NO344015B1

NO344015B1 - A temperature-triggered alarm arrangement

Info

Publication number: NO344015B1
Application number: NO20180236A
Authority: NO
Inventors: Jan Christer Svaasand; Morten Lorentzen
Original assignee: Safetemp As
Priority date: 2018-02-14
Filing date: 2018-02-14
Publication date: 2019-08-19
Also published as: WO2019158647A1

Description

A TEMPERATURE-TRIGGERED ALARM ARRANGEMENT

Technical Field

[0001] The present invention relates to a versatile temperature alarm arrangement that is provided with an attachment means and an audible alarm generator.

Background Art

[0002] A vast variety of different temperature sensors or temperature alarms exist. In addition, smoke detectors are well known and commonly used public buildings, factories, and in private residences.

[0003] The overall purpose of such devices is to save lives, as well as material values. A drawback of many of these devices is that they respond, i.e. produce an alarm, as a consequence of a fire that has already started. A typical example of such devices are smoke detectors that are usually arranged in the ceiling inside buildings. When these devices produce an alarm, it often is because a fire has already started. In such cases, it may be too late to put out the fire, and sometimes it is even to late to exit the building without harm.

[0004] Notably, common features of these types of alarms is that they are relatively few and are configured to respond to fire outbreaks that take place at a significant distance from the alarms. For instance, before a smoke alarm reacts, a fire outbreak must first produce smoke, and then the smoke must find its way to the position of the smoke sensor. Likewise, for alarms reacting on temperatures, a fire outbreak must progress for a significant period before being able to heat the air / gas at the location of the temperature alarm.

[0005] Some modern electric devices have built-in temperature sensors, and are configured to cut off the electric power if excessive temperatures are measured. Older electric devices are however typically not equipped with such means. Even many modern devices, such as tablet computers and smartphones, or electrically operated toys or tools, lack such temperature monitoring means.

[0006] Furthermore, there exist small temperature sensors that are linked to an alarm central through wired or wireless connection. For instance, there is suggested to use small IOT (Internet of Things) chips that can be mounted to various items, to monitor various parameters such as temperature. Such chips will typically communicate through a wireless link to a remotely arranged control unit.

[0007] Publication JP2014182665 discloses an alarm unit that is triggered by temperature. It is provided with a housing, a battery, and a warning unit. A control unit communicates with a temperature sensor and with the alarm unit. The alarm unit according to this publication has the warning unit arranged outside the housing.

[0008] US4065758 describes an alarm detector which is responsive to rate of change of a monitored condition, such as temperature.

[0009] WO2008102865 further shows an alarm device with a housing, a detector, a printed circuit assembly and a speaker. The main components of this device is arranged inside the housing.

[0010] An object of the present invention may consequently be to provide an alarm arrangement that produces an audible alarm before a fire starts.

[0011] Another object of the invention may be to provide a fire-preventive alarm arrangement that is easy to use and/or which is cheap.

[0012] Yet an object of the present invention may be to provide an arrangement that produces an audible alarm if the temperature of a surface exceeds a given threshold.

[0013] A further object of the invention may be to provide an alarm arrangement that is easily attachable to a large variety of different equipment.

Summary of invention

[0014] According to the present invention, there is provided a temperature triggered alarm arrangement comprising a temperature sensor, a housing, a battery holder, an audible alarm generator, an attachment means and a control unit. The control unit is in communication with the temperature sensor and with the audible alarm generator. The control unit is configured to trigger the audible alarm generator when a temperature measured by the temperature sensor is above a predetermined threshold value. The predetermined threshold value is below 80 °C. The attachment means may comprise an adhesive layer having a layer aperture through the adhesive layer. The arrangement further comprises a circuit board that comprises the temperature sensor on a first side of circuit board. The circuit board further comprises a thermal convection channel that extends through the circuit board at the position of the temperature sensor. The thermal convection channel provides for heat transfer through the circuit board, from the second side of the circuit board to the opposite first side of the circuit board.

[0015] With such an alarm arrangement, the alarm will be triggered before a temperature that is representative of a fire outbreak is reached. A person hearing the alarm will then be put in condition to remove the cause of a possible fire outbreak before the outbreak occurs. Furthermore, malfunctioning products, typically electric products such as battery chargers, electric sockets, or electric appliances can be discovered and be disposed of.

[0016] Notably, while the current trend in this field is to produce increasingly more advanced and complex devices, the present invention moves in a contrary direction by providing an easy-to-use alarm arrangement that needs no further equipment or software installation by the end user.

[0017] According to some embodiments of the present invention, the predetermined threshold value can be below 70 °C, or even below 60 °C.

