JP2018173079A - Valve sleeve of injector and method for manufacturing valve sleeve of injector - Google Patents

Abstract

SOLUTION: The invention relates to a valve sleeve (3) of an injector (1) for injecting a medium (8), in particular a fuel, which comprises at least one cylindrical sleeve (10) and an injector head (11), wherein the injector head (11) has a closing element seat (13) and at least one injection hole (15), and the injector head (11) is processed using an addition manufacturing method and is attached to the cylinder sleeve (10) by material connection.EFFECT: A valve sleeve can be manufactured at low cost by an extremely effective method even if having a complicated geometric shape.SELECTED DRAWING: Figure 1

Description

PRIOR ART The present invention relates to a valve sleeve optimized for production, for an injector for injecting a medium, partially manufactured using an additive manufacturing method, an injector with such a valve sleeve, and its manufacture With respect to methods.

  Injectors for introducing a medium, for example injectors for injecting liquid fuel or for feeding gaseous fuel, are known in various ways from the prior art. An injector of this kind is known, for example, from DE 10 2013 132 20836. The injector typically has a valve sleeve and an injector head that surround the pressure chamber together with other components. A closing element is movably arranged in the valve sleeve along the longitudinal axis and cooperates with the closing element seat during axial movement. Depending on its position, the closure element opens or closes one or more injection holes drilled in the injector head, so that the fuel is pushed out of the pressure chamber under high pressure, so that the fuel can be removed from the injection hole. Sprayed.

  Based on the ever increasing demand for injectors that take into account spray formation, the supply of fuel from the pressure chamber to the injection holes takes place through a complex geometry in the valve sleeve. This valve sleeve allows for the best spray spread when setting the maximum spray target and during optimal penetration. The production of this complex geometry in the valve sleeve is based on a number of production methods to be applied, undercuts and extremely small geometric dimensions, which is particularly costly and thus inefficient. .

DISCLOSURE OF THE INVENTION On the other hand, the valve sleeve of an injector according to the invention with the features of claim 1 may be that the valve sleeve has any complex geometry, and at the same time the method of manufacturing the valve sleeve comprises: In particular, it has the advantage of being optimized such that a time advantage results in a cost advantage. In accordance with the present invention, this means that the valve sleeve comprises at least one cylinder sleeve and an injector head, the injector head having a closing element seat and at least one injection hole, the injector head using an additional manufacturing method. This is accomplished by being machined and attached to the cylinder sleeve by a material connection. This allows the valve sleeve to be manufactured in a very effective way at low cost, even with complex geometric shapes. In addition, additive manufacturing methods are very complex geometries in the injector head, such as undercuts, curved holes or the like, which can only be manufactured with great effort (in the first place) by conventional manufacturing methods. Make it feasible.

  The dependent claims show preferred refinements of the invention.

  Preferably, a supply area having at least one flow pocket or at least one flow hole is arranged in the injector head. The flow pocket or flow hole enlarges the effective flow surface through which fuel can flow from the pressure chamber to the closure element seat. The flow pockets or flow holes can be distributed symmetrically or asymmetrically over the circumference around the longitudinal axis. In particular, by arranging at least one flow pocket or flow hole corresponding to at least one injection hole, the flow pocket or flow hole can be arranged asymmetrically in the injector head.

  According to another preferred embodiment, the flow pocket is shaped as a kind of groove in the inner wall of the injector head, for example as a kind of sliding bearing, supporting the closing element in the radial direction and / or At least one web for guiding is formed. In contrast, the flow holes can be formed in an annularly extending web formed as a kind of step on the inner wall of the injector head. A combination of flow pockets and flow holes in the injector head is possible.

  According to still another preferred aspect, the injector head has at least one front portion that communicates with at least one injection hole. Since the flow-through surface of the injection hole is expanded stepwise at least once by the front stage part, the effective length of the injection hole is reduced by the front stage part, and the injection hole itself is protected from carbon adhesion.

