Pressure regulating valve for engine fuel system

Abstract

A fuel system for an internal combustion engine includes a low pressure fuel pump and a pressure regulating valve. The pressure regulating valve is located at an inlet to the low pressure fuel pump to regulate fuel pressure and fuel flow in the system.

Description

[0001] Cross - reference to related applications:

[0002] This application claims the benefit of priority and the filing date of U.S. Provisional Application Serial No. 63 / 383,558, filed on November 14, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to internal combustion engines, and more particularly but not exclusively to a pressure regulating valve for a fuel system of the internal combustion engine. Background Art

[0004] Common rail direct fuel injection is commonly used in fuel systems for internal combustion engines, such as diesel engines. A common rail direct fuel system typically 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 equalizes the pressure according to the number of fuel injectors connected, and then the fuel injectors inject the fuel into the engine.

[0005] The low - pressure fuel pump typically includes a pressure regulating valve on the outlet side of the low - pressure pump. The pressure regulating valve can be used to ensure an adequate fuel supply to the inlet of the high - pressure pump. However, current pressure regulating valves can provide excessive fuel recirculation at higher engine speeds, which can result in excessive power consumption, an increase in fuel temperature, and an increase in pressure in the low - pressure pump circuit. Therefore, there is a need for an improvement in the pressure regulating valve for an internal combustion engine fuel system. Summary of the Invention

[0006] The present disclosure includes a pressure regulating valve (PRV) upstream of the inlet of a pump located in a fuel system for an internal combustion engine. In one embodiment, the pump is a lower or low - pressure pump upstream of a higher or high - pressure pump in the fuel system. The pressure regulating valve is operable to regulate the fuel flow from a fuel source to the inlet of the low - pressure pump.

[0007] 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 for receiving fuel from a fuel source. The fuel pump has an outlet for providing pressurized fuel. A bypass flow path extends from the outlet toward the inlet. The fuel system further includes a pressure regulating valve connecting the bypass flow path to the inlet. The pressure regulating valve includes a fuel passage connecting the fuel source to the inlet of the fuel pump and a plunger in the fuel passage. The plunger is displaced by the fuel pressure in the bypass flow path to close the fuel passage in the pressure regulator in response to the fuel pressure in the bypass flow path exceeding a threshold pressure.

[0008] In an embodiment of the present disclosure, a pressure regulating valve for a fuel system pump is provided. The pressure regulating valve includes a plunger and an elongated body extending between a first end and an opposite second end. The elongated body defines a fuel passage, and the plunger is received within the fuel passage. The elongated body includes: an opening located at the first end and configured to receive fuel from a fuel pump bypass flow path; a valve inlet leading to the fuel passage between the first end and the second end, the valve inlet receiving fuel from a fuel source; and a valve outlet located between the first end and the second end, the valve outlet providing fuel from the fuel passage to the fuel system pump. The plunger is movable from a first position toward a second position in response to pressure from fuel in the fuel pump bypass flow path. In the first position, the plunger is positioned within the fuel passage to allow fuel from the fuel source to flow through the valve inlet into the fuel passage and through the valve outlet to the fuel system pump. In the second position, the plunger blocks the valve inlet and impedes fuel flow from the fuel source through the valve inlet.

[0009] This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Additional embodiments, forms, objects, features, advantages, aspects, and benefits will become apparent from the following description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The description herein refers to the accompanying drawings, in which like reference numerals refer to like parts throughout the several views, and in which:

[0011] Figure 1 is a schematic block diagram of an exemplary fuel system for an internal combustion engine including a pressure regulating valve according to an embodiment of the present disclosure.

[0012] Figure 2 is a schematic view showing a pressure reducing valve upstream of the pressure regulating valve.

[0013] Figure 3 is Figure 1 a perspective view of an embodiment of the pressure regulating valve.

[0014] Figure 4 is Figure 3 a longitudinal cross-sectional view of the pressure regulating valve.

[0015] Figure 5 is Figure 3 a perspective view of a plunger received within the pressure regulating valve.

