WO2020050711A1

WO2020050711A1 - Inspection device for use in a potentially explosive atmosphere

Info

Publication number: WO2020050711A1
Application number: PCT/NL2019/050536
Authority: WO
Inventors: Roelof SCHREURS
Original assignee: Exrobotics B.V.
Priority date: 2018-09-07
Filing date: 2019-08-16
Publication date: 2020-03-12
Also published as: NL2021581B1

Abstract

The invention relates to an inspection device for use in a potentially explosive atmosphere, comprising at least one thermally conductive and substantially pressure-resistant and preferably substantially closed housing with an optical sensor provided therein, wherein device is configured to obtain a tilting and/or panning effect of the optical sensor without having to tilt and/or pan the optical sensor itself.

Description

Inspection device for use in a potentially explosive atmosphere

The invention relates to an inspection device for use in a potentially explosive atmosphere. The invention further relates to a mobile inspection robot for use in a potentially explosive atmosphere comprising at least one inspection device according to the invention.

Inspection devices for use in potentially explosive atmospheres can be particularly useful for monitoring and/or control of the local situation in hazardous areas. Such inspection devices may for example be configured for the detection of gases and/or particles. The detection and/or identification of for example flammable and/or explosive gases or particles can be of major importance for safety reasons. For this purpose can for example made use of an inspection device provided with a thermal imaging camera. It is, however, a challenge to provide an inspection device which fulfils the European ATEX regulations, or any equivalent thereof, for use in potentially explosive atmospheres. Such inspection device therefore requires an explosion-proof enclosure for the electrical components such that the device can be classified as intrinsically safe. This intrinsic safety is required in order to guarantee that failure of the electrical components cannot cause ignition.

It is a goal of the invention to provide an improved inspection device for use in a potentially explosive atmosphere.

The invention provides thereto an inspection device for use in a potentially explosive atmosphere, comprising at least one substantially closed explosion-proof housing, the housing being preferably thermally conductive and preferably substantially pressure-resistant, said housing comprising at least one substantially translucent window for the transmission of light, at least one optical sensor, preferably being a camera, accommodated within said housing, at least one reflective element for reflection of light accommodated within said housing, and at least one drive unit, in particular an electrical drive unit, accommodated within said housing, wherein the at least one reflective element and the window are positioned such that environmental light transmitted through the window into said housing will be reflected by the reflective element in the direction of said at least one optical sensor, such that the environmental light can be received by the optical sensor, and wherein the optical sensor is substantially stationary mounted in the housing, and wherein the (electrical) drive unit is configured to move, and in particular to rotate, at least one reflective element within said housing and with respect to the optical sensor such that the viewing angle(s) of the optical sensor can be adjusted.

A benefit of the inspection device according to the invention can be found in the use of an optical sensor in combination with a - with respect to said optical sensor - movable, and in particular rotatable reflective element. The at least one reflective element herewith forms part of an optical path between the at least one window and the at least one optical sensor. Due to the use of the movable, and in particular rotatable reflective element is it possible to adjust the one or more viewing angles of the optical sensor without having to move the optical sensor as such. The detection field of the of the optical sensor can be adjusted while the optical sensor remains substantially stationary. Also the optical path between the reflective element and the window can be adjusted with respect to the optical path between the reflective element and the optical sensor. It is in particular possible to obtain a tilting and/or panning effect of the optical sensor without having to tilt or pan the optical sensor. Tilting and/or panning of an optical sensor results in a widened field of view of the optical sensor in various directions, in particular in horizontal direction and/or in vertical direction. Due to the field of application, i.e. a potentially explosive atmosphere, it is desired that tilting and/or panning of the optical sensor in order to adjust the viewing angles is an electrically driven process. However, optical sensors used for inspection purposes can be relatively heavy. Additionally, the optical sensor is enclosed by the explosion-proof housing which also increases the total weight which needs to be moved, in particular tilted and/or panned. Tilting and/or panning of the optical sensor as such, and in particular the entire inspection device is therefore relatively energy consuming which consequently requires a relatively powerful drive unit, which would generate a considerable amount of thermal energy which is undesired and even dangerous in explosive environments. Due to the use of the movable, and in particular rotatable reflective element, it is possible to keep the optical sensor, and thus also the housing, in a substantially stable (stationary) position while a similar tilting and/or panning effect of the optical sensor can be simulated and therefore a similar widened field of view can be obtained. The drive unit can move, and in particular rotate, the at least one reflective element with respect to the optical sensor either directly or indirectly. The reflective element can be relatively light weight and the reflective element generally weighs only a fraction compared to the optical sensor. Therefore it is relatively energy efficient to move, and in particular rotate the reflective element, wherein a negligible amount of thermal energy is generated, which is beneficial in explosive environments. A more energy efficient way to obtain an adjusted viewing angle of the optical sensor is beneficial for multiple reasons. This for example enables the use of an (electrical) drive unit with a relatively small capacity. A drive unit with a relatively small capacity can generally benefit a relatively small volume, which may contribute to the inspection device having a relatively compact design. The relatively small capacity of the drive unit is furthermore beneficial for safety reasons, since this may reduce the risk of explosion or may at least cause a less impactful explosion. This is beneficial for the (intrinsic) safety of the device. The substantially stable position of the optical sensor and the housing is furthermore spatially seen beneficial as the physical space needed by the inspection device during inspection is relatively small. When the inspection device itself is tilted (vertically) or panned (horizontally) a space surrounding the device is required to enable movement of the device which is limiting for the possibilities of use, in particular in difficult accessible areas. This drawback can also be overcome by making use of the inspection device according to the invention. A further advantage of the substantially stable position of the inspection device can be found in that flexing of any cables entering the housing of the device can be minimized which can prevent impairment of the cables.

