Sensor

Abstract

To allow air from the outside to favorably flow into a detection space.SOLUTION: There are provided a first case attached to a detection site, a second case having a cylindrical portion extending in an axial direction, a bottom portion formed at one end of the cylindrical portion in the axial direction, and an opening portion formed at the other end of the cylindrical portion in the axial direction, and a third case holding a detection element, a control unit that controls the detection element, and a transmission unit that transmits a signal detected by the detection element to the outside. A plurality of ventilation windows extending in the axial direction are formed in the cylindrical portion of the second case in the circumferential direction, one end side of the ventilation window in the axial direction corresponds to the position of the detection space, and the other end side in the axial direction corresponds to the position of the first case. The opening area of the ventilation window can be set to a size sufficient for the area of the detection space. By providing the air guide portion in the first case, the second case, and the third case, the air on the air flow upstream side can be guided from the ventilation window to the detection space, and the air from the detection space can be guided to the ventilation window on the air flow downstream side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a detector, which is useful as a smoke detector to be installed near electrical wiring or transformers in factories where there is a high risk of fire, for example. [Background technology]

[0002] A smoke detector in which an insect screen is supported by an air guide section is disclosed in Patent Document 1. In Patent Document 1, the air guide section is provided with a light blocking function to form a labyrinth wall. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-227446 Summary of the Invention [Problem to be solved by the invention]

[0004] The smoke detector shown in Patent Document 1 has ventilation windows, an insect screen, and a labyrinth wall located only on the periphery of the detection space. The insect screen has a fine mesh for its function. The labyrinth also has a maze structure for its function. As a result, the insect screen and labyrinth may obstruct the flow of smoke, making it difficult to efficiently guide smoke into the detection space.

[0005] In view of the above, an object of the present disclosure is to prevent the air flow from being obstructed by a ventilation window or an air guide section, in other words, to allow air from the outside to flow smoothly into the detection space. [Means for solving the problem]

[0006] The sensor of the present disclosure comprises a first case (120) attached to a detection site, a second case (130) having an axially extending cylindrical portion (135), a bottom portion (134) formed at one axial end of the cylindrical portion, and an opening portion (136) formed at the other axial end of the cylindrical portion, and a third case (150) that holds a detection element, a control portion (141) that controls the detection element, and a transmission portion (142) that transmits a signal detected by the detection element to the outside. The first case is held inside the second case on the opening side of the second case, and the third case is held inside the second case on one axial end side of the first case, and the second case forms a detection space for detection by the detection element on one axial end side of the third case.

[0007] In the sensor of the present disclosure, a plurality of axially extending ventilation windows are formed circumferentially in the cylindrical portion of the second case, with one axial end of each ventilation window corresponding to the position of the detection space and the other axial end corresponding to the position of the first case. The first, second, and third cases are each formed with an air guide section that guides air upstream in the air flow from the ventilation window to the detection space and guides air from the detection space to the ventilation window downstream in the air flow.

[0008] In the sensor of the present disclosure, a detection space, a third case, and a first case are arranged inside the second case from one end in the axial direction. That is, the detection space is formed in the second case at a position further axially toward one end than the positions where the first case and the third case are arranged. In contrast, a ventilation window is formed in the cylindrical portion of the second case, extending from one end to the other in the axial direction. Furthermore, multiple ventilation windows are formed in the circumferential direction. Therefore, the opening area of ​​the ventilation window can be set to a size sufficient for the area of ​​the detection space.

[0009] In the sensor of the present disclosure, the ventilation window extending in the axial direction faces the detection space located at one axial end of the second case, the third case located in the axial middle, and the first case located at the other axial end. Therefore, in the sensor of the present disclosure, air guide sections are formed in the first case, the second case, and the third case to connect the ventilation window and the detection space. This allows air from the upstream side of the air flow to be guided from the ventilation window to the detection space, and air from the detection space to be guided to the ventilation window on the downstream side of the air flow. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a smoke detector according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the smoke detector. [Figure 3] FIG. 2 is a perspective view showing a first case. [Figure 4] FIG. 3 is an axial cross-sectional view of the first case. [Figure 5] FIG. 4 is a perspective view showing a third case. [Figure 6] FIG. 6 is a cross-sectional view of the third case taken along line VI-VI in FIG. [Figure 7] FIG. 4 is a perspective view showing a second case. [Figure 8] FIG. 4 is an axial cross-sectional view of the second case. [Figure 9] 9 is a cross-sectional view of the second case taken along line IX-IX in FIG. 1. FIG. [Figure 10] FIG. 2 is a cross-sectional view of the second case taken along line XX in FIG. [Figure 11] FIG. 2 is a cross-sectional view showing the arrangement of a detector and a detection space. [Figure 12] FIG. 10 is a cross-sectional view showing the arrangement of the warning light and the insect screen. [Figure 13] FIG. 2 is a perspective view showing the arrangement of smoke detectors. [Figure 14] FIG. 1 is a diagram illustrating the flow of air into and out of a smoke detector. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 shows an example of a detector according to the present disclosure used as a smoke detector 100. The smoke detector 100 is installed, for example, near electrical wiring or transformers in a factory where there is a high risk of fire. Therefore, the smoke detector 100 is installed in a location where electromagnetic wave resistance is required. The smoke detector 100 is small enough to be held by a worker in one hand. The smoke detector 100 has a cylindrical shape with a diameter of approximately 50 millimeters and a height of approximately 45 millimeters. The total weight is approximately 50 grams.

[0012] FIG. 2 shows an exploded view of each component of this smoke detector 100. In FIG. 2, one axial end is at the bottom and the other axial end is at the top. Arranged from the other axial end (top) are the first case 120 and the third case 150 in that order. Then, the second case 130 is arranged so as to cover the first case 120 and the third case 150. Therefore, the first case 120 and the third case 150 are held inside the second case 130.

