JP6127280B1 - Particle detection sensor - Google Patents

Abstract

Turbulent flow in a detection region of a photoelectric particle sensor is suppressed. A particle detection sensor 1 according to the present invention is provided in a housing 10 having a housing inflow portion 101 through which outside air flows, a housing outflow portion 102 through which outside air flows out, and a housing 10. In the detection area DA that is an area where the light projecting area of the light projecting element 121 and the light receiving target area of the light receiving element 131 overlap, the particles 2 are received by receiving the scattered light of the light projecting element 121 by the particles 2 contained in the outside air. An outer shell 63 that is installed around the housing 10 and has at least one outside air inflow portion 631 through which outside air flows, and at least one outside air outflow portion 632 through which outside air flows out, and an outside air inflow portion 631. Alternatively, it includes a blower mechanism 66 provided in the vicinity of one of the outside air outflow portions 632, a first flow path 61, and a second flow path 62, and the fluid resistance of the first flow path 61 is the second. Of the flow path 62 Larger than the body resistance. [Selection] Figure 1

Description

  The present invention relates to a particle detection sensor.

  2. Description of the Related Art Conventionally, particle detection sensors that detect particles floating in the atmosphere are known. The change in the amount of light received by detecting changes in the amount of light received when particles floating in the atmosphere are taken into the sensor along with the air current and the particles cross the detection area of the light emitting element and light receiving element provided inside the sensor. To detect the size and number of particles.

  Currently, photoelectric particle detection sensors are becoming smaller in size as they are incorporated into consumer equipment such as air conditioners and air purifiers. Moreover, in order to prevent disturbance light irradiation to the light receiving element by size reduction, the optical trap structure is incorporated in the inside of a sensor (patent document 1).

JP 2013-195261 A

  In the particle detection sensor that counts the number of particles, it is desirable that the airflow that takes particles floating in the atmosphere into the detection region inside the sensor is a laminar flow. However, since the flow path width through which the airflow flows becomes narrow due to the downsizing of the sensor and the flow path shape is complicated due to the built-in optical trap structure, There is a problem that the flow velocity of the particles becomes faster than necessary, turbulence is likely to occur in the detection region, and the particle detection accuracy decreases.

  The present invention has been made to solve such a problem, and an object of the present invention is to suppress the occurrence of turbulent flow in a detection region and prevent a decrease in particle detection accuracy.

In order to achieve the above object, one aspect of the particle detection sensor according to the present invention includes: a housing having a housing inflow portion through which outside air flows; a housing outflow portion through which the outside air flows out; The particle is obtained by receiving the scattered light of the light projecting element by the particles contained in the outside air in a detection area that is an area where the light projecting area of the light projecting element and the light receiving target area of the light receiving element overlap. a sensor unit for detecting the at least one external air inlet before Kigaiki flows, and a shell having at least one external air outlet portion and the ambient air flows out, the shell is provided with the housing outflow section A space is provided between the outside air outflow portion and the housing is installed around the casing. A blower mechanism is further provided downstream of the outside air outflow portion, and a part of the outside air flows from the outside air inflow portion to the housing. Inside the housing through the body inflow part The first flow path that is attracted and passes through the detection region, is discharged to the outside air outflow portion through the housing outflow portion, and a part of the outside air is attracted from the outside air inflow portion by the air blowing mechanism, and the housing A second flow path that passes between the outside of the body and the inside of the outer shell and is discharged to the outside air outflow portion. The fluid resistance of the first flow path is the fluid resistance of the second flow path. much larger than the said at least part of the space between the housing outlet portion and the outside-air discharge unit, wherein the first flow path and the second flow path shares the channel, the housing An airflow guiding wall is provided in the vicinity of the body outflow portion to prevent the outside air passing through the second flow path from flowing in from the housing outflow portion .

  According to the present invention, it is possible to suppress turbulent flow in the detection region and prevent a decrease in particle detection accuracy.