The inspection device is preferably an explosion-proof inspection device. Since the device is configured for use in a potentially explosive atmosphere the housing needs to be explosion-proof. With an explosion-proof housing a housing is meant which fulfils the European ATEX regulations, and/or any equivalent thereof, for use in potentially explosive atmospheres. This requirement can for example be met by the housing being preferably thermally conductive and preferably substantially pressure-resistant. The explosion-proof housing is generally substantially closed. Due to the enclosure of the electrical components, e.g. the optical sensor and the drive unit, by means of the explosion-proof (pressure-resistant), substantially closed housing, any explosion initiated within in the housing will not be able to continue outside the housing, as a result of which the inspection device according to the invention can be applied relatively safe in a potentially explosive atmosphere. Heat (thermal energy) generated within said housing, in particular by using the optical sensor and/or the drive unit, will commonly at least partially be dissipated to the surrounding atmosphere via the preferably thermally conductive housing. In addition, the explosion-proof housing results in the inspection device being intrinsically safe and therefore enables the use of standard (electrical) components in the housing. The housing comprises at least one substantially translucent window for the transmission of light in order to enable light from the environment to be received by the optical sensor. With translucent it is meant that the window is light-permeable. The light can be visible light and/or invisible light. Light is electromagnetic radiation within a certain range of the electromagnetic spectrum, with a typical wavelength of between 300 nm and 1 mm. Due to the strategic positioning of the window wherein light emitted and/or reflected from the

environment can pass through the window and will subsequently be reflected by the reflective element such that the light can be received by the optical sensor, the field of view of the optical sensor can at least partially be determined by the window. The window is generally positioned at a distance from the optical sensor. The window is generally positioned at a distance from the reflective element.

Although it is conceivable that the housing is one integral unit, it is usually preferred from a practical and economic point of view that the housing is a modular housing. In such an embodiment, the housing for example comprises a main body enclosing an accommodating space for the at least one optical sensor, the at least one reflective element, and the drive unit, wherein said main body is defined by at least one circumferential wall enclosing at least one wall opening, wherein each wall opening is substantially closed, preferably in a medium-tight manner, by at least one closing element of said housing. A closing element may - in typical situations - be considered as a lid. An advantage of the modular housing that this type of housing can be manufactured in a relatively cost-efficient manner. Moreover, by using one or more apertures (wall openings) in a wall of the main body,

(de)installation and maintenance of components accommodated within said housing can be facilitated. The main body is possibly substantially cylindrically shaped, and each outer end opening of the substantially cylindrically shaped main body can be substantially closed by a closing element of the housing. The outer end opening can also be referred to as wall opening. In a possible embodiment of the inspection device comprises the housing a substantially main body wherein the optical sensor, the reflective element and the drive unit can be received and at least one, and preferably two closing elements connected to the main body for medium- tight sealing of the housing. The housing, and in particular the main body is generally substantially elongated. The housing can for example be substantially tubular as a tubular shape may provide an even pressure distribution, which is advantageous in order to conserve the desired intrinsic safety of the inspection device. However, the inspection device invention is not limited to a tubular shape, and may possibly have any other shape configuration. It is furthermore possible that a modular embodiment of the inspection device according to the invention comprises at least one sealing element. A sealing element can for example be used in order to improve the connection between two modular parts of the housings. It is however of importance that the sealing element does not negatively affect the explosion proof characteristics of the inspection device. The sealing element can for example be manufactured of a metal material. A non-limiting example thereof is a leaded bronze alloy.

