EP2693415A1 - Leitungsansteuerung für ein Feueralarmsystem und entsprechendes Feueralarmsystem - Google Patents

Leitungsansteuerung für ein Feueralarmsystem und entsprechendes Feueralarmsystem Download PDF

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Publication number
EP2693415A1
EP2693415A1 EP13172598.8A EP13172598A EP2693415A1 EP 2693415 A1 EP2693415 A1 EP 2693415A1 EP 13172598 A EP13172598 A EP 13172598A EP 2693415 A1 EP2693415 A1 EP 2693415A1
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EP
European Patent Office
Prior art keywords
line
current
alarm
voltage
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13172598.8A
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English (en)
French (fr)
Inventor
Urs Kästli
Hong PANG
Shu Chun Hou
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens Schweiz AG
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Siemens AG
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Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP2693415A1 publication Critical patent/EP2693415A1/de
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
    • G08B25/01—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium
    • G08B25/04—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium using a single signalling line, e.g. in a closed loop
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/02—Monitoring continuously signalling or alarm systems
    • G08B29/06—Monitoring of the line circuits, e.g. signalling of line faults

Definitions

  • the present invention relates to the field of fire alarms in general, in particular to a line drive circuit in a fire alarm system and a drive method.
  • An automatic fire alarm system or fire alarm system for short, is a type of automatic fire control installation which people set up inside buildings or other areas so that they may discover and report a fire early, and take prompt and effective measures such as controlling and extinguishing the fire.
  • Fire alarm systems are installed in most buildings nowadays, such as office blocks, hotels and large shopping centres.
  • Fig. 1A shows the construction of a typical fire alarm system schematically.
  • a fire alarm system 100 typically comprises a central control system 110, and multiple fire detectors 120 and/or multiple manual alarms 130, etc. connected to the central control system 110 by lines "Line".
  • the fire detectors 120 and manual alarms 130 all transmit alarm signals to the central control system 110 via the lines "Line".
  • the central control system 110 automatically takes corresponding measures for extinguishing the fire and for communication.
  • the fire alarm system shown in Fig. 1A enables the alarm to be raised and the fire extinguished automatically, while also enabling safe dispersal and guidance, system process display, fire control file management, and so on, so as to form a complete fire-fighting control system.
  • An alternating current power supply 111 or storage battery power supply 112 can be used for the central control system 110 in Fig. 1A .
  • the storage battery 112 of the central control system 110 is generally required to be able to support the system for 72 hours of fire monitoring. In some countries, the storage battery 112 is also required to be able to support an alarm state for approximately half an hour. In order to meet these requirements, the central control system 110 must be as power-saving as possible.
  • the fire detector 120 is an instrument for detecting a fire. Since the onset of fire is accompanied by the generation of smoke, high temperatures and light, etc., this smoke, heat and light can be converted to electrical alarm signals by a smoke probe 120 ("S") or temperature probe 120 ("H"), so that the central control system automatically activates a fire-extinguishing device to promptly extinguish the fire.
  • the central control system 110 drives each fire detector 120 or manual alarm 130 via the lines "Line", so that they obtain enough electrical energy to operate normally. At the same time, the central control system 110 also monitors the lines periodically to detect whether an open circuit or short circuit fault has occurred, to guarantee the normal operation of the fire detectors 120 and manual alarms 130.
  • Fig. 1B shows how the fire detectors 120 for example are specifically connected to the central control system 110.
  • multiple fire detectors 120 are connected in parallel between lines Line+ and Line-, while a terminating element (EOL: End of Line) is connected to the far end of the line "Line".
  • the terminating element EOL may be a resistive element, for detecting whether the line has a fault. Specifically, when an open circuit occurs in a line "Line", the line resistance detected from the central control system 110 side will be higher than the resistance of the EOL; when a short circuit occurs in a line "Line", the line resistance detected from the central control system 110 side will be lower than the resistance of the EOL.
  • the EOL can assist in detecting whether the line is normal.
  • the central control system 110 also monitors the line voltage V Line so as to monitor whether an alarm has arisen on a line.
