The invention relates to a method and an apparatus for inspecting and checking the condition of smoke flues or the like chimneys. The invention especially relates to a method for the inspection of an essentially vertical smoke or air flue utilizing a video or the like camera means which, depending from a supporting means, is lowered down into said flue for relaying an image of the inside space of said flue to a control unit located outside said flue, as well as an appa¬ ratus for the inspection of an essentially vertical smoke, air or the like flue, said apparatus comprising a video or the like camera means being arranged into an essentially sealed housing, said camera means transmitting a picture of the flue portion located ahead thereof to a control and monitoring unit located e. g. at the top of said flue or at another suitable location.

Traditionally, the aim is to build the flue of a smoke chimney so that it is smooth and sealed from the beginning. A chimney inspection procedure thereafter notes that "the flue is built", and the chimney is then accepted for use. If there are special reasons to suspect that a flue will leak a special smoke test will be performed. Smoke having a slight over¬ pressure is then brought into the flue, after which suspected portions are checked and any asecape smoke is observed.

During use the only regular inspection is performed in con¬ nection with chimney sweeping, where the chimney sweeper, depending on his professional skill and experience and using normal chimney sweeping means, forms a subjective image of the chimney' s condition. Thus, the inspection most often is re¬ stricted to a visual inspection from the ends of the flue and through inspection hatches or shutters, using auxiliary means like flashlights and mirrors or the like. If some portion is really suspicious the flue is opened up at that location,

CORRECTED

which is a task which is both laborious and destroys the entity of the flue. Until now there has actually been no reliable method for inspecting the inner surface of a flue or the work of a mason or chimney sweeper. Correspondingly, it has been difficult and sometimes impossible to determine the air flows and temperature conditions in a flue.

Prior art, however, discloses many kinds of arrangements for inspecting pipings and the like, utilizing video devices. Said arrangements usually comprise a video camera device which usually is arranged in a sealed housing, as well as supplying, transferring and controlling means for said device. Said means usually comprise fairly complicated devices and, in fact, such devices are generally used for the inspection of horizontal pipings and for the accomplishment of service operations. As an example of such devices e. g. EP-patent application No. 108 587 and Finnish patent application No. 911384 may be mentioned. Further, from FI-patent application No. 871640, O-publication No. 86/04475 and O-publication No. 92/08321 different arrangements for processing the pictures transferred by a video camera are known.

German publication OS-29 12 606 discloses an apparatus in¬ tended mainly for inspecting and repairing of waste chutes, said apparatus comprising a video camera suspended from above on a cord, as well as repairing means arranged in the same apparatus. This device is heavy and clumsy and it cannot be brought, in an appropriate manner, from one flue to another on a rooftop. Further, it does not provide any possibility to follow, from the outside, the advance of the apparatus and to compare the pictures transferred by the apparatus to the situation to be seen outside the chimney. For a satisfactory function this known device needs a very straight chute and it cannot follow a flue which sometimes also extends in a slanting direction in such a manner that the exact direction of the device could be guaranteed.

WO-publication No. 91/18236, on the other hand, discloses an inspection arrangement for tubes, where a small video camera can be pushed in a piping in front of a flexible wire, said device having elastic sledge or brush means for centering said device in said tube This device is also incapable of trans¬ ferring information regarding its position to the outside of the flue, and its direction in the tube cannot be exactly defined Until now, all known devices have in common that the device is heavy and clumsy and it cannot m a safe and easy manner be transported on a roof from one chimney to another other.

The ob ect of the invention is to provide such an arrangement wherein a light video device adapted in a housing can be brought, in a simple manner, into conventional essentially vertical flues, and where the location and direction of the device can be exactly controlled and the location information can be transferred to the outside of the flue.

The characteristics of the invention are evident from the appended claims. Thus, the inventive method is characterized in centering said camera means in the flue and bringing it to advance therein essentially without rotation, while simul¬ taneously transferring, to the control unit, pictorial in¬ formation from the inside of said flue at the location of said camera means; in defining the vertical location of said camera device in said flue; and in combining in said control unit the locational information with the pictorial information in order to determine the nature and position of possible follow-up actions. For the inventive apparatus it is characteristic that said camera means with its housing is suspended on a longi¬ tudinally extending support means, and that the apparatus further comprises devices for guiding said housing in directions transverse to the longitudinal direction of said flue and for keeping said housing essentially without rotation in said flue, means for determining the location of said camera means further being attached to said housing.

The invention will now be described m more detail with refe¬ rence to the appended drawing, wherein:

Figure 1 schematically discloses the general arrangement ac¬ cording to one embodiment of the invention, and

Figure 2 in more detail discloses a video camera arrangement according to one embodiment of the invention, seen from below through a flue.