FIG. 1 is a schematic perspective view of a particle detection sensor according to Embodiment 1 of the present invention. FIG. 2 is a schematic perspective view of the housing according to Embodiment 1 of the present invention. FIG. 3 is an exploded perspective view of the housing according to Embodiment 1 of the present invention. FIG. 4 is a six-sided view of the housing according to Embodiment 1 of the present invention. FIG. 5 is a cross-sectional view showing the inside of the housing according to Embodiment 1 of the present invention. FIG. 6 is a cross-sectional view of the outer shell according to the first embodiment of the present invention. FIG. 7 is a longitudinal sectional view of the particle detection sensor according to Embodiment 1 of the present invention. FIG. 8 is a cross-sectional view of an outer shell according to Modification 1 of the present invention. FIG. 9 is a longitudinal sectional view of a particle detection sensor according to Modification 2 of the present invention. FIG. 10 is a longitudinal sectional view of a particle detection sensor according to Modification 3 of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that each of the embodiments described below shows a preferred specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps (steps) and order of steps, and the like shown in the following embodiments are examples and limit the present invention. It is not the purpose to do. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

  Each figure is a schematic diagram and is not necessarily illustrated strictly. Moreover, in each figure, the same code | symbol is attached | subjected to the substantially same structure, The overlapping description is abbreviate | omitted or simplified.

(Embodiment 1)
[Particle detection sensor]
First, the outline | summary of the particle | grain detection sensor concerning this Embodiment is demonstrated using FIGS.

  The particle detection sensor 1 has a flat and substantially rectangular parallelepiped shape shown in FIG. 1, and the directions along two sides orthogonal to each other are taken as an X-axis direction and a Y-axis direction, respectively. Moreover, let the thickness direction of the particle | grain detection sensor 1 be a Z-axis direction. In the present embodiment, the particle detection sensor 1 has a size within a range of, for example, X: 64 mm × Y: 47 mm × Z: 34 mm.

  As illustrated in FIGS. 1 and 5, the particle detection sensor 1 is a photoelectric particle detection sensor including a housing 10 and an optical system 20 disposed inside the housing 10 inside an outer shell 63. Specifically, in the particle detection sensor 1, the optical system 20 irradiates the detection area DA in the housing 10 with light, and receives light scattered by the particles 2 (aerosol) passing through the detection area DA. The presence or absence of particles 2 is detected. Further, the particle detection sensor 1 is not limited to the presence or absence of the particles 2 and may detect the number and size of the particles 2. The particles 2 to be detected by the particle detection sensor 1 are fine particles such as fine dust, pollen, smoke, and PM2.5, for example.

  The outer shell 63 is a structure that surrounds the housing 10. In the present embodiment, the outer shell 63 has an outside air inflow portion 631 and an outside air outflow portion 632. The outside air including the particles 2 flows into the particle detection sensor 1 from the outside air inflow portion 631, and at least a part thereof flows out of the outside air outflow portion 632 through the detection area DA in the housing 10. The detailed configuration of the outer shell 63 will be described later.

The housing 10 is a housing (case) that covers the optical system 20 and the detection area DA. The housing 10 is
The optical system 20 and the detection area DA are covered and the relative positions of the optical system 20 and the detection area DA are fixed so that external light is not irradiated onto the optical system 20 and the detection area DA.

  The housing 10 includes a housing inflow portion 101 for allowing the particles 2 to flow into the interior, and a housing outflow portion 102 for allowing the particles 2 that have flowed into the interior to flow out. In the present embodiment, as indicated by the thick dotted arrow in FIG. 5, the particles 2 flow from the housing inflow portion 101, pass through the inside of the housing 10 (for example, the detection area DA), and the housing outflow portion. Out of 102. A detailed configuration of the housing 10 will be described later.

  The optical system 20 optically detects the particles 2 that flow into the housing 10 through the housing inflow portion 101 and pass through the detection area DA. In the present embodiment, the optical system 20 includes a light projecting system 120 and a light receiving system 130 that are arranged so that their optical axes (the optical axis P and the optical axis Q) intersect the detection area DA. The particle 2 passing through the DA is detected by the light receiving system 130 using the light output from the light projecting system 120. The light projecting system 120 includes a light projecting element 121 and a light projecting lens 122. The light receiving system 130 includes a light receiving element 131 and a light receiving lens 132. The detailed configuration of the optical system 20 will be described later.

  The detection area DA (light scattering part) is an aerosol detection area (aerosol measurement part) that is an area for detecting the particles 2 contained in the gas to be measured. The detection area DA is, for example, φ2 mm. The gas to be measured flows from the housing inflow portion 101 of the housing 10, is guided to the detection area DA, and then flows out from the housing outflow portion 102.