It is conceivable that at least a part of at least one closing element is located within a volume enclosed by the main body. This may further improve the pressure resistance of the housing. It is in particular beneficial if at least a part of at least one closing element engages an inner wall surface of the circumferential wall of the main body of the housing, preferably such that a circumferential seam is formed between the inner wall of the main body and the closing element. The

circumferential seam can also be referred to as flame path. The circumferential seam, or flame path, allows gases caused by an internal explosion to exit the housing and to cool down during the passage, so that they are no longer able to trigger the outside atmosphere. This contributes to the intrinsic safety of the device. For this reason, the flame path must be sufficiently long and with an interstice enough narrow to guarantee the cooling of the flue gases. The width of the circumferential seam is for example at least 10 millimetres, preferably at least 13 millimetres.

An embodiment of the inspection device is also possible wherein the interior of the substantially closed explosion-proof housing is filled with gas at an overpressure. This means that the pressure inside the housing of the inspection device is higher than the ambient or environmental pressure. Non-limiting examples of gas which can be used to fill the interior of the housing are for example oxygen and/or nitrogen. By applying an (constant) overpressure in the substantially closed housing it can be prevented that (explosive) gas mixtures from the ambient atmosphere enter housing. This will contribute to the intrinsic safety of the inspection device. The housing is preferably manufactured with exact tolerances such that a single gas filling allows safe operation over the entire service life of the inspection device. It is beneficial for this embodiment if the housing is non- permeable for the gas used or at least has a low gas permeability.

A further possible embodiment of the inspection device according to invention is possible wherein the housing comprises a body part and a head part co-acting with said body part, wherein the head part is movable, in particular rotatable, with respect to the body part, wherein at least one optical sensor is received in the body part, and wherein the head part comprises at least one window and wherein at least one reflective element received in the head part, and wherein the drive unit is received in the body part and/or head part and wherein the drive unit is configured to move, and in particular to rotate, the head part with respect to the body part. The optical sensor is, in this embodiment, generally stationary mounted in the body part of the housing. The housing comprising a body part and a head part can be seen as a modular housing. The body part and the head part are configured for mutual co-action, such that mutual displacement can take place. Given that the reflective element is received in the head part of the housing, the reflective element can be either directly or indirectly be moved, and in particular be rotated, by the drive unit, with respect to the body part. It is beneficial that the housing comprises a body part and a head part, wherein the head part is movable, in particular rotatable, with respect to the body part since it is relatively easy to control the movement, and in particular the rotation of the head part with respect to the body part. This contributes to a more accurate (rotational) movement of the head part and subsequently to more controlled inspection possibilities. The movement, and in particular the rotation of the head part with respect to the body part is also relatively energy efficient wherefore an (electrical) drive unit with a relatively small capacity can be used. As outlined above, the use of a drive unit with a relatively small capacity is beneficial for multiple reasons. The head part is generally present at an outer end of the inspection device. It is possible that the reflective element is substantially stationary mounted in the head part of the housing such that moving, and in particular rotating of the head part causes the reflective element to move, and in particular to rotate with respect to the optical sensor and/or with respect to the body part of the housing. The reflective element can for example be (integrally) connected to head part. The reflective element will benefit a rather stable positioning the head part which contributes to a more solid construction of the device. This is beneficial for the durability of the inspection device. A further benefit of this embodiment is that a relatively small translucent window can be used. The window is generally provided in the head part of the housing, wherefore the window is automatically moved when the head part of the housing is moved, in particular rotated. The mutual positioning of the window and the reflective element will in this embodiment remain constant during (rotational) movement of the head part with respect to the body part. The field of view can be influenced by the dimensions of the window. However, when the reflective element is stationary mounted in the head part of the housing, the dimensions of the window can be chosen such that light emitted and/or reflected from the environment which passes through the window will reach the reflective element. The window can therefore be relatively small, which is cost-efficient.

