Fuel injector
By setting a partition contact surface in the housing of the fuel injector, the hydraulic resistance is reduced and the impact force is evenly distributed, the problem of the adhesion effect of the fuel injector is solved, and its reliability and life are improved.
Patent Information
- Application Number
- CN202380037714.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-23
- Filing Date
- 2023-05-22
- Publication Date
- 2024-12-13
Smart Images
Figure CN119137366A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a fuel injector and to an engine system. Background Art
[0002] Fuel injectors are used in combustion engines to inject fuel, for example, into a flow channel of an intake manifold in front of a cylinder intake valve, or directly into a combustion chamber of an engine cylinder. According to a known design, a pivot and an armature are arranged in an injector housing. The pivot is movable between a closed position, in which the pivot (or a ball fixed to the pivot) closes the nozzle at one end of the injector housing, and an open position, in which the pivot moves away from the nozzle, thereby enabling fuel injection. The pivot passes through a through hole in the armature, and the armature is movable in the injector housing. In order to open the injector nozzle, a magnetic field is generated by a magnetic coil, which is enhanced by a pole piece arranged at the proximal end of the armature (i.e., away from the nozzle end of the injector), and moves the armature away from the nozzle. The armature has a contact surface that engages with a corresponding contact surface of the pivot to move the pivot away from the nozzle. Typically, a first spring is arranged to bias the pivot toward the nozzle, and a second spring is arranged to bias the armature toward the nozzle.
[0003] During its movement, the armature alternately contacts and separates from the pole piece, the pivot, etc. Since all these parts are inside the injector housing filled with fuel, the considerable hydraulic contact forces hinder the separation process, resulting in the so-called sticking effect. This in turn makes it difficult to ensure a reliable and repeatable movement cycle of the fuel injector. Generally, this sticking effect increases with the increase of the contact surface area. Therefore, it is known to minimize this area by providing, for example, an annular surface with a minimum width, so that it is essentially one-dimensional. However, such a small area increases the stress on the contact surface during each contact, thereby shortening the life of the injector. In addition, with such a narrow contact surface, the contact process may vary significantly from one contact to the next ("from one time to the next"), i.e., the repeatability is impaired.
[0004] Technical issues
[0005] It is therefore an object of the present invention to provide a fuel injector having reliable operation and a long life.
[0006] This problem is solved by a fuel injector according to claim 1 and an engine system according to claim 14 . Summary of the invention
[0007] The present invention provides a fuel injector. Specifically, this is a fuel injector for a combustion engine. It can be configured for direct injection or indirect injection.
[0008] The fuel injector comprises a housing extending from a proximal end to a distal end along an injector axis and having a nozzle at the distal end. One of the main functions of the housing is to contain and guide the fuel before it is ejected from the injector. Typically, the housing comprises a plurality of parts or components fixedly connected to each other. At least those parts of the housing that are in contact with the fuel may be made of stainless steel. The housing has a nozzle for injecting the fuel, which is arranged at the distal end. The terms "distal end" and "proximal end" refer to the general flow direction of the fuel in the injector toward the distal end. Generally, the distal end is the end of the injector that is close to the nozzle, and the proximal end is the end that is away from the nozzle. The injector extends from the proximal end to the distal end along the injector axis. At least some of the components of the injector may be symmetrical with respect to the injector axis, but generally, the injector axis only defines a reference system, thereby implicitly defining the axial direction, the radial direction and the tangential direction.
[0009] The injector also includes a pivot having an axially extending pivot rod and being axially movable between an open position and a closed position, in which the nozzle is closed from the inside. Typically, the pivot is made of stainless steel. The pivot rod is typically cylindrical and elongated, wherein the length of the pivot rod corresponds to, for example, more than 10 times its diameter. In some embodiments, a ball is fixed to the distal end of the pivot. The ball can also be considered as a part of the pivot. In the closed position, the pivot (or the ball, respectively) closes the nozzle from the inside and prevents fuel injection. In a typical embodiment, the ball engages with the nozzle seat at the distal end of the housing (from the inside of the housing) to close the nozzle. By moving the pivot axially in the proximal direction, it can be moved to an open position in which the nozzle is opened, so that fuel can be injected.
[0010] The fuel injector further comprises an armature, which is arranged in a chamber of the housing so as to be axially movable between a proximal position and a distal position and has an axial through hole in which the pivot rod is received. In other words, the armature is arranged in the chamber so that it can move between the proximal position and the distal position along the injector axis. Here and below, "along the injector axis" particularly but not limited to means "parallel to the injector axis". More generally, it means "at least partially along the direction of the injector axis". The movement principle of the armature is not limited to the scope of the present invention, but usually the armature is moved to the proximal position by a magnetic field and to the distal position by a spring force, wherein at least one movement can be assisted by fuel pressure and / or gravity. Usually, the armature is made of stainless steel. The armature has an axial through hole in which the pivot rod is received. The shape of the through hole is usually suitable for providing a guiding function between the armature and the pivot rod. On the radial outside of the through hole, the armature usually includes at least one fuel channel, usually a plurality of fuel channels, passing through the armature.
