Low-pressure pump for fuel system and starting fuel injection check valve of low-pressure pump

Abstract

A fuel system for an internal combustion engine includes a low pressure pump with a start-up fueling check valve. A start-up fuel check valve extends into the outlet flow path at a junction of the outlet flow path and a start-up fuel flow path connecting the inlet flow path of the low pressure pump to the outlet flow path.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of the filing date of U.S. Provisional Application No. 63 / 625,559, filed on January 26, 2024, which is incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to fuel systems for internal combustion engines, and more particularly but not exclusively to a priming check valve for a low - pressure pump of a fuel system. Background Art

[0004] Common - rail direct fuel injection is typically used in fuel systems for internal combustion engines, such as diesel engines. A common - rail direct fuel system generally includes a low - pressure pump operatively connected and attached to a high - pressure pump. The low - pressure pump directs fuel to the high - pressure pump, which then increases the fuel pressure to meet the fueling pressure requirements. The pressurized fuel from the high - pressure pump is sent to a rail that balances the pressure based on the number of fuel injectors connected, and then the fuel injectors inject the fuel into the engine.

[0005] In response to a key - on event, priming of the fuel system can be accomplished by operating an electric lift pump located at or near the fuel tank. The low - pressure pump includes a priming passage with a check valve that opens to allow priming of the fuel system and closes once the electric lift pump is turned off. After priming, the low - pressure pump includes an internal gear driven by the operation of the engine to direct the pressurized fuel to the high - pressure pump.

[0006] Due to low - pressure pump design, fuel system piping configuration, downstream fuel system restrictions, and / or pump speed, pressure pulsations are generated downstream of the low - pressure pump. To limit the outlet pressure, the low - pressure pump typically includes a pressure regulating valve on the outlet side of the low - pressure pump. However, the allowed flow rate and pressure fluctuations can cause durability problems for the internal components of the low - pressure pump, such as the priming check valve. Therefore, improvements to the low - pressure pump for a fuel system of an internal combustion engine are needed. Summary of the Invention

[0007] The present disclosure includes a low - pressure pump that pumps fuel for a fuel system, where a priming check valve is located between the inlet and outlet of the low - pressure pump. The priming check valve is operable to regulate fuel flow from a fuel source from the inlet of the low - pressure pump to the outlet of the low - pressure pump during priming of the fuel system downstream of the low - pressure pump.

[0008] In an embodiment of the present disclosure, a fuel system for an internal combustion engine is provided. The fuel system includes a fuel pump having an inlet flow path for receiving fuel from a fuel source. The fuel pump has an outlet flow path for outputting pressurized fuel. The fuel pump includes a start-of-injection fuel flow path extending from the inlet flow path to the outlet flow path, and the start-of-injection fuel flow path includes a start-of-injection seat. A pumping flow path is connected to the inlet flow path downstream of the start-of-injection fuel flow path and is connected to the outlet flow path upstream of the start-of-injection fuel flow path. The fuel system further includes a start-of-injection check valve connecting the start-of-injection fuel flow path to the outlet flow path. The start-of-injection check valve includes a valve member and a valve seat in the outlet flow path. The valve member engages the start-of-injection seat in the start-of-injection fuel flow path to close the start-of-injection fuel flow path. The valve member engages the valve seat located in the outlet flow path to open the start-of-injection fuel flow path.

[0009] In an embodiment of the present disclosure, a start-of-injection check valve for a low-pressure pump of a fuel system is provided. The start-of-injection check valve includes a base configured to engage a housing of the low-pressure pump, an elongate shaft extending from the base, and a seat located at an outer end of the shaft. The start-of-injection check valve further includes a spring surrounding the shaft and a valve member supported on the spring. The spring biases the valve member away from the valve seat to a first position, and the spring compresses when the valve member is displaced to engage the valve seat. The shaft supports a majority of the length of the spring in the first position.

