US2957423A - Pumps - Google Patents

Description

Oct. 25, 1960 U M 2,957,423

PUMPS Filed June 1955 3 Sheets-Sheet 1 Q-v ELM IQA P. AUDEMAR Oct. 25, 1960 PUMPS 3 Sheets-Sheet 2 Filed June 27. 1955 AW 8 0m United States Patent Ofiice Patented Oct. 25, 1960 PUMPS Pierre Andemar, Mulhouse, Haut-Rhin, France, assignor to Societe Alsacienne de Constructions Mecaniques, 'Mulhouse, Haut-Rhin, France Filed June 27, 1955, Ser. No. 518,276

Claims priority, application France Mar. 15, 1955 1 Claim. (Cl. 103-84) This invention relates to improvements in pumps as well as in pumping units.

Up to now, the so-called viscosity pumps i.e. those pumps wherein a liquid is transferred from an inlet to an outlet by adhering to the surface of a rotor rotating in a casing with a narrow annular or screw-shaped gap therebetween, have been so driven that the said rotation takes place at a comparatively low circumferential speed (usually of about five meters per second).

Now, the applicant has found that by operating such pumps at a far higher circumferential speed (at least equal to meters per second), there are obtained surprising results, which cannot be explained by the conventional theory of viscosity.

As a matter of fact, if a set of curves of the output pressure versus the circumferential speed of relative displacement between the two surfaces are plotted (see Figure 3),

A more particular object of the invention is to design the above mentioned means in such a manner that the said relative speed be higher than 20 meters per second. In the vicinity of this last speed, the curves of pressure versus linear speed offer a particularly interesting utilization zone.

A still more particular object of the invention is to drive the pump with a linear speed of more than 40 meters per second, which is the value above which the pressure vbea screw pump of the type described comprising one or more peripheral grooves provided in the rotor and/or in the fixed casing of the pump, the number of the said grooves being, if desired, comparatively high without resulting in a prohibitive increase in the pump size, since each pump stage comprised between two adjacent grooves (or between the inlet of the pump and the first groove or again between the last groove and the outlet of the pump) may compnise but a reduced length of thread- The invention may be used with a particular efiiciency in high speed rotary machines, wherein, heretofore, the lubrication of the shafts or any other operation having for its purpose to sustain the speed of the machine, is usually ensured by gear pumps, centrifugal pumps etc., which, since they operate at a speed which is far lower than that of the relevant shaft, must be driven from the comessubstantially proportional to the square of the linear speed.

Now, the applicant has found that from. a speed of 10 meters per second, the results obtained are but slightly influenced by the length of the active surfaces in the direction of their relative displacement. In particular, in the case of a screw pump, provided that it .is driven at a high speed as mentioned above, it becomes possible to materially reduce the number of turns, (it is even possible to use but one turn or only a portion of one turn) without important perturbation in the above mentioned results (see again Figure 3, wherein the dotted curves relate to a l5-turn pump while the full line curves show the operation of a one-turn pump, the output rate of discharge being designated by Q on each curve).

On the other hand, when one or more quiescent water zones are interposed in the path of the liquid, between the inlet and the outlet of the pump, the above mentioned results are further considerably improved. The quiescent water zones referred to are zones wherein the water is not in proper circulation.

It is therefore another object of the invention to provide latter through suitable reducing gears. With a pumping unit according to the invention, owing to the very fact that thelpump performance increases with its speed, it becomes possible to drive the pump directly from the relevant shaft without interposing any reducing means, which obviously results in limiting the size, the complexity and the cost of the whole assembly.

Still another object of the invention is, therefore, to provide a power plant comprising, in combination, a machine having a shaft rotating at a high speed and a pump, as defined above, driven directly, that is, without any reducing gear, from the said shaft, the said pump being adapted to sustain the rotational speed of said shaft, for example, by ensuring its lubrication.

A more particular object of the invention is to provide a jet engine assembly, wherein the shaft of the engine drives directly, that is, without any reducing gear, a pump according to the invention ensuring the lubrication of the said shaft and/or feeding the said engine with liquid fuel or combustive.

Other objects and advantages of the invention will be apparent from the following detailed description, together with the accompanying drawings, submitted for purposes of illustration only and not intended to define the scope of the invention, reference being had for that purpose to the appended claims.

In the drawings:

Figure 1 is a longitudinal sectional view of an embodiment of a pump according to the invention.

Figure 2 is an axial sectional view of an alternative construction of a detail of the pump shown in Figure 1.

Figure 3 shows a set of curves giving the value of the output pressure of the pump as a function of the peripheral speed of its rotor for various rates of discharge.

Figure 4 is a longitudinal sectional view of a multiple pumping unit consisting of three pump stages similar to that shown in Figure 1.

Figure 4a is a cross-sectional view taken along line 4a of Figure 4.

' Figure 5 is a view similar to Figure 4 showing an alter native embodiment comprising only two pump stages.

Figure 6 is a cross-sectional view along line 6-6 of Figure 5.

Figure 7 is an elevational view of a power plant comprising a pump according to the invention associated with an air compressor.