[0011] Preferably, the pivot has a radially projecting pivot seat. Typically, the pivot rod and the pivot seat are formed from a single piece. At least, the pivot seat is axially fixed to the pivot rod. In addition, the armature is adapted to engage the pivot seat to transmit an axial force. Typically, when the armature is moved to the proximal position, this force will cause the pivot to move to the open position, but when the armature is moved into the distal position, it will also move the pivot into the closed position. When the armature is engaged with the pivot seat, the proximal movement (or distal movement) of the armature is transmitted to the pivot.
[0012] In addition, the fuel injector comprises an electromagnetic coil. The magnetic coil or solenoid is configured to generate a magnetic field so that the armature moves to the proximal position. The magnetic coil can be arranged circumferentially around the injector axis, for example. It is usually arranged radially outside the housing wall of the housing, while the armature is arranged radially inside. When current flows through the magnetic coil, a magnetic field is generated. Although the windings of the electromagnetic coil are individually isolated to avoid any short circuits, the electromagnetic coil as a whole is usually encapsulated in a non-conductive housing, for example made of plastic.
[0013] The fuel injector further comprises a pole piece arranged in the housing proximal to the armature. Typically, the pole piece is arranged in the chamber, where it is offset in the axial direction relative to the armature. It is arranged proximal to the armature, i.e., the proximal side of the armature. Typically, the pole piece is at least partially radially arranged inside the above-mentioned housing wall, for example, in the same chamber as the armature. The pole piece may also be arranged circumferentially around the injector axis and may have an annular shape. The axial position of the pole piece may correspond more or less to the axial position of the magnetic coil. The function of the pole piece is to be magnetized when the magnetic coil generates a magnetic field and to attract the armature arranged distally. In the case where a pole piece is missing, the magnetic field is shaped and / or enhanced.
[0014] A first spring may be arranged between the housing (or the pole piece) and the pivot seat to bias the pivot distally. In this case, "biasing distally" means applying a biasing force in a distal direction. The function of the first spring may be to keep the pivot seat in contact with the armature and to bring the distal end of the pivot into contact with the nozzle seat. In other words, the armature must counteract and overcome the force of the first spring in order to move the pivot away from the nozzle seat. In addition, a second spring may be arranged between the pole piece and the armature to bias the armature distally. The first spring and the second spring are typically coil springs centered on the injector axis.
[0015] At least one axially movable element of the fuel injector comprises a first contact surface for engaging an axially opposite second contact surface of another element. In particular, the axially movable element may be the armature and / or the pivot, and the other element may be the pole piece, the housing, etc. The other element may be stationary, but may also be the other axially movable element itself. Although the external movable element comprises the first contact surface, the second contact surface is part of a different element that the axially movable element engages during its movement cycle. Typically, both contact surfaces (corresponding elements) are made of stainless steel, but at least one may be made of a different material (e.g., plastic). The first contact surface and the second contact surface are axially opposite to each other, i.e., they are opposite to each other along the axial direction.
[0016] One of the contact surfaces is a separated contact surface radially defined by an inner diameter and an outer diameter, and protrudes toward the other contact surface, wherein at least two contact portions of the separated contact surface are separated by an interposed recessed portion recessed relative to the contact surface, and the other contact surface is shaped to engage with the separated contact surface while being spaced apart from each recess. The separated contact surface can be a first contact surface or a second contact surface, that is, it can be arranged on the axially movable element or other elements. It is defined by an inner diameter and an outer diameter, that is, the entire separated contact surface is arranged between the inner diameter and the outer diameter. The inner diameter corresponds to the innermost radial position of the separated contact surface, and the outer diameter corresponds to the outermost radial position of the separated contact surface. For adjacent surfaces of each element, the separated contact surface protrudes toward the opposite contact surface. In particular, the separated contact surface can be arranged on at least one ridge portion of the corresponding element.
[0017] At least two contact portions of the separated contact surface are separated by an interposed recess that is recessed relative to the separated contact surface. The contact portion is a portion or part of the separated contact surface. They can be connected (for example, via another contact portion), or can be completely separated from each other. In any case, the recess is interposed between the two contact portions so that they are at least partially separated by the recess. It can also be said that the recess (at least partially) separates the contact surface by separating the contact portions, and is therefore referred to as a "separated contact surface". However, it should be noted that in some embodiments, the separated contact surface can be coherent, for example, wherein one or more recesses are arranged inside the contact surface. However, even in this case, the separated contact surface is interrupted by the recess.
[0018] The other contact surface is shaped to engage with the separated contact surface while being spaced apart from each recess. In other words, the shape of the (axially opposite) other surface is adapted so that it does not engage or contact with any recess while engaging with the separated contact surface.
[0019] During the movement cycle of the axially movable element, the first contact surface and the second contact surface repeatedly engage and disengage. Since the space between the elements is filled with fuel during the operation of the fuel injector, this fuel must be displaced to allow the contact surfaces to engage, while on the other hand, the disengagement of the contact surfaces is hindered by the hydraulic contact force, which may cause adhesion. This adhesion effect can be greatly reduced by separating or interrupting the area of the separated contact surface. Although the effects and advantages of the present invention are not limited by this explanation, it may be beneficial that the fuel can be retained in the recess even when the adjacent contact portion is in direct contact with the axially opposite contact surface, or the fuel can flow through the recess so that it can reach certain parts of the contact portion more quickly. On the other hand, compared with the uninterrupted linear contact portion known in the art, the separated contact surface described in the present invention can span a considerable area between the inner diameter and the outer diameter. This helps to evenly distribute the impact force when the first and second contact surfaces engage, thereby reducing stress and extending the life of the fuel injector.
