Fuel pump
By integrating the pressure relief channel and outlet channel into a single outlet module and adopting a threaded connection and sealing design, the problem of weakened structure and difficult replacement of faulty components in the fuel pump is solved, achieving higher assembly accuracy and stability.
Patent Information
- Application Number
- CN202380040487.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-16
- Filing Date
- 2023-05-12
- Publication Date
- 2025-01-03
AI Technical Summary
In the existing fuel pump design, the integrated pressure relief valve and outlet valve are complex, resulting in weakened structure and difficult replacement of faulty components, increasing the scrap rate.
A fuel pump is designed in which the pressure relief passage and outlet passage are integrated into a single outlet module, allowing independent testing and replacement, reducing machining requirements for the body structure, and improving sealing and stability through threaded connection and sealing design.
It realizes more accurate functional testing and fault identification during the assembly process of fuel pumps, reduces waste rate, and improves the structural stability and sealing performance of the outlet module.
Smart Images
Figure CN119256156A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a fuel pump and an outlet module for the fuel pump. Background Art
[0002] Fuel systems in modern internal combustion engines fueled by gasoline, especially those for the automotive market, mostly use gasoline direct injection (GDi). In these systems, a fuel injector injects fuel directly into the combustion chamber of the internal combustion engine. Typically, the fuel from the fuel tank is supplied at a relatively low pressure by a low-pressure fuel pump, which is usually an electric fuel pump located inside the fuel tank. The low-pressure fuel pump supplies the fuel to a high-pressure fuel pump (also known as a GDi pump), which typically includes a pumping plunger that reciprocates through the camshaft of the internal combustion engine. During the intake stroke, the fuel is drawn into the pumping chamber, and in the subsequent pumping stroke, the pumping plunger also pressurizes the fuel so that it can be supplied to the fuel injector at high pressure.
[0003] For safe operation, the GDi pump includes a pressure relief channel with an embedded pressure relief valve to avoid any overpressure that could burst the pump or any part of 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 injector maximum opening pressure (MOP). In order to avoid backflow from the fuel rail into the pumping chamber, the fuel pump also includes an outlet valve, which is arranged in the outlet channel on the high-pressure side of the pumping chamber. Integrating these valves into the fuel pump usually leads to a complex design, and the various channels may weaken the overall structure of the fuel pump body. Another problem is that the design of the pressure relief valve and / or outlet valve in the art usually only allows for checking whether the function is normal at a later stage of the assembly process, when a single faulty component means that the main components of the fuel pump must be scrapped.
[0004] Purpose 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 . Summary of the invention
[0007] The present invention relates to a fuel pump. More specifically, it relates to a fuel pump for an internal combustion engine, in particular for a motor vehicle like 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. The high-pressure pump then increases the pressure of the fuel, typically to at least 100 bar, sometimes up to 600 bar or even higher.
[0008] The fuel pump comprises a pumping chamber with a pumping plunger, which is arranged to reciprocate in the pumping chamber. By the action of the pumping plunger, fuel can be sucked into the pumping chamber during the intake stroke, and the fuel can be subsequently pressurized and discharged from the pumping chamber during the compression stroke or the pumping stroke. Therefore, the fuel enters the pumping chamber at a low pressure and leaves the pumping chamber at a high pressure. The pumping plunger can be operated electrically, or it can be mechanically linked to an engine, in particular to the internal combustion engine to which the fuel pump supplies fuel. For example, the pumping plunger can be linked to the camshaft of the engine. Since the plunger reciprocates along a straight line (i.e., moves back and forth), at least a portion of the pumping chamber is cylindrical, wherein the cross section corresponds to the cross section of the plunger. However, the pumping chamber may include at least a portion that is inaccessible to the plunger, and the portion may have a non-cylindrical shape. It should be understood that the pumping chamber and the passage described below are all defined inside the housing of the fuel pump.
[0009] The fuel pump also includes an inlet channel, which at least indirectly connects the low-pressure inlet of the fuel pump to the pumping chamber, and the inlet valve is suitable for selectively enabling fluid to flow through the inlet channel to the pumping chamber. The low-pressure inlet is suitable for connecting to a low-pressure fuel source, typically a low-pressure pump. Instead of "low-pressure inlet", this can be simply referred to as "inlet", and the term "low pressure" means that the fuel entering the inlet has not yet been pressurized by the fuel pump. Of course, the connection with the fuel source can be indirect, such as via a pipe, a hose, etc. The inlet channel directly or indirectly establishes a fluid connection or fluid communication between the inlet and the pumping chamber. In the case of an indirect connection, the inlet channel is connected to another channel connected to the inlet. During the intake stroke of the plunger, the fuel is sucked into the pumping chamber through the inlet channel. Here and below, the term "channel" refers to any volume suitable for receiving fuel and allowing the fuel to be transferred from a source (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 unbranched. The inlet valve is suitable for selectively enabling fluid to 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., backflow toward the inlet passage. In other words, the pressure on the inlet side of the inlet valve is at least a 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 arranged on or inside the inlet passage, such as near the inlet, near the pumping chamber, or somewhere in between. In order to minimize the pumping dead volume, most preferably, the inlet valve is arranged close to the pumping chamber.
