PIPE TRAVELLING APPARATUS WITH ALIGNMENT CONTROL

Abstract

A conduit travelling apparatus is capable of crawling through a conduit for performing certain operation by a stepwise sequence of alternating sequences of expanding and contracting the length of the body while bracing each end alternately. The apparatus provides a self aligning element for correcting rotation of such apparatus due to powered operations it may perform, or any natural tendency to twist as it progresses. The self aligning element includes steering elements overseen by a control system which helps return the travelling apparatus to a preferred alignment during its forward or rearward travel.

Description

TECHNICAL FIELD

The invention relates generally to self-propelled vehicles for use in conduits, typically remote-controlled vehicles with apparatus for cleaning conduits. In particular it addresses issues of rotation of the apparatus as it travels along a conduit.

BACKGROUND ART

The applicant has previously filed patent applications (WO 2005/061944 A1—PCT/NZ2004/000330) for self propelled apparatus which travels along a pipe. In summary this apparatus comprises a forward section, and a rearward section, connected in a manner in which the two sections can be forced apart or drawn together. Movement along a conduit is achieved by extending clamping elements on the rearward section to engage the inner surface of the conduit. Clamps present on the forward section are released and the connection between the sections is extended so the forward section moves forward. The clamps on the forward section are then engaged against the inner surface of the conduit, whilst those of the rearward section are released. The connection between the sections is then contracted and the rearward section is drawn forward, whereupon its clamps may be re-extended to engage the inner surface of the conduit. Once the vehicle is so secured (i.e. clamped) various operations—such as rotary cleaning on the inside of the conduit—may commence.

In addition the pipe traveller typically has wheel sets on each section which engage the inner walls of the conduit as the clamping elements of a section are withdrawn from the conduit walls. This helps to keep the apparatus centred, whilst the wheels also facilitate smooth movement along the conduit as each section moves therealong.

In practice it has been noted that a problem can occur during operation and travel of the apparatus along a conduit. This problem relates to rotation of the pipe-travelling apparatus about its long axis as it travels. The consequence of such rotation is that it can affect the operation or performance of certain attached accessories and equipment if the pipe-travelling apparatus is no longer in a preferred level position. For instance, waste slurry and cleaning liquid may be collected (for waste or recycling) by a suction mouth which is typically located at the bottom of the pipe travelling apparatus. Rotation of the pipe travelling apparatus can therefore interfere with its operation.

Rotation can also cause other issues, such as the twisting together of cables and lines which can trail the apparatus—such lines may carry electronic information, control data, video signals, electrical power, hydraulic fluid, etc. Twisting of the lines about each other can cause problems such as potential damage to, or constriction of, lines. Additionally, twisting the lines about each other stiffens the bundle making it less flexible and harder for the apparatus to draw around curves and bends in the conduit.

Research by the applicant has confirmed that this rotation can be a natural consequence of the travel of the apparatus along a conduit. Minor obstructions or irregularities in the conduit can bias the apparatus to rotate relative to the conduit as it travels. Minor variations in the action of moving components, especially over time, can also contribute to such rotation—in the same manner that most people lost in a forest will walk in a circle (due to one leg being naturally slightly shorter than the other) even though they believe they are walking in a straight line.

However, one of the greatest effects is a consequence of the action of certain accessories on typical embodiments of pipe travelling apparatus, notably those which are rotational in action. The best demonstrative example is a rotating cleaning head assembly, the rotational axis thereof being the same as that of the pipe travelling apparatus. Such apparatus is typically stopped (or substantially slowed) as the apparatus moves forward, and restarted when the apparatus is stopped and clamped in its new position. Most of these units have reasonable inertia, and sufficiently high rotational momentum when operating that they apply a significant rotational force to the pipe travelling apparatus when they are started. This back force is sufficient to cause some rotation of the pipe travelling apparatus about its long axis, the degree of this effect being determined largely by how well the pipe travelling apparatus is clamped against the inside of the conduit, this in turn being affected by factors such as irregularities and contaminants on the inside of the conduit; soiling of the clamping elements by continued use or by travel through the conduit; fluids present in the conduit, and so on.

