent to those skilled in the art. The sealing cap 110 prevents liquid from entering the central hole 92a, thereby preventing liquid migration to areas that could lead to deterioration, as described above with respect to the second sealing ring 104. It is important to note that the sealing cap 110 does not function in sealing the fuel within the high-pressure fuel pump 20; that is, the sealing cap 110 is not exposed to the fuel within the high-pressure fuel pump 20 and is configured to prevent the intrusion of liquids present in the external environment of the high-pressure fuel pump 20. In addition to its primary purpose of preventing the intrusion of liquids present in the external environment of the high-pressure fuel pump 20, the sealing cap 110 also provides suppression of vibrations and audible noise generated during operation of the high-pressure fuel pump 20 that would otherwise be transmitted to the environment.

[0056] The high-pressure fuel pump 20, as described herein, having one or more of a first sealing ring 98, a second sealing ring 104, and a sealing cap 110, minimizes the possibility that liquid from the external environment may reach the components of the inlet valve assembly 40 and the solenoid assembly 55, which could otherwise lead to undesirable operation of the inlet valve assembly 40 or the solenoid assembly 55. Furthermore, vibrations and audible noise generated by the operation of the high-pressure fuel pump 20 can be suppressed.

[0057] Although the invention has been described according to preferred embodiments thereof, it is not intended to be limited in this way, but rather to the scope set forth in the following claims.

Claims

1. A fuel pump (18) comprising: Fuel pump housing (28) having a pumping chamber (38) defined therein and an inlet valve port (28a) extending to the outside of the fuel pump housing (28) along the axis (28b). A pumping plunger (34) reciprocates within a plunger bore, such that the intake stroke of the pumping plunger (34) increases the volume of the pumping chamber (38), and the compression stroke of the pumping plunger (34) decreases the volume of the pumping chamber (38); and An inlet valve assembly (40) that: 1) selectively provides fluid communication between the inlet (20a) of the fuel pump (18) and the pumping chamber (38); and 2) selectively prevents fluid communication between the inlet (20a) of the fuel pump (18) and the pumping chamber (38), the inlet valve assembly (40) comprising: An inner housing (82) is received within the inlet valve port (28a) such that the inner housing (82) extends to the outside of the fuel pump housing (28) and such that the outer periphery of the inner housing (82) is sealed to the inner periphery of the inlet valve port (28a) to prevent fuel from radially passing between the inner housing (82) and the inlet valve port (28a) to the outside of the fuel pump housing (28); An outer casing (94) is located outside the fuel pump housing (28) and circumferentially surrounds the inner housing (82), wherein an annular chamber (96) is radially defined between the inner housing (82) and the outer casing (94), and axially defined between the outer casing (94) and the fuel pump housing (28); and A sealing ring (98), made of an elastic material and in an annular shape, is located within the annular chamber (96) such that the sealing ring (98) is axially compressed against the fuel pump housing (28) and the outer casing (94).

2. The fuel pump (18) according to claim 1, wherein, The inlet valve assembly (40) includes a solenoid assembly (55), the solenoid assembly comprising: The inner shell (82); The outer casing (94); The electrode (84) is made of a magnetically permeable material and is located inside the inner housing (82).

3. The fuel pump (18) according to claim 2, wherein the solenoid assembly (55) further comprises a coil (90) formed of conductive wire, the coil being circumferentially surrounding the pole piece (84) and such that the coil (90) is radially positioned between the inner housing (82) and the outer housing (94), wherein, The electrical energy applied to the coil (90) causes a magnetic attraction between the pole (84) and the valve element (52) of the inlet valve assembly (40), causing the valve element (52) to move toward the pole.

4. The fuel pump (18) according to claim 3, wherein: The outer casing (94) includes a flange (94a) that is annular in shape and extends inward toward the inner casing (82) such that when electrical energy is applied to the coil (90), the flange (94a) provides a path for magnetic flux to pass through; and The sealing ring (98) is axially compressed and abuts against the flange.

5. The fuel pump (18) according to claim 3 or 4, wherein: The solenoid assembly (55) further includes an overmolded part (92) made of an electrically insulating material and filled between the coil (90) and the housing (94), the overmolded part (92) including a central hole (92a).

6. The fuel pump according to claim 5, wherein, The inner housing (82) extends into the central hole (92a) such that the annular gap (102) is located radially between the inner housing (82) and the central hole (92a).

7. The fuel pump (18) according to claim 6, wherein, The sealing ring is the first sealing ring (98); and The solenoid assembly (55) further includes a second sealing ring (104) made of an elastic material and being annular in shape and located within the annular gap (102), such that the second sealing ring (104) is radially compressed against the inner housing (82) and the overmolded member (92).

8. The fuel pump (18) according to claim 7, wherein, The second sealing ring (104) prevents liquid from entering from the outside of the fuel pump (18).

9. The fuel pump (18) according to claim 7, wherein, The second sealing ring (104) is configured not to be exposed to fuel from the fuel pump (18).

10. The fuel pump (18) according to claim 7, wherein, The first sealing ring (98) prevents liquid from outside the fuel pump (18) from migrating into the inner housing (82).

11. The fuel pump (18) according to claim 9, wherein, The first sealing ring (98) is configured not to be exposed to fuel from the fuel pump (18).

12. The fuel pump (18) according to claim 5, wherein, The solenoid assembly also includes a sealing cap (110) that closes the central hole (92a).

13. The fuel pump (18) according to claim 12, wherein, The sealing cap (110) includes: Sidewall (110a), said sidewall being located within the central hole (92a) with an interference fit; and An end wall (110c) extends radially outward from the side wall (110a), abutting against the overmolded part and limiting how far the sealing cap (110) can be inserted into the central hole (92a).

14. The fuel pump (18) according to claim 13, wherein, The sealing cap (110) is configured not to be exposed to fuel from the fuel pump.

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