[0010] In addition, the fuel pump comprises an outlet channel which at least indirectly connects the pumping chamber to a high-pressure outlet of the fuel pump, and an outlet valve is adapted to selectively enable a fluid to flow through the outlet channel to the outlet. The outlet channel is 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" means 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, the fuel is pressurized in the pumping chamber and then discharged from the pumping chamber through the outlet channel. The outlet valve is adapted to selectively enable a fluid to flow through the outlet channel to the pumping chamber. The outlet valve is typically a one-way valve (check valve type) which prevents the fuel from flowing in the opposite direction (i.e. towards the pumping chamber). In addition, the outlet valve is capable of only enabling the fluid to flow towards the outlet if a certain opening pressure is exceeded. The outlet valve can be arranged inside the outlet channel, for example close to the outlet, close to the pumping chamber or somewhere in between. In order to minimize the pumping dead volume, most preferably the outlet valve is arranged close to the pumping chamber.
[0011] In addition, the fuel pump includes a pressure relief channel, which connects the outlet channel downstream of the outlet valve to the pumping chamber, and the pressure relief valve is suitable for selectively enabling the fluid to flow through the pressure relief channel to the pumping chamber. The pressure relief channel originates from the outlet channel downstream of the outlet valve and leads to the pumping chamber. Therefore, fuel can be released from the outlet channel into the pumping chamber through the pressure relief channel. The function of the pressure relief channel is to prevent overpressure in the outlet channel and / or, for example, a fuel rail connected to the outlet channel. The pressure relief valve is suitable for selectively enabling the fluid to flow through the pressure relief channel to 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 channel). In addition, if a certain opening pressure is exceeded, the pressure relief valve only allows the fuel to flow toward the pumping chamber. In other words, if the pressure difference between the outlet channel and the pumping chamber is high enough, the pressure relief valve opens to release the fuel from the outlet channel through the pressure relief channel. The pressure relief valve may be arranged inside the pressure relief passage, such as near the outlet passage, near the pumping chamber, or somewhere in between.
[0012] According to the present invention, the fuel pump comprises a main body and an outlet module. The main body defines the inlet channel, the pumping chamber and the container, the container is open toward the distal side, and extends into the main body toward the proximal side along the outlet axis so that the container is communicated with the pumping chamber. The inlet channel, the pumping chamber and the container are volumes or spaces defined by the main body. The main body (which is usually at least partially made of metal to provide the necessary pressure resistance and stability) is advantageously made of a single piece. The inlet valve can be received inside the main body or can be regarded as a part of the main body. In addition to the inlet channel and the pumping chamber, the main body also defines the above-mentioned container, which is a recess inside the main body. More specifically, it is an open recess, that is, it is open toward the distal side (the main body has a container opening on the distal side). The container extends into the main body toward the proximal side along the outlet axis, and the proximal side is opposite to the first side relative to the outlet axis. More specifically, it extends into the main body so that it is communicated with the pumping chamber. In other words, the pumping chamber and the container are directly or indirectly connected.
[0013] The outlet module comprises an outlet module body in which an outlet valve and a pressure relief valve are received, and the outlet module body defines the outlet channel and the pressure relief channel (or at least a portion thereof), the outlet module body is at least partially received in the container, and is connected to the main body in a fuel-tight manner. The outlet channel and the pressure relief channel are defined or defined by the outlet module body, that is, they are arranged inside the outlet module body. The outlet valve and the pressure relief valve are received in the outlet module body, that is, they are arranged inside the outlet module body. In other words, the outlet channel, the pressure relief channel and the corresponding valve mechanism are combined inside the outlet module body of the outlet module. The outlet module body is in turn fully or at least partially received in the container. It should be understood that the design of the outlet module body and its position inside the container are adjusted so that the outlet channel and the pressure relief channel can be communicated with the pumping chamber as described above. In order to prevent any fuel from leaking through the container, the outlet module body is connected to the main body in a fuel-tight manner.
[0014] The design of the present invention allows for the integration of the outlet and the pressure relief function in a single outlet module, which can be produced and assembled separately from the main body. Before the outlet module body is inserted into the container, the correct function of the outlet module, in particular the function of the outlet valve and the pressure relief valve, can be tested. Therefore, before the final assembly of the fuel pump, production errors or assembly errors can be identified, which greatly helps to reduce waste. In the worst case, only the faulty outlet module needs to be replaced. In some embodiments, even only a part of the outlet module can be replaced, thereby further reducing waste. In addition, integrating the pressure relief channel into the outlet module reduces the need for machining operations on the main body. In fuel pumps known in the art, the pressure relief channel usually represents a structural weakness of the main body. The design of the present invention eliminates this weakness. Integrating the pressure relief channel into the outlet module body usually allows for the design of a structure that does not weaken the outlet module body in a similar manner.
[0015] According to a preferred design, the outlet module body includes an external thread, which is engaged with the internal thread of the main body inside the container, and the internal thread and the external thread are concentrically arranged around the outlet axis. During assembly, when the internal thread and the external thread are engaged, the outlet module body is screwed into the container. Since these threads are concentric with respect to the outlet axis, a considerable axial force (along the outlet axis direction) can be applied between the main body and the outlet module body. This axial force can be used to provide a fuel seal between the main body of the outlet module body. For example, compared with a welded connection that may cause thermal stress and cause the main body and / or the outlet module body to deform, the threaded connection is advantageous.