[0010] In an embodiment of the present disclosure, a low-pressure pump includes a housing and a start-of-injection check valve engaged to the housing. The housing includes an inlet flow path for receiving fuel from a fuel source and an outlet flow path for outputting pressurized fuel. The housing further includes a start-of-injection fuel flow path extending from the inlet flow path to the outlet flow path. The start-of-injection fuel flow path includes a start-of-injection path seat. The housing further includes a pumping flow path connected to the inlet flow path downstream of the start-of-injection fuel flow path. The pumping flow path is further connected to the outlet flow path upstream of the start-of-injection fuel flow path. The start-of-injection check valve includes a shaft extending into the outlet flow path to a valve seat in the outlet flow path, a spring surrounding the shaft, and a valve member supported by the spring. The spring biases the valve member to engage the start-of-injection path seat to close the start-of-injection fuel flow path, and the valve member is displaced to compress the spring and engage the valve seat in the outlet flow path to open the start-of-injection fuel flow path.

[0011] This summary is neither intended to identify the key or essential features of the claimed subject matter nor to serve as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects and benefits will become apparent from the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The description herein refers to the accompanying drawings, wherein like reference numerals refer to like parts throughout the several views, and in which:

[0013] Figure 1 is a schematic block diagram of an example fuel system of an internal combustion engine according to an embodiment of the present disclosure.

[0014] Figure 2 According to the embodiment of the present disclosure Figure 1 Elevation view of the low-pressure pump of the fuel system.

[0015] Figure 3 yes Figure 2 sectional view of a low pressure pump illustrating a priming check valve according to an embodiment of the present disclosure.

[0016] Figure 4 yes Figure 2 Cross-section of the low-pressure pump with the priming check valve in the closed position.

[0017] Figure 5 yes Figure 2 Cross-section of the low-pressure pump with the priming check valve in the closed position.

[0018] Figure 6 is a cross-sectional view of the priming check valve in the housing of the low-pressure pump in the closed position. DETAILED DESCRIPTION

[0019] In order to clearly, concisely, and accurately describe the illustrative embodiments of the present disclosure, the manner and process of making and using the present disclosure, and to enable the practice, making, and use of the present disclosure, reference will now be made to certain exemplary embodiments, including those shown in the drawings, and specific language will be used to describe the present disclosure. It will be understood, however, that no limitation of the scope of the present invention is thereby intended, and that the present invention encompasses and protects such alterations, modifications, and further applications of the exemplary embodiments as will occur to those skilled in the art.

[0020] refer to Figures 1 to 5, which shows a fuel system 100 for an internal combustion engine 102. In an embodiment of the present disclosure, the fuel system 100 includes a low-pressure pump 104 having an inlet flow path 106 for receiving fuel from a fuel source 110. The fuel pump 104 has an outlet flow path 108 for outputting pressurized fuel to the fuel system 100. The low-pressure pump 104 includes a start injection fuel flow path 112 extending from the inlet flow path 106 to the outlet flow path 108. The start injection fuel flow path 112 includes a start injection fuel path seat 146. The fuel system 100 includes a pumping flow path 148 connected to the inlet flow path 106 downstream of the start injection fuel flow path 112. The pumping flow path 148 is further connected to the outlet flow path 108 upstream of the start injection fuel flow path 112. A start injection check valve 130 connects the start injection fuel flow path 112 to the outlet flow path 108. The start injection check valve 130 includes a valve member 140 and a valve seat 138 in the outlet flow path 108. The valve member 140 engages with the start injection fuel path seat 146 to close the start injection fuel flow path 112, and is displaced to engage with the valve seat 138 in the outlet flow path 108 to open the start injection fuel flow path 112.