[0020] According to one option, the fuel injector is a gasoline injector, and at least one separated contact surface comprises two radially spaced contact portions separated by radially interposed recesses. According to another option, the fuel injector is a diesel injector, and at least one separated contact surface comprises two tangentially spaced contact portions separated by tangentially interposed recesses. It should be understood that a gasoline injector is suitable for injecting gasoline directly or indirectly into a gasoline engine, while a diesel injector is suitable for injecting diesel directly or indirectly into a diesel engine. The inventors have found that different types of separated contact surfaces are beneficial to diesel injectors and gasoline injectors. Without limiting the invention to this interpretation, different densities and / or different viscosities of gasoline (including ethanol / gasoline mixtures, such as E5 or E10) on the one hand and diesel on the other hand may affect the flow properties, so that, depending on the fuel type, the use of surfaces of different designs can better suppress the adhesion effect. In the case of a gasoline injector, at least one separated contact surface comprises two radially spaced contact portions separated by radially interposed recesses. The recess is between the contact portions along the radial direction. Preferably, the contact portions are completely separated by the recesses. In the case of a diesel injector, at least one separated contact surface comprises two tangentially spaced apart contact portions separated by a tangentially interposed recess. The recess is tangentially interposed between the contact portions. Preferably, the contact portions are completely separated by the recess.
[0021] One embodiment provides that the armature has a first armature contact surface for engaging an axially opposite pivot contact surface of the pivot, and one of the first armature contact surface and the pivot contact surface is a separate contact surface. As described above, the armature, which is moved directly by the magnetic field, engages with the pivot to move it, typically from the closed position to the open position. Thus, the first armature contact surface is typically arranged on the proximal side of the armature, while the pivot contact surface can be arranged on the distal side of the above-mentioned pivot seat.
[0022] In order to limit the proximal movement of the armature relative to the housing, the armature may include a second armature contact surface for engaging the pole piece contact surface of the pole piece when the armature is in the proximal position. One embodiment provides that one of the second armature contact surface and the pole piece contact surface is a separate contact surface. As described above, the pole piece is arranged proximally relative to the armature and when the armature moves to its proximal position, it engages the pole piece contact surface with the second armature surface.
[0023] According to one embodiment, the armature has a third armature contact surface for engaging an axially opposite contact surface, wherein the third armature contact surface is arranged distally on the armature and one of the third armature contact surface and the axially opposite contact surface is a separated contact surface. In this embodiment, the armature is the axially movable element. The third armature contact surface is arranged distally on the armature, i.e. on its distal side. It therefore faces away from the pole piece. In this embodiment, preferably, the third armature surface is a separated contact surface. Preferably, the third armature surface is suitable for at least indirectly engaging the housing. It can be directly engaged with the housing or can be indirectly engaged via an interposed stop ring. This embodiment is particularly helpful to reduce the sticking effect when the armature moves from the distal position to the proximal position.
[0024] According to one embodiment, the third armature contact surface is adapted to engage with an axially opposite housing contact surface of the housing, and one of the third armature contact surface and the housing contact surface is a separate contact surface. The axially opposite housing contact surface is a surface of the housing which may be at a transition from a wider cavity in which the armature is arranged to a narrower cavity in which the pivot shaft is received.
[0025] According to one embodiment, the fuel injector includes a stop ring circumferentially interposed between the armature and the housing, and the third armature contact surface is adapted to engage an axially opposite stop ring contact surface of the stop ring, wherein one of the third armature contact surface and the stop ring contact surface is a separated contact surface. The use of a stop ring is known in the art. It is interposed between the armature and the housing so that the armature does not engage directly with the housing, but engages with the stop ring, which in turn transmits axial forces between the armature and the housing. Typically, the stop ring is made of a non-magnetic material (e.g., plastic or metal). Although it is not fixed to the housing, it does not typically move axially relative to the housing. However, the armature will alternately engage and disengage with the stop ring. As described above, the third armature contact surface is typically arranged at the distal end.
[0026] It should be understood that the terms "first armature contact surface", "second armature contact surface" and "third armature contact surface" are used only to distinguish these contact surfaces, and any one of these contact surfaces can exist without one or both of the other two. In addition, these terms are interchangeable, that is, the first armature contact surface, the second armature contact surface and the third armature contact surface can be referred to as the second armature contact surface, the third armature contact surface and the first armature contact surface, etc.
[0027] In case of several separating surfaces, the housing contact surface, the stop ring contact surface, the pivot contact surface and / or the pole piece contact surface may be separating surfaces. However, it may be beneficial if all separating contact surfaces are located on the armature, so that the other elements may correspond to the prior art and the armature is the only element that needs to be modified.
[0028] Preferably, the two radially spaced apart contact portions are annular. These annular contact portions can be described as two concentric rings separated by a (also concentric) recess. The outer dimensions of the outer contact portion can correspond to the outer diameter of the separated contact surface, while the inner dimensions of the inner contact portion correspond to the inner diameter.