[0016] Specifically, the outlet module body may include a first sealing portion that engages with a second sealing portion of the body inside the container. Preferably, at least one sealing portion includes an annular blade element that cuts into the other sealing portion to form a knife edge seal. In this embodiment, the outlet module body and the body include corresponding sealing portions that are directly engaged with each other to provide a fuel seal. One of the sealing portions includes an annular blade element that typically has a pointed, wedge-shaped or blade-shaped profile. The blade element is annular and concentric around the outlet axis. Through the threading action between the first thread and the second thread, the blade 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 blade element is sufficient to allow it to cut into the other sealing portion, thereby providing a knife edge seal. As is well known, this seal is very reliable and can withstand high pressures.
[0017] The outlet module body is made of a single piece. In other words, a single piece (of metal) is used for the outlet module body, which typically undergoes various machining operations, for example, for providing the outlet channel and the pressure relief channel, the external thread (if present) or other features. However, at least some features of the outlet module body may be defined by an initial casting process. The single-piece design facilitates assembly of the outlet module and increases the structural stability of the outlet module body.
[0018] If the outlet module body comprises a distal insertion opening on the distal side, the assembly process will be further facilitated to be simplified, during which the pressure relief valve is inserted into the outlet module body through the distal insertion opening. The distal insertion opening is designed to allow the pressure relief valve to be inserted into the outlet module body. It is arranged on the distal side, which means that the pressure relief valve will move towards the proximal side when inserted. If, as is usually the case, the pressure relief valve comprises several components, these components can be pre-assembled outside the outlet module body before the entire pressure relief valve is inserted. Optionally, this can allow the pressure relief valve to be tested before it is inserted into the outlet module body. It can also help to identify production or assembly errors in the pressure relief valve at an early stage, so that a faulty pressure relief valve can be discarded and replaced with a good pressure relief valve without having to scrap the entire outlet module. In some embodiments, the distal insertion opening is the (high pressure) outlet of the fuel pump.
[0019] Preferably, the pressure relief valve comprises a first seat member, a first valve member and a first elastic member for biasing the first valve member against the first seat member, the first seat member being press-fitted into the outlet module body. The first valve member and the first seat member cooperate to provide the valve mechanism, wherein the first seat member represents a fixed portion of the pressure relief valve and the first valve member represents a movable portion. The first elastic member acts directly or indirectly between the first seat member and the first valve member. Through the action of the first elastic member, the first valve member is biased against the first seat member into 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 elastic member to move the first valve member into the open position, thereby opening the pressure relief valve. The first seat member is press-fitted into the outlet module body, thereby providing a fluid-tight connection while avoiding welding operations that may cause deformation or thermal stress, for example.
[0020] One embodiment provides that the first seat member comprises a through hole extending from a pump side communicating with the pumping chamber to an outlet side communicating with the outlet channel, the first valve member has a head for engaging the first seat member from the pump side in the closed position of the pressure relief valve and an elongated shaft passing through the through hole, the first elastic member being arranged on the outlet side and engaging a stop member rigidly connected to the shaft. The pump side of the seat member is the side communicating with the pumping chamber and is therefore affected by pressure changes in the pumping chamber. The outlet side is in communication with the outlet channel and is therefore subject to the pressure in the outlet channel. The outlet side may also be referred to as the high pressure side. The first valve member comprises at least a head and a shaft, wherein the shaft passes from the pump side through the through hole of the first seat member to the outlet side, and the head is too large to pass through the through hole. Instead, the head engages with an annular seat surrounding the through hole. The overall shape of the first valve member may be compared to a needle. The shaft is elongated and has a length that generally corresponds to at least 5, 10 or 15 times its (maximum) thickness. The thickness of the shaft can be constant or can vary along its length. On the other hand, the head is a part of the valve member that is wider than the shaft. The first elastic member engages with a stop member rigidly connected to the shaft, preferably near the outlet side end of the shaft. In either case, the first elastic member is arranged on the outlet side, which is also the case for most of the shaft. Therefore, the main part of the pressure relief valve is arranged on the outlet side. This is advantageous because the size of the pressure relief valve can be increased (for example, a stronger and larger first elastic member is provided) without increasing the pumping dead volume. In addition, since the first elastic member is preloaded by the stop member, the preload of the first elastic member can be verified (and possibly adjusted) before the pressure relief valve is inserted into the outlet module body.
[0021] Preferably, the stop member is press-fitted to the shaft. This allows easy calibration of the pressure relief valve. The opening pressure of the pressure relief valve depends, among other factors, on the prestress of the first elastic member, which prestress can be calibrated by adjusting the position of the stop member. In this embodiment, the stop member is produced separately from the shaft and is positioned on the shaft according to the required opening pressure. In a preferred embodiment, the functioning of the outlet module can be tested before the outlet module is inserted into the container and even before the pressure relief valve is inserted into the outlet module body.
