US1946524A - Vacuum pump - Google Patents

Description

Feb. 13, 1934. D. N. cRosTHwAl-r, JR

VACUUM PUMP 3 Sheets-Sheet l Filed May l5. 1931 Feb. 13, 1934. D. N. cRosTHwAlT, JR

VACUUM PUMP Filed May 15, 1931 3 Sheets-Sheet 2 W w 6 W W/ n Feb. 13, 1934. D. N. cRosTHwAlT, JR

VACUUM PUMP Filed May l5, 1931 3 Sheets-Sheet 3 Patented Feb. 13, 1934 UNITE STATES PATENT OFFICE l Laisser.

VACUUM PUMP Application vMay 15, 1931. serial No. 537,634

`15 Claims.

This invention relates to a new and improved vacuum pump of the jet exhauster type, and more particularly to such an exhausting mechanismv embodying a positively vrotated centrifugal impeller for dispersing the motor liquid and irnparting additional energy thereto for increasing the eiciency and exhausting capacity of the Pump.

Brieily described, mechanism is provided whereby the stream or jet of liquid under pressure is projected against a rapidly rotating impeller whereby this stream is dispersed and finely divided and projected outward radially of the impeller by centrifugal force with high velocity through a restricted annular discharge passage. Fluids from the exhauster chamber within which the jet and impeller are positioned are entrained by the jet and by the liquid particles thrown cutwardly through the annular passage and carried away against atmospheric or higher pressure along with the motor liquid. l

The general object of the invention is to provide a new method and apparatus for producing a vacuum, as briefly described hereinabove and disclosed more in detail in the specifications which follow.

Another object is to provide an improved vacuum pump capable of producing a high degree of vacuum without utilizing any heavy rotating parts.

Another object is to provide improved means for atomizing or highly dispersing the uid jet and projecting these fluid particles outwardly at high velocity through a suction space.

Another object is to provide a pump of this type in which it is not necessary to maintain a prime in the air impeller.

Another object is to provide a combined centrifugal pump. jet exhauster, and centrifugal exhauster, embodying a single rotating assembly.

Another object is to provide improved means for automatically adjusting the liquid ow through the outlet passage of the centrifugal exhauster.

(Cl. B30-4.08)

tion of Fig. l showing modifications in the impeller and outlet passage.

Fig. 5 is a partial perspectiveview of one of the annular diiiuser rings which form the outlet passage, of the type disclosed in Fig. 1.

Fig. 6 is a longitudinal vertical section through a simpler form'of the exhausting mechanism, the view being taken substantially on the line 6 8 of Fig. 7.

Fig. 7 is a transverse vertical section taken sub- 06 stantially on the line 7-7 of Fig. 6. i

Fig. 8 is a perspective view of the centrifugal impeller of the form shown in Figs. 6 and 7.

Fig. 9 is a central vertical section through another modification of the exhauster mechanism. m

In order to facilitate the disclosure, the simpler form of the exhausting mechanism shown in Figs. 6, 7 and 8 will first be described. The` exhauster casing comprises two intertting castings 1 and 2 which inclose a central exhausting 'l5 chamber 3 and an outer annular discharge conduit 4 of volute form leading to a discharge outlet 5. The casing section 1 may be formed integrally with a supporting base 6, and is also provided with a bearing '7 for the rotary 8o shaft 8 which projects through casing 1 into the exhauster chamber 3. Any suitable means may be provided for rotating the shaft 8 at relatively high speed. A packing 9 held in place by gland 10 prevents the flow of iiuid around the rotary 85 shaft 8.

The other casing section 2 is formed with an outwardly projecting hollow cylindrical extension l1 to which is bolted a cover plate 12 in which the liquid supply pipe 13 is screwed at 14. 90 The ejector nozzle 15 has an outwardly projecting collar 16 at its inlet end which is clamped between the hub 11 and cover plate 12, the in. ner restricted end 17 of the nozzle being adapted to project a stream of liquid into chamber 3 in 95 line with the axis of rotary shaft 8. The liquid under pressure can be supplied from any suitable source through pipe 13. A pipe 18 communicates with inlet 19 and is connected with the space from which iiuids are to be exhausted.

