Pump

Abstract

The invention relates to a pump (1) comprising a check valve (10) extending along a valve axis (A) from a proximal side (P) to a distal side (D), the check valve (10) comprising:-an axially extending valve bore (11) defined within a pump body (2) of the pump (1) and having an inner surface (12),-a seat member (15) defining an axially extending valve passage (17) and having a mounting portion (15.6) and a seat portion (15.2), and a mounting portion (15.6) which is press-fitted into the valve bore (11) such that the mounting portion engages the inner surface (12), and a seat portion (15.2) which is arranged at a proximal end with respect to the mounting portion (15.6), the seat portion (15.2) defining a seat surface (15.1) around a proximal end opening (18) of the valve passage (17), a pilot radius rp, which is a maximum radius of said seat portion (15.2), is at least 95% but less than 100% of a valve bore radius rb of the valve bore (11), such that the seat portion (15.2) is not in contact with the inner surface (12), and-a valve member (20) movable relative to the seat member (15) and engaging the seat surface (15.1) in a closed position to close the valve passage (17). In order to improve the reliability of a safety valve in a fuel pump, the invention provides a groove portion (15.5) axially interposed between the seat portion (15.2) and the mounting portion (15.6), the groove portion (15.5) defining a radially inwardly extending groove (16) between the seat portion (15.2) and the mounting portion (15.6), the groove portion (15.5) is at least partially radially spaced from the inner surface (12) by the groove (16).

Description

Technical Field

[0001] The invention relates to a pump and a check valve for the pump. Background Art

[0002] Fuel systems in modern internal combustion engines fueled by gasoline, especially for the automotive market, mainly 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 in the fuel tank. The low-pressure fuel pump supplies the fuel to a high-pressure fuel pump (also known as a GDi pump), which usually includes a pumping plunger that is reciprocated by the camshaft of the internal combustion engine. During the intake stroke, the fuel is sucked into the pumping chamber, and in the subsequent pumping stroke, the pumping plunger further pressurizes the fuel so that it can be supplied to the fuel injector at high pressure. In order to avoid backflow from the fuel rail into the pumping chamber, the fuel pump includes an outlet valve, which is arranged in the outlet channel on the high-pressure side of the pumping chamber.

[0003] For safe operation, the GDi pump also includes a safety channel with an embedded safety 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). Such a safety valve usually includes a fixed seat member and a movable valve member, which is biased against the seat member into a closed position. The seat surface of the seat member needs to have a shape corresponding to the shape of the valve member to avoid any unnecessary leakage. Known designs provide that the seat member is press-fitted into a hole or channel in the body of the fuel pump. This press-fit causes deformation of the seat member, which may also affect the seat surface. Even if the shape of the seat surface is precise enough before the press-fit operation, this may no longer apply to the valve in the installed state in the pump.

[0004] Purpose of the Invention

[0005] The object of the present invention is to improve the reliability of a safety valve in a fuel pump.

[0006] This object is achieved by a pump according to claim 1 and a non-return valve according to claim 15 . Summary of the invention

[0007] The present invention relates to a pump comprising a check valve extending from a proximal side to a distal side along a valve axis. Typically, the pump is adapted to deliver fluid from at least one inlet to at least one outlet by the action of at least one pumping element (e.g., a plunger). Preferably, the pump is also adapted to increase fluid pressure at at least one outlet relative to at least one inlet. Typically, the pump may include a plurality of valves, some of which will be discussed below. The check valve is designed to allow fluid to flow in only one direction while preventing fluid from flowing in the opposite direction. It extends along a valve axis defining an axial direction and may be at least partially symmetrical relative to the valve axis. With respect to the valve axis, a proximal side and a distal side may be defined. As will be explained below, the distal side may be in fluid communication with the outlet of the pump, but the present invention is not limited to this configuration.

[0008] The check valve comprises an axially extending valve hole, which is defined in the pump body of the pump and has an inner surface. The valve hole is usually arranged parallel to the valve axis and symmetrical with respect to it. It is usually at least partially cylindrical, that is, it has a circular cross-section. The term "hole" should not be interpreted as that the hole must be made by drilling or other chip removal processes. It is arranged inside the pump body of the pump. The pump body can be made of a single piece, or it can include several connected elements. It can be at least partially the same as the housing of the pump. The valve hole can also be arranged in a dedicated element as part of a valve assembly or valve module. Such an element can be a sleeve that forms the valve hole and can be connected to other elements of the pump body. The inner surface defines the valve hole. It is an "inner" surface because it faces inward toward the cavity of the valve hole.

