US3664461A

US3664461A - Oil pump for a motor compressor

Info

Publication number: US3664461A
Application number: US129994A
Authority: US
Inventors: Hans Ulrik Leffers; Bendt Wegge Romer; Knud Vagan Valbjorn
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 1971-03-31
Filing date: 1971-03-31
Publication date: 1972-05-23
Anticipated expiration: 1989-05-23

Abstract

The invention relates to a lubricating system for a motor compressor assembly. The assembly has an oil sump and the motor compressor unit has vertically extending shaft means with a central lubricating bore, the lower part of the shaft means being disposed in the sump with the mouth of the bore being in fluid communication with the lubricating oil in the sump. The mouth of the shaft bore is provided with a propeller to effect an increased rate of lubricating oil delivery.

Description

United States Patent Leffers et al. 1 May 23, 1972 OIL PUMP FOR A MOTOR [56] References Cited COMPRESSOR UNITED STATES PATENTS [72] Inventors: Hans Ulrik Leffers; Bendt Wegge Romer, 2,835,437 5/1958 Boynton ..184/6.l6 both of Augustenborg; Knud vagan 2,809,872 10/1957 Wamer.... jom, Nordborg of Denmark 2,1 l Heller l 9 3,410,478 11/1968 Geisenhaver ..417/366 [73] Ass1gnee: Danfoss A/S, Nordborg, Denmark F REI PA R L1 [22] Filed: Mar. 31, 1971 o GN TENTS 0 App CATIONS 1,354,164 1/1964 France [21] Appl. No.: 129,994

Primary Examiner-Manuel A. Antonakas Related Application Data Attorney-Wayne B. Easton [63] Continuation of Ser. No. 836,118, June 24, 1969,

abandoned. [5 7] ABSTRACT The invention relatesto a lubricating system for a motor com- [52] U.S. Cl ..184/6.l6, 184/6. 1 8, 308/ l 34. l ressmassembly, The, assembly has an oil sump and the motor 415/88 compressor unit has vertically extending shaft means with a [51] Int. Cl ..F16n 7/18 n r l lubricating bore, h lower part f the shaft means 58 Field 0! Search 184/616, 6.18; 308/ 1 34. 1; being disposed in the p with the mouth of the bore being in 45/88 fluid communication with the lubricating oil in the sump. The

mouth of the shaft bore is provided with a propeller to effect an increased rate of lubricating oil delivery.

1 Claim, 3 Drawing Figures OIL PUMPFORA MOTOR COMPRESSOR This application is a continuation of Ser. No. 836,1 l8, filed June 24, 1969 and now'abandoned.

The invention relates to an oil pump for a motor compressor having a. vertical motor-shaft, through the bore of which oil is delivered to the points where it is to be used, and the lower end of which extendsintoan oil sump and is provided with a solidly built-in insert for increasing the delivery of oil.

Such oil-pumps are used for example for lubricating and cooling encased motor compressors for small refrigerating machines. In a known oil-pump, the lower. end of the shaft, extending-into the oil sump, consists of a frusto-conical hollow portion. The oil is entrained through friction by'the wall of the cone and is carried upwards long the inside wall of the cone by centrifugal force. A body of oil, defined by a'paraboloid, is then formed in the interior of theshaft, and oil from this body is passed to the points where it is to be used with thehelp of further delivery means, or without such help if the'pressurelevel of the oil is itself sufficient. In this connection, it is also known to fit an axially parallel sheet-metal element in the lower end of the hollow cone, the function of which element is to set the oil in rotation more rapidly and thereby to increase the pressure-level that can be produced with the help of the hollow cone. Here, a certain limit for pressure-level or quantity of oil delivered cannot be exceeded, since the geometrical dimensions of thehollowcone are fixed to a large extent, in particular, the upper cross-section by the cross-section of the shaft, and the lower cross-section by a minimum inlet orifice.

The object of the invention is to achieve a'higher pressurelevel and/or a greater delivery quantity in an oil-pump of the originally described kind.

According to the invention this object is achieved by the insert taking the form of a propeller having a vertically disposed axis.

This sheet-metal propeller insert imparts drive to the oil not only in the circumferential direction but in the axial direction too. The circumferential movement can, in conjunction witha hollow cone, be utilized to increase the centrifugal'pumping action, and the axial drive contributes directly to increasing the pressure. Since the shaft rotates at a high speed, e.g. at 3,000 r.p.m., the forces applied to the oil are considerable.

In a further form of the invention, the shaft can be fonned atthe bottom as a cylindrical tube which, at its lower end, ac-

commodates the propeller-like insert of roughly the same diameter. As against the hollow cone, such a tube not only has the advantage of being of simpler shape, but it also has a larger inlet orifice, so that, for a likerate of flow, a larger quantity of oil can enter. The loss in delivery capacity resulting from the non-use of a hollow cone isconsiderably more than compensated by the fact that a propeller having a relatively large diameter can be used. This results in a-pump that delivers a large quantity of oil and operates at a high delivery pressure.

A particularly simple construction is obtained if the motorshaft consists of two parts inserted in the bore of the rotor, the upper of which parts carries the crank and the lower one constituting an oil-delivery pipe. In this way, practically the entire cross-section of the bore of the rotor is available for'delivering the oil.

