Fuel pump
By designing a fuel pump containing an outlet module, the complexity and functional inspection of pressure relief valves and outlet valves in existing fuel pumps is solved, and fault identification and replacement is realized before assembly, reducing waste rate, simplifying structure and improving reliability.
Patent Information
- Application Number
- CN202380085586.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-13
- Filing Date
- 2023-11-23
- Publication Date
- 2025-07-18
AI Technical Summary
In the existing fuel pump design, the integrated pressure relief valve and outlet valve lead to complex structures and difficult to check the functionality later in the assembly, which easily leads to an increase in the scrap rate.
A fuel pump containing an outlet module is designed, which includes an outlet valve body and a pressure relief valve body, which defines the outlet passage and the pressure relief passage respectively, and is fixed to the main body by threaded connections, allowing the valve function to be tested before assembly and reduce production and assembly errors.
It realizes identification and replacement of faulty components before assembly, reduces waste rate, simplifies the main structure, reduces machining requirements, and improves the reliability and efficiency of fuel pumps.
Smart Images
Figure CN120344762A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a fuel pump and an outlet module for a fuel pump. Background Art
[0002] In modern internal combustion engines fueled by gasoline, especially in fuel systems for the automotive market, gasoline direct injection (GDI) is mainly adopted. In these systems, fuel injectors inject fuel directly into the combustion chambers of the internal combustion engines. Generally, fuel from a fuel tank is supplied by a low-pressure fuel pump at a relatively low pressure, and the low-pressure fuel pump is usually an electric fuel pump located within the fuel tank. The low-pressure fuel pump supplies fuel to a high-pressure fuel pump (also known as a GDI pump), which typically includes a pumping plunger reciprocated by a camshaft of the internal combustion engine. During the intake stroke, fuel is drawn into the pumping chamber, and during the subsequent pumping stroke, the pumping plunger further pressurizes the fuel so that it can be supplied to the fuel injector at a high pressure.
[0003] For safe operation, the GDI pump includes a pressure relief passage with an embedded pressure relief valve to avoid any overpressure that may rupture any part of the pump or the high-pressure system behind the pump (fuel rail, pipes, and / or injectors) and to limit the pressure so that the pressure never reaches the maximum opening pressure (MOP) of the injector. To avoid fuel flowing back from the fuel rail into the pumping chamber, the fuel pump also includes an outlet valve, which is arranged in the outlet passage on the high-pressure side of the pumping chamber. Integrating these valves into the fuel pump usually results in a complex design, and various passages may weaken the overall structure of the fuel pump body. Another problem is that when a single faulty part means that the main part of the fuel pump has to be scrapped, the designs of the pressure relief valves and / or outlet valves in the art usually only allow checking the correct functionality at a later stage during the assembly process.
[0004] Object of the Invention
[0005] The object of the present invention is to improve the design of a fuel pump with an integrated pressure relief valve.
[0006] This object is achieved by a fuel pump according to claim 1 and an outlet module according to claim 15. Summary of the Invention
[0007] The present invention relates to a fuel pump. More specifically, the present invention relates to a fuel pump for an internal combustion engine, especially for a fuel pump of a motor vehicle similar to a car. The fuel pump can be configured as a high-pressure pump, which receives fuel from a fuel tank via a low-pressure pump. Then the high-pressure pump increases the pressure of the fuel to generally at least 100 bar, sometimes up to 600 bar or even higher.
[0008] The fuel pump includes a body and an outlet module. The body, which is usually at least partially made of metal to provide the necessary pressure resistance and stability, can be made of a single piece or (usually) several connecting pieces. The body defines an inlet passage, a pumping chamber, and a receiver, all of which are volumes or spaces defined by the body.
[0009] The body defines a pumping chamber in which a pumping plunger is arranged to reciprocate. By the action of the pumping plunger, fuel can be drawn into the pumping chamber during the intake stroke and then can be pressurized and discharged from the pumping chamber during the compression or pumping stroke. Thus, fuel enters the pumping chamber at low pressure and leaves the pumping chamber at high pressure. The pumping plunger can be electrically operated or it can be mechanically connected to an engine, in particular an internal combustion engine to which the fuel pump supplies fuel. For example, the pumping plunger can be connected to the camshaft of the engine. Since the plunger reciprocates along a straight line (i.e., moves back and forth), at least a part of the pumping chamber is cylindrical, the cross-section of which corresponds to the cross-section of the plunger. However, the pumping chamber can include at least one part that is not accessible to the plunger and can have a non-cylindrical shape. It should be understood that the pumping chamber and the passages mentioned below are defined within the housing of the fuel pump.
[0010] The body also defines an inlet passage that at least indirectly connects the low-pressure inlet of the fuel pump to the pumping chamber, and an inlet valve is adapted to selectively allow flow through the inlet passage to the pumping chamber. The low-pressure inlet is adapted to be connected to a low-pressure fuel source, usually a low-pressure pump. Instead of "low-pressure inlet", this can simply be referred to as "inlet", and the term "low-pressure" means that the fuel entering the inlet has not been pressurized by the fuel pump. Of course, the connection to the fuel source can be indirect, for example via a pipe, a hose, etc. The inlet passage establishes a fluid connection or fluid communication directly or indirectly between the inlet and the pumping chamber. In the case of an indirect connection, the inlet passage is connected to another passage that is connected to the inlet. During the intake stroke of the plunger, fuel is drawn into the pumping chamber through the inlet passage. The term "passage" herein and hereinafter refers to any volume that is adapted to accommodate fuel and allow the fuel to be transferred from a starting point (in this case, the low-pressure inlet) to a destination (in this case, the pumping chamber). Such a passage can have various shapes, such as straight, curved, and / or angled, and can be branched or non-branched. The inlet valve is adapted to selectively allow flow through the inlet passage to the pumping chamber. Advantageously, the inlet valve is a normally open valve that can be selectively actuated to a closed position to prevent fuel from flowing in the opposite direction (i.e., back towards the inlet passage). In other words, the pressure on the inlet side of the inlet valve is at least the specified opening pressure greater than the pressure on the pumping chamber side. Additionally, the opening of the inlet valve can be assisted / controlled by an actuator. The inlet valve can be provided on or within the inlet passage, for example, near the inlet, near the pumping chamber, or at some position therebetween. To minimize the dead volume of the pump, it is highly preferred that the inlet valve is provided near the pumping chamber. The inlet valve can be received inside the body or can be considered part of the body.