Accordingly there is a real problem which can affect the performance and operation of pipe travelling apparatus, particularly of the type described above.

Accordingly it is an object of the present invention to consider the foregoing problems and address rotational issues during the travel and/or use of pipe travelling apparatus within a conduit.

At the very least, it is an object of the present invention to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF THE INVENTION

According to one aspect of the present invention there is provided conduit travelling apparatus for travelling through a conduit, said conduit travelling apparatus comprising two travelling body portions, each with associated wall engaging clamping means, and said travelling body portions connected by extensible drive means capable of moving said travelling body portions towards and away from each other;

• • at least one said travelling body portion including at least one steerable contact portion which can be brought to bear against the inside of a conduit as the travelling body portion moves with respect to the conduit;
  • a said steerable contact portion including at least one conduit engaging element for contacting an inner surface of said conduit;
  • the arrangement being such that said conduit engaging element can exert a steering force against said inner surface of the conduit when its carriage portion bears against and travels along same;

the conduit travelling apparatus also including and/or communicable with inclination and orientation control means comprising inclination determining means, for determining the rotational inclination of the conduit travelling apparatus;

said inclination and orientation control means consequently controlling one or more said steerable contact portions associate with the conduit travelling apparatus.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, having an extensible body in which:

said two travelling body portions comprise a forward body portion and a rearward body portion separated by a powered telescoping connection of variable and controllable length, the powered telescoping connection characterized that the distance between said forward and rearward body portions is controllably alterable;

each of said forward body portion and rearward body portion including a wall-engaging mechanism;

each wall engaging mechanism comprising a plurality of radially pivotable legs, each connected to a said body portion at one end and having a wall-engaging foot at the distal end;

for each wall engaging mechanism, all of the radially pivotable legs with wall engaging feet connecting to a common actuator, said common actuator controlling the radially extended position of said radially pivotable legs between retracted and extended positions;

the wall engaging mechanism on either or both of said forward and rearward body portions including at least one retractable wheel arrangement, a said retractable wheel arrangement comprising a plurality of wall engageable wheel assemblies each coupled to a radially pivoting wheel bracket;

said radially pivotable legs and said radially pivoting wheel brackets of a wall engaging mechanism coupled, the coupling preventing both of i) said radially pivotable legs and ii) said radially pivoting wheel brackets being simultaneously in a fully radially extended position.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which there is inclination determining means associated with each travelling body portion.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the inclination and orientation control means determines the rotational inclination of the conduit travelling apparatus relative to one or more preferred reference orientations.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the inclination and orientation control means determines the steering action required to correct the rotational inclination of the conduit travelling apparatus towards a preferred rotational inclination.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which there is controllable steering drive means associated with a steerable contact portion.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the steering drive means is driven by one or methods in the following list: hydraulically powered, electrically powered, and pneumatically powered.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which a conduit engaging element is pivotably connected the steerable contact portion, to provide a steering action.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the steerable contact portion comprises a carriage.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the steerable contact portion is pivotably connected to the travelling body portion so as to provide a steering action.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which a conduit engaging element comprises one or more members for the following list: wheels, rollers, rotating track assemblies, and skids.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the inclination and orientation control means continuously or repetitively adjusts the degree of steering of a steerable contact portion during motion of a travelling body portion.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which either or both a steerable contact portion and conduit engaging element is retractable so as to not engage an inner surface of said conduit.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the pressure by which a conduit engaging element bears against an inner surface of the conduit can be varied.

According to another aspect of the present invention there is provided conduit travelling apparatus, substantially as described above, in which the inclination and orientation control means adjusts the pressure by which a conduit engaging element bears against an inner surface of the conduit as part of its control over the steering and changing of the inclination of a travelling body portion.

Typically the conduit travelling apparatus may be of a type similar to that disclosed in the applicant's earlier application—WO 2005/061944 A1—PCT/NZ2004/000330. For simplicity of description, the present invention will be described with reference to the machine described in that application, though may be applied to travelling devices of different specific design.

The travelling body portions of the present invention relate to the forward and rearward portions of the earlier device, while the extensible drive means of the present invention is equivalent to the extensible means of the earlier device.

