AU648560B2 - Surge damper - Google Patents

Description

38986 HKS:LL P/00/01i1 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT 0~ 0 0 0* 0 0

S

*0S0 00 0 00 t .0* 0 000e@ 0o

SO

0* 0 00 00 0 *e .0 0* 0 000 0* 0 0 00 30 Name of Applicant: TECALEMIT (AUSTRALASIA) PTY LTD Actual Inventor: ROGER MoE WAN CARROLL Address for Service: COLLISON CO.,117 King William Street, Adelaide, S.A. 5000 Invention Title: SURGE DAMPER Details of Associated Provisional Applications: No: PK0829 dated 27th June 1990 The following statement is a full description of this invention, including the best method of performing It known to us: This invention relates to a surge damper, or pulsation damper to produce a more even flow or relatively smooth flow rate of fluid from a reciprocating pump.

In the art of pumping fluids with a reciprocating pump, due to the reciprocating action of the pump, pressure pulses and surges occur from the pumping action.

The sudden opening and closing of valves can also produce vibration or water hammer in the fluid flow lines. In order to overcome these problems air chambers, pulsation dampers, and surge dampers are provided in the fluid flow lines from the reciprocation pumps. However, these are separate items and must be included in and positioned in the output line from the pump.

The design and positioning of pulsation dampers in fluid flow lines is well known and are generally accepted as being efficient in reducing pressure pulses and surges. The problem with the current art is that it is inconvenient to provide additional apparatus to control pressure pulses. It would be far more convenient if the problem could be alleviated by modification of the pump.

It is an object of this invention to provide a damper which is not a separate item but is included in the reciprocating pump itself.

Thus there is provided according to one form of the invention a reciprocating pump incorporating a surge damper, the pump comprising a barrel, a foot valve at one end of the barrel and an outlet at the other end of the barrel, a pump piston rod and pump picton moUnted thereto adapted to move in reciprocating motion within the barrel, the pump piston defining within the barrel a suction side and a pressure side of the pump, and valve means to allow transfer of pumped fluid from the suction side to the pressure side but to prevent transfer in the opposite direction, characterised by the surge damper being incorporated *within the pump piston rod, the pump piston rod being hollow to define a damper cylinder therein, the cylinder being closed at one end and opening at the other end to the pressure side of the pump, a physical barrier being freely moveable within the cylinder to define a pumped fluid side and an energy 35 absorbing side of the physical barrier, and an energy absorbing means on the energy absorbing side of the physical barrier whereby forces exerted by the instantaneous pressure of pumped fluid are substantially damped by the surge damper.

ooo7 The physical barrier may be a piston, a diaphragm or bladder within the cylinder.

Preferably the energy absorbing means is air, compressible fluid or gas or alternatively it may be a spring or it may be a combination of air or gas ar spring.

In order to more fully describe the invention reference will now be made to the accompanying drawing which shows one form of the invention.

Referring to the drawing, there is shown a reciprocating pump 1 having a pump barrel 2, foot valve 3 with inlet 4 at one end of the barrel 2, and a cap 5 at the other end of the barrel. The cap having an outlet 6 and sealing gland 7 for the pump piston rod 8. The lower end of the piston rod 8 is hollow to form a damper tube 11 which is sealed at the top end and provided at its lower end with a member 12 and a stem 13 connecting to the piston 9 and valve There is a spring 17 provided on the stem 13 and appropriate sealing rings 18 on the piston 9. The piston 9 is also provided with passageways 19 through which fluid moves in the normal operation of the pump.

The piston 9 and the valve 10 act together to form a one way valve. During the upstroke, fluid cannot pass the valve but on the downstroke the piston 9 moves off the valve seat on the valve 10 against the pressure of spring 17 to allow fluid flow from the suction side of the pump to the pressure side.

*0.

The member 12 has connecting passages 14 to connect the interior of the damper tube 11 to the working chamber of the pump.