[0029] At least one separated contact surface may comprise a plurality of tangentially (circumferentially) spaced contact portions and a plurality of tangentially interposed recesses arranged alternately along the tangential direction. In other words, a recess is arranged between every two contact portions and vice versa. The number of contact portions (or recesses, respectively) is not limited, but may in particular be between 2 and 50 or between 3 and 20. The tangential dimension of the recess may be much smaller than the tangential dimension of the contact portion, for example as low as 5% of the dimension, but may also be comparable to the tangential dimension of the contact portion, for example corresponding to 80% to 120% of the tangential dimension or even greater. It should be understood that the tangential dimension of the recess may also be between 5% and 80% of the tangential dimension of the contact portion.
[0030] One embodiment provides that at least one contact portion and / or at least one recess is aligned parallel to the radial direction. The corresponding portion is parallel to the radial direction (for example if it has a smaller tangential dimension) or its edge is parallel to the radial direction. It may correspond to an arc portion centered on the injector axis.
[0031] Another embodiment provides that at least one contact portion and / or at least one recess is aligned obliquely with respect to the radial direction and the tangential direction. The same applies to the portion itself or its edges. The overall shape of the cross section can correspond to a portion of a spiral originating from the injector axis. By adjusting the alignment of the recess, the fuel flow through the portion can be influenced, for example accelerated or decelerated.
[0032] Preferably, at least one recess corresponds to between 25% and 75% of the area between the inner diameter and the outer diameter. More specifically, it may correspond to between 40% and 60% of this area. Thus, a considerable part or even a large part of this area does not belong to the contact surface, which reduces the above-mentioned adhesion effect. "The at least one recess" refers to all recesses that separate the contact parts of the separated contact surface, i.e. there may be only one recessed part.
[0033] As described above, the shape of the contact surface opposite to the separated contact surface does not correspond to the recesses, so that it does not contact any of the recesses. Although the separated contact surface with its contact portion and the recess can correspond to an uneven surface with ridges or the like, the relative contact surfaces can be more or less uniform. Preferably, the axially opposite contact surfaces have a minimum radius of curvature corresponding to at least 50% of the inner diameter. This also includes the possibility that the contact surface is flat, so that the (minimum) radius of curvature is infinite. Inclined surfaces, i.e. surfaces having at least one edge, are considered to have a (almost) zero radius of curvature. Therefore, in this embodiment, the relative contact surfaces have no angles and either no curvature or only a relatively moderate curvature. In particular, the relative contact surfaces may be flat.
[0034] In the process of producing an element with the separated contact surface, a structure with the contact portion and the recess can be created in various ways (such as). In particular, at least one recess can be produced by a forming process and / or a material removal process performed in the area between the inner diameter and the outer diameter. "Forming" refers to any process that changes the shape of the material without removing or adding material. This can be hot forming, or it can also be cold forming. The latter is also possible because of the fact that the recessed portion is usually less than 1mm recessed relative to the contact portion. Possible forming processes include, but are not limited to, rolling, stamping and knurling. Suitable material removal processes include, but are not limited to, machining, turning, milling, etching and laser ablation. In particular, at least one separated contact surface can include a plurality of alternating, radially aligned contact portions and recesses formed by knurling. For example, the number of contact portions can be between 10 and 100 or between 20 and 50.
[0035] The invention also relates to an engine system having a combustion engine and at least one fuel injector adapted to at least indirectly inject fuel into the engine, the fuel injector comprising:
[0036] a housing extending axially along the injector axis from a proximal end to a distal end and having a nozzle at the distal end,
[0037] a pivot having an axially extending pivot rod, the pivot being axially movable between an open position and a closed position in which the pivot closes the nozzle from the inside,
[0038] an armature arranged in the chamber of the housing so as to be axially movable between a proximal position and a distal position and having an axial through hole in which the pivot rod is received,
[0039] - a magnetic coil, and
[0040] - a pole piece arranged in the housing on the proximal side of the armature,
[0041] wherein at least one axially movable element of the fuel injector comprises a first contact surface for engaging with an axially opposite second contact surface of another element, one of the contact surfaces is a separated contact surface, the separated contact surface is radially defined by an inner diameter and an outer diameter and protrudes toward the other contact surface, wherein at least two contact portions of the separated contact surface are separated by an inserted recess recessed relative to the separated contact surface, and the other contact surface is formed to engage with the separated contact surface while being spaced apart from each recess, wherein the engine is a gasoline engine, the fuel injector is a gasoline injector, and at least one separated contact surface comprises two radially spaced contact portions separated by radially inserted recesses, or the engine is a diesel engine, the fuel injector is a diesel injector, and at least one separated contact surface comprises two tangentially spaced contact portions separated by tangentially inserted recesses.
[0042] The injector may be suitable for injecting fuel directly into the engine, in particular into the combustion chamber of the engine. Alternatively, it may be suitable for indirect injection, i.e. injecting the fuel into the intake duct of the engine. Although the engine and the injector are regarded as components of the engine system, the injector (and possibly the intake duct) may also be regarded as part of the engine. All other terms have already been discussed with respect to the fuel injector of the present invention and will not be explained again. Preferred embodiments of the engine system of the present invention correspond to embodiments of the injector of the present invention.
