Patent Application
20150136086
The present invention relates to a system, especially a fuel injection system, for the high-pressure injection in internal combustion engines, having a fuel distributor and multiple fuel injectors. In particular, the present invention pertains to the field of fuel-injection systems for mixture-compressing internal combustion engine featuring external ignition, in which fuel is injected directly into the combustion chambers of the internal combustion engine.
A fuel distributor rail and multiple fuel injectors disposed on the fuel distributor rail are discussed in European patent EP 2 151 572 A2. A collar-shaped element having tabs on both sides, which is placed around an upper fuel nipple of the fuel injector, is provided to connect the fuel injectors to the fuel distributor rail. In addition, a retaining clip is provided, which engages around a cylindrical body of an injector connection of the fuel distributor rail from above, along a longitudinal axis, the tabs of the collar engaging with openings of the retaining clip. This fastens the fuel injector to the cylindrical body of the injector connection.
The design from the European patent 2 151 572 A2 has the disadvantage that, during operation, the fuel distributor rail can be excited to vibrations in the audible frequency range. This is due to noise sources in the fuel injectors, in particular. The structure-borne noise, for example, spreads from the fuel injectors, via the injector connections, the fuel distributor rail and the rail holders, in certain cases also to the add-on structure, from where interfering noise is radiated. These interfering noises may possibly even reach the interior of the vehicle.
The system according to the present invention having the features described herein has the advantage of ensuring improved vibrational damping. More specifically, it is advantageous that vibrations that arise in particular in the region of the fuel injectors are able to be effectively damped with regard to a transmission to the fuel distributor, so that interfering noise is reduced.
The measures set forth in the dependent claims enable advantageous developments of the system described herein.
The system is especially suitable for internal combustion engines featuring direct gasoline injection. The fuel distributor may be configured as a fuel distributor rail for this purpose. The fuel distributor stores fuel under high pressure and distributes the fuel among the plurality of fuel injectors, which are configured as high pressure fuel injectors, in particular. The fuel required for the combustion process is then injected by the fuel injectors into the respective combustion chamber of the internal combustion engine under high pressure. The fuel is compressed by a high-pressure pump and conveyed in controlled quantities into the fuel distributor via a high-pressure line.
The system may advantageously be configured as a fuel-injection system for the high-pressure injection in internal combustion engines, and the fuel distributor may be connected to an add-on structure in a suitable manner. The add-on structure may be the cylinder head of the internal combustion engine. A connection via spacer sleeves or via additional connection elements is possible as well.
The fuel injectors may be suspended on the cups, so to speak. Especially a gimbal-type mounting on the cups is possible. The holding element may be developed as a U-shaped clip, in particular. The holding element transmits the quasi-static forces. At the same time, the holding element assumes the function of ensuring that the relative deflection of a fuel injector in relation to the associated cup under the effect of operating forces remains under a defined limit value, so that an O-ring seal is protected from wear.
In addition, a vibration-related decoupling and damping between the fuel injectors and the fuel distributor is achieved by the one or multiple damping layer(s), while the other requirements continue to be satisfied.
It is advantageous that the collar of the fuel injector is at least indirectly braced on the supporting surface of the holding element. This includes the possibility that the collar of the fuel injector is braced directly on the supporting surface of the holding element. However, it is especially advantageous that the collar of the fuel injector is braced on the holding element by way of the damping layer, which further improves the oscillation decoupling. More specifically, the collar of the fuel injector may be braced on the supporting surface of the holding element by way of the damping layer. The supporting surface of the holding element may thus ensure the bracing both of the cup and the collar of the fuel injector.