[0021] In an embodiment of the present disclosure, a start injection check valve 130 for a low-pressure pump 104 of a fuel system 100 is provided. The start injection check valve 130 includes a base 132 that can be engaged with the low-pressure pump 104 and an elongated shaft 134 extending from the base 132. The elongated shaft 134 includes a valve seat 138 at an end 144 of the shaft 134 opposite the base 132. A spring 142 is positioned around the shaft 134, and the valve member 140 is supported by the spring 142. The spring 142 biases the valve member 140 away from the valve seat 138 to a first position, and the spring 142 compresses when the valve member 140 moves towards engagement with the valve seat 138. The shaft 134 supports most of the length of the spring 142 in the first position.

[0022] In an embodiment of the present disclosure, a low-pressure pump 104 is provided for a fuel system 100 of an internal combustion engine 102. The low-pressure pump 104 includes a housing 180 and a start-of-injection check valve 130 coupled to the housing 180. The housing 180 includes an inlet flow path 106 for receiving fuel from a fuel source 110, and an outlet flow path 108 for outputting pressurized fuel. The housing 180 further includes a start-of-injection flow path 112 extending from the inlet flow path 106 to the outlet flow path 108. The start-of-injection flow path 112 includes a start-of-injection path seat 146. The housing 180 further includes a pumping flow path 148 connected to the inlet flow path 106 downstream of the start-of-injection flow path 112. The pumping flow path 148 is further connected to the outlet flow path 108 upstream of the start-of-injection flow path 112. The start-of-injection check valve 130 includes a shaft 134 that extends into the outlet flow path 108 to a valve seat 138 in the outlet flow path 108. A spring 142 surrounds the shaft 134, and a valve member 140 is supported by the spring 142. The spring 142 biases the valve member 140 to engage the start-of-injection path seat 146, thereby closing the start-of-injection flow path 112, and the valve member 140 is displaced to compress the spring 142 and engage the valve seat 138 in the outlet flow path 108, thereby opening the start-of-injection flow path 112.

[0023] Figure 1 The fuel system 100 therein is configured to supply fuel 114 from the fuel source 110 to the internal combustion engine 102. The fuel source 110 can be, for example, a fuel tank. In an embodiment, the fuel source 110 includes an electric lift pump 115 to prime the fuel system 100, as further discussed below. The fuel system 100 includes a lower-pressure or low-pressure pump 104 that pressurizes the fuel and supplies the fuel to an inlet downstream of a higher-pressure or high-pressure pump 116. The low-pressure pump 104 is located upstream of the high-pressure pump 116. A camshaft 124 can be provided to mechanically drive each of the low-pressure pump 104 and the high-pressure pump 116. The camshaft 124 can be connected to and driven by an output shaft 126 of the engine 102.

[0024] The high-pressure pump 116 further pressurizes the fuel and supplies it to a fuel rail 118, and the fuel rail distributes the pressurized fuel to a plurality of fuel injectors 120. The engine 102 includes cylinders 122, and each cylinder receives fuel from one or more of the fuel injectors 120 connected to the rail 118. It should be understood that Figure 1 only some components of the fuel system 100 are shown. Other details and components, such as a start-of-injection pump, filters, valves, drain pipes, bypasses, pipes, venturis, etc., are omitted for clarity and / or for being irrelevant to the present disclosure.

[0025] Further reference is made to Figures 2 to 5, the low-pressure pump 104 includes a pump housing 180 having an inlet 176 connected to the inlet flow path 106 and an outlet 178 connected to the outlet flow path 108. The inlet 176 of the low-pressure pump 104 receives fuel from the fuel source 110. The fuel flows through the inlet flow path 106, is pressurized by the low-pressure pump 104, and is provided to the outlet flow path 108, where the fuel passes through the outlet 178 and is provided to the inlet of the high-pressure pump 116. The flow of fuel through the inlet flow path 106 is controlled by the operation of the electric lift pump 115 to supply fuel to the low-pressure pump 104, or by the suction force generated by the gear assembly 150 in the low-pressure pump 104.