[0043] A combustion engine is typically an internal combustion engine having a plurality of cylinders, which is configured for a single stroke cycle. The injector is part of a fuel delivery system which includes a fuel tank containing the relevant fuel (diesel or gasoline), at least one fuel pump that delivers the fuel from the fuel tank to a fuel rail to which the injector is connected. The gasoline engine includes a spark plug. The fuel delivery system of the diesel engine is designed to operate at relatively high pressures and uses compression ignition. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Preferred embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:
[0045] Figure 1 is a longitudinal sectional view of a fuel injector of the present invention;
[0046] Figure 2 yes Figure 1Detailed view of
[0047] Figure 3 yes Figure 1 A perspective view of a first embodiment of an armature of a fuel injector;
[0048] Figure 4 is a perspective view of a second embodiment of the armature;
[0049] Figure 5 is a perspective view of a third embodiment of the armature;
[0050] Figure 6 yes Figure 1 A perspective view of a first embodiment of a pole piece for a fuel injector; and
[0051] Figure 7 yes Figure 1 A perspective view of a second embodiment of a pole piece of a fuel injector;
[0052] Figure 8 yes Figure 4 Detailed cross-sectional view of
[0053] Fig. 9 yes Figure 3 A detailed cross-sectional view of an alternative design of the second armature contact surface of the armature. DETAILED DESCRIPTION
[0054] Figure 1 and Figure 2 The fuel injector 1 of the present invention is schematically shown, and the fuel injector can be used in a combustion engine (e.g., a diesel engine or a gasoline engine). It can be used in an engine system of the present invention including a combustion engine and the fuel injector 1. Although some features may differ depending on whether the fuel injector 1 is a gasoline injector or a diesel injector, Figure 1 and Figure 2 It should be understood that both types of injectors are represented. The fuel injector 1 comprises a housing 2 consisting of several stainless steel parts, which will not be explained in detail here. The housing 2 extends along the injector axis A from a proximal end 2.1 to a distal end 2.2, where a nozzle 4 is arranged. A chamber 8 is formed inside the housing 2, which extends to the nozzle 4 and is suitable for guiding fuel through the fuel injector 1.
[0055] The nozzle 4 may be closed by a stainless steel pivot 10 arranged in the housing 2. The pivot 10 has an axially extending elongated pivot rod 10.1 from which an annular collar, referred to as a pivot seat 10.2, radially projects. Figure 1 and Figure 2As shown in , the pivot 10 is axially movable between an open position (not shown) and a closed position. In the closed position, the ball 11 at the distal end of the pivot 10 rests on the nozzle seat 4.1 of the nozzle 4, thereby closing the nozzle 4. If the pivot 10 is moved proximally toward the open position, the ball 11 is lifted off the nozzle seat 4.1, thereby opening the nozzle 4. The first spring 6 is arranged between the pivot seat 10.2 and the pole piece 3 connected to the housing 2. The first spring 6 is a coil spring, which is aligned along the injector axis A and applies a force to bias the pivot 10 distally, i.e., in the distal direction.
[0056] The fuel injector 1 further comprises an armature 12 having a generally annular shape and surrounding the pivot 10. The armature 12 has an axial through hole 12.1 in which the pivot rod 10.1 is received. The armature 12, which is also made of stainless steel, can move axially along the pivot rod 10.1, but radial movement relative to the pivot 10 is greatly limited. With respect to the radially outer side of the through hole 12.1, the armature 12 comprises a plurality of fuel passages 12.2 (see Figures 3 to 5 ), these fuel passages are connected to the chamber 8 to allow fuel to pass through the armature 12. The armature 12 is axially movable in the housing 2 between a proximal position and a distal position. Figure 1 3. In the distal position shown in the figure, the first armature contact surface 12.3 is in contact with the pivot contact surface 10.3 of the pivot, while the second armature contact surface 12.4 on the proximal side of the armature 12 is axially separated from the opposite pole piece contact surface 3.1 of the pole piece 3. The third armature contact surface 12.5 is seated against the axially opposite stop ring contact surface 14.1 of the stop ring 14, which is interposed between the armature 12 and the stop portion 2.4 of the housing 2. The stop ring 14 is made of non-magnetic material (e.g. plastic). In the proximal position not shown in the figure, the second armature stop surface 12.4 is engaged with the pole piece stop surface 3.1.
[0057] The chamber 8 is defined by a housing wall 2.3 arranged adjacent to the armature 12 and the pole piece 3. The electromagnetic coil 5 is arranged radially outside the housing wall 2.3. It is encapsulated in a plastic housing 13 to provide electrical insulation. If a current flows through the magnetic coil 5, a magnetic field is generated, which also enters the pole piece 3 and the armature 12, whereby the armature 12 is pulled toward the pole piece 3 and into the proximal position. The second spring 7 is arranged between the housing 2 or more specifically the pole piece 3 and the armature 12 to bias the armature 12 distally. As long as no magnetic field acts on the armature 12, it is held in the distal position by the second spring 7.