A pair of annular restricting rings 20 are mounted lwithinthe casing sections 1 and 2 respectively so as to define an annular outlet channel 21 between chamber 3 and discharge conduit 4, this annular channel functioning much the same as the usual delivery tube of a jet exhauster. Each ring 20 is provided with an outward extending cylindrical angevor collar 22 which flts within a corresponding depression in one of the casing members so as to properly center the ring 110 about the axis of shaft 8. The inner surfaces of the rings 20 are curved or bowed inwardly so as to form a converging inlet portion 23 and a diverging outlet portion 24 leading to and from the restricted throat portion of the channel 21. 4

The rotary impeller 25 is keyed as indicated at 26 on the inwardly projecting end portion of shaft 8. This impeller is formed internally with a circular series of substantially radially extending passages 27 separated by webs 28. It will be noted that these webs curve forwardly somewhat in the direction of rotation of the impeller, but the outer end portions of the webs extend substantially radially of shaft 8. The central inner portion of the impeller is formed with an open inlet tube 29 for receiving the liquid jet from nozzle 15, and the inner inlet ends 30 ofthe passages 27 communicate with this inlet tube 29. The inner walls of the impeller curve to a central point extending toward the jet as indicated at 31. As here shown the central point or stud of this curve portion is formed on the inner end of shaft 8. This projecting portion 31 serves to divide the jet and divert and disperse the water into the several passages 27.

In operation, a jet of water under pressure is projected into chamber 3 through the restricted nozzle 17. As this jet travels through chamber 3 into the receiving tube 29 a certain amount of gases or other fluids from chamber 3 will be entrained therewith in the usual manner of jet exhausters. As this stream hits the point or blade 31, the water will be diverted or deected substantially at right angles and dispersed amongst the several passages 27 of the impeller. The Water thus thrown or diverted into the passages 27 has an initial velocity component in a radial direction derived from the force of the original jet, and this velocity is considerably added to by the centrifugal force imparted by the rotary impellerso that the water particles are thrown outwardly at high velocity from the periphery of the impeller into and through the delivery channel or passage 21. By this time the water has been dispersed into a sheet of separated particles each having a high velocity whereby a maximum amount of gases or fluids from the chamber 3 will be entrained therewith and carried through the passage 21 into the discharge passage conduit 4. This discharge conduit 4 is constructed in the usual manner as a volute of increasing cross section in the direction of rotation of the impeller so as to properly receive and accommodate the fixed fluids discharged through channel 21 against atmospheric or higher) pressure, and thence passed outwardly through discharge outlet 5.

As shown in Figs. 6 and 7, a disk or vane 32 is secured about the periphery of impeller 25 and extending into channel 2l. This rotating disk serves to impart additional energy to the fluids discharged outwardly through passage 2l and thus overcomes the opposing pressure against which these fluids are delivered. Suitable ribs or blades could be formed on one or both sides of the vane 32, if desired. Since the use of this disk 32 is optional, it has not been illustrated in the separate view of the impeller 25 shown in Fig. 8.

A preferred form of the exhausting mechanism is illustrated in Figs. 1 to 5 inclusive. In this example, a jet exhauster of the type above described and a centrifugal liquid pump for furnishing the initial liquid jet are combined in a single unit having a single rotary assembly. A central casing member 33 provided with a supporting base 34 is adapted to house a portion of the separate pump and exhauster chambers, and also the connecting passages therebetween. A casing member 35 cooperates with main casing 33 to inclose the exhauster chamber 37 and the discharge conduit 38 which are much the same as in the form previously described. The casing member 36 cooperates with main casing 33 to inclose a pump chamber 39 which is similar to that of the usual centrifugal pump. A rotary shaft 40 extends through the pump and exhauster chambers and is journaled in bearing 41 intermediate these chambers and in bearings 42 and 43 at the outer sides of each chamber, and the projecting end portions of the shaft are preferably mounted in ball or roller bearings 44 and 45 carried by extending brackets 46 and 47 of the casings 35 and 36 respectively. Shaft 40 is rotated in any suitable manner, for example, by power applied to one projecting end portion 48 thereof. Whew-the rotary shaft passes through the outer walls of the respective pump and exhauster chambers, a packing 49 and gland 50 are provided to prevent the passage of fluids about the rotary shaft. If desired, a stuiing box could be used between the nozzle 58 and bearing sleeve 41.

A centrifugal pump impeller 51 of usual form provided with a plurality of outwardly extending passages 52 is keyed on shaft 46 within the pump chamber 39, and water entering chamber 39 through inlet 53 is forced outwardly by this impeller into the annular passage 54 and thence through port 55 and passage 56 into the entrance tube 57 which is mounted in casing 33 around shaft 40 and projects into the exhauster chamber 37. A restricted annular nozzle 58 at the end of tube 57 projects the water under pressure into the exhauster chamber in the form of an annular jet centered around the axis of shaft 40. 'The nozzle 58 could take the form of a plurality of nozzles arranged in a circular series centered about the axis of shaft 40.

