LIGHT GUIDING ARRANGEMENT, SPARK AND/OR FLAME DETECTOR AND FIRE PROTECTION SYSTEM

Abstract

The present invention relates to a light guiding arrangement (1) for transmitting electromagnetic radiation, in particular ultraviolet and/or infrared radiation, and a spark and/or flame detector that uses same. The light guiding arrangement (1) comprises a housing (10) and a light guiding rod (20), wherein the housing (10) has a light entrance opening (12) and a light exit opening (14) situated opposite, wherein the light guiding rod (20) is arranged in the housing (10) between the light entrance opening (12) and the light exit opening (14), wherein the light guiding rod (20) is mounted resiliently on at least one side in the housing (10).

Claims

1. A light guiding arrangement for transmitting electromagnetic radiation, the light guiding arrangement comprising: a housing and a light guiding rod, wherein the housing has a light entrance opening and an opposite light exit opening, wherein the light guiding rod is arranged in the housing between the light entrance opening and the light exit opening, and wherein the light guiding rod is resiliently mounted on at least one side in the housing.

2. The light guiding arrangement as claimed in claim 1, wherein the resilient mounting is designed as mounting in the axial direction of the light guiding rod on the side opposite the light entrance opening.

3. The light guiding arrangement according to claim 1, wherein an air gap is formed between the light guiding rod and the housing in the axial direction of the light guiding rod, wherein the air gap is preferably between 0.2 mm and 5 mm.

4. The light guiding arrangement as claimed in claim 1, further comprising a protection optical unit arranged in front of the light guiding rod at the light entrance opening.

5. The light guiding arrangement as claimed in claim 4, wherein the housing has a thread in the region of the light entrance opening, and the protection optical unit is embodied to be screwed onto the housing.

6. The light guiding arrangement as claimed in claim 1, wherein, in the region of the light entrance opening, a fixing element for a protection optical unit is formed in the form of beading, and/or the light guiding arrangement has elastic mounting in the radial direction around the light guiding rod.

7. The light guiding arrangement as claimed in claim 5, wherein a tolerance ring is mounted in a floating manner between the protection optical unit and the housing or light guiding rod.

8. The light guiding arrangement as claimed in claim 1, wherein the housing has cooling fins, on its outside in the axial direction.

9. The light guiding arrangement as claimed in claim 1, wherein the light guiding rod consists of sapphire and/or the housing consists of stainless steel.

10. The light guiding arrangement as claimed in claim 1, wherein a receptacle for receiving a sensor head of a flame and/or spark detector is formed in the region of the light exit opening.

11. The light guiding arrangement as claimed in claim 1, wherein the light guiding arrangement is embodied for coupling optical radiation and an electronic or sensor system.

12. The light guiding arrangement as claimed in claim 11, wherein the light guiding arrangement is embodied for use in regions with challenging environmental influences including at least one of high temperatures, high voltages, strong electromagnetic interference radiation and radioactivity, aggressive atmospheres including acids and bases, confined spaces, and explosive atmospheres.

13. The light guiding arrangement as claimed in claim 1, wherein the light guiding arrangement is embodied for guiding light in the wavelength range from 0.2 to 6 micrometers.

14. The light guiding arrangement according to claim 1, wherein the light guiding arrangement has an air gap that radially surrounds the light guiding rod, between the light guiding rod and the housing, wherein the light guiding arrangement has an air inlet device, which is set up to introduce air into the air gap between the light guiding rod and the housing.

15. A spark and/or flame detector for use with fire alarm and/or extinguishing control centers, comprising: a light guiding arrangement as claimed in claim 1, and a sensor head, wherein the sensor head is set up for being coupled to the light exit opening of the light guiding arrangement.

16. A fire protection system for detecting sparks and/or flames, comprising: a spark and/or flame detector as claimed in claim 15, and an evaluation unit.

17. The fire protection system as claimed in claim 16, further having a unit that dispenses extinguishing agent and/or a protection apparatus, wherein the unit that dispenses extinguishing agent is controlled by the evaluation unit and/or a central control unit.

18. The fire protection system as claimed in claim 16, wherein the fire protection system is designed as a spark extinguishing system, and the evaluation unit and/or a central control unit is embodied as part of a spark alarm center.

