Positive-displacement pump with inlet float chamber

• US 5,527,164 A
• Filed: 12/23/1994
• Issued: 06/18/1996
• Est. Priority Date: 06/07/1990
• Status: Expired due to Term

• Current Assignee: Humanteknik AB
• Original Assignee: Humanteknik AB
• Inventors: Lundback, Stig
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): MCANDREWS JR, ROLAND G
• Application Number:
  US08/364,847
• Time in Patent Office: 543 Days
• Field of Search: 417/480, 417/490, 417/507, 417/508, 417/509, 417/559
• US Class Current: 417/480
• CPC Class Codes: F04B 43/02 having plate-like flexible members, e.g. diaphragms F04B43/14 takes precedence
• CPC Class Codes: Y10T 137/7781 With separate connected fluid reactor surface
• CPC Class Codes: Y10T 137/7835 Valve seating in direction of flow

Abstract

A fluid valve device for on-off control of fluid flow through a passage extending between two fluid ports (12, 15) and including a valve seat (17A) comprises a hollow valve member (21) which is movable into and out of sealing engagement with the valve seat and defines a valve chamber (20). The valve chamber (20) communicates with one of the fluid ports (15) through the valve seat (17A) and is associated with a valve member actuating device (A) which translates the pressure of the fluid received in the valve chamber (20) from an inlet (12/14) for the fluid flow into a force acting on the valve member to displace it relative to the valve seat (17A). The valve member actuating device in one embodiment includes a thrust surface (A) on the valve member (21) which is directed away from the valve seat and forms part of the wall of the valve chamber (20). A second thrust surface (C) on the valve member (21) is directed oppositely and defines a chamber (V) which is isolated from the valve chamber and the flow passage. A positive-displacement pump includes the fluid valve device as an inlet valve for controlling the admission into the pump chamber (20) of the fluid being pumped.

Claims

1. A positive-displacement pump comprising

means defining a pump chamber (20) of variable volume for receiving fluid being pumped,

a pumping mechanism (18,19) including (i) a displacement member (18) which is movable through an ejection stroke to contract the pump chamber and a filling stroke to expand the pump chamber, and (ii) a driving device (19) for repetitively driving the displacement member through the ejection stroke,

an inlet (12,14) opening into the pump chamber,

an inlet valve (16A,17) which is disposed in the inlet and adapted to open and close to allow and prevent, respectively, fluid flow from the inlet into the pump chamber, and

an outlet (15,17) communicating with the pump chamber, characterised in that

the inlet valve (16A,17) includes a valve seat (17A) defining an inlet opening in the inlet (15,17), and a hollow valve member (16A,21) which defines a cavity and has a sealing portion (21A) engageable with the valve seat and which is displaceable towards and away from the valve seat (17A) between an open position with the sealing portion spaced from the valve seat and a closed position with the sealing portion in engagement with the valve seat,

the cavity of the valve member (16A,21) forms part of the pump chamber (20) and communicates with the inlet opening through a valve member opening surrounded by the sealing portion (21A), and

a valve member actuating means (A) is associated with the pump chamber (20) for translating the pressure of fluid received in the pump chamber from the inlet (12/14) into a force which is applied to the valve member (16A,21) to displace it relative to the valve seat (17A).

2. A positive-displacement pump according to claim 1, characterised in that the valve member (16A,21) includes a first thrust surface (A) facing away from the valve seat (17A) and forming part of the wall of the valve member cavity, whereby the pressure of the fluid received in the pump chamber applies a force to the thrust surface which tends to displace the valve member.

3. A positive-displacement pump according to claim 2, characterised in that the valve member (16A,21) has a third thrust surface (B) which in the closed position of the valve member is situated on the upstream side av the pump chamber (20).

4. A positive-displacement pump according to claim 2, characterised in that the valve member (16A,21) has a second thrust surface (C) which is opposed to the first thrust surface (A) and defines a space (V) which is isolated from the pump chamber (20).

5. A positive-displacement pump according to any one of claims 2-4, characterised in that the pump seat (17A) and the sealing portion (21A) of the valve member (16A,21) in the open position of the valve member define between them an inlet gap (23) which extends over the major portion of, and preferably throughout or substantially throughout, the circumference of the sealing portion (21A).