[0058] The magnetic flux can also reach the stop portion 2.4 opposite the third armature contact surface 12.5. This may cause a magnetic force to act on the armature 12 in the distal direction, thereby delaying the lifting of the armature 12. In order to avoid this, a non-magnetizable stop ring 14 is inserted to keep the armature 12 at a certain distance from the stop portion 2.4.
[0059] When the armature 12 moves to the proximal position, it engages with the pivot seat 10.2, thereby transmitting an axial force to move the pivot 10 to the open position. More specifically, the first armature contact surface 12.3 engages with the pivot contact surface 10.3 to transmit the force.
[0060] When the armature 12 and the pivot shaft 10 are axially moved between their respective end positions, the armature contact surfaces 12.3 to 12.5 alternately engage and disengage with the axially opposite contact surfaces 3.1, 10.3, 14.1. Since the space between the elements is filled with fuel, this fuel must be displaced to allow the contact surfaces 3.1, 10.3, 12.3-12.5, 14.1 to engage, while on the other hand, the disengagement of the contact surfaces 3.1, 10.3, 12.3-12.5, 14.1 is hindered by hydraulic contact forces that may cause sticking. In order to reduce this sticking effect, one of each pair of axially opposite contact surfaces 3.1, 10.3, 12.3-12.5, 14.1 is a separated contact surface.
[0061] Figure 3 A first embodiment of an armature 12 is shown, wherein each of the first armature contact surface 12.3, the second armature contact surface 12.4 and the third armature contact surface 12.5 is a separate contact surface. The armature 12 is suitable for use in a diesel injector. Figure 3 As shown in , the first armature contact surface 12.3 is arranged in an annular area between the first inner diameter r1 and the first outer diameter r2. However, it is not a single continuous area, but includes a plurality of contact portions 15 (here: twelve contact portions 15), which are tangentially (circumferentially) separated by interposed recesses 16, which are aligned parallel to the radial direction. While the contact portion 15 protrudes toward the axially opposite pivot contact surface 10.3, the recess 16 is recessed relative to the contact portion 15. Therefore, the recess 16 can also be called a slotted portion. Therefore, since the pivot contact surface 10.3 is flat, only the contact portion 15 engages with the pivot contact surface 10.3, while the recess 16 remains out of contact. It has been found that the adhesion effect can be greatly reduced by separating or interrupting the area of the separated contact surface (in this case, the first armature contact surface 12.3). On the other hand, since the first armature contact surface 12.3 spans the first inner diameter r 1 and the first outer diameter r 2The recess 16 corresponds to a first inner diameter r , so that any impact forces that occur are well distributed, thereby reducing stress and extending the life of the fuel injector 1. In the embodiment shown, the recess 16 corresponds to the first inner diameter r 1 With the first outer diameter r 2 25% of the area between, but this percentage can be lower or higher, such as up to 75% or higher. Generally, in various embodiments, the contact portion 15 can generally have a flat surface (i.e., the surface that engages with the contact surface of the opposing element, here the pivot contact surface 13).
[0062] like Figure 3 As shown in FIG. 1 , the second armature contact surface 12.4 is arranged at the second inner diameter r 3 and the second outer diameter r 4 It comprises a plurality of contact portions 15 (here 30 contact portions 15) which are tangentially separated by interposed recesses 16. The axially opposite pole piece contact surfaces 3.1 are substantially flat. In the embodiment shown, the recesses 16 correspond to the second inner diameter r 3 and the second outer diameter r 4 , but this percentage may be lower or higher, for example between 25% and 75% or higher. The third armature contact surface 12.5 is not shown in this embodiment, but has a similar configuration to the first armature contact surface 12.3 and the second armature contact surface 12.4. In that it also comprises a plurality of contact portions 15 tangentially separated by interposed recesses 16 aligned parallel to the radial direction.
[0063] Figure 4 A second embodiment of an armature suitable for use in a gasoline injector is shown. Figure 4 As shown in FIG. 1 , the third armature contact surface 12.5 is arranged between the third inner diameter r 5 and the third outer diameter r 6 It comprises two concentrically arranged annular contact portions 15 which are radially separated by an interposed annular recess 16. The axially opposite stop ring contact surfaces 14.1 are substantially flat. Here, the recess 16 corresponds to the second inner diameter r 3 and the second outer diameter r 4 40% of the area between 30° and 100°, but the percentage may be lower or higher, for example between 25% and 75%.
[0064] Figure 8 yes Figure 41 and illustrates in cross section the lower part of the armature 12 with the third armature contact surface 12.5. This view shows more clearly the two annular contact portions 15 which are arranged concentrically and radially spaced apart by the interposed annular recess 16. The two annular contact portions 15 thus form two raised (and flat) surfaces separated by the annular groove constituting the annular recess 16.
[0065] Fig. 9 The cross section shows Figure 4 The design of the second armature contact surface (marked 12.4') of the armature shown in FIG. Figure 4 The second armature contact surface 12.4' comprises two annular contact portions 15 which are arranged concentrically and radially spaced apart by an interposed annular recess 16. The first armature contact surface 12.3 (not shown) of the armature 12 may be configured in a similar manner.