19. A method for thermal decoupling of at least one sensor of a spark and/or flame detector from the detection location of the electromagnetic radiation characteristic of sparks or flames, including the steps of: providing a light guiding arrangement for transmitting electromagnetic radiation, wherein the light guiding arrangement has a housing and a light guiding rod, wherein the housing has a light entrance opening and an opposite light exit opening, wherein the light guiding rod is arranged in the housing between the light entrance opening and the light exit opening, guiding electromagnetic radiation from the light entrance opening to the light exit opening by the light guiding rod, and detecting the electromagnetic radiation by at least one sensor after the electromagnetic radiation has emerged from the light exit opening.

20. The method as claimed in claim 19, wherein an air gap is formed between the light guiding rod and the housing in the axial direction of the light guiding rod, wherein the air gap is between 0.2 mm and 5 mm, wherein the method includes the following step: influencing the air in the air gap by an air inlet device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Further advantages and special configurations will be described below with reference to the accompanying figures. In the figures:

[0062] FIG. 1 shows, schematically and by way of example, a light guiding arrangement in cross section,

[0063] FIG. 2 shows, schematically and by way of example, a top view of a sensor head for spark detection,

[0064] FIG. 3 shows, schematically and by way of example, a top view of a sensor head for flame detection,

[0065] FIG. 4 shows, schematically and by way of example, a spark or flame detector in several views,

[0066] FIG. 5 shows, schematically and by way of example, an embodiment of a housing of the light guiding arrangement,

[0067] FIG. 6 shows, schematically and by way of example, a fire protection system, and

[0068] FIG. 7 shows, schematically and by way of example, a flowchart of a method.

MODE(S) FOR CARRYING OUT THE INVENTION

[0069] FIG. 1 shows, schematically and by way of example, a light guiding arrangement 1 in cross section. The light guiding arrangement 1 is set up to guide light, in particular ultraviolet, infrared, and/or temperature radiation, from a light entrance opening 12 to a light exit opening 14.

[0070] The light guiding arrangement 1 comprises a housing 10, in the interior of which a light guiding rod 20 is resiliently mounted. To mount the light guiding rod 20, the light guiding arrangement 1 has a spring element 32, a spring element 34, and a spring element 36. It should be noted here that the spring elements 32, 34, 36 shown by way of example can also be embodied differently, for example only a single spring element may be provided.

[0071] The spring elements 32, 34 and 36 allow the light guiding rod 20 to expand relative to the housing 10 without stresses occurring. In addition, the usually highly sensitive light guide of the light guiding rod 20 is protected by its mounting. It is known that different materials, in the present case for example the light guiding rod 20 and the housing 10, expand to different extents when heated, which can lead to stresses. This effect can be compensated for by the resilient mounting.

[0072] An air gap of 0.2 mm to 5 mm is preferably provided between the light guiding rod 20 and the housing 10. Air, in particular compressed air, can be introduced into the air gap by means of an air introduction device (not shown). The compressed air improves cooling of the light guiding rod 20 or the light guiding arrangement 1.

[0073] The spring element 32 is arranged in the region of the light entrance opening 12 and is held in position for example by means of a tolerance ring 38. The tolerance ring 38 is in turn fastened via a fixing device, for example a thread 16 with which a protection optical unit 40 is fixed. The protection optical unit 40 has a window element 42, which is optically transparent to corresponding wavelengths and is embodied, for example, in the form of a lens or disk.

[0074] The protection optical unit 40 can accordingly be mounted reversibly, in particular be able to be unscrewed, and can thus be easily changed in the event of contamination or damage. In this example, the window element 42 is held with a beading 44 of the protection optical unit 40.

[0075] The spring element 34 is received in a groove, for example, so that it makes resilient mounting of the light guiding rod 20 in the radial direction possible. The position of the spring element 34 in the axial direction along the light guiding rod 20 is fixed by means of the groove. Finally, the spring element 36 is arranged on the side of the light exit opening 14 and preferably resiliently mounts the light guiding rod 20 in the axial direction.

