US3898015A

US3898015A - Submergible liquid pump

Info

Publication number: US3898015A
Application number: US439765A
Authority: US
Inventors: Olav Rasmusson Navelsaker
Original assignee: Thune Eureka AS
Current assignee: Thune Eureka AS
Priority date: 1973-07-05
Filing date: 1974-02-05
Publication date: 1975-08-05
Anticipated expiration: 1992-08-05
Also published as: DE2405772B2; DE2405772C3; ES423425A1; DE2405772A1; NO138608C; NO138608B; JPS5023002A; SE7402151L; NO276673L

Abstract

A submergible liquid pump is provided with a leakage-collecting chamber arranged around the drive shaft. The leakage-collecting chamber is defined by a stationary wall and by a wall rotating with the drive shaft. Leakage hurled outwards during operation of the pump is collected with a means arranged in the leakagecollecting chamber and thus removed from the leakage-collecting chamber.

Description

United States Patent 1191 Navelsaker Au 5, 1975 [54] SUBMERGIBLE LIQUID PUMP FOREIGN PATENTS OR APPLICATIONS lnvemori Olav Rasmflsson Navelsaker, 24,985 1907 United Kingdom 415/89 Nordengveren, Norway 915,046 8/1954 Germany 277/25 [73] Assignee: Thune-Eureka A/S, Oslo, Norway [22] Filed: Feb 5 1974 Primary E.\'amfner-Henry F. Raduazo Attorney, Agent} or FirmYoung & Thompson [21] Appl. No: 439,765

[30] Foreign Application Priority Data [57] ABSTRACT July 5, 1973 Norway 2766/73 A submerglble lrquld pump 1s provlded w1th a leakage- [52] us CL 415/111; 415/168. 277/25. collecting chamber arranged around the drive shaft.

415/89 The leakage-collecting chamber is defined by a sta- 51 Int. Cl. F0ld 25/32 tionary and by a rotating with the drive Shaft [58] Field of Search 277/25; 415/111, 169 A, Leakage hurled outwards during 0106mm 415/89 168 pump is collected with a means arranged in the leakage-collecting chamber and thus removed from the [56] References Cited leakage-collecting chamber.

UNITED STATES PATENTS 1/l974 Lewis 4l5/89 4 Claims, 1 Drawing Figure SUBMERGIBLE LIQUID PUMP The invention relates to a submergible liquid pump having a leakage-collecting chamber arranged around the drive shaft.

In such pump units, which are generally utilized onboard ships, the sealing for the hydraulic oil is, as a rule, a mechanical sealing of extremely good quality. The sealing operates under ideal conditions with controlled oil circulation which means substantially zero leakage and a lifetime of several years of continuous operation. Any oil leakage is conveyed by a throw-off ring on the drive shaft to a separate leakage-collecting chamber which can receive substantially more oil than the amount possibly leaking from bearing housing and stationary hydraulic motor. By means of a neutral pressure gas, the leakage in the leakage-collecting chamber can be transported from the leakage-collecting cham' ber and, for example, up to the deck of the ship.

The object of the present invention is to improve the sealing arrangement in pumps of the type described introductorily, and also to achieve an automatic trans port of leakage to the deck.

In accordance with the invention, this is achieved in that the leakage-collecting chamber is formed as a rotary leakage-collecting chamber in that it is defined by a stationary wall and by a wall rotating with the drive shaft. During operation of the pump, any leakage is then hurled outwardly in the leakage-collecting chamber and can be collected by a means arranged in the leakage-collecting chamber connected to a conduit which, for example, can lead up to a vessel on deck. When the pump is operating, any leakage is hurled out by centrifugal force, and forms a ring outermost in the leakage-collecting chamber, at a pressure sufficient to press the leakage up to, for example a vessel.

The wall rotating with the drive shaft in the leakagecollecting chamber can be formed as a separate element mounted to the drive shaft; however, when concerned with a centrifugal pump, it can to advantage be formed by the impeller of the pump.

The means for collecting leakage hurled out during operation can be a pick-up valve. The said pick-up valve may be combined with a check valve for expelling leakage during standstill by means of a neutral pressure gas supplied to the leakage-collecting chamber.

According to the invention, therefore, a valve unit is provided which comprises two check valves having a common spring but having greater seat diameter for the check valve used during standstill whenthe leakage is expelled by means of a neutral pressure gas. When the leakage-collecting chamber is subjected to gas pressure, the combined valve permits any oil leakage to be transported from the bottom of the leakage-collecting chamber through the largest check valve and up through an oil leakage tube. The opening pressure for the smaller valve is greater, due to the common spring and due to the difference in seat diameter, such that the gas pressure cannot escape this way, that is to say through the actual pick-up valve. During operation, the dynamic pressure of the leakage ring drives the leakage through the smaller valve, the larger valve'remaining sealed, and also in this case the leakage will be trans ported to the deck, on the action of the dynamic pressure.

