US1855443A - Fuel pump for internal combustion engines - Google Patents

Description

` April 26, 1932. Q R ERlCSON 1,855,443

FUEL PUMP FOR INTERNAL COMBUSTION ENGINES Filed April 22, 1929 Patented Avpr.. 26, l 932 UNITED STATES PATENT OFFICE GEORGE R. ERICSON, OF ST. LOUIS, MISSOURI, ASSIGNOR TO CARTER CABB'UBETOB GOR- PORATION, F ST. LOUIS, MISSOURI, A CORPORATION Ol' DELAWARE FUEL rtm1 ron INTERNAL conBUsTIoN. ENGmEs Application led April 28, 1929. Serial N0. 357,208.

Figure 1 shows a vertical cross section of,

a fuel pump constructed according to my invention, together with parts of an internal combustion engine in sectionand in diagram. Figure 2 shows a side elevation of my fuel pump.

Figure 3 is a sectional view of the plunger for my fuel pump.

The reference numeral 1 indicates the engine housing or crank case of an internal combustion engine. The housing yis provided with an oil pan 2 to cover the open lower end thereof, and this contains, in operation, a body of oil 3. The engine has the usual crank shaft 4 mounted in a bearing 5. A. web 6 supports the bearing 5 and also the bearings for the cam shaft 7. The cam shaft carries a cam 8 which operates a tappet 9. This tappet recipro- 80 cates in aguide 10 and operates a valve stem 11 which controls the passage of gas into or out of the combustion chamber. This valve is of the usual poppet type and may be either the valve for the inlet or exhaust. The

conventional spring 12 is provided for normally holding the valve in closed position. The cam shaft, or `some other suitable part of the engine, carries a gear '13 which engages a gear 1l mounted on a shaft 22 which rotates in bearing 23 and drives the conventional ol pump 15 of the engine. This pump 15 has an inlet 16 and an outlet conduit y17 through which oilis supplied by the pump to the conduit system 18 in the crank shaft which leads to the main bearings of the engine.

In the operation of the engine, oil is thrown by centrifugal force from the crank shaft and other moving parts of the engine, and

the interior of the casing 1 is filled with a fine mist or spray. A small port 19 is pro-` vided in the upper wall of the crank case and provides communication 'between the crank case and the chamber 20 in which the tappet, valve stem, and valve spring are located. The oil mist also pervades the chamber 20 and lubricates the tappet, the valve spring, and

the stem of the valve 11. The oil collects on the surface of these parts and slowly drains downtherefrom, eventually finding its way .0- back into the crank case either through the opening 19 or by working in the walls of the tappet 9. A removable cover plate 21 ispro vided to close the open side of the chamber 20. i

The engine is provided with a conventional 05 intake manifold, a fragment of' which is shown at 24, a carburetor 25; a fuel tank 26 of conventional construction is also provided. The carburetor, manifold, and fuel tank are shown in diagram on a much smaller scale 10 than the parts of the engine which are shown on sections, and there is no significance in their location on the drawing, it being the intention merely to indicate the use of the ,fuel pump hereinafter described.

The parts thus farI described are more or v less conventional, and it has only been the intention to describe the general characteristics of the type of engine to which my invention is intended to be applied. While I have shown an oil pump, it will be understood that the `invention is also applicable to engines in which the oil is circulated by any other means, as for instance, by splash. Also, it will be understood that the oil might be supplied tothe chamber 20 directly from a pump and that this chamber might, if desired, be maintained substantially full of oil as in a certain well-known type of construction.

According tothe present embodimnt'of 90 my invention, I provide an opening 27 in the cover plate 21 and attach a downwardly inclined operating arm 28l to the valve stem 11 or to some other part of the valve operating mechanism. In the present case, the arm 28 is 95 of sheet metal having a cylindrical formation 29 which snugly fits the outside of the valve stern 11. The usual key 30, or other means, is provided at the end of the v`valve stem to support the arm 28 against the thrust of the 100 spr The pump casing 31 defines thel cham r 32, having ano n side which registers with the opening 2 in the cover plate. Suitable lugs 33 are provided, and these have holes 34 to receive bolts by means of which the pump may be secured to the cover plate.

The pump has a cylinder 35 extending downwardly from the lower part of the chamber 32, a piston 36 for the cylinder is provided, and the upper part of the piston is provided with spaced collars 37 defining an annular groove therebetween. This groove receives a suitable yoke 38 which is formed on the end of the operating arm 28. The plunger may also be provided with packing grooves 39, if desired. The chamber 32 has a downwardly extending well 32a which surrounds the upper part of the plunger.