  As shown in FIGS. 2, 3, and 5, the particle detection sensor 1 further includes an optical trap 40, a circuit board 70, a connector 80, a first shield cover 90, and a second shield cover 91. .

  In the present embodiment, the optical trap 40 traps light that is output from the light projecting system 120 and takes the detection area DA, and second light that traps light that is not trapped in the first optical trap 41. It consists of an optical trap 42. The first light trap 41 is provided at a position facing the light projecting system 120 via the detection area DA. The second optical trap 42 is provided at a position facing the light receiving system 130 via the detection area DA. The second optical trap 42 has, for example, a labyrinth structure in which a plurality of wedge-shaped protrusions 115 are provided.

  The circuit board 70 is a printed wiring board on which a control circuit for the particle detection sensor 1 is formed. The control circuit controls, for example, the output of light by the light projecting system 120 and the processing of an electrical signal based on the optical signal received by the light receiving system 130. For example, the control circuit detects the presence / absence, size, and number of particles 2 and outputs the detection result to the outside via the connector 80.

  The circuit board 70 is, for example, a rectangular flat plate, and the housing 10 is fixed to one main surface (front surface). One or a plurality of circuit elements (circuit components) constituting the control circuit are mounted on the other main surface (back surface). The electrode terminals of the light projecting element 121 and the light receiving element 131 penetrate the back cover 110 (details will be described later) of the housing 10 and the circuit board 70 and are soldered to the back surface of the circuit board 70. Thereby, each of the light projecting element 121 and the light receiving element is electrically connected to the control circuit, and the operation is controlled by the control circuit.

  The plurality of circuit elements include, for example, a resistor, a capacitor, a coil, a diode, or a transistor. As shown in FIG. 5, the electrolytic capacitor 71, which is one of the plurality of circuit elements, is provided on the surface of the circuit board 70 and is disposed in the housing 10.

The connector 80 is a connector for connecting the control circuit (circuit board 70) of the particle detection sensor 1 to an external control circuit or a power supply circuit. The connector 80 is mounted on the back surface of the circuit board 70. For example, the particle detection sensor 1 operates by supplying electric power from the outside via the connector 80.

  The first shield cover 90 is a metal cover provided to protect the control circuit from external noise. The first shield cover 90 is attached to the back side of the circuit board 70.

  The second shield cover 91 is a metal cover provided to protect the light receiving element 131 of the light receiving system 130 from external noise. As shown in FIGS. 4A, 4D, and 4E, the second shield cover 91 is a part of the front, top, and left side of the housing 10, and the light receiving element 131 is disposed therein. Covers the part that was made.

  The first shield cover 90 and the second shield cover 91 are made of tin plate that can be easily connected by soldering, for example.

  Below, each component with which the particle | grain detection sensor 1 is provided is demonstrated in detail.

[Case]
The housing 10 is provided with a sensor section and a light trap 40 each including a detection area DA and an optical system 20. In the present embodiment, the housing 10 is composed of two members, a front cover 100 and a back cover 110.

  The housing 10 has a light shielding property. For example, the housing 10 is black at least on the inner surface so as to absorb stray light.

  Here, the stray light is light other than the scattered light by the particles 2. Specifically, the stray light is not scattered by the particles 2 in the detection area DA out of the light output from the light projecting system 120, and the inside of the housing 10. It is a traveling light.

  The housing 10 is formed, for example, by injection molding using a resin material such as ABS resin. Specifically, each of the front cover 100 and the back cover 110 is formed by injection molding using a resin material, and then combined with each other to form the housing 10. At this time, for example, by using a resin material to which a black pigment or dye is added, the inner surface of the housing 10 can be made a black surface.

  The housing 10 is a flat polyhedron, as shown in FIGS. 2 and 3, and includes a front surface portion 10a, a back surface portion 10b, a lower surface portion 10c, an upper surface portion 10d, a left side surface portion 10e, and a right side surface portion 10f. Have Specifically, as illustrated in FIG. 4A, the housing 10 has a prismatic shape having a bottom surface of a substantially heptagon in which the upper right corner and the upper left corner of the four corners of the rectangle are slanted.