[0013] The first case 120 has an opening at the other axial end, and the base 110 is disposed in the opening. Therefore, the base 110 is a component that forms part of the first case 120. The base 110 is made of a non-conductive resin material, such as ABS resin (acrylonitrile butadiene styrene resin). The base 110 is formed into a disk shape by injection molding the ABS resin. As mentioned above, its diameter is approximately 50 millimeters. The base 110 is fixed to the detection target location using screws or double-sided tape. The detection target location is usually the ceiling of a building. However, in factory buildings, ventilation openings are often installed in the ceiling, and air is often blown downward from the ventilation openings. Therefore, even when a fire breaks out, smoke does not reach the ceiling easily. If smoke fills the area near the ceiling, the fire may have progressed significantly.

[0014] The smoke detector 100 in this example is placed on the production line, not on the ceiling of a factory building. Specifically, as shown in FIG. 13, the smoke detector 100 is placed in a control box 200 where electrical wiring is concentrated, or in a transformer box that houses a transformer. Alternatively, the smoke detector 100 is placed in a safety case that houses cutting machines and soldering machines on the production line. Both are closed spaces that quickly fill with smoke in the event of a fire. Therefore, the base 110 is fixed to a top plate 201 of the space containing the control box 200, etc. Therefore, the detection area in this example is near the expected source of smoke. Since screwing requires additional processing of the top plate 201, the base 110 in this example is mainly fixed to the top plate 201 with double-sided tape.

[0015] 13 shows an example where the smoke detector 100 is fixed to the side wall 202, in addition to an example where the smoke detector 100 is fixed to the top panel 201. However, two smoke detectors 100 are not normally placed in one control box 200. FIG. 13 shows the smoke detector 100 being fixed to the side wall 202 in order to explain the placement example. As shown in FIG. 13, when the smoke detector 100 is fixed to the side wall 202, it is desirable to fix it in an upper position. Furthermore, since the control box 200 is normally provided with a fan 203 for exhausting heat, it is desirable to place the smoke detector 100 in a position near the fan 203 where it is affected by the air flow caused by the fan 203.

[0016] Typically, several tens to around 200 smoke detectors 100 are installed on one production line. Each smoke detector 100 is equipped with a transmitter 142, which will be described later. Signals from each smoke detector 100 are transmitted wirelessly to a receiver installed on the production line. The signals from each smoke detector 100 received by the receiver are sent to a management server installed at a location away from the production line via a communication line such as the Internet and / or an intranet cloud system. The communication line of the cloud system or the like may be wired and / or wireless.

[0017] Like the base 110, the first case 120 is made of a non-conductive resin material. The first case 120 is also formed by injection molding of ABS resin. The first case 120 holds a battery 121 inside. Specifically, battery fixing tabs formed on the first case 120 are elastically deformed to hold the battery 121 by their own elasticity. The battery 121 is electrically connected to a power connector 145 arranged on a board assembly 140, which will be described later. The power connector 145 electrically connects the negative terminal to a ground conductor film formed on the board assembly 140. The positive terminal is also electrically connected to a power conductor film formed on the board assembly 140. In this example, a 3-volt battery 121 is used.

[0018] Snap-fit ​​claws are formed on the base 110 at locations corresponding to the recesses 111. Then, the first case 120 is formed with connecting portions 122 that fit into the snap-fit ​​claws of the base 110. By rotating the first case 120 in accordance with the base 110, the connecting portions 122 of the first case 120 can be engaged with or detached from the snap-fit ​​claws of the base 110.

[0019] The second case 130 is also made of a non-conductive resin material and is formed by injection molding of ABS resin. The second case 130 has a cylindrical shape with one axial end (the lower end in FIG. 2) closed and the other axial end (the upper end in FIG. 2) open. The bottom 134 formed at the one axial end is hemispherical. The side of the second case 130 is a cylindrical portion 135, and this cylindrical portion 135 has multiple ventilation windows 131 extending in the axial direction formed in the circumferential direction. In this example, the ventilation windows 131 are formed in 16 locations equally spaced apart in the circumferential direction. A detection space 132 is formed in the center of the upper surface of the hemispherical bottom 134 of the second case 130. In this example, the detection space 132 is a smoke detection space for detecting smoke.

[0020] One axial end of the ventilation window 131 corresponds to the position of the detection space 132, and the other axial end corresponds to the position of the first case 120. That is, the ventilation window 131 is formed over substantially the entire axial length from one axial end to the other axial end.

[0021] The other axial end of second case 130 forms opening 136, and an engagement claw is formed on the inner periphery of opening 136. Second case 130 is fixedly connected to first case 120 by this engagement claw. Therefore, when first case 120 is attached to base 110 as described above, all components of smoke detector 100 held in second case 130, including battery 121 held in first case 120 and third case 150 (described later), are fixed to or detached from base 110.

[0022] A third case 150 is held inside the second case 130 at one axial end of the first case 120. The third case 150 has a container shape with the other axial end open, and a board assembly 140 is disposed in the opening of the third case 150. The board assembly 140 is a member that covers the opening of the third case 150 and forms part of the third case 150. The third case 150 is made of a conductive resin material. The third case 150 is injection molded from a resin material, for example, a blend of PA6 resin (6 nylon resin) and CF30 resin (carbon fiber reinforced resin). As described above, the third case 150 has a container shape with one side (the other axial end) open, and holds a light emitting element 151 and a light receiving element 152 inside the container shape. More specifically, third case 150 holds light-emitting element 151 and light-receiving element 152 in positions where light-emitting element 151 and light-receiving element 152 face detection space 132. In smoke detector 100 of this example, light-emitting element 151 and light-receiving element 152 function as the detector's detection element. Note that the detection element of smoke detector 100 may be provided by a chemical gas sensor that detects gas components.

