US2287702A - Fuel injection device - Google Patents

Description

"` June 23, 1942.v w, M, NlcHoLs l FUEL INJECTION DEVICE:

Filed May 15, 1941 amm-5' Patented June 23, 1942 FUEL INJECTION DEVICE william M. Nichols, Auburn, N. Y., assignor to American Locomotive Company, New York, N. Y., a corporation of New York Application May 15, 1941, Serial No. 393,643

1 Claim.

This invention relates to fuel injection devices the reduced speeds of the range is undesirably correspondingly reduced, due to the reduced velocity of the pump. Also when the engine is running at the higher, speeds of the range, extreme pressure waves are created in the pipe between the fuel pump and injector nozzle, due to the sudden spill of the fuel to terminate injection. These pressure waves have a tendency to open the nozzle valve, thereby causing a second and perhaps a third injection at a timeundesirable for proper operation of the engine. Furthermore, as the conventional pump, in a single pumping operation, is requiredto build up the pressure to a point Where the nozzle valve will open, then to maintain the pressure during injection, and thereafter to spill `the fuel to terminate injection, the period of injection isvcon-Y sequently undesirably long. The elimination of one or more of these steps permits a shorter injection period to be obtained.

It is an object of the present invention to provide a fuel injection device which will not' lieve the aforementioned undesirable character` 1s ics.

A further object is to provide an improved injector nozzle.

A further object is to provide a fuel injection device in which two separate fluid pumps coact toI effect injection, one pump providing fuel to the injector nozzle, and the other providing a .fluid for actuating the. nozzle valve.

Other and further objects of this invention lwill appear from the following description, the accompanying drawing and the appended claim.

Referred to the drawing forming a part of the present application, Figure 1 is a diagrammatic view in vertical central section illustrating one embodiment of the fuel injection device of the present invention, parts being shown in full and other parts broken away; Fig. 2 is a diagramwhen fuel is delivered to the nozzle, provided the.

invention, parts being brokenaway; and Fig. 3 is a diagrammatic plan view of an internal combustion engine, showing the arrangement of the fuel injection devices therefor of the type illustrated in Fig. 1. y

Referring to Fig. 1, the fuel injection device, indicated generally by the reference numeral I, includes an injector nozzle 2, a fuel pump 3 connected to the nozzle by a pipe 4, and a smaller valve-actuating fluid pump 5 connected to the nozzle by a pipe 6.

The fuel pump 3 is illustrated as of the plunger type, although other types of pumps may be em-y ployed if desired. Similar remarks apply to pump 5, but the following description will be limited to the type of pump shown, as it has been found that this type is especially well adapted to the present invention.

Pump 3 includes a body 1 having a cylinder a cap 9 therefor, fuel inlet pipe I0, fuel discharge passage I I, plunger I2 and check valve I3. Pump 5 similarly includes a body I4 having a cylinder I5, cap I6 therefor, fluid inlet pipe I1, uid discharge passage I8, plunger I9 and check valve 20. I

Pump 3 controls the period .duringwhich fuel is delivered to the nozzle 2. Pump 5 controls the period during which the nozzle valve (later to be described) is maintained in open position. In-

`jection may commence when the nozzle valve is l opened, provided fuel under pressure has already been delivered to' the nozzle, or it may commence nozzle valve is already open. Similarly injection may be terminated by the closing of the nozzle 4 valve or by pump 3 terminating delivery of fuel to the nozzle. e

It has been found preferable to operate the pumps so that pump 3 begins to pump before and continues to pump after pump 5, so that a constant supply of fuel under'pressure is available during the periodin which the nozzle valve is kept open by pump 5. Thus pump 5 determines the beginning and the end of injection. This insures a quick commencement of injection and a quick termination, avoiding dribbling of fuel into the engine cylinder at the beginning and lend of injection, which dribbling effects poor combustion `in the cylinder. This is an added advantage of the present invention.

Where,.as in the present case, the commencement and termination of injection are controlled by` the pump 5, Vpump 5 must be adjustable ,to permit the engine to run at different speeds.

matic view, in elevation, of a modification of the 5.5 Adjustable pumps4 are well known and for this f reason pump has been shown more or less diaadjusted to change the speed of the engine.

grammatically in Fig. 1, no detailed description of an adjustable pump being deemed necessary. An adjustable pump which may be employed to do the work of pump 5 is shown in patent to Baur, 1,871,872, dated August 16, 1932.