  The front surface portion 10a, the back surface portion 10b, the lower surface portion 10c, the upper surface portion 10d, the left side surface portion 10e, and the right side surface portion 10f form a front surface (front surface), a back surface, a lower surface, an upper surface, a left side surface, and a right side surface, respectively. The front part 10 a is the bottom of the front cover 100, and the back part 10 b is the bottom of the back cover 110. The lower surface portion 10c, the upper surface portion 10d, the left side surface portion 10e, and the right side surface portion 10f are formed by combining the side periphery of the front cover 100 and the side periphery of the back cover 110.

In addition, the shape of the housing | casing 10 is an example, Comprising: It does not restrict to this. For example, the housing 10 may be a rectangular parallelepiped having a rectangular bottom surface (front surface portion 10a and back surface portion 10b), or a circular cylinder having a circular bottom surface.

  As shown in FIG. 2, a housing inflow portion 101 and a housing outflow portion 102 are provided on the outer wall of the housing 10. Specifically, a housing inflow portion 101 and a housing outflow portion 102 are provided on the front surface portion 10 a of the housing 10.

  The housing inflow portion 101 is an opening having a predetermined shape provided on the outer wall of the housing 10, and the gas containing the particles 2 flows into the housing 10 through the opening. The case inflow portion 101 is, for example, a substantially rectangular opening of 5.5 mm × 12 mm, but the shape of the case inflow portion 101 is not limited to this. For example, the casing inflow portion 101 may be an opening such as a circle or an ellipse.

  In the present embodiment, as shown in FIG. 5, the housing inflow portion 101 is not provided directly below the detection area DA, but is provided in the lower corner of the front cover 100. This makes it difficult for external light entering from the housing inflow portion 101 to be irradiated to the detection area DA, and to prevent the light from entering the light receiving element 131 as stray light.

  The case outflow portion 102 is an opening having a predetermined shape provided on the outer wall of the case 10, and the gas containing the particles 2 flows out of the case 10 through the opening. The case outflow portion 102 is, for example, a substantially rectangular opening of 5 mm × 12 mm, but the shape of the case outflow portion 102 is not limited to this. For example, the housing outflow portion 102 may be an opening such as a circle or an ellipse. The size of the housing outflow portion 102 is substantially the same as that of the housing inflow portion 101, for example.

  In addition, although the housing | casing inflow part 101 and the housing | casing outflow part 102 were provided in the front part 10a of the housing | casing 10, it is not restricted to this. For example, the housing inflow portion 101 may be provided on the back surface portion 10b, the bottom surface portion 10c, the left side surface portion 10e, or the right side surface portion 10f of the housing 10. Further, the housing outflow portion 102 may be provided on the back surface portion 10b, the top surface portion 10d, the right side surface portion 10e, or the left side surface portion 10f of the housing 10.

  The housing 10 is provided with an internal structure for configuring the optical trap 40. Specifically, the back cover 110 includes a first light reflecting wall 111, a second light reflecting wall 112, a third light reflecting wall 113, a fourth light reflecting wall 114, and a plurality of wedge-shaped protrusions 115 standing from the inner surface. Have. The first light reflecting wall 111 and the second light reflecting wall 112 form a first light trap 41. The third light reflecting wall 113, the fourth light reflecting wall 114, and the plurality of wedge-shaped protrusions 115 form the second light trap 42.

  The housing 10 is further provided with a cleaning window 108 on the front surface portion 10a. Specifically, the cleaning window 108 is a trapezoidal through hole provided in the center of the front cover 100. The cleaning window 108 is provided to remove dirt or dust attached to the inside of the light projecting lens 122, the light receiving lens 132, and the housing 10. For example, the inside of the housing 10 can be cleaned by inserting a cotton swab or the like through the cleaning window 108. When the particle detection sensor 1 is operated, the cleaning window 108 is covered with a cover member (not shown) so that external light is not irradiated onto the detection area DA through the cleaning window 108.

[Optical system]
The optical system 20 is disposed in the back cover 110 of the housing 10 and is housed inside the housing 10 by being sandwiched by the front cover 100. As shown in FIG. 5, the light projecting system 120 and the light receiving system 130 are arranged so that their optical axes (optical axis P and optical axis Q) intersect each other.

The light projecting system 120 outputs light so as to be focused on the detection area DA. The light projecting system 120 includes a light projecting element 121 and a light projecting lens 122.