[0023] An insect screen 160 is disposed radially inside the cylindrical portion 135 of the second case 130 to prevent foreign matter from entering the detection space 132 through the ventilation window 131. A typical example of foreign matter is an insect, so it is called an insect screen 160, but the insect screen 160 is not limited to insects and also prevents the entry of foreign matter such as dust.

[0024] The outline of the configuration of smoke detector 100 has been explained above with reference to Fig. 2. Next, we will explain the details of first case 120, second case 130, and third case 150. In particular, we will explain the configuration of the air guidance section that guides air (smoke) upstream in the air flow from ventilation window 131 to detection space 132, and also guides air from detection space 132 to ventilation window 131 downstream in the air flow.

[0025] 3 and 4 show the first case 120. These figures show the state in which the base 110 has been removed from the first case 120 and the insect screen 160 has been attached to the first case 120. The insect screen 160 has a generally cylindrical shape, and its other axial end is held by the first case insect screen holding groove 123 of the first case 120. The other axial end of the insect screen 160 faces the ventilation window 131. However, the other axial end of the ventilation window 131 extends further toward the other end than the insect screen 160 and faces the outer periphery of the first case 120. The insect screen 160 in this example is made of non-conductive stainless steel and has a diameter of approximately 0.1 mm and a mesh size of approximately 60. Therefore, the mesh spacing is approximately 0.2 to 0.3 mm.

[0026] As described above, first case 120 faces the other axial end of ventilation window 131. A first case air guide section 124 is formed at a position facing ventilation window 131 to guide inflow air (smoke) from ventilation window 131 and outflow air toward ventilation window 131. A tapered section 125, whose diameter decreases toward the axial end, is formed on the inner periphery of first case 120 at a portion facing ventilation window 131 on the axial end side of first case insect screen holding groove 123. First case air guide section 124 is composed of two sections: first case air guide section first section 1241 and first case air guide section second section 1242. First case air guide section first section 1241 faces ventilation window 131 on the radial outside of first case insect screen holding groove 123. First case air guide section first portion 1241 guides air from the other axial end side of ventilation window 131 toward tapered section 125. On the other hand, first case air guide section second portion 1242 faces ventilation window 131 on the radially inner side of first case insect screen holding groove 123. First case air guide section second portion 1242 is formed in tapered section 125 and guides the air flow along the outer periphery of tapered section 125.

[0027] Next, the third case 150 will be described using FIGS. 5 and 6. FIG. 5 shows the external appearance of only the third case 150, including the board assembly 140. FIG. 6 shows a cross section of the third case 150 held in the second case 130. A third case air guide section 155 that guides air flow between the ventilation window 131 and the detection space 132 is also formed on the outer periphery of the third case 150. When the first case 120 and the third case 150 are held inside the second case 130, one axial end of the first case air guide section second portion 1242 coincides with the other axial end of the third case air guide section 155. As shown in FIG. 6, one axial end of the third case air guide section 155 is bent to form a labyrinth wall. In addition to the air flow guiding function described above, the third case air guide section 155 has a light-shielding function that blocks external light from entering the detection space 132 through the ventilation window 131. However, blocking external light is not required to be 100%. In this disclosure, blocking external light means preventing the entrance of an amount of external light that would adversely affect the light receiving element 152.

[0028] The light-emitting element 151 arranged inside the third case 150 is an LED that projects light toward the detection space 132, and projects light with an intensity of, for example, about 20 milliwatts. As shown in Figures 6 and 11, a light-emitter holding groove 156 through which the light projected from the light-emitting element 151 passes is formed in the portion of the third case 150 between the light-emitting element 151 and the detection space 132. This light-emitter holding groove 156 has a width of about 4 millimeters, and the light from the light-emitting element 151 reaches the detection space 132 from the light-emitter holding groove 156.

[0029] The light receiving element 152 is a photodiode that detects scattered light when smoke is introduced into the detection space 132 and the light projected from the light emitting element 151 is diffused by the smoke. As shown in FIGS. 6 and 11 , a light receiving groove 157 is formed in the third case 150 between the light receiving element 152 and the detection space 132, through which the light emitted in the detection space 132 passes toward the light receiving element 152. Like the light projecting groove 156, the light receiving groove 157 has a groove width of approximately 4 millimeters. The light receiving element 152 is disposed away from the optical axis of the light emitting element 151. In other words, the light receiving element 152 does not directly detect the light projected from the light emitting element 151, but rather detects the scattered light diffused by the smoke. Because the scattered light diffused by the smoke is weak, the output signal from the light receiving element 152 is a weak current of approximately several nanoamperes.

[0030] Since the third case 150 is made of a conductive resin material, the light emitting element 151 is held by a light emitting element holder 153 made of ABS resin, a non-conductive resin material. The light emitting element 151 is electrically insulated from the third case 150 and the board assembly 140 by this light emitting element holder 153. Similarly, the light receiving element 152 is held by a light receiving element holder 154 made of ABS resin, a non-conductive resin material, and is electrically insulated from the third case 150 and the board assembly 140. The light emitting element holder 153 is held in the light emitting holding groove 156 described above. Furthermore, the light receiving element holder 154 is held in the light receiving holding groove 157.

[0031] As described above, the board assembly 140 forms part of the third case 150. The board assembly 140 is placed on the opening of the third case 150, and the opening is closed by the board assembly 140, thereby forming the third case 150. As shown in FIG. 5 , the board assembly 140 holds a control unit 141, a transmitting unit 142, an output antenna 143, an indicator light 146, and a power connector 145. The control unit 141 is a one-chip microcomputer including a CPU that controls the light-emitting element 151 and the light-receiving element 152, and is equipped with an internal temperature sensor. The control unit 141 also monitors the remaining charge of the battery 121.