[0018] With such an arrangement one obtains that heat convection takes place through an air volume that is not exposed to air current / draught. An air current or draught could reduce the convection efficiency, since heated air could be transported away and be replaced with fresh, cold air. Thus, with an adhesive layer with a layer aperture, one obtains a protected or covered heat convection path from the surface that shall be monitored, and into the alarm arrangement. Advantageously, in preferred embodiments the layer aperture can be fully encircled by the adhesive layer.

[0019] In this manner, one can arrange the temperature sensor in a protected environment, such as in the space between the inner side of the housing and the first side of the circuit board, while still provide efficient heat transfer to the temperature sensor. In the non-limiting, detailed example description below, this space is referred to as the upper space.

[0020] In some embodiments, the thermal convection channel through the circuit board may be a metal element that extends through the circuit board. In other embodiments, the thermal convection channel may be a through hole, or an aperture, that extends through the circuit board. Such an aperture will be filled with air (and hence a gas).

[0021] According to an embodiment of the present invention, the housing can define a main space inside it, wherein the alarm arrangement further has a circuit board that abuts against an inner surface of the housing. In such way, the circuit board can divide the main space into a lower space, in which the battery holder is arranged, and an upper space, which is located between the circuit board and an upper face of the housing.

[0022] Advantageously, by having the battery holder made of metal, one obtains an efficient heat transfer from the surface that is monitored, towards the position of the sensor.

[0023] The control unit can be configured to trigger the audible alarm generator when a temperature increase rate, as measured by the temperature sensor, is above a predetermined rate threshold.

[0024] According to such embodiments, the control unit can be configured to monitor not only the current measured temperature, but also to monitor an increase rate of the measured temperature. For instance, even if the measured temperature is below the said predetermined threshold value, the control unit may then still trigger the audible alarm generator if the temperature is rising too fast. If for instance, merely as an example, the measured temperature rises at a rate of more than 5 °C per minute, then the control unit may be configured to trigger the audible alarm generator. One may further program the control unit to perform such monitoring of temperature increase rates only at temperatures above a predetermined lower threshold value. For instance, the control unit may be configured to perform such rate monitoring at temperatures above 40 °C.

[0025] Advantageously, the alarm arrangement according to the invention, and possibly in combination with any other embodiment or feature discussed herein, may be self-contained. In such embodiments, the electric power supply in the form of a battery, and the communication between the control unit and the temperature sensor, and the communication between the control unit and the audible alarm generator, are arranged within the housing.

[0026] With the term “self-contained” is herein meant that the alarm arrangement is configured to operate fully on its own, i.e. without needing to be connected to any other component, such as a control unit, an external electric power source, or external temperature sensor.

[0027] The battery holder can be configured to receive a button cell battery having a flat and circular shape and having a battery diameter, wherein the thermal convection channel in the circuit board and the layer aperture in the adhesive layer both are arranged within the perimeter of the battery diameter.

[0028] With such embodiments, one obtains to guide a possible heat from the monitored surface into the battery from the position of the layer aperture of the adhesive layer, and to further transmit heat from the thus heated battery towards the temperature sensor through the thermal convection channel. In this manner, one exploits the heat transfer capacity of the battery.

[0029] The battery holder can be configured to receive a button cell battery having a substantially flat and circular shape with a battery diameter. In such embodiments, the alarm arrangement can further comprise a circuit board that has a circular shape, with a circuit board diameter which is less than 1.5 times larger than the battery diameter.

[0030] It will be appreciated that several of the features disclosed herein contributes in making an alarm arrangement that may have a relatively small size. By obtaining a small size, the arrangement will be easier to use in various types of equipment. In preferred embodiments, the alarm arrangement may extend a small distance up from the surface that it monitors. Furthermore, it may cover only a small area of the said monitored surface.

Brief description of drawings

[0031] While some of the general features of the present invention have been discussed above, some more detailed examples of embodiment will be given in the following with reference to the drawings, in which

Fig. 1 is a perspective view of temperature triggered alarm arrangement according to the present invention;

Fig. 2 is a perspective view illustrating a typical use of the alarm arrangement according to the invention;

Fig. 3 is an exploded perspective view of three main parts of the alarm arrangement; Fig. 4 is a schematic top view of a circuit board being part of the alarm arrangement; Fig. 5 is a side view of the alarm arrangement, shown without the housing;

Fig. 6 is an enlarged side view with the circuit board shown with a cross section view; Fig. 7 is a principle perspective view of an adhesive layer configured for attachment of the alarm arrangement to a surface that shall be monitored;

Fig. 8a is a cross section side view through the alarm arrangement, when attached to a surface;

Fig. 8b is a cross section view corresponding to Fig.8a, seen with an angle orthogonal with respect to Fig.8a;

Fig. 9 is an alternative embodiment of the alarm arrangement, having another type of attachment means;

Fig. 10 is a perspective view illustrating a possible use of the embodiment shown in Fig. 9; and

Fig. 11 is a perspective view showing an alternative embodiment of the housing of an alarm arrangement according to the invention.

