WO2011139158A1

WO2011139158A1 - A brake for an elongate element

Info

Publication number: WO2011139158A1
Application number: PCT/NO2011/000146
Authority: WO
Inventors: John Helvik
Original assignee: C6 Technologies As
Priority date: 2010-05-07
Filing date: 2011-05-05
Publication date: 2011-11-10
Also published as: NO20100666A1

Abstract

A brake for a cable or similar, comprising a first abutment member (40) and a second abutment member (50; 50') which are arranged with an intermediate space for at least a portion of the elongate element. A wedge (30; 30') is arranged in the space and movable between a first position, where the cable (4) is allowed to move in the space, and a second position, where the wedge (30; 30') is forcing the cable (4) against at least a portion of the first abutment member (40), whereby movement of the elongate element is retarded or prevented.

Description

A brake for an elongate element

Field of the invention

The invention relates to brake systems and in particular a brake for an elongate element such as a cable, wire or similar, as defined in the introduction to claim 1.

Background of the invention

In the oil and gas industry, pliable flexible elongate members such as cables, wires, etc., are widely used to control and monitor instruments in subterranean boreholes. Such cables, etc., are typically stored on a spooling unit (reels) and conveyed into the borehole through an injector head.

In certain downhole applications, a composite rod cable is especially beneficial. This type of cable comprises one or more leads (e.g. metal power leads, and fibre- optic leads) embedded in a carbon rod.

In order to control the movement of the cable into the borehole, injector heads are commonly provided with wire (or cable) braking systems. Such prior art brakes are normally gravity operated, in that they comprise a braking shoe which is allowed to fall down and force the cable against a suitable fixed structure, thus providing a braking action determined by the weight and inertia of the braking shoe. The prior art brakes must also be manually reset.

It is therefore a need for a device for better controlling the braking of a cable, wire, or similar, and one which fulfils a function of emergency and parking brake.

The present applicant has devised and embodied this invention to overcome the shortcomings of the prior art and to obtain further advantages. Summary of the invention

The invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention.

It is thus provided a brake for an elongate element, comprising a first abutment member and a second abutment member which are interconnected and arranged with an intermediate space for at least a portion of the elongate element, characterised by a third abutment member arranged in said space and movable between a first position, where the elongate element is allowed to move in the space between first abutment member and the third abutment member, and a second position, where the third abutment member is forcing the elongate element against at least a portion of the first abutment member, whereby movement of the elongate element is retarded or prevented. In one embodiment, the third abutment member is in the second position on one side abutting the first abutment member and on another side is abutting the second abutment member. The brake comprises actuation means for moving the third abutment member within the space.

Preferably the brake comprises retaining-and-release means for holding the third abutment member in the first position and for releasing the third abutment member form the first position based on a control input.

In one embodiment, the actuation means comprises a spring means by which the third abutment member may be moved from the first position to the second position. Preferably, the spring means is biased when the third abutment member is in the first position.

In one embodiment, the first abutment member comprises a belt of a flexible material, rotatably supported on supports and configured to move by interaction with the elongate element, whereby the elongate element and the belt are moving at the same velocity or substantially the same velocity.

In one embodiment, the brake comprises biasing means for biasing the elongate element towards the belt.

In one embodiment, the third abutment member and said space are wedge shaped, and the first position is in a region of the wider portion of the wedge, and the second position is in a region of the narrower portion of the wedge.

In one embodiment, the wedge shape is curved, and the elongate element comprises a cable or a wire.

The invented brake may conveniently be used for a pliable but semi-rigid cable, such as a carbon composite cable.

Brief description of the drawings

These and other characteristics of the invention will be clear from the following description of a preferential form of embodiment, given as a non-restrictive example, with reference to the attached schematic drawings wherein:

Figure 1 is a side view of an embodiment of the brake according to the invention;

Figure 2a is a partly cut-away side view of an embodiment of the brake according to the invention, illustrating the brake in an unlocked position, i.e. not engaging a cable;

Figure 2b is a sectional drawing along the section B-B in figure 2a;

Figure 2c is an enlarged view of the region labelled "C" in figure 2b; Figure 3a is a partly cut-away, side view of an embodiment of the brake according to the invention, illustrating the brake in a locked position, i.e. engaging a cable;

Figure 3b is a sectional drawing along the section A-A in figure 3a;

Figure 3c is an enlarged view of the region labelled "G" in figure 3b;

Figure 4 is a partly cut-away side view of an embodiment of the brake according to the invention, illustrating the brake in an unlocked position, i.e. not engaging a cable, showing the actuator in a loaded state;

Figure 5 is a partly cut-away side view of an embodiment of the brake according to the invention, illustrating the brake in a locked position, i.e. engaging a cable, showing the actuator in an unloaded state;

Figure 6 is a partly cut-away side view of an embodiment of the brake according to the invention, illustrating the brake in an unlocked position, i.e. not engaging a cable, showing the actuator in an unloaded state;

Figure 7 is a partly cut-away side view of an embodiment of the brake according to the invention, illustrating the brake in an unlocked position, i.e. not engaging a cable;

Detailed description of a preferential embodiment

Referring initially to figure 1 , the brake according to the invention comprises in the illustrated embodiment a unit which may be assembled onto an injector head structure 2 (illustrated only partly in the figures) for controlling the movement of a cable 4 into a borehole. Here, the cable 4 is guided into the brake via a bend restrictor 1 , for example of the type which is described in Norwegian patent application No. 20100174, filed on 3 February 2010 by the present applicant. The bend restrictor limits the bending radius of the cable to a pre-determined value.