[0032] The transmitter 142 is a communication module that transmits signals to the outside and has an internal transmission circuit. The transmitted signals include a steady-state signal and an alarm signal. The alarm signal is transmitted by the control unit 141 when the signal detected by the light-receiving element 152 is equal to or greater than a predetermined threshold, indicating the possibility of a fire. The alarm light 146 is an LED that lights up when an alarm signal is output. As described above, the smoke detector 100 of this example is placed in a closed space such as the control box 200, but is visible through gaps in the control box 200, so the alarm light 146 can be used to notify those around it that a fire has occurred.

[0033] The output antenna 143 is a monopole antenna made of copper wire insulated with polyethylene resin. The length of the output antenna 143 is determined according to the output frequency. Factory wireless communications use a transmission frequency that is lower than the frequency (2.4 GHz) used by Wi-Fi and Bluetooth (registered trademark) in order to improve diffraction and reach. The frequency used in this example is, for example, 920 MHz. As the frequency becomes lower, the wavelength of the radio waves becomes longer, and the length and surface area of ​​the output antenna 143 must be adjusted accordingly. In this example, the length of the output antenna 143 is set to approximately 80 millimeters.

[0034] The board assembly 140 has a four-layer structure separated by three insulating board layers. The first layer is a mounting surface 1401 on which the control unit 141 (CPU, etc.), transmission unit 142 (communication module), notification light 146, and power connector 145 are mounted. The second layer is a power supply conductor film. This second layer is made of copper foil with a thickness of about 18 micrometers. The power supply conductor film is electrically connected to the positive terminal of the battery 121 via the power connector 145, and positive power is supplied from the battery 121. The light-emitting element 151, light-receiving element 152, and notification light 146 are also electrically connected to this power supply conductor film 1403 and receive a supply of electricity.

[0035] The third layer of the board assembly 140 is a ground conductor film. This ground conductor film is made of a conductive metal material such as copper foil and has a thickness of approximately 18 micrometers, similar to the power conductor film. Because the ground conductor film is formed over almost the entire surface of the board assembly 140, the third case 150 has a ground conductor film that extends over its entire surface. Therefore, the third case 150, including the board assembly 140, functions as a shielding case that isolates the interior from electromagnetic noise. In other words, a closed space is formed by the ground conductor film of the board assembly 140 and the conductive third case 150, and this closed space serves as a shielding space, shielding the interior from electromagnetic waves. The ground conductor film is electrically connected to the negative terminal of the battery 121 via the power connector 145.

[0036] The fourth layer of the board assembly 140 is a circuit surface on which an amplifier circuit that amplifies a signal detected by the light receiving element 152 is mounted. In addition to the amplifier circuit, positive wiring that connects the power supply conductor film with the positive terminals of the light emitting element 151 and the light receiving element 152 is printed on the circuit surface. Negative wiring that connects the ground conductor film with the negative terminals of the light emitting element 151 and the light receiving element 152 is also printed on the circuit surface. In addition, the signal line of the light receiving element 152 is also printed on the circuit surface 1404. Since the fourth layer is located inside the third case 150, which is a closed container, the amplifier circuit and the like are reliably shielded from electromagnetic waves.

[0037] 7 to 10 show the second case 130. FIGS. 7 to 9 show a state in which the insect screen 160 is held in the second case 130. FIG. 9 shows a cross section at one axial end side of the ventilation window 131, and FIG. 10 shows a cross section at the ventilation window 131 portion. In the second case 130, a detection space 132 in which the detection elements (light-emitting element 151 and light-receiving element 152) detect smoke is formed on the other axial end side of the bottom 134. This detection space 132 is formed on one axial end side of the third case 150 in relation to the third case 150. A second case air guide section 137 is integrally formed with the second case 130 so as to surround the detection space 132. When the third case 150 is held inside the second case 130, the other axial end side of the second case air guide section 137 and one axial end side of the third case air guide section 155 coincide with each other. Therefore, second case air guide section 137 is also bent to form a labyrinth wall. Like third case air guide section 155, second case air guide section 137 has the function of guiding air flow, as well as the light blocking function of blocking external light from ventilation window 131 from entering detection space 132. As with third case air guide section 155 described above, the light blocking function is not required to block 100% of external light.

[0038] The second case 130 is formed with a second case insect screen holding groove 138 that holds one axial end of the insect screen 160. Therefore, one axial end of the insect screen 160 is fitted into and held in the second case insect screen holding groove 138. As described above, the other axial end of the insect screen 160 is fitted into and held in the first case insect screen holding groove 123. Therefore, the insect screen 160 is sandwiched from both sides in the axial direction. In relation to the cylindrical portion 135 of the second case 130, the insect screen 160 is disposed on the radially inner periphery of the cylindrical portion 135. As shown in FIGS. 8 and 10 , the cylindrical portion 135 has ribs 139 formed between the ventilation windows 131. In other words, the ventilation windows 131 are the spaces between adjacent ribs 139. An insect screen holding portion 1391 that protrudes toward the insect screen 160 is formed on the inner peripheral surface of the crosspiece portion 139. In relation to the air guide portion, the insect screen 160 is disposed radially outward of the first case air guide portion second portion 1242, the third case air guide portion 155, and the second case air guide portion 137. Therefore, the radial inside of the insect screen 160 is held by the first case air guide portion second portion 1242, the third case air guide portion 155, and the second case air guide portion 137. The radial outside of the insect screen 160 is held by the first case air guide portion first portion 1241 and the insect screen holding portion 1391 of the second case 130.

