Pumps – Expansible chamber type – Pumping member position controlled port
Patent
1986-11-24
1988-10-18
Freeh, William L.
Pumps
Expansible chamber type
Pumping member position controlled port
123502, 417289, F04B 706, F02M 3704
Patent
active
047783583
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is based on a fuel injection pump in accordance with the type of the main claim.
In a known fuel injection pump of this type (Bosch distributor injection pump VE Bosch technical instruction VDT-u 2/2 De) the injection adjustment bolt is secured against axial displacement by a pin which transversely penetrates the injection adjustment piston immersing into a bore of the drive ring, whereby the pin is protected against dropping out by means of a steel clamp which encompasses the injection adjustment piston.
This known type of axial securing of the injection adjustment piston is disadvantageous in that after inserting the bolt during assembly of the injection pump one must mount the safety pin and the clamp requiring two operating steps, whereby the injection adjustment piston must be brought into the turning position in which the bore receiving the safety pin is in a superimposed position with the associated bore in the drive ring. Moreover, each additional operating step or each additional structural part, like the safety pin and the sheet metal clamp, disadvantageously require an additional manufacturing control irrespective of the additional material and finishing expenses for these parts. Since such fuel injection pumps are made in great numbers, the aforementioned disadvantages are accordingly serious.
A substantial disadvantage of this known fixing of the injection adjustment bolt consists in that the injection adjustment bolt is prevented from rotating around its own axis because of the safety pin. Thereby, engagement faces develop one sided wear with respect to the drive ring and with respect to the injection adjustment piston due to the stress. Thus, when running, wear deviations result from the actual value to the rated value of the start of the feeding, which may result in a critical running or even a damaging of the internal combustion engine which is supplied by the injection pump.
SUMMARY OF THE INVENTION
In contrast thereto, the fuel injection pump in accordance with the invention and the characterizing features of the main claim is advantageous in that the injection adjustment bolt is secured in view of its position against an axial displacement after being assembled, so that no additional safety elements or finishing operations are required. In addition so material saving and very simplified assembly, additional possible error sources are also eliminated and the operating or finishing control is simplified. Since the injection adjustment piston can rotate around its axis, a substantially uniform wear is performed and thereby an increase in the control precision of this feeding start device.
This invention is preferably usable in distributor injection pumps. Therein either the pump pistons are driven radially with respect to the distributor, shaft by means of a drive ring in the form of a cam ring, or wherein only a single pump piston is provided which is actuated into a reciprocating movement by means of a cam disk which runs on rollers and which is simultaneously rotated by a drive shaft.
In accordance with an advantageous embodiment of the invention, a corresponding ring segment of the jacket face of the rotating part is used as a support face in the direction of the axis of the drive ring. The fuel injection pump may be provided with a rotating pump piston as a distributor and a dog clutch between the pump piston and a rotating drive shaft. This ring face is provided at the end segment of the drive shaft facing the pump piston. Since the rotating part is hardened in the area of the ring segment and since the complete cam drive is immersed in Diesel oil, a very simple, effective and wear resistant securing is obtained in one of his axial direction for the injection adjustment bolts.
As a securing in the opposite direction a plurality of variants are possible in accordance with the invention. A rotatably guided slide ring is mounted in a transverse opening of the injection adjustment piston which is provided with a transverse bore for receiving
REFERENCES:
patent: 4168690 (1979-09-01), Hofer
patent: 4262645 (1981-04-01), Kobayashi
Freeh William L.
Robert & Bosch GmbH
Striker Michael J.
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