Excess liquid is forced from the pump chamber through a second outlet 55' in the upper portion of discharge conduit 54. The centrifugal pump may also serve as a boiler-feed pump, the water sent to the boiler flowing outthrough outlet 55'.

The exhauster impeller 59 is of much the same type as the impeller 25 previously described, being formed with a circular series of radially extending passages 60, but in this form the inner inlet ends 61 of the several passages curve through the inner face of the impeller and merge to form an annular channel for receiving the jet projected from nozzle 58. This impeller functions as in the first described form of the exhauster to disperse the water particles and project them outwardly between the rings 62 which define the discharge passage 63. The Water particles projected from the impeller together with the entrained fluid from chamber 37 are thrown outwardly into the discharge conduit 38 and flow out through upper outlet 64. The inlet pipe 65 for the gases or other fluids to be exhausted communicates with exhauster chamber 37 through an inlet port in intermediate casing 33.

The operation of this preferred form of the mechanism is much the same as in the simpler form first described, fluid from chamber 37 being first entrained with the circular jet projected from nozzle 58 into the impeller, and

additional fluids being entrained withl the water particles thrown out with' high velocity from the impeller through the annular discharge passage 63. It will be noted that this exhauster unit comprises a single rotating assembly mounted on a single power-driven shaft, the centrifugal pump furnishing the fluid pressure for the initial liquid jet which is projected into the rotary impeller of' the exhauster, which serves to disperse this jet and impart additional velocity thereto so as to` entrain a maximum proportion of fluids from the chamber 37.

As shown in Figs. l, 2 and 5, an automatic throat adjustment is provided by forming a circular conduit or' passage 66 within each ring 62 with an annular outlet channel 67 communicating with the outwardly flared discharge portion of the passage 63 within the rings. A circular series of inlet ports 68 lead to the channel 66 from the discharge conduit 38. When, for any reason, the pressure in the passage 63 decreases, water from conduit 38 will flow through inlets 68, channel 66 and channel 67 into the passage 63 to augment the liquid ow through the channel. In this way fluctuations in pressure or vacuum are compensated for and the device is made self-priming.

As shown in Fig. 3, the impeller 59 may be provided with a central disk or vane 69 (similar to the disk 32 described in. connection with Fig. 6) for increasing the velocity of the fluid discharged through channel 63. AIn the form show in Fig. 4, one side wall of the impeller is extended as shown at 70 to function similarly to the disk 69. It is to be understood that either of these modifications can be used either in conjunction with or separately from-the throat-adjusting form of rings disclosed in Figs. l and5. It is also to be understood that this latter means for adjusting the fluid pressures can be used in the simpler form of apparatus first described and shown in Figs. 6, 7 and 8.

Another modified form of the exhausting appatus is illustrated in Fig. 9. In this form of the apparatus theprotary shaft 7l, which projects into. exhausting chamber 72 in casing 73 and is 'provided with the usual sealing means 74. has a substantially conical deector 75 mounted on its inner end against which the jet of liquid projected from nozzle 76 impacts and is dispersed as an outwardly flaring hollow cone of liquid particles. This deflector 75 may be provided with ribs or blades 75 on its conical surface, the ribs increasing in height from substantially zero height, at the point of the cone, to a maximum height at the base of the cone. p A stationary conical shield 77 ilxed at 78 about the nozzle 76 is adapted to assist in directing the motor liquid dispersed by revolving cone 75 into the restricted annular channel 79 formed between the two conical restricting rings 80 and 8l. The stationary shield 77 and rotary cone 75 exert a mixing action ron the fluids conned therebetween whereby the water is highly dispersed and thrown out as a series of spirals into channel 79. The fluids are discharged into outlet conduit 82 having an upper outlet port 83, as in the forms of the invention first described. The fluids to be exhausted are conducted into chamber 72 through pipe 84, and a plurality of passages 85 through shield 77 leads from chamber -72 into the space within this shield so that fluids from chamber 72 may pass through openings 85 and be entrained with the liquid of the jet both before and after its impact with lconical impeller 75. Additional fluids from chamber 72 are entrainedwith the dispersed particles of liquid that are projected from impeller 75 and shield 77 into the channel 79 between the rings 80 and 81. It will be noted that in this latter form of exhauster the rotating element is very small and simple, and the power consumption will be correspondingly decreased.

