GB2153450A - A fuel injection pump - Google Patents

Abstract

A distributor type fuel injection pump consists of a plunger 16 that is both reciprocable and rotatable in a bore 22 to distribute fuel in a predetermined schedule separately to each cylinder of the engine. Both the fuel quantity and injection timing are controlled by an electromagnetically controlled spill control valve 38 axially aligned with the end of the bore 22 to define with the plunger and bore a fuel pumping chamber 70. <IMAGE>

Description

SPECIFICATION Afuel injection pump This invention relates in general to a fuel injection pump, and, more particularly, to a fuel injection pump of the plungertype in which the plunger is also a rotatable fuel distributor and is axially integrated with a fuel spill control valve that is electromagnetically actuated to selectively control the volume and timing offuel injection.

A rotatable plunger type fuel injection pump perse is not new. For example, U.S. 4,220,128, Kobayashi, shows in Figure 1 a pump with a plungerthat is both reciprocable and rotatable to distribute fuel to the various cylinders ofthe engine. Aspill control valve sleeve 20 is moved in response to engine speed changestocontrolthefuelflow. However, the spill control valve is not integrated in axial alignment with the plunger, nor is there selective actuation or volume control via electromagnetic means to varythevolume and timing of injection.

U.S. 4,216,752, Galan, shows a rotary distribution type plunger pump with a separate spill control valve that is not integrated axially as a part ofthe plunger barrel, and a minimum oftwo solenoids are required to control movement of the spill valve. The pump plungeralso is not rotatable and a separate fuel distributor is required.

U.S. 4,379,442, Simko, asigned to the assignee of this invention, shows a plungertypefuel injection pump with an electromagnetically controlled spill valve. However, the plunger is not rotatable, it does not act as a fuel distributor, the spill valve is not integrated as a portion ofthe plunger barrel and axially aligned therewith, and a separate plunger and delivery valve and spill valve are required for each cylinder ofthe engine.

According to the present invention there is provided a distribution type fuel injection pump of the plunger type for a multi-cylinder internal combustion engine comprising a housing having an engine driven rotatable driveshafttherein, a stationary pump plunger barrel projecting through the housing and having a bore slidably receiving a single pumping plunger therein, a multi-lobed cam and gear means on the driveshaft engageable with the plungerto rotate and reciprocate the plunger axially along its bore through fuel pumping and intake strokes, a fuel spill valve reciprocatably mounted in the end ofthe barrel opposite the driveshaft and having its axis in axial alignmenttherewith and providing an axial clearance space between the valve and adjacent plunger end to define a fuel pressurisation chambertherebetween, the housing having a fuel fill port and a numberoffuel discharge ports opening into the plunger barrel, the discharge ports being intermittently communicable with axial passage means in the plunger as a function of the rotation and reciprocation ofthe plunger to alternately fill the chamber with fuel while blocking fuel flow th rough the discharge ports and vice verse, and selectively operable electromagnet means fixed to the spill valve for operating the same between open and closed positions to control the flow offuel into and out ofthe chamberfor pressurization ofthe chamber or draining fuel thereform the electromagnet means being selectively operable as to initiation and duration of injection to control variably both the volume and timing offuel discharged.

Further, according to the invention there is provided a fuel injection pump ofthe plungertype, having a single engine driven plunger mounted in a stationary plunger barrel forsimultaneous reciprocatoryand rotary movement, an open-close fuel spill control valve axially aligned with a movably mounted in an end ofthe barrel to define a fuel pressurization chamber between the valve and plunger end, means for admitting fuel to the chamber, the barrel having a plurality of circumferentially spaced fuel discharge ports at the same axial location corresponding in number to the number of engine cylinders, the plunger having passage meanstherethrough connecting the chamberto the discharge ports one-at-atime as a function of rotation and reciprocation ofthe plunger, the passage means being blocked upon rotation to locations between the ports while simultaneously admitting fuel to the chamber, and selectively energized electromagnet means connected to the spill control valve forvariably controlling the opening and closing of the valve for controlling both the volume and timing ofthefuel.

The invention will now be described by way of example with referenceto the accompanying drawing in which: Figure 1 schematically illustrates a cross-sectional view of fuel injection pump assembly embodying the invention; Figures 1 A and 1 B are cross-sectional views taken on planes indicated by and viewed in the direction of the arrows 1A-1Aand 1B-1 B of Figure 1; Figure 2 is a view similarto that of Figure 1, with the parts in diferent operative positions; and Figures 2A and 2B are cross-sectional views taken on planes indicated by and viewed in the direction of the arrows 2A-2A and 2B-2B, respectively, of Figure 2.

As best seen in Figures 1 and 2, the pump embodying the invention is of the plungertype and includes a driveshaft 10 rotated bytheengine in the direction ofthe arrows shown. In the case of a four stroke engine, shaft 10 would be rotated at one-half crankshaft speed. Keyed to shaft 10 is a four lobed cam 12 that engages the lower end 14 of a single pumping plunger 16. Also keyed to driveshaft loins an annulus gear 18 that meshes as shown with a bevel gear 20.

