| Title of Invention | VALVE, ESPECIALLY FUEL INJECTION VALVE |
|---|---|
| Abstract | A valve, preferably a fuel injection valve for internal combustion engines, comprises a housing (1) in which is arranged a movable valve element (5) whose surface has at least one section (7; 15) provided with a wear-reducing coating (40). The coated surface section (7; 15) is exposed during operation of the valve to repeated friction or impact stresses, a rounded edge (36; 38; 39) being formed inside and/or at the border of the coated partial surface (7; 15). |
| Full Text | Valve, especially fuel injection valve State of the Art of Technology The invention proceeds from a valve, as it is for example, displayed in the disclosure document DE 100 38 954 A1. Such a valve, designed preferably as fuel injection valve, has a housing, in which valve element is arranged such that it can be moved. The valve element has different part surfaces which are subjected to repeated slide-friction or stresses due to collusion during the operation of the valve. At least a few of these partial surfaces are provided with a wear and tear mitigating coating, which minimizes the wear and tear that could occur through the slide-friction or stresses due to pollution, and thus improves the durability of the fuel injection valve. Further investigations of these partial surfaces have resulted in a situation that this coating could suffer detachment. The detachment of the coating begins ideally there where at the edge of the coated partial surface or within the coated partial surface a sharp edge is formed. The detachment process of the coating once begun continues its course during the longevity of the valve till the wear and tear mitigating effect is significantly affected, what then could lead to the considerable reduction of the durability of the valve. From the state-of-the-art of technology, different coatings of valves are known especially of fuel injection valves. The Patent Document DE 101 33 433 shows coatings, especially even diamond-type coatings, both of the valve element as well as surfaces in the housings working in conjunction with the valve element, that is the valve seating. Also from the document WO 01/61182 an injection valve is known in which the valve element has a coating which acts to mitigate the wear and tear. The coatings include here the entire surface of the valve element including the valve sealing surface, which acts in conjunction with the valve seat. Advantages of the Invention The invention-based valve in contrast has the advantage that the durability as against a customarily coated valve element is extended, and that the coating on the corresponding partial surfaces of the valve element subjected to mechanical stresses remains in tact over the entire life of the valve. For this purpose, edges which are designed within the coated partial surfaces are, at the edge of coated partial surfaces, have a rounded design. Because of this, the chipping/flaking of the coating in this area can be reliably prevented, which permits the coating to be stuck to the coated surfaces, with an overall reliability. Through the dependent claims, advantageous designs of the object of the invention are possible. In a first advantageous design, the coated partial surface is designed primarily as conical valve sealing surface, which acts together with a valve seating, which is provided in the housing. The valve element moves in its longitudinal direction, so that between the valve sealing surface and the valve seating a collusion stress occurs, if the fuel flow is directed through the longitudinal movement of the valve element to the injector openings. At the valve sealing surface, a snap ring groove is designed which on the transition to the valve sealing surface has a first and a second transition edge. These transition edges are advantageous designed with a rounding so that the wear and tear mitigating coating on the entire valve sealing surface, and especially in the area of the transition edges gets stuck extremely reliably. In a further advantageous design, the coated partial surface is designed as cylindrical guide segment, with which the valve element is guided in a corresponding bore in the housing. The edges, which restrict the guide segment of the valve elements are designed here similarly as rounded, in order to guarantee the adhesiveness of the wear and tear mitigating coating. The rounding of the edges happens preferably with a radius, which lies in the range of 10 urn to 250 urn. In this context, a range of 100 um to 150 urn is specially advantageous, particularly in the area of the valve sealing surface of a valve element. Further advantages and advantageous designs can be seen from the descriptions and drawings: Drawings: A design example of an invention-based valve is illustrated in the drawing. Drawings show: Figure 1 A section through a valve, which is illustrated here as a fuel injection valve and Figure 2 An enlarged illustration of the area identified with II of Figure 1 Description of the Design Examples In figure 1, an invention-based valve, which is designed here as a fuel injection valve, is illustrated in longitudinal section. The valve has a housing 1, in which the bore 3 is incorporated. The bore 3 is restricted on its combustion chamber side end by a primarily conical valve seating 9, from which several injections openings 11 emerge, which in assembly position of the valve converge in a combustion chamber of the corresponding IC Engine. In bore 3, a piston-shaped valve element 5 is provided, which has a guide-segment 15, with which the valve element 5 is guided in a corresponding bore segment 23 of the bore 3. The valve element 5 narrows itself starting from the guide segment 15, under build-up of a.pressure shoulder 13, and merges in a shaft area 25, which extends itself to a largely conical valve sealing surface 7. The valve sealing surface 7 forms a partial surface of the valve element 5, with which the valve element 5 together with the conical valve seating 9 works in conjunction. At the height of the pressure shoulder 13, the bore 3 is radially extended so that a pressure chamber/room 19 is created which while surrounding the valve element 5 continues up to the valve seating 9. A inlet channel 27, running in the housing 1, through which the combustion chamber 29 can be filled with fuel under great pressure, converges In the radial extension of the combustion chamber 19. The valve element 5 is impinged at its end opposite the valve seating by a closing force/power, which can be generated hydraulically or through a spring element; the corresponding devices are not illustrated in the drawing. If fuel is fed in the combustion chamber 19 under pressure, then a hydraulic force develops on the pressure shoulder 13 and on parts of the valve sealing surface 7, as a result of which an axial opening surface is exercised on the valve element 5, which is directed away from the valve seating 9 and thus the closing force. Depending