As for the earlier device, each travelling body portion includes a clamping arrangement essentially comprising a plurality of arms with wall contacting feet on each. Preferably these feet have a reasonably high coefficient of friction when pressured against the wall, as they serve to hold the apparatus in place when certain operations (such as cleaning) are performed, as well as bracing the travelling body portion while the other moves forwardly.

In the previous device each travelling body portion included wheels which could bear against the inner wall/surface of the conduit when the wall contacting feet were retracted. The present invention also relies on conduit engaging elements which bear against the inner surface of the conduit when the wall contacting feet are withdrawn, though these conduit engaging elements need not be wheels—they may comprise one or more of any of a set of engaging elements comprising: wheels, rollers, skids, and continuous tracks (e.g. as used on tracked vehicles such as bulldozers).

A primary difference between the present and previous invention is that the conduit engaging elements of the present invention can apply a steering force to the conduit's surface as they travel along same. This steering force can be used to steer the travelling body portions as they move along a conduit. As there is limited scope for movement within a circular conduit, the preferred consequence of the steering effect is to realign the conduit travelling apparatus to its normal or a preferred orientation.

To effect this, inclination and orientation control means is also used, this typically comprising one or more inclinometers or other devices providing information about the rotational orientation of the conduit travelling apparatus. This orientation may be determined in relation to true horizontal (this being perpendicular to the force of gravity), a true vertical (this being substantially the direction of gravitational force), to a reference point in the circumference of the pipe, or to some other reference point—in a vertical conduit the inclination and orientation control means may orientate itself with respect to the magnetic poles or some other signal—including GPS data. In any event, the inclination and orientation control means can determine the deviation in inclination or rotation of the conduit travelling apparatus (or part thereof) from a comparison or reference value. Various forms of inclinometers and directional sensors may be used, including those utilising a gyroscope as a reference comparison point.

The inclination and orientation control means will ideally then determine what direction and degree of steering action, by one or more conduit engaging elements, is required to allow the conduit travelling apparatus (or part thereof) to attain the desired inclination within the conduit. This may be calculated in relation to the distance to be travelled—either in a single step forward, or over several—the latter may be preferred when it is known the device is to move forward by several steps.

To achieve this, typically the steering is achieved by one or more steerable contact portions (typically on a travelling body portion) which in turn include one or more conduit engaging elements. Steering control is ideally powered, some options including hydraulic, pneumatic, and electrically powered mechanisms. Hence, the inclination and orientation control means can then control the degree of steering direction and/or force acting on the conduit's surface by a conduit engaging element.

In the situation where there are multiple conduit engaging elements, and/or multiple steerable contact portions, independent control over the steering action of each element and/or contact portion may be provided for. However, where there are multiple elements and/or contact portions associated with a travelling body portion, it is envisaged that the simpler concept of controlling each of these equivalently (i.e. synchronised with each other) will be preferred—e.g. each contacting wheel in a body portion steers in the same direction by substantially the same amount.

As can be envisaged, various steering strategies can be employed to align/re-align conduit travelling apparatus.

The steerable contact portion may take many forms. Typically the steerable contact portion comprises a carriage which supports one or more conduit engaging elements. Conduit engaging elements may be steerable with respect to the carriage. The carriage/steerable contact portion may be steerable with respect to the travelling body portion with which it is associated. Various combination of the carriage, and the conduit engaging elements, may be steerable or fixed—so long as the a steering force can be applied to the inner surface of the conduit as the steerable contact portion moves along the conduit.

The steerable contact portion(s) may be affixed directly to the body structure of the travelling body portion, or mounted on an arm whose orientation or length (etc.) can be altered to bring the steerable contact portion into contact with the inner surface of the conduit.

While provision may be made for the steerable contact portion(s) and/or conduit engaging element(s) to be withdrawn from contact with the inner surface of the conduit, some embodiments of conduit travelling portions may have one or more conduit engaging elements in contact with the inner surface of the conduit at all times. Typically, however, the arrangement should allow for the conduit engaging elements to accommodate irregularities and features which may be present on the inner surface of a conduit as they travel therealong.

