Vehicular device designed to operate in enclosed canals

A vehicular device designed to operate in enclosed canals includes a swivel head (25) which is connected by means of a rotatable and/or vertically adjustable boom (manipulator arm) (2) to the front end of a main chassis (3). The main chassis is fitted with rotatable supporting arms (6, 7; 6',7') to which are attached, both above and below and equidistant to the midline of the main chassis, pairs of wheels (8, 8'; 9, 9'; 28, 28', 29, 29'). The supporting arm or arms are maintained by means of a power source (16, 16') in a position of maximal spread in relation to the main chassis.

BACKGROUND OF THE INVENTION The present invention relates to a vehicular 
device designed to 
operate in enclosed canals. The device includes a main chassis and a swivel 
head attached by means of a rotatable arm and/or a vertically adjustable 
boom (manipulator arm) to the face of this main chassis. The device is 
equipped with wheels both above and below the main chassis. 
Preferably, the device is fitted with a head that is suitable for sand 
blasting the inner surfaces of closed canals. The head can, however, be 
fitted with an optical appliance, a gamma-ray radiator, a paint spray gun, 
an air-cleaner nozzle or with similar equipment, where it is important 
that, during the forward movement of the vehicle, the head maintains a 
prescribed distance from the inner surfaces of the canal being traversed. 
The European Application No. A-99 819 discloses a self-propelled vehicular 
device which is intended for operation in enclosed canals that cannot be 
approached by human beings (in this instance, the canals of atomic reactor 
facilities). The device has a central chassis to which are attached two 
rollers below and two others above the chassis. The front part of the 
chassis is bent forward over the lower rollers and thus achieves a 
detecting position, so that a detector mounted thereon can be moved along 
the floor of the canal. BY adjusting the angle of the bent chassis and by 
means of a slight twisting, a certain maneuverability of the detector is 
possible. The vehicle is maintained in this position by means of two upper 
rollers, one of which lies b.RTM.hind the other along the axis of motion. 
These upper rollers, which move along the ceiling of the canal, are 
mounted on two spring-loaded arms interlocked with each other. 
The disadvantage of this prior known vehicle is that the central chassis 
can achieve a particular average distance from the floor of the canal 
which is determined by the lower rollers. It is true that the upper 
rollers make possible a degree of control by pressure on the detector. 
However, allowances for the diameter of the canal cannot generally be made 
and an adjustment of the main chassis in relation to the center of the 
canal is not intended or possible. 
In order to create a vehicular device for operating in, inspecting, 
cleaning or sand blasting narrow canal inner surfaces, flat surfaces, 
ducts or other enclosed cavities which are difficult to pass or to reach, 
the device must be so designed that the main chassis can be adjusted to 
the exact midpoint between the upper and lower canal wall. By this is 
meant for example, canal tubes, aircraft air-intakes, gaseous smoke ducts 
and such objects whose tubes and gullies display a differing diameter 
along their length. 
Up until now, such canals were cleaned by persons who had to crawl into the 
canals. Such persons had to be completely enveloped in special suits and 
supplied from without with air to breathe. This activity was strenuous and 
posed extraordinary threat to health which could not be reasonably 
expected of any person over a long Period of time. 
SUMMARY OF THE INVENTION 
The principal objective of the present invention is to replace the manual 
sand blasting and similar activities previously carried out by persons by 
means of a vehicular device that fulfills all the requirements for an 
even, gentle and effective treatment and cleaning of such surfaces. One 
especially important objective is that the swivel head, in particular, a 
sand blasting head, be positioned and moved at a precisely predetermined 
and exactly maintained distance from the surface to be sand blasted, in 
order to avoid damage in the form of so-called head crashes. Particularly 
in the case of aircraft air-intakes, the interior of the canal is formed 
of extremely thin casing surfaces of only about 0.8 millimeter in 
thickness. 
These objectives, as well as other objectives which will become apparent 
from the discussion that follows are achieved, according to the present 
invention, by means of a vehicular device of the aforementioned type which 
is characterized by having at least two supporting arms attached so as to 
be able to move in relation to the main chassis. A pair of wheels are 
attached to each of these, both above and below the main chassis at an 
equal distance from its midline. 
This arrangement of a main chassis between four pairs of wheels insures 
that the midline of the main chassis is always at exactly the same height 
between the top and the bottom of the canal. Accordingly, a sand blasting 
head attached at the height of the main chassis maintains in every 
direction the same distance from the surface of canal to be cleaned. 