[0009] The check valve further includes a seat member defining an axially extending valve passage and having a mounting portion and a seat portion, the mounting portion being press-fitted into the valve hole so that it engages with the inner surface, the seat portion being arranged proximally relative to the mounting portion, the seat portion defining a seat surface surrounding a proximal opening of the valve passage, wherein a pilot radius r being a maximum radius of the seat portion p is the valve hole radius r of the valve hole bAt least 95% but less than 100% of the inner surface of the seat member, so that the seat portion does not contact the inner surface. The valve channel is defined inside the seat member, that is, it passes through the seat member. It extends axially and is usually arranged along the valve axis. In addition, it is usually symmetrical with respect to the valve axis. The seat member has a mounting portion that is press-fitted into the valve hole. Therefore, the seat member is manufactured so that the outer dimension of the mounting portion is larger than the inner dimension of the valve hole, so that the seat member can only be inserted into the valve hole under plastic and / or elastic deformation. This also ensures that the seat member engages with the inner surface. For example, the mounting portion radius of the mounting portion can be larger than the valve hole radius. During the press-fit operation, the seat member moves toward the proximal side. When the press-fit is completed, the seat member is held in place by the friction between the mounting portion and the inner surface of the valve hole. The seat portion of the seat member is arranged close to (that is, on the proximal side) the mounting portion. Therefore, when the seat member is inserted into the valve hole, the seat portion enters the valve hole before the mounting portion. The seat portion defines a seat surface around the proximal opening of the valve channel. It can also be said that the seat portion includes the seat surface, i.e. it is a part of the entire surface of the seat portion (and the seat member). The seat surface is arranged around the opening on the proximal side of the valve channel. As with the valve channel, the opening is usually symmetrical with respect to the valve axis. The same applies to the seat surface, which is usually annular. The pilot radius r as the maximum radius of the seat portion p is the valve hole radius r of the valve hole b At least 95% but less than 100% of the inner surface. The term "pilot radius" indicates that one function of the seat portion is generally to pilot (i.e. guide) the seat member during its insertion into the valve hole. The portion of the seat portion having the pilot radius is the widest portion. However, the pilot radius is still smaller than the valve hole radius of the valve hole. Therefore, the seat portion can be inserted into the valve hole without the need for press fitting or any other deformation process. Therefore, the seat portion does not contact the inner surface. However, since the pilot radius is at least 95% of the valve hole radius, once the seat portion has been inserted into the valve hole, the position of the seat member perpendicular to the valve axis is clearly defined. The pilot radius can be at least 97% or at least 98% of the valve hole radius.

[0010] The check valve further comprises a valve member which is movable relative to the seat member and which engages with the seat surface in the closed position to close the valve passage. The valve member may be a ball, a needle or any other suitable element for engaging the seat surface. It may also comprise several pieces. In the closed position of the check valve, the valve member sealingly engages the seat surface, thereby preventing any fluid from flowing through the valve passage. The valve member and the seat member cooperate to provide the valve mechanism, wherein the seat member represents the stationary part of the valve mechanism and the valve member represents the movable part. The valve member is usually biased against the seat member, i.e. into the closed position. Typically, the check valve comprises a spring member for biasing the valve member against the seat surface. Such a spring member acts directly or indirectly between the seat member and the valve member. By the action of the spring member, the valve member is biased against the seat member into the closed position of the check valve. Therefore, the force acting on the valve member due to the pressure difference between the proximal side and the distal side must overcome the biasing force to move the valve member to the open position, thereby opening the check valve.

[0011] According to the present invention, a groove portion is axially interposed between the seat portion and the mounting portion, the groove portion defining a groove extending radially inward between the seat portion and the mounting portion, so that the groove portion is at least partially radially spaced apart from the inner surface by the groove. Therefore, the mounting portion and the seat portion are not arranged axially adjacent to each other, but a groove portion is arranged between them. The groove portion defines a groove extending radially inward. Therefore, the surface of the seat member is radially set back relative to the mounting portion and the seat portion. Of course, the groove also extends axially and tangentially. The groove portion is at least partially spaced apart from the inner surface by the groove relative to the radial direction. Therefore, at least a portion of the groove portion does not contact the inner surface. The groove portion can define a plurality of grooves, but usually it defines a single groove. It can be said that the groove separates the mounting portion and the seat portion. This results in a mechanical disengagement of the seat portion from the mounting portion. Therefore, when the mounting portion is deformed in a press-fit operation, the seat portion is not deformed or is only minimally deformed. Therefore, the expected shape of the seat surface is maintained, thereby producing a reliable sealing effect. Another benefit of the design of the seat member of the present invention is related to the specific size of the pilot radius, which is sufficiently reduced to allow mechanical decoupling of the mounting portion and the seat portion, but still represents the valve bore radius r b This limits the tilting of the seat member during the press-fit process.