Aspects of the present invention will now be described by way of example only with respect to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from the following description which is given by way of example only:

FIG. 1 is a pictorial view of a first embodiment of the vehicle of the applicant's previous application:

FIG. 2 is a detail of the forward member of the vehicle of FIG. 1;

FIGS. 3a and 3b are details of the rearward member of the vehicle of FIG. 1, and

FIG. 4 is a pictorial view of a second embodiment of the vehicle of the applicant's prior application;

FIG. 5 is a pictorial view of a wall engaging mechanism of the vehicle of FIG. 4;

FIG. 6 is a longitudinal cross-sectional view of a wall engaging mechanism of the vehicle of FIG. 4;

FIG. 7 is longitudinal cross-sectional view of the vehicle of FIG. 4;

FIG. 8 is a side view of the vehicle of FIG. 4 shown exploded,

FIG. 9 is a perspective view of an embodiment of a steerable contact portion according to the present invention,

FIG. 10 is a side diagrammatic view of an alternative embodiment of a carriage portion according to the present invention, and

FIG. 11 is a schematic view of a preferred embodiment of a control system according to the present invention

BEST MODES FOR CARRYING OUT THE INVENTION

Reference will be made, by way of example only to the travelling apparatus of the applicant's previous patent application. This vehicle will be used as a reference vehicle to illustrate the principles of the present invention.

FIG. 1 illustrates an embodiment of conduit travelling apparatus fitted with conduit cleaning apparatus. The apparatus generally comprises a forward travelling body portion 1 mounted to a hydraulic cylinder 2 which represents the extensible drive means. Also present, mounted distally to the cylinder 2 is a rearward travelling body portion 3. A power actuated wall-engaging arrangement (described further with reference to FIGS. 2, 3a and 3b) is provided on both the forward and rearward body portions 1 and 3 for extending and retracting feet 5′ and 5 respectively for selectively engaging the inner wall of a conduit 14 (see FIG. 2) to hold the body portions (1, 3) stationary. By coordinating the engagement and disengagement of the feet 5, 5′ with the movement of the forward and rearward members 1, 3 by the hydraulic cylinder 2 and rod 4, the apparatus may propel itself through the conduit 14 in either direction in a stepwise manner.

A rotary cutter or abrasive assembly 6 is mounted at the front of the forward body portion 1 for loosening material so as to clear or clean the conduit 14. For removing the loosened material a vacuum is drawn through an evacuation tube (not shown) drawn behind the vehicle and connected to the outlet pipe 9 on the forward body portion 1 which draws in the material through the opening 8 formed at the base of the plate 25. Typically the suction opening 8 is located at the bottom of the conduit travelling apparatus, and thus it is desirable that the rotational orientation of the conduit travelling apparatus remains such that opening 8 is always present at the bottom of the conduit.

Referring to FIGS. 1 and 2, the wall-engaging arrangement 50 on the rearward body portion 3 includes three legs 10 to which respective feet 5 are pivotably fixed. Each leg 10 extends generally radially and is fixed by pins 11 for pivoting movement between a retracted position (FIG. 2) and an outwardly extended position (shown in dashed outline in FIG. 2) for engagement with the wall of the conduit 14. A spring 12 for biasing the legs 10 to the retracted position and a linear actuator 13 for extending the legs contact opposing sides of a radially inner end of each leg 10. Hydraulic fluid is supplied to the actuator 13 through the flexible hose coil 15 extending from the forward body portion 1. In the extended position it will be understood that the force F applied to the rearward body portion 3 (e.g. when the forward body portion 1 is being driven forward) provides a self-servo action increasing the frictional engagement between each foot 5 and the conduit 14.