[0022] The pressure relief valve may include a guide sleeve mounted on the shaft and surrounded by the first elastic member, the guide sleeve extending from the first seat member toward the stop member. Typically, the guide sleeve is securely connected to the first seat member. Its overall shape is typically elongated, and it may extend along a majority (e.g., at least 50% or at least 70%) of the shaft. The guide sleeve is interposed between the shaft and the first elastic member (which is typically a coil spring) to guide the movement of the first valve member and prevent any interference between the shaft and the first elastic member. Optionally, the guide sleeve may also be an abutment element for the stop member, i.e., when the stop member abuts the guide sleeve, it may limit the movement of the stop member (and the first valve member).
[0023] If the outlet module body comprises a proximal insertion opening on the proximal side, the assembly process is further facilitated, during which the outlet valve is inserted into the outlet module body through the proximal insertion opening. The proximal insertion opening is designed to allow the outlet valve to be inserted into the outlet module body. It is arranged on the proximal side, which means that the outlet valve will move towards the distal side when inserted. According to this design, the various components of the outlet valve can be pre-assembled outside the outlet module body, or they can be inserted one by one. This first option can allow for testing the outlet valve before inserting it into the outlet module body.
[0024] Preferably, the outlet valve comprises a second seat member, a second valve member and a second elastic member for biasing the second valve member against the second seat member, the second seat member being press-fitted into the outlet module body. Similarly, the second seat member represents the stationary portion of the outlet valve, while the second valve member represents the movable portion. The second elastic member acts directly or indirectly between the second seat member and the second valve member, thereby biasing the second valve member against the second seat member and into 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 elastic member so that the second valve member moves to the open position, thereby opening the outlet valve. The second seat member is press-fitted into the outlet module body, thereby providing a fluid connection while avoiding welding operations that may cause deformation or thermal stress, for example.
[0025] In this case, the press fit may be enough to provide reliable connection between the second seat member and the outlet module body. In some cases, this connection may also be improved. According to such an embodiment, the edge portion of the outlet module body around the second opening is curled, so that the second seat member is maintained in the outlet module body inside in a form-fitting manner. This corresponding curling operation reduces the diameter of the second opening, so that no matter how the press fit is, the second seat member can not be removed through the second opening.
[0026] One embodiment provides that the outlet channel comprises a proximal portion in which the outlet valve is at least partially received, a distal portion in which the pressure relief valve is at least partially received, and a plurality of intermediate portions connecting the proximal portion and the distal portion, the outlet axis passing through the proximal portion and the distal portion, and the intermediate portions deviating from the outlet axis. Typically, the proximal portion is farthest from the exterior of the body. The proximal portion can be arranged adjacent to the inlet channel. The outlet valve is at least partially received in the proximal portion. The distal portion is typically arranged farthest from the inlet channel and closest to the outlet or even including the outlet. The pressure relief valve is at least partially received in the distal portion. The proximal portion and the distal portion are connected by a plurality of intermediate portions (e.g., between two and five, preferably three or four). While the outlet axis passes through the proximal portion and the distal portion, the intermediate portion is arranged to deviate from the outlet axis, which can be said to be radially deviated from the outlet axis. This can facilitate a compact design of the outlet module, since the offset arrangement of the middle section allows for arranging other elements near or on the outlet axis. It is even possible that the axial position of the proximal part and / or the distal part overlaps the axial position of the middle section, wherein the middle section is radially arranged outside the proximal part or the distal part. According to one embodiment, the middle section extends parallel to the outlet axis. This facilitates the production of the outlet module body, since the middle section can be drilled, for example, by a parallel drilling operation.
[0027] According to another embodiment, at least one of the outlet valve, the pressure relief valve and the outlet passage is at least mostly symmetrical with the outlet axis. "At least mostly symmetrical" means that some (minor) components may not be symmetrical, but the overall configuration is symmetrical. This symmetrical design can contribute to the production and assembly of the outlet module. In addition, it may contribute to optimizing the fuel flow through the outlet module. With regard to the pressure relief valve, preferably, the first valve member, the first seat member and the first elastic member are all symmetrical with the outlet axis. The same applies to the second valve member, the second seat member and the second elastic member of the outlet valve. In this case, if the spring axis of the coil spring coincides with the outlet axis, it is considered that the coil spring is symmetrical with the outlet axis. If the outlet passage has a proximal portion, a distal portion and a middle portion, the middle portion can be arranged on a circle concentric with the outlet axis and evenly spaced apart along the tangential direction.
[0028] The pressure relief passage may include a main portion adjacent to the pressure relief valve and a plurality of branch portions connected to the main portion, which pass through the outlet module body to reach its exterior and are communicated with the pumping chamber. The main portion is usually arranged near the outlet axis and may be symmetrical relative to it. It is arranged adjacent to the pressure relief valve, and the pressure relief valve is usually directly communicated with the main portion. The branch portions fork / separate from the main portion and constitute a separate connection between the main portion and the exterior of the outlet module body. They may be arranged symmetrically relative to the outlet axis. The branch portions may be straight and may be produced by drilling. Typically, they are not parallel to the outlet axis, but are arranged at an angle (e.g., at least 20° or at least 40°) to the outlet axis. They may even be arranged radially relative to the outlet axis. In some embodiments, the axial position of the branch portions may overlap the axial position of the intermediate portion. In this case, the different portions deviate tangentially from each other to avoid any interference.