[0012] Although the present invention is not limited to this application, preferably, the check valve is a safety valve and the pump is a fuel pump with a pumping chamber connected to a high-pressure outlet via an outlet valve, wherein the distal side is in fluid communication with the high-pressure outlet and the proximal side is in fluid communication with a position upstream of the outlet valve via a safety passage. In at least some embodiments, the fuel pump may be referred to as a high-pressure fuel pump or a gasoline direct injection fuel pump (GDi pump). Typically, fuel from a fuel tank is supplied to the high-pressure fuel pump by a low-pressure fuel pump at a relatively low pressure. The high-pressure fuel pump comprises a pumping chamber which typically has a pumping plunger. Through the action of the pumping plunger, fuel can be sucked into the pumping chamber during an intake stroke and can subsequently be pressurized and discharged from the pumping chamber during a compression stroke or a pumping stroke. Thus, the fuel enters the pumping chamber at a low pressure and leaves the pumping chamber at a high pressure. The pumping plunger may be electrically operated or may be mechanically linked to an engine, in particular to an internal combustion engine to which the fuel pump supplies fuel. For example, the pumping plunger may be linked to a camshaft of the engine. 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. 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 may simply be referred to as "outlet", while the term "high pressure" indicates that the fuel leaving the outlet has been pressurized by the fuel pump. In the assembled state, the outlet may 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. In order to avoid backflow, an outlet valve is interposed between the pump and the outlet. The outlet valve is adapted to selectively enable a fluid to flow through the outlet channel toward the pumping chamber. The outlet valve is a one-way valve which prevents the fuel from flowing in the opposite direction, i.e. toward the pumping chamber. In addition, the outlet valve can only enable the fluid to flow toward the outlet if a certain opening pressure is exceeded. The outlet valve may be arranged in the outlet passage, for example close to the outlet, close to the pumping chamber or somewhere in between.

[0013] For safety reasons, the pump includes a safety valve to avoid any overpressure that could cause the pump or other components to burst. The distal side is in fluid communication with the outlet. If the opening pressure of the safety valve is exceeded, the valve member moves to open the valve member channel and the fuel flows to the proximal side. The proximal side is connected to a position upstream of the outlet valve (e.g., the pumping chamber or the low-pressure inlet of the pump) via a safety channel. It can be said that the safety channel bypasses / bypasses the outlet valve, while the safety valve controls the fluid flowing through the safety channel. Therefore, fuel can be released from the outlet channel through the pressure relief channel, for example into the pumping chamber. The function of the safety channel is to prevent overpressure in the outlet channel and / or, for example, a fuel rail connected to the outlet channel. The safety valve can only allow the fuel to flow toward the pumping chamber when a certain opening pressure is exceeded. In other words, if the pressure difference between the outlet channel and the pumping chamber is high enough, the safety valve opens to release the fuel from the outlet channel through the safety channel.

[0014] The pump of the present invention is typically a high-pressure pump. In particular, the pump may be adapted to generate a pressure of at least 200 bar on the distal side of the non-return valve. The pressure may even be higher, for example, at least 300 bar, at least 400 bar. This is typically the case for automotive fuel pumps. Although the net force acting on the non-return valve and its components also depends on the pressure on the proximal side, the above pressures also typically mean that the non-return valve must withstand considerable axial forces. For example, the press-fit connection between the seat member and the valve bore needs to be tight enough to withstand these forces. This in turn means that in the absence of the grooves used in the design of the present invention, the risk of deformation of the seat portion will increase.

[0015] Very preferably, the groove extends circumferentially around the valve axis. In other words, the shape of the groove is annular and generally symmetrical about the valve axis. Either of the shapes of the groove, such as a groove extending over only a portion of the circumference, may result in an asymmetrical coupling between the mounting portion and the seat portion, which in turn may result in unwanted deformation of the seat portion.

[0016] In one embodiment, the axial groove length l of the groove is g The axial seat length l of the seat portion sp The groove is therefore not longer than the seat portion, but still has a comparable length. This ratio, which may preferably be between 60% and 80%, affects the disengagement of the seat portion from the mounting portion in two ways. On the one hand, a (axially) longer groove increases the disengagement effect. On the other hand, a longer seat portion is generally more stable than a shorter seat portion. However, the groove length l gand the seat portion length l sp Both increase the overall length of the seat member (which is limited by the size and geometry of the pump) and it is therefore desirable to find a preferred ratio between these two lengths.

