EP2251541A1

EP2251541A1 - Fuel injector and fuel injection system

Info

Publication number: EP2251541A1
Application number: EP09006360A
Authority: EP
Inventors: Ileana Romeo; Matteo Soriani
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2009-05-11
Filing date: 2009-05-11
Publication date: 2010-11-17
Anticipated expiration: 2029-05-11
Also published as: EP2251541B1; ATE535706T1

Abstract

Fuel injector (18) including a central longitudinal axis (L) and being operable to be arranged in a cylinder head (14) of a combustion engine (22). The fuel injector (18) has an injector body (26) and an adjustment device (30). The adjustment device (30) comprises a ring element (32) being designed to be arranged in a recess (15) of a cylinder head (14) between the injector body (26) and the cylinder head (14) to align the fuel injector (18) relative to the recess (15) in radial direction, and a distance element (34). The distance element (34) is designed to be arranged in the recess (15) between the ring element (32) and the cylinder head (14) to level the fuel injector (18) relative to the cylinder head (14) in axial direction. Fuel-injection system with a cylinder head (14) and a fuel injector (18).

Description

The invention relates to a fuel injector and a fuel-injection system.
Fuel injectors are in wide spread use, in particular for internal combustion engines where they may be arranged in order to dose fuel into an intake manifold of the internal combustion engine or directly into the combustion chamber of a cylinder of the internal combustion engine. Fuel can be supplied to the internal combustion engine by the fuel injectors of the fuel-injection system.
The fuel injectors can be coupled to the cylinder head of the internal combustion engine in different manners. The coupling of the fuel injectors to the cylinder heads needs to be very precise to get a correct injection angle.
The object of the invention is to create a fuel injector for a cylinder head of a combustion engine which is simply to be manufactured and which facilitates a reliable and precise coupling between the fuel injector and the cylinder head of the combustion engine.
It is furthermore the object of the invention to create a fuel-injection system that ensures a precise dosing of fuel.
The objects are achieved by the features of the independent claims. Advantageous embodiments of the invention are given in the sub-claims.
According to a first aspect the invention is distinguished by a fuel injector including a central longitudinal axis and being operable to be arranged in a cylinder head of a combustion engine. The fuel injector has an injector body and an adjustment device. The adjustment device comprises a ring element being designed to be arranged in a recess of a cylinder head between the injector body and the cylinder head to align the fuel injector relative to the recess in radial direction, and a distance element. The distance element is designed to be arranged in the recess between the ring element and the cylinder head to level the fuel injector relative to the cylinder head in axial direction.
This has the advantage that for every adjustment device the same ring element can be used. The leveling of the fuel injector relative to the cylinder head can be carried out by distance elements with different axial extensions. Consequently, a simple production of the distance element is possible.
In an advantageous embodiment the distance element is a washer with a given thickness. By this the leveling of the fuel injector relative to the cylinder head can be carried out by using distance elements with different thickness.
In a further advantageous embodiment the distance element is of a material comprising a plastic. By this a good contact between the distance element and the cylinder head is possible. Furthermore, little adhesion between the distance element and the cylinder head during lifetime can be obtained. Consequently, simple service operations are possible. Additionally, a low noise due to contact between the fuel injector and the cylinder head can be obtained.
In a further advantageous embodiment the distance element is of a material comprising at least one of a polyphenylene sulfide, a polybutylene terephthalate and a polyethylene terephthalate. This has the advantage that PPS, PBT and PET are very hard and robust plastics.
In a further advantageous embodiment a retaining element is fixedly coupled to the injector body and is extending radially outward from the injector body in a manner that the retaining element is in interference with the distance element in radial direction. By this the retaining element can remove the distance element and/or the ring element from the recess in the case of disassembling.
In a further advantageous embodiment the retaining element is coupled to the injector body by an interference fit. This has the advantage that no further processing of the injector body is necessary to couple the retaining element to the injector body. Furthermore, a simple stamping process for the retaining element is possible.
According to a second aspect the invention is distinguished by a fuel-injection system with a cylinder head of an internal combustion engine and a fuel injector according to the first aspect of the invention. The fuel injector is arranged in a recess of the cylinder head.
Exemplary embodiments of the invention are explained in the following with the aid of schematic drawings. These are as follows:

Figure 1 an internal combustion engine in a schematic view,
Figure 2 a fuel injector and a cylinder head in a schematic view, and
Figure 3 the fuel injector with an adjustment device.