The latter is splined to the end of plunger 16 to rotate it while permitting axial sliding movement of the plunger as a function of rotation of cam lobe 12.

Plunger 16 in this case is rotatably and axially slidably mounted in the bore 22 of a stationery plunger barrel defined in a pump housing 24. The upper end ofthe bore has a stepped diameter at 26 for the reception ofthe lower end 28 of an electromagnetically operated fuel spill control valve assembly 30. The latter includes an elongated stationery sleeve member 32, the lower end 28 being formed with a central bore 34 and a conical valve seat 36. The seat mates with the end of a fuel spill control valve member38to block or unblock bore 34. The valve 38 perse informed with an elongated stem 40 threadedly fixed to the annular plate-like armature 42 of a solenoid 44. The solenoid includes a stationery annular core 46 that is attached as shown to the pump casing 24.The core surrounds spill control valve 38 and is spaced radiallythereform, with suitable coils 48 being wound around the core as shown. The armature 42 is biased upwardly by a spring 49 awayfrom core46toprovidetheconven- tional gap 50 between the two.

The pump housing 24 is provided with a stepped diameter cavity 52, 54 within which the electromagne- tic assembly 30 is located. The smaller cavity 54 is covered bythe stationery core 46 to define a subchamber 56 which communicates through radial holes 58 in sleeve end 28 with a chamber 60 defined between the lower end 28 ofthe sleeve and the spill control valve 38. The larger cavity 52 constitutes a main fuel reservoir supplied from a fuel inlet line 62, the fuel passing through a numberof circumferential- ly arranged passages 64 in the base of core 46 to communicate with chamber 56. Afuel discharge or return to tank passage 66 is intersected by a further passage 68 that connects to the plunger barrel bore 22 to provide one avenue of supply of fuel to the plunger barrel.The large volume of fuel passing from inlet 62 to outlet 66 also cools the electromagnet assembly 30.

As best seen in Figure 1,the upper end of plunger 16 and the lower end of sleeve 32 definetherebetween a fuel pressurization chamber 70. The chamber is supplied with fuel through eitherthebore34from main reservoir 52 when the spill control valve 38 is open, andlorf rom the fuel supply line 68 byway of a number of axially grooved passages or slots 72 in the upper end of plunger 16. During the intake or downward stroke of plunger 16, the axial peripheral passages 72 will align with passage 68, and fuel will flowfreely into chamber 52 from either source.On the other hand, when spill control valve 38 is in its down or closed position, as shown in Figure 2, and plunger 16 is rotated to the position shown in Figure 2, an upward movement of plunger 16 will cut off passage 68 and pressurize the fuel in chamber 70. This will cause the fuel to passdownwardlythrough an axial passage 74 in the plungerto a radially disposed passage 76 best seen in Figures 1 B and 2B. Passage 76 is adapted to be aligned radially on a one-at-a-time basis with a number of fuel discharge ports 77 connected to lines 78, in turn each connected separately to its own fuel delivery valve 80 of the retraction type.

More specifically, the numberoffuel discharge ports 77 correspond to the number of engine cylinders to be supplied with fuel, and would be spaced equally circumferentially atthe same axial location around the barrel of plunger 16. Plunger 16 rotates once for every four axial strokes of plunger 16. Accordingly, the plunger barrel ports 77 are located such that as the plunger moves downwardly on cam 12 through its intake stroke, rotation of the plungerwill misalign the radial passage 76to an inbetween port position shown in Figure 1 B blocking discharge of fuel from axial passage 74to the delivery valves.Simultaneously, the rotative position of plunger 1 6will locate the four peripheral axial slots 72 as seen in Figure 2to align one ofthe slots wit;1 the fuel suply line 68to thereby connect a supplyoffuel to the fuel pressurization chamber70. Atthe same time, with spill valve 38 open, fuel also may be supplied to the chamber 70 from the fuel reservoir 52 through the passages 64, chamber 56, and passage 58 to chamber 60.

During the upward or pumping stroke of plunger 16, the plunger will rotate to the Figures 2A and 2B positions. The peripheral axial passages 72 will be misaligned with the fuel supply passage 68 while the axial passage 74 and passage 76 will be connected to one ofthe four discharge ports 77, as shown in Figure 2B. Simultaneously, depending upon the volume of fuel to be injected, the solenoid 44 will be energized to cause a downward movement of armature42 and a corresponding movement of spill control valve 38 to close bore 34 and permit pressurization of fuel in chamber 70. This fuel thus will be forced through axial passage 74 into the discharge line 78 to the various engine cylinders in succession upon the successive rotation of the plunger 16.

Itwill beclearthatthe electromagnet30 will be energized selectively as to initiation and duration during the pumping stroke of plunger 1 6to selectively control the closing of spill port bore 34to specifically determine the quantity of fuel to be injected as well as thetiming of injection as desired to satisfythe engine requirements.