Detailed description of the invention

[0032] Fig. 1 shows a perspective view of an embodiment of an alarm arrangement 1 according to the present invention. It has a circular, cylindrical side wall 3 and a flat upper face 5.

[0033] Fig. 2 shows a piece of electric equipment 10, here in the form of a multi-plug extension cord, where an alarm arrangement 1 according to the invention is attached to the main body of the electric equipment 10. The alarm arrangement 1 monitors the temperature on the outer surface 100 of the electric equipment 10, and triggers an audible alarm if the monitored temperature exceeds a given threshold value.

Consequently, if the multi-plug extension cord should malfunction and thus should overheat, the alarm arrangement 1 will give an audible alarm. In the shown embodiment, the alarm arrangement 1 can advantageously be attached to the extension cord by means of an adhesive layer. This will be discussed further below.

[0034] Fig. 3 is a perspective exploded view showing three main parts of the temperature triggered alarm arrangement 1. The arrangement has a housing 7, which in this embodiment dictates the general shape of the alarm arrangement 1. Furthermore, it has a circuit board part 9, which is configured to fit entirely inside the perimeter of the housing 7. It also has a battery 11.

[0035] The circuit board part 9 comprises a battery holder 13, which will be discussed further below. The circuit board part 9 is thus configured to receive the battery 11, which consequently also will fit into the housing 7. The circuit board part 9 further has a circuit board 15, comprising various components that will be discussed below. In the discussed embodiment, the battery holder 13 is fixed to the circuit board 15, typically by soldering, a glue, or by other means.

[0036] In the shown embodiment, the battery 11 is a button cell battery, which has substantially the shape of a coin. I.e. it has a flat upper surface and a parallel flat lower surface, and a circular side wall extending between the two flat surfaces. The battery 11 has a battery diameter 11a that constitutes an outer perimeter of the battery.

[0037] Fig. 4 is a top view if the circuit board 15, the upper side of which is provided with various electric components. A control unit, here in the form of a microcontroller 19, is arranged on the circuit board. The microcontroller 19 comprises a temperature sensor 20 and is powered with the battery 11. Also shown in Fig.4 is an audible alarm generator 21, which is configured to produce an audible alarm when triggered by the control unit 19.

[0038] In the circuit board 15 there is provided a thermal convection channel 23, which is barely visible in Fig.4. In the shown embodiment, the thermal convection channel 23 is a through hole extending through the circuit board 15. The function of the thermal convection channel 23 is to transmit heat to the temperature sensor 20, which in the shown embodiment is embedded in the control unit 19.

[0039] Fig. 5 is a side view illustrating the circuit board part 9 and the battery 11 in a situation where the battery 11 is received by the battery holder 13. The battery holder 13 can be in the form of a metal clip, configured to hold the battery 11 with a clamping grip. The battery holder 13 can thus have a lower projecting part 13a, and an intermediate part 13b that connects the lower projecting part 13a to the circuit board 15. In such embodiments, the battery holder 13 constitutes a clip together with the circuit board 15.

[0040] By using a battery holder 13 that is produced of metal, one obtains good thermal conductivity. This is advantageous as one wants to conduct heat from the surface that is being monitored, towards the temperature sensor 20.

[0041] The lower projecting part 13a will contact a first battery electrode of the battery 11, while a portion of the circuit board 15 will contact the second battery electrode. Typically, the battery holder 13 will contact the “+” electrode, while the circuit board 15 will contact the “–“electrode.

[0042] Fig. 6 is an enlarged side view of a portion of the circuit board part 9 and the battery 11, showing the circuit board in a cross-section view. In this view, the thermal convection channel 23 is shown. In this embodiment, the thermal convection channel 23 extends as an air-filled aperture, through the circuit board 15 at the position of the temperature sensor 20. As discussed above, in this embodiment the temperature sensor 20 is embedded in the control unit 19. The thermal convection channel 23 is thus configured to convey heat through the circuit board 15, so that the temperature sensor 20 is heated.

[0043] In other embodiments, the thermal convection channel 23 may be formed with a metal component extending through the circuit board 15. Such a metal component will efficiently transmit heat towards the temperature sensor 20.