  • the fire detectors 120 will send an alarm signal along the line "Line" when they detect a fire, for example by pulling down the line voltage V Line .
  • Figs. 2A and 2B show schematically how two types of fire detector 120 currently in common use indicate an alarm.
  • the fire detector 120-1 shown in Fig. 2A closes a switch K1 when a sensing module 220 thereof detects a fire; the switch K1 is connected in series with a Zener diode (with a reverse breakdown voltage of about 5.6 V, for example) between Line+ and Line- of the line.
  • the closing of the switch K1 causes the line voltage to be pulled down from its normal value, such as 24 V, to the reverse breakdown voltage of the Zener diode, which is 5.6 V.
  • the central control system 110 can discover a fire by detecting the drop in line voltage.
  • Fig. 2B shows another way in which a fire detector 120-2 gives an alarm.
  • a sensing module 220 thereof detects a fire
  • a switch K2 is closed; the switch K2 is connected in series with a small resistor (e.g. 450 ohms) between Line+ and Line- of the line.
  • a small resistor e.g. 450 ohms
  • the embodiments of the present invention propose a drive circuit in a fire alarm system, the drive circuit being used to drive a line connected to one or more fire detectors.
  • the drive circuit being used to drive a line connected to one or more fire detectors.
  • fire detectors of the two types shown in Figs. 2A and 2B can be supported in a self-adaptive manner, while also achieving the objective of saving power.
  • the drive circuit is used to supply electrical energy to a line connected to one or more fire detectors, and comprises: a current generation circuit, capable of selectively supplying either a first current I N1 or a second current I ALARM to the line, wherein the first current I N1 is used as a line monitoring current in a normal operating state, and the second current I ALARM is greater than the first current I N1 ; a detection circuit, for detecting whether a line voltage on the line is lower than a threshold, and when the line voltage is lower than the threshold V th , controlling the current generation circuit to supply the second current I ALARM to the line "Line", wherein the threshold V th is lower than a normal line voltage but higher than a maximum alarm voltage V Alarm indicated on the line when the fire detector gives an alarm.
  • a current generation circuit capable of selectively supplying either a first current I N1 or a second current I ALARM to the line, wherein the first current I N1 is used as a line monitoring current in a normal operating state, and the second current I AL
  • the size of the second current I ALARM enables the maximum alarm voltage V Alarm to be maintained for a predetermined time period, so that the fire alarm system detects the alarm voltage V Alarm .
  • the first current I N1 > (maximum number of fire detectors which can be connected to the line x quiescent current of each fire detector + minimum forward current of the End of Line element EOL).
  • the drive circuit can supply a small monitoring current I N1 in a monitoring stage and a larger alarm current I ALARM in an alarm stage.
  • I N1 a small monitoring current
  • I ALARM an alarm current
  • the detection circuit comprises: a threshold judgment circuit, connected to the line "Line” and used for judging, in a hardware manner, whether the line voltage V Line is lower than the threshold V th ; and a control circuit, for controlling the current generation circuit to be switched from supplying the first current I N1 to supplying the second current I ALARM when the line voltage V Line is lower than the threshold V th . Since the drive circuit uses a hardware detection circuit to accomplish threshold judgment and feedback control, the drive circuit can detect an alarm signal in a very short time, and supply a larger alarm current I ALARM to maintain an alarm signal from a fire detector such as that shown in Fig. 2B .
  • the threshold judgment circuit comprises: a series branch, the two ends of which are coupled to the line voltage V Line , the series branch comprising at least one Zener diode and a first resistor, wherein the sum of reverse breakdown voltages of the at least one Zener diode is equal to the threshold V th ; and the control circuit uses a voltage at a connection point between the first resistor and the Zener diode as a threshold judgment result, for controlling the current generation circuit.
  • the control circuit comprises a switch circuit for converting the threshold judgment result to a switching value.
  • a Zener diode is used as a threshold judgment element in this embodiment, being distinguished by a simple structure and a fast response.
  • the current generation circuit is preferably a current source.
  • the current source comprises: a transistor, connected to form a common-emitter circuit, and used for supplying a current to the line "Line"; a variable resistance circuit, connected to the emitter of the transistor, and having a resistance capable of being switched between at least a first resistance value and a second resistance value; and a voltage control circuit, for stabilizing the voltage across the variable resistance circuit at a predetermined voltage; wherein the variable resistance circuit switches the resistance value thereof in response to a control signal from the detection circuit.