In a further form of the invention, the outside circumference of the tube can have a shoulder which alone, or by means of a disc fitted thereon, forms a stop limiting the extent to which the tube can be pushed into the rotor. This renders assembly easier, since the position of the inserted part is accurately predetermined by this shoulder.

The stop can also lie on the short-circuiting ring of the rotor and can seal off an annular distributing chamber which communicates with the interior of the tube through openings in the tube and from which passages lead to the upper side of the rotor. Because of the high delivery capacity of the oil-pump, a considerable amount of surplus oil is available for cooling the statorwinding. This surplus is passed through the annular distributing chamber and the passages in the rotor, which offer relatively little resistance, and is flung over the stator coil-ends at the upper side of the motor. The remaining stream of oil,

which passes in the interior of thehollowmotor-shaft, is unaffected by this.

The invention will now be described inmore detail by reference to embodiments illustrated in the drawing, wherein:

FIG. 1* shows a longitudinal section through anencased motor compressor incorporatingthe oil-pump of the'invention,

FIG. 2 is a-planview of the propeller-like sheet-metalinsert, and

FIG. 3 shows a portion of a modified form of construction.

A carrier element 2is supported in a case 1 by means of springs, not illustrated. The carrier element supports the stator 3' of an electric motor, incorporates a bearing 4 for the motor crankshaft Sand, together with an extension 6, forms, on the one hand, noise-reducing, chambers 7 and, on the other, a cylinder, not illustrated, the axis of which extends at right-angles to the plane of the drawing. An insert 8 closes the noisereducing chambers7 and formsasecond bearing 9. A backing plate llJand a centrifugingplatel2are fitted at the upper end of the shaft 5 by meansof a screw-bolt 10. At its crank 13, the shaft carries a crank bearing 14, which is linked to the connectingrod of the-piston- The rotor l5' of the motor has an upper short-circuiting ring 16 and a lowershort-circuiting-ring 17'. The stator has upper coil-ends l8 and lower coil-ends 19. The bore 20 of the rotor is shrunk on to the shafts. A cylindrical tube 21 is inserted from below into the bore 20, this tube constituting an extension of the motor-shaft and acting-as the oil-delivery means. The tube has an outer shoulder 22, which carries a disc 23, which bears against the lower short-circuiting ring 17 of the rotor. Precise positioning of the tube 21 when fitted is thus ensured.

Providedat the lower end of the tube 21 is a propeller-like sheet-metal'insert which can be simply pressed into the tube 21; In thepresent embodiment, this insert consists of a sheet-metal disc which contains radial slots 25 at intervals of 90, the parts between the slots being inclined as in a propeller.

Thetube extends into the=oil sump 27. Oil supplied by the propeller 24'risestl1rough-the-interior'28 of the tube and the borer29 of the shaft 5. Runningfrom the bore 29 are a crossbore 30, forlubricating'the-bearing 4, and three parallel bores 31, 32land33 whichzterminate'at the top near the plate 12. A cross-passage-for lubricating thecrank bearing 14 can branch from the bore 31, anda cross-passage for lubricating the bearing 9 branches from the bore 33. Thesurplus oilcomes out at v the top intothe plate lZand is flung on' to the wall of the case l alongwhich itruns back into the sump 27 and is cooled in so doing.

The tube 21 also contains holes 34*opening into an annular distributing chamber 35 which is formed between the tube 21, the rotor 15, the short-circuiting ring- 17 and the disc 23. Passages 36 in the rotor extend upwards from this chamber. Theseterminate in a chamber 37. The'oil delivered to this point is flung outwards by the upper short-circuiting ring 16 and strikes the upper coil-ends='l8-, thereby cooling them. The oilthen flows back into the sump=27l The pipe21 and the propeller-like insert 24' deliver so great a quantity of oil that adequate lubrication takes place, the stator coil ends are cooled and, furthermore, a certain quantity of oil is circulated in such manner that the oil flowing down over the-wall of the case is cooled and the mean oil temperature is thus kept low.

FIG.'3 shows how the tube 21 can alsobe pushed by its shoulder 22 directly'against the lower end-face of the stator 15 was to define the position of the tube. A slight depression of, for example, 0.2 mm, is sufficient for forming the shoulder.

In some cases it is also of advantage for the tube itself to be provided with a fairly thick flange which acts as a stop on the short-circuiting ring 17. The bores 34 can then be contained in this flange and can extend obliquely upwards, so that a still further delivery action is obtained.

We claim:

shaped sheet metal propeller mounted in the mouth of said bore, said propeller having a diameter equal to the diameter of said bore and having a plurality of radially extending vanes separated by radially extending slots with each of said vanes being inclined relative to the axis of said bore.

Claims

1. A motor compressor assembly comprising a housing, a combined motor and compressor unit in said housing, a common frame for said unit, vertical motor and compressor shaft means journalled in said frame, an oil sump in the lower part of said housing, said shaft means having a central lubricating bore in fluid communication with said sump, a generally disk shaped sheet metal propeller mounted in the mouth of said bore, said propeller having a diameter equal to the diameter of said bore and having a plurality of radially extending vanes separated by radially extending slots with each of said vanes being inclined relative to the axis of said bore.