Injection valve

Abstract

The invention relates to an injection valve (10), in particular a fuel injector (12), comprising a valve body (14), in which a valve closing member (30) is liftably arranged, and comprising a sealing seat (32) formable between the valve body (14) and the valve closing member (30) for exposing or blocking a passage for a pressurised medium in the direction of at least one outlet opening (44; 44a to 44c), wherein the at least one outlet opening (44; 44a to 44c) has a hole axis (50; 50a to 50c) which preferably intersects a longitudinal axis (16) of the valve closing member (30), wherein the valve body (14) or a nozzle cap element (22) connected to the valve body (14) has an inner contour (36), in the region of which the at least one outlet opening (44; 44a to 44c) is formed.

Description

[0001] Description

[0002] Injector

[0003] Technical area

[0004] The invention relates to an injection valve, in particular a fuel injector for injecting alternative fuels, which is characterized by a particularly advantageous arrangement of outlet openings for a pressurized medium, which is possible over a wide range of possible arrangements.

[0005] State of the art

[0006] From DE 10 2015 211 769 A1 by the applicant, an injection valve is known which has a valve body with a plurality of outlet openings that can be closed by means of an approximately spherical valve closing member. The known injection valve has, in particular, a valve body whose inner contour is composed of a plurality of sections in the region of the outlet openings or in the region of a front end. In particular, the known injection valve has a curved first section that is arranged in the region of a longitudinal axis of the valve closing member, wherein the curvature projects towards the valve closing member. Adjacent to the first section, viewed in the radial direction in the direction of the longitudinal axis of the valve closing member, is a second section that is inclined, wherein the outlet openings are formed in the region of the second section, radially directly adjacent to the first section.To release the outlet openings, the valve closing element, which forms a sealing seat in the region of the second section in a closed position, must be lifted from the second section. The known injection valve thus has an inward-opening valve closing element.

[0007] Disclosure of the invention Particularly in connection with new injection technologies that inject alternative, liquid fuels directly into a combustion chamber or into an intake tract of an internal combustion engine, it is necessary to arrange and design the outlet openings on the injector such that a desired injection quantity and shape of fuel sprays can be achieved. Due to the generally lower energy density of such alternative fuels compared to diesel fuel, it is necessary to realize a larger injection cross-section of the outlet openings for comparable engine power. In order to implement this (larger) injection cross-section while still achieving acceptable fuel preparation (atomization), a larger number of outlet openings is generally required than is usually the case with injectors used for compression-ignition internal combustion engines.Likewise, a certain minimum length of a spray-guiding jacket length of the exhaust opening is required in order to direct the fuel spray in the desired direction, especially under asymmetrical flow conditions due to oblique intersections of the outlet opening in the area of ​​the inner contour of the valve body. On the other hand, exhaust openings that are as short as possible can have a positive influence on the spray break-up behavior. The aim is therefore usually to achieve ratios between the diameter and the length of the exhaust opening in the range of less than or approximately 1:1. However, due to the spray steering requirements, these cannot always be achieved. A further requirement when using such injectors for alternative fuels is that the installation situation of the injectors often requires a well off-center arrangement in the cylinder head, which means that there is a large angular deviation between the longitudinal and radial directions.Hole axis of the outlet opening and the axis of the beam is required.

[0008] In view of the above explanations, the inventive injection valve with the features of claim 1 has the advantage that it meets the above-mentioned requirements in a particularly simple and advantageous manner. In particular, it enables a universal or widely possible arrangement of outlet openings for the fuel to be atomized for a wide variety of applications, with favorable flow conditions and the achievement of large injection quantities. These advantages are achieved in an inventive injection valve with the features of claim 1 in that the injection valve has a valve body in which a valve closing member is arranged for lifting movement.Furthermore, a sealing seat that can be formed between the valve body and the valve closure member is provided for opening or blocking a passage for a pressurized medium in the direction of at least one outlet opening, wherein the at least one outlet opening has a hole axis that preferably intersects a longitudinal axis of the valve closure member. The valve body or a nozzle dome element connected to the valve body has a curved inner contour and a curved outer contour, in the region of which the at least one outlet opening is formed. In the region between the curved inner contour and the curved outer contour, the valve body or the nozzle dome element has a wall thickness that is constant or deviates by a maximum of + / - 20% from an average wall thickness.In addition, a normal applied to the hole axis of at least one outlet opening forms a tangent to the inner contour or has an angle of no more than 20° to the tangent. Finally, the sealing seat is arranged at an axial distance from the inner contour, viewed in the direction of the longitudinal axis of the valve closure member.