[0076] On the side of the light exit opening 14, there is a receptacle 15 for receiving a sensor head, in particular for reversibly receiving a sensor head, for example a flame and/or spark detector, as will be described in detail later with reference to FIGS. 2 to 4. In conjunction with a sensor head, the light guiding arrangement 1 forms a spark and/or flame detector.

[0077] One or more cooling elements 18 is or are preferably arranged on the outside of the housing 10. The cooling elements 18 improve heat dissipation from the housing 10.

[0078] The light guiding arrangement 1 according to the invention makes the detection of infrared radiation in an application range of up to 450° C., for example, possible, wherein cooling to a maximum operating temperature of a sensor head accommodated in the receptacle 15 is achieved over the course of the light guiding arrangement 1 in the axial direction.

[0079] In the example in which the sensor is a silicon element that can withstand a temperature of at most 100° C., cooling from 450° C. by ΔT, equal to 350 K, takes place. The length of the light guiding rod 20 is the result of the cooling required, which means that shorter light guiding rods 20 are possible for lower temperature differences to be achieved.

[0080] The thermal conductivity of the light guiding rod 20 and of the enclosing housing 10 also have an influence on the minimum length. The lower the thermal conductivity is, the shorter can be the light guiding rod 20. The cooling of the light guiding rod 20 by the housing 10, in particular by cooling elements 18 arranged on the surface, and also the ambient conditions, such as still air, moving air, and the temperature within this surrounding area, are also determined.

[0081] The following table gives some examples of suitable materials for light guides as light guiding rod 20, as housing 10 or as sensor and their ranges of application. Of course, other materials suitable as light guides, housings, and sensors are also possible:

TABLE-US-00001 Operating Thermal Wavelength range temperature conductivity Expansion (transmission >50%) range Material Use (W/(m*K)) coefficient (nm) (° C.) Sapphire Light guide  40 @ 25° C.  5.6*10.sup.−6/K.  300 . . . 5500 >1000 12 @ 400° C. Borosilicate Light guide 1.2  3.3*10.sup.−6/K.  350 . . . 2500 500 glass Quartz glass Light guide 1.38 0.54*10.sup.−6/K.  170 . . . 3500 1000 Stainless steel Housing 16   16*10.sup.−6/K. — 450 . . . 850 Titanium Housing 22  8.6*10.sup.−6/K. — 550 Aluminum Housing 220 23.8*10.sup.−6/K. — 250 Brass Housing 123   21*10.sup.−6/K. — 250 Silicon element Detector — —  220 . . . 1100 −40 . . . 100 PbS Detector — — 1000 . . . 3000 −40 . . . 65  PbSe Detector — — 1000 . . . 4700 −40 . . . 85  InGaAs Detector — —  900 . . . 1700 −40 . . . 85  Pyrodetector Detector — —   200 . . . 25000 −40 . . . 85  UV sensor Detector — — 180 . . . 280 −40 . . . 125

[0082] Materials with a low thermal conductivity are better suited for thermal decoupling. For example, sapphire is suitable as the material of the light guiding rod 20 only for a temperature difference ΔT of approx. 200 K with a length of 10 cm and a diameter of 20 mm. Here, a stainless steel case as the housing 10 and still air is assumed. For high temperature applications up to a temperature difference ΔT of 350 K, borosilicate glass or quartz glass is preferably used.

[0083] For the decoupling of broadband wavelengths, for example in the case of flame detection with pyrodetectors, sapphire is preferably used as the material of the light guiding rod 20.

[0084] The cooling can be improved by the targeted introduction of air, for example a feed of compressed air, into the air gap between the light guiding rod 20 and the housing 10. In this case, cold air is preferably introduced in the vicinity of the receptacle 15, i.e. in the vicinity of the detector, and is discharged in the hot region, i.e. in the region of the light entrance opening 12.

[0085] As already mentioned, the light guiding rod 20 is mounted in a floating manner since, were it to come into contact with the housing 10, its refractive index would change at a cylindrical surface of the light guiding rod 20, which is embodied to be cylindrical for example, and thus the light guidance would be impaired. Alternatively, it would be conceivable to render the cylindrical surface reflective, although this requires a more complex implementation. The floating mounting is also necessary to protect the fragile light guiding rod 20.