FIGS. 3a and 3b show the wall-engaging arrangement 20 provided for extending the feet 5′ on the forward body portion 1 while simultaneously retracting the wheels 17 (see also later), and vice versa. The three feet 5′ are angularly evenly spaced about the cylinder 2 and are each pivotally mounted on radially extending pivoting legs 18. Associated with each of the legs 18 is a pivoting wheel bracket 19 (lying generally in the same radial plane as the respective arm 18) to which a pair of wheels 17 are fixed to support the forward body portion 1 when the forward set of feet 5′ are retracted. The mechanism 20 is actuated by a hydraulic ram 21 having an annular piston 22 ringing the cylinder 2 and fixed thereto for sliding relative to a cylindrical sleeve 23. Pressurising the hydraulic fluid on either side of the piston 22 displaces the cylindrical sleeve 23 up or down the cylinder 2 for extending and retracting the feet 5′ and wheels 17. The wall-engaging arrangement 20 includes a yoke 35 pivotally connecting each leg 18 and wheel bracket 19. A fork 36 pivotally connects the yoke 35 and the cylindrical sleeve 23.

Water jets 33 extending from the plate 25 direct a water spray (not shown) at the cutter blade 34 for lubrication, cleaning and aiding removal of the loosened material. Water is supplied to the forward body portion 1 in a hose (not shown). The apparatus is connected by control cables (not shown) to a remote controller (not shown) connected to the valve block 38 which incorporates the control valves governing each operation of the apparatus. Together with the control cables, water hose and evacuation tube, elongate hydraulic supply and return lines, (not shown) are bundled together to form an umbilical drawn behind the vehicle and connected to a remote power source and controller (not shown). Preferably programmable-logic-controllers are used in the controller to control each of the operations of the apparatus.

In operation, the apparatus may be stepped through the conduit 14 drawing the hydraulic lines and cables etc behind it until it reaches an obstruction.

With the front set of feet 5′ retracted and the wheels 17 extended to engage the wall of the conduit 14, the actuator 13 is operated to lock the rearward body portion 3 in position. The end of the cylinder 2 opposing the rod 4 is then pressurised to extend the rod 4 and drive the forward body portion 1 in the forward direction.

The hydraulic ram 21 is operated to fix the forward body portion 1, retracting the wheels 17 and extending the front set of feet 5′. When the rearward body portion 3 is released a return spring (not shown) retracts the rod 4 (or, in a double-acting arrangement the rod end of the cylinder 2 is then pressurized to retract the rod 4) to draw the rearward body portion 3 in the forward direction.

The valve block 38 includes control valves (not shown) for automatically reversing the direction of travel of the rod 4 when it reaches the end of its stroke for controlling its reciprocating movement. Solenoid operated valves (not shown) control operation of the rams 13 and 21 for selectively engaging the feet 5, 5′, the timing of which in cooperation with the reciprocation of the rod 4, controls the direction of travel.

When an obstruction is reached, the rearward body portion 3 is fixed and with the wheels 17 extended the cutter 6 is driven forward to loosen and remove the material encountered. A pressure sensing valve (not shown) reacts to an increase in pressure at the hydraulic motor 7, to reduce the rate at which the cutter 6 is advanced. The apparatus can be removed from the conduit by reversing the stepwise mode of travel described above.

A second embodiment of the vehicle is illustrated in FIGS. 4-8 and like numerals are used to refer to like components. The wall-engaging arrangement 50a on the rearward body portion 3 is also arranged generally symmetrically about the central elongate axis A of the vehicle, the feet being angularly spaced at 120°. The mechanism 50a extends and retracts the feet 5a generally radially and includes control links 66 for maintaining the wall-engaging face of each foot 5a generally parallel to the wall of the pipe. The wall-engaging arrangement 50a includes three rear legs 10a angularly spaced, each of the legs 10a being fixed between a pair of control links 66 connecting each foot 5a to the rearward body portion 3.

Each leg 10a is pivotally attached to the foot 5a at an outer end by a first pivot 61 and to a mount 62 fixed to the rearward body portion 3 by a second pivot 63. A roller 64 fixed to an inner end of the leg 10a and the three rollers 64 are received between two radially-extending flanges 69a, 69b fixed to the rod 65 of actuator 13 for pivoting the legs 18a about their respective second pivots 63 to extend the feet 5a simultaneously.

Each pair of control links 66 is pivotally attached to the foot 5a at one end by coaxial third pivots 67 and to the mount 62 at an opposite end by coaxial fourth pivots 68, the pivots pivoting about parallel axes.

