US 2279010 A
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Description (OCR text may contain errors)
April 7, `1942. w. M. NICHOLS l2,279,010
FUEL INJECTION APPARATUS Filed Aug. 19, 1941 A TORNE Y der (not shown).
Patented Apr. 7, 1942 FUEL INJECTION APPARATUS William, M. Nichols, Auburn, N. Y., assignor to American Locomotive Company, New York, N. Y., a corporation of New York Application August 19, 1941, Serial No. 407,449
(ci. 12s-139) 3 Claims.
This invention relates to fuel injection apparatus for an internal combustion engine.
An object of the present invention is to provide a fuel injection apparatus for a` cylinder of an internal combustion engine, having an injection nozzle and injection pump for attachment to a cylinder head, provided with a spill for effecting a sharp termination of injection by a hydraulic impact closing the nozzle valve.
A further object is to provide a fuel injection apparatus having an injection nozzle and injection pump as aforesaid, for attachment to a cylinder head, and a metering pump remote from the injection pump and connected thereto by piping, thereby preventing overcrowding of the cylinder head, and means between the pumps, preferably a retraction valve, permitting the aforesaid spill.
Other and further objects of this invention will appear from the following description, the accompanying drawing'and the appended claims.
The accompanying drawing forming a part of this application is a longitudinal central lsectional view of a fuel injection apparatus, parts being shown in full and parts being broken away.
In its preferred embodiment, the fuel injection apparatus, indicated generally by the reference numeral I, of the present invention includes four parts, namely a fuel oil metering pump 2, a retraction valve 3, a fuel injection pump 4 and an injection nozzle 5. The metering pump sends a measured quantity of fuel to the fuel pump, which latter pumps it to the injection nozzle for injection into the engine cylintraction valve is preferably disposed in (integral with) the metering pump as shown, and as thus disposed -forms a unit with the metering pump. The retraction valve may-be situated at other locations between the metering pump and fuel pump if desired.
The retraction valve, at the il.'
There is an injector for each engine cyland cylinders arranged around a single cam shaft for operation by-a single adjustable cam. Such a multiple metering pump is shown in paten-t to Wahlmark, No. 2,031,346, February 18, 1936. The amount of fuel pumped by the metering pump to the .injection pump is varied by varying thelength of the metering pump plunger stroke. However, metering by pump,2 may be adjusted by other means if-desired.
The fuel metering pump 2 includes a casing l, a cylinder 8 therein, a fuel inlet port 9, a fuel discharge port I0, and a plunger II in the cyll.
I stop I5 formed in the head. a valve element I 1 nor- The metering pump may be a separate appa- 'A' employed consisting of a plurality of plungers 15 mally disposed on a seat I8 formed in the casing around cylinder I3, a spring I9 returning the element to and holdingL it upon its seat, a piston 2D normally disposed in cylinder I3, and a iluted guide 2I for the piston, the valve element Il, piston 20 and guide 2I being formed as an integral structure. Delivery pipe 6 is secured t0 a nipple forming part of head I4 by a nut 22, and head I4 is provided with a passage 23 connecting pipe 6 with chamber I5.
The operation of the fuel metering pump and retraction valve is as follows: As shown in the drawing, the downward stroke of the plunger II is its suction stroke, and the upward stroke is its pumping stroke. On its suction stroke it draws fuel from a reservoir (not shown) into cylinder 8 through port 9, and on its pumping stroke,
after plunger II has closed port 9, it pumps fuel to the retraction valve 3.
The fuel being pumped acts .against piston -20 of the retraction valve, forcing piston 20 upwards and valve element I'l off its seat I8, thereby compressing spring I9. When piston 20 passes completely out of cylinder I3 (valve element Il engaging stop I6), fuel will be pumped by plunger II -past the retraction valve-due to the fluting of guide 2| and stop IG, into the delivery pipe 8 and therefrom to the injection pump 4.
When plunger I I starts en its downward str: kc again, spring I9 forces valve element Il and piston 20 downward, providing a space for the spill as aforesaid. Valve element I1 acts as a conventional one-way ilow delivery valve. Delivery lpipe 6 is secured by a nut 24 to a nipple forming part of the injection pump casing 25. Casing 25 is disposed on and secured to injection nozzle casing 26 by a threaded connection 21.