Elements of the same design and function that occur in different illustrations are identified by the same reference character.
Figure 1 shows an internal combustion engine 22, with an intake air tract 10, a motor block 12, a cylinder head 14 and an exhaust gas tract 16. In the motor block 12 a combustion chamber 20 is arranged.
The cylinder head 14 comprises one or more recesses 15 in which at least one fuel injector 18 and at least one sparking plug 19 are arranged. The injector body 26 is at least partially in engagement with the recess 15. An adjustment device 30 is arranged in the recess 15 and enables the adjustment of the fuel injector 18 relative to the cylinder head 14 of the combustion engine 22.
The fuel injector 18 (Figures 2 and 3) comprises an injector coupling portion 24 and a valve assembly 27. The injector coupling portion 24 is designed to be coupled to a highpressure fuel chamber of the internal combustion engine 22, the fuel is stored under high pressure, for example, under the pressure of about 200 bar in the case of a gasoline engine or of more than 2,000 bar in the case of a diesel engine.
Furthermore, the injector coupling portion 24 is designed to be coupled to an electrical supply to actuate a not shown actuator unit of the fuel injector 18.
The fuel injector 18 comprises a valve body 26 with a central longitudinal axis L and a not shown cavity which is axially led through the valve body 26. The fuel injector 18 further comprises a not shown valve needle taken in the cavity of the valve body 26. On a free end of the fuel injector 18 an injection nozzle 28 is formed which is closed or opened by an axial movement of the valve needle. In a closing position a fuel flow through the injection nozzle 28 is prevented. In an opening position fuel can flow through the injection nozzle 28 into the combustion chamber 20 of the internal combustion engine 22.
As can be best seen in Figure 3 the adjustment device 30 comprises a ring element 32 and a distance element 34 extending in the direction of the central longitudinal axis L.
The ring element 32 has a spherical surface 36 facing the central longitudinal axis L. The spherical surface 36 is designed to be arranged circumferentially over the ring element 32. Due to the spherical surface 36 the fuel injector 18 can be aligned in radial direction relative to the recess 15. The spherical surface 36 of the ring element 32 acts as a centering unit for the fuel injector 18 in the recess 15.
Preferably, the distance element 34 is shaped as a washer and has a given thickness T in axial direction. Depending on the thickness T of the distance element 34 the axial position of the fuel injector 18 relative to the cylinder head 14 can be adjusted.
The distance element 34 is of a material which comprises a plastic. A plastic enables a good contact between the distance element 34 and the cylinder head 14. Furthermore, only little adhesion between the distance element 34 and the cylinder head 14 during the lifetime of the fuel injector 18 can be obtained. Therefore, it is possible that the necessary services as for example a disassembling of the fuel injector 18 from the cylinder head 14 can be carried out very simple. Plastics achieve a low noise emission due to a contact between the fuel injector 18 and the cylinder head 14. In a preferred embodiment, the distance element 34 is of a material comprising a polyphenylene sulfide (PPS). PPS is a very hard and robust plastic. In further preferred embodiments, the distance element 34 is of a material which comprises at least one of a polybutylene terephthalate and a polyethylene terephthalate.
Furthermore, the adjustment device 30 has a retaining element 38 which is fixedly coupled to the injector body 26. Preferably, the retaining element 38 is of a material which comprises a plastic. Preferably, the retaining element 38 is coupled to the injector body 26 by an interference fit. This has the advantage that no further machining of the valve body 26 is necessary. The retaining element 38 is extending in radial direction from the injector body 26. The maximum radial extension of the retaining element 38 is at least as large as the inner diameter of the distance element 34. By this the retaining element 38 is in radial interference with the distance element 34.
In the following, the assembly and disassembly of the fuel injector 18, the adjustment device 30 and the cylinder head 14 of the combustion engine 22 will be described:

For assembling the fuel injector 18 with the ring element 32, the distance element 34 and the retaining element 38 is inserted into the recess 15 of the cylinder head 14 in an inserting direction D. The ring element 32 with the symmetric spherical surface 36 enables an exact positioning of the fuel injector 18 relative to the cylinder head 14 in particular in radial direction. The distance element 34 enables an exact positioning of the fuel injector 18 relative to the cylinder head 14 in axial direction. The axial position of the fuel injector 18 is depending on the thickness T of the distance element 34

If the fuel injector 18 shall be removed from the cylinder head 14, the fuel injector 18 with the ring element 32, the distance element 34 and the retaining element 38 can be pulled out from the recess 15 in the cylinder head 14 in a direction opposite to the inserting direction D. As the adhesion between the distance element 34 and the cylinder head 14 is small, the fuel injector 18 can be pulled out from the recess 15 very simple. As the retaining element 38 is in radial interference with the distance element 34, the retaining element 38 can come into engagement with the distance element 34 and/or the ring element 32. Therefore, the distance element 34 and the ring element 32 can be moved out from the recess 15.
As has been shown, the construction of the adjustment device 30 allows an exact alignment of the fuel injector 18 relative to the cylinder head 14 and a fast and simple disassembly of the fuel injector 18 from the cylinder head 14.

Claims

Fuel injector (18) including a central longitudinal axis (L) and being operable to be arranged in a cylinder head (14) of a combustion engine (22), the fuel injector (18) having an injector body (26) and an adjustment device (30), the adjustment device (30) comprising
- a ring element (32) being designed to be arranged in a recess (15) of a cylinder head (14) between the injector body (26) and the cylinder head (14) to align the fuel injector (18) relative to the recess (15) in radial direction, and

- a distance element (34) being designed to be arranged in the recess (15) between the ring element (32) and the cylinder head (14) to level the fuel injector (18) relative to the cylinder head (14) in axial direction.
Fuel injector (18) in accordance with claim 1, wherein the distance element (34) is a washer with a given thickness (T).
Fuel injector (18) in accordance with claim 1 or 2,
wherein the distance element (34) is of a material comprising a plastic.
Fuel injector (18) in accordance with one of the preceding claims, wherein the distance element (34) is of a material comprising at least one of a polyphenylene sulfide, a polybutylene terephthalate and a polyethylene terephthalate.
Fuel injector (18) in accordance with one of the preceding claims, wherein a retaining element (38) is fixedly coupled to the injector body (26) and is extending radially outward from the injector body (26) in a manner that the retaining element (38) is in interference with the distance element (34) in radial direction.
Fuel injector (18) in accordance with claim 5, wherein the retaining element (38) is coupled to the injector body (26) by an interference fit.
Fuel-injection system with a cylinder head (14) of an internal combustion engine (22) and a fuel injector (18) according to one of the preceding claims, wherein the fuel injector (18) is arranged in a recess (15) of the cylinder head (14).