The head part is preferably configured to rotate with respect to an axis of rotation which is in line with a longitudinal axis of the body part of the housing over at least 90 degrees, preferably at least 120 degrees and more preferably at least 180 degrees. With an axis of rotation of at least 90 degrees, preferably at least 120 degrees and more preferably at least 180 degrees is a relatively wide field of view of the optical sensor obtained. It is however, also possible that the head part can rotate up to 360 degrees with respect to the body part.

It is possible that the head part of the housing encloses, in particular circumvents, at least part of the body part of the housing. This configuration further simplifies moving, and in particular rotating of the head part with respect to the body part.

Also a more controlled movement, in particular rotation, can be initiated with this configuration. With this embodiment it is possible that the reflective element and the drive unit are enclosed by both the head part and part of the body part. A benefit of this embodiment is that bending of any electric cables present inside the device, for example an electric cable connected to the drive unit, can be prevented. It is further possible that an inner wall of the head part at least partially engages an outer wall of the body part. This will typically result in a telescopic co-action between the body part and the head part. Additionally, a circumferential seam can be formed between the inner wall of the head part and the outer wall of the body part. The

circumferential seam can also be referred to as (dynamic) flame path. As outlined above, the presence of flame paths may positively contribute to the intrinsic safety of the inspection device.

For an embodiment of the inspection device according to the invention comprising a head part a body part, it is possible that the drive unit is connected to both the body part and the head part of the housing. This may further improve the mutual co-action of the housing parts which may result in further controlled (rotational) movement of the head part with respect to the body part. It is beneficial if the length of the head part of the housing is smaller than the length of the body part of the housing. It is in general beneficial if the housing part is relatively small and/or lightweight, since this facilitates easy movement, in particular rotation, of the head part with respect to the body part. The head part is generally present at an outer end of the device. Preferably, the at least one drive is positioned substantially within the head part of the housing.

The optical sensor of the inspection device according to the invention is generally a camera. The camera comprising at least one optical sensor. The camera may in particular be a thermal imaging camera. This can for example be an infrared camera, a thermal infrared camera or a thermographic camera. The camera is in particular configured for gas and/or object detection. The camera can for example be used for thermal scanning. It may be beneficial in case the inspection device, in particular the camera, comprises at least one infrared light source, wherein the reflective element is configured for reflecting the light of the supporting infrared light source towards the window. To this end, the light of the supporting infrared light source will typically follow a similar or equivalent, though opposite, optical path as the path followed by the incoming environmental light from the environment which is reflected by the reflective element. The use of a (infrared) light source within the inspection device is commonly used to illuminate the direct environment

(surrounding the device), wherein reflections (towards the window) may subsequently be detected by the camera. It is possible that the camera is configured for real time monitoring.

An embodiment of the inspection device is possible, wherein the reflective element comprises at least one mirror reflective surface. The use of a mirror reflective surface may enable more controlled reflection of (infrared) light. The mirror reflective surface can for example comprise a substantially flat and/or smooth surface. This will provide a more predictable reflection, which is beneficial for controlled inspection of the environment. It is possible that the mirror reflective surface extends in a flat plane. This can further contribute to a predictable reflection. It is however, also possible that the mirror reflective surface is at least partially curved and/or parabolic. It is even possible that the shape of the reflective surface is adjustable, for example by exerting a mechanical and/or pneumatic pressure to the reflective element. It is possible that the mirror reflective surface is inclined with respect to a longitudinal axis of the housing, in particular of the body part of the housing. The mirror reflective surface is for example about 45 degrees inclined with respect to aforementioned longitudinal axis. The positioning of the mirror reflective surface should in particular be adapted to the desired field and/or angle of view of the optical sensor, for example the camera. The orientation of the mirror reflective surface is in a possible embodiment of the device adjustable. The mirror reflective surface preferably has at least two degrees of freedom wherein the mirror orientation can be adjusted. This enables that the mirror reflective surface can simulate both a tilting and a panning effect. It is possible that the drive unit is configured to adjust the orientation of the mirror reflective surface. The reflective element is for example configured to rotate with respect to an axis of rotation which is in line with a longitudinal axis of the optical sensor over at least 90 degrees, preferably at least 120 degrees and more preferably at least 180 degrees. It is beneficial if the mirror reflective surface is coated with a metallic coating, in particular a layer of a noble metal, in particular gold and/or silver. Gold, for example bare gold or protected gold, can be used for this purpose due to its high reflectance for near-infrared (NIR) and infrared wavelengths. This also applies to silver, where protected silver for example provides a high reflectance for light with a wavelength of about 500 - 800nm. It is however also possible that the mirror reflective surface is coated with aluminium, or that the mirror reflective surface is at least partially made of aluminium. A further embodiment is possible wherein the inspection device, and in particular the reflective element, comprises multiple mirror reflective surfaces. It is also conceivable that the inspection device comprises a plurality of reflective element, which may or may not be in the line of sight which each other. This makes it possible to realize at least one more complicated optical path for the light within the housing. The different reflective elements may have a fixed position with respect to each other. It is also imaginable that at least two reflective element are mutually displaceable with respect to each other. This latter can, for example, be achieved by mounting at least one reflective element to the head part of the housing, and by mounting at least one other reflective element to the body part of the housing.