It is advantageous that the holding element has at least one holding section, the cup has a collar, and the holding section of the holding element clasps the collar of the cup from behind. In this context it is furthermore advantageous that the holding section is configured as a U-shaped bent holding section. This results in a compact design of the holding element. The holding element is thereby able to be configured as a retaining clip, in particular. The holding section of the holding element may rest directly against the collar of the cup. However, it is especially advantageous that the holding section of the holding element is braced on the collar of the cup by an additional damping layer. This further improves the damping of vibrations. However, it is also especially advantageous that the damping layer provided at the supporting surface also extends along the inside of the holding section of the holding element and that the holding section of the holding element is braced on the collar of the cup by the damping layer. The damping layer may thus act on both sides of the collar of the cup, so to speak.
In an advantageous manner, the damping layer or the further damping layer is based on a visco-elastic material. The damping layer or the further damping layer can advantageously be connected to the holding element. The connection may be configured using vulcanization, for instance. The visco-elastic material for the damping layer is able to be based on rubber, in particular. The term rubber should be taken quite generally in this case, and besides natural rubber also includes synthetic rubber materials.
It is also advantageous that the damping layer or the further damping layer is configured as a separate insertion part. This also ensures a modular development in which, depending on the individual case, a suitable damping layer or a further damping layer is combined with an appropriately configured holding element.
Exemplary embodiments of the present invention are explained in greater detail in the following description with reference to the attached drawing, in which corresponding elements have been provided with matching reference numerals.
Fuel distributor 2 has a plurality of cups 9, 10. Fuel injector 3 is disposed on cup 9, and fuel injector 4 is disposed on cup 10. Damping layers 11, 12 are provided in addition. Damping layer 11 acts between fuel injector 3 and cup 9, and damping layer 12 acts between fuel injector 4 and cup 10.
System 1 has a holding element 15, which connects fuel injector 3 to cup 9 of fuel distributor 2. Holding element 15 is configured as a retaining clip 15. Holding element 15 has a supporting surface 16, on which damping layer 11 is disposed. In addition, cup 9 has a collar 17 provided with shaped tabs 18, 19. In addition, a contact surface 21 is provided at an underside 20 of cup 9. In this exemplary embodiment, contact surface 21 is formed by underside 20 of cup 9. Other types of designs are possible as well, however. For example, underside 20 is not necessarily planar, and contact surface 21 may in part be formed by underside 20 of cup 9.
Holding element 15 has holding sections 22, 23, which are configured as U-shaped holding sections 22, 23 in this exemplary embodiment.
When assembled, collar 17 is inserted in holding element 15. In the assembled state, holding section 22 grips tab 18 of collar 17 from behind. In addition, holding section 22 grips tab 19 of collar 17 from behind in the installed state. This produces a keyed connection between cup 9 and holding element 15 along a longitudinal axis 24. Damping layer 11 is situated between contact surface 21 of cup 9 and supporting surface 16 of holding element 15.
Fuel injector 3 includes a collar 25, which may be formed by a connection sleeve 25. In the assembled state, collar 25 of fuel injector 3 is braced on supporting surface 16 of holding element 15 by damping layer 11. A fuel nipple 26 of fuel injector 3 is then situated within cup 9. A sealing ring 27 (
The presence of damping layer 11 enables an acoustic decoupling. Damping layer 11 may be produced from a visco-elastic material that allows a decoupling or an isolation of the noise sources produced at fuel injector 3 with respect to fuel distributor 2. In addition, fewer structure-borne noise components are transmitted from fuel distributor 2 to the add-on structure, especially cylinder head 7. As a result of these two effects, the sound radiation and the sound transmission from system 1 to the engine are reduced.
The mechanical operating principle for reducing vibrations with the aid of damping layer 11 and, correspondingly, damping layer 12 may be described as follows: While under an operational load, damping layer 11 is dynamically stressed to a high degree, and a high portion of vibrational energy is thereby dissipated by material damping of the elastomer. The dissipation of structure-borne noise always leads to damping of oscillation forms of fuel injector 3 and fuel distributor 2. As a consequence, a reduction in all structure-borne noise components that are transmitted by damping layer 11 from fuel injector 3 into fuel distributor 2 comes about. This characteristic corresponds to a decoupling, or rather an insulation, between fuel injector 3 and fuel distributor 2. Pure metal contacts, via which a transmission of structure-borne noise would efficiently be possible, are reduced or even prevented entirely. In particular, a design is possible in which the contacts are established only via plastic components.
