US1572045A

US1572045A - Philip lane scott

Info

Publication number: US1572045A
Authority: US
Publication date: 1926-02-09
Anticipated expiration: 1943-02-09

Description

P. 1 SCOTT PUMP Filed Dec. 15, 1919 Feb. 9 1926.

PHIL/P L. SCOTT ATTORNEYS IN VENTOR Patented Feb. 9, 1926.

UNITED STATES 1,572,045 1-'A'11=.'NT- oFFicE.

PHILIP LANE SCOTT, OF THREE OAKS, MICHIGAN, ASSIGNOB, TO -SUPEB DIESEL TRACTOR CORPORATION, OF LA PORTE, INDIANA, A CORPORATION OF-NEW YORK.

PUMP.

Application filed December 15, 1919. Serial No. 344,883.

To all whom, t may cof/wcm:

Be it known that I, PHILIP L. Scorr, a citizen of the' United States, residing at Three Oaks, in the county of Berrien and State of Michigan, have invented a certain new and usefuljlmprovement in Pumps, of which the following is a specification.

My invention relates to improvements in oil pump constructions and the like and has for one object to provide a pump in which all working parts are properly lubricated and in which leakage is prevented.

Another object is to provide a pump wherein the clearances will be sufficiently minute to permit pumping to be done by piston or plunger Without any packing and without disastrous leakage.

Experience shows that when the necessary minute clearances are employed, you must use certain materials of which cast iron `is one which takes a fine finish but which will not bind or grip the plunger when distorted as the parts inevitably are by heating as the work progresses. Such materials are so coarse that While no leakage takes place around the plunger, undesirable leakage takes place in the material and therefore, some kind of jacket impervious to liquids must be used to surround and pack the cylinder lining.

It may be said in this connection that one reason why cast iron is satisfactory for this purpose is that even though the soft iron warps and develops in pumps lumps and distortions which engage the plunger, these irregularities are immediately worn down without sticking. If bronze were used, we

would have binding of the piston as soon asv any appreciable distortion has taken place. Other objects will appear from time to time in the specification.

My pump, in the form here illustrated, is particularly designed for use with direct injection hydrocarbon internal combustion engines, where high pressures are used. It may, however, be adapted to a 'variety of other uses, for example wherever a pump is required. One form is illustra-ted in sec-l tion in the accompanying figure, wherein- A is a jacket impervious to oil,` and in the form here illustrated, is made of steel.

Be is an inner liner of such material that the oil may penetrate in it and through it, and which is of Sucha character that it fulfills the requirements above pointed out inconnection with the close clearances and fits required. In this case, it is made of cast iron. B1 is a bore in the linerwB and enlarged at B2 to provide an oil pocket or chamber. B3 is a bore in the side of the liner B and extending through the jacket A. B5 is another bore in the liner B, extending through the jacket A.

O is an outlet connection, screwethreaded into the bore B5 of the jacket A. It has the central bore O1 which is enlarged at C2 and provided with a beveled valve seat C3 upon which the valve C4 is adapted to be seated by the spring C5. C is a packing ring held against the sleeve C7 in the bore B5 which sleeve is beveled at C8 to receive the spring O5 and has the bore C in which the valve C10 is located. The valve C10 is adapted to be seated on the beveled valve seat C by the spring C12. This double valve arrangement constitutes the inlet side of the pump.

D is a discharge connection, screw-threaded into the jacket A in the bore B". It has the central bore D1 which terminates at one end in the beveled face D2 against which the spring D3 abuts. D4 is a packing. D5 is a valve sleeve having the pocket D in which is the beveled valve seat D7. D1g is a valve adapted to be seated on the valve seat by the spring D3. D9 is a narrowed bore in the valve sleeve in which the valve Ds is positioned. D1o are vanes on the valve adapted to contact the sides of the bore and to cause the proper seating and alignment of the valve. This type of valve which 'is used throughout, has been chosen because of the relatively free passage which it allows for the oil the moment the valve head has become unseated.

E is a plunger having the enlarged head E1. E2 is a collar secured on the head. E3 is a spring abutting at one end against the liner B and at the other against the collar E2.

The pump may be driven by any suitable means such as a cam or rocker arm, not here shown, forming no part of this invention.

The liner of the pump -which is made of cast iron is permeable and the oil from the pump chamber penetrates the pores of the iron and under pressure will Work entirely through the liner and will saturate it from end to end. There would be substantial loss of oil if we did not provide some additional protection against 1t. 'This is provided in ythe steel Jacket surrounding the cast iron liner. The jacket is not permeable and the oil working through the liner comes to the jacket and goes no further.

'lhere is the additional feature of lubrication due to the porous quality of the iron. It'has been found in practice that the oil will workf through the iron and back along the piston through its entire length. This results in a film of oil entirely surrounding the piston throughout its length and thoroughly lubricating it without the medium of any additional channels or passages.