[0026] The priming fuel flow path 112 extends between the inlet flow path 106 and the outlet flow path 108 and fluidly connects the inlet flow path to the outlet flow path. A priming fuel check valve 130 is provided at the junction between the priming fuel flow path 112 and the outlet flow path 108. The priming fuel check valve 130 includes a valve member 140 that is biased by a spring 142 to engage a priming fuel path seat 146. In the illustrated embodiment, the priming fuel path seat 146 includes a conical, frustoconical shape configured to receive the valve member 140 in a manner that fully closes the priming fuel flow path 112 during non-priming fuel operation modes.

[0027] During the operation of the electric lift pump 115, such as during a key-on event, the fuel pressure generated by the electric lift pump 115 is sufficient to unseat the valve member 140 from the priming fuel path seat 146. The valve member 140 is movable into the outlet flow path 108 until it engages a valve seat 138, thereby opening the priming fuel flow path 112 to allow priming fueling of the fuel system 100 downstream of the low-pressure pump 104. In the position engaged with the valve seat 138, the valve member 140 may extend between the outlet flow path 108 and the priming fuel flow path 112 such that the valve member 140 cannot fully move into the outlet flow path 108.

[0028] The low-pressure pump further includes a pumping flow path 148 connected to the inlet flow path 106 downstream of the priming fuel flow path 112. The pumping flow path 148 is further connected to the outlet flow path 108 upstream of the priming fuel flow path 112. The gear assembly 150 is located in the pumping flow path 148. The gear assembly 150 is driven by a camshaft 124 to pump fluid from the inlet flow path 106 to the outlet flow path 108.

[0029] In an embodiment, the gear assembly 150 includes a first gear 152 and a second gear 154 that meshes with the first gear 150. In an embodiment, one of the gears 152, 154 is a driven gear and the other gear is an idler gear. In the illustrated embodiment, the gear assembly is an external gear assembly. However, other types of gear assemblies are also contemplated, including internal gear assemblies.

[0030] The low-pressure pump 104 further includes a pressure relief valve 160 fluidly connected to the outlet flow path 108. The pressure relief valve 160 includes an elongate valve member 162 having a passage 164 to receive fluid from the outlet flow path 108. The valve member 162 includes a head 166 that is biased by a spring 168 to engage an inlet flow path seat 170. The spring 168 extends between a relief valve port plug 174 and an annular flange projecting radially outward from the head 166. When the fluid pressure in the outlet flow path 108 exceeds that sufficient to displace the valve member 162 against the pressure of the spring 168, the valve member 162 moves to align the pressure relief outlet 172 with the inlet flow path 106.

[0031] Further reference Figure 6 shows additional details related to the start injection fuel check valve 130. The start injection fuel check valve 130 may be located at the junction of the outlet flow path 108 of the low-pressure pump 104 and the start injection fuel flow path 112. In an embodiment, the start injection fuel check valve 130 is located downstream of the start injection fuel flow path 112 and upstream of an outlet 178 on the pump housing 180 of the low-pressure pump 104. In an embodiment, the start injection fuel check valve 130 is mounted on the housing 180 of the low-pressure pump 104 and extends into the outlet flow path 108.

[0032] The start injection fuel check valve 130 includes a base 132 that engages the housing 180 of the low-pressure pump 104. A head 136 extends outwardly from one side of the base 132. The head 136 may include a drive tool recess to facilitate installation and removal of the start injection fuel check valve 130 from the housing 180. A shaft 134 extends from the base 132 in a direction opposite to the head 136. The head 136 projects radially outward from the base 132, and the base 132 projects radially outward from the shaft 134.

[0033] The shaft 134 extends from the base 132 to an end 144 of the shaft 134. The end 134 includes a valve seat 138. In an embodiment, the valve seat 138 is a concave recess in the end 134. In an embodiment, the concave recess is spherical to complement the spherical shape of the ball-type valve member 140. Other embodiments contemplate other shapes for the valve seat 138 and / or the valve member 140. For example, disk-shaped, cylindrical, or flat-shaped valve seats and / or valve members are also contemplated.

