EP2270762A2 - Smoke alarm and method for testing whether the smoke openings are contaminated - Google Patents

Abstract

The detector has two passages (6, 7) arranged in a partition (3), where one of the passages (7) connects two chambers (1, 2). A temporarily actuated fan (8) is arranged in the other passage. A total air flow is generatable through the latter passage using the fan, and is divided into a main air flow (H) through smoke through openings (4) and a secondary air flow (N) between the chambers through the passages. A sensor element (9) is provided in a region of the former passage. Strength of the secondary air flow is measurable depending on a throttling degree of the smoke through openings. An independent claim is also included for a method for testing contamination from smoke through openings of a smoke detector.

Description

The invention relates to a smoke detector with a housing which has smoke passage openings and comprises a smoke detector and an alarm signaling device. The invention further relates to a method for checking the contamination of smoke passage openings of a smoke detector with a housing.

Smoke detectors are known in the art and commonly have a smoke detector of e.g. may have an optical detection path, and an alarm signaling device, which are housed in a housing. Such a housing is usually mounted on a ceiling, in order to detect smoke which arises in a fire safely. In this case, such a housing may for example be divided into a cover-side base and a room-side housing cover, both of which can be joined together after mounting the base to the ceiling.

For example, by an optical detection path, for example realized by a light-emitting element and a scattered light sensor, can be reliably detected when smoke enters through the smoke passage openings in the housing in the optical detection path and there leads to a light scattering.

It is intended for such a case to trigger an alarm by means of an alarm signaling device, e.g. acoustic type is what such a smoke alarm of the known type a corresponding acoustic sound generator, e.g. may have a piezoelectric element.

Smoke alarms of this known type can therefore usually include appropriate electronics in addition to the aforementioned devices to measure the scattered light by means of the scattered light sensor and to control the alarm signaling device.

It is also known in the prior art that smoke passage openings can become dirty and thus reliable detection of smoke can no longer be guaranteed. Contamination of the smoke passage opening can be effected for example by dust particles in the air, which deposit over time in the opening cross-section of the smoke passage openings or by insects, such as. Spiders or by other mechanisms. When the opening area has been reduced, the passage of smoke through the smoke passages is restricted, thereby increasing the response time of a polluted smoke detector.

It may also happen that smoke openings of a smoke alarm are deliberately closed by people. Such a case may occur when smoke detectors are used e.g. be covered for renovation work, for example, when painting a ceiling. In such a situation, a smoke alarm device is no longer safe to operate.

It is still or will be required in the future that the perfect function, therefore in particular the continuity of the smoke openings, is to be checked regularly in order to ensure the functionality of a smoke alarm. A duty to review concerns For example, the operators of smoke alarm systems or even the landlords of home ownership, in which smoke detectors are installed.

The methods or smoke detectors known to date in the prior art all have the disadvantage that usually indirect measuring methods are used to check the continuity or the degree of throttling of smoke passage openings.

In this case, acoustic or optical methods are often used to detect the pollution metrologically, with such methods or smoke detectors prove to be unreliable if necessary, especially in methods that rely on acoustic, especially resonance measurement, since the acoustic behavior of a smoke detector not only by the contamination of the openings themselves but also by internal dirt deposits in the housing of the smoke detectors, or by mechanical damage housing can change, but otherwise do not affect the functioning of a smoke detector.

It is the object of the invention to provide a smoke detector and a method for checking the contamination of smoke openings, with which in a safe manner, as well as in a simple manner, the degree of contamination of smoke openings in the housing of a smoke alarm or their throttling degree Smoke passage can be checked. It should also be given the opportunity to make the result of a review accessible, in particular without the need for verification staff must enter the installation of a smoke alarm.

To solve the problem, it is provided according to the invention that a method for checking the contamination of smoke openings a smoke alarm is provided with a housing in which inside the housing with a fan, at least temporarily, a total air flow is generated, which, in particular by a selected air duct, divides into a main air flow passing through the smoke passage openings and a secondary air flow within the housing, wherein the strength of the secondary air flow is measured as a measure of the pollution or the throttle wheel of the smoke passage openings.

In a preferred air duct, it may be provided that the main air flow enters the housing from the outside through the smoke passage openings and exits the housing through at least one outlet opening. In this version, the air duct also corresponds to the actual path of the smoke in a fire.