It will be noted that in all of the forms of this invention there is no liquid pressure exerted at the bearing where the rotary shaft projects through the casing, and the packing means need only function to prevent the entrance of air at atmospheric pressure, vsince a partial vacuum exists within the exhausting chamber. The rotating parts are small and light, and this small moving mass results in a low power consumption compared with the high exhausting capacity of. the mechanism. The apparatus is self-priming since the water outlet is provided in the top of the casing and water` can flow back to prime the jet mechanism when the impellerrceases to-function.

I claim: Y

l. An exhausting mechanism comprising a closed casing enclosing an exhausting chamber and having an inlet for gases and a restricted annular outlet for mixed fluids, a rotary impeller mounted within exhausting chamber, means for positively rotating the impeller, and means for projecting a stream of liquid through the chamber and against theimpeller, the impeller being formed with means to spread the stream and project it radially through the annnular outlet.

2. An exhausting mechanism comprising a closed casing enclosing an exhausting chamber and having an inlet for gases and a restricted annular outlet for mixed fluids, a rotary impeller mounted within the exhausting chamber and formed with a circular series of substantially radially directed passages veach having a centrally disposed inlet and an outlet directed toward the annular outlet of the casing, means for rotating the impeller, and means for projecting a stream of'liquid through the exhausting chamber and against the impeller, the impeller being formed with means for dispersing the stream laterally among the inlets to the passages.

3. An exhausting mechanism comprising a closed casing enclosing an exhausting chamber having an inlet for gases and a restricted annular outlet for mixed fluids, a rotary impeller mounted within the exhausting chamber and formed with a circular series of substantially radially directed passages, the inlets to the passages being arranged in a circular series at one side of thel impeller centered around the axis of rotation thereof and the outlets of the passages being directed toward the annular -outlet of the casing, and an annular nozzle extending into the casing and centered about the axis of the impeller and adapted to project an annular stream of liquid through the exhausting chamber and into the inlets to the passages.

4; An exhausting mechanism comprising a closed casing enclosing an exhausting chamber having an inlet for gases and a restricted annular outlet for mixed fluids, a rotary impeller mounted within the'exhausting chamber and formed with a circular series of substantially radially directed passages, the inlets to the passages being arranged in a circular series at one side of the impeller centered around the axis of rotation thereof and the outlets of the passages being directed toward the annular outlet of the casing, an annular vane projecting from the periphery of the impeller into 150 the annular outlet passage, and means for projecting/an annular stream of liquid through the chamber and against the impeller and into the inlets to the passages.

5. An exhausting mechanism comprising a casing enclosing a central exhaust chamber, an annular outlet conduit for mixed fluids and a restricted annular passage leading from the chamber to the conduit, there being an inlet for gases leading to the chamber, a rotary impeller positioned within the chamber and formed with a circular series of substantially radially directed passages each having a centrally disposed inlet and an outlet directed toward the annular passage in the casing, means for rotating the impeller, and means for projecting a stream of liquid through the chamber and against the impeller and thence through the passages.

6. An exhausting mechanism comprising a casing enclosing a central exhaust chamber, an annular outlet conduit for mixed fluids and a restricted annular passage leading from the chamber to the conduit, there being an inlet for gases leading to the chamber, a rotary impeller positioned Within the chamber, and formed with a circular series of substantially radially directed passages each having a centrally disposed inlet and an outlet directed toward the annular passage in the casing, means for rotating the impeller, an annular vane projecting from the impeller at the outlets of the passages and into the annular passage, and means for projecting a stream of liquid through the chamber and against the impeller and thence into the passages.

'7. An exhausting mechanism comprising a casing enclosing a central exhaust chamber, an annular outlet conduit for mixed fluids and a restricted annular passage leading from the chamber to the conduit, there being an inlet for gases leading to the chamber, a rotary shaft extending through the casing, means for rotating the shaft, an impeller fixed on the shaft and formed with an annular series of passages extending substantially radially and having inlets arranged in a circular series in one side of the impeller about the shaft and outlets directed toward the annular passage in the casing, and an annular nozzle extending into the casing about the shaft and positioned to project an annular stream of liquid through the chamber and into the inlets to the passages.

8. An exhausting mechanism comprising a casing enclosing a central exhaust chamber, an annular outlet conduit for mixed fluids and a restricted annular passage leading from the chamber to the conduit, there being an inlet for gases leading to the chamber, a rotary shaft extending through the casing, means for rotating the shaft, an impeller fixed on the shaft and formed with an annular series of passages extending substantially radially and having inlets arranged in a circular series in one side of the impeller about the shaft and outlets directed to- .ward the annular passage in the casing, an annular vane extending from the periphery of the impeller at the outlets of the passages and into the annular outlet passage, and an annular nozzle extending into the casing about the shaft and positioned to project an annular stream of liquid through the chamber and into the inlets to the passages.

