EP2043068B1 - Device for monitoring a fire alarm and configuration method and fire alarm - Google Patents

Abstract

The device has a sensor (2) for sensing an object of a fire alarm (1), and a data storage and an evaluation unit for storing and evaluating a sensor signal. The fire alarm is activated by smoke, fire gas or heated air. The evaluation unit is formed to determine a value from the sensor signal for current shield of the fire alarm and for triggering an alarm when the determined value approaches a stored expected value. The value is determined depending on a horizontal angle over which the sensor senses the object. An independent claim is also included for a configuration process for monitoring a fire alarm.

Description

The invention relates to a responsive to smoke, a fire gas or air heating fire detector with a sensitive for objects in the vicinity of the fire detector sensor.

Such fire detectors usually have a measuring chamber for smoke or combustion gases. In it, a sensor measures the absorption or scattering of smoke particles from light from a light source emitting light. Likewise, optoacoustic methods are known in which the change in sound is measured by fire gases heated by a laser. Fire detectors often measure the air heating caused by a fire as an alternative or in addition to a temperature sensor. Also, combustion gases can be determined by means of a sensitive semiconductor structure.

In the fire detector, a safe and precise detection of a fire is possible. In the case of a scattered light detector, interference from ambient light is minimized by a darkened measuring chamber. This allows a cost-effective design and provides great reliability. On the other hand, such a measuring chamber inevitably has the disadvantage that the smoke or the combustion gas can penetrate only delayed and the density in the interior of the measuring chamber at best asymptotically reaches the value of the external concentration. As a result, the detection of a fire is more or less delayed. In addition, ambient dust can quickly contaminate the measuring chamber. The fire detector must then be cleaned or replaced frequently. A solution for this can be suitable filters. at so-called forced-ventilated fire alarms, the fire detector is supplied via pipelines coming from a monitoring room air.

Other known fire detect smoke outside of their housing and can in particular also perceive objects in their environment. For example, in the European patent application EP 1783712 A1 the absorption of self-generated and reflected back to objects to the fire detector infrared radiation has been described by smoke particles below the fire detector. In order to detect the interference of objects moving in the beam path which absorb or reflect infrared radiation, the distance to the reflecting objects is also measured by means of the same sensor. This distance measurement can, for example, according to that in the European patent application EP 1391860 A1 disclosed principle. It describes a reflector mounted on the side of the fire detector near the ceiling. The fire detector generates a modulated infrared radiation, which is at least partially absorbed by smoke particles in the beam path between fire detector and reflector. To distinguish objects located in the beam path, the fire detector determines its distance via the phase shift of the reflected radiation.

Fire detectors, or the pipes of a forced-ventilation fire detector, must be placed expertly in the room so that the fire can be detected safely and in good time. Fire detectors are typically attached to a pedestal that is high in the room, often on the ceiling. For a long time it has been a recognized disadvantage that changes in space can affect fire detection. Examples of such changes are the division of space through a partition and moving a tall cabinet. As a rule, such changes can not be detected by the fire detector, not even by those fire detectors that detect smoke outside of their housing and perceive objects, as the relevant objects are not necessarily placed in the measuring range of their sensor. This requires regular and costly maintenance. Although proposes the European patent application EP 1191496 A1 In the case of a fire detector, provide an additional ultrasonic transmitter and an additional ultrasonic sensor to determine "if there is a foreign object in an area around the smoke detector that might affect the flow conditions for fire detection." This can be output as a warning from the control panel. However, it is not disclosed in which area around the smoke detector the foreign object is sought, nor with which device structure it is detected, nor according to which criteria its influence on the fire detection is to be assessed. The embodiments in the European patent application EP 1191496 A1 show useless measuring areas, immediately below the fire detector and concentrated in a vertical plane. No algorithm for the evaluation is described to distinguish in this sense obstructive from non-interfering foreign body.

An object of the invention is to reliably, selectively and simply evaluate the influence of changes in space on such a fire detector.

The object is achieved in each case by the subject matters of the independent claims. Further developments of the invention are specified in the subclaims.

A core of the invention is that in a properly oriented fire detector, the sensor for objects laterally the fire detector is sensitive to the vertical within any circular section of 150 °, preferably within any sector of 110 °. These circular sections of the horizontal plane extend in every direction from the fire detector. The sensor should thus detect objects in or near the horizontal plane around the fire detector. It is also conceivable that the fire detector does not monitor the entire horizon, but omits gaps in which small and distant objects disappear. In this case, no monitoring gap may be greater than such a circular section. It has been shown according to the invention that monitoring by detection of objects that are located laterally of the fire detector and, depending on the type of fire detector and application, size and proximity, is reliable, selective and easy. Only such items can place the fire detector in the shadow of the airflow from the fire, and the fire alarm can easily distinguish it from harmless objects. False alarms are largely avoided.