Fuel pump 3 may be adjustable or not, depending upon the manner in which it is employed. When an adjustable fuel pump is to be employed, it may be similar to the pump of the above mentioned patent. While, as stated, the pumps are shown diagrammatically, it will be noted, however, that the metering groove of the patent which is responsible for the adjustability, is indicated on each of the plungers I9 and I2 of the pumps 5 and 3. Obviously, when pump 5 controls the commencement and termination of injection, pump 3 need merely supply enough fuel to nozzle 2 so that fuel under pressure will be available during the time the nozzle valve is in open position. g If a by-pass is provided to prevent undesirable pressures at certain speeds, a pump 3 can be utilized which is not adjustable. However, it has been found that a pump 3 which is adjustable similar to pump 5 works very well, the adjustment of pumps 3 and 5 bearing a relation to each other so that they can be simultaneously In a similar manner, if commencement and termination of injection are to be controlled by pump 3, then it would necessarily be pump 3 which would be adjustable, and a non-adjustable pump 5 could be employed.

As pump 5 need only supply uid for opening the nozzle valve, its delivery need not be as large as the delivery of the conventional fuel pump. It is-therefore possible to get more accurate adjustments and quicker responses in pump 5 in order to actuate the nozzle valve than is possible in a conventional fuel pump which operates to both inject fuel and actuate the nozzle valve. This is an added advantage `of the present invention.

Pumps k3 and 5' may be operated from a common cam shaft (not shown) and in such case they would be on the same side of the internal combustion engine, indicated generally by the reference numeral 2| (Fig. `3). However, it has been found desirable to employ separate cam shafts for pumps 3 and 5. These cam shafts can be arrangedend to end so that the arrangement of the pumps can be the same as when a single cam shaft is employed. The purpose of employing separate cam shafts is to provide for adjustment of one relative to the other in order that the relative action of the plungers of pumps 3 and 5 can be predetermined. Ordinarily the plunger I2 of pump 3 will start its stroke before the plunger I9 of pump 5 and the cam shafts will be so adjusted, the cam. shaft for pumps 5 being adjustable and the cam shaft for pumps 3 being fixed.

Nozzle 2 is disposed over the center of the engine cylinder 22 into which it injects fuel, and is supported by the cylinder head in its vertical position shown in Fig. 1. Nozzle 2 includes a casing 23 which has a fuel receiving part or chamber 24 which is connected to pipe 4 by an inlet port 25 and which opens into the engine cylinder 22 by means of a passage or injection port 26 and jets 21. A valve seat 28 is formed around the chamber end of passage 28 and a nozzle valve 29, forming a part of a valve element 30, normally engages this seat, closing passage 28.

Casing 23 further has a. valve-actuating fluid chamber 3| which is connected to pipe 6 by an inlet port 32. A cylinder 33, of a smaller diameter than the chamber 3l, opens at one end into chamber 3| and a piston 34 is disposed in the nozzle cylinder. Piston 34 is connected to nozzle valve 29 by a valve stem 35 which extends through chamber 3| and through a guide-forming passage 36 extending from chamber 3| to chamber 24. The valve stern 35 fits in close sliding engagement in the guide, preventing passage of fluid from one chamber to the other chamber. However, if the fluid pumped by pump 5 is fuel oil,'then obviously intermingling of the contents of the chambers will be immaterial.

Casing 23 further has a chamber 31 in which is disposed an energized spring 38. In the drawing the casing is shown formed of two parts, namely a body 39 and a hollow cap 40, the cap providing chamber 31 and being secured to the body by threads 4I'. The spring presses at one end against the cap and at the other end against a seat 42 which is supported on a projection 43 formed integrally with the piston 34, the projection, piston, valve stem and nozzle valve all being integral parts of the valve element. Thus spring 38 holds the nozzle valve 29 against seat 28, normally closing passage 26, and returns nozzle valve 29 to this position after it has been raised by fluid from pump 5. A stop 44 is provided in the cap limiting the lifting of the valve element. While the pump 5 has been described as adapted Ato open the nozzle valve and the spring 38 'to close it, it will be understood that The particular construction lof nozzle 2 showinl and described is by way of illustration only, and

various other suitable designs may be employed.

All such various types of nozzles are contemplated as within the scope of the present invention.

Valve stem 35 is of a smaller diameter than piston 34, thereby providing a shoulder or piston head 45 against which the valve-actuating fluid operates.