[0044] Reference is now given to Fig.7, Fig.8a and Fig.8b. Fig. 7 is a principle view of an attachment means 25. In this embodiment, the attachment means is in form of an adhesive layer 25 which is used to attach the alarm device 1 to a surface that shall be monitored. The adhesive layer 25 will thus be arranged between the battery holder 13, and the surface that shall be monitored.

[0045] The adhesive layer 25 can typically be in the form of a double-sided tape, i.e. a layer having an adhesive coat on both sides.

[0046] In the shown embodiment, the adhesive layer 25 is provided with a layer aperture 25a, which extends through the adhesive layer 25. The layer aperture 25a allows heat from the surface that shall be monitored to be transported into the alarm arrangement 1.

[0047] Fig. 8a and Fig.8b schematically depict a surface 100 of a piece of electric equipment 10 that shall be monitored. The surface 100 can typically be the surface of a battery charger or other electric appliance.

[0048] As can be seen in Fig.8a and Fig.8b and as illustrated with the inserted arrows, heat from the surface 100 is conveyed through the layer aperture 25a, and into the battery 11. The lower projecting part 13a of the battery holder 13 may be perforated or otherwise not fully covering the layer aperture 25a, or it may be totally covering the layer aperture 25a. Either way, heat will be transported beyond the lower projecting part 13a and into the battery 11.

[0049] From the battery 11, the heat is further conveyed past the lower projecting part 13a of the battery holder 13, and into the thermal convection channel 23, shown in Fig.8a. As the air / gas in the thermal convection channel 23 is heated, the control unit 19, and thus the temperature sensor 20, will be heated.

[0050] Advantageously, the layer aperture 25a in the adhesive layer 25 is fully surrounded by the adhesive layer. In this way, wind or draught in the ambience will not remove heated air from the surface 100.

[0051] The same applies with preferred embodiments of the circuit board 15. By having the thermal convection channel 23 in the form of an air-filled aperture, fully encircled by the circuit board 15, a good thermal conductivity is obtained from the battery 11 to the sensor 20 (control unit 19).

[0052] It should be noted that although the embodiment discussed with reference to the shown drawings have the temperature sensor 20 embedded in the control unit 19, other embodiments may comprise a temperature sensor that is separate from the control unit. In such embodiments, the temperature sensor 20 and the control unit 19 will of course be connected, so that signals from the temperature sensor is received by the control unit.

[0053] Notably, according to the embodiment depicted in Fig.8a and Fig.8b, both the layer aperture 25a and the thermal convection channel 23 are arranged within the perimeter of the battery diameter of the battery 11. In this manner, one can exploit the heat transfer capability of the battery to transfer heat from the monitored surface 100 towards the temperature sensor 20.

[0054] Still referring to Fig.8a and Fig.8b, the housing 7 surrounds a main space 8a inside it, within which the circuit board 15 and the battery holder 13 is located. The circuit board 15 divides the main space 8a into a lower space 8b and an upper space 8c. The battery holder 13 is arranged in the lower space 8b. In the shown embodiment, the temperature sensor 20 is arranged in the upper space 8c.

[0055] To position the circuit board 15 correctly inside the housing 7, and to effectively divide the lower space 8b from the upper space 8c, the housing 7 comprises a shoulder 7a arranged on the inner wall of the cylindrical side wall 3 of the housing. The peripheral edge of the circuit board 15 is configured to abut against the shoulder 7a, and thereby provide a certain sealing effect to prevent air from flowing freely between the lower space 8b and the upper space 8c.

[0056] Consequently, if the surface 100 becomes warm, the heat transferred from it into the housing 7, need not heat the entire main space 8a inside the housing.

Rather, only the lower space 8b will be heated. In this manner, the heat will be transmitted towards the temperature sensor 20 relatively fast.

[0057] In addition, by separating the main space 8a into the lower space 8b and the upper space 8c, one obtains some heat isolation from the surroundings, since a cold upper face 5 will not contribute in cooling the air inside the lower space 8b.

[0058] The skilled reader will appreciate that the terms “upper space” and “lower space” are used for convenience, and does not relate to the direction of gravity, but rather to the surface 100 to which the alarm arrangement is configured to be attached.

[0059] Advantageously, the peripheral edge of the circuit board 15 can be made to fit snugly, with some friction, into the cylindrical side wall 3 of the housing 7. In this manner one needs no further means for connecting the housing 7 to the circuit board 15. Thus, to replace the battery 11, one can simply grip the battery holder 13 and pull the circuit board part 9 (cf. Fig.3) out of the housing 7.