Preferably, a suitable sensor for a fire characteristic at the same time also forms the sensor for objects. Under certain circumstances, however, a special sensor, for example an ultrasonic sensor, is required.

In an advantageous embodiment, this sensor for objects on the side of the fire detector on at least one level is more sensitive than below at even distance to the fire alarm. Furthermore, it is advantageous that the sensor above the depth angle of 20 °, measured from the horizontal plane, is sensitive, advantageously even at the height of the fire detector. If the sensitivity of the sensor near the ground and outside of the measuring area of the fire detector is low, filtering out local, irrelevant objects requires less computing power.

In a further advantageous embodiment, the fire detector comprises at least one transmitter for emitting electromagnetic, acoustic or other radiation in the sensitivity range of the sensor. This allows a more accurate and less environmentally dependent measurement.

In a next advantageous embodiment, the fire detector comprises a deflection means for radiation in the sensitivity range of the sensor. The deflection means is designed to deflect such radiation from a location in the fire detector to objects laterally of the fire detector, or vice versa, in a fire detector which is oriented as intended. The fire detector has at this location one or more transmitters, one or more sensors, or a combination of both. The deflection means may be, for example, an optical unit such as a lens or a mirror. By means of a deflection means with a drive, a sensor for smoke below the fire detector could at least temporarily also be used as a sensor for objects laterally thereof.

The invention also relates to a device for monitoring a fire detector, which has at least one responsive to smoke, a fire gas or air heating fire detector with a sensitive for objects laterally of the intended fire detector sensor, and is equipped with a data memory and with an evaluation unit for the sensor signal , The data memory and the evaluation unit are integrated, for example, in a freestanding fire detector or partially or entirely in other units of a fire detection system, such as in a fire alarm system, added. Although the processing of the sensor signal in a system loads the same Communication network with additional traffic, but allows free resources to use.

The inventive device is based on the recognition that a reliable, selective and easy monitoring of a fire detector based on position, size and proximity of the objects in its environment is possible. The evaluation unit is designed to determine from the sensor signal a value for the flow shield of the fire detector by objects and to trigger a warning message if the determined value approaches a stored expected value for a flow shield. This value is advantageously determined as a function of the horizontal angle over which the sensor senses the objects, and preferably the stored expected value corresponds to an angle of at least 20 °. In another example, the flow shield is evaluated separately by the size and solid angle of the objects laterally of the fire detector. The evaluation unit triggers a warning message if these values exceed the empirical values stored at the same time. In a similar alternative, the evaluation unit is designed to determine from the sensor signal a value for the surface of objects facing the fire detector and to trigger a warning message if the determined value approaches a stored expected value for the surface of a partition wall.

In an advantageous embodiment of the invention, the value is determined from the size of the sensor signal. In this case, it is preferable to select the sensitivity range of the probe such that all other expected object materials produce an approximately identical sensor signal magnitude for the same other circumstances. If the fire detector is then equipped with a corresponding radiation source, the intensity of the reflections, for example, is decisive, since this one Conclusion on the solid angle of the object allows, and thus on its ability to shield the fire detector of air currents from a fire. Another possibility is the passive ambient light detection, which can only take place reliably with good information about the room lighting at any time or in certain time frames. In a further alternative, a transmitter of the fire detector emits radiation pulses in the horizontal plane. The evaluation unit then integrates a function of the received sensor signal over time. In this case, preferably within a received reflection pulse later arriving radiation, as well as radiation from a weak transmission or unsensible reception angle, heavier weighted.

In a further advantageous embodiment, the value is determined by checking whether it is consistent with permanently present objects. For example, it must remain reasonably stable over a period of time, possibly within a stored inaccuracy of measurement. For example, where it is to be expected that, for example, craftsmen often hang large bundles of cables from the ceiling, a series of measurements can even be carried out over several hours or, depending on local regulations and standards, up to several weeks.

In a next advantageous embodiment, the value is determined on the basis of a determination of the value for the distance of the fire detector to objects. The distance results, for example, by a radiation transit time measurement. In the case of infrared radiation or other light, this requires a special photodiode and complex electronics for the detection of relative distances of one tenth of a centimeter. At high sensitivity, the photodiode must have a time resolution well below a nanosecond. Another possibility is the distance measurement by means of the Phase shift of the reflection of an amplitude-modulated light.