As pump 5 operates to merely push the piston upward., the valve-actuating fluid.I may be a fluid which is trapped between the pump plunger I9v and the piston 34. However, as considerable heat is generated in the valve-actuating fluid, it is contemplated bleeding off a small amount of fluid through a bleeder port 48 formed in the chamber 3| for each operation of the plunger I9. `.This fluid is replaced by fluid entering cylinder |5 through pipe I'I. The fluid which passes through port 48 is returned to the source of supply by pipe 41.

One of the Ways of operating the fuel injection device of Fig. 1 is as follows: Fuel under pressure is pumped to chamber 24 by pump 3 and fluid under pressure is pumped to chamber 3| by pump 5. When the pressure in chamber 3| is sufficient to overcome the resistance of spring 38, the nozzle valve 29 is lifted off the seat 28, and, due to the operation of plunger I2, the fuel is injected into the engine cylinder. As the fuel will be at a high pressure in chamber 24 before nozzle valve 29 is lifted, injection will commence very quickly, vinsuring the injection of properly sprayed fuel and eliminating the dribbling in of poorly sprayed fuel, which dribbling often occurs when the nozzle valve is opened by the fuel under pressure. When plunger I9 has reached the end of th'e delivery portion of its `the delivery portion of its stroke.-

lstroke the pressure in chamber Il is dropped and spring 39 quickly returns piston 34 which effects rapid` closing of nozzle valve 29. Fuel is-being 'injected into the engine cylinder in 'properly sprayed condition'up to the moment nozzle valve 29 closes, as plunger I2 is still on bling is prevented at termination of injection. The harmful effects of dribbling are well known and no further comment is deemed necessary. `Suffice it to say that if poorly sprayed fuel enters the cylinder, then poor combustion results. Pump 9 visadapted to supply fuel properly to the engine at low speeds as well as at high speeds, for -although at low speeds the pump plunger has a reduced velocity, thiswis,(minnen-V sated for by the fact that the pump canpump a large supplyv of fuel under pressure, no part of the plunger stroke being needed for other' steps. Thus at reduced speeds, when the nozzle valve 29 is raised, the fuel .in vchamber 24 is r under suitable pressure to properly spray it,

duced thereby in pipe I may be provided for,

taking into account the relativesize of piston 34 and strengthof spring 9|, such that there will be no pressure waves produced in pipe 9 yof a magnitude sufficient to operate the valve.

There is an injection device I for eachcylin- Y der of the engine, as shown in Fig. 3. However, as pump 3 functions only to supply fuel under .pressure to chamber. 24, it is not necessary that there be a pump l for each cylinder. Thus, in Fig. 2 a modication is shown in which `a single pump 3 provides fuel to a plurality of injector nozzles 2'., all the pipes 4' branching from a single supply or pipe 49. 'I'he pump 3' is shown similar to pump 3. However, as it must pumpmore fuel than pump 3, it should be larger in order to maintain a pressure in pipe 49 suitable for injection, or if desired it can be given Thus dribmore reciprocations engine crankshaft rev-A olution. That is'I to sa pipe 49 acts as a reservoir for. fuel under pressure so that a supply is always available, check valve I3' preventing` backward flow of fuel through pipe 49. Pump 9' may take care of several injector nozzles, depending upon its pumping capacity. Thus, for instance, in a six-cylinder engine, there might be three pumps 3' instead of six, as in the embodiment of Fig. 1.

While there have been hereinbefore described approved embodiments of this invention. it will be understood that many and various changes and modifications in form, arrangement of'parts andy details of construction may be made thereto without departing from the spirit vof the invernn tion, and that all such changes andmodications as fall within the scope of theappended claim are tion.

The invention claimed and desired to be se- Y 'cured by Letters Patent is:

Fuel injection apparatus for supplying fuel to an internal combustion engine cylinder comprising acasing having a fuel injection port in one end thereof provided' with a valve seat,1ra

fuel chamber adjacent said seat, a piston cylinder, and' a wall separating said chamber from said cylinder having an orifice extending therethrough: a unitary valve element including a control valve for said seat, a piston .in said cylinder spaced from said wall providing a` chamber for working fluid, and a stem extending through and closing said orifice and rigidly connecting said .valve with said piston: apumping device communicating with said fuel chamber for supply of fuel thereto; another pumping device communicating with said working fluid chamber for supplying working fluid thereto and for alternately producing fluid pressure and release of same therein whereby under said pressure 'said piston vis moved in one direction to move said valve to port-open position; and a spring bearing on said piston for moving said' piston in the opposite direction when said pressure is released for moving said valve to portclosed position, said spring being compressed by said piston during its first said movement.

WILLIAM M. NICHOLS. v

contemplated as a part of this inven-

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