Hydraulic fluid supply and return hoses 75 are connected between the valve block 38 and the double-acting actuator 13. The hoses 75 pass around a wheel 76 and are tensioned by the gas spring 77. As in the first embodiment, in the extended position the force applied to the rearward body portion 3 (e.g. when the forward body portion 1 is being driven forward) provides a self-servo action increasing the frictional engagement between each foot 5 and the conduit 14.

Like the mechanism 50a, the wall-engaging arrangement 20a on the forward body portion 1 in the second embodiment of the vehicle extends and retracts the feet 5a′ generally radially while employing control links 66a for maintaining the wall-engaging face of feet 5a′ generally parallel to the wall of the pipe. The wheel bracket 19a is pivotably fixed to the mount 62a and resiliently connected to the pivoting legs 18a by means of compression spring 70 and bar 71. In this manner the wheels 17a are firmly pressed against the wall of the pipe when the front feet 5a′ are retracted to centralise the cutter 34 in the pipe and provide a reaction against the torque applied to the cutter 34, while allowing the wheels 17a to ride over small irregularities in the wall of the pipe. The wheel bracket 19b includes opposed plates 72 between which the wheel 17a and one end of the bar 71 are pivotably fixed. The opposing end of the bar 71 is received for sliding in a bush 73 pivotally connected between a pair of legs 18a. The compression spring is received on the bar 71 and captured between the bush 73 and the pivot on the opposing end.

Each leg 18a is pivotally attached to the foot 5a′ at an outer end by a first pivot 61a and to a mount 62a fixed to the forward body portion 1 by a second pivot 63a. Each pair of control links 66a is pivotally attached to the foot 5a′ at one end by coaxial third pivots 67a and to the mount 62a at an opposite end by coaxial fourth pivots 68a, all the pivots 61a, 63a, 67a, 68a pivoting about parallel axes.

The mechanism 50a is actuated by a hydraulic ram 21 having an annular piston 22 ringing the cylinder 2 and fixed thereto for sliding relative to a cylindrical sleeve 23. Pressurising the hydraulic fluid on either side of the piston 22 displaces the cylindrical sleeve 23 up or down the cylinder 2 for extending and retracting the feet 5a′ and wheels 17. The mechanism 50a includes a yoke 35 pivotally connecting each leg 18a and wheel bracket 19a. Three pairs of links 80 pivotally connect the cylindrical sleeve 23 and an inner end of each leg 18a.

As seen in FIGS. 7 and 8, the vacuum pipe 9 comprises a forward section 9a and rearward section 9b slidingly received therein. This telescoping action allows the overall length of the machine to be reduced for ready insertion into manholes, or the like, for access to drains. The wall-engaging arrangement s 20a, 50a are modular units suitable for use in a limited range of pipe diameters and can be readily demounted from the cylinder 2 and rod 4. The front module 81 includes mechanism 50a as well as the motor 7 and attached cutter 34 which is located on a taper 82 and fixed by fasteners (not shown). The rear module 83 includes mechanism 20a connected to plate 84. Tapered portion 84 fixed to the rod 4 locates the plate 84 centrally. Pins 85 on the plate 84 have flat heads received through keyhole-shaped apertures (not shown) to mount the module 83 by a push-and-turn action.

Apparatus of a type suitable for implementation of the present invention has thus far been described by way of example only, along with typical uses for which it may be employed.

FIG. 9 illustrates an embodiment of a steerable contact portion 90 which replaces the wheels 17 and their mounting axle in the previously illustrated embodiments.

The steerable contact portion 90 comprises a carriage portion 91 and carriage support portion 94. The carriage 91 is pivotably mounted to carriage support 94 by pivot pin 95, which allows partial rotation of the carriage portion 91 about the longitudinal axis of this pin 95.

The carriage portion 91 includes a conduit engaging element 92, which comprises a wheel mounted about axle 93. The wheel includes a self-lubricating sealed bearing and an outer tyre portion comprising a mildly compressible gripping material, such as a rubber or plastics material. Treads and other (vehicle) tyre technology may be incorporated on to the wheel 92 and its outer conduit contacting surface.

Steering is effected by a pair of small rams or actuators 96 (only one visible, but they are symmetrically positioned either side of pivot pin 95) which control the rotation of the carriage portion 91 with respect to the carriage support portion 94.

