Fuel injector

Abstract

A fuel injector is described which is able to be preassembled in a receiving opening of a fuel-distributor line in a loss-proof manner in a structural unit in the form of a fuel charge assembly for transport to the final assembly at the vehicle manufacturer. A radial support disk for preventing the loss of the fuel injector is disposed on the inflow-side end of the inlet pipe by press-fitting the radial support disk in the receiving opening. The fuel injector is particularly suitable for the direct injection of fuel into a combustion chamber of a mixture-compressing internal combustion engine having externally supplied ignition.

Claims

1. A fuel injector for a fuel-injection system of internal combustion engine, comprising: a valve needle; a valve-closure body; a valve-seat surface; an actuator whose excitation is configured to provide a lifting motion of the valve needle to allow for an actuation of the valve-closure body which forms a sealing seat together with the valve-seat surface; an inflow-side inlet pipe for a supply of fuel; and a radial support disk for preventing a loss of the fuel injector in an installed state, the radial support disk being situated on an inflow-side end of the inlet pipe; wherein the radial support disk is at an outer circumference of the radial support disk with alternating press-fitting regions that project outward and radially recessed regions, wherein the press-fitting regions of the radial support disk extend either across a portion of a height of the radial support disk or across the entire height of the radial support disk, and wherein the radial support disk is interrupted by a slot which extends across the radial support disk in an axial direction.

2. The fuel injector as recited in claim 1, wherein the fuel injector is for direct injection of fuel into the combustion chamber of the internal combustion engine.

3. The fuel injector as recited in claim 1, wherein the inlet pipe includes a sealing ring which surrounds the inlet pipe, and wherein the radial support disk is disposed upstream from the sealing ring when viewed in a flow direction.

4. The fuel injector as recited in claim 3, wherein an end collar is on the inflow-side end of the inlet pipe, and the radial support disk at least partially clasps the end collar from above and below the end collar.

5. The fuel injector as recited in claim 4, wherein multiple tabs are formed on the radial support disk distributed across the circumference, which project radially inward from a base body ring.

6. The fuel injector as recited in claim 5, wherein the multiple tabs include tabs formed starting from an upper side of the radial support disk, and additional tabs provided starting from a lower side of the radial support disk, which project radially farther inward than the tabs.

7. The fuel injector as recited in claim 6, wherein the tabs and the additional tabs are at an offset from one another when viewed across the circumference.

8. The fuel injector as recited in claim 1, wherein the radial support disk is a thin, compact disk, which is made from plastic or from a metal.

9. The fuel injector as recited in claim 8, wherein the radial support disk is made from PEEK or PPS or POM.

10. The fuel injector as recited in claim 8, wherein the radial support disk is made from aluminum.

11. The fuel injector as recited in claim 1, wherein the inlet pipe has a conically extending section.

12. A fuel-injection device, comprising: a fuel injector for a fuel-injection system of internal combustion engine, the fuel injector including valve needle, a valve-closure body, a valve-seat surface, an actuator whose excitation is configured to provide a lifting motion of the valve needle to allow for an actuation of the valve-closure body which forms a sealing seat together with the valve-seat surface, an inflow-side inlet pipe for a supply of fuel, and a radial support disk for preventing the loss of the fuel injector in an installed state, the radial support disk being situated on an inflow-side end of the inlet pipe, wherein the radial support disk is at an outer circumference of the radial support disk with alternating press-fitting regions that project outward and radially recessed regions, wherein the press-fitting regions of the radial support disk extend either across a portion of a height of the radial support disk or across the entire height of the radial support disk, and wherein the radial support disk is interrupted by a slot which extends across the radial support disk in an axial direction; and a fuel-distributor line having at least one connection fitting having a receiving opening for the fuel injector, the inlet pipe of the fuel injector being preassembled in a loss-proof manner by press-fitting the radial support disk in the receiving opening.