The properties of damping layer 11, such as the thickness or form, an area proportion or material-specific properties may be adapted with regard to some optimization parameters. Optimization parameters above all are frequency contents to be damped, and the temperature.
This applies analogously to damping layer 12 and, as the case may be, additional damping layers that allow damping between fuel injectors 3, 4 and fuel distributor 2.
The development described on the basis of
Holding element 15 may be produced from formed sheet metal, for example. In this case, damping layer 11 is able to be configured as a separate insertion part 11 and rest against supporting surface 16 of holding element 15. Damping layer 11 may be very thin in this case. Conceivable is also a development in which damping layer 11 is connected to supporting surface 16 of holding element 15. Especially a connection with the aid of vulcanization is possible in this context. Damping layer 11 is produced from a rubber material in such a case. The term rubber should be taken quite generally in this case, and besides natural rubber also includes synthetic rubber materials.
In the first exemplary embodiment described with the aid of
In addition, another damping layer 31 is provided, which is situated between holding section 22 and tab 18 of collar 17. By way of additional damping layer 31, holding section 22 of holding element 15 is braced on collar 17 of cup 9. In a corresponding manner, another damping layer 32 is disposed also between holding section 23 and tab 19 of collar 17. Holding section 23 therefore supports itself on collar 17 of cup 9 by additional damping layer 32 as well. Damping layers 11, 31, 32 are thus provided on both sides of collar 17, so to speak. Damping layers 11, 31, 32 allow an especially advantageous damping of the vibrations that may be transmitted via the mechanical connection between fuel injector 3 and fuel distributor 2. Additional damping layers 31, 32 may be similar to damping layer 11 in their design. A development made of different materials may also be used for this purpose.
In the exemplary embodiments described with the aid of
Depending on the development, several advantages are therefore able to be derived from one or more damping layer(s) 11, 31, 32. Because of the decoupling, the transmission of structure-borne noise into fuel distributor 2, and thus into the add-on structure, especially cylinder head 7, is able to be improved while the requirements with regard to function and robustness are satisfied at the same time. Noise emissions from fuel distributor 2 are reduced as a result.
Despite damping layers 11, 31, 32, a relatively stiff connection of fuel injector 3 to fuel distributor 2 is able to be ensured. The flexibility of fuel injector 3, and similarly of fuel injector 4, increases only slightly and satisfies all of the functional requirements, e.g., low relative movement of fuel injectors 3, 4, and the strength requirements, especially with regard to wear of sealing ring 27. Acoustical, functional and strength requirements resulting from the design of fuel injectors 3, 4 and fuel distributor 2 may therefore be satisfied at the same time.
One potential development of holding element 15, which is made from reformed sheet metal, makes it possible to adapt radii and contours with regard to associated cup 9 and fuel injector 3 in order to avoid line contacts.
On account of the gimbal-type bearing arrangement of fuel injectors 3, 4, the full tolerance adjustment can be retained.
Since damping layers 11, 31, 32 are situated within holding element 15, so to speak, they are advantageously protected from the environment. Vulcanization may be used for an especially satisfactory protection from abrasion.
Moreover, the installation expense is kept low because of the low number of components. In addition, a compact design results as well, in which damping layers 11, 31, 32 do not require a lot of installation space.
Moreover, the decoupling may be used in a line-bound design of fuel injector 2, in that damping layers 11, 31, 32, which serve as decoupling elements, are used at the joint between suspended fuel injector 3 and the function block, i.e., fuel distributor 2.
The present invention is not restricted to the exemplary embodiments described.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2012 208 039.2 | May 2012 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/056862 | 4/2/2013 | WO | 00 |