In a possible embodiment of the inspection device is the translucent window releasably connected to the housing by means of several screws. This technical feature enables at least one static flame path can be provided at or near where the window and the housing mutually engage. Furthermore this enables relatively easy replacement of the translucent window in case the window needs to be removed for for example cleaning purposes. The substantially translucent window can for example be made of protective glass. Protective glass is in particular suitable for use in a potentially explosive atmosphere. The substantially translucent window can for example be made of sapphire glass. Sapphire glass benefits a high hardness and a good (scratch) resistance, which properties are favourable in explosive environments. Sapphire glass benefits in particular a high durability.

The drive unit of the inspection device according to the invention can for example be an electrical drive unit. The electrical drive unit more particularly be a

servomotor. A servomotor benefits a relatively easy motion control for both rotary and linear motion, and benefit relatively high maximum speeds and short acceleration times. A further important advantage of the servomotor is its compactness which is beneficial in order to reduce the total volume of the inspection device. This also applies to the weight of the servomotor. Preferably, the at least one drive unit, in particular the at least one electrical drive unit, more in particular the at least one servomotor, is powered by at least one battery making part of the inspection device and/or making part of a mobile inspection robot for use in a potentially explosive atmosphere comprising at least one inspection device according to the present invention. In this latter case, the battery may also be used to power the robot, and in particular to power/drive one or more transporting wheels of the inspection robot. The at least one battery is preferably (also) accommodated within the housing of the inspection device.

In a preferred embodiment of the housing is the housing thermally conductive. A thermally conductive housing may enable heat or thermal energy generated within the housing, in particular by using the optical sensor and/or the (electrical) drive unit, to be at least partially dissipated to the surrounding atmosphere via the thermally conductive housing. The housing will generally be at least partially, and preferably entirely manufactured of a metal, in particular aluminium. The advantage of metal, and in particular aluminium is that aluminium has good thermal conducting properties, is relatively inexpensive and is sufficiently machinable. Aluminium can therefore be used as material for explosion-proof housings. A further benefit is that aluminium is relatively inexpensive.

The inspection device, and in particular the housing thereof may in a possible embodiment be configured to be connected to at least one electric cable. A benefit of this embodiment is that bending of such electric cable can be minimized due to the mainly stationary position of the housing during use.

Preferably, the inspection device comprises at least one control unit to

electronically control the inspection device. The control unit is preferably configured to communicate wirelessly with a distant terminal station. Preferably, the control unit is configured to be controlled remotely, more preferably by means of said distant terminal station or by any other remote control.

The invention furthermore relates to a mobile inspection robot for use in a potentially explosive atmosphere comprising at least one inspection device according to the present invention. The mobile inspection robot can for example be an autonomous inspection device for use in a potentially explosive atmosphere. It is for example possible that at least part of the housing is stationary mounted to support structure of inspection robot.

It is also conceivable that an optical unit is used instead of an optical sensor, wherein the optical unit is configured for transmitting and/or receiving light. The optical unit can for example be an optical transmitter and/or receiver. The invention therefore also relates to an inspection device for use in a potentially explosive atmosphere, comprising at least one substantially closed explosion-proof housing, said housing comprising at least one substantially translucent window for the transmission of light, at least one optical unit for transmitting and/or receiving light accommodated within said housing, at least one reflective element for reflection of light accommodated within said housing, and at least one drive unit accommodated within said housing, wherein the at least one reflective element is positioned such that said reflective element forms part of an optical path between the at least one window and the at least one optical unit, and wherein the optical unit is substantially stationary mounted in the housing, and wherein the drive unit is configured to move, and in particular to rotate, the at least one reflective element within said housing and with respect to the optical unit such that the optical path between the reflective element and the window can be adjusted with respect to the optical path between the reflective element and the optical unit.