The leakage-collecting chamber is utilized preferably together with a so-called pressure chamber formed in the bearing housing above the leakage-collecting chamber, in that the wall rotating with the drive shaft, or the impeller, respectively, are provided with an extension in the form of a collar projecting upwards and into the chamber around a wall therein, to form a rotation slot between the leakage-collecting chamber and the pressure chamber.

Preferably, a check valve is arranged in the communication between the pressure chamber and the leakage-collecting chamber, the said check valve being open during operation of the pump.

The invention is further explained hereinbelow by means of an embodiment example illustrated on the FIGURE.

The FIGURE illustrates a section through a submergible pump. The essential components illustrated are the bearing housing 24, the drive shaft 20, the impeller 27 mounted on the drive shaft in the pump, and the inlet housing 33.

The drive shaft 20 is mounted in the bearing housing 24 by means of

ball bearings

22 and 23. The drive shaft 20 means from the hydraulic motor 21 indicated.

The impeller 27 together with the bearing housing 24 define a leakage-collecting chamber 26.

The leakage-collecting chamber can, of course, also be limited by a separate part which is mounted on the drive shaft and rotates therewith and does not constitute any part of the impeller, which may be the case when the suction opening of the impeller faces upwardly, or where a so-called two-way impeller is concerned. The modifications then necessary in the construction are so obvious to a skilled person and are not further illustrated or described therefore.

A pressure chamber 28 is formed in the bearing housing above the leakage-collecting chamber 26. The upper collar 29 of the impeller 27 extends into the pressure chamber 28 and widens gently upwardly and outwardly. The collar 29 is provided with transport threads 30 which face in towards the rotation slot 31 formed between the collar 29 and the bearing housing 24. The pressure chamber 28 is defined at the bottom thereof by the upper wear-ring 32 of the pump.

The inlet housing 34 is provided with a casing 33 facing downwardly toward the cargo, said casing forming a pre-compression chamber 34. The said precompression chamber is in communication with the pressure chamber 28 by means of openings 35.

Neutral pressure gas is supplied to the leakagecollecting chamber 26 through a conduit, not shown. The pressure chamber which is disposed cylindrically around the upper collar 2 of the impeller, is subjected to pressure when the pump is submerged in the cargo, leakage occuring through the wear-ring slot and through the openings 35 from a pre-compression chamber 34 formed by a casing 33. The said openings have a double function: primarily as side channels for the wear-ring leakage and secondarily as pressure openings between the pre-compression chamber and the pressure chamber. When the pump is submerged in the cargo, the cargo rises rapidly to the wear-ring 32 internally. In the precompression chamber 34, the air is then subjected to a certain liquid pressure. This pressure is transmitted to the pressure chamber since the liquid flows more slowly through the wear-ring slot than the air flows in from the compression chamber. When the liquid or cargo level is in balance, it will be at a lower level in the pressure chamber than if the precompression chamber effect had not been present. In this manner, the greatest possible gascontacted surface on the impeller is achieved, such that the disc-loss is reduced to a minimum even of the neutral gas is not utilized. Obviously, this effect can also be achieved when a separate, completely rotating wall is utilized for defining the leakage-collecting chamber.

The inner, outwardly widening impeller collar 29 which is provided with transport threads represents an extra safety arrangement which comes into force if the pump should inadvertently be disposed in horizontal position for a period of time. The transport threads counteract the penetration of cargo and when the pressure is in balance over the slot, gas will not flow out if liquid cannot penetrate. Oil leakage will automatically be transported to the deck, also in this position.

In the slot between the impeller collar 29 and the bearing housing 24 a check valve 36 is arranged which includes an annular sealing lip made from a resilient material and has self-lubricating properties and is of sufficient hardness and density for the purpose. The sealing lip may be circular or may be divided into segments which do not necessarily need to seal against one another. During standstill, that is to say, when the shaft is stationary, the sealing lip 10 is maintained pressed against the inner cylinder surface in the slot, i.e. against the bearing housing 24, by means of a surrounding endless helical spring 11. The helical spring is arranged in a groove 12 in the collar 29. The spring may be provided with ballast, either in the form of an internal endless tube filled with lead (shot or granulate) and of suitable reciliency, or in another manner. Axially opposing the lip 10, the sealing element is formed to seal against the outer rotary portion, i.e. against the impeller collar 29, in this case by means of the O-ring 8 indicated. The whole sealing arrangement is adapted such that the sealing lip and spring are capable of moving radially on the action of the centrifugal force when the impeller rotates, whereby the valve is in open position.

From the bottom of the leakage-collecting chamber 26, an oil leakage tube 9 leads up to a check valve 41. From there, a bore leads up further through the bearing housing. The said bore 25 is connected, in manner not illustrated, to a conduit which leads up to a vessel on deck.