[0039] Next, the operation of the smoke detector 100 of this embodiment will be described. The smoke detector 100 is attached to the top panel 201 of the control box 200, which is a high-risk area in a factory due to fires. The control unit 141 periodically energizes the light-emitting element 151 to emit light. For example, the control unit 141 energizes the light-emitting element 151 for approximately 20 milliseconds once every 10 seconds. This saves power from the battery 121. The light-receiving element 152 is also activated in synchronization with the timing at which the light-emitting element 151 emits light. When there is no fire, no smoke flows into the detection space 132, and the light from the light-emitting element 151 is not scattered. Furthermore, external light is blocked by the labyrinth walls of the second case air guide section 137 and the third case air guide section 155. Therefore, the light-receiving element 152, which is activated at the predetermined timing, does not detect light.

[0040] In this way, the light-emitting element 151 and the light-receiving element 152 periodically determine the presence or absence of smoke. The control unit 141 periodically transmits information from the transmission unit 142, even when there is no fire. This periodically transmitted information includes a unique number assigned to each smoke detector 100, information indicating the remaining charge of the battery 121, temperature information from a temperature sensor provided in the CPU of the control unit 141, and signal information from the light-receiving element 152. When there is no fire, the signal from the light-receiving element 152 is below a predetermined threshold.

[0041] The control unit 141 transmits periodic information from the transmission unit 142 to an external receiver. Specifically, a signal is transmitted from the output antenna 143 to a receiver arranged on the production line. At this time, the third case 150 functions as a ground, thereby improving the antenna efficiency of the output antenna 143. Furthermore, the straight section keeps the output antenna 143 away from the third case 150, making it difficult for electromagnetic coupling to occur between the third case 150 and the output antenna 143. This also improves the efficiency of the output antenna 143.

[0042] When a fire occurs, smoke rises inside the control box 200. The rising smoke moves about 2 centimeters away from the top plate 201 and flows along the top plate 201. If a fan 203 is provided in the control box 200, the smoke is subjected to the suction force of the fan 203 and flows along the top plate 201 toward the fan 203.

[0043] Smoke detector 100 detects smoke when smoke flows into detection space 132. When detection space 132 is filled with smoke, light from light-emitting element 151 is struck by the smoke and scattered. The scattered light from the smoke is detected by light-receiving element 152, which is activated at the same time as light-emitting element 151, and light-receiving element 152 outputs a weak detection signal of about a few nanoamperes. This detection signal is amplified by an amplifier circuit and input to control unit 141. This signal allows smoke detector 100 to detect the occurrence of a fire.

[0044] In this case, if electromagnetic waves are applied to the light receiving element 152 or the amplifier circuit, this may cause electromagnetic noise, which may cause the smoke detector 100 to react incorrectly. However, in the smoke detector 100 of this example, a shielded space is formed by the third case 150, which is made of a conductive resin material and includes the board assembly 140. The light receiving element 152 and the amplifier circuit are disposed within this shielded space. Therefore, the light receiving element 152 and the amplifier circuit are less susceptible to disturbances caused by electromagnetic waves.

[0045] When the signal from the light receiving element 152 exceeds a predetermined threshold, the control unit 141 determines that a fire has occurred and transmits an alarm signal from the transmission unit 142. At the same time, it turns on the alarm light 146. However, the alarm signal may be made redundant to prevent the transmission of erroneous information. For example, since the presence or absence of smoke is periodically determined, it may be determined that an alarm signal has been received when a signal exceeding the threshold is received three or more times in succession. Furthermore, the alarm signal may be determined in combination with a signal from a temperature sensor provided in the CPU of the control unit 141.

[0046] The operation of the smoke detector 100 has been explained above. In this example, smoke is easily guided into the detection space 132 of the smoke detector 100, so the air flow from upstream to downstream will be explained in detail below using Figure 14.

[0047] The control box 200 in which the smoke detector 100 of this example is installed has a smaller volume than a building such as a factory, and is therefore easily filled with smoke. Smoke rises close to the top plate 201, but the air stagnates directly below the top plate 201. As a result, the main flow of smoke occurs at a position approximately 2 centimeters away from the top plate 201. This is the position where the other axial end of the ventilation window 131 of the smoke detector 100 opens.

[0048] In this example, detection space 132 is formed near bottom 134 of second case 130. In the axial direction, it is separated from first case 120, including base 110 fixed to top plate 201. The axial length of smoke detector 100 in this example is about 50 millimeters, which is somewhat separated from the position of the main stream of smoke. However, in smoke detector 100 in this example, ventilation window 131 opens at the position of the main stream of smoke, so smoke can be effectively guided into detection space 132.

[0049] When a fan 203 is installed in the control box 200, the fan 203 generates a unidirectional air flow. Smoke flows into the smoke detector 100 through a ventilation window 131 that opens upstream of the air flow, but encounters a large flow resistance due to the insect screen 160. In this example, to reduce the flow resistance of the insect screen 160, the area of ​​the ventilation window 131 is made as large as possible. That is, the ventilation window 131 extends from near the bottom 134 of the second case 130 at one axial end to a portion facing the first case 120 at the other axial end. The insect screen 160 is then placed at the opening of the ventilation window 131, thereby increasing the opening area of ​​the ventilation window 131 and the area of ​​the air flow passing through the insect screen 160. Specifically, second case insect screen holding groove 138 is formed at approximately the same position as one axial end of ventilation window 131, so that one axial end of ventilation window 131 and one axial end of insect screen 160 are approximately aligned. At the other axial end, ventilation window 131 extends further toward the other end than insect screen 160. However, first case insect screen holding groove 123, which holds the other end of insect screen 160, is also formed in first case 120. As a result, the axial length of insect screen 160 is longer than that of detection space 132.