[0034] In an embodiment, the outlet flow path 108 includes a cross-sectional dimension W1 that extends transversely to the fluid flowing through the outlet flow path 108. The shaft 134 includes a length L1 from the base 132 to the end 144 that is configured such that the shaft 134 has a length L2 that protrudes into the outlet flow path 108. In an embodiment, the length L2 is at least one-third of the cross-sectional dimension W1 such that the valve member 140 moves from Figure 5 the closed position against the start injection fuel path seat 146 to Figure 4 the open position engaging the valve seat 138 with a minimized travel distance. In an embodiment, the length L2 is even less than half of the cross-sectional dimension W1 in order to minimize the travel distance of the valve member 140 from the start injection fuel path seat 146 to the valve seat 138.

[0035] The spring 142 has a length L3 from the base 132 to the valve member 140 that biases the valve member 140 into contact with the start injection fuel path seat 146 in the closed position, as Figures 5 - 6 shown. The length L1 of the shaft 134 supports more than half of the length L3 of the spring 142, thereby providing stability to the spring 142 during pressure fluctuations in the outlet flow path. Since the shaft 134 intrudes into the outlet flow path 108, the shaft 134 may include one or more holes 158 that extend transversely to the length of the shaft 134 and in the direction of the outlet flow path 108 to allow fuel to flow through the shaft 134.

[0036] The start injection check valve 130 reduces the allowable displacement of the valve member 140 between the start injection fuel path seat 146 and the valve seat 138. The shaft 134 of the start injection check valve 130 extends into the outlet flow path 108 to guide the spring 142 that holds the valve member 140. The size and mass of the valve member 140 will determine the flow rate and opening pressure required for a given design of the fuel system 100. The start injection check valve 130 allows high flow / pressure fluctuations at the junction of the outlet flow path and the start injection flow path 112 without compromising durability due to, for example, undesired movement between the spring 142 and the valve member 140 due to insufficient pressure to seat the valve member 140, special spring materials or coatings, particle blockage, etc. The start injection check valve 130 simplifies the spring by restricting the function of the spring 142 to holding the valve member 142 against the start injection fuel path seat 146.

[0037] During the start-up priming fuel cycle using the electric lift pump 115, the gear assembly 150 does not rotate. The electric lift pump 115 operates for a predetermined period of time and primes the entire fuel circuit of the fuel system 100. Since the gear assembly 150 is not rotating, the start-up priming check valve 130 unseats from the start-up priming path seat 146 so that fuel from the electric lift pump 115 flows through the low-pressure pump 104. The unseating of the start-up priming check valve 130 allows fuel flow to bypass the more restrictive pumping flow path 148 that includes the gear assembly 150. As discussed above, the travel of the valve member 140 to the valve seat 138 is limited by the length of the shaft 134 such that the valve member 140 cannot disengage from the spring 142 and fall into the outlet flow path 108. For example, as Figure 4 shown, even in the open position, the valve member 140 remains at least partially within the start-up priming flow path 112. The length of the shaft 134 also supports and guides a majority of the length of the spring 142, resists buckling of the spring 142, and allows the use of a low-stiffness spring.

[0038] When the gear assembly 150 of the low-pressure pump 104 begins to rotate, the electric lift pump 115 is shut off, and the low-pressure pump 104 begins to transfer fuel from the fuel source 114 to the high-pressure pump 116. The inlet pressure of the low-pressure pump 104 will become a vacuum, and due to the vacuum at the inlet flow path 106 and the pressure at the outlet flow path 108, the valve member 140 seats against the start-up priming path seat 146. Fuel flow now passes through the pumping flow path 148 and the gear assembly 150 to the outlet flow path 108. As discussed above, the shaft 134 extends into the outlet flow path 108, partially restricting the fuel flow out of the gear assembly 150. One or more holes 158 in the shaft 134 create a flow path for the fuel, reducing the flow restriction caused by the shaft 134. Additionally, the shaft 134 supports a majority of the length of the spring 142 to protect the spring 142 from pulsating flow caused by the gear meshing of the gear assembly 150.