[0017] On the one hand, it is beneficial if the groove is relatively deep and extends far inwards in the radial direction, since this helps to decouple the seat portion from any deformation of the mounting portion. On the other hand, if the groove is too deep, the structural and mechanical rigidity of the seat member as a whole may be compromised. Preferably, the minimum groove portion radius r of the groove portion is g At the pilot radius r p . More specifically, the ratio may be between 45% and 60%. The minimum groove portion radius (or simply: the groove portion radius) defines the innermost extent of the groove, or the bottom of the groove. On the other hand, the pilot radius defines the "height" of the seat portion located on the proximal side of the groove. It will be understood that the groove portion radius may also depend on the radius of the valve channel, since the difference between these radii is equal to the material thickness radially inside the groove. Preferably, this thickness may be between 15% and 35% of the pilot radius, or between 20% and 30%.

[0018] Preferably, the groove is relatively short and sharply defined. Thus, one embodiment provides that the groove is delimited by side walls facing each other along the valve axis, each side wall being arranged at an angle of at least 75° relative to the valve axis. One side wall is arranged on the proximal side of the groove and the other on the distal side. They may be arranged at an angle of at least 80° or at least 85° relative to the valve axis. In particular, they may be perpendicular to the valve axis.

[0019] Preferably, the seat portion includes a tapered portion and defines a pilot radius r pA pilot portion, the tapered portion is arranged at the proximal end relative to the pilot portion and tapers toward the proximal side. In some embodiments, there is a smooth transition between the pilot portion and the tapered portion, that is, they may not have a clear boundary between each other. In any case, the pilot portion defines the pilot radius, that is, it has the maximum radius of the seat portion. On the other hand, the tapered portion has a radius smaller than the pilot radius and decreases toward the proximal side. The tapered portion tapers in a tapered manner, which clearly includes a truncated cone and a slight deviation from a strict (truncated) cone, such as a nonlinear decrease in the radius along the axial direction. Although these nomenclatures are used herein, during the insertion of the seat member into the valve hole, not only the pilot portion but also the tapered portion can be used to guide the seat member. The tapered shape of the tapered portion can promote this function. Since its radius is smaller on the proximal side and increases toward the distal side, it helps to guide the seat member into the valve hole, for example, in the event of some initial misalignment.

[0020] The cone angle α of the conical portion may be between 35° and 50°, or may be between 40° and 45°. However, in some embodiments, the cone angle may be outside this specified range. This also includes embodiments in which the conical portion is not a strict (truncated) cone, so the cone angle is not constant but has some variation.

[0021] In some embodiments, the seat member may be elongated in the axial direction, ie, its length may be much greater than its diameter. However, in a preferred embodiment, the axial seat member length l of the seat member is sm Smaller than the valve hole radius r b 200% of the diameter. Since the seat member is press-fitted into the valve hole, its maximum outer radius corresponds to the valve hole radius. Before the seat member is press-fitted into the valve hole, its maximum radius (the above-mentioned mounting portion radius) is slightly larger than the valve hole radius, but this difference is usually less than 1%. In this embodiment, the length of the seat member in the axial direction is less than the diameter, that is, less than twice the radius. It can also be said that the seat member is relatively short or compact in the axial direction. More specifically, the seat member length l sm can be smaller than the valve hole radius r b 170%, or even less than 150%.

[0022] One embodiment provides that the mounting portion has a press-fit portion engaging the inner surface of the valve hole and a tapered portion, which is arranged proximally relative to the press-fit portion and adjacent to the groove portion, the tapered portion having a smaller radius than the press-fit portion. In other words, the mounting portion does not have a single, constant outer diameter, but rather it tapers toward the groove portion. The press-fit portion of the mounting portion has a radius (the mounting portion radius) that is generally constant and corresponds to the radius of the valve hole, i.e., the radius is larger before the seat member is press-fitted into the valve hole. On the other hand, the tapered portion has a reduced radius, which may also vary along the length of the tapered portion. In some embodiments, the shape of the tapered portion may be conical, but it has a relatively small cone angle, for example between 5° and 50°. Although the seat portion with its pilot radius plays an important role in the centering of the seat member inside the valve hole, this function can be supplemented by the tapered portion. Typically, the axial length of the tapered portion corresponds to between 10% and 25% of the length of the entire mounting portion.