[0050] For example, if the axial length of the portion corresponding to detection space 132 is approximately 11 millimeters, then the axial length of ventilation window 131 will be approximately 11 millimeters if the opening of ventilation window 131 is aligned with detection space 132. In this example, the axial length of smoke detector 100 is approximately 50 millimeters, but even when considering base 110 of first case 120 and bottom 134 of second case 130, ventilation window 131 in this example can have an axial length of approximately 30 millimeters. Therefore, ventilation window 131 in this example has an opening area through which air passes that is 2.7 times larger than in an example in which only the portion corresponding to detection space 132 is open. However, the air guide effect can be sufficiently achieved even if the opening area is not increased by 2.7 times. For example, even if the axial length of the ventilation window 131 is reduced to 15 mm, half of the 30 mm in this example, and the opening area is increased by 1.4 times, the air flow velocity required to pass the same amount of air can be reduced to 0.73 times.

[0051] For example, suppose the flow velocity required for a given amount of air to flow through the ventilation window 131 is 1 meter per second. If the insect screen 160 has a 60-mesh mesh and the mesh gap is approximately 0.2 millimeters, the pressure loss when air flows at a flow velocity of 1 meter per second is 6.3 Pascals. On the other hand, even if the insect screen 160 has the same mesh, if the flow velocity is reduced to 0.73 meters per second, the pressure loss decreases to 3.4 Pascals. In this way, the pressure loss decreases by 0.55 times. Consider a case where the axial length of the ventilation window 131 is as short as 11 millimeters and the air cannot pass through the insect screen 160 when the air flow velocity is 1 meter per second. Even in this case, air can be guided to the detection space 132 simply by increasing the axial length by 1.4 times, to 15 millimeters. In this example, the ventilation window 131 is 30 millimeters, so the effect of guiding air to the detection space 132 is even more pronounced.

[0052] In this way, ventilation window 131 in this example has an increased axial length and an increased opening area, making it easier to introduce smoke into detection space 132. In addition, as described above, ventilation window 131 in this example is also open at a position approximately 20 mm away from top panel 201, which corresponds to the mainstream of the air flow. This also makes it easier to introduce smoke from ventilation window 131 into detection space 132.

[0053] Furthermore, air that flows into ventilation window 131 from near top panel 201 faces tapered portion 125 of first case 120. Therefore, air can easily flow along tapered portion 125 toward detection space 132. In addition, as shown in FIGS. 11 and 12 , the outer periphery of first case 120 and the outer periphery of third case 150 are smoothly connected. Therefore, air that flows along tapered portion 125 of first case 120 continues to flow along the outer periphery of third case 150. Moreover, the outer periphery of third case 150 is hemispherical, and its center corresponds to detection space 132. This outer periphery shape of third case 150 also makes it easy for air to flow into detection space 132.

[0054] In addition to the above-described structure, smoke detector 100 of this example has air guide sections formed on the outer periphery of first case 120, the outer periphery of third case 150, and inside second case 130. First case air guide section second portion 1242, third case air guide section 155, and second case air guide section 137 are continuous and integrally formed. First case air guide section first portion 1241 is formed on the other axial end side of ventilation window 131. Therefore, air flowing in from ventilation window 131 is also guided toward insect screen 160 by first case air guide section first portion 1241. Air passing through insect screen 160 is guided by first case air guide section second portion 1242, third case air guide section 155, and second case air guide section 137 to detection space 132. Guidance by the air guide sections stabilizes the air flow. This effect also makes it easier for smoke to flow into the detection space 132.

[0055] The above describes the airflow from ventilation window 131 toward detection space 132, but the same applies to the airflow from detection space 132 toward ventilation window 131 on the downstream side of the air flow. Figure 14 shows that the flow velocity decreases and the static pressure of the air increases on the upstream side of the air flow. As described above, pressure loss occurs when the air passes through insect screen 160, but in this example, the static pressure at ventilation window 131 on the upstream side of the air flow exceeds the pressure loss, so the air passes through insect screen 160 and flows into the air guidance section.

[0056] Conversely, negative pressure is generated at the ventilation window 131 downstream of the air flow. This negative pressure causes air in the detection space 132 to be sucked out to the ventilation window 131 downstream of the air flow. Furthermore, in this example, one axial end of the ventilation window 131 is located at a hemispherical bottom 134. Therefore, one axial end of the ventilation window 131 is bent radially inward. This bending makes it easier for negative pressure to be generated at the ventilation window 131 downstream of the air flow. In particular, because this bending is located at one axial end and close to the detection space 132, it is easier to draw air from the detection space 132 downstream of the air flow.

[0057] In addition to the air flow from the ventilation window 131 toward the detection space 132, there is also an air flow that flows around the outer periphery of the second case 130 along the tubular portion 135 of the second case 130. The flow velocity of this air flowing around the outer periphery of the second case 130 increases at a position downstream of the air flow. At the position where this flow velocity increases, the insect screen holding portion 1391 formed on the inner circumferential surface of the crosspiece 139 also contributes to stabilizing the air flow. This is because the insect screen holding portion 1391 has a shape that protrudes toward the insect screen 160, and therefore has the effect of suppressing the air flow from being drawn in around the inner periphery of the crosspiece 139. By forming the insect screen holding portion 1391, the negative pressure at the ventilation window 131 downstream of the air flow is stabilized, making it easier to draw air from the detection space 132 downstream.

[0058] Making it easier to draw air downstream of the air flow means making it easier for air to flow into the detection space 132 from the upstream side of the air flow. To improve the air flow, first, increasing the area of ​​the ventilation window 131 has the effect of reducing the flow velocity required for the air to pass through the insect screen 160. Another effect is improving the air flow by guiding the air flow with the first case air guide section 124 (first case air guide section first portion 1241 and first case air guide section second portion 1242), the second case air guide section 137, and the third case air guide section 155. These effects are not limited to the upstream side of the air flow described above. A similarly favorable air flow can be achieved downstream of the air flow. Combined with these effects downstream of the air flow, the smoke detector 100 of this example makes it easier to introduce smoke into the detection space 132.

