Pumps – With condition responsive pumped fluid control – Pressure responsive relief or bypass valve
Patent
1994-03-07
1995-12-26
Bertsch, Richard A.
Pumps
With condition responsive pumped fluid control
Pressure responsive relief or bypass valve
417490, 417434, 417440, 417504, 123506, F04B 4900, F04B 5310
Patent
active
054782139
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a fuel injection pumping apparatus for supplying fuel to internal combustion engines.
Examples of such apparatus are shown in Eurpean patent documents EP-A-0343759 (corresponding to U.S. Pat. No. 4,936,755) and EP-A-0423958(corresponding to U.S. Pat. No. 5,119,786). In such apparatus the maximum stroke of the piston is limited and is arranged to be at least just sufficient to absorb the total volume of fuel which can be displaced by the pumping plunger during its inward stroke. If in such apparatus the piston should seize within its cylinder or if the resilient biasing of the piston should fail then in the former case, the piston will be unable to move to absorb the spilled fuel and in the latter case if the piston is not already at the limit of its stroke, it will very quickly assume its limiting position. In both cases therefore irrespective of the operation of the spill valve the total volume of fuel displaced by the pumping plunger will be delivered to the associated engine. The increase in fuel flow to the engine will result in uncontrolled acceleration of the engine and the vehicle which is driven by the engine.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide an apparatus of the kind specified above in which the aforesaid risk is minimized.
According to the invention in an apparatus of the kind specified safety valve means is provided to allow escape of fuel from the cylinder in the event that the fuel pressure in the cylinder increases to a value which exceeds the pressure required to move the piston against the action of its resilient loading but is less than that required to displace fuel through the outlet.
The apparatus of the invention includes a pumping plunger mounted in a bore, the plunger and the bore defining a pumping chamber, a cam operable to effect inward movement of the plunger to displace fuel from the pumping chamber, an outlet from the pumping chamber through which fuel displaced from the pumping chamber can flow to an associated engine, fuel supply means for completely filling the pumping chamber with fuel prior to inward movement of the plunger by the cam, a spill valve operable to spill fuel from the pumping chamber thereby to control the flow of fuel through the outlet, an accumulator cylinder into which the fuel which flows through the valve flows and a resiliently biased piston in the cylinder, the piston being displaced by the spilled fuel flowing into the cylinder and acting to return the spilled fuel to the pumping chamber before the next inward stroke of the pumping plunger.
BRIEF DESCRIPTION OF THE DRAWING
An example of an apparatus in accordance with the invention will now be described with reference to the accompanying diagrammatic drawings wherein:
FIG. 1 is a cross-sectional view of a preferred embodiment of the invention; and
FIG. 2 is a view similar to FIG. 1 of a second embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWING
Referring to the drawing the apparatus comprises a body 10 in which is formed a bore 11. Extending from one end of the bore 11 is an outlet 12 which in use is connected to a fuel injection nozzle 12A of an associated engine.
Slidable in the bore is a pumping plunger 13 and the inner end of the plunger 13 together with the inner end of the bore define a pumping chamber 13A from which the outlet 12 extends.
The plunger is movable inwardly by an engine driven cam 9 and is movable outwardly by means of a spring 8. During the outward movement of the pumping plunger a port 14 formed in the wall of the bore 11 is uncovered by the inner end of the plunger and the port 14 is connected to a source 7 of fuel under pressure so that the pumping chamber 13A is completely filled with fuel prior to the inward movement of the plunger by the cam.
In order to control the quantity of fuel which is supplied through the outlet 12 to the associated engine a spill valve generally indicated at 16 is provided comprising a valve member 20 engagable with a seating 18
REFERENCES:
patent: 839331 (1906-12-01), Stevens
patent: 2575955 (1951-11-01), Hatch
patent: 4497345 (1991-03-01), Dahlmann
patent: 4936755 (1990-06-01), Greeves et al.
patent: 5027776 (1991-07-01), Nicol
patent: 5044899 (1991-09-01), Nicol
patent: 5119786 (1992-06-01), Collingborn et al.
Harris Kenneth M.
Tomsett Derek W.
Bertsch Richard A.
Kim Ted
Lucas Industries Public Limited Company
LandOfFree
Fuel injection pump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fuel injection pump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel injection pump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1364523