[0016] Figure 6 is Figure 3 a cross-sectional view of the pressure regulating valve showing the plunger in a first position that does not restrict fuel flow.

[0017] Figure 7 is a cross-sectional view of a pressure regulating valve that Figure 3 shows a plunger in an intermediate position that restricts fuel flow.

[0018] Figure 8 is a cross-sectional view of a pressure regulating valve that Figure 3 shows a plunger in a second position that prevents fuel flow. DETAILED DESCRIPTION

[0019] 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, manufacture, and use of the present disclosure, certain exemplary embodiments will now be referred to, including those shown in the figures, and the present disclosure will be described using specific language. However, it should be understood that no limitation of the scope of the invention will thereby result, and the invention includes and protects such changes, modifications, and further applications of the exemplary embodiments that would occur to those skilled in the art.

[0020] Referring to Figures 1 to 8 , a fuel system 100 for an internal combustion engine 102 is shown. In an embodiment of the present disclosure, the fuel system 100 includes a fuel pump 104 having an inlet 106 for receiving fuel from a fuel source 110. The fuel pump 104 has an outlet 108 for providing pressurized fuel to the fuel system 100. The fuel system 100 includes a bypass flow path 112 extending from the outlet 108 toward the inlet 106. The fuel system 100 includes a pressure regulating valve 130 connecting the bypass flow path 112 to the inlet 106. The pressure regulating valve 130 includes a fuel passage 132 fluidly connecting the fuel source 110 to the inlet 106 of the fuel pump 104. The pressure regulating valve 130 further includes a plunger 134 located in the fuel passage 132. The plunger 134 is displaced by the fuel pressure in the bypass flow path 112 to close the fuel passage 132 in the pressure regulating valve 130 in response to the fuel pressure in the bypass flow path 112 exceeding a threshold pressure.

[0021] In an embodiment of the present disclosure, a pressure regulating valve 130 for a fuel pump 104 is shown. The pressure regulating valve 130 includes a plunger 134 and a body 136 extending between a first end 138 and an opposite second end 140. The body 136 defines a fuel passage 132 therein, and the plunger 134 is located in the fuel passage 132. The body 136 includes an opening 142 at the first end 138. The opening 142 is configured to receive fuel from a fuel pump bypass flow path 112. The body 136 includes a valve inlet 144 leading to the fuel passage 132, the valve inlet being configured to receive fuel from a fuel source. The valve inlet 144 is located on a side of the body 136 between the first end 138 and the second end 140. The body 136 includes a valve outlet 146 from the fuel passage 132, the valve outlet being configured to supply fuel from the fuel passage 132 to the fuel pump 104. The valve outlet 146 is located on this side of the body 136 between the first end 138 and the second end 140. The plunger 134 is movable from a first position in the fuel passage 132 toward a second position in the fuel passage 132 in response to pressurized fuel in the fuel pump bypass flow path 112. In the first position, the plunger 134 allows fuel from the fuel source 110 to flow through the valve inlet 144 into the fuel passage 132 and through the valve outlet 146 to the fuel pump 104. In the second position, the plunger 134 is located in the fuel passage 132 to block the valve inlet 144 and impede fuel from flowing from the fuel source 110 into the fuel passage 132.

[0022] Figure 1 The fuel system 100 in is configured to supply fuel 114 from a fuel source 110 to an internal combustion engine 102. The fuel system 100 includes a first or low-pressure pump 104 that pressurizes the fuel and supplies it to an inlet of a second or high-pressure pump 116. The low-pressure pump 104 is located upstream of the high-pressure pump 116. A camshaft 124 may be provided to mechanically drive each of the low-pressure pump 104 and the high-pressure pump 116. The camshaft 124 may be connected to and driven by an output shaft 126 of the engine 102.

[0023] 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 high-pressure fuel system 100 are shown. Other details and components, such as a starting pump, filters, valves, drain pipes, bypasses, piping, venturi devices, etc., are omitted for clarity and / or being irrelevant to the present disclosure.