In advantageous embodiments, the fire detector comprises a plurality of sensors sensitive to objects in complementary directions, or multiple transmitters of electromagnetic, acoustic or other radiation in the sensitivity range of the sensor which irradiate objects in complementary directions. From the number and type of sensors that receive a signal, conclusions about the flow shield of the fire detector can be closed by objects. Namely, a direct, albeit inaccurate value for the viewing angle of the object is determined from the perspective of the fire detector. It is conceivable according to the invention that several transmitters are also actuated one after the other in order to determine the direction and distance of the objects by comparison.

According to the invention, the warning message is different from a fire alarm, so that measures to compensate for the changes in the room are taken without unnecessary excitement.

The invention also relates to a configuration method in which at least one fire detector responding to smoke, a fire gas or air heating is expertly placed with a sensor sensitive to objects on the side of the fire detector, and in which a data memory and an evaluation unit for the sensor signal are operated. According to the invention, in each case an object with a different material composition, size or distance is placed laterally of the fire detector, a smoke, combustion gas or hot air oven is operated and the response time of the fire detector is determined and evaluated. Due to the determined and rated response times, an expected value for a flow shield of the fire detector is determined by objects. This expectation becomes finally stored in a data storage to an evaluation of such to be configured fire detectors.

Figur 1

einen erfindungsgemäßen Brandgasmelder in einem Raum mit einem Brandherd und mit einem Gegenstand, welcher eine Strömungsabschirmung für die daraus entweichenden Brandgase bildet,

Figur 2

einen erfindungsgemäßen Rauchmelder im Querschnitt,

Figur 3

eine Betätigungspuls zum Sender eines erfindungsgemäßen Rauchmelders und das resultierende Fühlersignal über die Zeit, und

Figur 4

einen weiteren erfindungsgemäßen Rauchmelder im Querschnitt.

The invention will be explained in more detail with reference to exemplary embodiments illustrated in the figures. It shows

FIG. 1

a fire gas detector according to the invention in a room with a fire and with an object which forms a flow shield for the escaping combustion gases,

FIG. 2

a smoke detector according to the invention in cross section,

FIG. 3

an actuating pulse to the transmitter of a smoke detector according to the invention and the resulting sensor signal over time, and

FIG. 4

another smoke detector according to the invention in cross section.

The FIG. 1 To the fire gas detector housing around ten horizontally aligned sensor diodes 2 are arranged, each with adjacent LEDs 3. It was subsequently installed a 190 centimeters wide and 45 centimeters high billboard 4 to 15 centimeters from the fire gas detector. The arrows indicate how the fire gases originating from a fire 5 ascend, at the same time cooling down, and then flow away laterally under the fire gas detector 1 because of the billboard 4. Only after a long diffusion process can the fire gas detector 1 detect it.

The FIG. 2 shows a smoke detector 11 according to the invention in cross section. Its housing consists of a base plate 112, equipped with fastening means, not shown, for mounting on a pedestal, and from a transparent to infrared radiation cover 113. In the housing, a circuit board 114 with including a photodiode with integrated lens 16 and a LED 13A mounted. Thus, the smoke detector 11 can perceive smoke particles near its housing by means of infrared radiation.

In addition, a second LED 13B and a second photodiode 12 are located on the circuit board 114. Alternately to the smoke particle measurement, the fire detector 1 regularly evaluates any objects in its vicinity. For this purpose, both LEDs 13A and 13B are briefly actuated, that is, pulsed, for example. A guard ring 17 mounted around the second photodiode 12 prevents its infrared radiation from being directly received therethrough. Instead, a portion of this radiation is deflected by a reflective coating for them 18 on a cone-like thickening of the lid 113 to the side of the fire detector 1, there possibly reflected by objects and received via the coating 18 in the second photodiode 12. On the circuit board and a microprocessor and a data memory are applied, which are not shown. A running on the microprocessor program forms an evaluation unit for the sensor signal.

The FIG. 3 shows an actuation pulse 131 to the transmitter of a fire detector according to the invention and the resulting sensor signal 121 over time. The actuation voltage is several orders of magnitude higher than the resulting sensor signal voltage. The structure of the fire detector corresponds to that of the fire detector 11 in FIG. 2 , Its photodiode 12 and electronics have a very high capacity for time resolution. Its LEDs 13A and 13B simultaneously transmit a pulse of infrared radiation for the purpose of distance measurement, the reflections of which are received by the photodiode 12. From the unitary shape of the sensor signal 121 can be concluded on a single object within the monitored area. The Evaluation unit determines the time delay 141 of the received reflections and calculates therefrom the shortest distance to the object.

Thereafter, the LEDs 13A and 13B each send one pulse of infrared radiation behind each other. Since in each case the emission intensity of the coating 18 is different direction-dependent, and the deflection factor of reflections through the coating 18 to the photodiode 12 as well, the evaluation unit can calculate from a comparison of the resulting, not shown sensor signals of the photodiode 12, in which angles to the plane of symmetry of Fire detector the reflections from the object at any time at the photodiode 12 arrive. Thus, rudimentary information about the direction and solid angle of the article is obtained, which later enables compensating the directional emission intensity of the LEDs 13A and 13B from the coating 18.