  The light projecting element 121 is a light source (light emitting unit) that emits light of a predetermined wavelength, and is, for example, a solid light emitting element such as an LED (Light Emitting Diode) or a semiconductor laser. The optical axis of the light projecting element 121 coincides with the optical axis P of the light projecting system 120 and passes through the detection area DA, for example.

  As the light projecting element 121, a light emitting element that emits ultraviolet light, blue light, green light, red light, or infrared light can be used. In this case, the light projecting element 121 may be configured to emit a mixed wave having two or more wavelengths. In the present embodiment, a bullet-type LED that outputs light with a wavelength of 600 nm to 800 nm, for example, is used as the light projecting element 121 in view of the light scattering intensity by the particles 2.

  The light projecting lens 122 is disposed in front of the light projecting element 121 and is configured to travel light emitted from the light projecting element 121 toward the detection area DA. That is, the light emitted from the light projecting element 121 passes through the detection area DA via the light projecting lens 122. The particles 2 passing through the detection area DA scatter light from the light projecting element 121.

  The light projecting lens 122 is, for example, a condensing lens that focuses light emitted from the light projecting element 121 onto the detection area DA, and is, for example, a transparent resin lens such as polycarbonate (PC) or a glass lens. For example, the focus of the light projection lens 122 exists in the detection area DA.

  The light receiving system 130 receives light scattered from the light projecting system 120 by the particles 2 in the detection area DA. In FIG. 5, an example of a light path is indicated by a thick solid arrow. The light receiving system 130 includes a light receiving element 131 and a light receiving lens 132.

  The light receiving element 131 receives at least a part of light scattered from the light projecting element 121 by the particles 2 in the detection area DA. Specifically, the light receiving element 131 is a photoelectric conversion element that converts received light into an electrical signal, such as a photodiode, a photo IC diode, a phototransistor, or a photomultiplier tube. The optical axis of the light receiving element 131 coincides with the optical axis Q of the light receiving system 130 and passes, for example, the detection area DA.

  The light receiving lens 132 is disposed between the light receiving element 131 and the detection area DA, and is configured to collect light incident from the detection area DA side on the light receiving element 131. Specifically, the light receiving lens 132 is a condensing lens that condenses the scattered light from the particles 2 on the light receiving element 131 in the detection area DA, and is, for example, a transparent resin lens such as a PC or a glass lens. For example, the focal point of the light receiving lens 132 exists on the surface of the detection area DA and the light receiving element 131.

[Outside]
Inside the outer shell 63, a housing 10 and a second flow path (details will be described later) are provided. In the present embodiment, the outer shell 63 is composed of three members: an outer shell front cover 633, an outer shell rear cover 634, and an outer shell side cover 635.

  The outer shell 63 has a light shielding property and is formed by injection molding using a resin material such as ABS resin, for example. Specifically, each of the outer front cover 633, the outer rear cover 634, and the outer side cover 635 is formed by injection molding using a resin material, and then combined with each other to form the outer shell 63.

In the present embodiment, the outer shell 63 has a substantially rectangular parallelepiped shape as shown in FIG. 1, and includes a front surface portion 63a, a back surface portion 63b, a lower surface portion 63c, an upper surface portion 63d, a left side surface portion 63e, and a right side. And a surface portion 63f.

  The front surface portion 63 a is a bottom portion of the outer front surface cover 633, the back surface portion 63 b is a bottom portion of the outer surface back cover 634, and the right side surface portion 63 e is an outer surface side cover 635. The lower surface portion 63c, the upper surface portion 63d, and the left side surface portion 63f are formed by combining the side surface portion of the outer front cover 633 and the side surface portion of the outer rear cover 634.

  Note that the shape of the outer shell 63 is an example, and is not limited to this. For example, the outer shell 63 may be a prism having a substantially polygonal bottom surface (front surface portion 63a and back surface portion 63b), or a circular cylinder having a circular bottom surface.