[0009] Advantageous further developments of the injection valve according to the invention are listed in the subclaims.

[0010] With regard to the geometry of the valve body or the nozzle dome element in the region of the at least one outlet opening, it is preferably provided that the inner contour and the outer contour are each formed in the shape of a circular arc, wherein their radii (r, R) preferably have a common radius center point (M).

[0011] In order to be able to adapt the injection valve to the respective requirement profile very easily by replacing only a few parts, particularly in connection with different applications or combustion engines, a particularly preferred design of the injection valve has the feature that the valve body is formed in at least two parts, viewed in the direction of the longitudinal axis, and that the inner contour is formed on a nozzle tip element. This nozzle tip element can advantageously be connected to a base body of the valve body by means of a union nut or similar component, whereby axial clamping and sealing are formed between the base body and the nozzle tip element.

[0012] Preferably, the valve closing member is designed as an outwardly opening valve closing member or is arranged to be movable in the direction of the at least one outlet opening in order to achieve the open position.

[0013] A particularly preferred geometry of the valve body or of the nozzle tip element is characterized in that the inner contour, starting from the longitudinal axis, viewed in the radial direction, has a curved or rectilinear first section, which is followed by a second curved section, in the region of which the at least one outlet opening is formed, wherein the curvature or inclination of the first section runs opposite to the curvature of the second section, so that the cross section of the valve body or of the nozzle tip element is Q-shaped in the region of the two sections.

[0014] When using a nozzle tip element, this is preferably designed as a machined turned part with a view to advantageous production.

[0015] The jet guidance is promoted in that the cross section of the at least one outlet opening increases towards the outside of the valve body, preferably in a step-like manner.

[0016] Finally, in a particularly preferred design for achieving advantageous flow properties, it is provided that the ratio between a diameter or a theoretical diameter of the at least one outlet opening and a jet-guiding surface line of the at least one outlet opening is between 1:0.75 and 1:2.5.

[0017] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings. Brief description of the drawings

[0018] Fig. 1 shows an axial end region of an injection valve according to the invention facing the combustion chamber of an internal combustion engine in a sectional view,

[0019] Fig. 2 shows a detail of Fig. 1 in the area of ​​an outlet opening in an enlarged view and

[0020] Fig. 3 to Fig. 5 each show, in a partial longitudinal section, different arrangements of outlet openings in the region of a nozzle tip element of the injection valve.

[0021] Embodiments of the invention

[0022] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0023] Fig. 1 shows a section of the axial end region of an injection valve 10 facing a combustion chamber (not shown) of an internal combustion engine. The injection valve 10 is designed as a fuel injector 12 and is used in particular, but not restrictively, for the use of alternative liquid fuels such as alcohols (methanol, ethanol) or ammonia. In addition to the use in which the fuel is injected (directly) into the combustion chamber of the internal combustion engine by means of the injection valve 10, the injection valve 10 can also alternatively be arranged such that it injects the fuel into an intake tract, i.e., in a region spaced apart from the combustion chamber of the internal combustion engine.

[0024] The injection valve 10 has a valve body 14, which, viewed in the direction of a longitudinal axis 16, is composed of at least two components. In particular, the valve body 14 consists of a valve base body 18 as the first component, and a nozzle tip element 22, which is clamped to the valve base body 18 in the axial direction by means of a union nut 20 or similar element, as the second component. The nozzle tip element 22 is designed as a turned part and is machined using machining processes.

