Robert Boschgmbh

Helmut Pfeifle

Jean Leblanc

Jean Pigeroulet

Max Straubel

Reinhard Schwartz

Dominique Buisson

Francois Henry

Helmut Laufer

Walter Hafele

Dietrich Trachte

Francois Rossignol

Walter Egler

Eberhard Hofmann

Helmut Tschoeke

A fuel injection device having a pump piston which during the supply stroke pumps fuel from a pump work chamber into an injection line which leads to a fuel injection valve. Directly adjacent to the branching off of the injection line from the pump work chamber, at the diameter of the injection line, a valve seat is provided, at which the injection line then merges with a chamber into which a pressure valve closing member plunges. The valve closing member is tightly guided in a guide bore, loaded by a valve spring, and in the chamber has a pressure shoulder adjoining the sealing surface that cooperates with the valve seat. The rear side of the pressure valve closing member communicates with a continuously open relief line. Because of this construction, the pressure valve closing member operates as an equal-pressure valve and simultaneously as a deflecting piston as well, with the aid of which a pressure rise in the pump work chamber is built up in a retarded manner until such time as the pressure valve closing member comes to rest on a stop. A pressure rise of this type is particularly advantageous in connection with control of the injection phase by means of a magnetic valve subjected to the high pressure.

Fuel injection device

A fuel injection apparatus which the termination of the effective pump supply stroke is effected by exposing a relief conduit with the aid of a valve having for instance a control edge, whereupon a highly pressurized fuel flows out via the relief conduit and is directed into a pressure chamber defined by a rear face of a pressure valve closing member. The pressure valve closing member is located in a connection with a fuel injection line that leads from the pump work chamber to the fuel injection valve and is acted upon by a valve spring to effect closing of this injection line. The impact of fuel that reaches the pressure chamber via the releif conduit reinforces a fast closure of the pressure valve closing member at the end of injection, which leads to an abrupt termination of an injection cycle. In addition, or altenatively, the fuel injection valve closing member can also be acted upon by the impact of fuel diversion.

Fuel injection apparatus for internal combustion engines

A fuel injection apparatus for definite pilot and main injection in internal combustion engines. A hydraulic auxiliary pump is supplied via a pressure line with fuel from a high-pressure injection pump, which fuel reaches a main injection nozzle and simultaneously drives the hydraulic auxiliary pump. The hydraulic auxiliary pump contains a differential piston comprising a reservoir piston and a pilot injection piston with different diameters and with a spring prestressing such that between the end of supply of the pilot injection and the onset of supply of the main injection, an injection-free spacing stroke (DH) which can be predetermined by means of mechanical stops results, during which spacing stroke (DH) the reservoir piston by retracting further, receives the supply quantity which is pumped during the injection interval by the high-pressure injection pump.

Fuel injection apparatus for definite pilot injection and main injection

A fuel injection pump for internal combustion engines, in which beyond a predetermined remnant stroke during the supply stroke of the pump piston a relief conduit is opened via a first control edge and the remaining fuel pumped by the pump piston is pumped into a reservoir connected there. During the subsequent intake stroke, the diverted fuel is pumped back into the pump work chamber of the pump piston, until the first control edge again closes the relief conduit. During the subsequent intake stroke of the pump piston, in particular at the bottom dead center position of the pump piston, the relief conduit to the reservoir is once again opened by a second control edge, and then a complete relief of the reservoir is attained. It is during this phase that the metering of the fuel to be injected during the next supply stroke of the pump piston also takes place, via a magnetic valve. With an apparatus of this kind, it is advantageous that the fuel quantity per supply stroke of the pump piston that is actually to be injected can be metered exactly by means of a magnetic valve under pressure conditions that remain constant despite variable opening times.

Fuel injection pump for internal combustion engines

The fuel injection quantity of a fuel injection apparatus provided with a fuel injection pump is electrically regulated by means of the opening duration of a metering valve. Additionally, a shift in the instant of supply onset controlled in accordance with operating characteristics is attained by means of a change in the return-flow fuel quantity, which is diverted into a refill reservoir and then refilled completely into the pump work chamber by the beginning of the next subsequent injection stroke. Serving as the sole connection between the refill reservoir and a pump work chamber is an overflow conduit, the overflow opening of which, located at the discharge location into the pump work chamber, is opened by two control locations on the pump piston at the end of supply and once again shortly before bottom dead center. The two control locations are embodied by an oblique control edge on the pump piston that determines the end of supply and by a horizontal, end-face control edge, with the horizontal control edge assuring that shortly before bottom dead center any remnant quantity of the return-flow fuel still remaining in the refill reservoir is refilled back into the pump work chamber.

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Stuttgart, Germany

Helmut Pfeifle