Pump incorporating pressure-regulated venting means

• US 5,772,412 A
• Filed: 08/14/1996
• Issued: 06/30/1998
• Est. Priority Date: 12/22/1993
• Status: Expired due to Term

• Current Assignee: Pentair International SÀRL (Pentair Plc (Ireland))
• Original Assignee: Shurflo Ltd. (Pentair Plc (Ireland))
• Inventors: Zytynski, Zbigniew Janusz
• Primary Examiner(s): Thorpe, Timothy
• Assistant Examiner(s): Kim, Ted
• Application Number:
  US08/666,551
• Time in Patent Office: 685 Days
• Field of Search: 417/393, 417/395, 92/220
• US Class Current: 417/393
• CPC Class Codes: F04B 43/0081 systems, control, safety measures
• CPC Class Codes: F04B 43/0736 with two or more pumping chambers in parallel

Abstract

The invention provides a pump comprising at least one piston (26, 28) movable in a reciprocating manner within a chamber (12), sealing means (32a, 32b) located between the piston (26, 28) and the interior wall of the chamber (12), and venting means (36) for venting a portion of the chamber (12) bounded by the interior wall, the piston (26, 28) and the sealing means (32a, 32b), wherein the venting means (36) incorporates pressure regulating means (40) such that the pressure to which the said portion of the chamber (12) is vented can be regulated. This reduces the pressure differences across the or each sealing means and thus reduces deterioration and damage.

Claims

1. A pump comprising:

a chamber having an inlet and an outlet, the inlet and the outlet being opened and closed by valve means for the passage of a pumped fluid;

at least one piston movable in a reciprocating manner within said chamber;

sealing means located between the piston and the interior wall of the chamber;

introduction means for introducing a working fluid into a portion of the chamber bounded by the interior wall of the chamber, the piston and the sealing means; and

venting means for venting the portion of the chamber so that alternate introduction of the working fluid into, and venting of the working fluid from, the portion of the chamber causes the piston to move in a reciprocating manner to transport the pumped fluid through the chamber from the inlet to the outlet,

wherein the venting means incorporates pressure regulating means to regulate, in dependence upon the pressure of the pumped fluid, the pressure to which the said portion of the chamber is vented such that, in use, the pressure of the working fluid in the said portion of the chamber is prevented from falling, during venting, below the pressure of the pumped fluid in the chamber.

2. A pump as claimed in claim 1, wherein the pressure regulating means comprise sensors for sensing the pressure of the fluid being pumped by the pump and means for controlling the regulated pressure in accordance with the pressure sensed by the sensors.

3. A pump as claimed in claim 1, wherein the regulating means comprise a movable shut-off valve responsive in use to the difference between the pressure within the said portion of the chamber and the pressure of the pumped fluid in the chamber.

4. A pump as claimed in claim 3, wherein the movable shut-off valve is movable between an open position allowing venting of the said portion of the chamber and a closed position preventing venting of the said portion of the chamber, the valve being moved from the open position to the closed position when, in use, the pressure in the said portion of the chamber drops below the pressure of the pumped fluid in the chamber.

5. A pump as claimed in claim 4, wherein the movable shut-off valve comprises a diaphragm exposed, in use, on one side to the fluid being pumped by the pump and on the other side to the vented contents of the said portion of the chamber.

6. A pump as claimed in claim 1, wherein two pistons are located in the chamber.

7. A pump as claimed in claim 1, wherein the sealing means comprise at least one rolling diaphragm seal.

8. A pumping system for pumping a fluid from at least one reservoir to at least one dispensing point, said system comprising at least one pump and attachment means for connecting said at least one pump to said at least one reservoir, said at least one pump comprising:

a chamber having an inlet and an outlet, the inlet and outlet being opened and closed by valve means for the passage of the pumped fluid;

at least one piston movable in a reciprocating manner within said chamber;

sealing means located between the piston and the interior wall of the chamber;

introduction means for introducing a working fluid into a portion of the chamber bounded by the interior wall of the chamber, the piston and the sealing means; and

venting means for venting the portion of the chamber so that alternate introduction of the working fluid into, and venting of the working fluid from, the portion of the chamber causes the piston to move in a reciprocating manner to transport the pumped fluid through the chamber from the inlet to the outlet,

wherein the venting means incorporates pressure regulating means to regulate, in dependence upon the pressure of the pumped fluid, the pressure to which the said portion of the chamber is vented such that, in use, the pressure of the working fluid in the said portion of the chamber is prevented from falling, during venting, below the pressure of the pumped fluid in the chamber.

9. A pumping system as claimed in claim 8, wherein a plurality of dispensing points are provided and a separate pump is associated with each dispensing point.

10. A method of pumping a fluid using a pump, the pump comprising:

a chamber having an inlet and an outlet, the inlet and outlet being opened and closed by valve means for the passage of the pumped fluid;

at least one piston movable in a reciprocating manner within said chamber;

sealing means located between the piston and the interior wall of the chamber;

introduction means for introducing a working fluid into a portion of the chamber bounded by the interior wall of the chamber, the piston and the sealing means; and

venting means for venting the portion of the chamber so that alternate introduction of the working fluid into, and venting of the working fluid from, the portion of the chamber causes the piston to move in a reciprocating manner to transport the pumped fluid through the chamber from the inlet to the outlet,

wherein the venting means incorporates pressure regulating means to regulate, in dependence upon the pressure of the pumped fluid, the pressure to which the said portion of the chamber is vented such that, in use, the pressure of the working fluid in the said portion of the chamber is prevented from falling, during venting, below the pressure of the pumped fluid in the chamber,

the method comprising the steps of causing said at least one piston to move within the chamber, and venting said portion of the chamber, wherein the venting is regulated, in dependence upon the pressure of the pumped fluid, so as to maintain the pressure in the said portion of the chamber substantially at the pressure acting on the sealing means on the side thereof remote from the said portion of the chamber.

11. A method as claimed in claim 10, wherein carbon dioxide gas is used to cause reciprocating movement of said piston within said portion of the chamber.