Alternatively, it can also be provided to guide the main air flow so that it emerges from the smoke passage openings and enters the housing through at least one inlet opening. The features mentioned below in relation to the first type of air guide also apply to the second alternative type of air guide, in which case the at least one "inlet opening" is to be replaced by "outlet opening".

The very essential advantage of the method according to the invention is that actually a size is measured, namely an air flow that is directly influenced by the degree of contamination or throttling degree of the smoke passage openings, but not by possibly other changes that are made to the smoke alarm or with time.

Thus, a total air flow is generated here by the at least temporary energization of a fan, for example with a control device. This total air flow is made up of two variable parts of one Main air flow and a secondary air flow, which are guided as mentioned above, or result from a design-related air flow.

It is such that to maintain the total air flow of the secondary air flow increases when the main air flow decreases, which may occur due to the pollution of the smoke passage openings and the consequent throttling of the air flow in the main air flow. An increasing secondary air flow or the strength of the secondary air flow, ie its flow velocity, can thus directly form a measure of the contamination or throttling of the smoke passage openings. Such a measure can thus be determined and e.g. be stored for future evaluations or messages for the purpose of checking the functionality or safety of the smoke detector.

It can be provided, for example, that the smoke detector reports its pollution, e.g. by a signal (optical / acoustic) or a message to a control center, if the flow in the secondary air flow exceeds a predetermined / predefinable limit.

Such a limit may e.g. be stored in the smoke detector. In one application, the limit value during commissioning of such a smoke alarm device can be determined and stored by determining the strength of the secondary air flow of the new unpolluted smoke alarm device at initial startup and storing it as a limit value for later comparison.

For the essential core idea of the invention, it is provided that the secondary air flow occurs only within the housing, so as to ensure a perfect dependence on the main air flow without further influencing.

In order to obtain a corresponding air flow, which ensures this, it may preferably be provided that this air duct is determined by a partition, by means of the interior of the housing of the smoke alarm is divided into two chambers and a first through hole in the partition, in which Fan is arranged and at least one second passage opening in the partition, which connects as well as the first two chambers.

An inventive smoke alarm, which is suitable for carrying out this method according to the invention, therefore has the features that the interior of the housing is divided by a partition wall into two chambers, the first chamber comprises the smoke passage openings and the second chamber at least one opening (exit or Inlet opening, depending on the direction of air flow in the main air flow), which connects the second chamber with the environment.

In the partition wall, a first passage opening and at least one second passage opening are arranged, which connect the two chambers, respectively. In the first passage opening an at least temporarily actuated / actuated fan is arranged, with which a total air flow through the first passage opening in the partition is generated, which is divided into a main air flow through the smoke passage openings and the opening which connects the second chamber with the environment, and a secondary air flow between the chambers through the first and the at least one second passage opening, wherein a sensor element is provided, with which the strength of the secondary air flow is measurable, which as mentioned above, depends on the degree of contamination of the smoke passage opening.

As mentioned above, two alternative directions of flow for the main air flow can be provided or selected, if necessary. Also by a reversibility of the fan rotation direction, namely preferably from the outside through the smoke passage openings to the first passage opening and from there to the at least one opening in the second chamber to the surroundings, this opening then serving as an outlet opening, or vice versa, this at least one opening then serving as an inlet opening.

It can preferably be provided that the sensor element is arranged in or in the region of the at least one second passage opening.

This arrangement is particularly preferred since, in the region of the at least one second through-opening, a maximum flow velocity is achieved on account of the maximum achieved reduction in cross-section in the through-opening. Therefore, the measurement accuracy proves to be the largest at this point.

In a further preferred embodiment, it can be provided that a smoke alarm device is constructed in two parts, in which case, as a possible embodiment, said second chamber is assigned to a base area, i. an area which is mounted on a ceiling of a room and the first chamber is associated with a cover of the housing, which is thus monited room side. However, other constructions, in particular one-piece housing constructions, are also conceivable here.

In principle, any suitable sensor element can be used to measure the strength of the secondary air flow.