In Figure 1 there is generally disclosed a housing 1 com¬ prising a video or the like camera 2 which is capable, suitably via a cord 3, of transferring to a control means 5 located at the outside of said flue 4 a picture from the in¬ side of said flue. For this purpose said housing 1 comprises a window 6, through which said camera 2 will take a picture of the flue portion ahead. There is also suitably an illumination means 7 for illuminating the flue portion to be depicted. In a favorable embodiment the whole housing is manufactured from transparent plastics, in which case the function of the camera is easy to check. Since an apparatus to be brought into a flue will not be exposed e. g. to a fluid pressure or the like the protective housing 1 may be of a fairly light construction. Favorably, a small size video camera having a wide angle objective and intended e. g. for a control device will work as said camera. The weight of the whole assembly can be kept very low, typically at 0.7 to 1.0 kilograms.

Said housing 1 is suspended on a longish support means, which favorably is constituted by a cord 3, which, as such, might comprise several separate conductors for the device' s dif¬ ferent functions. In order to keep said housing 1 in place in said flue 4 said housing comprises centering means extending outwards therefrom, said means favorably comprising whisker means 8. Said whisker means 8 are suitably interchangeable whiskers made of suitable a flexible material like plastics,

and according to a preferred embodiment of the invention they can be moved horizontally, i. e. in a direction transverse to the general extension of said flue 4, in accordance with external controls.

Figure 2 discloses an enlargement of a preferred embodiment of the invention, seen from below said housing in ist travel direction, said whisker means extending, in the embodiment disclosed, in four different directions. In the embodiment disclosed said whisker means 8 chiefly rest in the corners of said flue, which facilitates a steady advance and good positioning. Thus, the main function of said whisker means 8 is to center said housing 1 in said flue 4. Said whisker means 8 further prevent said housing from rotating in said flue 4. Thus, the picture transferred by said camera 2 to the outside of said flue 4, as well as all details shown in said picture, can always be exactly determined with respect to the direction of the flue walls.

In a tubing imaging procedure according to the prior art the transversal direction of the picture transferred by the imaging device, with respect to the imaging axis, is not of any great importance, since a tube usually has a rather concise structure. If, in a tubing imaging procedure, there occurs observations which demand some actions to be taken the whole tubing is usually dug up, and thus the specific location usually can be quite clearly accessed from the outside. Another possibility is to conduct e. g. a repairing action inside the tube under the camera' s supervision.

In a chimney flue imaging procedure it is, as distinguished from tube imaging, especially important that the depicted area can be exactly determined in all extensional directions. This demand is due to the general structure of chimney flues, where there usually are several parallel flues, and adjacent flues usually have common walls. In this case the accomplishment of a service or repair action demands considerably exacter

locational information, in comparison to tube imaging. In tube imaging the direction of the camera is usually at least gene¬ rally determined to the horizontal plane, and thus one does not need to care for the orientation of the camera, whereas in flue imaging a freely suspended camera might rotate around its central axis. In such a case the directional information given by the picture is easily be lost, resulting in the actions directed to the flue becoming more difficult.

Contrary to the prior art the direction of the camera can always be determined in accordance with the present invention In this case the orientation remains essentially the same, if it is not deliberately changed in accordance with a favorable embodiment of the invention. This may be the case when a cnimney flue is divided, e. g. where several flues 4 inter¬ connect. In such a situation the inventive device can favorably be guided to advance in a selected flue.

According to a preferred embodiment of the invention this guidance is arranged in such a manner that at least some of said whisker means 8 can be controlled, with respect to their direction and/or their transversal dimension in relation to said housing 1, for instance using a servo means 9, as is indicated with an arrow in Figure 2. In a favorable embodiment a steerable whisker means 8 thus comprises a servo motor which is capable of controlling the offset of said whisker by moving it in its longitudinal direction. Then said whisker 8 could favorably extend through the apparatus in such a manner that one control operation provides a situation wherein whiskers 8 extend essentially only on one of the opposite sides of the camera housing, whereby the camera will be guided in the opposite direction.

According to another embodiment of the invention the control of the apparatus is arranged with one or several special guiding means extending suitably m the longitudinal direction of said housing, said guiding means being pivotable in the

lateral direction so that said guiding means at the location of a flue junction can be brought to extend into a selected flue. Said housing will follow said guiding means which are preferably electrically operated, whereby the flue to be examined can easily be chosen. In one embodiment said housing comprises further means for turning the entire camera arrange¬ ment so that pictures can be taken looking e. g. into a flue extending horizontally. Further, the apparatus suitably also comprises turning means by which a camera positioned hori¬ zontally in the above described manner can still be rotated in the horizontal direction for taking exact images of the flue wall. In one embodiment this function is effected by a prism or mirror arrangement which can be operated into position in front of said objective window 6.

In a simple embodiment said suspension means, i. e. said cord 3 suitably comprises indications of length, in which case the running depth of said camera 2 can be directly read on said cord. In the embodiment disclosed in Figure 1 said cord further runs via a special reading device 10, which favorably transfers information regarding the length of the passed cord portion to said control unit 5.