The construction and operation ofthe retraction type delivery valves 80 is known and the details, therefore, are believed to be unnecessary for an understanding ofthe invention. Suffice itto say that the delivery valve 80 is normally biased to the closed position shown on the left-hand side of Figure 2 by a spring 82. When the fuel pressure acting againstthe lower end 84 of the valve is sufficient to overcome the spring pressure and move the valve to the open position shown atthe right-hand side of Figure 2, then fuel can flow from line 78 into the main fuel chamber 86 and outthrough a passage88to the corresponding engine cylinder.When fuel flow is cut off from line 78 by rotation ob plunger 16 to the Figure 1 B position, decay ofthe fuel pressure in chamber 86 below the force of spring 82 will move the valve 80 into the small bore 90 until fuel communication between bore 90 and chamber86 is cut off. Thereafter, continued movement of the body ofthe valve into the smaller bore until the conical valve portion 92 seats againstthe mating conical seat portion ofthe pump housing 94 will retract a certain mass of the valve out of chamber 86 and thereby decay the presure therein even further, to prevent after-injection of dribbling, in a known manner.

It will be clearthatwhile a retraction type delivery valve has been shown and described, any suitable residual fuel pressure reducing could be substituted therefor.

From the foregoing, it will be seen that the invention provides an economical fuel injection pump consisting of a single reciprocating and rotatable plungerthat is integrated with an electromagnetically controlled spill control valve axially aligned with the plunger at one end to control selectively the flow of fuel through passages in the plungerto individual engine cylinder delivery valves for operation on a one-at-a-time basis in sequence during the pumping stroke of the plunger, the intake stroke of the plunger blocking the fuel discharge ports while simultaneously opening intake portstoafuel pressurization chamberdefined be tween the plunger and spill control valve, the selective control ofthe electromagnet means controlling the volume and duration of fuel injected.

While the invention has been shown and described in its preferred embodiment, itwill be clearto those skilled in the arts to which it pertains that many changes and modifications may be madethereto without departing from the scope of the invention.

Claims (6)

1. Distributiontypefuel injection pumpofthe plungertype for a multi-cylinder internal combustion engine comprising a housing having an engine driven rotatable driveshafttherein, a stationary pump plunger barrel projecting through the housing and having a bore slidably receiving a single pumping plunger therein, a multi-lobed cam and gear means on the driveshaft engageable with the plunger to rotate and reciprocate the plunger axially along its bore through fuel pumping and intake strokes, a fuel spill valve reciprocatably mounted in the end of the barrel opposite the driveshaft nd having its axis in axial alignmenttherewith and providing an axial clearance space between the valve and adjacent plunger end to define a fuel pressurisation chamber therebetween, the housing having a fuel fill port and a number of fuel discharge ports opening into the plunger barrel,the discharge ports intermittently communitating with axial passage means in the plunger as a function ofthe rotation and reciprocation ofthe plunger to alternately fill the chamberwith fuel while blocking fuel flow through the discharge ports and vice verse, and selectively operable electromagnet means fixed to the spillvalveforoperatingthesame between open and closed positionstocontroltheflowoffuel into and out ofthe chamberfor pressurization of the chamber of draining fuel therefrom the electromagnet means being selectively operable as to initiation and duration of injection to control variably both the volume and timing of fuel discharged.

2. A pump as claimed in Claim 1, wherein the fuel discharge ports are circumferentially aligned and spacedfrom one anotherforblockageoftheplunger passage means when the latter is nonaligned with a portand forfilling the ports with fuel one-at-a-time when the plunger passage means is aligned therewith.

3. Afuel injection pump of the plungertype, having a single engine driven plunger mounted in a stationary plunger barrel for simultaneous reciprocatory and rotary movement, an open-close fuel spill control valve axially aligned with a movably mounted in an end of the barrel to define a fuel pressurization chamber between the valve and plunger end, means for admitting fuel to the chamber, the barrel having a plurality of circumferentially spaced fuel discharge ports at the same axial location corresponding in numbertothe number of engine cylinders, the plunger having passage means thereth rough connecting the chamberto the discharge ports one-at-atime as a function of rotation and reciprocation ofthe plunger, the passage means being blocked upon rotation to locations between the ports while simultaneously admitting fuel to the chamber, and selectively energized electromagnet means connected to the spill control valve for variably controling the opening and closing of the valve for controlling both thevolumeandtiming ofthefuel.

4. Apumpas claimed in Claim 3,the meansfor admitting fuel to the chamber including a fuel reservoir connected to the spii I valveforflowthere- past when open, and a supply passage openable into the plunger bore, the plunger having circumferentially spaced passages alternately connecting or blocking the flow of fuel from the supply passage to the chamber, the plunger passage means comprising intersecting axial and radial passages connecting the chamberto the discharge ports when rotationally aligned therewith.

5. A pump claimed as in Claim 4, including an individual residual fuel pressure reducing device connected to each ofthe discharge ports and to its corresponding engine cylinder for the delivery of separtevolumes of fuel thereto.

6. Afuel injection pump substantially as herein before described with reference to and as illustrated in the accompanying drawing.