13. The fuel injection device as recited in claim 12, wherein the fuel injector includes an intermediate element, which is used as a damping element and/or a decoupling element, and which is inserted between a step of a valve housing or a lower end face of a support element and a shoulder of a receiving bore, the shoulder extending at a right angle to a longitudinal extension of the receiving bore.

14. The fuel injection device as recited in claim 12, wherein in the radial support disk, the slot extends perpendicularly, and wherein the press-fitting regions extend across the entire component height, and the slot is eccentrically situated in one of three radially recessed regions.

15. The fuel injector as recited in claim 1, further comprising: an intermediate element, which is used as a damping element and/or a decoupling element, and which is inserted between a step of a valve housing or a lower end face of a support element and a shoulder of a receiving bore, the shoulder extending at a right angle to a longitudinal extension of the receiving bore.

16. The fuel injector as recited in claim 1, wherein in the radial support disk, the slot extends perpendicularly, and wherein the press-fitting regions extend across the entire component height, and the slot is eccentrically situated in one of three radially recessed regions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the present invention are shown in simplified form in the figures and described in greater detail below.

(2) FIG. 1 shows a partially illustrated fuel-injection device in a conventional configuration.

(3) FIG. 2 shows a first hydraulic interface in the region of a receiving opening of the fuel-distributor line.

(4) FIG. 3 shows a second hydraulic interface in the region of a receiving opening of the fuel-distributor line.

(5) FIG. 4 shows a schematic force distribution of the radial force at the conically extending wall of the inlet pipe according to FIG. 3.

(6) FIG. 5 shows a hydraulic interface in the region of a receiving opening of the fuel-distributor line to a radial support disk according to the present invention.

(7) FIG. 6 shows a simplified sectional view through the radial support disk along line VI-VI in FIG. 5.

(8) FIG. 7 shows a first development of a radial support disk according to the present invention in a perspective view.

(9) FIG. 8 shows a second development of a radial support disk according to the present invention in a perspective view.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(10) For a better understanding of the present invention, a conventional fuel-injection device is described in greater detail below on the basis of FIG. 1. FIG. 1 shows as an exemplary embodiment a valve in the form of a fuel injector 1 for fuel-injection systems of mixture-compressing internal combustion engines having externally supplied ignition, in a side view. Fuel injector 1 is part of the fuel-injection device. Via a downstream end, fuel injector 1, which is developed in the form of a directly injecting fuel injector for the direct injection of fuel into a combustion chamber 250 of the internal combustion engine, is installed in a receiving bore 20 of a cylinder head 9. A sealing ring 2, in particular made of Teflon, provides for optimum sealing between fuel injector 1 and the wall of receiving bore 20 of cylinder head 9.

(11) An intermediate element 24, which is used as a damping or decoupling element, for example, is inserted between a step 21 of a valve housing 22 (not shown) or a lower end face 21 of a support element 19 (FIG. 1) and a shoulder 23 of receiving bore 20, the shoulder extending at a right angle to the longitudinal extension of receiving bore 20, for example. Such an intermediate element 24 is also used to compensate for production and installation tolerances and to ensure support that is free of transverse forces even if fuel injector 1 is positioned at a slight tilt.

(12) On its inflow-side end 3, fuel injector 1 has a plug connection to a fuel-distributor line (fuel rail) 4, which is sealed by a sealing ring 5 between a connection fitting (rail cup) 6 of fuel-distributor line 4, which is shown in a sectional view, and an inlet pipe 7 of fuel injector 1. Fuel injector 1 is inserted into a receiving opening 12 of connection fitting 6 of fuel-distributor line 4. Connection fitting 6 emerges from actual fuel-distributor line 4 in one piece, for instance, and has a flow opening 15 with a smaller diameter upstream from receiving opening 12, via which the flow approaches fuel injector 1. Fuel injector 1 is provided with an electric connector plug 8 for the electrical contacting for the actuation of fuel injector 1.