For example, in one embodiment, it is possible to use a rotor in a second passage opening, which is set in rotation by the secondary air flow which occurs through this second passage opening. Thus, by measuring the rotational speed of the rotor, for example, optically by a light barrier or by voltages in a driven by the rotor Generator are induced to measure the strength of the secondary air flow.

It is also possible with a differential pressure sensor to measure the pressure difference between the two chambers. This is also dependent on the flow velocity in the secondary air flow given the geometry of the passage opening.

In another, further preferred embodiment, it can also be provided that the sensor element is set up to measure the temperature profile of a heated and cooling in the secondary air flow means. From the measured with the sensor element temperature profile can then be determined a measure of the strength of the secondary air flow and thus the pollution or throttling of the smoke passage openings. As a means to be heated or heated, for example, the sensor element itself, the flowing secondary air or a separate element can be used.

In one embodiment, a sensor element may e.g. be designed as a temperature-dependent resistor, for example as a resistor with a negative temperature coefficient (NTC). Such or other non-moving sensor elements have the particular advantage that friction does not have to be overcome, as for example in the case of the rotor initially mentioned, in order to initially set it in motion. Accordingly, such a rotor will only sufficiently detect flow velocity above a certain minimum level, since it will only be set into rotation from standstill from such a minimum thickness.

In contrast, the preferred sensor element, which is designed for example as a temperature-dependent resistor, regardless of any friction effects to be overcome, so that even the lowest flow velocities can be measured safely.

In order to measure the magnitude of the secondary air flow by measuring the cooling behavior of a heated medium, a heating device may be used which is provided in the housing, e.g. is arranged in one of the two chambers or in a passage opening. Such a heating element may be arranged separately, in particular adjacent to the sensor element, e.g. if it is intended to heat the sensor element itself or the flowing secondary air. In one embodiment, the sensor element itself may also constitute the heating device, e.g. as a temporary energized temperature-dependent resistance. Such a resistor will heat up by current supply up to a certain temperature and can then be cooled by the secondary air flow.

In all these embodiments, it is therefore possible to measure the resistance value of this temperature-dependent resistance as a function of time and from the so measured course of the resistance value information about the cooling behavior and thus on the strength of the secondary air flow and thus simultaneously on the pollution of the smoke passage openings to obtain.

In order to realize this, a corresponding control and / or measuring device can be provided within the smoke alarm, with which the heating of the used agent takes place, e.g. the heating of a separate heating device or the energization of the sensor element takes place and / or the subsequent measurement of the cooling behavior, in particular measurement of the resistance value with time.

It may be provided in a possible embodiment that not immediately after the end of a heating with the measurement of the cooling behavior or at least not with the evaluation of the measured values is started, but that first the measuring device waits for a certain time, since after heating of the sensor element , in particular the Temperature-dependent resistance initially a cooling this dominated by radiation over the cooling behavior due to convection, which is due to the secondary air flow.

It is therefore advantageously provided to set up the measuring device such that it waits for the time in which the cooling behavior is dominated by this heat radiation.

In yet another embodiment, it may be provided, before performing a measurement, as described above, the fan first for a predetermined / predeterminable time to a thermal and / or hydrothermal balance in the smoke detector without heating so before the actual measurement phase receive. It may then in an alternative the measuring process, i. the heating takes place immediately when the fan is running or in a contrast preferred variant only after the fan for a turn predetermined / predetermined time was stopped. The heating therefore takes place when the fan is at standstill, after which, after the heating up, the fan is then started again for a predetermined / predefinable measuring time, e.g. until a certain limit (temperature or resistance) has been reached in the course of the temperature.

Regardless of these embodiments, a heating can take place even when the fan is running.

To ensure that the formation of a measurable secondary air flow are not opposed to large internal resistances, it may be provided in a further preferred structural embodiment of the smoke alarm, instead of only a single second passage opening to provide at least two second through holes, wherein the sensor element for determining the Strength of the secondary air flow in one of the at least two passage openings is arranged. Thus, although the passage in the cross section is reduced by the arrangement of the sensor element, for example, the resistance in one of the two through holes, but due to the at least one further through hole enough further cross section remains to achieve a significant secondary air flow.

According to the invention it can be provided in a further embodiment, to use a control device in the smoke detector, which is adapted to energize the fan for checking the contamination of the smoke passage openings at least temporarily. This can be done periodically, in particular automatically, e.g. by an internal program within the smoke detector.