[0011] In addition, the body defines a receiver that opens distally and extends proximally into the body along an outlet axis such that the receiver communicates with the pumping chamber. The receiver is a recess within the body. More specifically, it is an open recess, i.e., it opens distally (the body has a receiver opening at this distal side). The receiver extends proximally into the body along the outlet axis, with the proximal side being opposite the first side with respect to the outlet axis. More specifically, it extends into the body such that it communicates with the pumping chamber. In other words, the pumping chamber and the receiver are directly or indirectly connected.
[0012] The outlet module is at least partially received within the receiver and is connected to the body in a fuel-tight manner.
[0013] The outlet module includes an outlet passage that at least indirectly connects the pumping chamber to a high-pressure outlet of the fuel pump. The outlet passage is directly or indirectly connected to the pumping chamber and is directly or indirectly connected to the high-pressure outlet. Instead of "high-pressure outlet", this can simply be referred to as "outlet", and the term "high-pressure" indicates that the fuel leaving the outlet has been pressurized by the fuel pump. In the assembled state, the outlet can be connected to a fuel rail, which in turn is connected to a plurality of fuel injectors. During the pumping stroke, fuel is pressurized in the pumping chamber and then discharged from the pumping chamber through the outlet passage.
[0014] In addition, the outlet module includes an outlet valve that is adapted to selectively allow flow through the outlet passage to the outlet. The outlet valve is typically a one-way valve (check valve type) that prevents fuel from flowing in the opposite direction (i.e., towards the pumping chamber). Moreover, the outlet valve may only allow flow towards the outlet if a certain opening pressure is exceeded. The outlet valve can be disposed within the outlet passage, e.g., near the outlet, near the pumping chamber, or disposed therebetween. To minimize the dead volume of the pump, it is highly preferred that the outlet valve is disposed near the pumping chamber.
[0015] The outlet module further includes a pressure relief passage that at least indirectly connects the outlet passage downstream of the outlet valve to the pumping chamber. The pressure relief passage (directly or indirectly) originates from the outlet passage downstream of the outlet valve and (directly or indirectly) leads to the pumping chamber. Thus, fuel can be released from the outlet passage to the pumping chamber through the pressure relief passage. The function of the pressure relief passage is to prevent excessive overpressure in the outlet passage and / or in the fuel rail, for example, connected to the outlet passage.
[0016] In addition, the outlet module includes a pressure relief valve that is adapted to selectively allow flow through a pressure relief passage to the pumping chamber. The pressure relief valve is adapted to selectively allow flow to be directed through the pressure relief passage toward the pumping chamber. More specifically, the pressure relief valve is a one-way valve that prevents fuel from flowing in the opposite direction (i.e., toward the outlet passage). Moreover, the pressure relief valve only allows fuel to flow toward the pumping chamber if a certain opening pressure is exceeded. In other words, if the pressure differential between the outlet passage and the pumping chamber is high enough, the pressure relief valve opens to release fuel from the outlet passage through the pressure relief passage. The pressure relief valve may be disposed inside the pressure relief passage, for example, near the outlet passage, near the pumping chamber, or at some location in between.
[0017] The outlet module includes an outlet passage, a pressure relief passage, an outlet valve, and a pressure relief valve. In other words, the outlet passage, the pressure relief passage, and the corresponding valve mechanisms are combined in the outlet module. The outlet module is in turn received entirely or at least partially within a receiver. It should be understood that the design of the outlet module and its position within the receiver are adapted such that the outlet passage and the pressure relief passage can communicate with the pumping chamber as described above. To prevent any fuel from leaking through the receiver, the outlet module is connected to the body in a fuel-tight manner.
[0018] According to the present invention, the outlet module includes an outlet valve body and a pressure relief valve body. The outlet valve body at least partially defines an outlet passage and at least partially receives an outlet valve. The pressure relief valve body at least partially defines a pressure relief passage and at least partially receives a pressure relief valve, wherein the pressure relief valve body is at least partially received in an outlet valve cavity of the outlet valve body. The outlet valve body and the pressure relief valve body are separately manufactured valve bodies. Each of these bodies is typically made of a single piece. They are typically made of a metal such as stainless steel. Generally speaking, the terms "outlet valve body" and "pressure relief valve body" are used for distinction and should not be construed in any limiting way. However, since the outlet valve body at least partially receives the outlet valve, the outlet valve body is associated therewith. At least a part and / or a portion of the outlet valve is received in the outlet valve body, that is, the outlet valve is disposed in the outlet valve body. Optionally, the entire outlet valve can be received in the outlet valve body. In other embodiments, the outlet valve body or a part thereof can also form a part of the outlet valve. The outlet valve body can form a housing for at least some elements of the outlet valve. Typically, the outlet valve body is at least partially disposed within a receiver. In addition, the outlet valve body at least partially defines the outlet passage. In some embodiments, a part of the outlet passage can be defined by a different element. At least a part of the outlet passage can be a cavity or recess inside the outlet valve body. At least a part and / or a portion of the pressure relief valve is received in the pressure relief valve body, that is, it is disposed therein. Optionally, the entire pressure relief valve can be received in the pressure relief valve body. In other embodiments, the pressure relief valve body or a part thereof forms a part of the pressure relief valve. The pressure relief valve body can form a housing for at least some elements of the pressure relief valve. The pressure relief valve body and the pressure relief valve may together form a pressure relief valve module or a pressure relief valve assembly. The pressure relief valve body at least partially defines the pressure relief passage. In some embodiments, a part of the outlet passage can be defined by a different element, such as by the outlet valve body. At least a part of the pressure relief passage can be a cavity or recess inside the pressure relief valve body.
[0019] The pressure relief valve body is at least partially received in the outlet valve cavity of the outlet valve body. Similarly, the term "outlet valve cavity" should not be construed as meaning that the outlet valve must be received within this cavity, although this is possible. The pressure relief valve body is fully or partially disposed within the outlet valve cavity. During assembly, it is at least partially inserted into this cavity. In some embodiments, the above-mentioned pressure relief valve module can be pre-assembled and then inserted into the outlet valve cavity.
[0020] The design of the present invention allows for the integration of the outlet and pressure relief functions in a single outlet module, which can be produced and assembled separately from the body. The proper functioning of the outlet module, in particular the functions of the outlet valve and the pressure relief valve, can be tested before the outlet module is inserted into the receiver. Thus, production errors or assembly errors can be identified before the final assembly of the fuel pump, which greatly helps to reduce the scrap rate. In the worst case, only the faulty outlet module needs to be replaced. Furthermore, it is even possible to replace only a part of the outlet module, thus further reducing the scrap rate. For example, only the pressure relief valve, the pressure relief valve body, or the entire pressure relief valve module can be replaced. It is also conceivable that the pressure relief valve module is tested before being inserted into the outlet valve cavity. Moreover, integrating the pressure relief passage into the outlet module reduces the need for machining operations on the body. In fuel pumps known in the art, the pressure relief passage typically represents a structural weakness of the body. This weakness is eliminated by the design of the present invention. Integrating the pressure relief passage into the outlet module generally allows for a design that does not weaken the structure of the outlet module in a comparable manner.
