NL2006995C2 - Sewer cleaning robot having a controllable water jet cutter at an outer end of a moving mechanism. - Google Patents

Description

5

P30578NL00/RR

Title: Sewer cleaning robot having a controllable water jet cutter at an outer end of a moving mechanism.

The present invention relates to the field of sewer cleaning robots with which obstructing objects inside a sewage pipe of a sewer can be cut loose.

Cleaning of sewers from dirt or other kinds of blockings is performed since long by means of spouting water into or through those sewage pipes where the blockages have 10 been detected. This can for example be done by pushing a water hose into and through those pipes while spouting water. Some more difficult to be removed obstructing objects, like thick roots of a tree which have grown into a sewage pipe or hardened pieces of concrete which have penetrated a sewage pipe, however can not be removed in this way. For this sewer cleaning robots have been developed which can be wheeled through the 15 pipes towards the location where the obstructing object is present. Such cleaning robots are equipped with a mill/fraise, drill or grinder with which the object can be cut loose or crumbled into smaller particles such that it can be removed out of the sewer. The robots are connected to a mobile unit above ground by means of a data cable, electricity cable and/or hydraulic or pneumatic pressure hose for feeding its moveable parts with control 20 instructions and energy.

For example WO 93/05334 shows a remote controlled sewer cleaning robot with a video-monitored mill/fraise. In this robot the mill/fraise and a camera are mounted at the outer end of a moving arm construction which is connected to a wheeled transportation unit of the robot by means of swivel and hinge joints. During operation the robot is first driven 25 towards the position where the detected obstructing object is present inside the sewage pipe. Then the mill/fraise is placed against the obstructing object by means of a suitable rotation of the moving arm construction around its swivel and hinge joints. This aligning is monitored by an operator sitting behind a steering unit present inside the mobile unit above ground. The steering unit comprises a monitor offering the operator a view inside the 30 sewage pipe via the camera mounted near the mill/fraise at the outer end of the moving arm construction. Subsequently the operator starts the mill/fraise by having it driven in rotation in order to mill away the obstructing object. During milling the operator needs to closely monitor the milling process in order to be able to keep steering the moving arm such that the mill/fraise remains to stay in direct physical contact with the obstructing object.

35 A disadvantage with those known robots is that their user-friendliness leaves to be desired. For example the milling by the mill/fraise causes dirt to be smashed all around. This -2- troubles the sight of the operator via the camera, particularly because the dirt also gets smashed against the lens of the camera. This problem is partly overcome by having a water nozzle mounted directly underneath the camera lens with which the lens from time to time can be flushed clean during milling. Nevertheless, even then the space around the 5 mill/fraise inside the sewage pipe still remains troubled because of all the dirt particles flying around. Further, it is disadvantageous that the entire robot may start to severely tremble during the milling action because of unevenness of the obstructing object and differing material properties seen over its cross section. This makes it very difficult for the operator to keep the mill/fraise lying against the obstructing object with a desired amount of 10 substantially constant pressing force during the milling. If this is not done accurately enough, this may easily lead to the mill/fraise getting broken because of hard smashes it then may make against the object while being driven in rotation at the same time. It may even be necessary to temper the rotational speed of the mill/fraise when the trembling gets to harsh, which lengthens the time required for the milling. Also the mill/fraise may easily get 15 broken or worn off when the obstructing object is relative hard, for example if concrete has to be removed. A replacement of the mill/fraise is time-consuming because for this the entire robot needs to be retrieved from out of the sewer to a location above ground. Another disadvantage is that in the case of for example thick tree roots growing into the sewer, it is first necessary to remove all the mud and root-hairs from around the thick tree root. This is 20 done by flushing the sewage pipe as clean as possible with water. Also it has proven necessary to firmly press the root tree against the wall of the sewage pipe during milling it through with the mill/fraise in order to prevent the natural fibres of the root to shoot away sideways.

The present invention aims to at least partly overcome one or more of the above 25 disadvantages, or to provide a usable alternative. In particular the invention aims to provide a user and environmental friendly sewer cleaning robot with which a wide variety of obstacles inside sewage pipes can quickly and reliably be removed.