[0023] Typically, the seat portion corresponds to only a small portion (i.e., less than 50%) of the entire length of the seat member relative to the axial direction. On the other hand, in order to provide sufficient structural stability for the seat portion, it should not be designed too short. In a preferred embodiment, the seat portion length l sp In the seat member length l sm More specifically, the percentage may be between 15% and 25%. It will be appreciated that the exact value may depend on the absolute length of the seat member and the size of the recess. In the case of a deeper recess, increasing the length of the seat portion may be helpful to ensure adequate stability.

[0024] Furthermore, the mechanical stability of the seat member and its resistance to deformation depends on the relationship between the valve channel and the valve hole. For example, if the valve channel has a radius that is not much smaller than the valve hole, this will make the seat member "thin-walled" and thus less stable. On the other hand, the valve channel should not be too narrow in order to provide a sufficiently wide flow path when the check valve is open. Preferably, the channel radius r of the valve channel is c The valve hole radius r b More specifically, it may be between 20% and 30% of the radius of the valve hole.

[0025] In one embodiment, the channel radius of the valve member channel is constant. Alternatively, the valve member channel may have a radius that varies along the axial direction. According to one such embodiment, the valve member channel has a proximal first channel section having a second channel radius r relative to a distal second channel section. c2 Reduced first channel radius r c1 , the proximal first channel section extends from the axial position of the seat portion to the axial position of the mounting portion. Although only the first channel section and the second channel section are mentioned, more channel sections are possible. The first channel section is arranged at the proximal end, while the second channel section is arranged at the distal end. The first channel section has a smaller radius than the second channel section. This results in an increase in the material thickness of the radially outer side of the first channel section, that is, the structure of the seat member is strengthened in this area. Since the first channel section extends from the axial position of the seat portion to the axial position of the mounting portion, it is also radially arranged inside the groove portion. Therefore, the groove can be designed to be deeper without excessively weakening the seat member in this area. On the other hand, the second channel section is designed to be wider, which reduces the flow resistance and also reduces the overall material volume of the check valve.

[0026] The invention also relates to a non-return valve for a pump, which extends along a valve axis from a proximal side to a distal side and comprises, in an assembled state:

[0027] - an axially extending valve bore, the valve bore being defined within the pump body and having an inner surface,

[0028] a seat member defining an axially extending valve passage and having a mounting portion and a seat portion, the mounting portion being press-fitted into the valve bore so that it engages the inner surface, the seat portion being arranged proximally relative to the mounting portion, the seat portion defining a seat surface around a proximal opening of the valve passage, wherein a pilot radius r being a maximum radius of the seat portion p is the valve hole radius r of the valve hole b at least 95% but less than 100% such that the seat portion is not in contact with the inner surface, and

[0029] a valve member movable relative to the seat member and engaging the seat surface in a closed position to close the valve passage,

[0030] A groove portion is axially interposed between the seat portion and the mounting portion, the groove portion defining a radially inwardly extending groove between the seat portion and the mounting portion such that the groove portion is at least partially radially spaced apart from the inner surface by the groove.

[0031] All these terms have been explained above with respect to the pump of the present invention and will therefore not be explained again. Preferred embodiments of the check valve of the present invention correspond to the embodiments of the pump of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0033] Figure 1 is a cross-sectional view of a fuel pump of the present invention;

[0034] Figure 2 yes Figure 1 A detailed cross-sectional view of a fuel pump with a safety valve of the present invention;

[0035] Figure 3 is used for Figure 2 A side view of a first embodiment of a component of a safety valve;

[0036] Figure 4 yes Figure 3 A three-dimensional view of a seat member;

[0037] Figure 5 yes Figure 3 a cross-sectional side view of a seat member; and

[0038] Figure 6 It is a cross-sectional side view of the second embodiment of the seat member. DETAILED DESCRIPTION

[0039] Figure 1 A fuel pump 1 according to the invention is shown. The general structure and operating principle of the fuel pump 1 are generally well known and will therefore only be briefly described here. The fuel pump 1 is generally part of a fuel system (not shown) of an internal combustion engine, which generally includes a fuel tank, which contains a certain volume of fuel to be supplied to 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.

[0040] The fuel pump 1 comprises a pump body 2 having various components, most of which are made of metal (e.g., stainless steel). The pump body 2 defines a pumping chamber 3 having a pumping plunger 4, which is adapted to reciprocate within the pumping chamber 3 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 having an inlet valve 6. The inlet passage 5 is connected to a low-pressure inlet (not visible) of the fuel pump 1, via which the fuel pump 1 can be connected to the above-mentioned low-pressure pump. Fuel enters the pump through the low-pressure inlet and is guided to the inlet passage via a damping volume 8, which is arranged in a damping cup mounted to the pump body 2.