[0021] According to a preferred design, the outlet module includes an external thread that engages an internal thread of the body inside the receiver, and the internal thread and the external thread are arranged concentrically around the outlet axis. During assembly, the outlet module is screwed into the receiver when the internal thread and the external thread engage. Since these threads are concentric with respect to the outlet axis, a considerable axial force (in the direction of the outlet axis) can be applied between the body and the outlet module. This axial force can be used to provide a fuel seal between the bodies of the outlet module. For example, a screw connection is advantageous compared to a welded connection that may cause thermal stress and lead to deformation of the body and / or the outlet module.
[0022] Specifically, the outlet module may include a first sealing portion that engages a second sealing portion of the body inside the receiver. Preferably, at least one of the sealing portions includes an annular cutting edge element that cuts into the other sealing portion to form a cutting edge seal. In this embodiment, the outlet module and the body include corresponding sealing portions that engage directly with each other to provide a fuel seal. One of the sealing portions includes an annular cutting edge element, which typically has a sharp wedge-shaped or blade-like profile. The cutting edge element is annular and preferably concentric around the outlet axis. In combination with the above embodiments, this can be particularly advantageous where the outlet module is screwed into the receiver. Through the screwing action between the first thread and the second thread, the cutting edge element on one sealing portion rotates around the outlet axis relative to the other sealing portion while it is also axially pressed against the other sealing portion. The hardness of the cutting edge element is sufficient for it to cut into the other sealing portion, thus providing a cutting edge seal. Preferably, the cutting edge element axially cuts into the other sealing portion. Such seals are known to be extremely reliable and resistant to high pressures.
[0023] In an embodiment, the outlet valve body may be directly connected to the body. For example, the outlet valve body may include external threads. However, according to a preferred embodiment, the outlet module includes an outlet fitting, the outlet valve body is at least partially received in the outlet fitting and the outlet fitting is connected to the body. In this case, the connection of the outlet module to the body is established at least partially or even only via the outlet fitting. When the pressure relief valve body is at least partially received inside the outlet valve body, the outlet valve body is at least partially received inside the outlet fitting. Thus, the outlet module has a nested structure. Preferably, the outlet fitting includes a proximal opening on the proximal side, through which the outlet valve body is inserted during assembly. Generally, the outlet fitting is at least partially received in a receiver. Very preferably, the outlet fitting includes the above-mentioned external threads. Further, it preferably includes the above-mentioned first sealing portion.
[0024] The connection between the pressure relief valve body and the outlet valve body can be established in various ways. For example, it can be established by fusion welding or brazing via cooperating threads that engage with each other. However, the pressure relief valve body is preferably press-fitted into the outlet valve body. This option provides a fluid-tight connection while ensuring a pressure-resistant mechanical connection, avoiding welding operations that may cause deformation or thermal stress, for example. To provide a particularly reliable connection, the pressure relief valve body and the outlet valve body may include corresponding stepped surfaces that cooperate to provide a press fit. Specifically, the pressure relief valve body may include a first proximal press-fit surface and a first distal press-fit surface, the first proximal press-fit surface engages the second proximal press-fit surface of the outlet valve body, the first distal press-fit surface engages the second distal press-fit surface of the outlet valve surface and radially protrudes relative to the first proximal press-fit surface. It should be understood that the first (or second corresponding) proximal press-fit surface is disposed proximally, i.e., towards the proximal side, relative to the first (or second corresponding) distal press-fit surface. Each of the above-mentioned press-fit surfaces is generally parallel to the outlet axis or inclined less than 2° or less than 1° relative to the outlet axis.
[0025] A particularly preferred embodiment provides that at least one of the outlet valve body, the pressure relief valve body, and the outlet fitting is made of a single piece. Preferably, each of these three elements is made of a single piece. In other words, a single piece (of metal) is used for the corresponding element, which typically undergoes various machining operations, for example, to provide an outlet valve cavity, external threads (if any), or other features. However, at least some features may be defined by an initial casting process. The one-piece design facilitates the assembly of the outlet module and increases the structural stability of the individual elements.
[0026] Also preferably, the outlet valve body is press-fitted into the outlet fitting. Again, this enables a fluid-tight connection to be achieved while avoiding deformation or thermal stress. To provide a particularly reliable connection, the outlet valve body and the outlet fitting may include corresponding stepped surfaces. Specifically, the outlet valve body may include a third distal press-fit surface and a third proximal press-fit surface, the third distal press-fit surface engaging a fourth distal press-fit surface of the outlet fitting, and the third proximal press-fit surface engaging a fourth proximal press-fit surface of the outlet fitting and radially protruding relative to the third distal press-fit surface. It should be understood that the third (or fourth corresponding) distal press-fit surface is disposed distally with respect to the third (or fourth corresponding) proximal press-fit surface, i.e., towards the distal side. Each of the above press-fit surfaces is generally parallel to the outlet axis or inclined less than 2° or less than 1° with respect to the outlet axis.
[0027] Preferably, at least two pairs of mating surfaces are used to effect at least one press-fit connection, the pairs of surfaces being axially and radially offset relative to each other. This may relate to a press-fit connection between the pressure relief valve body and the outlet valve body. Alternatively or additionally, it may relate to a press-fit connection between the outlet valve body and the outlet fitting. If one pair of surfaces is offset radially and axially from another pair of surfaces, the reliability and tightness of the connection can be enhanced. At least in some embodiments, the corresponding combination of two pairs of offset surfaces may also be referred to as a stepped press-fit structure.
[0028] As described above, the pressure relief valve body may form a housing for a pressure relief valve. According to one embodiment, the pressure relief valve body includes a pressure relief valve cavity having a first distal insertion opening at the distal side, through which the pressure relief valve is at least partially inserted into the pressure relief valve cavity during assembly. In this context, "partially" means the possibility that the pressure relief valve is not fully inserted into the pressure relief valve cavity, and the possibility that a part of the pressure relief valve may be formed by the pressure relief valve body itself. The first distal insertion opening is designed to allow the pressure relief valve (or a part thereof) to be inserted into the outlet valve body. It is disposed distally, which means that when the pressure relief valve is inserted, it moves towards the proximal side. If the pressure relief valve typically includes a number of components, these components may be pre-assembled outside the pressure relief valve body before insertion. Generally, the pressure relief valve is inserted into the pressure relief valve cavity before the pressure relief valve body is inserted into the outlet valve cavity. However, this is not necessary for this embodiment.