[0039] A further written description of several example aspects of the present disclosure and their implementations will now be provided. It should be understood that any combination of one or more of the implementations is contemplated.

[0040] According to one aspect of the present disclosure, a fuel system for an internal combustion engine is provided. The fuel system includes a low-pressure pump having an inlet flow path for receiving fuel from a fuel source and an outlet flow path for outputting pressurized fuel. The low-pressure pump includes a start injection fuel flow path extending from the inlet flow path to the outlet flow path, and the start injection fuel flow path includes a start injection fuel path seat. The low-pressure pump further includes a pumping flow path connected to the inlet flow path downstream of the start injection fuel flow path. The pumping flow path is further connected to the outlet flow path upstream of the start injection fuel flow path. The fuel system also includes a start injection check valve connecting the start injection fuel flow path and the outlet flow path. The start injection check valve includes a valve member and a valve seat in the outlet flow path. The valve member engages with the start injection fuel path seat to close the start injection fuel flow path, and is displaced to engage with the valve seat in the outlet flow path to open the start injection fuel flow path.

[0041] In an embodiment, the fuel system includes a high-pressure pump downstream of the low-pressure pump and a fuel tank upstream of the low-pressure pump.

[0042] In a further embodiment, the fuel system includes an electric lift pump in the fuel tank. The electric lift pump is operable to supply pressurized fuel to the low-pressure pump during start injection of the fuel system to displace the valve member from the start injection seat to the valve seat.

[0043] In an embodiment, the low-pressure pump includes a gear assembly in the pumping flow path. The gear assembly is driven by a camshaft to pump fluid from the inlet flow path to the outlet flow path, and the camshaft is driven by an output shaft of the internal combustion engine.

[0044] In a further embodiment, the gear assembly includes a first gear and a second gear meshing with the first gear.

[0045] In an embodiment, the start injection check valve includes a base engaged with the low-pressure pump and a shaft extending from the base into the outlet flow path. The valve seat is located at an end of the shaft. A spring surrounds the shaft, and the spring engages with the valve member to bias the valve member towards the start injection fuel path seat.

[0046] In a further embodiment, the outlet flow path includes a cross-sectional width, and the shaft extends across at least one-third of the cross-sectional width of the outlet flow path.

[0047] In yet a further embodiment, the shaft extends across at least half of the cross-sectional width of the outlet flow path.

[0048] In a further embodiment, the valve member is a ball valve and the valve seat is a recess in the end of the shaft.

[0049] In a further embodiment, a spring extends from the base through the outlet flow path to bias the valve member against the start injection fuel path seat.

[0050] In yet a further embodiment, the shaft is located in the outlet flow path and supports the spring in the outlet flow path.

[0051] In a further embodiment, the shaft includes at least one hole that extends transversely through the shaft to facilitate the flow of fuel through the shaft in the outlet flow path.

[0052] In an embodiment, the low-pressure pump includes a pressure relief valve that is in fluid communication with the outlet flow path. The pressure relief valve is configured to open in response to the fluid pressure in the outlet flow path exceeding a pressure threshold to fluidly connect the outlet flow path to the inlet flow path.

[0053] In another aspect of the present disclosure, a start injection fuel check valve for a low-pressure pump is provided. The start injection fuel check valve includes a base that can be engaged with the low-pressure pump and an elongate shaft that extends from the base. The elongate shaft includes a valve seat at an end of the shaft opposite the base. The start injection fuel check valve further includes a spring that is positioned around the shaft and a valve member that is supported by the spring. The spring biases the valve member away from the valve seat to a first position and compresses when the valve member moves toward engagement with the valve seat. The shaft supports most of the length of the spring in the first position.

[0054] In an embodiment, the valve seat is a recess in the end of the shaft.

[0055] In an embodiment, the valve member is a ball valve that is received in the recess when the valve member engages the valve seat.