In view of the rapid reciprocation to which the plunger is subjected, its construction is as light as possible, and it is preferably bored, as at 40, for lightness. If desired, a very light material, such as aluminum, or one of its alloys, may be used. The lower end of the cylinder is provided with an inlet check valve l41 normally held in closed position by a coiled spring 42. The inlet side of the check valve communicates with an'opening 43 in the lower end of the pump casing, and this opening is formed to receive any suitable pipe coupling means and is connected by a pipe, indicated at 44, to the fuel tank 26 so that fuel will be drawn from the tank in the normal operation of the pump. The lower end of the cylinder 35 is provided with an outlet check valve 45 normally held in closed position by a coiled spring 46, and the discharge side ofthe check valve communicates with an opening 47 which is formed to re- 'ceive a pipe coupling and to be connected by a pipe indicated at 48 to the conventional carburetor 25.

In order to avoid discharging more fuel to the carburetor than is required, a relief valve 49 normally held in closed position by a coiled,

spring'50 is provided. This valve controls a passage leading from the discharge outlet of the pump to the inlet of the pump, the con-v nection in each case preferably being outside of the check valve from the pump, so that when a predetermined pressure is exceeded, the excess will be returned to the supply tank.

The length of the cylinder is very much longer than the stroke, and I may also provide one or more interchanging chambers 51 and 52 which communicate with the cylinder but are otherwise sealed. These chambers areso formed as to have considerable capacity and are for 'the purpose of retardingthe ready interchange of gasoline and oil between the opposite ends of the cylinder. It will be understood that the ends of the chambers 51 and 52 are closed by suitable means, such as plugs 60.

The operation and arrangement of the device is as follows:

When the engine is in operation, the valve 11 is reciprocated by the tappet 9 which, in turn, is operated by the cam 8 on the cam shaft. This reciprocation carries the arm 28 with it and thereby reciprocates the plunger 35. The other stroke of the plunger 36 opens the check valve 42 by -suction and draws gasoline or other fuel from the tank 26 into the cylinder. The down stroke of the plunger discharges the fuel through the check valve 45 to the carburetor, returning such portion of the fuel as is in excess of the Vrequirements of the carburetor through the relief valve 49 to the supply tank or, rather, to the inlet side of the check valve. The valve spring and valve stem becoming coated with lubricant which enters through the port 19, this lubricant drains downwardly along the inclined arm 28 into the chamber 32 and stays in the bottom of the chamber around the plunger, thus forming an oil seal for the upper part of the pump. This is not of such great importance while lthe engine is running continuously, but it is very desirable after the engine has been standing sometime to provide a positive seal for the plunger.

Inasmuch as the gasoline dilutes the oil and destroys its efficacy as a seal and a lubricant immediately upon coming in contact with it, it is desirable to prevent the contact of the gasoline with the oil as much as possible. To this end, the size of the check valve 41 and the strength of the spring 42 are so correlated that a considerable amount of suction is required to open the valve. On the other hand, the size of the outlet opening and the Strength of the spring 46 are so correlated that a comparatively low pressure will operate the valve, and the check valve 49 is also arranged to open without any great amount of pressure being exerted, it being understood that the pressure required to serve fuel to the carburetor is very low.

This arrangement of the check valve is such that suction predominates in the cylinder of the pump, that is to say, the depression in the pump cylinder upon the intake stroke of the pump is greater than the compression upon the discharge stroke of the pump. For instance, with atmospheric pressure at fifteen pounds, the pressure in the pump cylinder upon a suction stroke may be about ten or twelve pounds absolute, while the pressure inthe same part of the pump cylinder upon a discharge stroke of the pump will be sixteen or seventeen pounds absolute.

