Method and apparatus for reducing free flow risk

• US 20060182637A1
• Filed: 02/16/2005
• Published: 08/17/2006
• Est. Priority Date: 02/16/2005
• Status: Active Grant

• Current Assignee: Jacobsen Innovations Inc.
• Original Assignee: Sarcos Investments LC
• Inventors: Jacobsen, Stephen C., Brydon, Christopher, Beck, Jon
• Granted Patent: US 7,628,590 B2
• Time in Patent Office: Days
• US Class Current: 417/53
• CPC Class Codes: A61M 2205/3351 Controlling upstream pump pressure
• CPC Class Codes: A61M 2205/3355 Controlling downstream pump pressure
• CPC Class Codes: A61M 5/14212 Pumping with an aspiration and an expulsion action
• CPC Class Codes: A61M 5/16813 by controlling the degree of opening of the flow line
• CPC Class Codes: F04B 49/10 Other safety measures
• CPC Class Codes: Y10T 137/2605 Pressure responsive

Abstract

A technique for reducing the risk of free flow through a pump is disclosed. The technique includes sensing a pressure difference between the pump inlet and outlet. The pressure difference is mechanically communicated to a flow restricting element. The flow restricting element increases resistance to flow exiting the pump outlet in a relation to the pressure difference present between the pump inlet and pump outlet.

Claims

1. A method for reducing a risk of external pressure induced free flow through a pump having an inlet and an outlet comprising:

sensing a pressure difference between an inlet pressure and an outlet pressure;

mechanically communicating the pressure difference to a flow restricting element associated with the pump outlet; and

increasing a resistance to flow exiting the pump outlet with the flow restricting element when the inlet pressure exceeds the outlet pressure.

2. The method of claim 1 wherein mechanically communicating the pressure difference comprises mechanically moving an element of the flow restricting element in proportion to the pressure difference.

3. The method of claim 1 wherein mechanically communicating the pressure difference comprises applying a force to an element of the flow restricting element in proportion to the pressure difference.

4. The method of claim 1 wherein increasing a resistance to flow exiting the pump outlet further comprises limiting the flow exiting the pump outlet in proportion to the pressure difference.

5. The method of claim 1 wherein increasing a resistance to flow exiting the pump outlet further comprises moving the flow restricting element within a fluid channel coupled to the pump outlet to reduce a cross-sectional area of the fluid channel.

6. The method of claim 1 wherein increasing a resistance to flow exiting the pump outlet further comprises increasing a cracking pressure of the flow restricting element.

7. The method of claim 1 wherein increasing a resistance to flow exiting the pump outlet further comprises completely blocking flow through the flow restricting element when the inlet pressure exceeds the outlet pressure.

8. An apparatus for reducing free flow risk comprising:

a pump having a pump inlet and pump outlet, configured to transfer fluid received from the pump inlet to the pump outlet;

a pressure responsive member coupled to the pump inlet and coupled to the pump outlet and configured to mechanically respond to a pressure difference between the pump inlet and the pump outlet; and

a flow restrictor fluidly coupled to the pump outlet and mechanically coupled to the pressure responsive member so as to limit fluid flow exiting the pump outlet in relation to the pressure difference.

9. The apparatus of claim 8 wherein the flow restrictor is further configured to limit fluid flow exiting the pump outlet in proportion to the pressure difference.

10. The apparatus of claim 8 wherein the flow restrictor is further configured to substantially prevent fluid flow exiting the pump outlet when the pressure difference is positive.

11. The apparatus of claim 8 wherein the flow restrictor comprises a pinch valve.

12. The apparatus of claim 8 wherein the flow restrictor comprises a ball valve.

13. The apparatus of claim 12 wherein the ball valve is coupled to the pressure responsive member so that the ball valve has a variable cracking pressure.

14. The apparatus of claim 13 wherein the ball valve comprises a spring configured to set an initial cracking pressure.

15. The apparatus of claim 8 wherein the pressure responsive member comprises a moveable element disposed within a chamber and coupled to the flow restricting element, wherein a first side of the moveable element defines a first part of the chamber, the first part of the chamber in pressure transmitting relation with the pump inlet, and wherein a second side of the moveable element defines a second part of the chamber, the second part of the chamber in pressure transmitting relation with the pump outlet, whereby the pressure difference causes the moveable element to translate within the chamber.

16. The apparatus of claim 15 further comprising a spring disposed within the first part of the chamber so as to provide a shut off bias of the flow restricting element.

17. The apparatus of claim 15 wherein the moveable element is a diaphragm mounted within the chamber.

18. The apparatus of claim 17 wherein the flow restrictor is a ball valve having a ball and the diaphragm bears on the ball so that a cracking pressure of the ball valve is increased in proportion to the pressure difference.

19. The apparatus of claim 18 further comprising a spring disposed between the ball and the diaphragm whereby an initial cracking pressure of the ball valve is determined by the spring.

20. The apparatus of claim 15 wherein the moveable element is a piston slidably mounted within the chamber.

21. An apparatus for reducing free flow risk through a pump having a pump inlet and a pump outlet comprising:

means for sensing a pressure difference between the pump inlet and the pump outlet;

means for mechanically communicating the sensed pressure difference to a flow restricting element at the pump outlet; and

means for increasing a resistance to flow exiting the pump outlet through the flow restricting element responsive to the means for mechanically communicating the sensed pressure different so as to increase the resistance when the inlet pressure exceeds the outlet pressure.