This aim is achieved by means of a sewer cleaning robot according to claim 1. The robot comprises a transportation unit, preferably one having an elongated shape, which has 30 a longitudinal axis extending from a front to back end of the unit, and which has controllable first operating means, for example an electromotor driving a set of wheels carrying the unit, for displacing the transportation unit in its longitudinal direction through a sewage pipe. A swivel head is provided at the front end of the transportation unit. The swivel head has a rotation axis parallel or even equal to the unit’s longitudinal axis and has controllable 35 second operating means, for example an electric motor, for rotating the swivel head around its rotation axis. A moving mechanism is provided which is connected to the swivel head.

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The moving mechanism has an outer end and has controllable third operating means, for example a piston-cylinder organ, for displacing the outer end of the moving mechanism between radial inward and outward positions relative to the unit’s longitudinal axis. At an outer end of the moving mechanism a water jet cutter is provided. The water jet cutter is 5 connected to a water feed and has controllable fourth operating means, for example a pumping unit, for feeding the water jet cutter with pressurized water during a cutting operation. A cutting jet of water can then be ejected from out of a nozzle of the water jet cutter in the direction of the obstructing object.

The nozzle of the water jet cutter has been designed such, for example with an 10 orifice opening of between 0,5-1,5 mm, that it is capable of ejecting a relative sharp jet of water at high enough speed. In this way it is capable of slicing into all kinds of materials of objects obstructing a passageway of a sewage pipe by merely using a jet of water at high enough velocity and pressure without having to physically contact the object. The water jet cutter only uses very little water per minute depending on its nozzle’s orifice size. For 15 example 8 liter per minute may suffice. The water that is used during the cutting can easily be drained off via the sewer.

Advantageously it has appeared in practice that the water jet cutter can for example easily cut through thick roots of trees which have grown into a sewage pipe, and is also well able to cut through relative hard objects like a mass of concrete which has penetrated into a 20 sewage pipe. Those water jet cuts are in no way limited by the thickness of the obstructing objects to be removed.

Surprisingly it has appeared that in the case of having to cut through a root, that this root then did not have to be clamped against the sewage pipe wall during the cutting process. In fact in general no physical contact is necessary between the water jet cutter or 25 any other part of the robot and the obstructing object. An interspacing of up to 200 mm can be kept between the nozzle of the water jet cutter and the obstructing object during cutting. Owing to this possible large interspacing the operator has gotten a much easier job in monitoring the cutting process. The robot no longer needs to be accurately kept with a milling organ like a rotating mill/fraise against the object during cutting, but can be roughly 30 positioned with its nozzle nearby the object. The interspacing between the object and the water jet cutter also has the advantage that the robot does not start to tremble and shake during cutting. Also the water jet cutter does not wear off or gets damaged easily in another manner.

Also it has appeared that far less particles get smashed around during the water jet 35 cutting compared to the milling step according to the already known state of the art. An important benefit of the water jet cutter is its ability to cut the obstructing objects without -4 - interfering with their material's inherent structure. The water jets thus largely prevent airborne particles arising from cutting materials. This greatly improves the work environment. Lenses of cameras mounted at the robot remain cleaner because of this and because of the water which automatically gets sprayed against it during the water jet 5 cutting. With the milling step according to the state of the art any rotational movements of the mill/fraise causes cutting material to be spread all around the mill/fraise, including towards lenses of cameras mounted close thereto. With the water jet cutter according to the invention the jet of water coming out of the nozzle during cutting is mostly directed away from such lenses of cameras. This advantageously causes the cutting material to be forced 10 away from the camera lenses, thus keeping the lenses cleaner. This makes it easier for the operator to monitor, steer and control the cutting process.

Furthermore, the reach of the robot has improved considerably. On the one hand the reach is large owing to the abovementioned possible interspacing. On the other hand the reach can be large since it has become possible to construct the moving mechanism itself 15 relative large/long because the water jet cutter only exerts a small counterforce at it during cutting and because the moving mechanism does not have to be able to deliver a large pressing force against the obstructing object during the cutting. The large reach makes the robot specifically usable in somewhat larger sewage pipes, having diameters of up to 1000mm, but also in specific types of sewage pipes, like for example egg-shaped sewage 20 pipes. It also makes it possible to use the robot for removing obstructions inside sideways extending branch pipes which otherwise could not be reached.