S: The surge damper in this embodiment is provided within the damper tube 11 which contains a freely moveable piston damper 15 with sealing rings 16. Air or gas is trapped in the region 20 between the closed end of the tube 11 and the piston damper o e• a •*oo o* 0* Thus during the up or down discharge stroke of the pump the pressure in the working chamber of the pump will cause the damper piston to move compressing the air or gas trapped on the opposite side of the damper piston.

Thus this movement of the damper piston into the cylinder will compress the air or gas until the force exerted by the pressure of the compressed air or gas balances the force exerted by the instantaneous pressure of the pumped fluid.

The compre.sesad gas acts as a non-linear spring, storing the energy as the pumping system builds up pressure and releasing energy as the pressure d-"-ays. This action will smooth the pump output as the pump piston reverses d, .ction at each end of its stroke and sudden changes in pressure will be damped by the compliance of the damper piston against the compressed gas.

In an alternative form of the invention, instead of the piston damper 15 with sealing rings 16 in the tube damper 11, a flexible diaphragm or a flexible bladder can be incorporated into the tube damper 11. The diaphragm may roll on itself as the pressure varies, and if a flexible bladder is used containing air or gas, then the variation in pressure will compress the air or gas in the bladder.

In other forms of the invention, the compressed gas may be replaced by a spring inside the tube damper 11 acting on the piston damper 15, or in combination with the said air or gas inside the region While the invention can be applied to various types of reciprocating pumps, it is shown as applied to a double acting pump where the hollow piston rod is the pump equalizer or surge damper and also the connecting tube to an air motor.

The piston or reciprocating pump shown in this embodiment is a double acting pump, that is it pumps fluid both on the upstroke and the downstroke of the pump. The surge damper of the present invention may also be used with a single acting pump. Various methods can be applied to drive the pump such as the air motor of the present embodiment or a crank drive system.

0*e o• 3 Although various forms of the invention have been described in some detail, the invention is not to be limited thereto but can include various forms and .modifications falling within the spirit and scope of the invention.

Claims (5)

1. A reciprocating pump incorporating a surge damper, the pump comprising a barrel, a foot valve at one end of the barrel and an outlet at the other end of the barrel, a pump piston rod and pump piston mounted thereto adapted to move in reciprocating motion within the barrel, the pump piston defining within the barrel a suction side and a pressure side of the pump, and valve means to allow transfer of pumped fluid from the suction side to the pressure side but to prevent transfer in the opposite direction, characterised by the surge damper being incorporated within the pump piston rod, the pump piston rod being hollow to define a damper cylinder therein, the cylinder being closed at one end and opening at the other end to the pressure side of the pump, a physical barrier being freely moveable within the cylinder to define a pumped fluid side and an energy absorbing side of the physical barrier, and an energy absorbing means on the energy absorbing side of the physical barrier whereby forces exerted by the instantaneous pressure of pumped fluid are substantially damped by the surge damper.

2. A reciprocating pump as in claim 1, wherein the physical barrier is a damper piston freely moveable within the cylinder.

3. A reciprocating pump as in claim 1, wherein the physical barrier is a diaphragm. 00.40: l 4. A reciprocating pump as in claim 1, wherein the physical barrier is a flexible sealed bladder within the cylinder having a compressible fluid within the bladder. S

5. A reciprocating pump as in any one of claims 1 to 3 wherein the energy absorbing means is selected from air, gas, a compressible fluid, a spring or a combination of a spring and air or gas. S° 35 6. A reciprocating pump substantially as hereinbefore described with reference to the drawings. DAT~ED this 25th day of Feburary 1994 .E TEALEMIT (AUSTRAUASIA) pTY LTD By their Patent Attorneys ;;6FP Lqj OOLISON C). ABSTRACT A surge damper incorporated in a reciprocating pump and integrally formed with a piston rod of the pump. The damper comprises a cylinder closed at one end and open at another end to a pressure side of the pump. A piston within the cylinder is free to move when subjected to an unbalance of pressure from either side of the piston, there being an ene.rgy absorbing means within the cylinder between the piston and the closed end. The energy absorbing means acts as a non-linear spring to dampen the pressure surges associated with the pumping action. *.0 ea eS

9. 9