Figure 8 is a front view showing a pump according to the invention driven by a turbine.

Figure 9 is a diagrammatical view of a similar pump mounted on a jet engine fed with fuel by means of the said pump.

Referring first to Figure 1, there is shown a pump, the casing of which is constituted by a cylindrical body- 1 in the bore 2 of which is rotativelyfitted a rotor 3 provided with a square screw thread 4 along a length substantially equal to that of the bore 2.

The rotor 3 is provided with two journals 5 and 6 mounted in bearings 7 and 8 forcedly fitted in the extreme parts 11 and 12 of the casing.

The said casing parts 11 and 12 have a cylindrical outer shape. They are housed in the bore 13 of an outer mantle 14. The bearing 11 is provided with an abutment 15 cooperating with a shoulder of the bore 13. On the ends of the mantle 14 are fixedly secured two flanges 16 and 17, for example, by means of screws (only shown in the drawing in the shape of their axes 18).

A number of screws, preferably equally spaced, one of which is shown at 21, have their inner end bearing on the outer face of the bearing 12. The said screws have for their function to clamp against the shouldering 15 of the body 14, the stack assembly comprising the three parts 11, 1 and 12.

Both journals 5 and 6 are provided with cylindrical extensions 24 and 25, so that the rotor 3 of the pump, both journals 5 and 6 and both extensions 24 and 25 constitute one single shaft passing through the whole pump assembly. A disk-shaped annular member 22 mounted on the extension 25 so as to rotate therewith acts as an axial abutment for said journal 6.

The lubrication of the bearings 7 and 8 is eiiected through greasing holes 26, 27 shown in dotted line, drilled through the casing parts 11 and 12 as well as through the mantle 14. The said holes 26 and 27 open in annular grooves 28 provided for this purpose in the bearings 7 and 8. The pump casing 1 is provided with two chambers 31, 32 respectively communicating through ports 33, 34 with an outlet 35 and an inlet 36 preferably threaded innerly to receive suitable pipe fittings. A frustro-conical portion 37 of the bearing 11 extends in the iniet compartment 32. The inner end of the said frustro-conical portion extends in the near vicinity of the adjacent end of the rotor 3; it has for its purpose to offer, in this region, a stationary surface for a function described hereinafter.

The oil used for lubricating the bearings 7 and 8 escapes through two holes 38 and 39 provided in the wall of the mantle 14. Another threaded hole provided with a plug 41 is also drilled through the upper portion of the casing 13 and mantle 14. The said hole may be used, if required, for cleaning and/or priming the pump.

The above described pump operates as follows:

When the rotor 3 is driven at a high speed, the liquid, such as oil, admitted through the inlet 36 passes through the ports 34 into the inlet chamber 32 where it impinges upon the frustro-conical member 37. Thus, it does not rotate with the journal 5 from which it remains separated. The screw thread 4 displaces the liquid along the wall of the bore 2 of the pump casing 1 to force it under pressure into the outlet chamber 31 from which it is discharged out through the outlet 35. The lubrication of the bearings 7 and 8 of the pump may be ensured by a portion of the oil discharged by this pump.

In Figure 2 is shown a modification of the above described embodiment, only diifering therefrom in that the rotor 44 of the pump is absolutely smooth while a helical groove 45 is provided in the wall of the bore 2 of the pump casing 1. All other details of the pump are similar to those of the previously described embodiment, and furthermore, in both embodiments, the pump operates in the same manner.

In Figure 4, is diagrammatically shown an alternative embodiment of the pump according to the invention adapted to generate a far higher output pressure. In this embodiment, there are provided, on the shaft 51, a number (three in the example shown) of rotors 52 similar to the rotor 3 of the embodiment of Figure 1. Each of said rotors works in a corresponding section of the bore 2 of the pump, these difierent parts of the bore being separated from each other by grooves53, each of which acts as an outlet chamber for one of the rotors,- and as an inlet chamber for the following one. In one of the grooves 53, is shown as an alternative feature, a blade 121 integral with a plug 120 and so oriented as to oppose the rotation of the liquid in said compartment. The blade 121 tends to guide the liquid in groove 53 in a substantially straight stream.

The shaft 51 is journalled in two rings 54 and 55. The ring 54 is forcedly secured in a flange 56 attached to the body 57 of the pump, for example, by means of two screws diagrammatically shown in the shape of their axis 58, while the ring is forcedly secured in a corresponding bore of the pump body 57. As in the embodiment of Figure 1, the flange 56 comprises a hub 59 extending in the inlet chamber 61. In the embodiment, the outer surface of the hub 59 is cylindrical. A threaded hole 62 communicates with the inlet chamber 61 and permits fitting a suitable suction pipe. At the opposite end of the pump casing is provided an outlet chamber 63 communicating with outside through another threaded hole 64. Each rotor 52 increases the pressure of the fluid by a certain amount each time the said fluid passes from one compartment to the following one to be discharged finally, through the outlet 64, under a pressure that may be comparatively high if a suficiently great number of rotors 52 are provided on the pump spindle.