[0025] The nozzle dome element 22 has, on the side facing the valve base body 18, a stepped recess 24 on its inside, into which a front end section 25 of the valve base body 18 is immersed. The valve base body 18 has, at the level of the recess 24, on the side facing the longitudinal axis 16, a radially circumferential sealing surface 26 which can interact with a valve seat surface 28 of a valve closing member 30. In the closed position of the valve closing member 30 shown in Fig. 1, the longitudinal axis of which is aligned with the longitudinal axis 16, the valve seat surface 28, together with the sealing surface 26 on the valve base body 18, forms a sealing seat 32 in order to prevent the pressurized fuel from being injected into the combustion chamber or intake tract of the internal combustion engine.

[0026] In the open position not shown in Fig. 1, the valve closing member 30 is moved by an actuator (not shown) in the direction of arrow 34 toward the nozzle tip element 22 to enable fuel injection. The valve closing member 30 is thus designed as an outwardly opening valve closing member 30.

[0027] The nozzle dome element 22 has an inner contour 36 which, viewed in the direction of the longitudinal axis 16, is arranged at a distance from the sealing seat 32 and is composed of at least two sections 38, 40. The first section 38, which directly surrounds the longitudinal axis 16, is curved, preferably in the shape of a circular arc with a first radius n. The second section 40, which immediately radially surrounds the first section 38, is also curved, preferably also in the shape of a circular arc with a second radius r. The radius r is preferably smaller than the radius n. The curvature of the first section 38 projects in the direction of the valve closing member 30, while the curvature of the second section 40 is arranged in the opposite direction. Mathematically speaking, an inflection point is thus formed between the two sections 38, 40.It should also be noted that at least one of the two sections 38, 40 can have any desired curved shape instead of a circular arc. The first section 38 can also be straight.

[0028] It is essential that in the transition area 42 between the two sections 38, 40 no edge or kink is formed radially around the longitudinal axis 16, ie that the transition area 42 is formed without edges or kink.

[0029] Preferably in the region of the second section 40, but alternatively or additionally also in the region of the first section 38, at least one outlet opening 44 for injecting the fuel is formed. As can be seen in particular from Fig. 2, the at least one outlet opening 44 has a first bore section 46 and a second bore section 48. The first bore section 46 has, for example, a diameter di, and the second bore section 48 has a diameter d2, wherein the diameter d2 of the second bore section 48 is greater than the diameter di of the first bore section 46. The first bore section 46 of the outlet opening 44, with its surface line viewed in the direction of a hole axis 50 of the outlet opening 44, forms a jet guidance section 52 for the fuel jet, the length I of which, in relation to the diameter di of the first bore section 46, is between 1:0.75 and 1:2.5.

[0030] As can be seen particularly from Fig. 2, a normal N applied to the hole axis 50 in the region of the first section 38 on the inner contour 36 simultaneously forms a tangent T on the inner contour 36 in the region of the outlet opening 44. However, it is also conceivable that an angle of up to 20° is formed between the normal N and the tangent T. Furthermore, it can be seen particularly from Fig. 1 that the hole axis 50 intersects the longitudinal axis 16.

[0031] 1 and 2 together, it can also be seen that the nozzle tip element 22 has a curved outer contour 51 and a wall thickness d which is at least almost constant at least in the region of the two bore sections 38, 40 of the inner contour 36, but deviates by a maximum of + / - 20% from an average wall thickness d of the nozzle tip element 22 in the region of the two sections 38, 40. As a result, the nozzle tip element 22 forms a Q-shape in the region of the two sections 38, 40. In the illustrated embodiment, the outer contour 51 is designed in the shape of a circular arc with a radius R, wherein the radius centers of the second section 40 of the inner contour 36 and the outer contour 51 intersect at a point M.

[0032] Figs. 3 to 5 show different arrangements of outlet openings 44a, 44b, and 44c, respectively. The outlet opening 44a in Fig. 3 is arranged, as in Figs. 1 and 2, in the region of the second section 40 of the inner contour 36. As a result, the hole axis 50a of the outlet opening 44 intersects the longitudinal axis 16 in a region within the injection valve 10.