[0041] The pump body 2 also defines an outlet passage 30 having an outlet valve (not shown) which connects the pumping chamber 3 to a high-pressure outlet 31 of the fuel pump 1. In addition, the pump body 2 defines a safety passage 25 having a safety valve 10. The outlet valve is a check valve which enables the fuel to flow from the pumping chamber 3 to the outlet 31 if the pressure in the pumping chamber 3 exceeds the pressure in the outlet passage 30. The safety valve 10 is also a check valve which enables the fluid to flow back from the outlet passage 30 to the pumping chamber 3 through the safety passage 25 if the pressure in the outlet passage 30 exceeds the pressure in the pumping chamber 3 and the difference is greater than a defined opening pressure.

[0042] 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 and the outlet passage 30. The fuel can then be supplied to a fuel rail connected to the above-mentioned injectors via the outlet 31. During the compression stroke, the inlet valve 6 prevents backflow through the inlet passage 5. If at any time the pressure differential between the outlet passage 30 and the pumping chamber 3 exceeds a predetermined opening pressure, the safety valve 10 opens to release the fuel from the outlet passage 30 through the safety passage 25 into the pumping chamber 3, thereby preventing possible damage to any components downstream of the fuel pump 1.

[0043] Now refer to Figures 2 to 5 The details of the safety valve 10 are discussed. The safety valve 10 includes a valve hole 11, which is part of the safety passage 25 or directly connected to the safety passage 25. The valve hole 11 is aligned along a valve axis A defining an axial direction and has a valve hole radius r in this embodiment. b The main elements of the valve mechanism are the seat member 15 and the valve member 20. The seat member 15 is stationary and is connected to the pump body 2 by press-fitting it into the valve hole 11. On the other hand, the valve member 20 is axially movable and is biased against the seat member 15 by the spring member 21. Here, the valve member is spherical. Specifically, in Figure 1and Figure 2 In the closed position shown in FIG. , the valve member 20 engages with the seat surface 15.1 of the seat member 15. Figures 3 to 5 As can be seen in FIG. 1 , the seat surface 15.1 has an overall annular shape and is arranged around a proximal opening 18 of a valve channel 17 passing through the seat member 15. The valve channel 18 is symmetrical about the valve axis A and has a channel radius r c In this exemplary embodiment, the channel radius r c is 0.58 mm, which is consistent with the valve hole radius r b In other embodiments, the ratio may be different, for example between 15% and 35%.

[0044] Along the axial direction A, three different parts of the seat member 15 can be distinguished. The seat surface 15.1 is arranged on a seat portion 15.2 which is not in contact with the inner surface 12 of the valve hole 11, while the mounting portion 15.6 engages with the inner surface 12 by a press fit. The recessed portion 15.5 is interposed between the seat portion 15.2 and the mounting portion 15.6. It defines a single recess 16 extending radially inwardly. The recessed portion 15.5 is radially spaced apart from the inner surface by means of the recess.

[0045] The shape and dimensions of the seat member 15 and its parts 15.2, 15.5, 15.6 will now be described in more detail. It should be understood that these dimensions are exemplary and may be modified depending on a number of factors (e.g., the overall size and performance of the fuel pump 1). The axial seat member length l of the seat member 15 is sm 3.6mm, which corresponds to a length smaller than the valve hole radius r b 200%, in this case 144%. The seat portion 15.2 has a total axial seat portion length l of 0.7 mm. sp , which is approximately the seat member length l sm 19% of the groove 16, but may also be between 10% and 30%. It comprises a pilot portion 15.4 and a tapered portion 15.3, the pilot portion being arranged adjacent to the groove 16 and defining a pilot radius r of 2.46 mm. p , which is arranged close to the leading portion 15.4 and tapers conically towards the proximal side P. Specifically, the tapered portion 15.3 has a truncated cone shape with a cone angle α of about 42°, which may be between 35° and 50°. p Only larger than the valve hole radius r b A little smaller (this corresponds to 98% thereof), the pilot portion 15 . 4 therefore facilitates the piloting or guiding of the seat member 15 during its insertion into the valve bore 11 .

[0046] The mounting portion 15.6 has a press-fit portion 15.7 and a tapered portion 15.8. In its undeformed state, i.e. before being inserted into the valve hole, the mounting portion radius r of the press-fit portion 15.7 is b 2.52mm, which is slightly larger than the valve hole radius r b . Thus, after being inserted into the valve hole 11, the press-fit portion 15.7 engages with the inner surface 12 of the valve hole 11. A tapered portion 15.8 is arranged close to the press-fit portion 15.7 and adjacent to the groove portion 15.5, the tapered portion having a smaller radius than the press-fit portion 15.7. Thus, it remains out of contact with the inner surface 12, but can be supplemented by the pilot portion 15.4 in a guiding function during the insertion and press-fitting process.

