Pressure control valve

1. A downhole flow system, comprising:

a housing including a bore therethrough, a fluid flow flowing through the bore;

a port directing a portion of the fluid flow to a downhole tool, the downhole tool being operable by the portion of the fluid flow; and

a pressure control valve in the bore, the pressure control valve being located downhole of the port, the pressure control valve including:

a flow restrictor; and

an actuator connected to the flow restrictor, the actuator changing a position of the flow restrictor to adjust a pressure differential uphole of the pressure control valve in response to a change in a property of the fluid flow.

2. The system of claim 1 , the downhole tool including an expandable tool.

3. The system of claim 1 , the flow restrictor including:

a stator across the bore, the stator including an opening; and

a rotor, the rotor selectively blocking the opening.

4. The system of claim 1 , the flow restrictor including:

an orifice having an orifice diameter; and

a restrictor body having a restrictor diameter greater than the orifice diameter, the restrictor body being movable relative to the orifice.

5. The system of claim 1 , the flow restrictor including an adjustable orifice diameter.

6. The system of claim 1 , the actuator changing the position of the flow restrictor between more than two positions.

7. The system of claim 1 , the actuator changing the position continuously between a high pressure position and a low pressure position.

8. The system of claim 1 , the actuator including a linear actuator.

9. The system of claim 1 , an entirety of the fluid flow downhole of the port flowing through the pressure control valve.

10. A The downhole flow system of claim 1 ,

wherein the flow restrictor includes a choke body in the bore, the choke body including an orifice having an orifice diameter less than the bore diameter, the flow restrictor further including a restrictor body having a diameter greater than the orifice diameter; and

wherein the actuator comprises a resilient member urging the choke body toward the restrictor body.

11. The system of claim 10 , the choke body moving in response to the fluid flow.

12. The system of claim 11 , the choke body moving in response to changes in the fluid flow.

13. The system of claim 10 , a restrictor offset between the restrictor body and the choke body being greater than zero when the choke body is in a closed position.

14. The system of claim 10 , the resilient member being a disc spring.

15. A method for controlling pressure at a downhole tool, comprising:

flowing a fluid flow through a bore in a housing, the bore including a pressure control valve, the fluid flow having a first drilling property and a pressure differential uphole of the pressure control valve;

directing a portion of the fluid flow to said downhole tool, the downhole tool being located uphole of the pressure control valve;

changing the first drilling property to a second drilling property; and

adjusting a flow restrictor in the pressure control valve with an actuator in response to changing the first drilling property to the second drilling property, wherein adjusting the flow restrictor maintains the pressure differential above the pressure control valve.

16. The method of claim 15 , wherein changing the first drilling property includes changing a density of the fluid flow.

17. The method of claim 15 , wherein changing the first drilling property includes changing a volumetric flow rate of the fluid flow.

18. The method of claim 15 , wherein adjusting the flow restrictor includes actively adjusting the flow restrictor.

19. The method of claim 18 , wherein actively adjusting the flow restrictor includes measuring the change in the first drilling property.

20. The method of claim 15 , wherein adjusting the flow restrictor includes passively adjusting the flow restrictor.