[0029] Preferably, the pressure relief valve includes a first valve seat member, a first valve member, and a first spring member for biasing the first valve member against the first valve seat member. The first valve member and the first spring member are disposed in the pressure relief valve cavity, and the first valve seat member is press-fitted into the pressure relief valve cavity. The first valve member and the first valve seat member cooperate to provide a valve mechanism, where the first valve seat member represents the fixed part of the pressure relief valve, and the first valve member represents the movable part. The first spring member acts directly or indirectly between the first valve seat member and the first valve member. By the action of the first spring member, the first valve member is biased against the first valve seat member to the closed position of the pressure relief valve. Therefore, the force acting on the first valve member due to the pressure difference must overcome the force of the first spring member to move the first valve member to the open position, thereby opening the pressure relief valve. The first valve member and the first spring member are received in the pressure relief valve cavity, whereby they are encapsulated in the pressure relief valve body. The first valve seat member is press-fitted into the pressure relief valve cavity, thereby providing a firm and fluid-tight connection while avoiding welding operations that may cause deformation or thermal stress, for example.
[0030] In an embodiment, the first valve member is at least mostly disposed proximal to the first valve seat member and engages the first valve seat member proximally in the closed position of the pressure relief valve, and the first spring member is disposed proximal to the first valve seat member and engages a first abutment surface of the pressure relief valve body. In this embodiment, the first valve seat member partially closes the pressure relief valve cavity distally and represents an abutment for the first valve member distally. The first spring member can engage the first valve member proximally. Distally, the first spring member abuts against a first abutment surface that is part of the pressure relief valve body. Effectively, the movable parts (the first valve member and the first spring member) of the pressure relief valve are interposed between the first abutment surface and the first valve seat member. Generally, the first valve member is entirely disposed proximal to the first valve seat member, but a small portion of the first valve member can, for example, protrude into a through-hole of the first valve seat member, which allows fuel to flow through the pressure relief valve in its open state.
[0031] The outlet valve body can include a second distal insertion opening on the distal side, through which the outlet valve and the pressure relief valve body are at least partially inserted into the outlet valve cavity during assembly. The second distal insertion opening is in communication with (or can be regarded as part of) the outlet valve cavity. It is designed to allow the pressure relief valve body (or the pressure relief valve module) to be inserted into the outlet valve body. It is provided on the distal side, where the outlet valve and the pressure relief valve body can be inserted from the distal side and moved toward the proximal side. As described above, the pressure relief valve body can be pre-assembled with the pressure relief valve to form a pressure relief valve module, and then the pressure relief valve module can be inserted through the second distal insertion opening. Preferably, the pressure relief valve body is inserted after the outlet valve. Therefore, in the assembled state, the pressure relief valve body is disposed distally of the outlet valve.
[0032] Preferably, the outlet valve includes a second valve seat member, a second valve member, and a second spring member for biasing the second valve member against the second valve seat member. Again, the second valve seat member represents the fixed part of the outlet valve, and the second valve member represents the movable part. The second spring member acts directly or indirectly between the second valve seat member and the second valve member, thereby biasing the second valve member against the second valve seat member to the closed position of the outlet valve. Therefore, the force acting on the second valve member according to the pressure difference must overcome the force of the second spring member to move the second valve member to the open position, thereby opening the outlet valve. Preferably, the second spring member engages a second adjacent surface of the pressure relief valve body. In other words, the second spring member abuts against the second adjacent surface, which is part of the pressure relief valve body. This is beneficial because the pressure relief valve body not only has functions related to the pressure relief passage and the pressure relief valve, but also has functions related to the outlet valve. During assembly, the second valve member and the second spring member can be inserted into the outlet valve cavity, and then the pressure relief valve body is inserted to provide an abutment for the second spring member.
[0033] The second valve seat member can be made as a special element that is connected to the outlet valve body, for example, by a press fit. The preferred embodiment provides that the outlet valve body forms the second valve seat member. This reduces the number of elements and facilitates the assembly process. The second valve seat member can be a radially inwardly projecting flange portion of the outlet valve body. It should be understood that by inserting the movable part of the outlet valve (i.e., the second valve member and the second spring member) from one side (usually the distal side), the movable part is then at least partially closed or blocked by the inserted pressure relief valve body, making this embodiment possible.
[0034] In an embodiment, the outlet passage includes a proximal portion, a distal portion, and a plurality of intermediate portions connecting the proximal portion and the distal portion, where at least a part of the outlet valve is received in the proximal portion. The outlet axis traverses the proximal portion and the distal portion, and the intermediate portions are offset from the outlet axis. Generally, the proximal portion is the farthest from the exterior of the body. The proximal portion may be disposed adjacent to the inlet passage. The outlet valve is at least partially received in the proximal portion. The distal portion is generally disposed farthest from the inlet passage and closest to the outlet or even includes the outlet. In some embodiments, the pressure relief valve body may be at least partially received in the distal portion. The proximal portion and the distal portion are connected by a plurality of intermediate portions, for example, between two and eight, preferably between three and six intermediate portions. When the outlet axis traverses the proximal portion and the distal portion, the intermediate portions are disposed offset from the outlet axis, which can be said to be radially offset from the outlet axis. This can facilitate a compact design of the outlet module because the offset arrangement of the intermediate portions allows other elements to be disposed near or on the outlet axis. In particular, the intermediate portions may be disposed radially outside the outlet valve cavity, at an axial position that partially overlaps with the axial position of the pressure relief valve body. It can be said that the intermediate portions bypass the pressure relief valve body. It is even possible that the axial position of the proximal portion and / or the distal portion overlaps with the axial position of the intermediate portions, where the intermediate portions are disposed radially outside the proximal portion and / or the distal portion. According to one embodiment, the intermediate portions extend parallel to the outlet axis. This is beneficial for manufacturing the outlet valve body because the intermediate portions can be drilled, for example, by a parallel drilling operation.