  As shown in FIG. 1, the outer shell 63 is provided with an outside air inflow portion 631 and an outside air outflow portion 632. Specifically, the outside air inflow portion 631 is formed on the left side of the bottom of the outer front cover 633 of the outer shell 63 and in the vicinity of the housing inflow portion 101. For example, the outside air inflow portion 631 may be configured by a plurality of rectangular through holes. The outside air outflow portion 632 is provided in the outer side surface cover 635. In the present embodiment, an external air blowing mechanism is installed inside the outside air outflow portion 632. The external air blowing mechanism generates an air flow from the inside of the outer shell 63 toward the outside of the outer shell 63 at the outer air outflow portion 632, so that the gas including the particles 2 flows into the outer shell 63 and the inside of the housing 10 from the outer air inflow portion 631. .

  The outer back cover 634 has a notch 636. The notch 636 is installed in the vicinity of the connector 80 of the particle detection sensor 1. A power line or the like to which power is supplied from the outside is connected to the connector 80 through a notch 636.

[First channel, second channel]
As shown in FIG. 7, the first flow path 61 attracts a part of the outside air from the outside air inflow portion 631 to the inside of the housing 10 through the housing inflow portion 101, passes through the detection area DA, and flows out of the housing. This is a flow path for discharging from the outside air outflow part 632 to the outer shell 63 via the part 102. The flow of outside air in the first flow path is indicated by a dotted arrow.

  The second flow path 62 is a flow path that attracts part of the outside air from the outside air inflow portion 631 to the outer shell 63, passes through the outside of the housing 10, and is discharged from the outside air outflow portion 632 to the outside of the outer shell 63. In the present embodiment, the inner wall of the second flow path 62 is configured by the inner wall of the outer shell 63 and the outer wall of the front surface portion 10 a of the housing 10. In the present embodiment, the first flow path 61 is the second flow path between the outside air inflow portion 631 and the housing inflow portion 101 and between the housing outflow portion 102 and the outside air outflow portion 632. 62 and share a space. The flow of outside air in the second flow path is indicated by a one-dot broken line arrow.

  The flow path resistance of the first flow path 61 is configured to be larger than the flow path resistance of the second flow path 62. Here, the flow path resistance is a frictional force generated in the direction opposite to the flow between the inner wall of the flow path and the external air, which is generated when outside air that is a fluid passes through the flow path. When the channel is a straight pipe, the channel resistance P [Pa] is λ for the channel friction coefficient, L for the channel length [m], and ρ [kg / kg] for the outside air flowing through the channel. m3], flow velocity Va [m / s] in the flow path, and diameter d [m] of the flow path, can be expressed by the following equation.

  Here, the channel friction coefficient λ can be expressed by the following equation, for example, when the fluid flow in the channel is a laminar flow and the Reynolds number of the fluid is Re.

  Further, for example, when the flow of fluid flowing in the flow channel is turbulent, the flow channel friction coefficient λ can be expressed by the following equation, where Reynolds number of the fluid is Re.

  That is, the channel resistance increases as the channel length increases. The channel resistance increases as the channel becomes thinner.

  In the present embodiment, as shown in FIG. 7, the flow path resistance of the first flow path 61 is reduced by making the length of the second flow path 62 shorter than the length of the first flow path 61. The flow path resistance of the flow path 62 is larger. Further, for example, by making the effective cross-sectional area of the second flow path 62 larger than the effective cross-sectional area of the first flow path 61, the flow resistance of the first flow path 61 is reduced to the flow path of the second flow path 62. It may be larger than the resistance.

  In addition, the channel resistance includes elbow loss where energy loss occurs at the part where the channel bends, branching loss as energy loss at the branch, reduction loss where energy loss occurs when the channel shrinks, and channel expansion The flow path resistance increases as the flow path has more changes in the thickness of the bent section, branch, entrance / exit, or flow path. For this reason, it is preferable that the first flow path 61 has more bent portions, branches, and doorways than the second flow path 62. For example, in the present embodiment, as shown in FIGS. 5 and 7, after the first flow path 61 enters the outside air inflow part 631, the flow path in the case inflow part 101 and the case 10 is changed. There is a bend, and the case outflow portion 102 and the bend in the flow path between the case outflow portion 102 and the outside air outflow portion 632. On the other hand, the second flow path 62 travels straight between the outside air inflow portion 631 and the outside air outflow portion 632 almost without any bending of the flow path. In the present embodiment, the length of the first flow path 61 is longer than that of the second flow path 62.