upon the behaviour of the closing force and the hydraulic opening force the valve element 5 moves itself away from the valve seating 9 and opens up the injection openings 11, or it moves itself to the valve seating 9 and closes thereby the injection openings 11 against the combustion chamber 19. Whether the control takes places finally through the closing force or through an alternating pressure in combustion chamber 19 depends on the type of the valve. Valves of this type preferably come to be applied in self-igniting combustion engines. In figure 2, the section identified with II of figure 1 is illustrated in enlargement. The valve sealing surface 7 has a first conical surface 32 and a second conical surface 34 which are separated through a snap ring groove 30, where the snap ring groove 30 has a width of "d". At the transition of the first conical surface 32 to snap ring groove 30, a first transition edge 36 is formed, and at the transition of the snap ring groove 30 to the second conical surface 32 a second transition edge 38 is formed. The opening angle of the first conical surface 32 in this context is smaller than the opening angle of the conical valve seating 9, while the opening angle of the second conical surface 34 is larger than that of the valve seating 9. Through this design of the conical surface 32, 34 the valve element 5 comes to its seating on the valve seating 9 in its closing position with the first transition edge 36. The first transition edge 36 thus forms a sealing edge, on which a very great degree of surface pressure prevails, so that the injection opening 11 are securely sealed even under high pressure in the combustion chamber 19. The valve sealing surface 7 is equipped with a coating 40, which has a wear and tear mitigating effect, and which is for instance designed as a diamond-type coating, that is a so called diamond-like-carbon-coating (VLC Coating). In figure 2, the valve element 5 is illustrated in the left half, partially cut, so that the coating 40 is visible. The coating 40 shown here is significantly highlighted for purpose of clarity. The thickness is generally a fraction of one up to a few micrometers. The first transition edge 26 and second transition edge 38 are respectively designed rounded, for example with a radius R, as it is indicated in figure 2. The rounding radius are in this case is in the range of 10 urn to 250 urn, preferably in the range of 100 urn to 150 urn. The width d of the snap ring groove 30 in this case is preferably in the range of about 500 um so that a softer, consistent transition from the first conical surface 32 to the snap ring groove 30 and from this to the second conical surface 34 is obtained. It can also be visualized that a third transition edge 39, formed at the transition of the first conical surface 32 to the shaft area 25 of the valve element 5, is similarly rounded with a radius R. However, even a different rounding is possible which does not precisely correspond to a circular segment with radius R, but has a different form in cross section; in any case it is important that a sharp edge must be avoided. Similarly it is also possible to bring a wear and tear mitigating coating 40 on the partial surface of the valve element 5, forming the guide segment 15, for minimizing the friction between the guide segment 15 of the valve element 5 and the bore segment 23. Even here a rounding radius R is proposed at the transition of the guide segment 15 to the pressure shoulder 13, so that the coating 40 in this area does not get detached. It is also possible to equip the valve element 5 over its entire surface with a wear and tear mitigation coating 40, as it can be found to be more advantageous from the point of view of process technology to equip the entire valve element 5 with a DLC-Coat and not only a partial segment thereof. The rounding radius R or the other rounding form need not necessarily be the same at all edges. It is also possible to visualize different rounding radii which are matched to the respective peculiarities. Besides the coating of a valve element 5, which in this case has the form of a piston-shaped valve pin, the coating can also be brought on any other moving component of a valve, where even here the edges must be corresponding rounded. Claims: 1. Valve, preferably fuel injection valve for the internal combustion engine, with a housing 1, with a movable valve element 5 arranged therein, the upper surface of which has at least one partial surface (7; 15) equipped with a wear and tear mitigating coating (40) where the coated partial surface (7:15) is subjected to repeated friction-collusion-related stresses during operation of the valve is thereby characterized that within and/or at the edge of the coated partial surface 7; 15 an edge 36, 38, 39 is formed designed with a rounding. 2. Valve according to claim 1 is thereby characterized that the coated partial surface 7; 15 is designed primarily as conical valve sealing surface 7, which is formed at one end of the valve element 5 facing the valve seating 9, where the valve element 5 acts together with the valve seating 9 and the valve sealing surface 7 is equipped with the wear and tear mitigating coating 40. 3. Valve according to claim 2 is thereby characterized that in the valve sealing surface 7, a snap ring groove 30 is formed which has at he transition to the valve sealing surface 7 a first transition edge 36 and a second transition edge 38, where the transition edges 36,38 are designed with a rounding. 4. Valve according to claim 1 is thereby characterized that the coated partial surface 7; 15 of the valve element 5 is designed as cylindrical guide segment 15, with which the valve element 5 is led in a corresponding bore 3 in housing 1. 5. Valve according to one of the claims 1 to 4 is thereby characterized that the rounding is done with a rounding radius R, which lies in the range of 10 urn to 250 urn. 6. Valve according to claim 5 is thereby characterized that the rounding radius R is in the range of 100 um to 150 urn. 7. Valve according to one of the claims 1 to 4 is thereby characterized that the coating 40 is made of a carbon containing, diamond type coating (diamond like carbon, DLC). Dated this 2 day of November 2007 (ARINDAM PAUL) Of De PENNING & De PENNING AGENT FOR THE APPLICANTS |
|---|
| Patent Number | 272400 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Indian Patent Application Number | 4939/CHENP/2007 | |||||||||
| PG Journal Number | 14/2016 | |||||||||
| Publication Date | 01-Apr-2016 | |||||||||
| Grant Date | 31-Mar-2016 | |||||||||
| Date of Filing | 02-Nov-2007 | |||||||||
| Name of Patentee | ROBERT BOSCH GMBH | |||||||||
| Applicant Address | POSTFACH 30 02 20 D-70442 STUTTGART | |||||||||
Inventors:
|
||||||||||
| PCT International Classification Number | F02M 61/16 | |||||||||
| PCT International Application Number | PCT/EP06/60959 | |||||||||
| PCT International Filing date | 2006-03-22 | |||||||||
PCT Conventions:
|
||||||||||