[0056] In an embodiment, the shaft includes a length that extends from the base to the end of the shaft. The shaft includes at least one hole that extends transversely to the length through the shaft.

[0057] In a further embodiment, the shaft includes a plurality of holes that extend transversely through the shaft to the length of the shaft.

[0058] In an embodiment, the start injection fuel check valve includes a head that extends from the base opposite the shaft. The base projects radially outward from the shaft and the head projects radially outward from the base.

[0059] According to another aspect of the present disclosure, a low-pressure pump for a fuel system of an internal combustion engine is provided. The low-pressure pump includes a housing and a start injection fuel check valve coupled to the housing. The housing includes an inlet flow path for receiving fuel from a fuel source and an outlet flow path for outputting pressurized fuel. The housing further includes a start injection fuel flow path extending from the inlet flow path to the outlet flow path. The start injection fuel flow path includes a start injection fuel path seat. The housing further includes a pumping flow path connected to the inlet flow path downstream of the start injection fuel flow path. The pumping flow path is further connected to the outlet flow path upstream of the start injection fuel flow path. The start injection fuel check valve includes a shaft extending into a valve seat in the outlet flow path, a spring surrounding the shaft, and a valve member supported by the spring. The spring biases the valve member to engage the start injection fuel path seat to close the start injection fuel flow path, and the valve member is displaced to compress the spring and engage the valve seat in the outlet flow path to open the start injection fuel flow path.

[0060] In an embodiment, in the open position, the valve partially resides in the outlet flow path and partially resides in the start injection fuel flow path when engaged to the valve seat.

[0061] While the illustrative embodiments of the present disclosure have been described in detail in the drawings and the foregoing description, it is to be considered as illustrative rather than restrictive in nature. It should be understood that only certain exemplary embodiments have been shown and described, and all changes and modifications that fall within the spirit of the invention claimed are desired to be protected. It should be understood that while the use of words such as preferred, preferably, preferable or more preferable in the foregoing description indicates that the features so described may be more desirable, they may not be necessary, and embodiments lacking such features are contemplated to be within the scope of the present invention, which is defined by the appended claims. When reading the claims, it is intended that when words such as "a / an", "at least one" or "at least a portion" are used, the claims are not to be limited to only one item unless there is an express contrary statement in the claim. When the language "at least a portion" and / or "a portion" is used, the article may include a portion and / or the whole article unless there is an express contrary statement.

Claims

1. A fuel system for an internal combustion engine, the fuel system comprising: A low-pressure pump having an inlet flow path for receiving fuel from a fuel source, the low-pressure pump having an outlet flow path for outputting pressurized fuel, the low-pressure pump comprising: A start injection fuel flow path extending from the inlet flow path to the outlet flow path, the start injection fuel flow path including a start injection fuel path seat; and A pumping flow path connected to the inlet flow path downstream of the start injection fuel flow path, the pumping flow path further connected to the outlet flow path upstream of the start injection fuel flow path; and A start injection fuel check valve connecting the start injection fuel flow path to the outlet flow path, wherein the start injection fuel check valve includes a valve member and a valve seat in the outlet flow path, wherein the valve member engages the start injection fuel path seat to close the start injection fuel flow path, and is displaced to engage the valve seat in the outlet flow path to open the start injection fuel flow path.

2. The fuel system according to claim 1, further comprising: A high-pressure pump downstream of the low-pressure pump; And A fuel tank upstream of the low-pressure pump.

3. The fuel system according to claim 2, further comprising an electric lift pump in the fuel tank, wherein the electric lift pump is operable to supply pressurized fuel to the low-pressure pump during start injection of the fuel system to displace the valve member from the start injection seat to the valve seat.

4. The fuel system according to claim 1, wherein the low-pressure pump includes a gear assembly in the pumping flow path, the gear assembly being driven by a camshaft to pump fluid from the inlet flow path to the outlet flow path, and the camshaft being driven by an output shaft of the internal combustion engine.