[0066] Figure 5 A third embodiment of the armature 12 is shown with a second armature contact surface 12.4 of still a different type. It comprises a large number (more than 100) of contact portions 15 which are tangentially separated by interposed recesses 16. Here, the recesses correspond to the second inner diameter r 3 and the second outer diameter r 4 50% of the area between. Such a surface profile for the separated contact surface can be produced, for example, by knurling. As with the first embodiment, the armature is suitable for use in a diesel injector.
[0067] As an alternative to separate contact surfaces being arranged on the armature 12 , they can be arranged on the pole piece 3 , the pivot 10 , the stop ring 14 or the housing 2 , respectively. Figure 6 and Figure 7 Examples are shown in which the pole piece contact surface 3.1 is a separated contact surface. In these embodiments, the axially opposite second armature contact surface 12.4 is flat. The pole piece contact surface 3.1 is arranged at the fourth inner diameter r 7 With the fourth outer diameter r 8 It comprises a plurality of contact portions 15 which are tangentially separated by insertion recesses 16 aligned in the radial direction. Here, the recesses 16 correspond to the fourth inner diameter r 7 With the fourth outer diameter r 8 The pole piece can be used exclusively in diesel injectors.
[0068] Figure 7The embodiment of is similar. However, in this case, the recesses 16 are aligned obliquely with respect to the radial and tangential directions, ie they correspond to parts of the spiral. Furthermore, the recesses 16 are smaller, which corresponds to the fourth inner diameter r 7 With the fourth outer diameter r 8 The pole piece can be used in both diesel injectors and gasoline injectors.
[0069] exist Figure 1 and Figure 2 In the fuel injector 1 shown in FIG. 1 , the armature 12 and the housing 2 are axially separated by a stop ring 14. In an alternative not shown in the figures, the stop ring 14 can be omitted, wherein the third armature contact surface 12.5 directly engages with the housing contact surface 2.5, which can then optionally be a separated contact surface.
[0070] List of reference numerals:
[0071] 1 Fuel Injector
[0072] 2 Housing
[0073] 2.1 Near End
[0074] 2.2 Remote
[0075] 2.3 Shell wall
[0076] 2.4 Stopper
[0077] 2.5 Shell contact surface
[0078] 3 pole piece
[0079] 3.1 Pole contact surface
[0080] 4 Nozzles
[0081] 4.1 Nozzle holder
[0082] 5 Magnetic coil
[0083] 6.7 Spring
[0084] 8 Chamber
[0085] 10 Pivot
[0086] 10.1 Pivot rod
[0087] 10.2 Pivot seat
[0088] 10.3 Pivot contact surface
[0089] 11 Ball
[0090] 12 Armature
[0091] 12.1 Through Holes
[0092] 12.2 Fuel Channel
[0093] 12.3 to 12.5 armature contact surface
[0094] 13 Plastic housing
[0095] 14 Snap ring
[0096] 14.1 Snap ring contact surface
[0097] 15 Contact part
[0098] 16 recess
[0099] A Injector axis
[0100] r 1 、r 3 、r 5 、r 7 inner diameter
[0101] r 2 、r 4 、r 6 、r 8 outer diameter
Claims
1. A fuel injector (1), comprising: a housing (2) extending axially along the injector axis (A) from a proximal end (2.1) to a distal end (2.2) and having a nozzle (4) at the distal end (2.2), a pivot (10) having an axially extending pivot rod (10.1), the pivot (10) being axially movable between an open position and a closed position, in which the pivot closes the nozzle (4) from the inside, an armature (12) arranged in the chamber (8) of the housing (2) so as to be axially movable between a proximal position and a distal position and having an axial through hole (12.1) for receiving the pivot rod (10.1), a magnetic coil (5), and a pole piece (3), the pole piece being arranged in the housing (2) and being located near the armature (12), wherein at least one axially movable element (10, 12) of the fuel injector (1) comprises a first contact surface (10.3, 12.3-12.5) for engaging with an axially opposite second contact surface (2.5, 3.1, 10.3, 12.3, 14.1) of another element (2, 3, 10, 12, 14), one of the contact surfaces (2.5, 3.1, 10.3, 12.3-12.5, 14.1) being a separated contact surface (3.1, 12.3-12.5) radially delimited by an inner diameter (r1, r3, r5, r7) and an outer diameter (r2, r4, r6, r8) and protruding towards the other contact surface (2.5, 3.1, 10.3, 12.3-12.5, 14.1), wherein the separated contact surface (3.1 , 12.3-12.5) are separated by an inserted recess (16) recessed relative to the separated contact surface (3.1, 12.3-12.5), and another contact surface is formed to engage with the separated contact surface (3.1, 12.3-12.5) while being spaced from each recess (16), wherein the fuel injector (1) is a gasoline injector and at least one of the separated contact surfaces (3.1, 12.3-12.5) includes two radially spaced contact portions (15) separated by the radially inserted recess (16), or the fuel injector (1) is a diesel injector and at least one of the separated contact surfaces (3.1, 12.3-12.5) includes two tangentially spaced contact portions (15) separated by the tangentially inserted recess (16).
2. The fuel injector according to claim 1, wherein: The armature (12) has a first armature contact surface (12.3) for engaging an axially opposite pivot contact surface (10.3) of the pivot shaft (10), and one of the first armature contact surface (12.3) and the pivot contact surface (10.3) is a separate contact surface.
