초록 ▼

The present invention provides a speed governor (5) suitable for use in a fluid driven down-hole tool (3). The speed governor comprises an actuator (7) operatively coupled to a motive fluid flow control valve (6). The actuator is and arranged so as to be activatable, directly or indirectly, in respo

The present invention provides a speed governor (5) suitable for use in a fluid driven down-hole tool (3). The speed governor comprises an actuator (7) operatively coupled to a motive fluid flow control valve (6). The actuator is and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool (3), for opening of the control valve (6) with increasing rotational speed of the motor (3) above a predetermined speed limit thereby to limit the rotational speed of the downhole tool (3).

대표청구항 ▼

1. A speed governor suitable for use with a fluid driven downhole tool wherein said speed governor comprises an actuator operatively coupled to a motive fluid flow control valve, said actuator being formed and arranged so as to be activatable, directly or indirectly, in response to the running speed

1. A speed governor suitable for use with a fluid driven downhole tool wherein said speed governor comprises an actuator operatively coupled to a motive fluid flow control valve, said actuator being formed and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool in use of said speed governor, said fluid flow control valve comprising a flow restriction valve formed and arranged for restricting motive fluid flow to said fluid driven downhole tool so that fluid flow through any downhole tool downstream of the fluid driven downhole tool is also restricted, wherein said actuator is provided with a resilient biasing device formed and arranged for, directly or indirectly, biasing said flow restriction valve away from a position for restricting motive fluid flow to said fluid drive, and wherein said actuator has at least one first displacement member, formed and arranged so as to be displaceable radially outwardly under the influence of centrifugal forces, directly or indirectly against the return force of said resilient biasing device.2. A speed governor as claimed in claim 1 wherein said control valve comprises a pressure balanced control valve.3. A speed governor as claimed in claim 2 wherein said control valve has a valve member, which valve member is provided with a pressure balancing passage providing fluid communication between opposed sides of said valve member.4. A speed governor as claimed in claim 1 wherein said flow restriction valve comprises a throttle valve.5. A speed governor as claimed in claim 1 wherein said flow restriction valve comprises a bypass valve formed and arranged for diverting at least part of the motive fluid flow away from the fluid inlet of said fluid driven downhole tool.6. A speed governor as claimed in claim 1 wherein said flow restriction valve comprises a dump valve formed and arranged for diverting at least part of the motive fluid flow to the exterior of said fluid driven downhole tool.7. A speed governor according to claim 1 wherein said at least one first displacement member is drivingly coupled to at least one second displacement member for axial displacement of said at least one second displacement member by said at least one first displacement member.8. A speed governor according to claim 7 wherein said at least one first displacement member comprises a discrete mass element in camming inter-engagement with opposed cam surfaces provided on at least one of a respective said at least one second displacement member and a member opposed thereto.9. A speed governor according claim 8 wherein said opposed cam surfaces have a combined slope angle in the range from 10 to 60 degrees in a radially inward direction.10. A speed governor according to claim 8 wherein at least one of said cam surfaces has a cam surface portion with a substantially rectilinear cam surface profile.11. A speed governor according to claim 8 wherein at least one of said cam surfaces includes at least one curved cam surface profile portion.12. A speed governor according to claim 7 wherein said at least one first displacement member is pivotally linked to a respective said at least one second displacement member.13. A speed governor according to claim 12 wherein said at least one first displacement member is formed and arranged for camming inter-engagement with a cam surface provided on a member opposed to said at least one second displacement member.14. A speed governor according to claim 1 wherein said resilient biasing device has a predetermined pre-loading corresponding to a predetermined threshold downhole tool rotary component speed.15. A speed governor system according to claim 14 wherein said resilient biasing device has a pre-loading corresponding to a threshold circumferential speed of said rotary component in the range from 30 to 55 meters/sec, for use with a turbine motor.16. A speed governor according to claim 14 wherein said resilient biasing device has a spring rate for providing a progressive actuator displacement to provide a progressive opening of the control valve between fully closed and fully open position thereof over a rotor speed range which is from 5 to 20% of said threshold speed.17. A speed governor according to claim 14 wherein said resilient biasing device has a variable spring rate for providing an actuator displacement rate which has a variable relation to rotary component speed increase.18. A speed governor according to claim 1 wherein is provided an anti-hunting device.19. A speed governor according to claim 18 wherein said anti-hunting device includes at least one of a viscous damping and frictional element, formed and arranged for resisting and delaying displacement of an actuator displacement member.20. A speed governor suitable for use with a fluid driven downhole tool wherein said speed governor comprises an actuator operatively coupled to a motive fluid flow control valve, said actuator being formed and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool in use of said speed governor, said fluid flow control valve comprising a flow restriction valve formed and arranged for restricting motive fluid flow to said fluid driven downhole tool so that fluid flow through any downhole