Preferably, the supporting arms with the wheels are so suspended that they 
turn in counter-rotation relative to one another and in relation to the 
main chassis. 
The vehicle is preferably so designed that the main chassis supports at 
least two supporting arms, each of which has four wheels and that one of 
the supporting arms lies immediately alongside the attachment of the sand 
blasting head. 
Furthermore, in a preferred embodiment of the invention an exact adjustment 
of a supporting arm is achieved by means of a power source, the supporting 
arm being maintained under tension, in relation to the main chassis, at 
maximal spread. The supporting arm's power source may comprise a torsion 
spring, a cylindrical spring, any other spring arrangement or even a 
hydraulic power source. 
Instead of wheels, skids or blocks can be employed, whereby the vehicle can 
be moved passively as well as actively by means of wheels. 
In order to keep the work field and the path of the vehicle free of 
deposited material that is utilized in sand blasting a sweeping device, 
Preferably a sweeper nozzle or Pair of nozzles, are attached to the front 
and the back of the vehicle. 
For a full understanding of the present invention, reference should now be 
made to the following detailed description of the preferred embodiment of 
the invention, and to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The vehicular device represented in FIGS. 1 to 4 comprises basically a 
vehicle 1 with a manipulator arm 2. The length and other dimensions of the 
vehicle are derived from the dimensions of the canals to be traversed. If 
the device is utilized, for example, for cleaning aircraft engine 
air-intakes, the diameter of which changes along its length, the clearance 
of the rotatable bearing (see below) in the direction of movement is about 
75 cm. All other dimensions can accordingly be derived from the 
illustrated embodiment. 
The vehicle 1 consists of a main chassis 3 that, seen from above has the 
shape of a closed frame. At both outer ends of the main chassis 3 pointing 
in both directions of motion are attached on both sides rotatable bearings 
4 4' and 5 5'. Each of the rotatable bearings 4, 4' and 5, 5' bears at its 
exact midpoint a supporting arm 6, 6' and 7, 7'. The four supporting arms 
6, 6' and 7, 7' bear, in their turn, at each of their ends a wheel 8, 8', 
9, 9', 28, 28' and 29, 29', each of which is equipped with a tire of an 
elastic rubber material. The distance between the wheels attached to a 
single supporting arms, for example 8 to 8', measured from the opposite 
crown to crown, is generally greater than the greatest inside diameter of 
the canal to be cleaned. 
The lower ends of the supporting arms 6 and 6', 7 and 7' are connected by 
means of crossbeams 18 and 19. Furthermore, the axles 20 belonging to the 
wheels 8, 28 - 8', 28' - 9, 29 - 9', 29' lie parallel to the crossbeams 8 
at right angles to the main chassis 3 and provide for reinforcement of the 
wheel-bearing structure. 
Below the main chassis 3 are two terminal boxes 11, 11', which are held in 
place by means of two curved stays 12, 12'. Attached to these two stays 
12, 12' are further two threaded blocks 13, 13' and 14, 14' which project 
downwards. Through the opening of each of the threaded blocks 13, 13' and 
14, 14', respectively, passes a threaded rod 15 which is connected, at its 
other end, to a cylindrical tension spring 16, 16'. The other end of the 
tension spring is attached to one of the crossbeams 18 or 19, 
respectively, whereby each of the two supporting arms belonging to it can 
be pulled in clockwise or counter-clockwise directions, respectively, 
until it is arrested by a detent (not represented), as is shown in FIG. 2. 
A corresponding spring 16' is attached to the rear end of the vehicle and 
pulls the corresponding supporting arm, respectively 6 or 6', in a 
clockwise direction. On the other side of the vehicle, corresponding 
springs work on the supporting arm 6' or 7, as can be seen in a view of 
the vehicle from above. Thus, the unloaded supporting arms stand at right 
angles to the horizontal main chassis. 
In narrow canals limited by a crown and floor, the supporting arms 6, 6' 
and 7, 7' are turned in opposite directions when the wheels on their ends, 
such as 8, 8', come into contact above and below with the inner surface of 
the canal. Moreover, the main chassis 3 lies exactly in the middle between 
the upper and the lower wheels so that the distance of the midline of the 
main chassis to the bottom or the crown of a canal to be traversed remains 
constant. 
The main chassis 3 is traversed in the middle by a central tube 22, which 
is interrupted at approximately its middle by a branch valve. To keep the 
FIGS. 2 and 3 simple, this branch valve has not been represented. 