(13) Electric connector plug 8 is connected via corresponding electrical lines to an actuator (not shown here) whose excitation makes it possible to achieve a lifting motion of a valve needle, thereby allowing for an actuation of a valve closure body which forms a sealing seat together with a valve-seat surface. These latter components are not explicitly illustrated and may have any already conventional designs. For example, the actuator is able to be operated in an electromagnetic, piezoelectric or magneto-restrictive manner.

(14) To set fuel injector 1 and fuel-distributor line 4 apart from each other free of radial forces for the most part and to reliably retain fuel injector 1 in receiving bore 20 of cylinder head 9, a hold-down device 10 is provided between fuel injector 1 and connection fitting 6. Hold-down device 10 is developed in the form of a clip-shaped component, e.g., as a punched and bent part. Hold-down device 10 has a partially ring-shaped base element 11 from which a hold-down clip 13 extends at an angle, which rests against fuel-distributor line 4 at a downstream end face 14 of connection fitting 6 in the installed state.

(15) To allow for an installation of fuel injectors 1 in receiving bores 20 of cylinder head 9, they usually have to be supplied to the engine or vehicle manufacturer for assembly. In an advantageous manner, this supply takes the form of a compact structural unit, known as a fuel charge assembly, which is made up of fuel-distributor line 4 and fuel injectors 1 already preassembled in receiving openings 12. It has to be ensured here that after the preassembly on fuel-distributor line 4, fuel injectors 1 remain there without getting lost until the installation on cylinder head 9. In the preassembled state, i.e. in the state in which the fuel charge assembly is supplied to the customer for the engine assembly, fuel injector 1 is not yet in the final position in receiving opening 12 but projects farther from receiving opening 12 than in the final assembly position because hold-down device 10 has not been tensioned yet.

(16) An object of the present invention is to ensure that fuel injectors 1 safely and reliably remain in receiving openings 12 of fuel-distributor line 4 during the entire time from the preassembly to the final assembly. Vibrations or accelerations and the application of forces during transport and handling of the fuel charge assembly during the preassembly and the final assembly at the vehicle manufacturer constitute different danger sources for an accidental detachment of fuel injectors 1 from receiving openings 12 of fuel-distributor line 4, which can be completely ruled out according to the present invention.

(17) FIGS. 2 and 3 show hydraulic interfaces in the region of receiving openings 12 of fuel-distributor line 4, the structure shown in FIG. 2 being similar to that of FIG. 1. In this development, inlet pipe 7 of fuel injector 1 has a cylindrical shape. Sealing ring 5 is clamped between the inner wall of receiving opening 12 and inlet pipe 7. In addition, a support ring 25 is provided underneath sealing ring 5, which is supported on a shoulder 26 of inlet pipe 7, for example. Fuel injector 1 is radially supported via support ring 25. Slippage of sealing ring 5 is impossible in this way. For that reason, the press-fitting of sealing ring 5 is also not affected either.

(18) In contrast to the development of the hydraulic interface in the region of receiving opening 12 of fuel-distributor line 4 of FIG. 2, a conically extending section is provided in the case of inlet pipe 7 of fuel injector 1 shown in FIG. 3, which is surrounded by support ring 25 via an also conically extending inner opening and partially by sealing ring 5. Because of a force division of the radial force at the conically extending wall of inlet pipe 7, possibly also into an axial force component (see schematic illustration in FIG. 4), there is the risk of unilateral slipping of sealing ring 5 in the upward direction, away from the conical section, if the axial force of support ring 25 is greater than the displacement force of sealing ring 5. This slippage could be accompanied by a reduced compression of sealing ring 5. In the presence of vibrations or the back-and-forth movements of fuel injector 1 during transport, this may happen in alternation on different sides across the circumference of the inner wall of receiving opening 12, which means that there is a risk of fuel injector 1 becoming loose in receiving opening 12.