tool downstream of the fluid driven downhole tool is also restricted, wherein said control valve comprises a main control valve and a pilot control valve for facilitating opening of the main control valve.21. A speed governor suitable for use with a fluid driven downhole tool wherein said speed governor comprises an actuator operatively coupled to a motive fluid flow control valve, said actuator being formed and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool in use of said speed governor, said fluid flow control valve comprising a flow restriction valve formed and arranged for restricting motive fluid flow to said fluid driven downhole tool so that fluid flow through any downhole tool downstream of the fluid driven downhole tool is also restricted, wherein the control valve comprises a sleeve valve comprising a reciprocatingly displaceable sleeve provided with one or more ports which can be brought into and out of register with a corresponding port in a sleeve mounting tube.22. A speed governor suitable for use with a fluid driven downhole tool wherein said speed governor comprises an actuator operatively coupled to a motive fluid flow control valve, said actuator being formed and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool in use of said speed governor, said fluid flow control valve comprising a flow restriction valve formed and arranged for restricting motive fluid flow to said fluid driven downhole tool so that fluid flow through any downhole tool downstream of the fluid driven downhole tool is also restricted, wherein the control valve comprises a reciprocatingly displaceable sleeve having a valve face extending transversely to the axis of motion, for engagement with a valve seat for closing at least one port in the housing.23. A speed governor suitable for use with a fluid driven downhole tool wherein said speed governor comprises an actuator operatively coupled to a motive fluid flow control valve, said actuator being formed and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool in use of said speed governor, said fluid flow control valve comprising a flow restriction valve formed and arranged for restricting motive fluid flow to said fluid driven downhole tool so that fluid flow through any downhole tool downstream of the fluid driven downhole tool is also restricted, wherein said actuator comprises a housing mounting a first support member and a second support member displaceable relative to said first support member, said first and second support members being provided with opposed cam surfaces and with resilient biasing means formed and arranged for biasing said support members with said cam surfaces towards each other, and at least one discrete mass element supported between said cam surfaces in engagement therewith, said cam surfaces converging towards each other in a radially outward direction so that forcing together of said first and second members by said biasing means urges said at least one mass element radially inwardly, whereby when said actuator is subjected to increasing rotational speed, in use thereof, said at least one mass element is subjected to increased centrifugal forces which tend to drive said first and second support members away from each other.24. A downhole motor provided with a speed governor suitable for use with a fluid driven downhole tool wherein said speed governor comprises an actuator operatively coupled to a motive fluid flow control valve, said actuator being formed and arranged so as to be activatable, directly or indirectly, in response to the running speed of the tool in use of said speed governor, said fluid flow control valve comprising a flow restriction valve formed and arranged for restricting motive fluid flow to said fluid driven downhole tool so that fluid flow through any downhole tool downstream of the fluid driven downhole tool is also restricted, wherein the speed governor control valve is a dump valve connected to at least one vent passage having at least one exhaust port at an upstream side of a motor drive fluid supply passage filter for flushing out particulates trapped by said filter whereby, in use of said motor, said filter can be cleared by removing load from said motor so as to allow said motor to speed up sufficiently to cause said speed governor to open said dump valve, thereby to clear said filter.25. A downhole motor according to claim 24 which is a turbine.26. A downhole motor according to claim 24 which is a positive displacement motor.27. A downhole motor according to claim 24 wherein the at least one vent passage is provided with a rearwardly angled exhaust port so as to be directed away from the downhole-direction in use of the speed governor.28. A speed governor suitable for use in a fluid driven down-hole motor which has a rotor, for controlling motive fluid supply to said motor by means of a motive fluid dump valve, said governor comprising an actuator for said dump valve which actuator is formed and arranged for driven coupling to said motor rotor in use of the governor, said actuator comprising a housing mounting a first support member and a second support member displaceable relative to said first support member, said first and second support members being provided with opposed cam surfaces and with resilient biasing means formed and arranged for biasing said support members with said cam surfaces towards each other, and at least one discrete mass element supported between said cam surfaces in engagement therewith, said cam surfaces converging towards each other in a radially outward direction so that forcing together of said first and second members by said biasing means urges said at least one mass element radially inwardly, whereby when said actuator is subjected to increasing rotational speed, in use thereof, said at least one mass element is subjected to increased centrifugal forces which tend to drive said first and second support members away from each other, said second support member being coupled to said dump valve for opening thereof when said second support member is driven away from said first support member by said mass element with increasing rotational speed of the motor above a predetermined speed limit.29. A downhole motor provided with a speed governor according to claim 28.