Furthermore, at the end of the vehicle 1, provision is made for a 
connection of the central tube 22 to a flexible feeder tube (not shown). 
The central tube 22 is fed from outside the vehicle with streams of 
compressed air and a granular blasting material, which are supplied to a 
blasting device 25 at the end of the manipulator arm 2. 
The branch valve 23 is fitted with two steerable branch tubes 27, which 
lead to two cleaner nozzles 30, 30'; similar cleaner nozzles are also 
attached to the rear of the vehicle (not visible). The cleaner nozzles 20 
serve to clear the work field of left-over blasting material. After 
completing a predetermined cleaning phase, it is possible to move the 
blasting material to the end of the canal with the aid of the nozzles and 
to remove it by known methods. The branch valve is steered by means of a 
central unit. If needed, compressed air without sand blasting material can 
be fed to the vehicular device and blown through nozzles 30, 30', by means 
of this central unit which lies outside the vehicle. 
The propulsion of the vehicle 1 is effected via the wheels 9' and 29', 
which are driven by an electric motor 31 that moves these wheels backwards 
or forewards at varying speeds, according to the commands. As can be seen 
in FIG. 4, the electric motor 31 lies on a crossbeam 70 and is supported 
from below. The motor can be moved to and fro along this crossbeam in the 
directions of the arrows. Torque transmission is effected my means of a 
transmission 71 that contains a shaft 32. Depending on the angle, the 
electric motor of the supporting arm 6, 6', which drives the wheels, 
shifts its Position on the crossbeam 70 and follows in this manner the 
movement of the supporting arms and the wheels. 
Furthermore, a cable supplying energy and steering signals to the vehicle 
can be attached to the rear end of the vehicle by means of a plug and 
socket connection. A steering unit 33 is attached to the main chassis, 
from which emerge cables and other connections to the relevant part of the 
device. These functions will be described in detail below. The requisite 
steering leads are well known in the art so that these need not be 
described in detail. 
The Manipulator Arm 
A swivel head 40 for the manipulator arm 2 is attached to the vehicle, 
namely on the front face 30 of the chassis 3. The swivel head 40 is 
insulated from a base plate 42 and can be turned about its axis. A 
flexible tube 43 Pierces the base plate and the swivel head, leading to 
the blasting nozzle. The swivel head 40 is connected via a drive chain to 
the output shaft 45' of an electric motor 45, as is shown schematically in 
FIG. 3. In one variant (cf. FIG. ]) the electric motor 45 lies within the 
main chassis at right angles to the direction of motion and drives the 
swivel head 40 via a transmission (not shown here). The direction of 
rotation of the electric motor can be controlled. 
A frontal block 47 is attached to the swivel head. To this block are 
attached two pairs of parallel sliding bars 48, 48' and 49, 49'. The 
parallel sliding bars 48, 48' and 49, 49' end at a terminal block 50. The 
upwards and downwards movement of the terminal block 50 with regard to the 
frontal block 47 takes place via an electrically-driven, threaded-rod 
drive 51 with its threaded rod 5Z, which is attached externally at the 
support points 46 and 46' to the configuration of the parallel sliding 
bars. By the inwards and outwards movement of the threaded rod 52, the 
terminal block 50 is moved exactly in the vertical plane, maintaining at 
the same time its alignment with the main chassis 3, as can be seen in the 
two maneuver positions represented in FIG. 2. An electric motor 53 is 
flange-mounted to the underside of the terminal block 50. The motor's 
output drive shaft 53' is connected to a casing 54 which, in its turn, is 
linked via a bearing to a sand blasting head 25 comprising a nozzle 55 and 
a cross-over tube 55'. Two proximity detectors 58, 59, which are arranged 
at right angles to the direction of motion, are installed pointing 
downwards in the lower casing wall which lies horizontally 56. Two rubber 
mounts 60 are fitted in the neighborhood of the proximity detectors 58, 59 
as a protection against impact. The proximity detectors 58, 59 emit a 
signal as soon as the front end of the manipulator arm approaches closer 
to the wall than a certain preset minimal distance. In such a case, the 
sand blasting head can be tilted or removed. 
Description of Operation 
With the supporting arms set in the prescribed Position, the device is put 
into an opening at the front of a canal to be cleaned. At first, the 
manipulator arm is fixed in alignment with the main chassis. The device is 
moved forward to the beginning of the surface to be cleaned. The end of 
the surface to be cleaned is prolonged by means of an extension tube so 
that the vehicle can be driven so far along the canal that the sand 
blasting head 25 can sweep over the entire inner surface of the canal. 