In a preferred embodiment the robot further comprises a further swivel head at the outer end of its moving mechanism. This further swivel head has a rotation axis which is perpendicular to the unit’s longitudinal axis. The nozzle of the water jet cutter can then be 25 mounted to this further swivel head, while at the same time controllable fifth operating means, for example one or more piston-cylinder organs, are provided for rotating the further swivel head with the nozzle around its rotation axis. This makes it possible to steer the nozzle such that it not only gets to be positioned at a desired interspacing from the obstructing object, but that it also can be directed substantially perpendicular to the object. 30 The further swivel head at the outer end of the moving mechanism together with the swivel head and moving mechanism at the front end of the transportation unit even makes it possible to steer the nozzle around the object during water jet cutting while keeping it suitably interspaced and perpendicularly directed relative to the object.

In a further embodiment the nozzle of the water jet cutter is provided at an outer end 35 of a main pipe segment projecting outwardly of the further swivel head and having a length of between 10-200 mm. In addition to or in replacement of this pipe segment, an extension -5- pipe segment may be provided having a length of between 10-200 mm. The main pipe segment and/or extension pipe segment can be used to further improve the reach of the robot, but can also be used to pull an obstructing object out of the sewage pipe, for example by hooking the pipe segment behind the object.

5 In an advantageous embodiment the moving mechanism comprises a moving arm which is connected by means of a hinge joint to the swivel head. The controllable third operating means can then be designed for rotating the arm around its hinge joint between forward and sideways projecting hinge positions relative to the transportation unit. The moving arm is easily manoeuvrable by the operator, is robust and relative invulnerable.

10 During transportation of the unit through the sewer, the arm can be directed forward. During the actual water jet cutting it can be directed sideways as far as is necessary to reach the desired interspacing from the obstructing object.

The moving arm can be given all kinds of lengths, but owing to the reason given above that it no longer needs to be able to withstand large counteracting forces or deliver 15 large pressing forces, it can even be given a length of 500 mm or more.

The water feed preferably comprises a duct which extends through the swivel head and through the hinge joint. Thus it is protected and does not stand in the way of being able to smoothly position the nozzle relative to the object. Further the water feed may comprise a water pressure hose extending between the transportation unit and a pumping unit. This 20 pumping unit can then be placed above ground, for example inside a mobile operating unit like a sewer cleaning vehicle.

The pumping unit preferably is designed for delivering water at a pressure of at least 200 bar to the nozzle, in particular at least 500 bar, more in particular at least 1000 bar, and in the future this may even be increased up to a 2000 bar or more.

25 Further preferred embodiments of the invention are stated in the dependent subclaims.

The invention also relates to a method for removing objects out of a sewage pipe according to claim 10.

30 The invention shall be explained in more detail below with reference to the accompanying drawings, in which:

Fig. 1 shows a perspective view of an embodiment of the sewer cleaning robot according to the invention in its transportation state;

Fig. 2 shows the robot of fig. 1 inside a sewer during cutting of a tree root; 35 Fig. 3 shows a cross section of fig. 2; and

Fig. 4 shows the robot of fig. 1 when cutting away an object inside a branch pipe.

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In fig. 1 the entire robot has been given the reference numeral 1. The robot 1 comprises a transportation unit 2 having a set of wheels 3.The unit 2 comprises a sealed housing inside which an electromotor as drive unit for driving the wheels 3 has been 5 provided. The unit 2 is an elongated partly cylindrical body having a longitudinal axis 4. At the front end of the unit 2, a first swivel head 5 is provided which can be freely rotated around the longitudinal axis 4 infinitely, that is to say over as many full rotations as desired to a desired rotational position. At the first swivel head 5 a moving arm 6 is connected by means of a hinge joint 7 having a hinge axis 7’. A pneumatic cylinder 7a is mounted 10 between the first swivel head 5 and an outer free end 8 of the arm 6 for being able to controllably have the arm 6 rotate over an angle of maximum 90 degrees around its hinge axis 7’ to a desired rotational position. An electromotor as drive unit for rotating the first swivel head 5 is housed inside the unit 2 for this.