The steerable contact portion 90 replaces the wheels 17 of the previous illustrations. Pivot pin 97 is positioned in place of the axle for wheels 17. An aperture 98 on the underside of the carriage support portion 94 allows for connection of a ram or actuator to allow the steerable contact portion 90 to be raised so that the outer surface of the wheel 92 contacts and bears against the inner surface of a conduit.

A set of operable steerable contact portions may be placed on both the forward and rearward travelling body portions 1, 3.

An inclinometer and/or directional sensor (not shown) (as part of inclination and orientation control means) may be mounted directly to the body of one or both of the travelling body portions 1, 3. The control circuitry for the inclination and orientation control means may be located remotely (with communication by control cables) or mounted securely on the body of the conduit travelling apparatus. It is anticipated that this can be achieved by a simple programmable processor circuit with a set of suitable instructions to control the steering mechanisms of the apparatus. Remotely located control modules may rely on a laptop, pda, or other computing device to process instructions and oversee control of steerable contact portions 90.

FIG. 10 illustrates a variation of a carriage portion 191 which is connected to carriage support portion 194 in the manner of FIG. 9. An actuator 196 is also present, as per the arrangement of FIG. 9, to enable steering control of the carriage 91. A link 201 connects to a pivot pin (not shown but equivalent to pin 95 in FIG. 9) to enable the carriage portion 191 to rotate relative to the carriage support portion 194 and thus provide for steering.

A sub-carriage assembly 202 is pivotably attached 212 to the carriage portion 191. There is a substantially parallel link comprising an actuator 203 pivotably attached (205, 206) at each end to the carriage portion 191 and a subcarriage arm 204 respectively. This allows the subcarriage assembly 202 to be raised and lowered to vary the pressure against the conduit's inner surface 210.

Connected to the subcarriage assembly is a skid 212 with two rollers 214 which are mounted to the skid 212. A spring mounting system (not visible) according to standard techniques may be used for the roller 214 to skid 212 mounts to accommodate irregularities on the inner surface 210 of the conduit.

This arrangement (of FIG. 10) provides an alternative to FIG. 9, also having additional control over the pressure force (governed by actuator 203) of the steering's contact engaging elements (i.e. 212, 214) on the inner surface 210 of the conduit.

This may be coupled to the control means which can monitor the change in inclination relative to distance travelled forward. If the change in inclination does not match what it should be for the steering angle and distance travelled forward, the control means may then do one or more things (depending on the specific embodiment):

• • increase the steering angle (e.g. for embodiments such as shown in FIGS. 9 and 10);
  • increase the pressure of the steering's contact engaging elements against the conduit face to counteract slipping (such as controlling the actuator 203 in embodiments similar to that of FIG. 10, or increasing the pressure via the actuator controlling the legs (19) on which the carriages are mounted).

FIG. 11 illustrates schematically a preferred embodiment of a control system. Here an orientation sensor 220 provides information to a controller 221 about the relative orientation of the apparatus. The controller 221 evaluates this information and determines the degree of steering which needs to be applied during the next step forward in order to bring the pipe travelling apparatus closer to the desired orientation within the conduit. It then controls the steering motors 222, or components responsible for effecting steering.

The controller 221 may also, based on feedback, determine whether additional corrections to either or both steering angle, and pressure 223 of the steering's contact engaging elements are required to effect the degree of correction calculated.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the spirit or scope of the present invention as described herein.

It should also be understood that the term “comprise” where used herein is not to be considered to be used in a limiting sense. Accordingly, ‘comprise’ does not represent nor define an exclusive set of items, but includes the possibility of other components and items being added to the list.

This specification is also based on the understanding of the inventor regarding the prior art. The prior art description should not be regarded as being authoritative disclosure on the true state of the prior art but rather as referencing considerations brought to the mind and attention of the inventor when developing this invention.