  • the variable resistance circuit comprises: at least two resistance branches connected in parallel, wherein a controlled switch is provided on at least one of the resistance branches, the controlled switch closing in response to a control signal from the detection circuit.
  • the current source comprises: a transistor, connected to form a common-emitter circuit, for drawing a current from the line "Line", a second resistor being connected to the emitter thereof; a voltage control circuit, for stabilizing the voltage across the second resistor at either a first voltage value or a second voltage value, wherein the voltage control circuit switches the first voltage value to the second voltage value in response to a control signal from the detection circuit.
  • a fire alarm system comprises: one or more fire detectors, for detecting whether a fire has arisen in a neighborhood thereof; the drive circuit as described above, for supplying electrical energy to a line connected to one or more fire detectors; an End of Line element (EOL), connected at a remote end of the line, and used to terminate the line.
  • EOL End of Line element
  • the End of Line element (EOL) is a transient voltage suppressor (TVS).
  • the fire detector comprises at least one detector which requires an additional current to maintain an alarm voltage thereof when giving an alarm.
  • a line drive method for a fire alarm system comprising: in a normal operating state, supplying a first current I N1 to the line, wherein the first current I N1 is used as a line monitoring current in the normal operating state; detecting a line voltage V Line on the line; judging whether the line voltage V Line is lower than a threshold V th , wherein the threshold V th is lower than a normal line voltage but higher than a maximum alarm voltage V Alarm indicated on the line when the fire detector gives an alarm; if it is judged that the line voltage V Line is lower than the threshold V th , switching the current supplied to the line from the first current I N1 to the second current I ALARM , the second current I ALARM being greater than the first current I N1 .
  • the size of the second current I ALARM is enough to enable the maximum alarm voltage V Alarm to be maintained for a predetermined time period, so
  • a fire alarm system needs to be compatible with the two types of fire detector shown in Figs. 2A and 2B , but these two types of fire detector have different alarm voltages (e.g. 5.6 V and 12 V, respectively); moreover, in the case of the fire detector shown in Fig. 2B , a relatively large current is also required to maintain the alarm state thereof, otherwise the fire detector will mistakenly reset automatically.
  • the inventors of the present invention put forward the concept of supplying different line drive currents in a line monitoring stage and an alarm stage in the following embodiments.
  • a lower current is used to monitor whether the line is normal in a line monitoring stage, and a higher current is used to maintain an effective alarm signal when an alarm is discovered, to avoid erroneous resetting of the fire detector.
  • This concept can support both types of fire detector, with no need to identify the detector type in advance. Furthermore, this concept achieves the objective of saving power by having power supplied at a low current in the monitoring stage.
  • Fig. 3 shows a line drive circuit 300 for a fire alarm system according to one embodiment of the present invention, and a fire detector 120 and EOL connected to the drive circuit 300 by a line "Line".
  • the drive circuit 300 supplies a line current I Line to the line "Line”.
  • the fire detector 120 is connected between Line+ and Line- of the line.
  • the remote end of the line is terminated by an End of Line element (EOL), which is for example a resistive element or preferably a transient voltage suppressor (TVS).
  • EOL End of Line element
  • Vd V Line - V R , wherein V Line is the line voltage observed at the drive circuit 300 side.
  • the current flowing through the fire detector 120 is Id.
  • the current flowing through the End of Line element EOL at the remote end is I EOL .
  • the drive circuit 300 comprises a current generation circuit 310 and a detection circuit 320.
  • the current generation circuit 310 can selectively supply at least two line currents I Line of different sizes to the line "Line", i.e. either a first current I N1 or a second current I ALARM .
  • the first current I N1 is used as a line monitoring current in a normal operating state
  • the second current I ALARM is used as an alarm current when an alarm is given, the second current I ALARM being greater than the first current I N1 .
  • the detection circuit 320 is connected to the line, and used to control the current generation circuit 310, via a control path C1, to supply the second current I ALARM to the line "Line” when detecting that the line voltage V Line on the line "Line” is lower than a threshold V th (which indicates that an alarm signal has arisen on the line).