At the same outer end 8 of the arm 6, a second swivel head 9 is provided which can 15 rotate around an axis 9’ which extends parallel to the hinge axis 7’ and perpendicular to the longitudinal axis 4. Two proportional pneumatic cylinders 9a are mounted between the second swivel head 9 and the arm 6 for being able to controllably have the second swivel head 9 rotate over an angle of maximum +/- 90 degrees around its axis 9’ to a desired rotational position. The second swivel head 9 is provided with an outwardly projecting pipe 20 segment 10 which ends in a nozzle 11 of a water jet cutter. The pipe segment can have a diameter of between 10-30 mm.

The robot 1 is further equipped with a first camera lens 15 mounted on the first swivel head 5 just above the hinge joint 7, and a second camera lens 16 mounted at the outer end 8 of the arm 6 closely behind the nozzle 11 of the water jet cutter. The second 25 camera lens 16 is mounted rotatable around an axis 16’.

A water feed duct (only a small part of which is shown coming out of the swivel head 5 and denoted therewith the reference numeral 17) extends through the robot 1, starting from a connection nipple 18 at the back end of the unit 2, running along or through the inside of the housing of the unit 2, along or through a centre of the first swivel head 5, along 30 or through the hinge joint 7, along or through the arm 6, and finally along or through the second swivel head 9 to there connect with the pipe segment 10. Preferably the water feed duct extends through the second swivel head 9 in order to not stand in the way of the rotatability of this second swivel head 9 around its axis 9’. Because of the high pressures used, an external duct would be prone to becoming rigid and thus make a rotation of the 35 second swivel head 9 around its axis 9’ more difficult.

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Besides the connection nipple 18, the unit 2 is also provided with a connection for a data cable through which images coming from the cameras 15, 16 can run. Furthermore a connection is provided for an electricity cable for feeding the drive units of the wheels 3 and the first swivel head 5, as well as a connection for a pneumatic hose for feeding the piston-5 cylinders 7a and 9a with compressed air whenever their operation is ordered for by means of a steering signal of an operator.

Fig. 2 shows a sewer with a drain hole 20 giving access to a sewage pipe 21. A cleaning vehicle 22 is positioned above ground near the drain hole 20. Inside the vehicle 22 a control unit for the operator to monitor and steer the robot 1, a battery or generator for 10 feeding the drive units of the wheels 3 and the first swivel head 5 with electricity, a supply of compressed air for feeding the robot 1 with pressurized air, a supply of water and a pumping unit for pumping water at a certain pressure towards the robot 1 are provided. An assembly of a pressure water hose, electricity and data cables and pneumatic hose 23 extends from those parts inside the vehicle 22 towards the robot 1. The robot 1, in the 15 situation as shown in fig. 2, has already been displaced towards an aimed location inside the pipe 21 by means of a suitable driving of the wheels 3. At this aimed location tree roots 24 grow into the pipe 21 which are at least partially blocking the pipe 21. In fig. 2 and in more detail in fig. 3 it can be seen that the arm 6 has been lifted upwards by means of a suitable operating of the pneumatic cylinder 7a. Furthermore the arm has been tilted 20 somewhat by having the first swivel head 5 rotated. In this lifted slightly tilted position the arm 6 has its outer end 8 positioned at a distance of approximately 1-10 cm from the location where one of the tree roots 24 enters the pipe 21. The swivel head 9 has been rotated such that the nozzle 11 is directed substantially perpendicular at the aimed cutting position on the tree root 24. By at the same having the pumping unit transport water at a 25 pressure of 500-1000 bar towards the robot 1, the nozzle 11 starts to eject a sharp jet of water towards the root 24 and cuts right through it. If necessary the operator can keep on steering the second swivel head 9, moving arm 6 and/or first swivel head 5 such that the nozzle 1 maintains being substantially perpendicularly directed with its water jet at the root 24 while the nozzle 11 is being slowly rotated around the aimed cutting position.

30 In fig. 4 the robot 1 is move to a position close to a branch pipe 40 of a sewage pipe 41. The arm 6 is lifted to a position in which the nozzle 11 gets to lie in front of the branch pipe 40. The second swivel head 9 has been rotated such that the nozzle 11 is directed substantially straight towards a dirt blocking 42 inside the branch pipe 40.