Casing 25 provides a chamber 28, a. cylinder 29, a passage 30 leading` from pipe 6 to cylinder 29, and a drain passage 3| leading from cylinder 29 to the exterior.- v
Casing 26 is hollow providing a bore 32 open at both ends and having a shoulder 33 therein. A nozzle housing 34 is disposed in the bore. At one end it is in engagement with casing 25 and at its other end projects beyond casing 26 through the shouldered open end thereof. Nozzle'housing 34 has a shoulder 35 engaging shoulder 33 andl is securely held in the bore by casing 25.
Nozzle housing 34 is shown made of two pieces in order to simplify ,its manufacture, but it. will be described hereinafter as if it were made in one piece. It includes a central bore providing a cylinder 36, a chamber 31 above the cylinder, and a chamber 38 below the cylinder. A passage 39 connects passage 30 with chamber 31 and a passage 40 connects cylinder 29, at the bottom thereof, with chamber 38. A passage 4| connects chamber 38 with jets 42, and a valve seat 43 is provided at the jointure of chamber 38 and passage 4|.
A valve element 44 is disposed in the bore of nozzle housing 34. It includes a piston' 45 in cylinder 36 and a valve needle 46 formed integrally with the piston, needle 46 and seat 43 forming a valve. A spring 41 disposed in chamber 31 normally holds the piston 45 downward with needle 46 in engagement with seat 43. A stop 48 limits ,upward movement of the piston 45 and compression of spring 41. Needle 46 is of smaller diameter than piston 45 providing a push 'rod (not shown) connected to the engine camshaft for operating the injection pump. A split ring 59 disposed in a groove in the upper end of chamber 28 prevents accidental movement of the tappet out of the chamber.
When the piston 52 is at its lowermost position, as shown in the drawing, which is the position at the termination of injection, groove 54 is opposite and in communication with a passage 60 which opens into passage 39. Passage 60 is controlled by the lower edge 6| of piston 52 and the lower edge 62 of the groove 54. The upper edge 63 of the groove 54 controls passage 3|), as will presently appear.
An oriced plug 64 is disposed in passage 39 between passages 60 and 30, the orifice 65 of the plug being small in comparison with passages 60 and 30, thereby restricting the ow from and to passage 39.through orifice 65.
The operation of the fuel injector is as follows: When the piston 52 is in its uppermost position, groove 54 is opposite passage 30 and l therefore fuel under metering pump pressure is forced into groove 54, through passage 55 into the lower end of cylinder 29, and through passage 40 to chamber 38. The pumping strokes of plunger and piston 52 will be timed to insure the metered charge entering the cylinder 29 before passage 30 is closed by edge 63.
On the downward or pumping stroke of pis-l ton 52, edge 63 will close passage 30 substantially simultaneously with the closing of passage 60 by shoulder 49 therebetween disposed in cham-I ber 38.
Passages 39 and 40 are formed partly in casing 25 and partly in nozzle housing 34 and therefore nozzle housing 34 is secured to casing 25 against relative rotation by a key 5|) to insureV alignment of the passages in each. A groove 5| formed in the nozzle housing between the two parts thereof'aforementioned insures a free way for passage through the nozzle housing.
The injection pumpv 4 further includes a plunger formed of a piston A52 and astem 53 integral therewith, the piston and stem being disposed in cylinder 29. A circumferential groove 54 is provided in the piston and a' passage 55 is formed through the piston. connecting groove 54 with cylinder 29 at the bottom of piston 52. An oil collecting circumferential ,groove 56 is formed in the stem 53 adjacent passage 3|. Groove 56 collects lubricating oil passing downward along the stem and fuel oil passingupward along the piston, and passage 3| drains groove 56 to the atmosphere, thereby preventing adulteration of luber 31 to substantially injection pressure, which bricating oil by fuel oil and of fuel oil by lubrieating oil. 'I'he stem 53 Aabove groove'56 is lubricated by lubricating oil from chamber 28 and the stem below groove 56 and-the piston 52 are lubricated by fuel oil. y
A tappet 51 is secured to the upper end of stem 53V, and works in chamber 28. A spring 58 normally`urgestappet 51 upwardly. i. The uppermost position of tappet 51 is determinedby a cam or -will presently appear.