[0029] The invention also relates to an outlet module for a fuel pump, the fuel pump comprising a body, the body defining:
[0030] - a pumping chamber having a pumping plunger arranged to reciprocate within the pumping chamber,
[0031] an inlet channel at least indirectly connecting a low-pressure inlet of the fuel pump to the pumping chamber, the inlet valve being adapted to selectively enable a fluid flow through the inlet channel to the pumping chamber;
[0032] as well as
[0033] - a container which is open towards the distal side and which extends into the body along an outlet axis towards the proximal side such that the container communicates with the pumping chamber.
[0034] According to the present invention, the outlet module has an outlet module body in which the outlet valve and the pressure relief valve are received, and the outlet module body defines an outlet channel and a pressure relief channel, and the outlet module body is adapted to be at least partially received in the container and connected to the main body in a fuel-tight manner, so that,
[0035] - the outlet channel at least indirectly connects the pumping chamber to a high-pressure outlet of the fuel pump, the outlet valve being adapted to selectively enable fluid to flow through the outlet channel to the outlet; and
[0036] - the pressure relief channel connects the outlet channel downstream of the outlet valve to the pumping chamber, the pressure relief valve being adapted to selectively enable fluid to flow through the pressure relief channel to the pumping chamber;
[0037] All these terms have been explained above with respect to the fuel pump of the present invention and will therefore not be explained again. Preferred embodiments of the outlet module of the present invention correspond to the embodiments of the fuel pump of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The present invention will now be described by way of example with reference to the accompanying drawings, in which:
[0039] Figure 1 : is a cross-sectional view of a fuel pump of the present invention;
[0040] Figure 2 :yes Figure 1 A partial cross-sectional view of a fuel pump; and
[0041] Figure 3 :yes Figure 1 A three-dimensional cross-sectional view of an outlet module body of a fuel pump. DETAILED DESCRIPTION
[0042] Figure 1A fuel pump 1 according to the invention is shown with an outlet module 20 according to the invention. The general structure and working 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 typically includes a fuel tank that receives a certain volume of fuel to supply the engine for its operation. A low-pressure fuel pump draws fuel from the fuel tank and increases the pressure of the fuel (e.g., up to 5 bar) for delivery to a (high-pressure) fuel pump 1, which in turn further increases the pressure of the fuel (e.g., to between 10 bar and 50 bar) for delivery to a fuel injector, which then injects the fuel directly into the combustion chamber of a cylinder of the engine.
[0043] The fuel pump 1 includes a body 2 having various components, most of which are made of metal (e.g., stainless steel). The body 2 defines a pumping chamber 3 having a pumping plunger 4, which is adapted to reciprocate in the pumping chamber and can be mechanically linked to a rotating camshaft (not shown) of the engine. The pumping chamber 3 is connected to an inlet passage 5 using an inlet valve 6. Conventionally, the inlet passage 5 is connected to a low-pressure inlet (not visible in the figure) of the fuel pump 1, via which the fuel pump 1 can be connected to the above-mentioned low-pressure pump. As is known in the art, the fuel enters the pump 1 via the low-pressure inlet, flows through a damping volume 8 defined by a damping cup mounted to the body 2, and then enters the inlet passage 5. Although not shown in detail, the inlet valve 6 generally includes a seat member, which defines one or more flow holes, which can be sealed by a flexible disc valve member, which can be raised from the seat member by an actuating rod controlled by an electromagnetic actuator. This is only a conventional example of an inlet valve and should not be interpreted as limiting.
[0044] The body 2 also defines a container 9, which is aligned along the outlet axis A and opens to the outside of the body 2 at the container opening 10. The container opening 10 is arranged on the distal side D relative to the outlet axis A, and the container extends into the body 2 towards the proximal side P, so that it communicates with the pumping chamber 3. The outlet module 20 of the present invention is partially received in the container 9. The outlet module 20 includes an outlet module body 21 made of a single piece of stainless steel. The outlet module body 21 defines an outlet channel 27 and a pressure relief channel 31, which connects the pumping chamber 3 to the high-pressure outlet 28 of the fuel pump 1, and the pressure relief channel connects the outlet channel 27 to the pumping chamber 3. The pressure relief valve 40 and the outlet valve 50 are received inside the outlet module body 21. The outlet valve 50 is a one-way valve that enables fuel to flow from the pumping chamber 3 to the outlet 23 if the pressure on the pumping chamber 3 side exceeds a predetermined outlet pressure (set by the spring 53 and the pressure in 27.2). The pressure relief valve 40 is also a one-way valve that enables fluid to flow from the outlet channel 27 through the pressure relief channel 31 to the pumping chamber 3 if the pressure in the outlet channel 27 exceeds the pressure in the pumping chamber 3 and the difference is greater than a defined pressure relief opening pressure.
[0045] During operation, the reciprocating motion of the pumping plunger 4 causes fuel to be drawn from the inlet passage 5 into the pumping chamber 3 during the intake stroke. During the subsequent pumping or compression stroke, the fuel in the pumping chamber 3 is pressurized and discharged through the outlet valve 50 and the outlet passage 27. The fuel can then be supplied to a fuel rail connected to the above-mentioned injectors via the outlet 28. During the compression stroke, the inlet valve 6 is closed, thereby preventing backflow through the inlet passage 5. If at any time, the pressure in the outlet passage 22 exceeds the predetermined pressure relief opening pressure, the pressure relief valve 40 opens to release fuel from the outlet passage 22 through the pressure relief passage 30 into the pumping chamber 3, thereby preventing possible damage to any components downstream of the fuel pump 1.