The invention will be further elucidated herein below on the basis of the non- limitative exemplary embodiments shown in the following figures. Herein shows; figure 1 a a cross sectional view of a first possible embodiment of an inspection device according to the invention;

figure 1 b a perspective view of the inspection device as shown in figure 1 a;

figure 2a a cross sectional view of a second possible embodiment of an inspection device according to the invention;

figure 2b a perspective view of the inspection device as shown in figure 2a; and figure 2c an exploded view of the inspection device as shown in figures 2a and 2b.

Figure 1 a shows a cross sectional view of a first possible embodiment of an inspection device 101 according to the invention. Figure 1 b shows the inspection device 101 as shown in figure 1 a in a perspective view. Similar reference signs therefore correspond to similar or equivalent elements or features.

Figures 1 a and 1 b shown an inspection device 101 for use in a potentially explosive atmosphere. The device 101 comprises a thermally conductive, substantially pressure-resistant and substantially closed housing 102. The housing 102 comprises an optical sensor 103, in the shown embodiment a camera 103, a substantially translucent window 104, made of protective glass, for the transmission of light, a reflective element 105 for reflection of light, and a drive unit 106, in particular an electrical drive unit 106. The reflective element 105 and the window 104 are positioned such that environmental light emitted and/or reflected from the environment can pass through the window 104 and subsequently will be reflected by the reflective element 105 such that the environmental light can be received by the camera 103. A possible reflective path of a bundle of light emitted from the environment is indicated in the figure with an arrow. The camera 103 is

substantially stationary mounted in the housing 102. The electrical drive unit 106 is configured to move, and in particular to rotate, the reflective element 105 with respect to the camera 103 such that a tilting and/or panning effect of the camera 103 can be obtained while the camera 103 remains stationary with respect to the housing 102. The housing 102 comprises a substantially hollow, main body 107 wherein the camera 103, the reflective element 105 and the electrical drive unit 106 are received. The housing 102 furthermore comprises two closing elements 108a, 108b connected to the main body 107 for medium-tight sealing of the housing 102. A part of at least each closing element 108a, 108b is located within a volume enclosed by the main body 107. The closing elements 108a, 108b are fastened by means of multiple screws 109. A part of each closing element 108a, 108b furthermore engages an inner wall of the main body 107 of the housing 102.

Herewith are circumferential seams 1 10 formed between the inner wall of the main body 107 and the closing elements 108a, 108b. This circumferential seams 1 10 can also be referred to as flame paths 110. In the shown embodiment is the housing 102, and in particular the main body 107 generally substantially elongated, more in particular tubular. 17. The reflective element 105 comprises a mirror reflective surface 1 11 . The mirror reflective surface 1 11 is inclined with respect to a longitudinal axis of the housing 102, or a longitudinal axis of the camera 103. The mirror reflective surface 1 1 1 is coated with a layer of a noble metal, for example gold and/or silver. The translucent window 104 is releasably connected to the housing 104 by means of several screws 109. In the shown embodiment, which is best shown in figure 1 b, is the window 104 substantially elongated. The length direction of the window 104 is therewith substantially perpendicular to the length direction of the housing 102, and the camera 103. The reflective element 105 is configured to rotate with respect to an axis of rotation which is in line with a longitudinal axis of the camera 103 over at least 90 degrees, preferably at least 120 degrees and more preferably at least 180 degrees. In the shown embodiment is the electrical drive unit 106 a servomotor 106. The housing 102 is manufactured of a metal, in particular aluminium. The inspection device 101 as shown in figures 1 a and 1 b benefits from a relatively simple configuration.

Figure 2a shows a cross sectional view of a second possible embodiment of an inspection device 201 according to the invention. Figure 2b shows the inspection device 201 as shown in figure 1 a in a perspective view. Figure 2c shows the inspection device 210 as shown in figures 2a and 2b in an exploded view. Similar reference signs in these figures correspond to similar or equivalent elements or features.