[0086] In a very specific exemplary embodiment, the light guiding rod 20 is between 75 mm and 1500 mm long and has a diameter of 5 mm to 25 mm. Larger diameters, in particular from 10 mm to 25 mm, particularly include the case in which optics monitoring is provided, see FIGS. 2 and 3.

[0087] It is known that, for example, in pneumatic conveyors for materials such as flour or chips, foreign particles such as stones can lead to the generation of sparks.

[0088] The present invention provides the light guiding arrangement 1, which is utilizable in a spark alarm and/or flame alarm.

[0089] Compared with quartz, sapphire as the material of the light guiding rod 20 has a greater transmission, but must be better protected against vibrations. For this purpose, the tolerance rings 38 can be formed, for example, with an accordion-like shape. Spring elements or tolerance rings made of rubber materials are typically not possible due to the high temperatures that occur.

[0090] In contrast to known light guiding arrangements, in particular the surface area for sensors that is available in the region of the light exit opening 14 is large enough to accommodate the entire area of the sensor or sensors.

[0091] In the light guiding arrangement 1 shown in FIG. 1, the resilient mounting absorbs the different expansions and the impacts.

[0092] FIG. 2 shows, schematically and by way of example, a top view of a sensor head 100, which is embodied to be received in the receptacle 15 shown in FIG. 1. The surface shown is intended to be arranged at the light exit opening 14 in a mounting position, that is to say to be arranged in contact with it or in the vicinity thereof. An insertion region 115 is formed here for arrangement within the receptacle 15.

[0093] A first sensor 50 and a second sensor 60 can be seen, which are coupled to the light guiding rod 20 in the mounting position. The first sensor 50 can be, for example, a sensor for optics monitoring, which is arranged to monitor whether visibility through the light guiding rod 20 is ensured.

[0094] The second sensor 60 can be the sensor that ultimately detects the spark and/or the flame. It should be noted that the diameter of the light guiding rod 20 may be smaller if the first sensor 50 is dispensed with. The arrangement of both the first sensor 50 and the second sensor 60 improves the reliability of a spark and/or flame detector 2, which is shown in full in FIG. 4.

[0095] The sensor head 100 furthermore has an electronic system 120 (not shown in more detail). In the simplest case, the electronic system 120 is not actually an electronic system at all, but merely set up to pass on signals of the sensors 50, 60 to an evaluation electronic system, for example a fire alarm and/or extinguishing control center, cf. FIG. 6. Alternatively, the data or signal processing can also be carried out partially or completely in the sensor head 100.

[0096] The embodiment of FIG. 2 is, for example, a sensor head 100 of a spark alarm, since the second sensor 60 is designed as a single sensor for detecting a specific wavelength that is characteristic of sparks.

[0097] FIG. 3 shows, schematically and by way of example, a top view of a further sensor head 100. In this example, the second sensor 60 has three narrowband sensor elements 62, which preferably capture three different wavelengths of the optical radiation. This configuration is preferably designed for a flame alarm.

[0098] The sensor head 100 has a housing 110, which comprises means for mounting the sensor head 100 in the receptacle 15. For example, the connection can be made by a form fit, in the form of a bayonet lock, cf. FIG. 5, or by other types of connection.

[0099] It should be noted that the sensor head 100 is preferably screwed into the receptacle 15. It is thus possible to design the light guiding arrangement 1 according to the invention both as a spark alarm and as a flame alarm and, in a further embodiment, also as a combined spark and flame alarm. For this purpose, for example a thread can be provided in the receptacle 15 and the housing 110 can have a corresponding thread. Other types of fixation are, of course, also conceivable.

[0100] FIG. 4 shows, schematically and by way of example, different views of a spark and/or flame detector 2, which has a light guiding arrangement 1 and a sensor head 100 received in the receptacle 15. A connection cable 70, which is designed to be flexible, makes the transmission of data from the sensor head 100 to an evaluation device, in particular a fire alarm and/or extinguishing control center, possible. Cooling fins 18 are shown arranged on the housing 10. The housing 10 is designed to be rigid in order to stabilize the light guiding rod 20.