[0046] Now refer to Figure 2 and Figure 3The details of the outlet module 20 are discussed. The outlet module body 21 is symmetrical with respect to the outlet axis A. It includes an external thread 22, which is concentric with the outlet axis A and engages with the corresponding internal thread 11 on the inner side of the container 9. During assembly, the outlet module body 21 is inserted through the container opening 10 and is screwed into the container 9 by the cooperation of the above-mentioned threads 11 and 22. To facilitate screwing, the outlet module body 21 includes an external hexagonal drive profile 23. At the end of the screwing process, the first sealing surface 24 of the outlet module body 21 engages with the second sealing surface 12 of the main body 2. Specifically, the first sealing surface 24 includes an annular blade element 25, which cuts into the second sealing surface 12 to provide a knife edge seal. Therefore, the outlet module body 21 is connected to the main body 2 in a fuel-tight manner without the need for welding operations that may cause thermal stress and deformation.
[0047] The outlet channel 27 and the pressure relief channel 31 are produced by machining operations (such as drilling) performed on the outlet module body 21. Specifically, the outlet channel 27 includes a proximal portion 27.1 in which the outlet valve 50 is received and a distal portion 27.3 in which the main portion of the pressure relief valve 40 is received and leads to the outlet 28. The proximal portion 27.1 and the distal portion 27.3 are symmetrical with respect to the outlet axis A and are connected by three intermediate portions 27.2 that are parallel to the outlet axis A but radially offset from the outlet axis A. These intermediate portions 27.2 are tangentially offset by 120° relative to each other. The pressure relief channel 31 includes a main portion 31.1 arranged with the outlet axis A as the center and three branch portions 31.2, which originate from the main portion 311 at an angle of, for example, 70° relative to the outlet axis A. These branch portions 31.2 are also arranged symmetrically around the outlet axis A, so they are tangentially offset by 120° relative to each other. Since the axial position of the branch portions 31.2 overlaps with the axial position of the intermediate portions 27.2, they are tangentially offset so that one branch portion 31.2 is arranged between two intermediate portions 27.2, and vice versa. The radial offset of the intermediate portions 27.2 from the outlet axis A allows the components of the pressure relief valve 40 and the outlet valve 50 to be positioned close to the outlet axis A in an axial position, which overlaps with the axial position of the intermediate portions 27.2. In addition, the main portion 31.1 can be arranged close to the outlet axis A without interfering with the intermediate portions.
[0048] The pressure relief valve 12 is mainly received in the distal part 27.3 of the outlet passage 27, that is, it is located downstream of the outlet valve 50. It includes a first seat member 41, a first valve member 42, a first elastic member 43, a stop member 44 and a guide sleeve 45. The first seat member 41 is press-fitted into the outlet module body 21 at the transition between the distal part 27.3 and the main part 31.1. The press fit provides a metal-to-metal seal, thereby preventing fuel from flowing around the seat member 41. The central through hole 41.1 extends from the pump side 46 to the outlet side 47 of the seat member 41, that is, it can also be said that it extends from the proximal side P of the seat member 41 to the distal side D. The annular seat 41.2 is arranged on the pump side 46 and surrounds the through hole 41.1. The seat member 41 includes an enlarged hole section axially continuous with the through hole 41.1 on the first distal side, and the guide sleeve 45 is partially received in the hole section, preferably press-fitted.
[0049] The first valve member 42 comprises an elongated shaft 42.2 (extending parallel to the outlet axis A) and a radially protruding head 42.1 at the proximal end of the shaft 42.2. The shaft 42.2 extends through the through hole 41.1, while the head 42.1 cannot pass through the through hole 41.1 due to its larger diameter. Figure 1 and Figure 2 , the head 42.1 engages the annular seat 41.2 from the pump side 46, which is in communication with the pumping chamber 3 and is therefore subjected to the pressure in the pumping chamber 3. Most of the shaft 42.2, the stop member 44, the first elastic member 43 and the guide sleeve 45 are arranged on the outlet side 47 of the first seat member 41, i.e. in communication with or in the outlet channel 27. Therefore, as long as the pressure relief valve 40 is closed, most of the pressure relief valve 40 is in an area that is not in communication with the pumping chamber 3 and is therefore not part of the dead volume. Even if the size of the pressure relief valve 40 is increased, this dead volume can be kept small.
[0050] In the figure, the first valve member 42 is shown in its closed position, in which the head 42.1 sits against the annular seat 41.2 due to the biasing force of the first elastic member 43. If the force acting on the first valve member 42 due to the pressure difference between the pump side 46 and the outlet side 47 overcomes the spring force, the first valve member 42 moves to the pump side 46 (i.e., the proximal end), and the pressure relief valve 40 opens. By adjusting the position of the stop member 44 on the shaft 42.2, the spring force of the closed position can be calibrated. In this embodiment, the stop member 44 is an annular member with a center hole therein, and its size is designed to be fixed to the shaft 42.2 by press fitting. The position of the stop member 44 (which is easy to adjust) determines the opening pressure of the pressure relief valve 40. The guide sleeve 45 is installed on the shaft 42.2 and is press-fitted into the first seat member 41. The guide sleeve 45 is arranged to keep the shaft 42.1 and the first valve member 42 as a whole in axial alignment, in particular when the head 42.1 is lifted from the seat 41.2. In order to allow for fluid communication and pressure exchange, a gap is provided between the shaft 42.1 and the guide sleeve 45.