[0024] The inlet 106 of the low-pressure pump 104 receives fuel from the fuel source 110 through the pressure regulating valve 130. The fuel is pressurized by the fuel pump 104 and supplied to the inlet of the high-pressure pump 116 and reaches the bypass flow path 112. The fuel flow rate into the inlet 106 is controlled by the fuel pressure in the bypass flow path 112 acting on the pressure regulating valve 130, which is located in the flow path from the fuel source 110 to the inlet 106. As used herein, the inlet 106 can be any structure connected to the upstream side of the fuel pump 104, such as a housing inlet for the fuel pump 104 or a fuel line inlet connected to the housing of the fuel pump 104.

[0025] Reference Figures 3 to 5 , further details of the pressure regulating valve 130 are shown. The pressure regulating valve 130 can be located at the inlet 106 of the low-pressure pump 104. In one embodiment, the pressure regulating valve 130 is located upstream of the housing of the low-pressure pump 104. In one embodiment, the pressure regulating valve 130 is integrated with the housing of the low-pressure pump 104.

[0026] The pressure regulating valve 130 includes a body 136 that is elongated and extends between a first end 138 and an opposite second end 140 along a longitudinal axis L. The elongated body 136 defines a fuel passage 132 therein. A plunger 134 is located in the fuel passage 132 and also extends along the longitudinal axis L and is movable along the longitudinal axis L.

[0027] The body 136 includes a cylindrical shape between the first end 138 and the second end 140. Circular sealing rings 150, 152 can be provided around the body 136 to provide a sealed engagement with the corresponding structure in which the body 136 of the fuel system 100 is placed. The second end 140 includes a hexagonal shape 154 or other suitable configuration for engaging a tool. The second end 140 can initially also be open for inserting and assembling the plunger 134 and the biasing member 156 into the fuel passage 132. Thereafter, the opening at the second end 140 can be plugged with a plug ball 158 or other suitable closing device. In the illustrated embodiment, the biasing member 156 is a helical spring, but any suitable biasing member is contemplated.

[0028] The elongated body 136 further includes an opening 142 located at the first end 138. In the illustrated embodiment, the opening 142 is located on the longitudinal axis L and receives fuel from the fuel pump bypass flow path 112. The pressurized fuel provided through the opening 142 acts on the end of the plunger 134 in the fuel passage 132 and displaces the plunger 134 in the fuel passage 132 against the biasing member 156, as further discussed below.

[0029] The body 136 includes a valve inlet 144 that leads to the fuel passage 132. The valve inlet 144 is positioned to receive fuel 114 from the fuel source 110. The valve inlet 144 is located on a side of the body 136 that is between the first end 138 and the second end 140. The body 136 includes a valve outlet 146 from the fuel passage 132 that is configured to provide fuel from the fuel passage 132 to the inlet 106 of the fuel pump 104. The valve outlet 146 is located on a side of the body 136 that is between the first end 138 and the second end 140.

[0030] The plunger 134 extends from a first plunger end 160 to a second plunger end 162. The first plunger end 160 is oriented toward the first end 138 of the body 136. The second plunger end 162 engages a biasing member 156 that biases the first plunger end 160 toward the first end 138 of the body 136. The plunger 134 is thus normally biased such that the first plunger end 160 contacts the inner surface of the body 136 around the opening 142.

[0031] The plunger 134 includes a first end portion 164 that extends from the first plunger end 160, and a second end portion 166 that extends from the second plunger end 162. A neck 168 extends between and connects the first end portion and the second end portion. The neck 168 tapers from the first end portion 164 toward the second end portion 166. In the illustrated embodiment, the neck 168 is trumpet-shaped. Other shapes of the neck 168 are also contemplated, such as frustoconical shapes, stepped shapes, pyramidal shapes, and other tapered shapes.