[0059] The smoke detector 100 of this example is also characterized by the positions of the warning light 146 and the insect screen 160, so next, the characteristics of the warning light 146 will be described. As shown in FIG. 12 , the warning light 146 is disposed on the inner periphery of the insect screen 160, and when lit, it emits red light toward the insect screen 160. Therefore, when the warning light 146 is lit, the light is reflected by the insect screen 160 and spreads over a wider range (wide angle). When the smoke detector 100 is disposed inside the control box 200, the light from the warning light 146 will leak to the outside through gaps in the fan 203, door, etc. Therefore, by spreading the light from the warning light 146 over a wide angle, it becomes easier for the light to leak outside the control box 200, improving visibility.

[0060] Next, a modified example of the smoke detector 100 of this embodiment will be described. In the above example, the bottom 134 of the second case 130 is hemispherical. This is a desirable shape because it makes it easier to generate negative pressure downstream of the air flow. However, the negative pressure downstream of the air flow can be utilized if the bottom 134 is bent and one axial end of the ventilation window 131 is located at the bent portion. Therefore, the shape of the bottom 134 is not limited to a hemispherical shape, and it may also be tapered in the circumferential direction.

[0061] In the above example, the detection elements were light-emitting element 151 and light-receiving element 152, so it was necessary to prevent external light from entering detection space 132. For this reason, second case air guide section 137 and third case air guide section 155 were provided with a light-blocking function as labyrinth walls. However, if the detection elements were gas sensors, second case air guide section 137 and third case air guide section 155 would not need to have a light-blocking function. The essential function of first case air guide section 124, second case air guide section 137, and third case air guide section 155 is to straighten the air flow between ventilation window 131 and detection space 132.

[0062] In the above example, the smoke detector 100 was equipped with the insect screen 160. In the above example, the configuration of the first case insect screen holding groove 123, the second case insect screen holding groove 138, the insect screen holding portion 1391, etc. was adopted on the assumption that the insect screen 160 would be present. In addition, the position of the warning light 146 was determined on the assumption that the insect screen 160 would be present. However, if the detection element is a gas sensor, the insect screen 160 is not necessarily required.

[0063] In the above example, the smoke detector 100 is disposed in a closed space such as the control box 200, and therefore does not include a speaker. However, a speaker can be used. If a speaker is provided, the control unit 141 may activate the speaker along with the flashing of the alarm light 146. This allows the surrounding area to be notified of a fire. Furthermore, in order to achieve a compact and lightweight design, the smoke detector 100 of this example only includes a transmitter 142 that transmits signals, and does not include a receiver. However, a receiving function can be provided. If the smoke detector 100 includes a receiving function, it may be configured to receive alarm signals from other nearby smoke detectors 100. In this case, upon receiving an alarm signal from another smoke detector 100, the speaker may be activated or the alarm LED 146 may be flashed. Furthermore, the receiving function may be used to receive signals from an external management server. For example, the smoke detector 100 may receive a signal to change the communication channel or the number of bands, thereby changing its settings. In this case, the setting change is performed by the control unit 141.

[0064] In the above example, the control unit 141 determines whether a fire has occurred and transmits an alarm signal when there is a risk of a fire. This is a desirable example because the alarm signal can be determined near the signal from the light-receiving element 152. However, it is also possible for the smoke detector 100 to always only transmit signals at predetermined times. In this case, the signals from each smoke detector 100 are received by a receiver located on the production line and sent to a management server located at a location separate from the production line via a communication line such as the Internet and / or an intranet cloud system. The management server then determines whether a fire has occurred. If the smoke detector 100 does not determine whether an alarm signal should be generated, the alarm light 146 is also unnecessary.

[0065] In the above-described embodiment, an example was described in which the detector of the present disclosure was used as a smoke detector 100 in a factory. This is a desirable application of the detector of the present disclosure, as it requires the rapid inflow of smoke. However, the smoke detector 100 can also be used for other purposes. It can be used not only in factories but also for environmental monitoring in remote locations. For example, it can be used in substations, inside ship or truck containers, warehouses, and cubicles housing solar power storage batteries. Depending on the usage situation, the base 110 may be screwed to the ceiling of a building. Furthermore, depending on the usage situation, the base 110 may be fixed to the wall of a building. Therefore, in the present disclosure, "acting as a smoke detector 100" means that it can be used widely as a smoke detection device, not limited to use in factories.

[0066] In the above-described embodiment, an example was described in which the detector of the present disclosure is used as a smoke detector 100. The smoke detector 100 is a desirable example of a detector. However, the detector element is not limited to the light-emitting element 151 and the light-receiving element 152. Other detector elements that perform equipment sensing of odors, vibrations, sounds, etc. may also be used. For example, a detector element that detects carbon dioxide or odors may be used to detect the smell of burning grease in a motor installed on a production line, thereby detecting a malfunction of the production line. Furthermore, when an abnormality occurs in a motor installed on a production line, vibrations increase or a loud abnormal noise is generated. By detecting these vibrations or abnormal noises with a detector element, it is possible to detect malfunctions in the production line in advance.

[0067] The sensor of the present disclosure can be used in a wide range of applications as a wireless IOT (Internet of Things) sensor, including home appliances and wearable devices.

[0068] Furthermore, the sizes and materials in the above-described embodiments are merely examples. For example, while the third case 150 is injection molded from a conductive resin material in the above-described embodiment, it may be formed from a conductive metal material. Examples of metal materials include copper, aluminum, and iron. Alternatively, the third case 150 may be formed from a non-conductive resin material, and a conductive metal may be plated or spray-coated on the surface. Furthermore, while the insect screen 160 is made of a non-conductive stainless steel wire material in the above-described embodiment, it may also be made from a non-conductive resin material.