[0035] The pressure relief passage may include: a valve portion that is adjacent to the pressure relief valve inside the pressure relief valve cavity; at least one first lateral portion that is connected to the valve portion and traverses the pressure relief valve body to its exterior; and at least one second lateral portion that communicates with the at least one first lateral portion, traverses the outlet valve body to its exterior and communicates with the pumping chamber. The valve portion is generally disposed near the outlet axis and may be symmetric therewith. It is arranged adjacent to the pressure relief valve, and the pressure relief valve generally communicates directly with the valve portion. It is disposed inside the pressure relief valve cavity, i.e., it is part of the pressure relief valve cavity. The at least one first lateral portion traverses the pressure relief valve body and generally extends radially outward from the valve portion. There may be a plurality of first lateral portions that diverge / separate from the valve portion and constitute separate connections between the main portion and the exterior of the pressure relief valve body. They may be symmetrically arranged with respect to the outlet axis. The at least one second lateral portion traverses the outlet valve body and generally extends radially outward from the outlet valve cavity. There may be a plurality of second lateral portions. They may be symmetrically arranged with respect to the outlet axis. One second lateral portion may be tangentially and axially aligned with one first lateral portion. In some embodiments, the axial position of the second lateral portion may overlap with the axial position of the intermediate portion. In this case, the different portions are tangentially offset from each other to avoid any interference.
[0036] In an embodiment, at least one of the outlet valve, the pressure relief valve, and the outlet passage is at least mostly symmetric with respect to the outlet axis. "At least mostly symmetric" means that some (minor) components may not be symmetric, but the overall configuration is symmetric. The symmetric design can facilitate the production and assembly of the outlet module. Moreover, it can help optimize the fuel flow through the outlet module. With respect to the pressure relief valve, preferably, the first valve member, the first valve seat member, and the first spring member are each symmetric with respect to the outlet axis. The same applies to the second valve member, the second valve seat member, and the second spring member of the outlet valve. In this case, if the spring axis of the helical spring coincides with the outlet axis, the helical spring is considered symmetric with respect to the outlet axis. If the outlet passage has a proximal portion, a distal portion, and an intermediate portion, the intermediate portion may be disposed on a circle concentric with the outlet axis and evenly spaced along the tangential direction.
[0037] The present invention also relates to an outlet module for a fuel pump, which includes a body that defines:
[0038] - a pumping chamber having a pumping plunger arranged to reciprocate within the pumping chamber;
[0039] - an inlet passage that at least indirectly connects the low-pressure inlet of the fuel pump to the pumping chamber, and an inlet valve adapted to selectively enable flow through the inlet passage to the pumping chamber; and
[0040] - A receiver that faces a distal opening and extends proximally along an outlet axis into the body such that the receiver communicates with the pumping chamber.
[0041] The outlet module is adapted to be at least partially received in the receiver, is connected to the body in a fuel-sealed manner, and includes:
[0042] - An outlet passage that at least indirectly connects the pumping chamber to the high-pressure outlet of the fuel pump,
[0043] - An outlet valve that is adapted to selectively enable flow through the outlet passage to the outlet,
[0044] - A pressure relief passage that at least indirectly connects the outlet passage downstream of the outlet valve to the pumping chamber, and
[0045] - A pressure relief valve that is adapted to selectively enable flow through the pressure relief passage to the pumping chamber.
[0046] According to the present invention, the outlet module includes an outlet valve body and a pressure relief valve body. The outlet valve body at least partially defines the outlet passage and at least partially receives the outlet valve. The pressure relief valve body at least partially defines the pressure relief passage and at least partially receives the pressure relief valve, wherein the pressure relief valve body is at least partially received in the outlet valve cavity of the outlet valve body. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] The present invention will now be described by way of example with reference to the accompanying drawings, in which:
[0048] Figure 1 : is a cross-sectional view of the fuel pump of the present invention;
[0049] Figure 2 : is a cross-sectional view of the details of the Figure 1 fuel pump having an outlet module;
[0050] Figure 3 : is Figure 2 a cross-sectional view of the outlet module;
[0051] Figure 4 : is Figure 2 a perspective cross-sectional view of a part of the pressure relief valve module of the outlet module;
[0052] Figure 5 : is Figure 2 a perspective cross-sectional view of a part of the pressure relief valve module, the outlet valve of the outlet module, and the outlet valve body; and
[0053] Figure 6 : is Figure 2 a perspective view of a part of the outlet module. DETAILED DESCRIPTION
[0054] Figure 1 Shows an embodiment of the fuel pump 1 of the present invention having an outlet module 15 of the present invention. The general structure and operating principle of the fuel pump 1 are well known and will therefore only be briefly described here. The fuel pump 1 is typically part of a fuel system (not shown) of an internal combustion engine, which generally includes a fuel tank that holds a certain volume of fuel to be supplied to the engine for its operation. The low-pressure fuel pump draws fuel from the fuel tank and raises the pressure of the fuel (e.g., up to 5 bar) for delivery to the (high-pressure) fuel pump 1, which in turn further raises the pressure of the fuel (e.g., to between 10 bar and 50 bar) for delivery to the fuel injector, which then injects the fuel directly into the combustion chamber of the engine's cylinders.
[0055] The fuel pump 1 includes a body 2 having various components, most of which are made of a metal such as stainless steel. The body 2 defines a pumping chamber 3 having a pumping plunger 4, the pumping plunger 4 being adapted to reciprocate within the pumping chamber and being mechanically connectable to a rotating camshaft (not shown) of the engine. The pumping chamber 3 is connected to an inlet passage 5 via an inlet valve 6. Conventionally, the inlet passage 5 is connected to a low-pressure inlet 7 of the fuel pump 1, via which the fuel pump 1 can be connected to the aforementioned low-pressure pump. Fuel enters the pump 1 via the low-pressure inlet 7, flows through a damping volume 8 defined by a damping cup mounted to the body 2, as is known in the art, and then into the inlet passage 5. Although not shown in detail, the inlet valve 6 typically includes a valve seat member 6.1 defining one or more flow orifices that can be sealed by a flexible disc valve member 6.2, which can be raised from the valve seat member by means of an actuating rod controlled by a solenoid actuator. This is just one conventional example of an inlet valve and should not be construed as limiting.
[0056] The body 2 also defines a receiver 9 which is aligned along an outlet axis A and opens to the exterior of the body 2 at a receiver opening 10. The receiver opening 10 is provided on the distal side D relative to the outlet axis A, and the receiver extends towards the proximal side P into the body 2 such that the receiver communicates with the pumping chamber 3. The outlet module 15 of the present invention is partially received in the receiver 9. The outlet module 15 includes a pressure relief valve body 20, an outlet valve body 30, and an outlet fitting 40, each of which is made of a single piece of stainless steel. These elements will be described in detail below. An outlet passage 33, which is partially defined by the outlet valve body 30, connects the pumping chamber 3 to the high-pressure outlet 34 of the fuel pump 1. A pressure relief passage 27, which is partially defined by the pressure relief valve body 20, connects the outlet passage 33 to the pumping chamber 3. The outlet module 15 includes a pressure relief valve 23 and an outlet valve 35. The outlet valve 35 is a one-way valve which allows fuel to flow from the pumping chamber 3 to the outlet 23 if the pressure difference between the pumping chamber 3 and the outlet passage 33 (or more precisely, the portion downstream of the outlet valve 35) exceeds a predetermined outlet pressure. The pressure relief valve 23 is also a one-way valve which allows flow from the outlet passage 33 through the pressure relief passage 27 to the pumping chamber 3 if the pressure in the outlet passage 33 exceeds the pressure in the pumping chamber 3 and the difference is greater than a defined release opening pressure.
