US 4,478,188 AGranted

Adjustable hydraulically operated stop

AssigneeRobert Bosch GmbH

InventorFranz Eheim

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Abstract

An adjustable hydraulically operated stop for pulsed loading is proposed, which is particularly applicable for the metering piston of a fuel injection system. The stroke of this metering piston can be varied by adjusting a stop body by means of a metering converter. The supply chamber communicating with a fuel source or with the pump work chamber of one of the pump/nozzles of the fuel injection system, whose size is dependent on the stroke of the metering piston, determines the injected fuel quantity. The adjustable hydraulically operated stop encompasses a mechanical stop body, which is movably supported with respect to its adjusting member embodied by a sheath and communicates therewith via fluid, which also surrounds the adjusting member. The adjusting forces for the adjusting member are kept small, and the holding forces required to prevent a change in the position assumed by the adjusting member are kept equal to zero, because pressure fluctuations affecting the fluid are cancelled out with respect to the adjusting member. To this end, the adjusting member is received in its entirety within a fluid-filled chamber. A spring acting upon the stop body assures the constant renewal of the hydraulic cushion in the case of pulsed operation.

Claims12

Dependent claims

An adjustable hydraulically operated stop comprising a housing for pulsed loading, in particular for a metering piston of a fuel metering apparatus, said metering apparatus provided with a supply chamber of said piston wherein said hydraulic stop encompasses a stop body which is movably supported in a distributor and arranged to determine the stroke length of the metering piston associated therewith, said stop body also being movably supported with respect to an adjusting member and subjected to a hydraulic fluid in which said hydraulic fluid also surrounds said adjusting member, such that pressure fluctuations acting upon the hydraulic fluid are cancelled out with respect to said adjusting member, whereby the position thereof is unaffected, said adjusting member for said stop body being a sheath provided with a sheath wall and a bore having a chamber-like enlargement, an opening in said sheath wall arranged to discharge into said bore, said sheath further being displaceably guided in an adjusting direction on a rod-like means attached to said housing and engaging said bore, said rod-like means arranged to protrude as far as said chamber-like enlargement, said sheath further arranged to cooperate with a stop body slidably arranged relative to said sheath whereby said stop body sealingly engages said sheath bore and protrudes into said chamber-like enlargement.

Dependencies are inferred from the claim text.