In the brake, the cable 4 enters a wedge shaped space defined by support element 50 and a cable support member 40. A wedge shaped element 30 is arranged such that it is movable within the space, in a direction generally along the cable. The movement of the wedge 30 is controlled by an actuator 20 and a holding device 6 (these components are described in more detail below, with reference to figures 4 - 6). The cable support member 40, support element 50, actuator 20 and the holding device 6 for the wedge are all assembled on a common frame or structure 3.

Figure 1 furthermore illustrates that the cable support member 40 comprises a curved side 40a and a straight side 40b, and a moving belt 43 surrounding the support member 40 and being rotatably supported by a pair of rollers 42. The curvature of the curved side 40a is corresponding to the curvature of bend restrictor 1. The cable 4 is bearing against the movable belt and there is hence virtually no relative velocity between the belt and the cable; i.e. the two objects are moving at the same speed. Thus, the cable support member 40 provides an almost frictionless support and guide for the cable. An optional supporting roller 51 also assists in holding the cable against the belt. Figure 1 illustrates the brake in a released state, i.e. the cable 4 is allowed to run virtually unimpeded through the brake, from a topsides spooling unit (not shown) and into the injector head 2 and further into the borehole (not shown).

The support element 50, on the other side of the wedge shaped space from the cable support member, constitutes an abutment element for the wedge 30, and has consequently a shape which is complementary to that of the wedge.

The interaction between the wedge 30, cable 4 and support member 40 will now be described with reference to figures 2a-c and 3a-c. In these figures, the wedge actuator is not illustrated; the function of this unit is described below.

Figure 2a illustrated the brake connected to a structure 2a (e.g. the above mentioned injector head) and receiving a cable 4, in a normal mode of operation running in a direction which is from the upper part of the figure to the lower part of the figure. Figure 2a illustrates the brake in a released state, similar to that of figure 1. Figures 2b and 2c illustrates how the cable 4 is being supported by the belt 43 and that there is a distance d (i.e. no contact) between the cable and a friction lining 32 on the wedge 30.

Figures 3a-c correspond to figures 2a-c, but illustrates the brake in a set, or activated, state, where the wedge 30 has been moved to its locking position (i.e. further into the wedge shaped space). The cable 4 is being squeezed between the belt 43 and the friction lining 32, and its movement is hence restricted. If the wedge 30 is moved to this locking position while the cable 4 is moving at a velocity through the brake, the friction force between the lining 32 and the cable will serve to retard the velocity and eventually stop the cable movement. The magnitude of deceleration will depend on the surface roughness of the cable, the quality and state of the friction lining, and the force with which the wedge is being held in the locking position.

The function of the actuator 20 and the holding device 6 will now be described with reference to figures 4, 5 and 6. In these figures, the belt 43 and rollers 42 (cf.

figures 1 - 3c) have been removed. Reference number 44 indicate the roller axles. These figures also show a connection piece 5 for the bend restrictor 1 (cf. figure 1)

The actuator 20 comprises an actuation mechanism of a known type (and therefore not described in detail), e.g. hydraulically or electrically operated. Reference number 23 indicates control and power lines for operation of the actuator. The actuator is assembled onto the frame 3 and drives a rod 22 which extends into a sleeve 33 in the wedge 30 and at its distal end is connected to a retainer disk 24.

Arranged in the sleeve 33, between the retainer disk 24 and the inner portion 31 of the sleeve, is a helical spring 21. The movement (expansion) of the spring 21 is in one direction limited by the retainer disk 24 and in the other direction by the sleeve inner portion 31. A restriction 34 in the sleeve 33 (in the illustrated embodiment at the sleeve opening) is greater than the rod 22 diameter but smaller than the retainer disk 24. The actuator rod may thus reciprocate within the sleeve, by is prevented from being withdrawn form the sleeve because of the interaction between the retainer disk 24 and the restriction 34.