[0057] During operation, the reciprocating movement of the pumping plunger 4 causes fuel to be drawn into the pumping chamber 3 from the inlet passage 5 during the intake stroke. During the pumping or compression stroke, the fuel in the pumping chamber 3 is pressurized and discharged through the outlet valve 35 and the outlet passage 33. The fuel can then be supplied via the outlet 34 to a fuel rail connected to the injector described above. During the compression stroke, the inlet valve 6 is selectively closed and prevents backflow through the inlet passage 5. If at any time the pressure in the outlet passage 33 exceeds a predetermined release opening pressure, the pressure relief valve 23 opens to release fuel from the outlet passage 33 through the pressure relief passage 30 to the pumping chamber 3, thereby preventing possible damage to any components downstream of the fuel pump 1.
[0058] Reference will now be made to the appended Figures 2 to 6Let's discuss the details of the outlet module 15. The outlet module 15 is symmetric with respect to the outlet axis A. It includes an external thread 43, which is concentric with the outlet axis A and engages a corresponding internal thread 11 inside the receiver 9. During assembly, the outlet module 15 is inserted into the receiver opening 10 and screwed into the receiver 9 through the mating of the above-mentioned threads 11 and 43. To facilitate tightening, the outlet module 15 includes an external hexagonal drive profile 44. At the end of the tightening process, the first sealing portion 46 of the outlet module 15 engages the second sealing portion 12 of the body 2. Specifically, the first sealing portion 46 includes an annular knife-edge element 47, which cuts into the second sealing portion 12 to provide a knife-edge seal. Thus, the outlet module 15 is connected to the body 2 in a fuel-sealed manner without the need for welding operations that may cause thermal stress and deformation. In this embodiment, the external thread 43, the drive profile 44, the first sealing portion 46, and the knife-edge element 47 are part of the outlet fitting 40.
[0059] The pressure relief valve body 20 and the pressure relief valve 23 are part of the pressure relief valve module 17, which can be best seen in Figure 4 and Figure 5 The pressure relief valve body 20 defines a pressure relief valve chamber 21, in which a first valve seat member 24 having an axial through-hole 24.1 of the pressure relief valve 23, a first valve member 25, and a first spring member 26 are accommodated. These elements are shown respectively in Figure 4 During assembly, the first spring member 26 and the first valve member 25 are inserted into the pressure relief valve chamber 21 through the first distal insertion opening 22, such that the first spring member abuts against the first abutment surface 20.1 of the pressure relief valve body 20. Then the first valve seat member 24 is press-fitted into the pressure relief valve body 20, thereby enclosing the first spring member 26 and the first valve member 25 within the pressure relief valve chamber 21. The press-fit provides a metal-to-metal seal to prevent fuel from flowing around the first valve seat member 24. In addition to receiving the pressure relief valve 23, the pressure relief valve chamber 21 also forms a valve portion 27.1 of the pressure relief passage 27, which will be discussed further below.
[0060] In this embodiment, the first valve member 25 includes an elongated shaft 25.2 (extending parallel to the outlet axis A), a radially protruding head 25.1 at the distal end of the shaft 25.2, and a ball 25.3 on the far side D of the head 25.1. The shaft 25.2 extends through the first spring member 26, and the first spring member 26 abuts against the head 25.1. In Figures 1 to 3 the closed position of the pressure relief valve 23 shown, the ball 25.3 engages the first valve seat element 24 from the proximal side P, where the ball 25.3 thus experiences the pressure in the pumping chamber 3. Although most of the pressure relief valve 23 is in a region communicating with the pumping chamber 3, the sizes of the first valve member 25 and the first spring member 26 are selected such that the dead volume is minimized.
[0061] In the drawing, the first valve member 25 is shown in its closed position, where the ball 25.3 abuts against the first valve seat member 24 due to the biasing force of the first spring member 26, thus closing the through-hole 24.1. If the force acting on the first valve member 25 due to the pressure difference between the proximal side P (pumping chamber side) and the distal side D (outlet side) of the valve seat member 24 overcomes the spring force, the first valve member 25 moves to the proximal side P (i.e., proximally) and the pressure relief valve 23 opens. The spring force in the closed position can be calibrated by adjusting the position of the first valve seat member 24 when the first valve seat member 24 is press-fitted into the pressure relief valve chamber 21. The pressure relief valve body 20 and the pressure relief valve 23 can be pre-assembled to form Figure 5 the pressure relief valve module 17 shown, such that the characteristics of the pressure relief valve 23 can be tested before the outlet module 15 is assembled or installed in the receiver 9.
[0062] The pressure relief passage 27 includes the above-mentioned valve portion 27.1 disposed centrally on the outlet axis A and two first lateral portions 27.2, the two first lateral portions 27.2 originating from the main portion 27.1 and radially traversing the pressure relief valve body 20 in opposite directions. Each first lateral portion 27.2 is aligned with one of a pair of second lateral portions 27.3 that radially traverse the outlet valve body 30. The second lateral portions 27.3 are connected to the annular chamber 13, which is defined inside the receiver 9 between the body 2 and the outlet valve body 30 and is directly connected to the pumping chamber 3.
[0063] As Figure 5 shown, the pressure relief valve module 17 is mainly received in the outlet valve chamber 31 of the outlet valve body 30. During assembly, it is inserted through the second distal insertion opening 32, and the pressure relief valve body 20 is press-fitted into the outlet valve chamber 31. Specifically, the first proximal press-fitting surface 20.3 of the pressure relief valve body 20 engages the second proximal press-fitting surface 30.1 of the outlet valve body 30, and the first distal press-fitting surface 20.4 of the pressure relief valve body 20 engages the second distal press-fitting surface 30.2 of the outlet valve body 30, where the distal press-fitting surfaces 20.4, 30.2 are disposed radially outside the proximal press-fitting surfaces 20.3, 30.1. Thus, a stepped press-fitting structure is formed, which results in a very tight connection, providing a firm mechanical connection as well as a fluid seal.