During standstill, neutral gas may be supplied through a conduit (not shown) to the leakagecollecting chamber 26 and any oil leakage present in the leakage-collecting chamber is then forced out through the bore 9, the check valve 41 and up through the bore 25 to a vessel on deck.

When the pump is in operation, any leakage will be hurled outwardly by centrifugal force in the leakagecollecting chamber and forms a ring outermost in the leakage-collecting chamber, at a pressure which is sufficiently great to press the leakage to a vessel on deck, through a check valve 37. The said check valve 37 is, through a bore 42, in communication with a bore 40 which faces towards the liquid flow. When the pressure of the oil leakage ring is sufficiently high, the check valve 27 opens and the leakage may then flow up through the bore 25 to a vessel on deck.

The two check valves 41 and 37 are, as illustrated, assembled as a unit and have a common spring 43. The inner check valve 41 has a larger seat diameter than the outer check valve 37. When the leakage-collecting chamber is subjected to gas pressure, during standstill, the arrangement permits any leakage to be conveyed from the bottom of the leakage-collecting chamber through the inner check valve 41 and up to the deck; the opening pressure of the outer valve 37 being greater due to the common spring 43 and due to the difference in seat diameter, so that the gas pressure cannot escape this way. During operation, the dynamic pressure of the leakage ring drives the leakage through the outer check valve 37, the inner check valve 41 then remaining sealed, and the leakage is therefore conveyed to the deck.

The invention is hereinbefore described in connection with a specific embodiment but is, of course, not restricted thereto. As already mentioned, the rotating wall of the leakage-collecting chamber can be an element which is independent of the impeller, and the construction is then modified as necessary.

Having described my invention, I claim:

1. A submergible liquid pump having a leakagecollecting chamber arranged around a drive shaft of the pump, said leakage-collecting chamber being defined by a stationary wall and by a wall rotating with the said drive shaft, means in the said leakage-collecting chamber for removing collected leakage hurled outwards in theleakage-chamber during operation of the pump by said rotating wall, a bearing housing for the said drive shaft, the said bearing housing defining the said stationary wall, a pressure chamber in the said bearing housing extending around the said drive shaft above the said leakage-collecting chamber, which pressure chamber is downwardly exposed, an extension in the form of a collar projecting upwardly from the said wall rotating with the drive shaft and into the said pressure chamber, the said collar being adjacent a wall of the said pressure chamber thereby forming a rotation slot between the said leakage-collecting chamber and the said pressure chamber, and a pre-compression chamber in the form of a downwardly open easing into which said pressure chamber opens.

2. A submergible pump as claimed in claim 1, and a check valve in said rotation slot, said check valve being opened during operation of said pump.

3. A submergible pump as claimed in claim 1, said liquid pump comprising a centrifugal pump with an impeller, said wall rotating with the drive shaft comprising a part of said impeller.

4. A submergible liquid pump having a leakagecollecting chamber arranged around a vertical drive shaft of the pump, said leakage-collecting chamber being defined by a stationary wall and by an upwardly extending wall rotating with the said drive shaft, means in the said leakage-collecting chamber for removing collected leakage hurled outwards in the leakagechamber during operation of the pump by said rotating wall, said stationary wall and said rotating wall defining a passage which leads from the lowest part of the said leakage-collecting chamber, a first check valve in said means and, a second check valve in the said means, and a common spring for the two said check valves, said first check valve having a greater valve seat diameter than said second check valve.

Claims

1. A submergible liquid pump having a leakage-collecting chamber arranged around a drive shaft of the pump, said leakagecollecting chamber being defined by a stationary wall and by a wall rotating with the said drive shaft, means in the said leakage-collecting chamber for removing collected leakage hurled outwards in the leakage-chamber during operation of the pump by said rotating wall, a bearing housing for the said drive shaft, the said bearing housing defining the said stationary wall, a pressure chamber in the said bearing housing extending around the said drive shaft above the said leakage-collecting chamber, which pressure chamber is downwardly exposed, an extension in the form of a collar projecting upwardly from the said wall rotating with the drive shaft and into the said pressure chamber, the said collar being adjacent a wall of the said pressure chamber thereby forming a rotation slot between the said leakage-collecting chamber and the said pressure chamber, and a pre-compression chamber in the form of a downwardly open casing into which said pressure chamber opens.

4. A submergible liquid pump having a leakage-collecting chamber arranged around a vertical drive shaft of the pump, said leakage-collecting chamber being defined by a stationary wall and by an upwardly extending wall rotating with the said drive shaft, means in the said leakage-collecting chamber for removing collected leakage hurled outwards in the leakage-chamber during operation of the pump by said rotating wall, said stationary wall and said rotating wall defining a passage which leads from the lowest part of the said leakage-collecting chamber, a first check valve in said means and, a second check valve in the said means, and a common spring for the two said check valves, said first check valve having a greater valve seat diameter than said second check valve.