[0032] The first end portion 164 and the second end portion 166 are shaped cylindrically to complement the inner shape of the fuel passage 132. The second end portion 166 may include a rod 170 that extends axially therefrom. The rod 170 may be configured to engage the biasing member 156 by positioning the rod 170 within the biasing member 156. Other arrangements for coupling the biasing member 156 to the second end portion 166 of the rod are also contemplated.

[0033] Other embodiments contemplate other shapes and / or configurations of the plunger 134. For example, the plunger 134 may include a cylindrical neck located between the end portions 164, 166. In another embodiment, the plunger 134 is spherical or ball-shaped.

[0034] Further reference Figures 6 to 8, the fuel passage 132 includes a first cross-sectional dimension along the interior of the body 136 from a first end 138 to a second end 140. In the illustrated embodiment, the first cross-sectional dimension is constant along the longitudinal axis L. In one embodiment, the cross-section of the fuel passage 132 is not constant along the longitudinal axis L. In one embodiment, each of the first end portion 164 and the second end portion 166 includes a second cross-sectional dimension that substantially corresponds to the first cross-sectional dimension of the passage 132. Thus, the first end portion 164 and the second end portion 166 substantially occupy or fill the fuel passage 132, and the fuel flow around the first end portion 164 and / or the second end portion 166 in the fuel passage 132 is eliminated or substantially reduced.

[0035] In the first position of the plunger 134, the neck 168 is located between the valve inlet 144 and the valve outlet 146, and the fuel passage 132 extends around the neck 168. In the second position of the plunger 134 that occurs due to the fuel pressure in the bypass flow path 112 acting on the first end portion 164, the first end portion 164 of the plunger 134 is located between the valve inlet 144 and the valve outlet 146. When the plunger 134 moves from the first position towards the second position, the tapered shape of the neck 168 provides a gradually decreasing flow around the neck 168 between the valve inlet 144 and the valve outlet 146.

[0036] The plunger 134 is movable from a first position in the fuel passage 132 towards a second position in the fuel passage 132 in response to pressurized fuel in the fuel pump bypass flow path 112. In the first position, the plunger 134 allows fuel from the fuel source 110 to flow through the valve inlet 144 into the fuel passage 132 and through the valve outlet 146 to the fuel pump 104. In the second position, the plunger 134 is located in the fuel passage 132 to block the valve inlet 144 and impede fuel from flowing from the fuel source 110 into the fuel passage 132.

[0037] In the case where the plunger 134 is in the second position to impede fuel flow to the fuel pump 104, the pressure in the bypass flow path 112 can continue to increase. As Figure 2 shown, a pressure relief valve 200 can be provided between the bypass flow path 112 and the upstream side of the pressure regulating valve 130. The pressure relief valve 200 is configured to discharge fuel from the bypass flow path 112 to the upstream side in response to the fuel pressure in the bypass flow path 112 exceeding a second pressure threshold. In one embodiment, the second pressure threshold is greater than the pressure threshold when the plunger 134 is displaced to the second position.

[0038] In one embodiment, the pressure relief valve 200 includes a ball valve 202 having a biasing member 204 that biases the ball valve 202 to a closed position, as shown at 202'. In the open position, the ball valve 202 is displaced to compress the biasing member 204 (such as a spring), and allows fuel to flow back upstream of the pressure regulating valve 130. The discharged fuel flow can return to, for example, the fuel source 110 until the pressure in the bypass flow path 112 is reduced enough to allow the biasing member 204 to close the ball valve 202.

[0039] Other embodiments contemplate other configurations for the pressure relief valve 200. For example, the pressure regulating valve 130 itself can be provided with an exhaust structure to release the pressure in the bypass flow path 112 when the plunger 134 is closed. The ball valve 202 can be replaced with any suitable pressure control valve member. In one embodiment, the pressure relief valve 200 is integrated with the pressure regulating valve 130 into the housing of the low pressure pump 104.