[0064] In addition to the pressure relief valve module 17, a second spring member 38, which is a helical spring, and a second valve member 37 of the outlet valve 35 are received in the outlet valve chamber 31. During assembly, before inserting the second spring member 38, the spherical second valve member 37 is inserted first, and finally the pressure relief valve module 17 is press-fitted into the outlet valve chamber 31. A radially inwardly projecting portion of the outlet valve body 30 forms a second valve seat member 36 provided with an axial through-hole 36.1. When the pressure relief valve module 17 is installed, the second spring member 38 is compressed between the second valve member 37 and a second abutment surface 20.2 of the pressure relief valve body 20. In Figures 1 to 3 this state, the second valve member 37 is biased by the second spring member 38 against the second valve seat member 36, thereby closing the axial through-hole 36.1; this is the closed position of the outlet valve 35.
[0065] During assembly, the second valve member 37, the second spring member 38, and the pressure relief valve module 17 are assembled with the outlet valve body 30 to form Figure 6 the double valve assembly 16 shown. Before continuing with the assembly, the double valve assembly 16, including the functions of the outlet valve 35 and the pressure relief valve 23, can be tested. Subsequently, the outlet valve body 30 is inserted through the proximal insertion opening 45 of the outlet fitting 40 and press-fitted into the fitting chamber 41. Specifically, a third proximal press-fitting surface 30.3 of the outlet valve body 30 engages a fourth proximal press-fitting surface 40.1 of the outlet fitting 40, and a third distal press-fitting surface 30.4 of the outlet valve body 30 engages a fourth distal press-fitting surface 40.2 of the outlet fitting 40, wherein the proximal press-fitting surfaces 30.3, 40.1 are disposed radially outside the distal press-fitting surfaces 30.4, 40.2. Thus, a stepped press-fitting structure is formed, which results in a very tight connection.
[0066] When the outlet module 15 is fully assembled, it can be connected to the main body 2 as described above. The outlet module 15 can also be tested before connecting it to the main body 2. If any production errors are found at this stage, the outlet module 15 can be replaced without the need to discard the entire fuel pump.
[0067] As described above, the outlet passage 33 is partly defined by the outlet valve body 30. Specifically, the outlet passage 33 includes a proximal portion 33.1 that receives the second spring member 38 and the second valve member 37 of the outlet valve 35, and a distal portion 33.3 that is mainly formed within the fitting cavity 41 of the outlet fitting 40. The proximal portion 33.1 and the external portion 33.3 are symmetric with respect to the outlet axis A and are connected by a plurality (e.g., six) of intermediate portions 33.2 that are parallel to the outlet axis A but radially offset therefrom. These intermediate portions 33.2 are tangentially offset (i.e., circumferentially distributed) by 60° with respect to each other. The proximal portion 33.1 and the intermediate portions 33.2 are produced by machining operations (e.g., by drilling) performed on the outlet valve body 30. Since the axial position of the first lateral portion 27.2 axially overlaps with the axial position of the intermediate portions 33.2, they are tangentially offset such that one first lateral portion 27.2 is disposed between two intermediate portions 33.2. The radial offset of the intermediate portions 33.2 from the outlet axis A allows them to bypass the outlet valve cavity 31 and allows portions of the pressure relief valve 23 and the outlet valve 35 to be positioned closer to the outlet axis A at axial positions that overlap with the axial position of the intermediate portions 33.2.
[0068] Legend of reference numerals:
[0069] 1 Fuel pump
[0070] 2 Body
[0071] 3 Pumping chamber
[0072] 4 Pumping plunger
[0073] 5 Inlet passage
[0074] 6 Inlet valve
[0075] 8 Damping volume
[0076] 9 Receiver
[0077] 10 Receiver opening
[0078] 11 Internal thread
[0079] 12 Second seal
[0080] 13 Annular chamber
[0081] 15 Outlet module
[0082] 16 Double valve assembly
[0083] 17 Pressure relief valve module
[0084] 20 Pressure relief valve body
[0085] 20.1 First adjacent surface
[0086] 20.2 Second adjacent surface
[0087] 20.3 First proximal press-fit surface
[0088] 20.4 First distal press-fit surface
[0089] 21 Pressure relief valve cavity
[0090] 22 First distal insertion opening
[0091] 23 Pressure relief valve
[0092] 24 First valve seat member
[0093] 24.1 Through hole
[0094] 25 First valve member
[0095] 25.1 Head
[0096] 25.2 Shaft
[0097] 25.3 Ball
[0098] 26 First spring member
[0099] 27 Pressure relief passage
[0100] 27.1 Valve portion
[0101] 27.2 First lateral portion
[0102] 27.3 Second lateral portion
[0103] 30 Outlet valve body
[0104] 30.1 Second proximal press-fit surface
[0105] 30.2 Second distal press-fit surface
[0106] 30.3 Third proximal press-fit surface
[0107] 30.4 Third distal press-fit surface
[0108] 31 Outlet valve cavity
[0109] 32 Second distal insertion opening
[0110] 33 Outlet passage
[0111] 33.1 Proximal portion
[0112] 33.2 Intermediate portion
[0113] 33.3 Distal portion
[0114] 34 Outlet
[0115] 35 Outlet Valve
[0116] 36 Second Valve Seat Member
[0117] 37 Second Valve Member
[0118] 38 Second Spring Member
[0119] 40 Outlet Fitting
[0120] 40.1 Fourth Proximal Press-Fit Surface
[0121] 40.2 Fourth Distal Press-Fit Surface
[0122] 41 Fitting Cavity
[0123] 43 External Thread
[0124] 44 Drive Profile
[0125] 45 Proximal Insertion Opening
[0126] 46 First Sealing Portion
[0127] 47 Blade Element
[0128] A Outlet Axis
[0129] D Distal
[0130] P Proximal
Claims
1. A fuel pump (1), the fuel pump comprising a body (2) and an outlet module (15), the body (2) defining: - a pumping chamber (3) having a pumping plunger (4) arranged to reciprocate within the pumping chamber (3); - an inlet passage (5) that at least indirectly connects a low-pressure inlet of the fuel pump (1) to the pumping chamber (3), an inlet valve (6) being adapted to selectively permit flow through the inlet passage (5) to the pumping chamber (3); and - a receiver (9) that opens distally (D) and extends proximally (P) into the body (2) along an outlet axis (A) such that the receiver (9) communicates with the pumping chamber (3), the outlet module (15) being at least partially received within the receiver (9), connected to the body (2) in a fuel-tight manner, and the outlet module comprising: - an outlet passage (33) that at least indirectly connects the pumping chamber (3) to a high-pressure outlet (34) of the fuel pump (1), - an outlet valve (35) that is adapted to selectively permit flow through the outlet passage (33) to the outlet (34), - a pressure relief passage (27) that at least indirectly connects the outlet passage (33) downstream of the outlet valve (35) to the pumping chamber (3), and - a pressure relief valve (23) that is adapted to selectively permit flow through the pressure relief passage (27) to the pumping chamber (3), characterized in that the outlet module (15) comprises an outlet valve body (30) and a pressure relief valve body (20), the outlet valve body at least partially defining the outlet passage (33) and at least partially receiving the outlet valve (35), the pressure relief valve body at least partially defining the pressure relief passage (27) and at least partially receiving the pressure relief valve (23), wherein the pressure relief valve body (20) is at least partially received within an outlet valve cavity (31) of the outlet valve body (30).