  By configuring the flow path resistance of the first flow path 61 to be larger than the flow path resistance of the second flow path 62, the flow rate of the airflow flowing through the first flow path 61 including the detection area DA is limited. By slowing down the flow velocity, it is possible to suppress the occurrence of turbulent flow in the detection area DA and to prevent a decrease in particle detection accuracy.

[Airflow guide wall]
The airflow guiding wall 64 is installed in the vicinity of the housing outflow portion 102, and prevents outside air passing through the second flow path 62 from flowing in from the housing outflow portion 102. In the present embodiment, the airflow guiding wall 64 is in contact with the outer wall of the front surface portion 10 a of the housing 10 that constitutes a part of the inner wall of the second flow path 62. For example, the air flow guide wall 64 has one end 641 of both ends in a predetermined direction parallel to the front surface portion 10a of the housing 10 connected to the inner wall of the upper surface portion 63d of the outer shell 63, The other end 642 of both ends in a predetermined direction parallel to the front surface portion 10 a of the housing 10 of the guide wall 64 is not connected to the inner wall of the outer shell 63. With this configuration, the other end 6 connected to the inner wall of the upper surface 63d of the outer shell 63 is provided.
Backflow of outside air from the 42 side to the housing outflow portion 102 can be prevented. In addition, since the flow path length of the first flow path 61 is increased, the flow resistance of the first flow path 61 is increased, the effect of reducing the flow velocity in the first flow path 61 is increased, and the turbulent flow in the detection area DA is increased. Generation can be suppressed.

  Further, the air flow guiding wall 64 can be arranged such that the other end 642 not connected to the inner wall of the outer shell 63 is directed to the outside air outflow portion 632.

  Further, the auxiliary airflow guiding wall 65 may be installed in the vicinity of the housing inflow portion 101. By installing the auxiliary airflow guide wall 65, the airflow entering from the outside air inflow portion 631 is attracted to the outside air outflow portion 632, so that the inside of the second flow path 62 is rectified, and the fluid resistance in the second flow path 62 is reduced. Can be reduced.

(Modification 1)
Next, the configuration of the particle detection sensor 1A according to the first modification of the present invention will be described with reference to FIG. In the following description, a configuration that is a feature of the particle detection sensor 1A will be described, and different points from the particle detection sensor 1 in the above embodiment will be described. Other configurations are the same as those of the particle detection sensor 1.

  The particle detection sensor 1 </ b> A in the present modification includes the direction of the other end 642 that is not connected to the inner wall of the outer shell 63 among the airflow guiding walls 64 in the particle detection sensor 1 in Embodiment 1, and the outside air outflow portion 632. The positional relationship is different.

  Specifically, as shown in FIG. 8, in the particle detection sensor 1 </ b> A, the direction of the other end 642 not connected to the inner wall of the outer shell 63 in the airflow guiding wall 64 is the direction in which the outer air outflow portion 632 is located. It is arranged to go in the opposite direction. With this configuration, the distance between the housing outflow portion 102 and the outside air outflow portion 632 in the first flow path 61 is increased, and the number of places where the flow path is bent is increased. As a result, the first flow path 61 The flow path resistance becomes larger. By adopting such a configuration, the flow resistance of the first flow path 61 becomes larger than the flow resistance of the second flow path 62, and the airflow flowing in the first flow path 61 including the detection area DA is increased. By restricting the flow rate and slowing down the flow rate, it is possible to suppress the occurrence of turbulent flow in the detection area DA and to prevent a decrease in particle detection accuracy.

(Modification 2)
Next, the configuration of the particle detection sensor 1B according to Modification 2 of the present invention will be described with reference to FIG. In the following description, a configuration that is a feature of the particle detection sensor 1B will be described, and different points from the particle detection sensor 1 in the above embodiment will be described. Other configurations are the same as those of the particle detection sensor 1.

  In the particle detection sensor 1B in the present modification, the directional relationship between the airflow inflow direction of the housing inflow portion 101 and the airflow inflow direction of the outside air inflow portion 631 in the particle detection sensor 1 in the first embodiment is different. Further, the structure of the outside air outflow portion 632 is different from the position of the blower mechanism 66.