6. A positive-displacement pump according to claim 5, characterised in that the extent of the inlet gap (23) as measured in the direction of flow of the fluid through it is small in relation to the diameter of the valve seat (17A).

7. A positive-displacement pump according to any one of claims 1-4, characterized by a bottom wall (16B) defining a side of the pump chamber (20) remote from the valve seat (17A) and by a lateral pump chamber wall (16A) which is movable relative to the bottom wall towards and away from the valve seat (17A).

8. A positive-displacement pump according to any one of claims 1-4, characterized in that the surface area of a third thrust surface (B) projected on a plane containing the valve seat (17A) is smaller than the corresponding surface area of the first thrust surface (A).

9. A positive-displacement pump according to any one of claims 1-4 characterised in that the pump chamber (20) is defined by a replaceable sac (16) of flexible material, preferably a plastic film.

10. A positive-displacement pump according to claim 11 characterized in that the pump chamber (20) is defined by a replaceable sac (16) of flexible material, preferably a plastic film, and characterised in that the fluid compartment (22) and the pump chamber (20) are defined by integrally made or permanently interconnected sections of the sac (16), the sac having in the region of the transition between the pump chamber and the fluid compartment a waist portion forming part of the sealing portion (21A) of the valve member (16A,21).

11. A positive-displacement pump according to any one of claims 2-4, characterised in that a variable-volume fluid compartment (22), which is expandable in response to inflow of fluid into the inlet (12,14), is provided in the inlet adjacent to and upstream of the valve seat (17A) and the valve member (16A,21) and in the open position of the valve member is in substantially unrestricted communication with the pump chamber (20) over the major portion of, and preferably throughout or substantially throughout, the circumference of the pump chamber.

12. A positive-displacement pump according to claim 11, characterised by a biasing device (24,25) applying a contracting force to the fluid compartment.

13. A positive-displacement pump according to claim 12, characterised in that the contracting force applied by the biasing device (24,25) increases progressively with increasing volume of the fluid compartment (22).

16. A positive-displacement pump according to claim 6, characterised in that the contracting force applied to the fluid compartment (22) by the biasing device (24/25) increases progressively with increasing volume of the fluid compartment.

14. A positive-displacement pump comprising:

means defining a pump chamber (20) of variable volume for receiving fluid being pumped,

a pumping mechanism (18,19) including (i) a displacement member (18) which is repetitively movable through a pumping cycle comprising an ejection stroke to contract the pump chamber and a filling stroke to expand the pump chamber, and (ii) a driving device for driving the displacement member through the ejection stroke,

means defining an inlet (12,14) opening into the pump chamber,

an inlet valve (16A,17) disposed in the inlet and adapted to open to permit substantially unrestricted fluid flow therethrough into the pump chamber and to close to block fluid flow therethrough,

means defining a fluid compartment (22) of variable volume which forms part of the inlet and is expandable in response to inflow to the inlet of fluid being pumped,

means defining an outlet (15,17) communicating with the pump chamber, and

biasing means (24,25) applying a contracting force to the fluid compartment (22),

wherein the means defining the pump chamber (20) includes a circumferentially extending pump chamber wall, wherein the inlet (12,14) opens into the pump chamber over at least a substantial portion of the circumference of the pump chamber wall, and wherein the fluid compartment (22) is circumferentially coextensive with said portion of the circumference of the pump chamber wall.

15. A positive-displacement pump according to claim 14 or 16, characterised in that the biasing device (24/25) includes a movable portion of the wall of the fluid compartment (22) and resilient means acting on the movable wall portion.

17. A positive-displacement pump according to any one of claims 14-16, characterised in that the fluid compartment (22) is annular and encircles the pump chamber (20).

18. A positive-displacement pump according to any one of claims 14-16, characterised in that the inlet (12,14) opens into the pump chamber (20) through an inlet gap (23) defined by a valve seat (17A) of the inlet valve and a valve member (16A,21) which forms part of the wall of the pump chamber (20) and is movable into and out of sealing engagement with the valve seat.