[0051] In order to assemble the outlet module 20, the pressure relief valve 40 can be pre-assembled before it is inserted into the outlet module body 21 through the distal insertion opening 29 (the outlet 28 in this embodiment). It is retained in the outlet module body 21 by the press fit of the first seat member 41. Therefore, the pressure relief valve 40 can be tested before the pressure relief valve 40 is inserted, and the biasing force of the first elastic member 43 can be calibrated by adjusting the position of the stop member 44 on the shaft 42.2. Therefore, before the pressure relief valve 40 is inserted into the outlet module body 21, the faulty pressure relief valve 40 can be identified and replaced. In other words, it is usually not necessary to discard the entire outlet module 20, which greatly reduces waste. The outlet module 20 can also be tested before it is connected to the main body 2. If any production errors are found at this stage, the outlet module 20 can be replaced without discarding the entire fuel pump.
[0052] The outlet valve 50 is received in the proximal part 27.1. During assembly, it is inserted through the proximal insertion opening 30 on the proximal side P of the outlet module body 21. More specifically, the second elastic member 53, which is a coil spring, is first inserted, then the spherical second valve member 52 is inserted, and finally the second seat member 51 is press-fitted into the proximal part 27.1. The second seat member 51 has a cup shape and is provided with a flow hole at its bottom. The second valve member 52 is at least partially received in the cup-shaped seat member 51 and is movable therein. Figure 2 In the embodiment, the second valve member 52 is biased by the spring 53 against the seat member 51, thereby closing the hole: the second valve 50 is closed. In order to provide a more stable connection, the rim portion 26 circumferentially arranged around the proximal insertion opening 30 is curled to retain the outlet valve 50 in a form-fitting manner.
[0053] Legend to the accompanying drawings:
[0054] 1 Fuel pump
[0055] 2 Main body
[0056] 3 Pumping chamber
[0057] 4 Pumping plunger
[0058] 5 Entryway
[0059] 6 Inlet valve
[0060] 8 Damping volume
[0061] 9 Container
[0062] 10 Container opening
[0063] 11 Internal thread
[0064] 12 Second sealing surface
[0065] 20 Exit module
[0066] 21 Exit module body
[0067] 22 External thread
[0068] 23 Drive profile
[0069] 24 First sealing surface
[0070] 25 Blade element
[0071] 26 Edge
[0072] 27 Exit Channel
[0073] 27.1 Proximal part
[0074] 27.2 Middle part
[0075] 27.3 Distal part
[0076] 28 Exit
[0077] 29 Distal insertion opening
[0078] 30 Proximal insertion opening
[0079] 31 Pressure relief channel
[0080] 31.1 Main Part
[0081] 31.2 Branching
[0082] 40 Pressure relief valve
[0083] 41 First component
[0084] 41.1 Through Hole
[0085] 41.2 seats
[0086] 42 first valve member
[0087] 42.1 Head
[0088] 42.2 Axis
[0089] 43 first elastic member
[0090] 44 Stop member
[0091] 45 Guide sleeve
[0092] 46 Pump side
[0093] 47 Exit side
[0094] 50 Outlet valve
[0095] 51 Second component
[0096] 52 second valve member
[0097] 53 second elastic member
[0098] A Exit axis
[0099] D Distal side
[0100] P proximal side
Claims
1. A fuel pump (1), comprising: - a pumping chamber (3) having a pumping plunger (4) arranged to reciprocate within the pumping chamber (3); - an inlet channel (5) at least indirectly connecting a low-pressure inlet of the fuel pump (1) to the pumping chamber (3), an inlet valve (6) being adapted to selectively allow a fluid to flow through the inlet channel (5) to the pumping chamber (3); an outlet channel (27) at least indirectly connecting the pumping chamber (3) to a high-pressure outlet (28) of the fuel pump, an outlet valve (50) being adapted to selectively allow a fluid to flow through the outlet channel (27) to the outlet (28); a pressure relief channel (31) connecting the outlet channel (27) downstream of the outlet valve (50) to the pumping chamber (3), the pressure relief valve (40) being adapted to selectively allow a fluid to flow through the pressure relief channel (31) to the pumping chamber (3); The fuel pump (1) comprises a body (2), the body defining a container (9), the inlet channel (5) and the pumping chamber (3), the container opening toward the distal side (D) and extending into the body (2) along the outlet axis (A) toward the proximal side (P), so that the container (9) is in communication with the pumping chamber (3); It is characterized in that the fuel pump (1) includes an outlet module (20) having an outlet module body (21), the outlet module body being made of a single piece and accommodating the outlet valve (50) and the pressure relief valve (40) in the outlet module body, and the outlet module body defining the outlet channel (27) and the pressure relief channel (31), the outlet module body (21) being at least partially received in the container (9) and connected to the main body (2) in a fuel-tight manner.