[0047] In this embodiment, the groove 16 extends circumferentially around the valve axis A and has an axial groove length l of 0.5 mm. g , which is related to the seat length l sp However, this ratio may be different, for example between 40% and 100%. The minimum groove portion radius r of the groove portion 15.5 is g is 1.2 mm, which is consistent with the pilot radius r p Alternatively, the ratio may be between, for example, 40% and 70%. The radial "depth" of the groove 16 is about 1.27 mm. The groove 16 is delimited by side walls 15.9 facing each other along the valve axis A, each side wall 15.9 being perpendicular to the valve axis A.

[0048] By the presence of the groove 16, the deformation of the seat portion 15.6 and the mounting portion 15.2 during the press fit is mechanically decoupled. Thus, the precise shape of the seat surface 15.1 is maintained, which is necessary to maintain the sealing engagement of the valve member 20 with the seat surface 15.1. Considering the channel radius r c and the minimum groove radius r g The remaining material thickness in the radial inner part of the groove 16 is about 0.61 mm, which is sufficient to maintain the overall structural stability of the seat member 15.

[0049] Figure 6 A second embodiment of a seat member 15 for a safety valve 10 is shown. This embodiment is largely identical to the first embodiment, except for minor differences which will not be discussed here. However, the valve channel 17 does not have a constant radius. Instead, it has a proximal first channel section 17.1 having a first channel radius r c1 , the first channel radius is relative to the second channel radius r of the distal second channel section 17.2 c2 In this embodiment, the radius of the first channel r c1 is 0.58 mm, and the radius of the second channel rc2 The first channel section 17.1 extends from the axial position of the seat portion 15.2 along the groove portion 15.5 to the axial position of the mounting portion 15.6. Therefore, the seat member 15 is strengthened near the groove 16, which helps to prevent deformation of the seat portion 15.2. Possibly, the depth of the groove 16 can even be increased, that is, the groove portion radius r g can be reduced without destabilizing the seat member 15 in an undesirable manner. On the other hand, the larger second channel radius r c2 The flow resistance inside the valve passage 17 is reduced, and the overall volume of the seat member 15 is reduced.

[0050] List of reference numerals:

[0051] 1 Fuel pump

[0052] 2 Pump body

[0053] 3 Pumping chamber

[0054] 4 Pumping plunger

[0055] 5 Entryway

[0056] 6 Inlet valve

[0057] 8 Damping volume

[0058] 10 Safety valve

[0059] 11 Valve hole

[0060] 12 Inner surface

[0061] 15 Seat Components

[0062] 15.1 Seat surface

[0063] 15.2 Seat

[0064] 15.3 Conical section

[0065] 15.4 Preliminary part

[0066] 15.5 Groove section

[0067] 15.6 Installation

[0068] 15.7 Press-fit section

[0069] 15.8 Conical section

[0070] 15.9 Sidewalls

[0071] 16 grooves

[0072] 17 Valve channel

[0073] 17.1 First channel section

[0074] 17.2 Second channel section

[0075] 18 Proximal opening

[0076] 20 Valve member

[0077] 21 Spring member

[0078] 25 Safe Passage

[0079] 30 Exit Channel

[0080] 31 Exit

[0081] A Valve axis

[0082] D Distal side

[0083] L g Groove length

[0084] L sm Seat component length

[0085] L sp Seat length

[0086] P proximal side

[0087] r b Valve hole radius

[0088] r c Channel radius

[0089] r c1 First channel radius

[0090] r c2 Second channel radius

[0091] r g Groove radius

[0092] r m Installation section radius

[0093] r p Pilot radius

[0094] α cone angle

Claims

1. A pump (1), comprising a check valve (10) extending along a valve axis (A) from a proximal side (P) to a distal side (D), the check valve (10) comprising: - an axially extending valve bore (11), which is defined in a pump body (2) of the pump (1) and has an inner surface (12), - a seat member (15) defining an axially extending valve channel (17) and having a mounting portion (15.6) and a seat portion (15.2), the mounting portion being press-fitted into the valve bore (11) so that the mounting portion engages the inner surface (12), the seat portion (15.2) being arranged proximally relative to the mounting portion (156), the seat portion (15.2) defining a seat surface (15.1) around a proximal opening (18) of the valve channel (17), wherein a pilot radius r being a maximum radius of the seat portion (15.2) p is the valve hole radius r of the valve hole (11) b at least 95% but less than 100% of the inner surface (12), so that the seat portion (15.2) is not in contact with the inner surface (12), and - a valve member (20) which is movable relative to the seat member (15) and which engages the seat surface (15.1) in a closed position to close the valve channel (17), The groove portion (15.5) is axially inserted between the seat portion (15.2) and the mounting portion (15.6), and the groove portion (15.5) defines a radially inwardly extending groove (16) between the seat portion (15.2) and the mounting portion (15.6), so that the groove portion (15.5) is at least partially radially spaced apart from the inner surface (12) by the groove (16).