In another embodiment, it is also possible to carry out the test for fouling of the smoke passage, i. to carry out an energization of the fan and evaluation of the result of the sensor element triggered, e.g. through an external request. Such an external request may be given, for example, by maintenance personnel located in the vicinity of the smoke alarm device, or may also be given at a distance from it remotely, e.g. by a request that is communicated by radio to the smoke detector, for which this may have a corresponding radio receiving device.

It can also be provided that a smoke detector comprises a communication device, for example, which also allows the reception of the aforementioned requirement, by means of the result of the measurement of the strength of the secondary air flow and thus a measure of the pollution of the smoke passage openings to an external receiving unit is, for example, a management system. Such Message can be wired, but more preferably wirelessly via wireless.

It is also possible at any time for responsible personnel, for example, the landlord of residential property to make a review of smoke alarms without these people must enter the object in which one or more smoke detectors are mounted.

A further advantageous embodiment of the smoke alarm device and the method according to the invention is seen therein, when the present in the housing of the smoke alarm fan is also used in addition to its purpose of checking the contamination to at least temporarily suck ambient air into the housing, e.g. To avoid false alarms or to improve the response, in particular to shorten the response time.

Accordingly, a control device may be configured to cause this suction when detection takes place in the detection path. In this case, before an external alarm triggering this sucking done to check whether it is only a short-term detection, e.g. with cigarette smoke or an insect or dust / aerosol etc. or whether smoke still follows.

With such a detection or initially internal alarm triggering and subsequent energization of the fan, ambient air is then actively drawn into the smoke alarm device. In the case of an insect or a merely limited cloud of, for example, cigarette smoke, dust, etc., the smoke detector will detect with its detector, eg optical detection path that no smoke due to a source of fire is present.

It may then be provided to refrain from an alarm triggering, in particular external alarm triggering and switch off the fan again after the detection by the smoke detector. Only in the event that the smoke detector continues to detect smoke, even with fan operation and active intake of ambient air, can it then be provided to also trigger an external alarm, e.g. by an acoustic signal and / or communication to a danger control panel ..

In order to achieve an effective total air flow and a favorable division into main and secondary air flow in a smoke detector, it may further be provided that the first passage opening in which the fan is arranged is given by the inner free cross section of a cylindrical pipe section, which in the partition is arranged and receives the fan.

Furthermore, provision may be made for the first through-opening and the at least one second through-opening to be spaced in the direction of the diameter of the dividing wall, in particular for smoke detectors, which are usually circular in cross-section. In this way, a maximum decency between the two passage openings can be achieved, which ensures that a clear division of the total air flow in the main and secondary air flow is effected.

In a further embodiment, it may be provided to use the fan to blow the smoke passage openings of dirt. In this case, a direction of rotation of the fan is preferably selected, which causes the main air flow from the interior of the housing through the smoke passage openings leads to the outside, so that dirt is carried out of the smoke alarm. It may be provided to operate the fan faster rotating than is the case with a measurement of pollution.

It may also be provided to make the direction of rotation of the fan reversible, e.g. by appropriate control by the control device. In this case, a measurement of contamination in one direction of rotation and a cleaning in the other direction of rotation can be done. It is also possible to carry out the measurement of contamination or the throttling of the smoke passage opening in both directions of rotation.

An embodiment of the invention is shown in the following figure.

The FIG. 1 shows a schematic representation of a housing G of a smoke detector, in which the simplification of the inventive principle, a smoke detector and an alarm device, in particular as an optical detection path with light emitter and scattered light receiver, and for example an acoustic tone generator are not shown.

The FIG. 1 shows that it is provided according to the invention, the total internal volume of the housing G to divide into two chambers, namely with respect to the FIG. 1 , in an upper chamber 1 and a lower chamber 2. In this case, the lower chamber 2 may be assigned to a mounting base of the smoke alarm, so that in the actual mounting situation of the smoke alarm on a room ceiling, the chamber 2 is arranged on the ceiling side.

It is provided here that two passage openings are provided in the partition 3, which here causes the separation between the two chambers 1 and 2, namely here a particular left-side passage opening 6 in which a fan 8 is arranged, and a particular right-side passage opening. 7 in or in the vicinity of which a sensor element 9 is arranged. Of course, the left or Right-side orientation of the through hole for the principle of the invention irrelevant.