9. An exhausting mechanism comprising a casing enclosing a central exhaust chamber, an annular outlet conduit for mixed fluids and a restricted annular passage leading from the chamber to the conduit, there being an inlet for gases leading to the chamber, a rotary impeller positioned within the chamber, means for rotating the impeller, and means for projecting a stream of liquid into and through the chamber and against the impeller and thence through the annular passage, the annular passage between the exhaust chamber and outlet conduit being formed between a pair of restricting rings mounted in the casing and having convex faces opposed to one another.

10. An lexhausting mechanism comprising a casing enclosing a central exhaust chamber, an annular outlet conduit for mixed fluids and a restricted annular passage leading from the chamber to the conduit, there being an inlet for gases leading to the chamber, a rotary impeller positioned within the chamber, means for rotating the impeller; and means for projecting a stream of liquid into and through the chamber and against the impeller and thence through the annular passage, the annular passage between the exhaust chamber and outlet conduit being formed between a pair of restricting rings mounted in the casing and having convex faces opposed to one another, each ring being formed with an internal annular passage which connects through the convex interior face of the ring with the passage between the rings and through the outer face of the ring with the outlet conduit.

11. An exhausting mechanism comprising a casing enclosing an exhauster chamber, an inlet to the chamber for fluids to be exhausted, a substantially conical impeller mounted for rotation Within the chamber, means for rotating the impeller, a nozzle extending into the chamber and adapted to project a stream of liquid under pressurel through the chamber and against the impeller substantially in line with the' axis of rotation thereof, a conical directing shield flxedly positioned about the nozzle and impeller, there i being suction passages extending through the shield from the chamber to the space between the nozzle and impeller, there being an annular outlet conduit formed in the casing and a restricted annular passage leading from the chamber to the conduit, the conical shield directing fluids from the impeller outwardly through the annular passage together with additional fluids entrained from the exhauster chamber.

12. An exhausting mechanism comprising a casing enclosing a pump chamber and an exhauster chamber, an inlet -for liquid leading to the pump chamber, an inlet for fluids to be exhausted leading to the exhauster chamber, a rotary shaft extending through both chambers, a centrifugal pump impeller mounted on the shaft within the pump chamber, an annular outlet nozzle for liquid under pressure extending around the shaft from the outlet of the pump chamber and into the exhauster chamber, an exhauster impeller fixed on the shaft within the exhauster chamber, said exhauster chamber having a restricted annular outlet passage for mixed fluids, said exhauster impeller being adapted to direct liquid projected through the chamber and thereagainst from the nozzle through the outlet passage together with entrained fluids from the exhauster chamber.

13. An exhausting mechanism comprising a casing enclosing a pump chamber and an exhauster chamber, an inlet for liquid leading to the pump chamber, an inlet forfluids to be exhausted leading to the exhauster chamber, a rotary shaft extending through both chambers, a

centrifugal pump impeller mounted on the shaft within the pump chamber, an annular outlet nozzle for liquid under pressure extending around the shaft from the outlet of the pump chamber and into the exhauster chamber, an exhauster impeller fixed on the shaft within the exhauster chamber, said exhauster chamber having a restricted annular outlet passage for mixed fluids, said exhauster impeller being formed with a circular series of substantially radial passages having inlets arranged about the shaft to receive liquid projected from the nozzle through lthe chamber and against the impeller and outlets positioned to direct the liquid through the annular outlet passage together with entrained uids from the chamber.

14. An exhausting mechanism comprising a casing enclosing an exhauster chamber, an inlet to the chamber for iiuids to be exhausted, a substantially conical impeller mounted for rotation within the chamber, means for rotating the impeller, a nozzle extending into the chamber and adapted to project a stream of liquid under pressure through the chamber and against the impeller substantially inline with the axis of rotation thereof, a conical directing shield iixedly positioned about the nozzle and impeller, there being an annular outlet conduit formed in the casing and a restricted annular passage leading from the chamber to the conduit, the conical shield directing fluids from the impeller outwardly through the annular passage together with additional uids entrained from the exhauster chamber. v

15. An exhausting mechanism comprising a casing enclosing an exhauster chamber, an inlet zle and impeller, there being an annular outlet conduit formed in the casing and a restricted annular passage leading from the chamber to the conduit, the conical shield directing fluids from the impeller outwardly through the annular pas- I sage together with additional iiuids entrained I from the exhauster chamber.

DAVID N. CROSTHWAIT, Jn.

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