  Preferably, the at least one injection hole has a cylindrical or curved flow passage. The shape of the flow passage can affect target setting and spray formation, thereby achieving optimal distribution of media in the space during injection. In that case, the cross section of the flow passage may be circular, elliptical and / or polygonal.

  Further, it has been found that it is particularly advantageous if the injector head is processed and attached to the cylinder sleeve by an electron beam melting method (EBM), which is also called electron beam melting. Electron beam additive manufacturing (EBM) is a method based on a powder bed, in which metal powder is melted in a vacuum using an electron beam. This method proceeds at high process temperatures and may require a support structure depending on the geometry of the injector head. Non-inertial beam deflection (multi-beam strategy) can generate parallel fusions and thus increase the speed with which one or more injector heads can be formed, thereby reducing production time. It can be greatly reduced. As the raw material for the injector head, a spherical powder having a particle diameter of 45 μm to 105 μm is preferably used. The raw material for the injector head must be formed from a conductive, weldable metal raw material, but magnetic raw materials should not be used because beam deflection can occur. In accordance with electron beam additive manufacturing (EBM), residual powder can be removed from the completed valve sleeve in a subsequent method step, possibly removing excess support structure. Further optionally, the completed cylinder sleeve can be heat treated. For final processing, in particular to form a closing element seat that closes the injector in a gas-tight and liquid-tight manner with the closing element, for example grinding, honing, turning or the like The method can be used.

  According to another advantageous aspect, the injector head can be provided on the cylinder sleeve by a selective laser additive manufacturing (SLM). Selective laser additive manufacturing (SLM) is also known as Direct Metal Laser Sintering (DMLS), Laser Beam Melting (LBM), LaserCUSING, or laser sintering. Selective laser additive manufacturing (SLM) is a method based on a powder bed, in which components are constructed in layers. The powder is applied in layers by a squeegee and is subsequently melted locally using a laser. The process is carried out under an inert gas atmosphere and preferably has a process temperature of 200 ° C to 500 ° C. Depending on the geometry of the injector head, a support structure may be necessary for selective laser additive manufacturing (SLM). As a material for the injector head, a weldable metal raw material can be preferably used as a spherical powder having a particle size of 10 μm to 45 μm. Examples of the raw material include nickel base alloys, tool steels, aluminum alloys, titanium alloys, and the like. According to the selective laser additive manufacturing method, the residual powder can first be removed from the valve sleeve, optionally the excess support structure can be removed and the heat treatment can be carried out. Further processing / finishing, in particular functional surface processing / finishing, can be carried out without problems using conventional manufacturing methods. The selective laser additive manufacturing method has an advantage that a magnetic material can be processed without any problems as compared with the electron beam additive manufacturing method. The selective laser additive manufacturing method has a high dimensional accuracy of ± 50 μm and a relatively good surface quality of Rz of about 30 μm to 50 μm.

  Preferably, the cylinder sleeve is a rotationally symmetric turning part made from a weldable metal source. A cylinder sleeve is a component that can be easily and inexpensively manufactured in large numbers. The cylinder sleeve can be cleaned according to the manufacturing process, for example to add an injector head, by means of a suitable cleaning method and clamped to a device suitable for the additional manufacturing method. The cylinder sleeve is then machined with an injector head, in which case the injector head comprises only a small part of the overall valve sleeve. Normally, the mass of the cylinder sleeve is about 70% of the total mass of the valve sleeve. However, a higher mass fraction is advantageous to achieve further cost advantages. The cylinder sleeve may preferably have one or more steps.

  According to another advantageous aspect, an injector, in particular a fuel injector, has a valve sleeve formed from a cylinder sleeve and an injector head, in which case the injector head is additionally machined and attached to the cylinder sleeve. . Therefore, the injector can be used in various and individual ways depending on the valve sleeve to be manufactured at low cost.

  According to yet another advantageous aspect, the valve sleeve can be manufactured in at least two method steps. In the first method step, the cylinder sleeve is prepared as a low-cost turning part, and in the second method step, the injector head is processed and attached to the cylinder sleeve using an additive manufacturing method.