Now the evaluation unit can accurately determine a value for the flow shield of the fire detector 11 through the object by multiplying a pulse of the sensor signal 121 by a polynomial winding of time, integrating the product over time and dividing the integral by the distance: flow shield = ∫ Sensor signal (t) * [a + b * t + c * t ² + d * t ³ + ...] dt / distance. The polynomial winding is preferably predominantly second order (c> a, b, d, ...) in order to account for the intensity loss due to the different signal path length. However, the polynomial winding also contains additional knowledge based components based on experience (b, d,... 0) for the direction-dependent emission intensity of the LEDs 13A and 13B via the reflective coating 18 and for the non-uniform deflection through the coating 18 to the photodiode 12 compensate. Since it is well known from Thus, the evaluation unit compensates for the direction-dependent influence of the coating 18 at which angles the reflections arrive at the different surface parts of the object at all times.

Finally, even the surface of the object facing the fire detector can be evaluated in such a way that the multiplication of the sensor signal 121 with a polynomial winding of the time of mainly third order (d> a, b, c,...) Is integrated in time: surface = ∫ sensor signal (t) * [a + b * t + C * t ² + d * t ³ + ...] dt. Thus, the evaluation unit takes into account by an extra weighting of reflections that arrive late and also the effect that the angle of its surface facing the object with the distance is steeper.

The FIG. 4 shows a further smoke detector 21 according to the invention, which alternately aligned in each case in different directions transmitter 23A, 23B, 23C and sensor 22A, 22B, 22C. There is ever such a transmitter or sensor recorded in all wall sections shown, although not all are shown. Each probe 22A, 22B, 22C is aligned approximately horizontally with three differently spaced regions 24CA, 24CB, 24CC of overlap each with a narrow emitter 23A, 23B, 23C. Each sensor can receive light from three transmitters. They are close to smoke and are sensitive to objects up to several meters away. Thanks to these alignments, a rough detection of the distance from objects to the fire detector without transit time measurement of the radiation is possible. For this purpose, the transmitters 23A, 23B, 23C are operated alternately, and the combination of the actuated transmitter 23A, 23B, 23C and the signal-loaded probe 22A, 22B, 22C reveals the overlapping region of their orientations originating from the reflections.

Claims (7)

1. Fire alarm (1, 11, 21) responding to smoke, a combustion gas or a heating of air, having a detector (2, 12, 22A, 22B, 22C) sensitive to objects in the vicinity of the fire alarm (1, 11, 21),
   characterised in that
   in the conventionally aligned fire alarm (1, 11, 21) the detector (2, 12, 22A, 22B, 22C) is sensitive to objects at the side of the fire alarm (1, 11, 21) within any sector of a circle of 150° about the vertical.
2. Fire alarm according to claim 1,
   wherein the detector (2, 12, 22A, 22B, 22C) is more sensitive to objects at the side of the fire alarm (1, 11, 21) at at least one height than below it at the same distance from the fire alarm (1, 11, 21).
3. Fire alarm according to one of the preceding claims,
   wherein the detector (2, 12, 22A, 22B, 22C) is sensitive to objects above the angle of depression of 20°, measured from the horizontal plane.
4. Fire alarm according to one of the preceding claims,
   wherein the detector (2, 12, 22A, 22B, 22C) is sensitive to objects at the height of the fire alarm (1, 11, 21).
5. Fire alarm according to one of the preceding claims,
   wherein the fire alarm (1, 11, 21) includes a transmitter (3, 13A, 13B, 23A, 23B, 23C) for transmitting electromagnetic, acoustic or other radiation in the range of sensitivity of the detector (2, 12, 22A, 22B, 22C).
6. Fire alarm according to one of the preceding claims,
   wherein the fire alarm (11) includes deflection means (18) for radiation in the range of sensitivity of the detector (12), and wherein the deflection means (18) is designed to deflect such radiation in a conventionally aligned fire alarm (11) from one location in the fire alarm (11) to objects at the side of the fire alarm (11), or vice versa.
7. Method having a fire alarm (1, 11, 21) responding to smoke, a combustion gas or a heating of air, wherein a detector (2, 12, 22A, 22B, 22C) sensitive to objects in the vicinity of the fire alarm (1, 11, 21) is used,
   characterised in that
   in the conventionally aligned fire alarm (1, 11, 21) the detector (2, 12, 22A, 22B, 22C) monitors objects at the side of the fire alarm (1, 11, 21) within any sector of a circle of 150° about the vertical.

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