[0033] In Fig. 4, the outlet opening 44b is arranged in the second section 40 such that the hole axis 50b runs at least approximately parallel to the longitudinal axis 16. Finally, Fig. 5 shows the case in which the hole axis 50c of the outlet opening 44c intersects the longitudinal axis 16 of the valve body 14 in a region below the nozzle dome element 22.

[0034] The injection valve 10 described so far can be modified or altered in a variety of ways without deviating from the inventive concept. For example, it is conceivable to design the valve base body 18 and the nozzle tip element 22 as a monolithic component. The invention is also not intended to be limited to outward-opening valve closing members 30. Furthermore, the shape of the outlet opening 44, 44a to 44c is not limited to round cross-sections. In the event that the cross-section of the outlet opening 44 is polygonal, for example, the cross-sectional area must be converted to a theoretical round diameter d with regard to the ratio l / di described above.

Claims

Claims 1. Injection valve (10), in particular a fuel injector (12), with a valve body (14) in which a valve closing member (30) is arranged so as to be movable in stroke, with a sealing seat (32) which can be formed between the valve body (14) and the valve closing member (30) for opening or blocking a passage for a pressurized medium in the direction of at least one outlet opening (44; 44a to 44c), wherein the at least one outlet opening (44; 44a to 44c) has a hole axis (50; 50a to 50c) which preferably intersects a longitudinal axis (16) of the valve closing member (30), wherein the valve body (14) or a nozzle dome element (22) connected to the valve body (14) has a curved inner contour (36) and a curved outer contour (51), in the region of which the at least one outlet opening (44;44a to 44c) is designed such that the valve body (14) or the nozzle dome element (22) has a wall thickness (d) in the area between the curved inner contour (36) and the curved outer contour (51) which is constant or deviates by a maximum of + / - 20% from an average wall thickness (d), that a normal (N) applied to the hole axis (50; 50a to 50c) of the at least one outlet opening (44; 44a to 44c) forms a tangent to the inner contour (36) or has an angle of a maximum of 20° to the tangent, and that the sealing seat (32) is arranged at an axial distance from the inner contour (36) when viewed in the direction of the longitudinal axis (16) of the valve closing member (30); 2. Injection valve according to claim 1, characterized in that the inner contour (36) and the outer contour (51) are each circularly arc-shaped, wherein their radii (r, R) preferably have a common radius center point (M).

3. Injection valve according to claim 1 or 2, characterized in that the valve body (14) is formed in at least two parts when viewed in the direction of the longitudinal axis (16), and that the inner contour (36) is formed on a nozzle dome element (22).

4. Injection valve according to claim 3, characterized in that the nozzle dome element (22) is connected to a valve base body (16) of the valve body (14) by means of a union nut (20) or the like.

5. Injection valve according to one of claims 1 to 4, characterized in that the valve closing member (30) is designed as an outwardly opening valve closing member (30) or, to form the passage for the medium, the valve closing member (30) is arranged to be movable in the direction of the at least one outlet opening (44; 44a to 44c).

6. Injection valve according to one of claims 1 to 5, characterized in that the inner contour (36), starting from the longitudinal axis (16), viewed in the radial direction, has a curved or rectilinear first section (38), which is adjoined by a second curved section (40), in the region of which the at least one outlet opening (44; 44a to 44c) is formed, wherein the curvature or inclination of the first section (38) runs opposite to the curvature of the second section (40), so that the cross section of the valve body (14) or of the nozzle dome element (22) is Q-shaped in the region of the two sections (38, 40).

7. Injection valve according to one of claims 1 to 6, characterized in that the nozzle dome element (22) is designed as a machined turned part.

8. Injection valve according to one of claims 1 to 7, characterized in that that the cross-section of the at least one outlet opening (44; 44a to 44c) increases in the direction toward the outside of the valve body (14), preferably in a step-like manner.

9. An injection valve according to one of claims 1 to 8, characterized in that the ratio between a diameter (di) or a theoretical diameter (di) of the at least one outlet opening (44; 44a to 44c) and a spray-guiding surface line of the at least one outlet opening (44; 44a to 44c) is between 1:0.75 and 1:2.5.

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