It is to be noted that the fluid entering the inlet chamber 61 first impinges upon the stationary hub 59, which facilitates the action of the screw thread adjacent to said hub. On the contrary, the fluid discharged out of the first stage into the groove 53 is at least partly in direct contact with the spindle of the rotor, so that it may be driven by the same, thus acquiring a certain objectionable peripheral speed hindering the axial action of the following screw thread of the rotors 52. This is the reason why, in the alternative embodiment shown in Figure 5, the groove 53 has been provided with a stationary partition 65 in which are drilled channels 66 setting both portions of the said groove 53 into communication with each other. In this embodiment, the pump casing is constituted by several parts (two in the example shown wherein the pump comprises two stages and two rotors 71). Figure 6 shows the particular shape of the partition I 65 as well as the circular shape of the ducts 66; the partition 65 proper is made of two pieces, the assembling surface of which extends in a diametral plane to permit mounting of the assembly, the same comprising one single shaft 72 passing throughout the pump. The various members of the pump casing are assembled on the partition 65 by means of bolts passing through holes 74 (Figure 6).

Otherwise, the design and operation are similar to those of the embodiment shown in Figure 4, the only difference being that the circumferential speed of the oil expelled out of the first stage of the pump is substantially cancelled by the circulation of the said fiuid through the stationary ducts 66. This arrangement ensures an eflicient operation of the screw thread of the second rotor 71.

'It is clear that a greater number of rotors may be provided on the shaft of the pump with a pump casing having a number of parts corresponding to the said number of rotors.

In Figure 7 is shown an illustrative application of a pump according to the invention. The casing of this pump is shown at 81 and is carried by a base 82. The rotor 83 is coupled with the output shaft 84 of a speed multiplying gear 85 of any suitable conventional type, the input shaft 86 of which is rotated from the driving shaft 87 of a suitable prime mover, such as an electric motor indicated at 88. The rotor 83 of the pump is further coupled with the rotor 91 of a compressor, the stator 92 of which is supported by a base 93. It may be seen, in this illustration, that the existing plant provided for driving the compressor 91 may be used at the same time for rotating the high speed pump 83 according to fl invention. The discharge pipe 94 of the pump may be interconnected with the various bearings of the plant for lubrication purposes.

In Figure 8, is shown another example of a plant comprising a pump according to the invention, the rotor 83 of which is rotated by a turbine 97 further rotating a compressor 97a. The oil is sucked by the pump 83 from a tank or reservoir 98. It is used in this example solely for lubricating the turbine 97 by means of a suitable duct 101 interconnected with the discharge pipe 102 of the pump while ducts 103 are provided to return the oil into the tank 98. It is to be noted that this plant design is extremely simple. The pump rotor is directly keyed on the common shaft of the turbine and compressor; nevertheless, the said pump is capable of supplying a greasing pressure of any desired value.

Finally, there is shown in Figure 9 another example of an alternative use of a pump according to the invention wherein the rotor 83 of the said pump is directly keyed on a shaft 105 on which are further mounted the rotor 106 of a jet engine and the rotor 107 of its compressor. The pump 83 is used in this example for directly injecting fuel through a feeding pipe 108 into the injectors 109, disposed within the compression chambers 111 of the jet engine. 'Due to the high speed of the jet engine rotors as well as due to the comparatively important pressures at which the fuel is injected into the combustion chamber of the said engines, the pump according to the invention finds there a particularly interesting application since it is perfectly adapted to high speeds of rotation as well as to generation of high pressures.

While the invention has been described with particular reference to a preferred embodiment, it is not intended to limit the scope of the invention to the embodiment illustrated, nor otherwise than the terms of the subioined claims.

What is claimed is:

In a rotary pump comprising a stationary cylinder provided with axially spaced inlet and outlet ports and a rotatable body of circular section mounted in said cylinder to extend between said inlet and outlet ports, the peripheral surface of said body having an annular groove, the peripheral surface of said body having a first helical groove describing substantially one turn to form a first short helical passage communicating at one end with said inlet port and at the other end with said annular groove, the peripheral surface of said body also having a second helical groove describing substantially one turn to form a second short helical passage communicating at one end with said annular groove and at the other end with said outlet port, said helical grooves being each of such shallow depth as to provide a viscose contact surface, and said annular groove being of greater depth than said helical groove, blade means secured to said cylinder and extending into said annular groove to oppose rotation of liquid therein, and means for rotating said body to thereby displace liquid from said inlet port through said first passage to said annular groove and from the latter through said second passage to said outlet port by viscosity action.

References Cited in the file of this patent UNITED STATES PATENTS 1,448,079 Noeggerath Mar. 13, 1923 1,665,931 Noeggerath Apr. 10, 1928 2,313,909 Arnold Mar. 16, 1943 2,351,431 Irons June 13, 1944 2,402,467 Thompson June 18, 1946 2,576,352 Neal Nov. 27, 1951 FOREIGN PATENTS 97,928 Switzerland Feb. 16, 1923 173,043 Great Britain Dec. 16, 1921 354,825 Germany June 15, 1922 402,961 Italy Mar. 31, 1943

Images