  • the threshold V th can be set to be lower than a normal voltage on the line, and higher than a maximum alarm voltage V Alarm indicated on the line "Line” when the fire detector 120 gives an alarm. Supposing the fire detector connected to the line comprises the two detectors 120-1 and 120-2 shown in Figs. 2A and 2B , then V th can be set to be greater than 12 V, for instance, which is the alarm voltage of the fire detector 120-2.
  • the detection circuit 320 can specifically comprise two parts, one being a threshold judgment circuit 321 and the other being a control circuit 325.
  • the threshold judgment circuit 321 is coupled to the line, and used for judging whether the line voltage V Line is lower than the threshold V th (e.g. 12 V).
  • the control circuit 325 switches the current generation circuit 310 from supplying the first current I N1 to supplying the second current I ALARM when the line voltage V Line drops below the threshold V th .
  • the small current I N1 is used for monitoring in a normal state, and the large current I ALARM is used to maintain an alarm signal in an alarm state. In this way, not only can fire detectors of different types be supported, but power can also be saved in the central control system.
  • Fig. 4 shows a drive circuit 400 according to another embodiment of the present invention.
  • the current generation circuit 410 is preferably two current sources connected in parallel, for instance, a controlled switch K being provided on an output path of one of these current sources.
  • the controlled switch K In the normal state, the controlled switch K is open, and a first current source alone supplies a monitoring current I N1 to the line "Line".
  • ALARM alarm
  • the detection circuit 420 comprises a series branch used for threshold judgment, connected between Line+ and Line- of the line.
  • the series branch comprises a Zener diode D1 and a resistor R3.
  • the output of the detection circuit 420 is the voltage Vt at the connection point between the Zener diode D1 and the resistor R3.
  • the reverse breakdown voltage of the Zener diode is the threshold voltage V th , for example 15 V (greater than the maximum alarm voltage, 12 V, of the fire detector).
  • V th for example 15 V (greater than the maximum alarm voltage, 12 V, of the fire detector).
  • the Zener diode D1 could also be replaced by two or more Zener diodes, in which case the sum of the reverse breakdown voltages of these Zener diodes would be the threshold voltage V th .
  • the control circuit is simplified to using the voltage Vt directly to control the closing or opening of the switch K via a control path C1.
  • Fig. 4 shows a simple manner of implementation.
  • Fig. 5 shows waveforms of current and voltage on the line in the example shown in Fig. 4 .
  • V AL 12 V or 5.6 V.
  • the fire detector then resets automatically and enters the next cycle of normal operation.
  • I N1 is, for instance, about 6 mA
  • I AL is about 24 mA
  • the sizes of I N1 and I AL can be suitably chosen according to requirements.
  • I ALARM must supply a large current, so that the alarm voltage of the fire detector shown in Fig. 2B can be kept at, for instance, 12 V.
  • the alarm voltage can be kept above 12 V if I ALARM is approximately 30 mA, and so this is sufficient to avoid automatic resetting of the detector.
  • I ALARM is approximately 30 mA, and so this is sufficient to avoid automatic resetting of the detector.
  • those skilled in the art can choose the size of I ALARM appropriately according to actual requirements.
  • Fig. 6 shows by way of example a specific circuit structure of the block diagram shown in Fig. 3 .
  • the drive circuit 600 comprises a current generation circuit 610 and detection circuit 620.
  • the current generation circuit 610 is preferably a current source with a variable output current.
  • the current source comprises a transistor V101, which operates in an amplifying state and is connected to form a common-emitter circuit, a variable resistance circuit 612 connected in series to the emitter of the transistor V101, and a voltage control circuit 613 for controlling the voltage across the variable resistance circuit 612.
  • the transistor V101 in the current source is, for instance, a PNP-type transistor, the collector C thereof being connected to the line "Line" as an output electrode.
  • the emitter E of the transistor V101 is also connected to Vcc via the variable resistance circuit 612.
  • Fig. 6 shows a scheme in which a PNP-type transistor is used to realize the current source, those skilled in the art can appreciate that the current source could also be realized using another circuit used to set up a current source, such as an NPN-type transistor, MOSFET or op-amp.
  • a stable reference voltage Vref is obtained at point R once Vcc has been divided by the series resistors R118, R114 and R119.
  • a Zener diode 614 is used to stabilize the voltage across the series resistors R118 and R114.
