Flow control device and method

1. A fluid flow control device comprising:

a housing defining a fluid inlet and at least one fluid outlet, wherein the fluid inlet has a first fluid pressure P 1 and the fluid outlet has a third fluid pressure P 3 ; and

a primary flow path located inside the housing and communicating with the fluid inlet and the at least one fluid outlet, wherein:

at least one secondary flow path is arranged in fluid communication with the primary flow path;

the secondary flow path comprises a first fluid flow restrictor and a second fluid flow restrictor serving as an inflow port to a chamber and an outflow port from the chamber, respectively;

the first fluid flow restrictor and the second fluid flow restrictor being configured to generate different fluid flow characteristics based on different fluid properties;

the chamber has a second fluid pressure P 2 and includes actuating means that is responsive to restrictor induced fluid pressure changes in the chamber that occurs when a property of the fluid changes;

the actuating means is operatively connected to at least one valve device in the form of a movable member arranged inside the housing between the fluid inlet and the at least one fluid outlet;

the valve device is movable between an open position where the primary flow path is open and a closed position where the primary flow path is closed; and

the valve device is biased towards the open position due to the first fluid pressure P 1 and towards the closed position due to induced fluid pressure changes (ΔP 2 ), and

wherein the first fluid flow restrictor and/or the second fluid flow restrictor is a part of said valve device.

2. The fluid flow control device in accordance with claim 1 , wherein one of the fluid flow restrictors causes a pressure increase in chamber when the flow changes to fluids having an overall viscosity being lower than the initial fluid during use.

3. The fluid flow control device in accordance with claim 1 , wherein the at least one secondary flow path is arranged at least partly parallel to the primary flow path.

4. The fluid flow control device in accordance with claim 1 , wherein the first fluid flow restrictor and the second fluid flow restrictor are configured to impose different fluid flow characteristics based on different fluid properties.

5. The fluid flow control device in accordance with claim 1 , wherein the first fluid flow restrictor is configured to impose substantially laminar flow characteristics on fluid flowing through the restrictor, and the second fluid flow restrictor is configured to impose substantially turbulent flow characteristics on fluid flowing through the restrictor.

6. The fluid flow control device in accordance with claim 1 , wherein the first fluid flow restrictor is configured to impose flow characteristics based on fluid viscosity, and the second fluid flow restrictor is configured to impose flow characteristics based on fluid density.

7. The fluid flow control device in accordance with claim 1 , wherein one of the flow restrictors is at least partly composed of a material causing a pressure change between the upstream and downstream side that is proportional to the overall fluid viscosity during fluid throughput.

8. The fluid flow control device in accordance with claim 7 , wherein the other of the two flow restrictors is constructed to ensure a pressure change between the upstream and downstream side is proportional to the fluid density during fluid throughput.

9. The fluid flow control device in accordance with claim 1 , wherein the valve device is arranged to close the primary flow path.

10. The fluid flow control device in accordance with claim 1 , wherein the valve device comprises a movable piston arranged for sliding movement inside the housing.

11. The fluid flow control device in accordance with claim 1 , further comprising a fluid restrictor element or area configured to progressively choke the flow out of the second fluid restrictor as the valve device is moved towards a closing position.

12. The fluid flow control device in accordance with claim 1 , wherein the valve device comprises a movable body connected via a flexible bellows to the interior walls of the housing.

13. A method of controlling fluid flow through a housing based on changes in fluid properties, wherein a major portion of the fluid flow follows a primary flow path extending from a fluid inlet having a first fluid pressure P 1 to at least one fluid outlet having a third fluid pressure P 3 , the method comprising:

allowing a minor portion flow of the fluid to flow into a secondary flow path, via a first fluid flow restrictor into a chamber having a second fluid pressure P 2 , and further out of the chamber via a second fluid flow restrictor; and

utilizing the restrictor induced pressure change (ΔP 2 ) in the chamber, that occurs when a property of the fluid changes, to operate a valve device in the form of a movable member that closes the flow within the primary flow path during use,

wherein the valve device is movable between an open position at which the primary flow path is open and a closed position at which the primary flow path is closed, and

wherein the valve device is biased towards the open position by the first fluid pressure P 1 and towards the closed position due to the induced fluid pressure changes (ΔP 2 ), and

wherein the first fluid restrictor or the second fluid flow restrictor is a part of said valve device.

14. The method in accordance with claim 13 , wherein the first fluid flow restrictor causes a decrease in the pressure difference across the restrictor when the flow changes from fluid composed of mainly desired phases to fluid composed of mainly undesired phases during use.

15. The method in accordance with claim 13 , further comprising generating a substantially laminar flow by the first fluid flow restrictor, and generating a substantially turbulent flow by the second fluid flow restrictor.