Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1996-06-12
1999-02-23
Miller, Carl S.
Internal-combustion engines
Charge forming device
Fuel injection system
123495, F02M 4100
Patent
active
058733469
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a fuel injection pump as set forth hereinafter. In one such fuel injection pump, known for instance from European Patent Disclosure EP-A 0 444 279, the annular slide is embodied as a cylindrical annular disk with flat end faces. One of the end faces, together with the inner bore of the annular slide, forms an encompassing control edge, at which the outlet cross section of the radial bore is opened upon a reciprocating motion of the pump piston. The position of the annular slide is set with the aid of a governor lever combination; one of the levers, via an actuating head, engages a corresponding recess on the jacket face of the annular slide and puts the annular slide into a desired position in accordance with the motion of the lever. In this arrangement, after the radial bore is opened by the control edge, a diversion stream occurs, which is aimed radially and is located in a different angular position relative to the stationary pump housing in the stationary annular slide, depending on the rotary motion of the pump piston in each supply stroke of the pump piston. This embodiment has the disadvantage that the diversion stream sweeps over the flat face of the face end of the annular slide, so that a region of lower pressure forms between the diversion stream and the end face of the annular slide; this lower pressure exerts a force on the annular slide with the effect that the annular slide can move axially upward in the direction of the pump work chamber, within the limits of the possible play between its coupling to the governor lever or the play and resiliency of the governor lever combination. Because of the variable angular position of the diversion stream and the resultant different geometry of the adjacent diversion chamber with the governor and with springs that restore the position of the pump piston, the effects of the motion of the annular slide are variably pronounced. Since on the other hand throttling of the diversion stream occurs as a result of an adjustment of the height of the annular slide, resulting in different times before the relief of the pump chamber has progressed far enough to interrupt the injection. The consequence is accordingly undesired deviations of the injection quantities from one stroke to another.
ADVANTAGES OF THE INVENTION
The fuel injection pump of the invention has the advantage that as a result of the fuel stream deflected at an angle to the radial plane, the effect of the pressure reduction between the fuel stream and the face end of the annular slide and of the various pressure fields in the diversion chamber that are affected by the geometry of the diversion chamber is reduced, and thus the oscillating axial motions of the annular slide within the limits of the mechanical play or possible degrees of freedom of the governor are made uniform, and a reduction in injection quantity deviation is achieved. In addition, a reduction in the forces exerted on the annular slide upon diversion is obtained, which means less stress on the parts that actuate the annular slide.
The fuel injection pump of the invention has the advantage that deflection faces on the annular slide can be achieved in a simple way. In accordance with the advantageous features set forth, such a deflection face can also be effectively disposed on the pump piston. An advantage is that the diversion stream, in fuel injection pumps that function with control of the end of supply, is aimed in the direction of the supply stroke motion of the pump piston.
With the features set forth, by means of the annular face adjacent to the control edge, first the necessary clearance for unhindered relief of the pump work chamber exists. Then because of the achievement of the deflection face, which is transverse to the diversion stream, the aforementioned axial forces are reduced because of pressure differences between the diversion stream and the surface of the annular slide, and because of the geometry of the adjacent diversion chamber, the annular side in the axial direction of t
REFERENCES:
patent: 4082072 (1978-04-01), Johnson
patent: 4763631 (1988-08-01), Fehlman
patent: 5191868 (1993-03-01), Kraemer
Greigg Edwin E.
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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