Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1993-04-14
1994-04-05
Cross, E. Rollins
Internal-combustion engines
Charge forming device
Fuel injection system
123468, F02M 5502, F02M 6114, F02M 6946
Patent
active
052995429
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
The invention is based on a fuel distributor for a fuel injection engine. A fuel distributor for an internal combustion engine is already known from DE 37 30 571 A1 which uses a plurality of fuel injection valves for the fuel supply. The number of valves, corresponding to the number of through valve acceptance features in a valve carrier. The valves are electromagnetically actuable fuel injection valves being axially insertable into the valve acceptance features, and has a supply conduit open towards the valve acceptance features.
The fuel injection valves are fixed on the valve carrier by means of a contract strip which passes over, in bonnet-shape, the part of the injection valves protruding from the valve acceptance feature and hooks by means of engagement lugs into corresponding engagement recesses in the valve carrier. The injection valves are fixed in the axial and peripheral directions by this contact strip, which acts simultaneously to provide the electrical contact for the injection valves.
Tolerance problems between electrical plug pins on the injection valve and electrical plug pin acceptance features in the contact strip can, however, cause certain rotations of the injection valves during assembly so that the injection valves do not maintain their specified direction in the valve acceptance features and, in consequence, their jet direction is altered in an undesired manner.
Furthermore, starting difficulties in the internal combustion engine can occur during a hot start of an internal combustion engine equipped with a fuel distributor of this type due to the formation of fuel vapour bubbles if, during the first few seconds after starting, fuel mixed with vapour bubbles is injected. The fuel vapour bubbles occur due to the strong thermal effect of the internal combustion engine, which has been heated in operation, on the devices carrying the fuel. The cause of the starting difficulties is the severe weakening of the fuel/air mixture formed and, therefore, an unwillingness to ignite.
ADVANTAGES OF THE INVENTION
The fuel distributor according to the invention has an advantage that the injection of fuel free from vapour bubbles by the fuel injection valves is ensured, even in the first few seconds after a hot start of the internal combustion engine, by the formation of an adequate reservoir with fuel free from vapour bubbles. The fuel/air mixture formed in this way has good ignitability.
In the case of a fuel distributor consisting of a single flow passage, good cooling is achieved by fuel flow on all sides around the valve acceptance feature and the formation of vapour bubbles is avoided. The fuel volume free from vapour bubbles within the valve acceptance feature must be protected from mixing with fuel mixed with vapour bubbles. This is achieved by an arrangement of at least one fuel supply opening on a side of the valve acceptance feature which is not directed against the flow direction, for example one at right angles to the flow direction or facing away from the flow direction.
The fuel distributor according to the invention has one advantage that it can be manufactured in a simple and low-cost manner and permits a large fuel volume free from vapour bubbles. Furthermore, the fuel located in the outer annular gap is cooled by the fuel flowing through the fuel supply passage so that vapour bubble formation is prevented in the outer annular gap.
Advantageous further developments and improvements to the fuel distributor are possible by means of the measures listed hereinafter. It is advantageous to fasten the fuel injection valve on the valve acceptance feature of the fuel distributor by means of a clip, which represents a particularly low-cost fastening. Fastening the fuel injection valve on the fuel distributor by means of a bayonet fastening permits rapid assembly and fixing in an accurately specified rotational position.
DRAWING
Embodiment examples of the invention are shown simplified in the drawing and are explained in more detail in the following description.
FIG. 1
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Cross E. Rollins
Greigg Edwin E.
Greigg Ronald E.
Moulis Thomas
Robert & Bosch GmbH
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