[0040] In one embodiment, the valve inlet 144 and the valve outlet 146 have substantially the same size. In one embodiment, the valve inlet 144 and the valve outlet 146 have the same size. In one embodiment, the valve inlet 144 and the valve outlet 146 have different sizes. In one embodiment, the valve inlet 144 and the valve outlet 146 have the same shape. In one embodiment, the valve inlet 144 and the valve outlet 146 are different shapes.

[0041] In one embodiment, the opening 142 extends along the longitudinal axis L of the elongated body 136. In one embodiment, the valve inlet 144 and the valve outlet 146 extend through the elongated body 136 orthogonally to the longitudinal axis L. In one embodiment, the valve inlet 144 and the valve outlet 146 extend through the elongated body 136 non - orthogonally to the longitudinal axis L. In one embodiment, the valve inlet 144 and the valve outlet 146 are aligned with each other along a second axis A that is orthogonal to the longitudinal axis L. In one embodiment, the valve inlet 144 and the valve outlet 146 are aligned with each other along a second axis A that is not orthogonal to the longitudinal axis L.

[0042] A further written description of several example aspects of the present disclosure and their embodiments will now be provided. It should be understood that any combination of one or more of the embodiments is contemplated.

[0043] According to one aspect of the present disclosure, a fuel system for an internal combustion engine is provided. The fuel system includes a fuel pump having an inlet for receiving fuel from a fuel source and an outlet for providing pressurized fuel. The fuel system further includes a bypass flow path extending from the outlet towards the inlet, and a pressure regulating valve connecting the bypass flow path to the inlet. The pressure regulating valve includes a fuel passage fluidly connecting the fuel source to the inlet of the fuel pump and a plunger in the fuel passage. The plunger is displaced by the fuel pressure in the bypass flow path to close the fuel passage in the pressure regulator in response to the fuel pressure in the bypass flow path exceeding a threshold pressure.

[0044] In one embodiment, the pump is a low-pressure pump and the fuel system includes a high-pressure pump downstream of the low-pressure pump.

[0045] In another embodiment, the fuel system includes a rail connected to the high-pressure pump. The rail distributes the pressurized fuel to a plurality of fuel injectors of the internal combustion engine.

[0046] In yet another embodiment, the low-pressure pump and the high-pressure pump are each driven by a camshaft, and the camshaft is driven by an output shaft of the internal combustion engine.

[0047] In one embodiment, the pressure regulating valve includes an opening connected to the bypass flow path, and the plunger is located between the opening and the fuel passage.

[0048] In one embodiment, the pressure regulating valve includes a valve inlet leading to the fuel passage and a valve outlet leading from the fuel passage. The valve inlet is connected to the fuel source, and the valve outlet is connected to the inlet of the fuel pump.

[0049] In another embodiment, the plunger in the fuel passage is displaced from a first position to a second position by the pressurized fuel in the bypass flow path. In the first position, fuel is allowed to flow through the fuel passage from the valve inlet to the valve outlet, and in the second position, the plunger obstructs the fuel from flowing from the valve inlet to the valve outlet and fluidly disconnects the fuel source from the inlet of the fuel pump.

[0050] In another embodiment, the pressure regulating valve includes an opening in fluid communication with the bypass flow path.

[0051] In another embodiment, the plunger is configured to gradually reduce the fuel flow rate through the fuel passage from the valve inlet to the valve outlet as the plunger is displaced from the first position towards the second position.

[0052] In one embodiment, the fuel system includes a pressure reducing valve between the bypass flow path and the upstream side of the pressure regulating valve. The pressure reducing valve is configured to discharge fuel from the bypass flow path to the upstream side in response to the fuel pressure in the bypass flow path exceeding a second pressure threshold greater than the pressure threshold.

