Internal-combustion engines – Combustion chamber means having fuel injection only – Combination igniting means and injector
Patent
1988-01-07
1989-05-30
Dolinar, Andrew M.
Internal-combustion engines
Combustion chamber means having fuel injection only
Combination igniting means and injector
123298, 123549, 239133, F02M 3112
Patent
active
048340430
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a fuel injection nozzle. Injection nozzles of the kind under discussion can be assembled easily, because the glow element together with the sleeve and the contact element, as a pre-fabricated structural unit, can be inserted into the clamping nut from its open end and pushed as far as the support shoulder. In the known injection nozzles of this generic type (German Patent Application 35 02 109.8), the glow element is embodied by a wire coil, which is supported and electrically contacted on the sleeve on its end remote from the contact element. This embodiment dictates a sleeve having internal protrusions, which make manufacture more difficult and also hinder the flow of the air aspirated by injector action.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a fuel injection nozzle which has the advantage over the prior art that the aspirated air can flow substantially unhindered from the combustion chamber into the annular space formed between the sleeve and the glow element, and that the sleeve does not have to have any internal protrusions. The jacket heating conductor provided for forming the glow element is a time-tested structural element which is capable of producing high electrical heating outputs.
Assembling the glow attachment comprising the glow element, sleeve and contact element is simplified still further if the outer annular jacket of the jacket heating conductor is electrically contacted with the end remote from the contact element of the inner resistance wire and is soldered to the sleeve at at least one point.
The sharp bending of the end portion of the jacket heating conductor connected to the contact element toward the associated end region of the coil is avoided if this end region is disposed at the side of the combustion chamber and the coil extends counter to the flow direction of the fuel toward the nozzle body.
It is particularly advantageous if the end portion oriented toward the contact element of the jacket heating conductor is embodied as a so-called cold end, which presents a lesser electrical resistance to the heating current than the remaining portion of the jacket heating conductor.
As a result, the sleeve, the connection end of the jacket heating conductor and in particular the sealing provided there, and the contact element are subject to less thermal stress than when a jacket heating conductor lacking a cold end is used.
One possible way to attain a cold end of the jacket heating conductor is to use in that region of the jacket heating conductor, a material, such as copper, that has a lesser electrical resistance than that in the remaining region, and to provide the shortest possible transition zone, that is, the junction between the copper and the heating conductor.
Another preferred possibility is to produce dissimilar cross-sectional faces of the annular jacket and of the inner resistance wire, in particular by hammering or drawing the corresponding part of the jacket heating conductor prior to the winding. In the final analysis, this results in a thickened end portion as compared with an embodiment lacking a cold end, the greater surface area of which is likewise effective in providing a thermal relief of the jacket heating conductor sealing and of the contact element.
If a sleeve disposed between the nozzle body and the clamping nut is provided for conducting current, the contact element, given the above-described provisions for reducing the thermal load, can also be formed directly by a thickened or inwardly extended rim of the sleeve.
The assembly of the injection nozzle is simplified if the jacket heating conductor, the sleeve that carries and electrically contacts it, a ceramic insulting body resting on its upper face end and the contact element are pre-fabricated into an insertion unit by soldering or gluing.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its
REFERENCES:
patent: 1641421 (1927-09-01), French
patent: 2130365 (1938-09-01), Paulson
patent: 4572146 (1986-02-01), Grunwald et al.
Kaczynski Bernhard
Schmitt Alfred
Dolinar Andrew M.
Robert & Bosch GmbH
Striker Michael J.
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