  Furthermore, since the cylinder sleeve is cleaned prior to the additive manufacturing process, it is particularly advantageous if contaminants such as grease, oil, litter or the like are removed.

  In the following, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of an injector for injecting a medium with a valve sleeve according to the invention. FIG. 2 is an enlarged schematic cross-sectional view of the valve sleeve according to the present invention shown in FIG. 1. FIG. 3 is an enlarged schematic partial cross-sectional view of the valve sleeve shown in FIG. 2 taken along section line YY. It is an enlarged view of the valve sleeve for injectors in the state which can be assembled.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an injector and a valve sleeve according to a preferred first embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 shows a longitudinal section of an injector 1 with a valve sleeve 3 according to the invention. In particular, the injector 1 has a pressure chamber 5 surrounded by a valve sleeve 3 and an injector housing 4. In this pressure chamber 5, the closing element 6 is arranged by an actuator 60 so as to be slidable along the longitudinal axis XX. The pressure chamber 5 is connected, for example, to an accumulator by means of a high pressure port (not shown) and is filled with a medium 8 under a very high pressure up to 350 × 10 ⁵ Pa by this accumulator. As the closing element 6 moves along the longitudinal axis XX, the closing element 6 cooperates with a closing element seat 13 formed in the valve sleeve 3 to open and close the injection hole 15. 1 and 2 show the closed state of the injector 1.

  The injector 1 is an internal valve opening type injector 1, and in this case, the opening direction is opposite to the outflow direction A from the injector 1.

  The actuator 60 is a solenoid actuator and includes an armature 61 and a coil 62. Due to the cooperation of the actuator 60 and the armature 61, the closing element 6 is movable along the longitudinal axis XX. The closing element 6 is formed as a valve needle with a valve ball 50 and a stopper 55. A return element 66 is supported on the stopper 55 of the closure element 6 and holds the closure element 6 in the closed position shown in FIGS. The actuator 60 may be formed as a piezo adjuster.

  The function of the injector 1 according to the first embodiment is as follows: when the opening process is introduced, the actuator force by the actuator 60 is applied to the armature 61, so that the armature 61 together with the closing element 6 is longitudinal It is moved in the direction opposite to the outflow direction A along the axis XX. As soon as the injection hole 15 is opened by the closing element 6 during the opening process, the medium 8 under pressure passes from the pressure chamber 5 through the injection hole 15 into the space 2 in the spray state, for example in the combustion chamber of the internal combustion engine. It flows to. The medium 8 may be a liquid or gaseous medium.

  In the resting state of the injector 1 illustrated in FIGS. 1 and 2, the valve ball 50 is pressed against the closing element seat 13 of the injector head 11 by the spring force of the return element 66. Is closed or separated from the remaining pressure chamber 5 in a gas-tight and liquid-tight manner. For this purpose, the shape of the closure element seat 13 is adapted to the shape of the valve ball 50.

  The valve sleeve 3 can be seen in detail from FIG. 2 and is integrally formed from two parts and comprises a cylinder sleeve 10 and an injector head 11. The cylinder sleeve 10 is a rotationally symmetric turning portion made of a weldable metal raw material. The injector head 11 is machined using an additive manufacturing method and is attached to the cylinder sleeve 10, and in the outflow direction A along the longitudinal axis XX, the supply area 12, the closing element seat 13, the inflow area 14, , Having at least one injection hole 15 and a front stage 16. When the injector 1 is in the open position, the medium 8 flows from the pressure chamber 5 through the supply area 12, by the closing element seat 13 into the inflow area 14 and away from the inflow area 14. Then, it goes to the direction of the space 2 through the injection hole 15. The diameter of the front stage portion 16 is set to be considerably larger than the diameter of the injection hole 15, and in this case, the illustrated mode of the injection hole 15 is the injector 1 including the narrow front stage section having a depth. The length L2 of the front stage portion 16 in the outflow direction A is set to be considerably larger than the length L1 of the injection hole 15. Furthermore, the ratio of the diameter of the flow surface of the front stage 16 and the flow surface of the injection hole 15 is about 2: 1.