The holding device 6 serves a purpose of holding the wedge 30 in an unlocked position of the brake, while allowing the wedge to be biased by the actuator and spring, and allows a quick release of the wedge based on a control input. In the illustrated embodiment, e.g. in figure 5, the holding device 6 comprises an electromagnet 6b which is assembled onto the frame 3 or an associated structure, and a magnetisable element 6a connected to the wedge 30. When the electromagnet 6b is activated, it holds the magnetisable element 6a - and hence the wedge 30. As soon as the electromagnet 6b is deactivated (e.g. by disconnecting electrical power to the device), the magnetic field deteriorates to such an extent that the

magnetisable element (e.g. a plate, or similar) 6a immediately is disconnected from the electromagnet. It should be understood that although an electromagnetic holding is preferred in this embodiment of the brake, other (e.g. mechanical) holding devices are equally applicable as long as they fulfil the dual function of firm and reliable holding and a quick and controlled release of the wedge.

Figure 4 illustrates the brake in an unlocked (released) position. The holding device 6 is activated, i.e. locking the wedge such that it is not restricting cable movement. The actuator rod 22 is extended, compressing the spring 21. Thus, figure 4 illustrates a stand-by position of the brake. When the holding device 6 is released, the wedge is immediately forced (by the action of the compressed spring) into the wedge shaped space and into a frictional engagement with the cable, as described above.

Figure 5 illustrates the brake in a locked (set) position, i.e. after the holding device has been released. The actuator rod 22 is still extended and the spring 21 has expanded, compared to the compressed state shown in figure 4. The stiffness of the spring 21 may for each application be chosen such that the actuator rod and spring are imparting a desired force onto the wedge 30 when the wedge is in the set position. The force with which the wedge is pressed against the cable may thus be controlled.

In order to release the brake (i.e. unset the wedge), the actuator is operated to retract the rod 22. The actuator rod is thus pulled out of the sleeve 33 until the retainer disk 24 abuts the restriction 34. From this point onwards the continued retraction of the rod 22 effects to withdraw the wedge 30 to its unlocking position. This state is illustrated by figure 6, showing the brake in an unlocked (released) position. The holding device 6 has been activated, locking the wedge so that it is not restraining cable movement. The spring 21 is expanded. In order to re-set the brake to a standby position (as in figure 4), the actuator rod 22 is extended, thus compressing the spring 21.

The invented brake therefore fulfils a function as an emergency brake which may be released quickly and predictably, and also rapidly be re-set to a stand-by position, in addition to its function as a regular operating and parking brake for the cable.

Figure 7 illustrates a variant of the brake, having straight wedge shaped space. This variant may be used in assemblies where the cable 4 enters the brake in a rectilinear path (in the all of the figures, the cable is in the normal operating modes entering the brake in upper part of the drawing, as the skilled person will understand). In this variant, the cable support member 40 has been turned around, compared to the variant described above, such that the straight side 40b is facing the wedge shaped space. The wedge shaped space is furthermore defined by a straight support element 50', and the corresponding wedge 30' also comprises straight sides. Otherwise, the parts and operation of the brake is as per the discussion above, particularly with reference to figures 4 - 6.

Claims

1. A brake for an elongate element (4), comprising

- a first abutment member (40) and a second abutment member (50; 50') which are interconnected and arranged with an intermediate space for at least a portion of the elongate element; characterised by

a third abutment member (30; 30') arranged in said space and movable between

- a first position, where the elongate element (4) is allowed to move in the space between first abutment member (40) and the third abutment member (30; 30'), and

- a second position, where the third abutment member (30; 30') is forcing the elongate element (4) against at least a portion of the first abutment member (40), whereby movement of the elongate element is retarded or prevented.

2. The brake of claim 1 , wherein the third abutment member (30; 30') in the second position on one side is abutting the first abutment member (40) and on another side is abutting the second abutment member (50; 50').

3. The brake of claim 1 or claim 2, further comprising actuation means (20, 21 , 22) for moving the third abutment member (30; 30') within the space.

4. The brake of any one of the preceding claims, further comprising retaining- and-release means (6, 6a,b) for holding the third abutment member (30; 30') in the first position and for releasing the third abutment member form the first position based on a control input.

5. The brake of claim 3 or claim 4, wherein the actuation means comprises a spring means (21) by which the third abutment member (31 ; 30') may be moved from the first position to the second position.

6. The brake of claim 5, wherein the spring means (21 ) is biased when the third abutment member is in the first position.

7. The brake of any one of the preceding claims, wherein the first abutment member (40) comprises a belt (43) of a flexible material, rotatably supported on supports (44) and configured to move by interaction with the elongate element (4), whereby the elongate element and the belt are moving at the same velocity or substantially the same velocity.

8. The brake of claim 7, further comprising biasing means (41 , 51) for biasing the elongate element (4) towards the belt (43).

9. The brake of any one of the preceding claims, wherein the third abutment member (30; 30') and said space are wedge shaped, and the first position is in a region of the wider portion of the wedge, and the second position is in a region of the narrower portion of the wedge.

10. The brake of claim 9, wherein the wedge shape is curved, and the elongate element comprises a cable or a wire.