Prior to nozzle valve opening, a suflicient load is exerted on element 44 to insure complete fuel atomization when needle 46 opens passage 4|. As the load on the engine varies, the timing of the opening of the valve varies, the valve being opened sooner at high loads than at low loads.
Termination of injection begins when edge 62 uncovers passage 68. As piston 52 is not adjustable, this always happensat the same time for all loads. Thus a uniform termination of injection is obtained. When this happens, pressure in passage 39 and chamber 31, having been relieved, as aforesaid, is lower than injection pressure. At luncovering of passage 60 there is a spill of fuel at injection pressure through passage 60 into passage 39. This spill reduces the pressure in chamber 38 and passage 40. At the same time it increasesthe fuel pressure inchamaugments the spring pressure and effects quick closing of needle 46,-sharply. terminating injection. The quick closing of the-needle is eiected by what may be termed a pressure flow to th'e valve deliveringa hydraulic impact on top of pis-- ton 45 due to the spill. As needle 46 closes there is an equalization of fuel pressures inpassages 39 and 48, the apparatus then-being ready for the next injection cycle. 4 l
It will be seen from the foregoing description that the quick closing ofthe valve by the added hydraulic pressure or impact prevents harmful necting said metering and injection pump cylin-` `dribbling through the jets 42 at the termination of injection.- In accordance with the present invention, the needle is closed by an increase in pressure on top of the needle and not by a degeneration of vpressure beneath the needle. Thus at needle-closing injection is at high velocity, causing high atomization and scavenging of passage 6I. This augmenting closing pressure enables a lighter spring to be employed, less pressure to open the valve being thereby required as at valve-opening, the augmenting closing pressure `is not present. a
By using a separate metering pump and a separate injection pump in the apparatus of the present invention, the metering pump, which only measures the quantitypf fuel, may be placed at any convenient place where there is suiiicient available space although remote from the injection nozzle, as thelength oftpiping between the two pumps would not affectA the metering of the fuel. Thus overcrowding ofthe cylinder head is prevented. The injection pump may be placed in close proximity to the injection nozzle, in fact in the same casing as in the present embodiment, thereby avoiding all objectionable tubing between the injection pump andinjection nozzle, 4
which tubing would interfere with accurate delivery of fuel to the injection nozzle.
While there has been hereinbefore described an I approved embodiment of this invention, it will The invention claimed and desired to be secured by Letters Patent is:
1. A fuel injection apparatus for an internal combustion engine comprising a fuel metering pump having a cylinder; a. fuel injector including a fuel injection nozzle and a fuel injection pump having a cylinder; a fuel delivery passage conders; Aandl a retraction valve disposed in said passage. 1
2. A fuel injection apparatus for an internal combustion engine comprising a fuel metering pump; a fuel injector;` and a fuel delivery pipe connecting said pump and injector, said injector including an injection jetvfor injection of fuel into a cylinder of said engine, a valve for controlling said injection, a cylinder for said fuel, a piston in said fuel cylinder for pumping the fuel therein, a passage from said fuel cylinder for conducting pumped fuelto said jet, said valve having a valve element provided with opposite faces, a spring opposing opening of said valve,
one of said faces being acted upon by saidv pumped fuel to open said valve, and a spill passage leading from said fuel cylinder to the other of said faces, the spilled `fuel causing a pressure flow hydraulically augmenting closing of said valve to sharply terminate injection.
3. A fuel injector comprising a cylinder for fuel; a fuel pumping piston in 'said cylinder; an injection jet; a valve for controlling said jet, said valve including a seat and a needle therefor; a valve cylinder; a valve piston disposed in said valve cylinder and connected to said needle for opening and closing said valve; a spring normally holding said valve'piston in needle'valve-closed position, said injector further comprising a passage connecting said fuel cylinder with said valve cylinder at the end of said valve piston adjacent said needle whereby the pressure of said pumped fuel will act on said .valve piston to open said valve, and a passage connecting said fuel cylinder with said valve cylinder at the other end of said valve piston; and spill means in said.