  FIG. 3 shows a cross-sectional view of the injector 1 shown in FIG. 2 along the plane of the cross-sectional line YY. In the injector head 11, a plurality of flow pockets 20, a plurality of flow holes 21, and a plurality of webs 22 are arranged over the circumference. Since the flow pocket 20 and the flow hole 21 enlarge the effective flow cross section in the direction of the longitudinal axis XX of the injector 1 in the region of the supply area 12, the medium 8 is expanded by the enlargement of the cross section. As soon as possible and with a slight pressure drop, it can flow into the inlet region 14 and thus into the injection hole 15.

  For this purpose, the flow pockets 20 and the flow holes 21 may be formed in the injector head 11 such that one or more webs 22 are formed. The web 22 forms a guide surface for the valve ball 50 or the closing element 6 and supports this guide surface in the radial direction. Accordingly, the flow pocket 20, the flow hole 21 and the web 22 pass from the closing element seat 13 along the longitudinal axis XX, at least when the valve ball 50 passes when the injector 1 is opened and closed. Extends across the entire route.

  The plurality of injection holes 15 are formed in the injector head 11 so as to correspond to the positioning of the flow pockets 20 or the flow holes 21 in the inflow region 14 over the circumference. The circumferential position of the flow hole 21 corresponds to the circumferential position of the injection hole 15. However, the injection hole 15 can be positioned without depending on the flow pocket 20 and the flow hole 21.

  In this aspect, the production of the valve sleeve 3 according to the invention takes place in at least two method steps. First, the cylinder sleeve 10 is manufactured as a symmetrical turning part, and in the second method step, the injector head 11 is joined to the cylinder sleeve 10 using an additive manufacturing method. A region between the injector head 11 and the cylinder sleeve 10 is a transition region 9. In the transition region 9, a very small amount of the material of the cylinder sleeve 10 is melted when the injector head 11 is provided, so that a material connection between the cylinder sleeve 10 and the injector head 11 occurs.

  The cylinder sleeve 10 is manufactured from a weldable metal source and can be cleaned prior to the second method step. During cleaning of the cylinder sleeve 10, possible contaminants such as coolant residues, oil, grease, debris, or the like are removed. Contaminants may be removed only partially. The cylinder sleeve 10 is subsequently clamped to the appropriate device for the additive manufacturing method. To this end, for example, a hydraulic chuck or a multi-chuck formed from two half shells can be used.

  As an additional manufacturing method, a selective laser additive manufacturing method (SLM) or an electron beam additive manufacturing method (EBM) is applied.

  Electron beam additive manufacturing (EBM) is a method based on a powder bed. In this method, metal powder is gradually melted along the cylinder sleeve 10 in the direction of the longitudinal axis XX in a vacuum using an electron beam. By means of beam deflection without inertia (in the case of so-called multi-beam strategies), a plurality of parallel melting zones can be generated, whereby a plurality of valve sleeves 3 can also be produced simultaneously. Alternatively, a plurality of electron beams can be provided on the cylinder sleeve 10 with the injector head 11. In the case of electron beam additive manufacturing (EBM), the powder bed consists of a spherical powder having a particle size of 45 μm to 105 μm. It is advantageous for this method if the cylinder sleeve 10 and the metal powder are made of non-magnetic raw materials. This is because the magnetic raw material deflects the electron beam.

  As an alternative to electron beam additive manufacturing (EBM), selective laser additive manufacturing (SLM), which is also based on a powder bed, can be applied. In this method, the injector head 11 is provided in a layered manner on the cylinder sleeve 10 by a squeegee in the direction of the longitudinal axis XX, and subsequently is locally melted using a laser. This process is performed under an inert gas atmosphere. The spherical powder forming the powder bed usually has a particle size of 10 μm to 45 μm. The raw material is preferably a nickel-base alloy, an aluminum alloy, a titanium alloy or a conventional tool steel.