2. The fuel pump according to claim 1, wherein, The outlet module (15) comprises an external thread (43) that engages an internal thread (11) of the body (2) inside the receiver (9), the internal thread (11) and the external thread (43) being concentrically arranged about the outlet axis (A).
3. The fuel pump according to any one of the preceding claims, wherein, The outlet module (20) comprises a first sealing portion (46) that engages a second sealing portion (12) of the body (2) inside the receiver (9), wherein at least one of the sealing portions (12, 46) comprises an annular knife-edge element (27) that cuts into the other sealing portion (12, 46) to form a knife-edge seal.
4. The fuel pump according to any one of the preceding claims, wherein, The outlet module (15) comprises an outlet fitting (40), the outlet valve body (30) being at least partially received within the outlet fitting and the outlet fitting (40) being connected to the body (2).
5. The fuel pump according to claim 4, wherein, The outlet valve body (30) is press-fitted into the outlet fitting (40).
6. The fuel pump according to any one of the preceding claims, wherein, The pressure relief valve body (20) is press-fitted into the outlet valve body (30).
7. The fuel pump according to claim 5 or 6, wherein, At least one press-fit connection is achieved using at least two pairs of mating surfaces (20.3, 20.4, 30.1 - 30.4, 40.1, 40.2), which are axially and radially offset relative to each other.
8. The fuel pump according to any one of the preceding claims, wherein, The pressure relief valve body (20) includes a pressure relief valve chamber (21) that has a first distal insertion opening (22) at the distal side (D), through which the pressure relief valve (23) is at least partially inserted into the pressure relief valve chamber (21) during assembly.
9. The fuel pump according to any one of the preceding claims, wherein, The pressure relief valve (23) includes a first valve seat member (24), a first valve member (25), and a first spring member (26) for biasing the first valve member (25) against the first valve seat member (24). The first valve member (25) and the first spring member (26) are disposed in the pressure relief valve chamber (21), and the first valve seat member (24) is press-fitted into the pressure relief valve chamber (21).
10. The fuel pump according to any one of the preceding claims, wherein, The first valve member (25) is at least mostly disposed proximal (P) to the first valve seat member (24) and engages the first valve seat member (24) from the proximal side (P) in the closed position of the pressure relief valve (23), and the first spring member (26) is disposed proximal (P) to the first valve seat member (24) and engages a first abutment surface (20.1) of the pressure relief valve body (20).
11. The fuel pump according to any one of the preceding claims, wherein, The outlet valve body (30) includes a second distal insertion opening (32) at the distal side (D), through which the outlet valve (35) and the pressure relief valve body (20) are at least partially inserted into the outlet valve chamber (31) during assembly.
12. The fuel pump according to any one of the preceding claims, wherein, The outlet valve (35) includes a second valve seat member (36), a second valve member (37), and a second spring member (38) for biasing the second valve member (37) against the second valve seat member (36). The second spring member (37) engages a second abutment surface (20.2) of the pressure relief valve body (20).
13. The fuel pump according to any one of the preceding claims, wherein, The outlet valve body (30) forms the second valve seat member (36).
14. The fuel pump according to any one of the preceding claims, wherein, The outlet passage (33) includes a proximal portion (33.1), a distal portion (33.3), and a plurality of intermediate portions (33.2) connecting the proximal portion (33.1) and the distal portion (33.3). The outlet valve (35) is at least partially received in the proximal portion. The outlet axis (A) traverses the proximal portion (33.1) and the distal portion (33.3), and the intermediate portions (33.2) are offset from the outlet axis (A).
15. The fuel pump according to any one of the preceding claims, wherein, The pressure relief passage (27) includes: a valve portion (27.1) adjacent to the pressure relief valve (23) within the pressure relief valve chamber (21); at least one first lateral portion (27.2) connected to the valve portion (27.1) and extending through the pressure relief valve body (21) to the exterior of the pressure relief valve body; and at least one second lateral portion (27.3) in communication with the at least one first lateral portion (27.2), extending through the outlet valve body (30) to the exterior of the outlet valve body and in communication with the pumping chamber (3).
16. An outlet module (15) for a fuel pump (1), the outlet module including a body (2), the outlet module defining: - a pumping chamber (3) having a pumping plunger (4) arranged to reciprocate within the pumping chamber (3); - an inlet passage (5) that at least indirectly connects a low pressure inlet of the fuel pump (1) to the pumping chamber (3), an inlet valve (6) being adapted to selectively permit flow through the inlet passage (5) to the pumping chamber (3); and - a receiver (9) opening towards the distal side (D) and extending towards the proximal side (P) along an outlet axis (A) into the body (2) such that the receiver (9) is in communication with the pumping chamber (3), the outlet module (15) being adapted to be at least partially received within the receiver (9), connected to the body (2) in a fuel - sealed manner, and the outlet module including: - an outlet passage (33) that at least indirectly connects the pumping chamber (3) to a high pressure outlet (34) of the fuel pump; - an outlet valve (35) adapted to selectively permit flow through the outlet passage (33) to the outlet (34); - a pressure relief passage (27) that at least indirectly connects the outlet passage (33) downstream of the outlet valve (35) to the pumping chamber (3); and - a pressure relief valve (23) adapted to selectively permit flow through the pressure relief passage (27) to the pumping chamber (3), characterized in that the outlet module (15) includes an outlet valve body (30) and a pressure relief valve body (20), the outlet valve body at least partially defining the outlet passage (33) and at least partially receiving the outlet valve (35), the pressure relief valve body at least partially defining the pressure relief passage (27) and at least partially receiving the pressure relief valve (23), wherein the pressure relief valve body (20) is at least partially received within an outlet valve cavity (31) of the outlet valve body (30).