[0069] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0070] (Technical thought 1) a first case (120) attached to the detection site; a second case (130) having an axially extending cylindrical portion (135), a bottom portion (134) formed at one axial end of the cylindrical portion, and an opening portion (136) formed at the other axial end of the cylindrical portion; a third case (150) that holds a detection element, a control unit (141) that controls the detection element, and a transmission unit (142) that transmits a signal detected by the detection element to the outside; the first case is held inside the second case on the opening side of the second case, the third case is held inside the second case at one end side of the first case in the axial direction, the second case forms a detection space for detection by the detection element on one end side of the third case in the axial direction, A plurality of ventilation windows (131) extending in the axial direction are formed in the circumferential direction in the cylindrical portion of the second case, and one end side of the ventilation windows in the axial direction corresponds to the position of the detection space, and the other end side of the ventilation windows in the axial direction corresponds to the position of the first case, The first case, the second case, and the third case are formed with air guide sections (124, 137, 155) that guide air upstream in the air flow from the ventilation window to the detection space and guide air from the detection space to the ventilation window downstream in the air flow. sensor.

[0071] (Technical thought 2) The air guide sections formed in the second case and the third case have a light blocking function that blocks external light from entering the detection space through the ventilation window. A detector according to technical idea 1.

[0072] (Technical Thought 3) an insect screen (160) for preventing foreign matter from entering the detection space through the ventilation window is disposed on the radially inner side of the cylindrical portion of the second case; One axial end of this insect screen is held by the second case, and the other axial end is held by the first case. A detector according to technical idea 1 or technical idea 2.

[0073] (Technical Thought 4) an insect screen is disposed on the radially inner side of the cylindrical portion of the second case to prevent foreign matter from entering the detection space through the ventilation window; The air guide section of the first case includes a first case air guide section first part (1241) arranged on the radially outer side of the insect screen and a first case air guide section second part (1242) arranged on the radially inner side of the insect screen. A detector according to technical idea 1 or technical idea 2.

[0074] (Technical Thought 5) The first case air guide section second portion of the first case, the air guide section of the second case, and the air guide section of the third case are continuously formed into an integrated shape. A detector according to technical idea 4. (Technical Thought 6) An insect screen holding portion (1391) protruding toward the insect screen is formed on the inner peripheral surface of a sash portion (139) between the ventilation windows in the cylindrical portion of the second case. A detector according to any one of technical ideas 3 to 5.

[0075] (Technical Thought 7) The third case further holds an indicator light (146) that lights up to indicate that the detector element has detected something, When turned on, the warning light irradiates light from the inner periphery of the insect screen toward the insect screen. A detector according to any one of technical ideas 3 to 6.

[0076] (Technical Thought 8) One axial end portion of the ventilation window is formed in the bottom portion of the second case, and the bottom portion is bent radially inward at a portion where the one axial end of the ventilation window is formed. A detector according to any one of technical ideas 1 to 7. [Explanation of symbols]

[0077] 100 smoke detector 120 Case 1 124 First case air guide section 130 Case 2 131 Ventilation window 137 Second case air guide section 150 Case 3 155 Third case air guide section 151 Light-emitting element 152 Photodetector

Claims

1. a first case (120) attached to the detection site; a second case (130) having an axially extending cylindrical portion (135), a bottom portion (134) formed at one axial end of the cylindrical portion, and an opening portion (136) formed at the other axial end of the cylindrical portion; a third case (150) for holding a detection element, a control unit (141) for controlling the detection element, and a transmission unit (142) for transmitting a signal detected by the detection element to the outside; the first case is held inside the second case on the opening side of the second case, the third case is held inside the second case at one end side of the first case in the axial direction, the second case forms a detection space for detection by the detection element on one end side of the third case in the axial direction, A plurality of ventilation windows (131) extending in the axial direction are formed in the circumferential direction in the cylindrical portion of the second case, and one axial end side of the ventilation windows corresponds to the position of the detection space and the other axial end side corresponds to the position of the first case, The first case, the second case, and the third case are formed with air guide sections (124, 137, 155) that guide air upstream in the air flow from the ventilation window to the detection space and guide air from the detection space to the ventilation window downstream in the air flow. sensor.

2. The air guide sections formed in the second case and the third case have a light blocking function that blocks external light from entering the detection space through the ventilation window. The detector of claim 1 .

3. an insect screen (160) for preventing foreign matter from entering the detection space through the ventilation window is disposed on the radially inner side of the cylindrical portion of the second case; One axial end of the insect screen is held by the second case, and the other axial end is held by the first case. The detector of claim 1 .

4. an insect screen is disposed on a radially inner side of the cylindrical portion of the second case to prevent foreign matter from entering the detection space through the ventilation window; The air guide section of the first case includes a first case air guide section first part (1241) arranged on the radially outer side of the insect screen and a first case air guide section second part (1242) arranged on the radially inner side of the insect screen. The detector of claim 1 .

5. The first case air guide portion second portion of the first case, the air guide portion of the second case, and the air guide portion of the third case are continuously formed into an integrated shape.

5. The detector of claim 4.

6. An insect screen holding portion (1391) protruding toward the insect screen is formed on the inner peripheral surface of a sash portion (139) between the ventilation windows in the cylindrical portion of the second case. A detector according to claim 3 or 4.

7. The third case further holds an indicator light (146) that lights up to indicate that the detector element has detected something, When turned on, the warning light irradiates light from the inner periphery of the insect screen toward the insect screen. A detector according to claim 3 or 4.

8. One axial end portion of the ventilation window is formed in the bottom portion of the second case, and the bottom portion is bent radially inward at a portion where the one axial end of the ventilation window is formed. The detector of claim 1 .

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