(19) FIG. 5 shows a partially illustrated fuel-injection device having a first fuel injector 1 according to the present invention. In this embodiment of fuel injector 1, it has on its inflow-side end 3 in the region of an end collar 29 a radial support disk 30 according to the present invention, which serves as a loss prevention. Radial support disk 30 is developed in the form of a thin but compact disk, which may be made from plastic (e.g., PEEK, PPS, POM) or a metal (e.g., aluminum). Radial support disk 30 is axially mounted from above on fuel injector 1 such as with the aid of a locating pin. Alternatively, radial support disk 30 is able to be mounted using a spread gripper or a similar tool. In that regard, radial support disk 30 is disposed still upstream from sealing ring 5 when viewed in the flow direction.

(20) FIG. 6 shows a simplified sectional view through radial support disk 30 along line VI-VI in FIG. 5. This representation is mainly meant to illustrate that radial support disk 30 is provided at its outer circumference with alternating press-fitting regions 31 that project farther outward and radially recessed regions 32.

(21) A first embodiment of a radial support disk 30 according to the present invention is shown in a perspective view in FIG. 7. Radial support disk 30 has a planar upper and lower side. The geometry of radial support disk 30 is characterized in that multiple tabs 33, 34 are formed across the circumference, which project radially inward from a base body ring. Multiple tabs 33 are formed starting from the upper side of radial support disk 30, while additional tabs 34 are provided starting from the lower side of radial support disk 30, which project radially farther inward. As shown in FIG. 7, tabs 33 and 34 may be developed at an offset from one another viewed across the circumference. Tabs 33, 34 have inner limiting surfaces, which extend either at a right angle, i.e., in an axially parallel manner, or in an oblique manner or, ideally, as may be gathered from FIG. 7, feature a bevel that extends out of a perpendicular limiting surface. Tabs 33, 34 ensure that radial support disk 30 safely and reliably remains on inlet pipe 7 because of the created undercut on the existing geometry of end collar 29 of inlet pipe 7. Tabs 33 on the upper side have to be able to absorb the corresponding assembly forces. In addition, tabs 33 on the upper side must also be able to absorb hydraulic forces during the operation and during the initial filling of the system. Tabs 34 on the lower side have to be able to withstand the corresponding disassembly forces (after ageing across the service life inside the respective fuel).

(22) In the embodiment shown in FIG. 7, radial support disk 30 has been provided with a slot 35, which extends at a right angle in a first axial subsection and extends at an angle in a second axial subsection. This embodiment variant is particularly advantageous because radial support disks 30 are able to be handled as bulk material without getting entangled with one another. However, slot 35 may also have an oblique extension throughout. It is even possible to omit slot 35 altogether if the material of radial support disk 30 has sufficient elasticity. As a rule, a slot 35 in radial support disk 30 will be required for assembly-related reasons. Slot 35 makes it much easier to install radial support disk 30 on end collar 29 of inlet pipe 7 because the material of radial support disk 30 is subjected to considerably lower strain loads in comparison to an unslotted variant.

(23) In its press-fitting regions 31 that project radially farthest outward, radial support disk 30 has a larger outer diameter than the inner diameter of receiving opening 12 of fuel-distributor line 4. As a consequence, radial support disk 30 is inserted under pressure during the preassembly of fuel injector 1 in receiving opening 12, the assembly being made easier by slot 35, and a tolerance compensation being possible. In the illustrated exemplary embodiment, press-fitting regions 31 extend only across a portion of the component height, i.e., only across the lower half of the component height in this instance. The radially recessed regions 32 form through-flow pockets, which are meant to prevent radial support disk 30 from being bent down by end collar 29 of inlet pipe 7 during the initial filling with fuel and from exerting pressure on sealing ring 5.

(24) A second embodiment of a radial support disk 30 according to the present invention is shown in a perspective view in FIG. 8. This radial support disk 30 differs from radial support disk 30 according to FIG. 7 in that a perpendicularly extending slot 35 is provided, the press-fitting regions 31 extend across the entire component height, and slot 35 is eccentrically situated in one of the three radially recessed regions 32.

(25) The individual geometrical features illustrated on radial support disks 30 of FIGS. 7 and 8 may also always be combined with one another.