[0101] FIG. 5 shows, schematically and by way of example, part of the housing 10 of a light guiding arrangement 1, specifically the part of the receptacle 15. In the special configuration of FIG. 5, the receptacle 15 has slotted link guides 19 for fastening a sensor head 100, which has corresponding coupling means. Of course, other types of fixation are also possible.

[0102] As an alternative to the embodiment of the receptacle 15 as a receptacle, that is to say as a socket, the receptacle 15 can also be designed as a plug, and the corresponding receptacle can be formed on the side of the sensor head 100. Accordingly, the sensor head 100 can also have the suitable coupling means, for example slotted link guides.

[0103] FIG. 6 shows, schematically and by way of example, a fire protection system 5 according to the invention. In this example, the fire protection system 5 has an evaluation unit 4, embodied in the form of a fire alarm and/or extinguishing control center, which is connected to a plurality of spark and/or flame alarms 2 via connecting lines 70. The evaluation unit 4 is in particular the central control unit of the fire protection system 5. As a further example, a separate evaluation unit 4′ is shown, which is arranged between the spark and/or flame alarm 2 and the fire alarm and/or extinguishing control center and evaluates and passes on the detection signals of the spark and/or flame alarm 2.

[0104] The light entrance opening of, in this example, two spark and/or flame alarms 2 is located in a monitoring region 6, which is, for example, the interior of a material dryer. Furthermore, a device that dispenses extinguishing agent and/or a protection apparatus 9, for example an extinguishing nozzle or another device, is shown. In the configuration as a device that dispenses extinguishing agent, it is designed to dispense extinguishing agent into the monitoring region 6 when controlled accordingly. Examples of protection apparatuses are material dispensing flaps or power cut-off apparatuses. A device that dispenses extinguishing agent can be configured as desired and as is known to a person skilled in the art and can comprise, for example, an extinguishing agent storage container, a triggering device, a pipeline system, and/or an extinguishing nozzle.

[0105] FIG. 7 shows, schematically and by way of example, a flowchart of a method 200 for thermal decoupling of at least one sensor 50, 60 of a spark and/or flame detector 2 from the detection location of the electromagnetic radiation that is characteristic of sparks or flames.

[0106] In a step 210, a light guiding arrangement 1 for transmitting electromagnetic radiation, in particular ultraviolet and/or infrared radiation, is provided. The light guiding arrangement 1 has a housing 10 and a light guiding rod 20. The housing 10 has a light entrance opening 12 and an opposite light exit opening 14. The light guiding rod 20 is arranged in the housing 10 between the light entrance opening 12 and the light exit opening 14.

[0107] In a step 220, electromagnetic radiation is guided from the light entrance opening 12 to the light exit opening 14 by means of the light guiding rod 20.

[0108] In a step 230, the electromagnetic radiation is detected by the at least one sensor 50, 60 after the electromagnetic radiation has emerged from the light exit opening 14.

[0109] Finally, in an optional step 240, the air in an air gap between the light guiding rod 20 and the housing 10 is influenced in particular by means of an air introduction device (not shown).

LIST OF UTILIZED REFERENCE SIGNS

[0110] 1 Light guiding arrangement [0111] 2 Spark and/or flame detector [0112] 4 Central control unit [0113] 4′ Evaluation unit [0114] 5 Fire protection system [0115] 6 Monitoring region [0116] 9 Device that dispenses extinguishing agent and/or protection apparatus [0117] 10 Housing [0118] 12 Light entrance opening [0119] 14 Light exit opening [0120] 15 Receptacle [0121] 16 Thread [0122] 18 Cooling elements [0123] 19 Slotted link guides [0124] 20 Light guiding rod [0125] 32 Spring element [0126] 34 Spring element [0127] 36 Spring element [0128] 38 Tolerance ring [0129] 40 Protection optical unit [0130] 42 Window element [0131] 44 Fixing element [0132] 50 First sensor [0133] 60 Second sensor [0134] 62 Sensor element [0135] 70 Connection cable [0136] 100 Sensor head [0137] 110 Housing [0138] 115 Insertion region [0139] 120 Electronic system [0140] 200 Method [0141] 210 Provision step [0142] 220 Guiding step [0143] 230 Detection step [0144] 240 Influencing step