Axial thrust balancing device for pumps

• US 4,538,960 A
• Filed: 02/13/1981
• Issued: 09/03/1985
• Est. Priority Date: 02/18/1980
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Iino, Toshiki, Kamata, Kunio
• Primary Examiner(s): Yuen, Henry C.
• Assistant Examiner(s): Kwon, John
• Application Number:
  US06/234,178
• Time in Patent Office: 1,663 Days
• Field of Search: 415/104, 415/105, 415/106, 415/112
• US Class Current: 415/104
• CPC Class Codes: F01D 3/04 axial thrust being compensated by thrust-balancing dummy piston or the like
• CPC Class Codes: F04D 29/0416 balancing pistons

Abstract

This invention relates to an axial thrust balancing device for pumps which cancels an axial thrust caused by impellers by utilizing a discharge water pressure. In the device, there is provided a small axial gap between a low pressure sidewall of a balancing drum tightly fitted over a shaft of impellers and a flange-like end wall extending inwardly from a stationary wall along the low pressure sidewall of said balancing drum. On application of the device to a vertical pump, in particular, the balancing drum is prevented from being in contact with the end wall during suspension of operation.

Claims

1. An axial thrust balancing device for pumps, the thrust balancing device comprising:

a balancing drum secured to a shaft of impellers at a side of a last stage of said impellers for rotation therewith;

a stationary wall having a flange-like end wall portion extending inwardly along a low pressure sidewall of said balancing drum;

a small annular gap defined between said balancing drum and said stationary wall;

a small annular axial gap defined between the low pressure sidewall of said balancing drum and the end wall portion of the stationary wall at a small radius position;

a high pressure chamber defined by the last stage of said impellers, said stationary wall and the high pressure side wall of said balancing drum;

an intermediate pressure chamber defined between said annular gap and said axial gap by said flange-like end wall portion of said stationary wall and the low pressure sidewall of said balancing drum; and

a low pressure chamber defined at a rear side of said flange-like end wall portion of said stationary wall.

2. An axial thrust balancing device according to claim 1, wherein said pump is a vertical pump including a rotary shaft with a bearing means adapted for rotatably supporting the shaft in a vertical direction, a casing means for supporting said bearing, and a projection means extending from said casing for limiting a downward movement of said bearing means.