Electrically controlled fuel injection pump for internal combust

Details Electrically controlled fuel injection pump for internal combust Electrically controlled fuel injection pump for internal combust

1991-08-28

1995-04-04

Kashnikow, Andres

Fluid sprinkling, spraying, and diffusing

Unitary injection nozzle and pump or accumulator plunger

239600, F02M 3900

Patent

active

054029449

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to am electrically controlled fuel injection pump for internal combustion engines. In fuel injection devices of this kind, a pump piston, preferably driven by the engine camshaft, is disposed together with an associated injection nozzle in a common housing. The fuel injection quantity is controlled during the pump piston compression stroke by a quantity control valve, which for space reasons is secured to a laterally projecting housing part.
From a supply tank, fuel is pumped by a feed pump in a low-pressure chamber that communicates with the pump work chamber via a metering line. During the pump piston intake stroke, fuel flows at low pressure via the metering line into the pump work chamber, and during the compression stroke the fuel flows back again into the low-pressure chamber as long as this metering line is open. The quantity control valve is disposed in this metering line, so that in the blocked state, the pressure necessary for injections can build up in the pump work chamber.
Because of the high operating pressures of such fuel injection pumps, a particularly rigid connection between the quantity control value and the pump housing is necessary. In a known fuel injection pump of this generic type (U.S. Pat. No. 4,653,455), the quantity control valve is therefore secured to the projecting housing part, which has an external thread, with a union nut. This arrangement has the disadvantage, however, that providing an external thread on the pump housing is expensive, since in view of the high injection pressures the pump housing is of tempered steel. Another disadvantage is that with such an arrangement it is not possible to carry the metering line in a straight line from the pump work chamber to the quantity control valve; it is instead necessary to embody this portion of the metering line as a high-pressure bore bent twice at right angles. However, a metering line embodied in this way is unfavorable from a hydraulic standpoint, and rounding of the bends is difficult. Additionally, the problem arises of sealing off the bores from the outside in the high-pressure region.


ADVANTAGES OF THE INVENTION

The fuel injection pump according to the invention has the advantage over the prior art that no screw thread needs to be provided on the pumps housing for connecting the quantity control valve in a high-pressure-proof manner to the pump housing, and that the high-pressure segment of the metering line can be embodied as a rectilinear high-pressure bore that directly connects the pump work chamber to the quantity control valve. Instead of an expensively made external thread, the pump housing need merely be provided with lateral recesses, which for high-pressure-proof fastening of the quantity control valve to the pump housing are engaged in a forked manner by the fastening cuff, which is provided with an internal thread. Because of the absence of the external thread on the projecting housing part of the pump housing, it is possible to embody this housing part in such a way that there is sufficient room to receive the metering line in a direct connecting line between the quantity control valve and the pump work chamber. For this purpose, the fastening cuff is pushed onto the projecting housing part from the side remote from the pump piston, so that the side of the projecting housing part toward the pump piston is not covered by the fastening cuff, and the only constraint on its embodiment is the requirements of pressure conduit routing to the pump work chamber.
In an advantageous embodiment of the invention, the lateral recesses are embodied by two transverse grooves extending at right angles to the direction of reciprocation of the pump piston. The fastening cuff has a corresponding inner collar on its fork-like part, and is simply pushed from the side remote from the pump piston onto the projecting housing part. By tightening the screw sleeve, the quantity control valve is pressed against a sealing face provided on the projecting housing part, and the fast

REFERENCES:
patent: 293734 (1884-02-01), Harrison
patent: 2036087 (1936-03-01), Chapman
patent: 3157407 (1964-11-01), Aulabaugh
patent: 4474159 (1984-10-01), Katnik
patent: 4474160 (1984-10-01), Gartner
patent: 4475516 (1984-10-01), Atkins et al.

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