The speed with which the injector head 11 is formed on the cylinder sleeve 10 depends on the selection of the raw material of the injector head 11. Fast formation of an additional manufacturing process is normally expressed as volume per time, for example, ^{1cm 3} / ^h~50cm 3 / h. Therefore, in order to perform the manufacturing process at the lowest possible cost and effectively, the injector head 11 is configured smaller in volume than the cylinder sleeve 10. In order to perform the manufacturing process particularly effectively, a hollow space may be provided in the injector head 11.

  Following the additive manufacturing method, the valve sleeve 3 is removed from the clamping device and the residual powder is removed from the valve sleeve 3 using spray techniques.

  In particular, the functional aspects of the valve sleeve 3 can be completed in the last working step. Since the additive manufacturing method has been found to have a surface quality of Rz of about 30 μm to 150 μm and a dimensional accuracy of up to ± 0.25 mm, it is preferred that functional aspects, in particular the closure element seat 13, be used in the last manufacturing step. Post-processing is suggested. Therefore, the injector 1 is completely airtight and liquid tightly closed by the cooperation of the closing element 6 and the closing element seat 13.

  In particular in FIG. 4, the valve sleeve 3 can be seen. This valve sleeve 3 is manufactured according to the invention and has a complex geometry. For optimal spray formation of the medium 8, a plurality of flow pockets 20 distributed around the circumference and a plurality of curved injection holes 15 are formed in the injector head 11. Accordingly, the injection hole 15 has a flow passage that is bent along the longitudinal axis XX. The cross section of this flow passage may be circular, elliptical and / or polygonal.

  The valve sleeve 3 according to the invention can be used both for the inner valve-open injector 1 and for the outer valve-open injector 1.

  Therefore, according to the present invention, there is provided a valve sleeve 3 in which the injector head 11 may have a complicated and individually adjustable geometry, and at the same time can be manufactured at low cost and suitable for mass production. Can do. This allows for the best spread of spray when maximizing spray targets and optimal penetration.

Claims (10)

In the valve sleeve (3) of the injector (1) for injecting the medium (8), in particular for injecting fuel,
Comprising at least one cylinder sleeve (10) and an injector head (11);
The injector head (11) has a closing element seat (13) and at least one injection hole (15);
The valve sleeve (3), wherein the injector head (11) is processed using an additive manufacturing method and is attached to the cylinder sleeve (10) by material connection.   2. A feed region (12) having at least one flow pocket (20) and / or flow hole (21) is arranged in the injector head (10). Valve sleeve (3).   The valve sleeve (3) according to claim 2, characterized in that the supply region (12) comprises at least one web (22) supporting a closure element (6).   The valve sleeve (3) according to any one of the preceding claims, characterized in that the at least one injection hole (15) has a cylindrical or curved flow passage.   The said injector head (11) has at least 1 front | former step part (16) connected to at least 1 of the said injection holes (15), Any one of Claim 1 to 4 characterized by the above-mentioned. The valve sleeve (3) as described.   The injector head (11) is processed from a metal conductive weldable material using an electron beam additive manufacturing method (EBM), or the injector head (11) is a selective laser additive manufacturing method. 6. A valve sleeve (3) according to any one of claims 1 to 5, characterized in that it is processed from a metal weldable raw material by means of (SLM).   The valve sleeve (3) according to any one of claims 1 to 6, characterized in that the cylinder sleeve (10) is a rotationally symmetrical turning part made of a weldable metal raw material.   8. An injector (1), in particular a fuel injector, characterized in that it comprises a valve sleeve (3) according to any one of the preceding claims. A method of manufacturing an injector (1), in particular a fuel injector valve sleeve (3), comprising:
Providing a cylinder sleeve (10) formed from a rotationally symmetric turning portion;
Machining an injector head (11) having at least one injection hole (15) and a closure element seat (13) using an additional manufacturing method and attaching to the cylinder sleeve (10);
A method characterized by comprising:   The method according to claim 9, wherein the additive manufacturing method is a selective laser additive manufacturing method (SLM) or an electron beam additive manufacturing method (EBM).

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