[0053] In another aspect of the present disclosure, a pressure regulating valve for a fuel pump is provided. The pressure regulating valve includes a plunger and a body extending between a first end and an opposite second end. The body defines a fuel passage therein, and the plunger is located in the fuel passage. The body includes an opening at the first end, which is configured to receive fuel from a fuel pump bypass flow path. The body further includes a valve inlet leading to the fuel passage, which is configured to receive fuel from a fuel source. The valve inlet is located on a side of the body between the first end and the second end of the body. The body further includes a valve outlet from the fuel passage, which is configured to supply fuel from the fuel passage to the fuel pump. The valve outlet is located on the side of the body between the first end and the second end of the body. The plunger is movable from a first position in the fuel passage towards a second position in the fuel passage in response to pressurized fuel in the fuel pump bypass flow path. In the first position, the plunger allows fuel from the fuel source to flow through the valve inlet into the fuel passage and through the valve outlet to the fuel pump, and in the second position, the plunger is located in the fuel passage to block the valve inlet and impede fuel from flowing into the fuel passage from the fuel source.

[0054] In one embodiment, the plunger extends from a first plunger end to a second plunger end. The first plunger end is oriented towards the first end of the body, and the second plunger end engages a biasing member. The biasing member is configured to bias the first plunger end towards the first end of the body.

[0055] In another embodiment, the biasing member is a spring located in the body.

[0056] In one embodiment, the plunger includes a first end oriented towards the first end of the body, a second end oriented towards the second end of the body, and a neck connecting the first end to the second end.

[0057] In another embodiment, in the first position, the neck of the plunger is located between the valve inlet and the valve outlet, and the fuel passage extends around the neck. In the second position, a first end portion of the plunger is located between the valve inlet and the valve outlet.

[0058] In another embodiment, the neck tapers from a first end portion towards a second end portion such that as the plunger moves from the first position towards the second position, the flow around the neck between the valve inlet and the valve outlet gradually decreases.

[0059] In another embodiment, the fuel passage includes a first cross-sectional dimension. The first end portion and the second end portion each include a second cross-sectional dimension that substantially corresponds to the first cross-sectional dimension.

[0060] In another embodiment, the opening, the valve inlet, and the valve outlet have substantially the same size.

[0061] In another embodiment, the opening extends along the longitudinal axis of the body, and the valve inlet and the valve outlet extend through the body orthogonally to the longitudinal axis.

[0062] In yet another embodiment, the valve inlet and the valve outlet are aligned with each other along a second axis that is orthogonal to the longitudinal axis.

[0063] Although the illustrative embodiments of the present disclosure have been described in detail in the drawings and the foregoing description, this is considered to be illustrative in nature and not restrictive. 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 protected by the claims are intended to be protected. It should be understood that although the use of words such as "preferred", "preferably", "preferred" or "more preferred" in the above description indicates that the features so described may be more desirable, they may not be essential, 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 using words such as "a / an", "at least one" or "at least a portion", the claims are not intended to be limited to only one item unless there is an express contrary statement in the claim. When using the language "at least a portion" and / or "a portion", 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 fuel pump having an inlet for receiving fuel from a fuel source and an outlet for providing pressurized fuel; A bypass flow path extending from the outlet towards the inlet; And A pressure regulating valve connecting the bypass flow path to the inlet, wherein the pressure regulating valve comprises: A fuel passage fluidly connecting the fuel source to the inlet of the fuel pump; And A plunger located in the fuel passage, wherein the plunger is displaced by the fuel pressure in the bypass flow passage to close the fuel passage in the pressure regulator in response to the fuel pressure in the bypass flow passage exceeding a threshold pressure.

2. The fuel system according to claim 1, wherein the pump is a low-pressure pump, and the fuel system includes a high-pressure pump downstream of the low-pressure pump.

3. The fuel system according to claim 2, the fuel system further comprising a rail connected to the high-pressure pump, the rail for distributing pressurized fuel to a plurality of fuel injectors of the internal combustion engine.

4. The fuel system according to claim 3, wherein the low-pressure pump and the high-pressure pump are each driven by a camshaft, and the camshaft is driven by an output shaft of the internal combustion engine.

5. The fuel system according to claim 1, wherein the pressure regulating valve includes an opening connected to the bypass flow path, and the plunger is located between the opening and the fuel passage.