If now the fan 8 is energized, which is e.g. can be done by a provided in the smoke detector control device, so a total air flow is generated which takes place in this embodiment of the chamber 1 into the chamber 2 through the passage opening 6 therethrough. In this case, this total air stream is divided into a main air flow H and a secondary air flow N.

The main air flow H is formed by ambient air L, which is sucked through the smoke passage openings 4 in the chamber 1. By the fan 8, this ambient air is conveyed as a part of the total air flow through the passage opening 6 and occurs due to the pressure increase caused thereby in the chamber 2 through the opening 5, which acts here as the outlet opening 5 in this chamber 2 in turn in the direction of the environment. In reverse rotation of the fan 8, the Strömunsrichtung is also reversed and the opening 5 would act as an inlet opening. All following explanations apply analogously to this alternative flow direction.

At the same time in addition to this external main air flow, an internal secondary air flow is effected, in which air is conveyed within the two chambers 1 and 2 as a side stream N shown here in a circle, said circle between the two chambers 1 and 2 both through the passage opening 6, in which the fan is arranged, as well as through the passage opening 7 is closed. For the definition of main and secondary air flow, it is irrelevant in all possible embodiments that in practice the air mixes the main and secondary air flow and separates again.

To maintain the total air flow, which is essentially determined by the speed of rotation of the fan and the internal

Results in flow resistances, it is caused that when reducing the main air flow, e.g. by a cross-sectional reduction or blockage of the smoke passage openings 4, the flow rate in the secondary air stream N increases.

A measure of the degree of soiling or throttling of the main air flow is accordingly the flow velocity in the secondary air flow N, which, as shown here, can be measured by a sensor element 9, which is located in or in the vicinity of the second through-opening 7. For example, as described in the general section, it may be a temperature dependent resistor whose cooling behavior, i. whose resistance change can be measured with time after heating by energizing.

The so measured measure of the flow rate, which is a measure of the pollution of the smoke passage openings 4, can be stored for example in all possible embodiments of the invention within a Rauchwarnmeiders and / or external to e.g. be communicated by radio in order to document a check of the Rauchwarnmeiders on function and continuity of the flue gas inlet openings.

There, like that FIG. 1 shows, with the fan not only an internal circulation and thus a secondary air flow N is generated, but in particular causes ambient air L is sucked through the flue gas inlet openings 4 into the chamber 1 and thus into the interior of the housing G, the invention can also be used to shorten response times or to exclude false alarms, by a temporary detection of foreign bodies within the example optically designed detection path.

By actively sucking in ambient air can be checked whether following detection of particles, such as smoke particles in the detection section, followed by the air sucked in more particles and thus certainly detected a fire or denied.

Claims (23)