3. A fuel injector according to any one of the preceding claims, wherein: The armature (12) has a second armature contact surface (12.4) for engaging a pole piece contact surface (3.1) of the pole piece (3), and one of the second armature contact surface (12.4) and the pole piece contact surface (3.1) is a separate contact surface.
4. A fuel injector according to any one of the preceding claims, wherein: The armature (12) has a third armature contact surface (12.5) for engaging an axially opposite contact surface (2.5, 14.1), wherein the third armature contact surface (12.5) is arranged at a distal side of the armature (12), and one of the third armature contact surface (12.5) and the axially opposite contact surface (2.5, 14.1) is a separate contact surface.
5. A fuel injector according to any one of the preceding claims, wherein: The third armature contact surface (12.5) is adapted to engage an axially opposite housing contact surface (2.5) of the housing (2), and one of the third armature contact surface (12.5) and the housing contact surface (2.5) is a separate contact surface.
6. A fuel injector according to any one of the preceding claims, comprising a stop ring (14) axially interposed between the armature (12) and the housing (2), and wherein the third armature contact surface (12.5) is adapted to engage an axially opposite stop ring contact surface (14.1) of the stop ring (14), wherein One of the third armature contact surface (12.5) and the stop ring contact surface (14.1) is a separate contact surface.
7. A fuel injector according to any one of the preceding claims, wherein: The radially spaced contact portions (15) are annular.
8. A fuel injector according to any one of the preceding claims, wherein: At least one separated contact surface (3.1, 12.3-12.5) comprises a plurality of tangentially spaced apart contact portions (15) and a plurality of tangentially interposed recesses (16) arranged alternately along a tangential direction.
9. A fuel injector according to any one of the preceding claims, wherein: At least one contact portion (15) and / or at least one recess (16) is aligned parallel to the radial direction.
10. The fuel injector according to claim 9, wherein: At least one spaced apart contact surface (12.4) comprises a plurality of alternating, radially aligned contact portions (15) and recesses (16) formed by knurling.
11. A fuel injector according to any one of the preceding claims, wherein: The at least one recess (16) corresponds to between 25% and 75% of the area between the inner diameter (r1, r3, r5, r7) and the outer diameter (r2, r4, r6, r8).
12. A fuel injector according to any one of the preceding claims, wherein: The axially opposed contact surfaces have a minimum radius of curvature corresponding to at least 50% of the inner diameter (r1, r3, r5, r7).
13. A fuel injector according to any one of the preceding claims, wherein: The at least one recess (16) is produced by a forming process and / or a material removal process performed in the region between the inner diameter (r1, r3, r5, r7) and the outer diameter (r2, r4, r6, r8).
14. An engine system having a combustion engine and at least one fuel injector (1), the fuel injector being adapted to at least indirectly inject fuel into the engine, the fuel injector (1) comprising: a housing (2) extending axially along the injector axis (A) from a proximal end (2.1) to a distal end (2.2) and having a nozzle (4) at the distal end (2.2), a pivot (10) having an axially extending pivot rod (10.1), the pivot (10) being axially movable between an open position and a closed position, in which the pivot closes the nozzle (4) from the inside, an armature (12) arranged in the chamber (8) of the housing (2) so as to be axially movable between a proximal position and a distal position and having an axial through hole (12.1) for receiving the pivot rod (10.1), a magnetic coil (5), and a pole piece (3), the pole piece being arranged in the housing (2) and being located near the armature (12), wherein at least one axially movable element (10, 12) of the fuel injector (1) comprises a first contact surface (10.3, 12.3-12.5) for engaging with an axially opposite second contact surface (2.5, 3.1, 10.3, 12.3-12.5, 14.1) of another element (2, 3, 10, 12, 14), wherein the contact surface (2.5, 3.1, 10.3, 12.3-12.5) is arranged to be movable in a direction opposite to the first contact surface (10.3, 12.3-12.5) of the fuel injector (1) .5, 14.1) is a separated contact surface (3.1, 12.3-12.5), which is radially bounded by an inner diameter (r1, r3, r5, r7) and an outer diameter (r2, r4, r6, r8) and protrudes toward the other contact surface (2.5, 3.1, 10.3, 12.3-12.5, 14.1), wherein the separated contact surface (3.1, 12.3-12.5) is radially bounded by an inner diameter (r1, r3, r5, r7) and an outer diameter (r2, r4, r6, r8) and protrudes toward the other contact surface (2.5, 3.1, 10.3, 12.3-12.5, 14.1). At least two contact portions (15) of the engine (5) are separated by an interposed recess (16) recessed relative to the separated contact surface (3.1, 12.3-12.5), and another contact surface is formed to engage with the separated contact surface (3.1, 12.3-12.5) while being spaced apart from each recess (16), wherein the engine is a gasoline engine, the fuel injector (1) is a gasoline injector, and at least one of the separated contact surfaces (3.1, 12.3-12.5) includes two radially spaced contact portions (15) separated by the radially interposed recess (16), or the engine is a diesel engine, the fuel injector (1) is a diesel injector, and at least one of the separated contact surfaces (3.1, 12.3-12.5) includes two tangentially spaced contact portions (15) separated by the tangentially interposed recess (16).