2. The fuel pump according to claim 1, wherein: The outlet module body (21) comprises an external thread (22) which engages with an internal thread (11) of the main body (2) inside the container (9), the internal thread (11) and the external thread (22) being arranged concentrically around the outlet axis (A).
3. The fuel pump according to claim 2, wherein: The outlet module body (21) comprises a first sealing portion (24) which engages with a second sealing portion (12) of the body (2) inside the container (9), wherein at least one of the sealing portions (12, 24) comprises an annular blade element (25) which cuts into the other sealing portion (12, 24) to form a knife-edge seal.
4. A fuel pump according to any one of the preceding claims, wherein: The outlet module body (21) comprises a distal insertion opening (29) at the distal side (D), and during assembly, the pressure relief valve (40) is inserted into the outlet module body (21) through the distal insertion opening.
5. A fuel pump according to any one of the preceding claims, wherein: The pressure relief valve (40) includes a first seat member (41), a first valve member (42) and a first elastic member (43) for biasing the first valve member (42) against the first seat member (41), wherein the first seat member (41) is press-fitted into the outlet module body (21).
6. The fuel pump according to claim 5, wherein: The first seat member (41) comprises a through hole (41.1) extending from a pump side (46) communicating with the pumping chamber (3) to an outlet side (47) communicating with the outlet channel (27), the first valve member (42) having a head (42.1) for engaging the first seat member (41) from the pump side (46) in a closed position of the pressure relief valve (40) and an elongated shaft (42.2) passing through the through hole (41.1), the first elastic member (43) being arranged on the outlet side (47) and engaging with a stop member (44) rigidly connected to the shaft (42.2).
7. The fuel pump according to claim 6, wherein: The stop member (44) is press-fitted onto the shaft (42.2).
8. The fuel pump according to claim 6 or 7, wherein: The pressure relief valve (40) comprises a guide sleeve (45) which is mounted on the shaft (42.1) and is surrounded by the first elastic member (43), and the guide sleeve (45) extends from the first seat member (41) toward the stop member (44).
9. A fuel pump according to any one of the preceding claims, wherein: The outlet module body (21) comprises a proximal insertion opening (30) on the proximal side (P), and during assembly, the outlet valve (50) is inserted into the outlet module body (21) through the proximal insertion opening.
10. A fuel pump according to any one of the preceding claims, wherein: The outlet valve (50) includes a second seat member (51), a second valve member (52) and a second elastic member (53) for biasing the second valve member (52) against the second seat member (51), wherein the second seat member (51) is press-fitted into the outlet module body (21).
11. A fuel pump according to any one of the preceding claims, wherein: The outlet channel (27) comprises a proximal portion (27.1), a distal portion (27.3) and a plurality of intermediate portions (27.2), the outlet valve (50) being at least partially received in the proximal portion, the pressure relief valve (40) being at least partially received in the distal portion, and the intermediate portion connecting the proximal portion (27.1) and the distal portion (27.3), the outlet axis (A) passing through the proximal portion (27.1) and the distal portion (27.3), and the intermediate portion (27.2) deviating from the outlet axis (A).
12. A fuel pump according to any one of the preceding claims, wherein: At least one of the outlet valve (50), the pressure relief valve (40) and the outlet passage (27) is at least largely symmetrical with respect to the outlet axis (A).
13. A fuel pump according to any one of the preceding claims, wherein: The pressure relief passage (31) includes a main portion (31.1) adjacent to the pressure relief valve (40) and a plurality of branch portions (31.2) connected to the main portion (31.1), wherein the branch portions pass through the outlet module body (21) to the outside thereof and communicate with the pumping chamber (3).
14. An outlet module (20) for a fuel pump (1), the fuel pump (1) comprising a body (2), the body defining: a pumping chamber (3) having a pumping plunger (4) arranged to reciprocate within the pumping chamber (3), an inlet channel (5) at least indirectly connecting a low-pressure inlet of the fuel pump (1) to the pumping chamber (3), an inlet valve (6) being adapted to selectively allow a fluid to flow through the inlet channel (5) to the pumping chamber (3), and a container (9) open towards the distal side (D) and extending into the body (2) along an outlet axis (A) towards the proximal side (P) such that the container (9) communicates with the pumping chamber (3), It is characterized in that The outlet module (20) has an outlet module body (21) which is made of a single piece and in which an outlet valve (50) and a pressure relief valve (40) are received, and the outlet module body defines an outlet channel (27) and a pressure relief channel (31), the outlet module body (21) being adapted to be at least partially received in the container (9) and connected to the main body (2) in a fuel-tight manner, such that, - the outlet channel (27) at least indirectly connects the pumping chamber (3) to a high-pressure outlet (28) of the fuel pump (1), the outlet valve (50) being adapted to selectively allow fluid to flow through the outlet channel (27) to the outlet (28); and The pressure relief channel (31) connects the outlet channel (27) downstream of the outlet valve (50) to the pumping chamber (3), and the pressure relief valve (40) is suitable for selectively allowing fluid to flow through the pressure relief channel (31) to the pumping chamber (3).