  • the voltage control circuit 613 acquires a sample voltage from the emitter E of the transistor, and compares this sample voltage with the reference voltage Vref; the comparison result is preferably used to control the base B of the transistor V101 after proportional integration (PI), and hence adjust the size of V CE .
  • PI proportional integration
  • the size of the current outputted by the transistor V101 is determined by the resistance of the variable resistance circuit 612 connected in series with the emitter E of V101.
  • the variable resistance circuit 612 comprises two resistance branches R108 and R111, connected in parallel with each other.
  • a controlled switching element K is further provided in the resistance branch in which R111 is located, the controlled end of K being connected to the output end of the detection circuit 620.
  • the controlled switching element K is preferably a MOSFET V102, the gate G thereof being the controlled end.
  • Fig. 6 shows a solution in which a variable emitter resistance is used to regulate the output current
  • the current generation circuit 610 could also selectively supply two drive currents of different sizes in other ways.
  • the current generation circuit 610 could also supply a switchable output current by means of a voltage source and a variable resistance.
  • the current generation circuit 610 could also be a current sink used to draw current from the line.
  • the current sink could, for instance, consist of a transistor connected to form a common-emitter circuit, the collector of the transistor being the output end, and the emitter being connected to ground via a second resistance.
  • a voltage control circuit is used to stabilize the voltage across the second resistance at either a first voltage value or a second voltage value, wherein the voltage control circuit can switch the first voltage value to the second voltage value in response to a control signal from the detection circuit (620).
  • the detection circuit 620 comprises a Zener diode V112 and a resistor R121 connected in series therewith; the Zener diode and resistor are connected in series between Line+ and Line-, and used as a threshold judgment circuit 621.
  • the reverse breakdown voltage of the Zener diode V112 is equal to the threshold V th , e.g. 15 V.
  • the Zener diode V112 may be replaced by multiple Zener diodes, the sum of reverse breakdown voltages of the multiple Zener diodes being equal to the threshold V th .
  • a control circuit 625 regards a voltage Vp at a joining point P between the Zener diode V112 and resistor R121 as a threshold judgment result.
  • the control circuit 625 comprises a switch circuit for converting Vp to a switching value, the switch circuit comprising cascaded transistors V109 and V107. Both transistors V107 and V109 are connected to form a common-emitter circuit, wherein Vp is the input of V109, and the output of V109 serves as the input of V107.
  • the output of V107 is used to control the controlled end of switch K in the variable resistance circuit 612.
  • Vp changes from HIGH to ground (GND), causing cut-off of the transistor V109 which was originally conducting, so that V Alarm_Line changes to HIGH.
  • V107 Driven by the HIGH V Alarm_Line , V107 conducts, so that the collector C end of V107 changes to LOW, thereby causing the MOSFET V102 to conduct, i.e. connecting resistors R111 and R108 in parallel. In this way, a larger drive current can be supplied on the line in response to an alarm signal, to maintain the alarm voltage.
  • Fig. 7 shows by way of example a line drive method according to an embodiment of the present invention for the fire alarm system shown in Fig. 1B , for instance.
  • the fire detectors connected into the line may comprise the detector(s) shown in Fig. 2A and/or Fig. 2B .
  • the line drive method begins with step S710.
  • step S710 a first current I N1 is supplied to the line "Line” in a normal operating state, wherein the first current I N1 is used as a line monitoring current in the normal operating state.
  • step S720 a line voltage V Line on the line "Line” is detected.
  • step S730 it is judged whether the line voltage V Line is lower than a threshold V th , the threshold V th being lower than a normal line voltage but higher than a maximum alarm voltage V Alarm indicated on the line when a fire detector gives an alarm. For example, if V Alarm is the alarm voltage of the detector shown in Fig. 2B , e.g. 12 V, then 15 V, for instance, can be chosen as V th . If the judgment result is negative, then the method flow returns to step S720, to detect the line voltage V Line again. If the judgment result is positive, this indicates that an alarm has arisen, and so the method flow proceeds to step S740.
  • V Alarm is the alarm voltage of the detector shown in Fig. 2B , e.g. 12 V
  • 15 V for instance
  • step S740 the current supplied to the line "Line" is switched from the first current I N1 to a second current I ALARM .
  • I ALARM > I N1 .
  • the size of the second current I ALARM is sufficient to enable the maximum alarm voltage V Alarm to be maintained for a predetermined time period, so that the fire alarm system detects the alarm.

