Patent Application
20090256357
The present invention relates to a method according to the preamble of claim 1.
The invention also relates to a sealing joint according to claim 7.
Diesel engines are equipped with fuel injectors for injection of fuel to the cylinders. The fuel injectors are in flow communication with a common rail or distribution pipe which collects the fuel under high pressure from the fuel pump. During operation of the engine each injector will be supplied with fuel at the same pressure from the common rail or distribution pipe. For this purpose the common rail is provided with one or more fuel outlets, which lead to a respective fuel injector and one or more fuel inlets from the fuel pump.
A method of manufacturing such common rails or fuel distribution pipes is by extruding aluminum. According to this method, heated aluminum is pressed through a die whereby long profiles of uniform cross sectional form, either with a solid profile or a hollow profile, as is the case in the manufacture of a tube. The length of the extruded profile is usually standardized, and they are then cut to the desired length depending on the application. In the above mentioned case with an extruded common rail or fuel distribution pipe, i.e. en elongated body with a hollow profile, the ends of the common rail will be completely open. As long as the openings are not to have a function, for example by connecting to a return conduit or the like, they need to be sealed.
One method of sealing an opening is with the aid of a sealing plug. Since the common rail or distribution pipe will be subjected to high inner pressure it is important that the sealing plug be securely fixed in the opening so that it will not loosen during engine operation.
For this purpose, the sealing plug can be provided with external threads for engagement with corresponding internal threads in the opening. Another method is to force fit the sealing plug in the opening or to weld the sealing plug in the opening (see for example U.S. Pat. No. 3,872,891 and US 2003/0188715 A1).
A disadvantage with these methods of fixation is that they are expensive and/or time consuming (for example the solution with threads requires additional processing with the aid of a threading die and the required wall thickness) force fitting requires exact tolerances in manufacturing both the pipe and the sealing plug, and welding requires welding equipment adapted to aluminum.
One purpose of the present invention is thus to provide a method of sealing a common rail or fuel distribution pipe which can be performed in a simple and inexpensive manner.
This purpose is achieved in the present invention with a method with the characteristics decided in the characterizing clause of claim 1.
The purpose is also achieved with a joint with the characterizing features recited in the characterizing clause of claim 7.
A sealing plug is inserted in the opening and positioned so far into the channel that when a stamping tool with a outer diameter which is somewhat larger than the inner diameter of the opening is applied perpendicularly to the end surface and concentric with the opening, the part of the end surface which constitutes the periphery of the opening is deformed plastically and is pressed into the channel to form an abutment outside the sealing plug and with an inner diameter which is less than the outer diameter of the sealing plug. This provides a number of advantages. Firstly, the sealing plug will be locked into the channel in the axial direction against movement out of the opening when there is overpressure in the channel, which secures that it will be held in place. Secondly, the abutment formed by the stamping will in itself constitute a seal since the portion of the material which is pressed down during the stamping is wedged particularly between the sealing plug and the inner walls of the channel. Furthermore a fuel distribution pipe does not need to be premachined in any manner, i.e. by providing the inner surface of the channel with threads, and it does not need to have the same tolerances as for force fitting as regards the diameters of the opening and the sealing plug. Consequently, the above fixation method for the sealing plug achieves a simple and inexpensive method of sealing a tubular body.
Preferably a support is arranged inside the channel to function as an abutment for the sealing plug when it is positioned in the channel. This secures correct positioning depth for the sealing plug in the channel.
The portion of the periphery of the opening which is deformed is suitably the portion which the stamping tool overlaps, and more suitably the inner diameter of the opening is 19 mm and the outer diameter of the stamping tool is 20 mm.
Preferably, the tubular body is made by extrusion of aluminum, and more preferably the tubular body is a fuel distribution pipe intended for an internal combustion engine. The extrusion itself entails a need for end sealing, when the extruded material is pressed through a die and leaves open ends. Aluminum is a material easily malleable for the purpose which is suitable for this type of method.
The sealing plug is suitable made of copper. This is a soft material which can be deformed somewhat when the opening is deformed plastically and is pressed into the channel to form the shoulder.
Preferably, the sealing plug is provided with a gasket for a sealing against the surrounding walls of the outer channel section. The sealing effect can thus be improved.
The present invention will be described with reference to the accompanying drawings, in which:
When sealing the fuel distribution pipe 1, the sealing plug 15 is inserted in the opening 7 and is positioned in the outer channel section 9 so that it abut against the support 13. According to
The fuel distribution pipe 1 is then placed in a clamp or corresponding fixing means so that it is held securely. The stamping tool 19 is positioned above the opening 7 so that the cross section of the stamping tool is concentric with the cross section of the opening. During this time the sealing plug 15 is in place in the outer channel section in abutment against the support 13.
During the stamping process itself, the stamping tool moves perpendicularly to the end surface 5. The stamping tool 19 will strike a portion of the surrounding periphery of the opening 7, corresponding to the difference in diameter between the stamping tool 19 and the opening 7. Since the fuel distribution pipe 1 is firmly fixed during the stamping and during the continued movement downward of the stamping tool, the material of the pipe 1 will be deformed, i.e. the channel wall will be deformed plasticly and the surrounding periphery of the opening will be pressed or upset down into the outer channel section 9. After a completed impact, i.e. somewhat above the upper surface of the sealing plug 15, the stamping tool 19 is removed. It is evident from
Suitably the fuel distribution pipe 1 is made of aluminum, since the pipe as such is preferably extruded and it is simple to deform it plastically in the subsequent stamping step, but other malleable metals are possible.
It is also conceivable that the stamping tool has a solid circular cross section and not a circular annular cross section as described above. I de latter case it is possible to use sealing plugs with a central portion which extends out of the opening after its positioning against the support in the outer channel section, for example a coupling threaded into the sealing plug or the like as long as this portion can be held within the annular shape of the stamping tool and will not be affected by the stamping blow. If there is no portion of the sealing plug which is outside the opening of the outer channel section or the sealing plug is sufficiently far into the outer channel section it is possible to use a stamping tool with a solid circular cross section.
Other applications than a fuel distribution pipe are conceivable, for example a fuel heating housing for an internal combustion engine or other extruded tubular bodies which need end sealing.
It is also conceivable to use other malleable materials than copper in the sealing plug.
The invention also relates to a sealing joint for sealing an opening in a tubular body 1, which comprises at least one channel 3 extending in a longitudinal direction of the body, in which an opening 7 to the channel is formed in the respective end surface of the body. The joint comprises a sealing plug 15 positioned in the channel 3, and a shoulder 21 with an inner diameter which is less than the outer diameter of the sealing plug 15, the shoulder 21 being formed in the channel 3 outside the sealing plug 15 by the portion of the end surface 5 constituting the periphery of the opening 7 being deformed plastically and pressed into the channel 3 to form the shoulder.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0800837-7 | Apr 2008 | SE | national |