6. The fuel system according to claim 1, wherein the pressure regulating valve includes: A valve inlet leading to the fuel passage and connected to the fuel source; And A valve outlet from the fuel passage and connected to the inlet of the fuel pump.

7. The fuel system according to claim 6, wherein the plunger in the fuel passage is displaced from a first position to a second position by pressurized fuel in the bypass flow path, and in the first position, fuel is allowed to flow from the valve inlet through the fuel passage to the valve outlet, and in the second position, the plunger obstructs fuel from flowing from the valve inlet to the valve outlet and fluidly disconnects the fuel source from the inlet of the fuel pump.

8. The fuel system according to claim 7, wherein the pressure regulating valve includes an opening in fluid communication with the bypass flow path.

9. The fuel system according to claim 7, wherein the plunger is configured to gradually reduce the fuel flow rate from the valve inlet to the valve outlet through the fuel passage as the plunger is displaced from the first position toward the second position.

10. The fuel system according to claim 1, wherein the fuel system further comprises a pressure reducing valve between the bypass flow path and the upstream side of the pressure regulating valve, wherein the pressure reducing valve is configured to discharge fuel from the bypass flow path to the upstream side in response to the fuel pressure in the bypass flow path exceeding a second pressure threshold greater than the pressure threshold.

11. A pressure regulating valve for a fuel pump, the pressure regulating valve comprising: A plunger; And A body extending between a first end and an opposite second end, the body defining a fuel passage therein, and the plunger being located in the fuel passage, wherein the body comprises: An opening at the first end configured to receive fuel from the fuel pump bypass flow path; A valve inlet leading to the fuel passage and configured to receive fuel from the fuel source, the valve inlet being located on a side of the body between the first end and the second end of the body; A valve outlet from the fuel passage and configured to provide fuel from the fuel passage to the fuel pump, the valve outlet being located on the side of the body between the first end and the second end of the body, wherein: The plunger is movable from a first position in the fuel passage towards a second position in the fuel passage in response to pressurized fuel in the fuel pump bypass flow path; In the first position, the plunger allows fuel from the fuel source to flow through the valve inlet into the fuel passage and through the valve outlet to the fuel pump; and In the second position, the plunger is located in the fuel passage to block the valve inlet and impede fuel from flowing from the fuel source into the fuel passage.

12. The pressure regulating valve according to claim 11, wherein the plunger extends from a first plunger end to a second plunger end, and the first plunger end is oriented towards the first end of the body, and the second plunger end engages a biasing member configured to bias the first plunger end towards the first end of the body.

13. The pressure regulating valve according to claim 12, wherein the biasing member is a spring located in the body.

14. The pressure regulating valve according to claim 11, wherein the plunger comprises: A first end portion oriented towards the first end of the body; A second end portion oriented towards the second end of the body; And A neck connecting the first end portion to the second end portion.

15. The pressure regulating valve according to claim 14, wherein: In the first position, the neck of the plunger is located between the valve inlet and the valve outlet, and the fuel passage extends around the neck; And In the second position, the first end portion of the plunger is located between the valve inlet and the valve outlet.

16. The pressure regulating valve according to claim 14, wherein the neck tapers from the first end portion towards the second end portion such that as the plunger moves from the first position towards the second position, the flow rate around the neck between the valve inlet and the valve outlet gradually decreases.

17. The pressure regulating valve according to claim 14, wherein: The fuel passage includes a first cross-sectional dimension; and The first end portion and the second end portion each include a second cross-sectional dimension substantially corresponding to the first cross-sectional dimension.

18. The pressure regulating valve according to claim 14, wherein the opening, the valve inlet and the valve outlet have substantially the same size.

19. The pressure regulating valve according to claim 14, wherein: The opening extends along a longitudinal axis of the body; and The valve inlet and the valve outlet extend through the body orthogonally to the longitudinal axis.

20. The pressure regulating valve according to claim 19, wherein the valve inlet and the valve outlet are aligned with each other along a second axis orthogonal to the longitudinal axis.

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