Besides the embodiment shown, numerous variants are possible. For example the 35 various parts of the robots may be given different dimensions and/or shapes. Also it is possible to use other kinds of operating means, like for example water hydraulically driven -8- drive units instead of the electromotors and piston cylinder-organs. Valves and other types of control means for the operating means may be integrated in the arm or transportation unit. Instead of the water feed running mostly through the interior of the robot it is also possible to have it run along the outside of its movable parts. Instead of the moving arm 5 construction it is also possible to use other types of operable moving mechanisms like for example a forklift construction. The moving arm or other type of moving mechanism can be mounted such to the swivel head that it can be easily replaced by other types of modules, for example modules comprising a milling device as cutter unit or modules having a carrying piece into which the end of a water hose can be held. Finally it is noted that it is also 10 possible to use a mixture of water and an abrasive substance for feeding the nozzle with in order to slice even harder obstacles inside the sewer. It has to be watched then however not to damage the sewer itself.

Thus according to the invention an elegant small multi-purpose sewer cleaning robot is achieved onto which an multi-axis moveable displacement mechanism carrying a water 15 jet cutter can be mounted with which all kinds of obstacles can easily, reliably and quickly be removed from out sewage pipes.

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Claims (10)

A sewer cleaning robot for cutting a blocking object inside a sewer pipe, comprising: - a transport unit with a longitudinal axis and with controllable first operating means for displacing the transport unit in its longitudinal direction through a sewer pipe; 5. a rotary head provided at a front end of the transport unit, wherein the rotary head has a rotation axis that is parallel to the longitudinal axis and with controllable second operating means for rotating the rotary head around its rotation axis; - a movement mechanism connected to the rotary head, the movement mechanism having an outer end and having controllable third operating means for moving the outer end of the movement mechanism between radially inner and outer positions relative to the longitudinal axis; and - a cutter provided at the outer ends of the movement mechanism, characterized in that the cutter comprises a water jet cutter at the outer end of the movement mechanism, wherein a water supply is provided which is connected to the water jet cutter, and wherein controllable fourth operating means are provided for supplying pressurized water to the water jet cutter during a cutting operation such that a cutting jet of water is sprayed from a nozzle of the water jet cutter for cutting the blocking object. 2. Sewer robot according to claim 1, wherein a further rotary head is provided at the outer end of the movement mechanism, the further rotary head having a rotation axis perpendicular to the longitudinal axis, the nozzle of the water jet cutter being mounted on the further rotary head and wherein controllable fifth operating means are provided for the rotation of the further rotary head with the nozzle about its axis of rotation. The sewer robot of claim 2, wherein the nozzle of the water jet cutter is provided at an outer end of a pipe segment that projects outward from the further swivel head and has a length of 10-200 mm. 4. Sewer robot according to claim 3, wherein an extension pipe segment is provided with a length of 10-200 mm for replacing or extending the pipe segment carrying the nozzle of the water jet cutter. -10- 5. Sewer robot according to one of the preceding claims, wherein the movement mechanism comprises a movement arm which is connected to the swivel by means of a hinge connection, wherein the controllable third operating means are adapted to rotate the arm around its hinge connection between forward hinged and laterally projecting hinge positions with respect to the transport unit. The sewer robot of claim 5, wherein the moving arm has a length of at least 200 mm. Sewer robot according to claim 5 or 6, wherein the water supply comprises a pipe that extends through the swivel head and hinge connection. 8. Sewer robot according to one of the preceding claims, wherein the water supply comprises a water pressure hose that can extend from a pump unit above the ground to the robot. 9. Sewer robot as claimed in any of the foregoing claims, wherein a pump unit is provided that forms part of the water supply which is adapted to deliver water under a pressure of at least 200 bar to the nozzle. 10. Method for removing objects from a sewer pipe, comprising the steps of: - moving a sewer robot according to any of the preceding claims, within a sewer pipe to a position close to a blocking object therein; - turning the rotary head and / or moving the movement mechanism such that the nozzle of the water jet cutter comes to be at a distance of between 10-200 mm from the blocking object; and cutting the blocking object by supplying pressurized water to the water jet cutter such that a cutting jet of water is sprayed from the nozzle of the water jet cutter in the direction of the blocking object.