Internal-combustion engines – Combustion chamber means having fuel injection only
Patent
1994-08-08
1996-02-27
Moulis, Thomas N.
Internal-combustion engines
Combustion chamber means having fuel injection only
239584, F02M 300, F02B 500
Patent
active
054940150
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a fuel injector assembly for the injection of fuel into a combustion chamber of an internal combustion engine and in particular to cylinder compression pressure actuated fuel injector assemblies.
Examples of pressure actuated fuel injector assemblies are shown in Patent Specification No's DE 661,468, DE 688,311, DE 708,739, FR 799,951, FR 849,154, U.S. Pat. No. 2,589,505, U.S. Pat. No. 2,602,702, U.S. Pat. No. 2,740,667 and U.S. 2,740,668. Such cylinder pressure fuel injector assemblies have considerable advantages particulary for 2-stroke engines. These are sometimes erroneously referred to as pumpless diesel injector units. Cheap, small displacement, internal-combustion engines working on the compression ignition principle have been much sought after for many years. Cost is a major factor in the almost total absence of the availability of small diesel engines except for specialised applications where cost is a secondary factor. Efforts to design and develop a low cost fuel injector assembly, which would be actuated by combustion chamber pressure has heretofore proved unsuccessful. The aforementioned patent specifications demonstrate quite clearly that this problem has been long appreciated and that the way forward was to combine together within the injector assembly unit itself the pumping function. Thus, the so called pumpless diesel injector unit. It is long recognised, as these patent specifications adequately demonstrate, that some form of pump could be provided which could be readily easily actuated in this manner. Unfortunately, all these fuel injector assemblies suffered from serious drawbacks. A primary drawback is that there was very often, if one was to get efficient combustion, a need to provide a secondary combustion chamber. In many cases the injection pressures were not sufficient to have the injection operation carried out at pressures equivalent to those of more conventional separate pump and injector units. These units as will be referred to again below also had a major disadvantage in respect of contamination by the combustion gases. There were other problems with priming and efficiency generally.
Many attempts were made to overcome the problems of injection pressure and general fuel atomisation.
This problem of injection pressure and atomisation was overcome many years ago by what was in effect a 2-stage lift injection process. When this solution to the problem, which was first disclosed in DE 688311, was achieved the remaining problems were such as to prevent the practical application of the 2-stage lift system from such fuel injector assemblies. The problems that had heretofore been minor, now become major and have prevented the application of pressure actuated fuel injector assemblies to small displacement internal combustion engines working on the compression ignition principle.
As stated, this invention is particularly concerned with the type of injector shown in DE 688,311, said injector assembly being of the type comprising an injector body and two-stage snap-action lift stepped piston mounted in a bore in the injector body having a gas passage at one end for communicating with an engine combustion cheer, the piston having a wider part slidable within the bore and a narrowed part extending through the gas passage and urged by a timing spring into engagement with a first internal sealing land for the gas passage to form a gas-tight seal until the pressure of combustion chamber gases acting on an outer portion of the narrowed part is sufficient to overcome spring pressure and move the piston for inlet of combustion chamber gases to act on the wider part of the piston whereby the piston snaps inwardly under the increased force acting against the spring due to the increase in exposed area acted on by the gases, valve means for sealing the gas passage when the piston is moved inwardly, a fuel pump mounted on the piston, the pump comprising a plunger for reciprocal pumping movement within a complementary fuel pump cylinder communicating with the bore to delive
REFERENCES:
patent: 2708601 (1955-05-01), Links
patent: 3801021 (1974-04-01), Jakob
patent: 4350301 (1982-09-01), Erwin et al.
patent: 4360163 (1982-11-01), Williams
patent: 5127584 (1992-07-01), Sczomak
patent: 5211145 (1993-05-01), Ichikawa et al.
Moulis Thomas N.
Rynhart Research and Development Company Limited
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