Smoke alarm with a housing, which has smoke passage openings (4) and a smoke detector and an alarm signaling device, characterized in that a. the interior of the housing is divided by a partition wall (3) into two chambers (1, 2), b. the first chamber (1) comprises the smoke passage openings (4) and the second chamber (2) comprises at least one opening (5) which connects the second chamber to the surroundings, c. a first passage opening (6) and at least one second passage opening (7) are arranged in the dividing wall (3), connecting the two chambers (1, 2) in each case, d. in the first passage opening (6) an at least temporarily operable fan (8) is arranged, e. with the fan (8) a total air flow through the first passage opening (6) can be generated, which is divided into a main air flow (H) through the smoke passage openings (4), through the first passage opening (6) and the at least one opening (5) in the second chamber, and a secondary air flow (N) between the chambers (1,2) through the first and the at least one second passage opening (6,7), f. a sensor element (9) is provided, in particular in or in the region of the at least one second passage opening (7), with which the strength of the secondary air flow (N) can be measured, which depends on the degree of throttling of the smoke passage openings (4). Smoke alarm device according to claim 1, characterized in that the sensor element (9) is designed for measuring the flow velocity and / or for measuring the differential pressure. Smoke alarm device according to claim 2, characterized in that the sensor element is adapted to measure the temperature profile of a heated and cooling in the secondary air flow means, in particular wherein this means is formed by the sensor itself, the flowing secondary air or a separate element. Smoke alarm device according to claim 2 or 3, characterized in that the sensor element is designed as a temperature-dependent resistor, in particular with a negative temperature coefficient or as an air-flow-actuated rotor. Smoke alarm device according to one of the preceding claims, characterized in that the sensor element for measuring a flow velocity by means of a current flow through the sensor element is heated or a device for heating the air flow or for heating the sensor is provided, wherein by the sensor element from the measured temperature profile the cooling a measured variable correlated with the flow velocity can be provided. Smoke alarm device according to one of the preceding claims, characterized in that the measuring device is adapted to wait after heating before the measurement of the cooling behavior, a time in which the cooling behavior is dominated by heat radiation. Smoke alarm device according to one of the preceding claims, characterized in that the measuring device is set up after switching on the fan and before heating before the measurement the cooling behavior to wait for a time in which a uniform Durchtemperierung the Rauchwarnmeiders. Smoke alarm device according to claim 7, characterized in that the measuring device is arranged to stop the heater before heating and start again after the heating. Smoke alarm device according to one of the preceding claims, characterized in that at least two second passage openings (7) are provided and the sensor element (9) is arranged in one of the at least two second passage openings. Smoke alarm device according to one of the preceding claims, characterized in that a control device is provided which is adapted to energize the fan (8) for checking the contamination of the smoke passage openings (4), in particular automatically temporarily or triggered by an external request. Smoke alarm device according to claim 10, characterized in that the control device is further configured, at least temporarily to energize the fan (8) to avoid false alarms and so actively suck in ambient air in the smoke alarm. Smoke alarm device according to one of the preceding claims, characterized in that it comprises a communication device by means of which the result of the measurement of the strength of the secondary air flow (N) to an external receiving unit, in particular a management system is signaled, in particular wirelessly by radio. Smoke alarm device according to one of the preceding claims, characterized in that the evaluation of the result of the measurement of the secondary air flow (N) takes place within the device and a message can be output by the device in case of need. Smoke alarm device according to one of the preceding claims, characterized in that the first passage opening (6) is given by the inner free cross section of a cylindrical pipe section which is arranged in the partition wall (3) and receives the fan (8) inside. Smoke alarm device according to one of the preceding claims, characterized in that the first through-opening (6) and the at least one second through-opening (7) in the direction of the diameter of the partition wall (3) are spaced. Method for checking the contamination of smoke passage openings (4) of a smoke detector with a housing, characterized in that inside the housing with a fan (8) at least temporarily, a total air flow is generated, which, in particular divided by a selected air flow into a main air flow ( H) passing through the smoke passage openings and a secondary air flow (N) within the housing, the magnitude of the secondary air flow (N) being measured as a measure of the restriction produced by the smoke passage openings. A method according to claim 16, characterized in that the main air flow from the outside through the smoke passage openings (4) enters the housing and through at least one outlet opening (5) emerges from the housing. A method according to claim 17, characterized in that the air guide is determined by a partition (3), by means of which the interior of the housing is divided into two chambers (1,2) and a first passage opening (6) in the partition in which the Fan is arranged and at least one second passage opening (7) in the partition (3), which connects the two chambers (1,2) as well as the first (6). Method according to one of the preceding claims 17 or 18, characterized in that the strength of the secondary air flow (N) is measured by measuring the cooling behavior of the heated air in the smoke detector and / or a heated element used for measurement, in particular of the sensor itself. Method according to one of the preceding claims 16 to 19, characterized in that the strength of the secondary air flow (N) is measured by measuring the rotational speed of an actuated by the secondary air flow rotor or by measuring the differential pressure between the chambers (1,2). Method according to one of the preceding claims 16 to 20, characterized in that the fan is also used in addition to its purpose of checking the contamination to at least temporarily suck ambient air into the housing to improve the response or to avoid false alarms. Method according to one of the preceding claims 16 to 21, characterized in that a reversal of the direction of rotation of the fan is generated, in particular to blow air through the smoke passage openings to the outside and to free the smoke inlet openings of contamination. Method according to one of the preceding claims 16 to 22, characterized in that the fan, in particular after a reversal of rotation, for faster removal of contaminants from the smoke passage openings is operated faster than when performing the measurement.

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