It will be appreciated that the vehicle 1 can be driven backwards and 
forwards within a canal. The manipulator arm 2, which is attached to the 
front end of the vehicle, can carry out many movements as follows: 
Axis 1 
By means of the electric motor 45, the front block 47 with its attached 
parallel sliding bars 48, 48' and 49, 49' can be turned in both directions 
of rotation through 360 degrees. 
Axis 2 
With the aid of the electric linear drive via the threaded rod drive 51 
with the threaded rod 52, the terminal block 50 can be moved up and down 
without altering its exact vertical position. In this manner the clearance 
distances between the blasting nozzle 25 and the surface to be cleaned can 
be adjusted. 
Axis 3 
A rotatable module comprising the electric motor 53 and the casing 54 
continuously adapts itself automatically and in fine adjustment to the 
contours of the surface to be cleaned. The blasting nozzle is thus always 
oriented at an angle of 45 degrees, or some other predetermined angle, 
with respect to the surface. 
Axis 4 
The sand blasting head 25 with its nozzle 55 is driven by a pivot drive 57, 
that moves the nozzle in regular oscillating motions. In this manner, a 
spray width of, for example, 300 mm can be achieved. The spray width 
itself is limited by the requirement for evenness and can be preset by 
means of the adjustable oscillation angle. 
The movements about the axes 2 and 3 of the aforementioned motion systems 
function automatically; they are controlled by self-propelled steering 
equipment. This is the purpose of the proximity detectors 58, 59 attached 
to casing 54. 
After switching on, the device lowers the manipulator arm 2 by means of the 
movement of the threated rod drive slowly downwards until the minimal 
clearance of a proximity detector from the surface has been exceeded. As 
soon as this proximity detector (58 or 59) emits a signal, the threaded 
rod drive and the rotatable module - that is, the electric motor 
53--begins to rotate the casing with the proximity detectors. The rotation 
is always such that the neighboring proximity detector is moved towards 
the surface. To each of the proximity detectors is thus allocated a 
particular direction of rotation of the electric motor 53. When the second 
proximity detector responds, the manipulator arm is withdrawn until one of 
the proximity detectors ceases to emit a signal. Subsequently, a 
rotational movement follows in the direction in which the other proximity 
detector again responds. Should both detectors respond simultaneously, the 
manipulator arm 2 moves upwards and increases the distance between the 
nozzle 25 and the surface again. By means of this regulation via two 
proximity detectors 58 and 59, it is possible for the manipulator arm to 
follow the surface exactly and to allow a very precise sand blasting. 
By means of the constant undulating movement of the nozzle in the bearing 
54, a strip about 300 mm wide is carefully cleaned. 
Having driven along and cleaned this strip, the vehicle eventually reaches 
the end of the canal. BY regulating the rotatable section by means of the 
electric motor 45, the manipulator arm is rotated. The vehicle travels 
again to the beginning of the canal strip to be cleaned and senses 
independently the vault of the canal. At the same time, the oscillation 
width can, according to such requirements as paint thickness or fragility, 
be adjusted from the outset to differing rotational angles. During the 
following passage, the rotational angle is so altered that another strip 
is sand blasted. 
Various granulates or other materials known in the art can be utilized in 
the sand blasting. 
It will be apparent that with this tool it is possible to clean a canal 
surface without causing damage to the most difficult vaultings. Attention 
is also drawn to the fact that parts of the device projecting outwards 
that could possibly come into contact with the inner walls of a canal are 
preferably covered with a foam-upholstery material. 
Instead of a sand blasting head, optical equipment, a gamma radiation 
element, a paint sprayer, an air-cleaning nozzle or similar such tools can 
be employed, in all instances in which it is necessary that these units 
maintain in operation a constant clearance from a particular surface. 
There has thus been shown and described a novel vehicular device designed 
to operate in enclosed canals which fulfills all the objects and 
advantages sough therefor. Many changes, modifications, variations and 
other uses and applications of the subject invention will, however, become 
apparent to those skilled in the art after considering this specification 
and the accompanying drawings which disclose the preferred embodiment 
thereof. All such changes, modifications, variations and other uses and 
applications which do not depart from the spirit and scope of the 
invention are deemed to be covered by the invention which is limited only 
by the claims which follow.