Figures 2a-2c show an inspection device 201 for use in a potentially explosive atmosphere. The device 201 comprises a thermally conductive, substantially pressure-resistant and preferably substantially closed housing 202. The housing 202 comprises a body part 212 and a head part 213, wherein the head part 213 is movable, in particular rotatable, with respect to the body part 212. The body part 212 of the housing 202 comprises several grooves 218, resulting in the body part 212 being at least partially profiled. This may increase the heat-transferring capacity of the housing 202, as a result of which heat produced by the electrical drive unit 206 and/or the optical sensor 203, in particular the camera 203 unit can be relatively efficiently dissipated to the atmosphere surrounding the housing 202. The housing 202 furthermore comprises two closing elements 208a, 208b connected to respectively the head part 213 and the body part 212 for medium-tight sealing of the housing 102. Sealing and/or bearing rings 216 are used in the modular construction. The inspection device 201 comprises a camera 203 which is received in the body part 212 of the housing 202. The camera 203 is stationary mounted in the body part 212 of the housing 202 via a screw connection using a connection ring 215 and screws 209. The head part 213 comprises a substantially translucent window 204 of protective glass for the transmission of light. The head part 213 furthermore comprises a reflective element 205 for reflection of light and an electrical drive unit 206. The reflective element 205 and the electrical drive unit 206 are received in the head part 213. The reflective element 205 and the window 204 are positioned such that light emitted and/or reflected from the environment which can pass through the window 204 will be reflected by the reflective element 205 such that the light can be received by the camera 203. The electrical drive unit

206 is configured to move, and in particular to rotate, the head part 213 and therewith the reflective element 205 with respect to the body part 212 of the housing 202. Herewith a tilting and/or panning effect of the camera 203 can be obtained. The reflective element 205 is substantially stationary mounted in the head part 213 of the housing 202 such that moving, and in particular rotating of the head part 213 causes the reflective element 205 to move, and in particular to rotate with respect to the stationary mounted camera 203. The reflective element 205 comprises a mirror reflective surface 21 1 and is connected to head part 213 of the housing 202. The head part 213 of the housing 202 encloses at least part of the body part 212 of the housing 202. Figure 2c shows that the body part 212 of the housing 202 comprises a recess 214. During rotation of the head part 213 the window 204 is displaced within the recess 214. An inner wall of the head part 213 engages an outer wall of the body part 212, such that a circumferential seam 210 is formed between the inner wall of the head part 213 and the outer wall of the body part 212. This circumferential seam 210 can also be referred to as flame path 210, in particular rotating flame path 210. Further flame paths 210 are indicated in figure 2a as well. The electrical drive unit 206 is connected to both the body part 212 and the head part 213 of the housing 202. This is possible due to the longitudinal shape of the body part 212 which is at least partially enclosed by the head part 213. The camera 203 is a thermal imaging camera 203. The camera 203 comprises at least one infrared light source and wherein the reflective element 205 is configured for distributing the light of the supporting infrared light source. The device 201 is modularly constructed by means of several screws 209. The device 201 is configured to be connected to electric cables 217.

It will be apparent that the invention is not limited to the working examples shown and described herein, but that numerous variants are possible within the scope of the attached claims that will be obvious to a person skilled in the art. It is possible here to envisage that different inventive concepts and/or technical measures of the above described embodiment variants can be wholly or partially combined without departing from the inventive concept described in the appended claims. The verb“comprise” and conjugations thereof used in this patent publication are understood to mean not only“comprise”, but are also understood to mean the phrases“contain”,“substantially consist of”,“formed by” and conjugations thereof.

Claims

1. Inspection device for use in a potentially explosive atmosphere, comprising:

- at least one substantially closed explosion-proof housing, said housing

comprising:

o at least one substantially translucent window for the transmission of light,

- at least one optical sensor accommodated within said housing,

- at least one reflective element for reflection of light accommodated within said housing, and

- at least one drive unit accommodated within said housing,

wherein the at least one reflective element and the window are positioned such that environmental light transmitted through the window into said housing will be reflected by the reflective element in the direction of said at least one optical sensor, such that the environmental light can be received by the optical sensor, and

wherein the optical sensor is substantially stationary mounted in the housing, and wherein the drive unit is configured to move, and in particular to rotate, the at least one reflective element within said housing and with respect to the optical sensor such that the viewing angle of the optical sensor can be adjusted.

2. Inspection device according to claim 1 , wherein the housing is a modular housing, and wherein said housing comprises a main body enclosing an

accommodating space for the at least one optical sensor, the at least one reflective element, and the drive unit, wherein said main body is defined by at least one circumferential wall enclosing at least one wall opening, wherein each wall opening is substantially closed, preferably in a medium-tight manner, by at least one closing element of said housing.

