Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1994-05-24
1995-10-31
Moulis, Thomas N.
Internal-combustion engines
Charge forming device
Fuel injection system
123506, 417462, F02M 4114, F02M 5936
Patent
active
054620295
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a fuel pumping apparatus for supplying fuel to a multi cylinder internal combustion engine and of the kind comprising a plurality of cam actuated pumping plungers housed within respective bores defined in a body, the bores at their inner ends communicating with each other and forming a pump working chamber, a cam member having cam lobes formed thereon for actuating the pumping plungers to displace fuel from the pump working chamber, a pump drive shaft for imparting relative rotation between the body and the cam member, a plurality of outlet ports which are connected to the injection nozzles of the associated engine respectively, valve means responsive to the rotation of the pump drive shaft through which fuel displaced from the pump working chamber is supplied to the outlets in turn during successive delivery periods and means for supplying fuel to the pump working chamber between said delivery periods.
In a known form of the apparatus as shown for example in EP-A-0364076, the aforesaid body comprises a rotary cylindrical member which is coupled to the drive shaft and which is located in a bore formed in a fixed housing of the apparatus. The rotary member has a so called delivery passage which communicates with the pump working chamber and opens onto the periphery of the rotary member. The delivery passage is positioned to register in turn with a plurality of outlet ports which open into the bore and which communicate with the outlets respectively so that each outlet receives fuel in turn. The machining of the bore in the housing and the surface of the distributor member requires a great deal of care. If the clearance between the two components is too great, the leakage of high pressure fuel will be unacceptable. On the other hand if the clearance is too small there is a risk of seizure of the two components when the apparatus is in use.
The object of the present invention is to provide an apparatus of the kind specified in an improved form.
According to the invention in an apparatus of the kind specified said body is fixed and the cam member is coupled to the pump drive shaft so as no be rotated thereby, said cutlets being formed in said body and the valve means for feeding fuel to the outlets in turn being housed in said body and interposed between the pump working chamber and the outlets respectively.
According to a further feature of the invention said valve means is defined by the pumping plungers and the cam member is arranged so that prior to displacement of fuel from the pump working chamber one of the plungers is moved to a position to allow fuel to flow from the working chamber to one of the outlets, the plungers being moved to said position in turn so that the outlets receive fuel in turn.
An example of a fuel pumping apparatus in accordance with the invention will now be described with reference to the accompanying drawings in which:
FIG. 1 is a sectional side elevation of part of the apparatus,
FIGS. 2, 3 and 4 are cross-sections on the lines 2--2, 3--3, and 4--4 of FIG. 1,
FIG. 5 is a sectional side elevation on the line 5--5 of FIG. 3,
FIG. 6 is a view of part of the apparatus seen in FIG. 4 taken at right angles thereto, and
FIG. 7-10 show modifications to the the apparatus of FIGS. 1-6.
Referring to the drawings the apparatus comprises a stepped cylindrical main body 10 having a flange 11 which locates against a portion 12 of the housing of the apparatus. The main body 10 defines a spigot portion 13 at its end remote from the flange and the spigot portion is surrounded by a bearing 14 which locates an enlarged portion 15 of a drive shaft 16 about the main body. The drive shaft is supported by further bearings not shown within the housing and in use is driven in timed relationship with the associated engine.
Formed in the body 10 is in the particular example, a pair of transversely extending bores 17 the axes of which are disposed at right angles to each other and normal to the axis of rotation of the drive shaft.
The outer ends of the bores open into slots 18 resp
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patent: 5215449 (1993-06-01), Ilija
patent: 5244354 (1993-09-01), Nicol
patent: 5318001 (1994-06-01), Djordjevic
Lucas Industries Public Limited Company
Moulis Thomas N.
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