[0060] The housing 7 may be produced in any suitable material, such as metal or plastic. By using plastic, it is expected that one will obtain a better thermal isolation of the main space 8a from the surroundings.

[0061] Fig. 9 and Fig.10 illustrate an alternative embodiment of the present invention. In this embodiment, the attachment means of the alarm arrangement 1 is in form of an attachment clip 125.

[0062] As shown in Fig.10, the attachment clip 125 is particularly suitable for connection to a power cord.

[0063] Other embodiments may involve other types of attachment means, such as glue or a magnet.

[0064] Fig. 11 depicts an alternative embodiment of the housing 107 of a temperature triggered alarm arrangement according to the invention. In this shown embodiment, the housing 107 is provided with a battery insertion opening 108, through which the battery 11 can be inserted into the housing and into the battery holder.

[0065] Also shown in Fig.11 is a battery removal opening 110 in the housing 107. The battery removal opening 110 is arranged in the cylindrical side wall 103 of the housing 107. To remove a battery from the alarm arrangement, the user can push the battery out through the battery insertion opening 108 by applying a force onto the battery by inserting an object through the battery removal opening 110. Such an object may be any suitable type of sufficiently thin and elongated object, such as the battery removal tool 200, which is also shown in Fig.11. As will be appreciated, any suitable object can be used to remove the battery, such as a toothpick.

[0066] According to preferred embodiments of the present invention, the control unit 19 is configured to trigger the audible alarm 21 when the measured temperature exceeds 50°, 70° or 80° C. Notably, the alarm arrangement 1 may thus trigger the audible alarm before a surface temperature that is comparable to the temperature of a fire is reached.

Claims

1. A temperature triggered alarm arrangement (1) comprising a temperature sensor (20), a housing (7), a battery holder (13), an audible alarm generator (21), an attachment means (25), and a control unit (19) in communication with the temperature sensor (20) and the audible alarm generator (21), wherein the control unit (19) is configured to trigger the audible alarm generator (21) when a temperature measured by the temperature sensor (20) is above a predetermined threshold value, wherein the predetermined threshold value is below 80 °C, wherein the attachment means (25) comprises an adhesive layer having a layer aperture (25a) through the adhesive layer, characterized in that it further comprises a circuit board (15) that comprises the temperature sensor (20) on a first side of circuit board (15), and that the circuit board (15) further comprises a thermal convection channel (23) that extends through the circuit board (15) at the position of the temperature sensor (20), from a second side of the circuit board to the opposite first side of the circuit board.

2. A temperature triggered alarm arrangement (1) according to claim 1, characterized in that the thermal convection channel (23) comprises an aperture through the circuit board (15), which is filled with gas.

3. A temperature triggered alarm arrangement (1) according to any one of the preceding claims, characterized in that the housing (7) defines a main space (8a) inside it, and that it further comprises a circuit board (15) that abuts against an inner surface of the housing (7), such that it divides the main space (8a) into a lower space (8b), in which the battery holder (13) is arranged, and an upper space (8c), located between the circuit board (15) and an upper face (5) of the housing (7).

4. A temperature triggered alarm arrangement (1) according to any one of the preceding claims, characterized in that the control unit (19) is configured to trigger the audible alarm generator (21) when a temperature increase rate, as measured by the temperature sensor (20), is above a predetermined rate threshold.

5. A temperature triggered alarm arrangement (1) according to any one of the preceding claims, characterized in that it is self-contained, as the electric power supply in the form of a battery (11), and the communication between the control unit (19) and the temperature sensor (20) and the communication between the control unit (19) and the audible alarm generator (21), are arranged within the housing (7).

6. A temperature triggered alarm arrangement (1) according to any one of the preceding claims, characterized in that the battery holder (13) is configured to receive a button cell battery (11) having a flat and circular shape and having a battery diameter, wherein the thermal convection channel (23) of the circuit board (15) and the layer aperture (25a) of the adhesive layer (25) both are arranged within the perimeter of the battery diameter.

7. A temperature triggered alarm arrangement (1) according to one of the preceding claims, characterized in that the battery holder (13) is configured to receive a button cell battery (11) having a substantially flat and circular shape with a battery diameter, and that it further comprises a circuit board (15) that is circular with a circuit board diameter which is less than 1.5 times larger than the battery diameter.

8. A temperature triggered alarm arrangement (1) according to one of the preceding claims, characterized in that the housing (107) has a cylindrical side wall (103) comprising a battery insertion opening (108), and that the cylindrical side wall (103) further comprises a battery removal opening (110) located diametrically opposite to the battery insertion opening (108).