In my apparatus, I do not know exactly what the clearances are between the plunger and the plunger seat. They range probably somewhere in the neighborhood of a. tenthousandth of an inch. There-ason why I do not known what the clearances are is because the parts are made originally with practically no clearance except that necessary to make it possible to force the plunger into the seat with a pressure of from l5 lbs. up, the plunger and seat being lubricated and then reciprocated with reference one to the other and thus being lapped in together with an oil tight working fit without the use of any abrasive material.

While my pump might be used in a variety of connections it is intended particularly for use with extremely high pressures, that is with pressures of many thousand pounds per square inch and with an extremely minute clearance between the pump plunger and the bore within which it reciprocates. This clearance is so small as to constitute practically a capillary passage, and itis so small that the resistance to molecular separation, that is the surface tension of the oil which it is intended normally to pump, tends very strongly to prevent passage of the oil between the plunger and the wall of the bore. Reciprocation of the plunger, however, positively moves some of the oil between the bore and the plunger and the capillary action of the space about the plunger serves also to draw oil between the two parts.

The use and operation of my invention are as follows When the pistonv is drawn out by the spring, a suction is produced and the two valves on the suction side are opened by it against the pressure of their springs. By this means oil is drawn into the pumping chamber. When the piston is forced back in opposition to the spring, suction no longer exists within the pump and the inlet valves are seated by their respective springs. As the movement of the piston continues, pressure is created and the discharge valve is unseated by it, and the liquid is forced out through the discharge connection.

I find that the close fits provided make leakage along the plunger practically impossible and it is a fact that a pump handling upwards of 400 cubic inches of oil per hour at pressures ranging from 300 to 800() lbs. per square inch, willnot leak more than a few drops of oil past the plunger during an hour period. In fact there is less leakage than on any stuiing box that could be designed for use with apparatuses such as that with which my pump is associated.

It will be evident that while I have shown in my drawingsv an operative device, still many changes might be made in size, shape and arrangement of parts without departing materially from the spirit of my invention, and I wish, therefore, that my drawings be regarded as in a sense diagrammatic.

It will be understood that this invention is particularly intended for the handling of perhaps relatively light and fluid oils where relatively high velocities are used, and it finds perhaps its greatest exemplification in feeding such oil as kerosene or perhaps even gasoline through the spray nozzle to be used with the Diesel or similar types of engine.

It is an interesting fact in connection with this particular arrangement of pump and bearing surface, thatA when the pump is properly made, we have a pump in which the plunger is actually freer to reciprocate than it would be if the normal type of stuffing box were used and this characteristic is one of the essential or at least exceedingly important characteristics because it makes the pump smooth and responsive in'its action.

When the plunger and the bearings are fitted as I have above suggested, their relation is vsuch that the plunger will be suspended or centered in the seat by a very thin film of oil and this film is preferably so thin that the surface tension of the oil is sufiicient to resist the shearing action resulant from the movement of the plunger with respect to the seat even though the pressures are very great, and thus gives us a continuous oil film so that there is a negligible frictional resistance to the movement of the plunger and it is this surface tension also which probably prevents, or is largely active in preventing any leakage between the plunger and the seat. This is sharply contrasted with any arrangement where a stuffing box is used because the stufiing box has for its characteristic that it tends to break the oil film thus increasing the re sistance to the movement of the plunger and also doing away with any benefit which may be obtained from the surface tension resisting the leakage.

Preferably the piston is made of harder material than the cylinder within which it Works though it is conceivable, and under have the cylinder made of 'harder material y and the piston of the softer material.

One explanation for the fact that my pump can be made to operate without appreciable leakage is that the clearance between pump lunger and pump cylinder is so slight that ln the oil film between the two opposed surfaces the effect of eddy currents and the like is reduced to a negligible minimum and the friction of the oil against the metal surfaces is so great in proportion to the thickness of the 011 film that iow is resisted by the res istance of the oil itself to molecular separation.

When a conventional type of pump cylinder and plunger is used and the parts are fitted in the machine shop they are ordinarily fitted cold and the clearance is measured in thousandths of an inch. My umps are such that while their fit may not e as satisfactory as it might be when cold they fit when warm or when at running temperature so closely that clearances are measured in not thousandths but ten-thousandths of an inch and it is this ver minute clearance which enables the skin riction and the resistance to molecular separation to hold the fluid being pumped and prevent appreciable leakage even at pressures up to ten thousand pounds to the square inch and more.v

There is an essential relation between the use of materials of varying hardness and the very close clearances used because experience has shown that if for instance a steel cylinder and steel plunger are used with clearances small enough to enable this molecular resistance to prevent leakage, the pump and plunger will almost invariably seize as soon as they heat up to a working pressure and no matter how hard the two materials are we do not ordinarily get a satisfactory operation with two materials of the same hardness as when one is harder than the other.