2. The pump according to claim 1, wherein The check valve (10) is a safety valve, and the pump (1) is a fuel pump having a pumping chamber (3) connected to a high-pressure outlet (31) via an outlet valve, wherein the distal side (D) is in fluid communication with the high-pressure outlet (31), and the proximal side (P) is in fluid communication with a position upstream of the outlet valve via a safety passage (25).

3. Pump according to any of the preceding claims, adapted to generate a pressure of at least 200 bar at the distal side (D) of the non-return valve (10).

4. A pump according to any one of the preceding claims, wherein The groove (16) extends circumferentially around the valve axis (A).

5. A pump according to any one of the preceding claims, wherein The axial groove length l of the groove (16) g The axial seat length l of the seat portion (15.2) sp between 40% and 100%.

6. A fuel pump according to any one of the preceding claims, wherein: The minimum groove radius r of the groove portion (15.5) g At the pilot radius r p between 40% and 70%.

7. A pump according to any one of the preceding claims, wherein The groove (16) is delimited by side walls (15.9) facing each other along the valve axis (A), each side wall (15.9) being arranged at an angle of at least 75° relative to the valve axis (A).

8. A pump according to any one of the preceding claims, wherein The seat portion (15.2) comprises a pilot portion (15.4) and a tapered portion (15.3), wherein the pilot portion defines the pilot radius r p , the tapered portion is arranged close to the leading portion (15.4) and tapers conically toward the proximal side (P).

9. A pump according to any one of the preceding claims, wherein The cone angle α of the conical portion (15.3) is between 35° and 50°.

10. A pump according to any one of the preceding claims, wherein The axial seat member length l of the seat member (15) sm Smaller than the valve hole radius r b 200% of.

11. A pump according to any one of the preceding claims, wherein The mounting portion (15.6) has a press-fit portion (15.7) and a tapered portion (15.8), wherein the press-fit portion engages with the inner surface (12) of the valve hole (11), the tapered portion is arranged close to the press-fit portion (15.7) and adjacent to the groove portion (15.5), and the tapered portion (15.8) has a smaller radius than the press-fit portion (15.7).

12. A fuel pump according to any one of the preceding claims, wherein: The seat portion length l sp In the seat member length l sm between 10% and 30%.

13. A pump according to any one of the preceding claims, wherein The channel radius r of the valve channel (17) c The valve hole radius r b between 15% and 35%.

14. A pump according to any one of the preceding claims, wherein The valve member channel (17) has a proximal first channel section (17.1), the first channel radius of the proximal first channel section being r c1 The second channel radius r relative to the distal second channel section (17.2) c2 The first channel section (17.1) extends from an axial position of the seat portion (15.2) to an axial position of the mounting portion (15.6).

15. A non-return valve (10) for a pump (1), the non-return valve (10) extending along a valve axis (A) from a proximal side (P) to a distal side (D) and comprising, in an assembled state: - an axially extending valve bore (1), the valve bore being defined in a pump body (2) of the pump (1) and having an inner surface (12), - a seat member (15) defining an axially extending valve channel (17) and having a mounting portion (15.6) and a seat portion (15.2), the mounting portion being press-fitted into the valve bore (11) so that the mounting portion engages the inner surface (12), the seat portion (15.2) being arranged proximally relative to the mounting portion (15.6), the seat portion (15.2) defining a seat surface (15.1) around a proximal opening (18) of the valve channel (17), wherein a pilot radius r being a maximum radius of the seat portion (15.2) p is the valve hole radius r of the valve hole (11) b at least 95% but less than 100% of the inner surface (12), so that the seat portion (15.2) is not in contact with the inner surface (12), and a valve member (20) which is movable relative to the seat member (15) and which engages the seat surface (15.1) in a closed position to close the valve passage (17), The groove portion (15.5) is axially inserted between the seat portion (15.2) and the mounting portion (15.6), and the groove portion (15.5) defines a radially inwardly extending groove (16) between the seat portion (15.2) and the mounting portion (15.6), so that the groove portion (15.5) is at least partially radially spaced apart from the inner surface (12) by the groove (16).

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