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  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire Alarms (AREA)
EP13172598.8A 2012-07-31 2013-06-19 Leitungsansteuerung für ein Feueralarmsystem und entsprechendes Feueralarmsystem Withdrawn EP2693415A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201210270657.0A CN103578218B (zh) 2012-07-31 2012-07-31 火警系统的线路驱动电路及相应的火警系统

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
GB2508033B (en) * 2012-11-20 2016-02-17 Sprue Safety Products Ltd Low power detection and alarm
JP2021103594A (ja) * 2017-07-21 2021-07-15 ホーチキ株式会社 トンネル防災システム

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104897967B (zh) * 2014-03-04 2019-02-01 西门子瑞士有限公司 火警系统的现场连线检测装置及方法
CN108616792B (zh) * 2018-06-26 2024-05-24 宗仁科技(平潭)股份有限公司 模仿警报声的集成电路和报警装置
CN113313922A (zh) * 2021-05-31 2021-08-27 陕西建工智能科技有限公司 施工现场火灾自动报警系统线路状态在线监测装置及方法

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US5670937A (en) * 1995-05-16 1997-09-23 General Signal Corporation Line monitor for two wire data transmission
US20070001819A1 (en) * 2005-06-30 2007-01-04 Becker Donald E Fire alarm notification power supply with configurable notification appliance circuits and auxiliary power circuits apparatus and method
EP2136343A1 (de) * 2008-06-18 2009-12-23 GEZE GmbH Leitungsüberwachung von Rauchschaltern

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JP4789318B2 (ja) * 2000-10-18 2011-10-12 矢崎総業株式会社 火災警報装置及びガス火災感知器
CN102176181B (zh) * 2011-01-17 2016-05-25 深圳前海奥瑞那安全技术有限公司 一种点型光电感烟探测器的恒流源供电电路

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US5670937A (en) * 1995-05-16 1997-09-23 General Signal Corporation Line monitor for two wire data transmission
US20070001819A1 (en) * 2005-06-30 2007-01-04 Becker Donald E Fire alarm notification power supply with configurable notification appliance circuits and auxiliary power circuits apparatus and method
EP2136343A1 (de) * 2008-06-18 2009-12-23 GEZE GmbH Leitungsüberwachung von Rauchschaltern

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2508033B (en) * 2012-11-20 2016-02-17 Sprue Safety Products Ltd Low power detection and alarm
US9824561B2 (en) 2012-11-20 2017-11-21 Sprue Safety Products, Ltd. Low power detection and alarm
JP2021103594A (ja) * 2017-07-21 2021-07-15 ホーチキ株式会社 トンネル防災システム
JP7075524B2 (ja) 2017-07-21 2022-05-25 ホーチキ株式会社 トンネル防災システム

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RU2013135767A (ru) 2015-02-10
CN103578218B (zh) 2016-05-18

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