5. The fuel system according to claim 4, wherein the gear assembly includes a first gear and a second gear meshing with the first gear.

6. The fuel system according to claim 1, wherein the start injection fuel check valve includes: A base engaging the low-pressure pump; A shaft extending from the base into the outlet flow path, wherein the valve seat is located at an end of the shaft; and A spring surrounding the shaft, the spring engaging the valve member to bias the valve member towards the start injection fuel path seat.

7. The fuel system according to claim 6, wherein the outlet flow path includes a cross-sectional width, and the shaft extends across at least one-third of the cross-sectional width of the outlet flow path.

8. The fuel system according to claim 7, wherein the shaft extends across at least half of the cross-sectional width of the outlet flow path.

9. The fuel system according to claim 6, wherein the valve member is a ball valve and the valve seat is a recess in the end of the shaft.

10. The fuel system according to claim 6, wherein the spring extends from the base through the outlet flow path to bias the valve member against the starting injection fuel path seat.

11. The fuel system according to claim 10, wherein the shaft is located in the outlet flow path and supports the spring in the outlet flow path.

12. The fuel system according to claim 6, wherein the shaft includes at least one hole that extends transversely through the shaft to facilitate the flow of fuel through the shaft in the outlet flow path.

13. The fuel system according to claim 1, wherein the low-pressure pump includes a pressure relief valve in fluid communication with the outlet flow path, the pressure relief valve being configured to open in response to the fluid pressure in the outlet flow path exceeding a pressure threshold to fluidly connect the outlet flow path to the inlet flow path.

14. A starting injection fuel check valve for a low-pressure pump of a fuel system, the starting injection fuel check valve comprising: A base that can be engaged with the low-pressure pump; An elongated shaft that extends from the base, the elongated shaft including a valve seat at an end of the shaft opposite the base; A spring that is positioned around the shaft; and A valve member that is supported by the spring, the spring biasing the valve member away from the valve seat to a first position and compressing when the valve member moves towards engagement with the valve seat, wherein the shaft supports most of the length of the spring in the first position.

15. The starting injection fuel check valve according to claim 14, wherein: The valve seat is a recess in the end of the shaft; and The valve member is a ball valve that is received in the recess when the valve member engages the valve seat.

16. The starting injection fuel check valve according to claim 14, wherein: The shaft includes a length that extends from the base to the end of the shaft; and The shaft includes at least one hole that extends transversely to the length through the shaft.

17. The starting injection fuel check valve according to claim 16, wherein the shaft includes a plurality of holes that extend transversely to the length of the shaft through the shaft.

18. The starting injection fuel check valve according to claim 14, further comprising a head that extends from the base opposite the shaft, and wherein the base projects radially outward from the shaft and the head projects radially outward from the base.

19. A low-pressure pump for a fuel system of an internal combustion engine, the low-pressure pump comprising: A housing that includes: An inlet flow path for receiving fuel from a fuel source; An outlet flow path for outputting pressurized fuel; A starting injection fuel flow path that extends from the inlet flow path to the outlet flow path, the starting injection fuel flow path including a starting injection fuel path seat; and A pumping flow path that is connected to the inlet flow path downstream of the start-up fuel injection flow path, and the pumping flow path is further connected to the outlet flow path upstream of the start-up fuel injection flow path; A start-up fuel injection check valve that engages with the housing, the start-up fuel injection check valve comprising: A shaft that extends into the outlet flow path to a valve seat in the outlet flow path; A spring that surrounds the shaft; and A valve member that is supported by the spring, wherein the spring biases the valve member to engage with the start-up fuel injection path seat to close the start-up fuel injection flow path, and the valve member is displaced to compress the spring and engage the valve seat in the outlet flow path to open the start-up fuel injection flow path.

20. The low-pressure pump according to claim 19, wherein the valve member partially resides in the outlet flow path and the start-up fuel injection flow path when engaged with the valve seat.

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