Claims

1-17. (canceled)

18. Conduit travelling apparatus for travelling through a conduit, said conduit travelling apparatus comprising two travelling body portions, each with associated wall engaging clamping means, and said travelling body portions connected by extensible drive means capable of moving said travelling body portions towards and away from each other; the arrangement being such that said conduit engaging element can exert a steering force against said inner surface of the conduit when its carriage portion bears against and travels along same;

at least one said travelling body portion including at least one steerable contact portion which can be brought to bear against the inside of a conduit as the travelling body portion moves with respect to the conduit;

a said steerable contact portion including at least one conduit engaging element for contacting an inner surface of said conduit;

the conduit travelling apparatus including and/or communicable with inclination and orientation control means comprising inclination determining means, for determining the rotational inclination of the conduit travelling apparatus;

said inclination and orientation control means consequently controlling one or more said steerable contact portions associated with the conduit travelling apparatus.

19. A conduit travelling vehicle as claimed in claim 18 having an extensible body in which:

said two travelling body portions comprise a forward body portion and a rearward body portion separated by a powered telescoping connection of variable and controllable length, the powered telescoping connection characterized that the distance between said forward and rearward body portions is controllably alterable;

each of said forward body portion and rearward body portion including a wall-engaging mechanism;

each wall engaging mechanism comprising a plurality of radially pivotable legs, each connected to a said body portion at one end and having a wall-engaging foot at the distal end;

for each wall engaging mechanism, all of the radially pivotable legs with wall engaging feet connecting to a common actuator, said common actuator controlling the radially extended position of said radially pivotable legs between retracted and extended positions;

the wall engaging mechanism on either or both of said forward and rearward body portions including at least one retractable wheel arrangement, a said retractable wheel arrangement comprising a plurality of wall engageable wheel assemblies each coupled to a radially pivoting wheel bracket;

said radially pivotable legs and said radially pivoting wheel brackets of a wall engaging mechanism coupled, the coupling preventing both of i) said radially pivotable legs and ii) said radially pivoting wheel brackets being simultaneously in a fully radially extended position.

20. Conduit travelling apparatus as claimed in claim 18 in which there is inclination determining means associated with each said travelling body portion.

21. Conduit travelling apparatus as claimed in claim 18 in which the inclination and orientation control means determines the rotational inclination of the conduit travelling apparatus relative to one or more preferred reference orientations.

22. Conduit travelling apparatus as claimed in claim 21 in which a preferred reference orientation comprises either or both a true horizontal, or a true vertical.

23. Conduit travelling apparatus as claimed in claim 18 in which the inclination and orientation control means determines the steering action required to correct the rotational inclination of the conduit travelling apparatus towards a preferred rotational inclination.

24. Conduit travelling apparatus as claimed in claim 18 in which there is controllable steering drive means associated with a said steerable contact portion.

25. Conduit travelling apparatus as claimed in claim 24 in which a said controllable steering drive means is driven by one or methods in the following list: hydraulically powered, electrically powered, and pneumatically powered.

26. Conduit travelling apparatus as claimed in claim 18 in which a conduit engaging element is pivotably connected to a steerable contact portion, to provide a steering action.

27. Conduit travelling apparatus as claimed in claim 18 in which a steerable contact portion comprises a carriage.

28. Conduit travelling apparatus as claimed in claim 18 in which a steerable contact portion is pivotably connected to a travelling body portion so as to provide a steering action.

29. Conduit travelling apparatus as claimed in claim 18 in which a conduit engaging element comprises one or more members for the following list of engaging elements:

wheels, rollers, rotating track assemblies, and skids.

30. Conduit travelling apparatus as claimed in claim 18 in which the inclination and orientation control means either or both continuously or repetitively adjusts the degree of steering of a steerable contact portion during motion of a travelling body portion.

31. Conduit travelling apparatus as claimed in claim 18 in which either or both of a steerable contact portion and conduit engaging element is retractable so as to not engage an inner surface of said conduit.

32. Conduit travelling apparatus as claimed in claim 18 in which the pressure by which a conduit engaging element bears against an inner surface of the conduit can be varied.

33. Conduit travelling apparatus as claimed in claim 18 in which the inclination and orientation control means adjusts the pressure by which a conduit engaging element bears against an inner surface of the conduit as part of its control over the steering and changing of the inclination of a travelling body portion.