The preponderance of pressure being arranged in this manner, the tendency to'fiow along the walls of the pump cylinder between `the compression chamber and the chamber 32 will favor a flow from the chamber 32 to the compression chamber of the pump. It will be understood that due to the rapid reciprocation of the pump, the liquid which fills the space between the plunger and the walls of the pump cylinder is not changedat each change of pressure in the compression' chamber, the flow being sosl'ow, compared to the course, comparatively small, and the introduction of this oil into the fuel does no harm whatever. Of course, if the tendency to f low was in the opposite direction, the gasohne,

which is of very low viscosity, would quickly Wash out any lubricating oil between the` cylinder and plnger, and a rapid flow of gasoline into the chamber 32 and probably into the'oil sump motor itself `wouldrresult, and this would be-followed by a failure of the pump to prime itself after standing a long time, as the gasoline would all drain outof the pump, or evaporate, and permit air to break the seal of the pump. Gasoline is also a poor lubricant, and a great deal of wear on the parts of the epump would soon result. The comparatively viscuous oil iows through the crevice between plunger and pistn at a very slow rate compared to the rate of flow of gasoline through the same crevice, and, ac cordingly, the arrangement to provide a flow of oil through the pump instead of gasoline is very advantageous.

I claim:

1. In an internal combustion engine, a

' valve .operating chamber,.a coverfor sald chamber, an opening in said cover, a plunger type fuel pump mounted on said cover adj acent said opening, a downwardly extending operating arm arranged to be operated by a part in said valve operating chamber, said arm extending outwardly and downwardly to operate the plunger of said pump whereby lubricant from said valve operating chamber will be turned toward the pump, and a catch pocket or well surrounding said plungerandj maintaining lubricant incontact with the plunger by gravity.`

2. In an internal combustion engine, a fuel pump, a plunger for said pump, an open well surrounding the plunger of said pump, substantially atmospheric pressure being maintained in said well at alltimes and means operated by the engine for supplying lubricant to said well, said pump beingconstructed and. arranged to maintain an average pressure below atmospheric in the cylinder thereof, whereby the suction in said pump will tend to draw said lubricant from said well into said pump.

3. A pump having a vertically disposed plunger, a well surrounding saidplunger at a point spaced from thed lower end thereof,

means for supplying ay sealing Huid to said well,said pump being so constructed and ar; ranged that suction rather than pressure will predominate in the compression chamber of the pump whereby the sealing fluid will tend y pump, and the parts of the pump subject to friction being vmounted below said connection whereby lubricant may drain from said connection to said parts.

5. In a fuel pump, a reciprocating plunger, a cylinder for said plunger, said plunger and cylinder being of comparatively great length and having a small crevice or operating clearance therebetween, a pumping chamber at one end of the cylinder into and out of which a fuel of comparatively low viscosity is pumped, lmeans for maintaining an average pressure in said pumping chamber below that of the atmosphere, a sealingchamber at the other end yof said plunger adapted to contain a sealing fluid, the length of said cylinder and plunger being so great that the interchange of sealing fluid and fuel through the vcrevice between the plunger and cylinder will 7. In a fuel pump, a cylinder, a reciprocat- 1 ing plunger in sai-d cylinder, a sealing chamber at one end of the cylinder adapted to contain a sealing and lubricating fluid, a pumping chamber at the opposite end of the cylinder for pumping a fuel ofcomparatively low viscosity, a plurality of longitudinally spaced chambers formed in the cylinder between the pumping chamber and the-sealing chamber in which fluid from the sealing chamber and the pumping chamber may mix whereby the interchange of iiuids between the opposite ends of the cylinder is retarded.

8. In a pump, a cylinder, a plunger in said cylinder,a pumping chamber in said cylinder at one end of the taining'a sealing and lubricating liquid surrounding said plunger and spaced from said pumping chamber, vand a mixing chamber surrounding said plunger between said pumping chamber and said sealing chamber, said plunger, a chamber conl mixing chamber being sealed from both said pumping chamber and said sealng chamber, except for the opertng clearance between the plunger and the walls of the cylinder.

9. In a fuel pump, a cylinder having a reciprocating plunger therein, an inlet check valve for said cylinder, a comparatively Strong spring for seating said check Valve, an outlet check valve for said cylinder, and a comparatively Weak spring for seating said outlet check valve. Y

10. In a fuel pump, an inlet check valve, and an outlet check valve, said vaves being so constructed and arranged that the inlet check valve requires a greater pressure difference to open it than does the outletcheck valve.

11. In a fuel pump, a cylinder having a reciprocating plunger therein, a sealing chamber at the upper end of the cylinder containing a sealing Huid, a pumpingchamber at the lower end of the cylinder, an inlet check valve, and an outlet check valve for said chamber, said outlet check valve operating with a lower pressure difference than said inlet check valve whereby a flow of sealing fluid toward the pump and chamber is induced.

GEORGE R. ERICSON.

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