In order to determine the position of the apparatus also in a different way the apparatus further favorably comprises a mechanical hammer device 11 and/or a microphone 12 acting as a sound indicator. Said hammer device 11 or knocker favorably comprises a magnetic pecker device located inside said pro¬ tective housing 1, said pecker being controllable for directing knocks against the wall of said flue 4. With these devices a sound based connection can be established between said camera 2 in the flue and a person positioned outside said flue 4. In this case said person favorably has a radio tele¬ phone 13 connection to a radio telephone 14 operated by the person who operates a control device 5a on the roof at the upper portion of the flue 4. At the control unit 5 the picture taken by said camera is suitably shown on a monitor 5b. The

information data given by other extra devices arranged at the device is favorably disclosed on said control device 5a and/or said monitor 5b.

Favorably the protective housing for said camera means is built to be tapered at its ends, so that said housing and the camera therein can run easily m said flue and pass any uneven portions 4a. The tapered shape also facilitates the guiding of the apparatus m the flue. The afore described whisker means 8 also act in such a manner that they keep said housing 1 away from the walls of said flue 4 and thus they prevent the engage¬ ment of said housing to uneven portions 4a of said wall, to lumps of seaming plaster or the like. Said whiskers are favorably relatively thin, about a few millimeters, in order to enable also the whiskers to pass said obstructions. Figure 1 discloses how a whisker means 8 evades an uneven portion 4a by a suitably bending.

Favorably said control unit 5 further comprises means known per se for storing, the picture supplied by said camera 2, e. g on a video player 15, a microphone 16 and/or a titling device 17 connected to said player, or the like means for storing information m connection with the pictorial information.

One area of use of the invention concerns determining the temperature and/or flow conditions which prevail m the flue 4. For this purpose a favorable embodiment of the invention comprises, besides the actual picturing means, also sensor means 18 for gauging the temperature outside said protective housing 1 of said camera 2. By monitoring the temperature of the air in said flue 4 one can find out the reasons for air flow disturbances m a natural ventilation flue. Especially favorably the apparatus also comprises means for producing smoke into the view field of said camera 2. Such means com¬ prise a smoke generator 19 arranged either in said housing 1 or at said control unit 5, from which generator a thin j et of smoke can be guided, suitably through a nozzle 19a, in front

of the camera 2 The smoke w ll follow the air flow prevailing in the flue and thus the movements of the a r in the flue can be illustrated by taking pictures of the smoke In the same manner one can proceed in order to check the consistency of the intermediate walls between separate flues In this case a modification of an arrangement according to the invention can also be used, wherein a smoke generator is set to function in a flue adjacent to the one which is to be inspected, favorably on a level defined in accordance with the invention, in which case the flue to be inspected is pressurized and any possible smoke breaking into the adjacent flue is observed using a camera device according to the invention.

In one embodiment of the invention the apparatus is further supplemented with a sampling device for taking samples in order to discover e. g. the presence of asbestos or the quality of the soot. Said sampler (which is not especially disclosed m the Figures) favorably comprises a shaft working tele- scopically or being turnable, at the end of which there is a remote controlled sampler head Said sampler head suitably comprises a bucket shaped scraper means which can be closed when the sample material has been detached. The whole assembly is favorably so located that the function of said sampler means can be monitored via the picture transferred by said camera means 2.

The aforesaid components are favorably interconnected via a suitable cable work, which suitably at the same time forms the camera supporting means 3 by which said camera 2 is lowered into said flue. The distance between said camera and said control- and monitoring equipment can suitably be from 0 to 500 meters, where the control function favorably is effected using radio telephone communication between, on one hand, a person located at the end of the flue or even down on the yard of the building and, on the other hand, a person positioned in the vicinity of the chimney flue on the level where the picture is taken. If said radio telephone communication in

some special cases should weaken the picture quality due to disturbances emanating from said radio communication it is possible in this respect also to rely on cable based communi¬ cations in vicinity of the camera, the radio transmitter being located at a greater distance.

On order to facilitate the advance of the apparatus in a winding flue the apparatus further comprises, according to one embodiment, separate pulling means. In the most simple case said pulling means comprise a ball which is suspended on a cord under the device. A ball with a proper weight will descend m the flue m front of the camera assembly and will pull the assembly therewith also in case the flue extends m a sloping direction. Another transporting and guiding means which can be utilized in a device according to the invention comprises a suitably telescopic bar means, at the end of which there are means for holding said camera means and favorably for turning said means from a horizontal positions to a verti¬ cal position. At said bar means the camera assembly can be transported also in a sideways direction e. g. in an eave gutter from which it can be lowered down to inspect discnarge chutes or the like. Further, there is preferably also a runner wheel arranged at the end of said telescopic means, through which wheel said supporting means 3 runs.

Above there has been discussed some characteristic features and ranges of use for the inventive arrangement. For a pro¬ fessional it is clear that the invention can be altered in many other ways within the scope of the appended claims.