I claim:

1. A pump comprising a cylinder, a plunger mounted for-reciprocation therein, one o f them being of softer material than the other, the clearance between them being such that travel of a liquid film between them is eifectually prevented by the resistance to molecular separation of the oil film.

2. A pump comprising a cylinder of relatively soft material, a plunger of relatively hard material mounted for reciprocation therein, the clearance between them being such that travel of a liquid film between them is e'ectually prevented by the resistance to molecular separation of the oil film.

3. A pump comprising a plunger, a cylinder therefor, there being such a close fit between the cylinder and the plunger that the passage of oil between them is effectively prevented, and an impervious jacket surrounding the cylinder.

4: A pump comprising 4a plunger, and a cylinder therefor,'one of them being of relatively softer material than the other, there being such a close fit between them that pas-- sage of oil between them is effectively prevented, and an impervious jacket surrounding the cylinder.

5. A pulnp comprising a plunger of relatively hard material, a cylinder of relativer" ly soft material, there being such a close fit between them that passage of oil between them is effectively prevented, and an imj pervious jacket surrounding the cylinder.

6. A pump comprising a plunger, a cylinder therefor, there being such a close fit between the cylinder and the plunger that the passage of oil between them is effectively prevented, and an impervious jacket surrounding the cylinder and extending on 'both sides far beyond the limit of the excursion of the working end of the plunger.

7. A pump comprising a plunger and a cylinder therefor, one of them being of rela.- tively softer materialv than the other, there being such a close fit between them that passage of oil between them is effectively prevented, and an impervious jacket surrounding the cylinder and extending on both sides far beyond the limit of the excursion of the working end of the plunger.

8. A pump comprising a plunger of relatively hard material, a cylinder of relatively soft material, there being such a close fit between them that passage of oil between them is effectively prevented, and an impervious jacket surrounding the seat and extending on both sides far beyond' the limit of the excursion of the working end of the plunger 9. A pump comprising an apertured cylinder block, a pressure chamber therein communicating with the aperture, a plunger mounted for reciprocation in the aperture toward and from the pressure chamber, the substance of which the cylinder block is made being pervious to liquid, and an impervious jacket for the block.

10. A pump comprising an apertured cylinder block. a pressure chamber therein communicating with the aperture, a plunger mounted for reciprocation in the` aperture toward and from the pressure chamber, the

substance of which the cylinder block is being such that leakage from the chamber along the plunger is el'eetively prevented.

12. A pump comprising a plunger and a wat therefor, one of them belng of relatively softer material than the other, there being such a close fit between them that passage of oil between them is effectively prevented by the resistance of the oil to shearing, characteristic of the property of viscosity of the liquid, the plunger being free to reciprocate without appreciable frictional interference to its action.

13. A pump comprising a plunger of relatively hard material, a cylinder of relatively soft material, there being such a close fit between them that passage of oil between them is e'ectively prevented by the resistance to molecular' separation `of the oil film, the plunger being free to .reciprocate without appreciable frictional mterference to its action.

14. A pump comprising a plunger, a cylinder therefor, there being such a close fit between the cylinder and the plunger that the passage of oil between them is ef-v fectively prevented, and an impervious jacket surrounding the cylinder, the plunger being free to reciprocate without appreciable frictional interference to its action.

15. A pump comprising a plunger and a cylinder therefor, one of them being of relatively softer material than the other, there being such a close fit between them that passage of oil between them is effectively prevented, by the resistance to molecular separation of the oil film, the plunger being suspended within its cylinder by a continuous oil ilm interposed between the plunger and the cylinder throughout their entire opposing areas.V

16. A pump comprising a lunger of relatively hard material, a eylinc er'of relatively soft material, there being such a close fit between them that passage of o l between them is effectively prevented, by the resistance to molecular separation vof' the oil film the plunger being suspended within its cyllnder by a continuous oil film interposed between the plunger and the cylinder throughout their entire opposing areas.

17. A pump comprising a plunger, a cylinder therefor, there being such a close fit between the cylinder and the plunger that the passage of oil between them is effectively prevented, and an impervious jacket surrounding the cylinder, the plunger being suspended within its cylinder by a continuous oil film interposed between the plunger and the cylinder throughout their entire opposing areas.

18. A pump comprising a cylinder, a plunger mounted for reciprocation therein, one of them being of softer material than the other, the clearance between them being such that travel of a liquid ilm between them is electually prevented by the resistance of molecular separation of the oil lm at extremely high pressures.

19. A pump comprising a cylinder, a plunger mounted for reeiprocation therein, one of them being of softer material than the other, the clearance between them being such that travel of a liquid film between them is e'ectally prevented by the resistance of molecular separation of the oil film at pressure of at least three thousand pounds per square inch. y

In testimony whereof, I aiiixA my signature this eighth day of December, 1919.

PHILIP LANE SCOTT.