3. Inspection device according to claim 2, wherein the main body is

substantially cylindrically shaped, and wherein each outer end opening of the substantially cylindrically shaped main body is substantially closed by a closing element of the housing.

4. Inspection device according to claim 2 or 3, wherein at least a part of at least one closing element is located within a volume enclosed by the main body.

5. Inspection device according to any of claims 2-4, wherein at least a part of at least one closing element engages an inner wall surface of the circumferential wall of the main body of the housing, preferably such that a circumferential seam is formed between the inner wall of the main body and the closing element.

6. Inspection device according to claim 5, wherein the width of the

circumferential seam is at least 10 millimetres, preferably at least 13 millimetres.

7. Inspection device according to any of claims 1 -4, wherein the interior of the substantially closed housing is filled with gas at an overpressure.

8. Inspection device according to any of the previous claims, wherein the housing comprises a body part and a head part co-acting with said body part, wherein the head part is movable, in particular rotatable, with respect to the body part, wherein at least one optical sensor is received in the body part, and wherein the head part comprises at least one window and wherein at least one reflective element is received in the head part, and wherein the drive unit is received in the body part and/or the head part and wherein the drive unit is configured to move, and in particular to rotate, the head part with respect to the body part.

9. Inspection device according to claim 8, wherein the reflective element is substantially stationary mounted in the head part of the housing such that moving, and in particular rotating of the head part causes the reflective element to move, and in particular to rotate with respect to the body part.

10. Inspection device according to claim 8 or 9, wherein the head part is configured to rotate with respect to an axis of rotation which is in line with a longitudinal axis of the body part of the housing over at least 90 degrees, preferably at least 120 degrees and more preferably at least 180 degrees.

1 1. Inspection device according to any of claims 8-10, wherein the head part of the housing encloses, in particular circumvents, at least a part of the body part of the housing.

12. Inspection device according to claim 1 1 , wherein an inner wall of the head part at least partially engages an outer wall of the body part.

13. Inspection device according to claim 12, wherein a circumferential seam is formed between the inner wall of the head part and the outer wall of the body part.

14. Inspection device according to any of claims 8-13 , wherein the unit is connected to both the body part and the head part of the housing.

15. Inspection device according to any of claims 8-14, wherein the length of the head part of the housing is smaller than the length of the body part of the housing.

16. Inspection device according to any of the previous claims, wherein the optical sensor is a camera, in particular a thermal imaging camera.

17. Inspection device according to claim 16, wherein the camera comprises at least one infrared light source and wherein the reflective element is configured for distributing the light of the supporting infrared light source.

18. Inspection device according to claim 16 or 17, wherein the camera is configured for real time monitoring.

19. Inspection device according to any of the previous claims, wherein the reflective element comprises at least one mirror reflective surface which, preferably has a substantially flat and/or angled and/or curved shape.

20. Inspection device according to claim 19, wherein at least a part of the mirror reflective surface is inclined with respect to a longitudinal axis of the housing, in particular of the body part of the housing.

21. Inspection device according to claim 19 or 20, wherein the mirror reflective surface is coated with a metallic coating, in particular gold and/or silver.

22. Inspection device according to any of the previous claims, wherein the translucent window is releasably connected to the housing by means of several screws.

23. Inspection device according to any of the previous claims, wherein the substantially translucent window is made of protective glass.

24. Inspection device according to any of the previous claims, wherein the substantially translucent window is made of sapphire glass.

25. Inspection device according to any of the previous claims, wherein the reflective element is configured to rotate with respect to an axis of rotation which is in line with a longitudinal axis of the optical sensor over at least 90 degrees, preferably at least 120 degrees and more preferably at least 180 degrees.

26. Inspection device according to any of the previous claims, wherein the drive unit is an electrical drive unit, and in particular a servomotor.

27. Inspection device according to any of the previous claims, wherein the housing is thermally conductive.

28. Inspection device according to any of the previous claims, wherein the housing is at least partially, and preferably entirely manufactured of a metal, in particular aluminium.

29. Inspection device according to any of the previous claims, wherein the housing is configured to be connected to at least one electric cable.

30. Mobile inspection robot for use in a potentially explosive atmosphere comprising at least one inspection device according to any of the previous claims.

31 . Mobile inspection robot according to claim 30, wherein at least part of the housing is stationary mounted to support structure of inspection robot.