  Specifically, as shown in FIG. 9, in the particle detection sensor 1 </ b> B, the air blowing mechanism 66 is installed in the vicinity of the outside air inflow portion 631 and outside the outer shell 63, and the airflow that flows the outside air toward the inside of the outer shell 63. Is generated. The airflow generated by the blower mechanism 66 flows in the airflow inflow direction parallel to the X axis at the outside air inflow portion 631. A part of the outside air that flows in from the outside air inflow portion 631 flows into the inside of the housing 10 from the housing inflow portion 101 as an airflow in the airflow inflow direction parallel to the Z axis. That is, the airflow inflow direction of the housing inflow portion 101 and the airflow inflow direction of the outside air inflow portion 631 are orthogonal to each other.

  Further, the particle detection sensor 1B includes a first outside air outflow portion 671 and a second outside air outflow portion 672 as outside air outflow portions. Further, the first outside air outflow portion 671 and the second outside air outflow portion 672 are configured at different positions. The first flow path 61 is connected to the outside air inflow portion 631 and the first outside air outflow portion 671. Further, the second flow path 62 is connected to the outside air inflow portion 631 and the second outside air outflow portion 672.

  In the present modification, the cross-sectional area of the second outside air outflow portion 672 is larger than the cross-sectional area of the first outside air outflow portion 671. Further, the effective cross-sectional area of the second flow path 62 is larger than the effective cross-sectional area of the first flow path 61.

  By adopting such a configuration, the flow resistance of the first flow path 61 becomes larger than the flow resistance of the second flow path 62, and the airflow flowing in the first flow path 61 including the detection area DA is increased. By restricting the flow rate and slowing down the flow rate, it is possible to suppress the occurrence of turbulent flow in the detection area DA and to prevent a decrease in particle detection accuracy.

(Modification 3)
Next, the configuration of a particle detection sensor 1C according to Modification 3 of the present invention will be described with reference to FIG. In the following description, a configuration that is a feature of the particle detection sensor 1C will be described, and different points from the particle detection sensor 1 in the above embodiment will be described. Other configurations are the same as those of the particle detection sensor 1.

  The particle detection sensor 1 </ b> C in the present modification is different from the structure of the outside air inflow portion in the particle detection sensor 1 in the first embodiment in the position of the blower mechanism 66.

  Specifically, as shown in FIG. 10, in the particle detection sensor 1 </ b> C, the air blowing mechanism 66 is installed in the vicinity of the outside air outflow portion 632 and outside the outer shell 63, and the outside air is transferred from the inside of the outer shell 63 to the air blowing mechanism 66. It generates an air current that attracts you.

  Furthermore, the particle detection sensor 1C includes a first outside air inflow portion 681 and a second outside air inflow portion 682 as outside air inflow portions. Moreover, the 1st external air inflow part 681 and the 2nd external air inflow part 682 are comprised in another position. The first flow path 61 is connected to the first outside air inflow portion 681 and the outside air outflow portion 632. The second flow path 62 is connected to the second outside air inflow portion 682 and the outside air outflow portion 632.

By adopting such a configuration, the flow resistance of the first flow path 61 becomes larger than the flow resistance of the second flow path 62, and the airflow flowing in the first flow path 61 including the detection area DA is increased. By restricting the flow rate and slowing down the flow rate, it is possible to suppress the occurrence of turbulent flow in the detection area DA and to prevent a decrease in particle detection accuracy.
(Other)
As mentioned above, although the particle | grain detection sensor which concerns on this invention was demonstrated based on embodiment and a modification, this invention is not limited to the said embodiment and modification.

  For example, in the above-described embodiment, an example in which the housing 10 can be divided into the front cover 100 and the back cover 110 has been described, but the present invention is not limited thereto. The housing 10 may be integrally formed by injection molding using a resin material and a mold.

  Further, for example, in the above embodiment, the optical system 20 has the light projecting system 21 and the light receiving system 22 arranged in the horizontal direction across the detection area DA, but may be arranged in the vertical direction.

For example, in the above embodiment, the light projecting lens 122 and the light receiving lens 132 are shown as a member that condenses the light from the light projecting element 121 and a member that condenses the light to the light receiving element 131. A reflective member such as a mirror may be used.

In addition, a form obtained by making various modifications conceived by those skilled in the art with respect to each embodiment and modification, and any combination of components and functions in the embodiment without departing from the spirit of the present invention Forms to be made are also included in the invention.

DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C Particle detection sensor 10 Case 101 Case inflow part 102 Case outflow part 121 Light projecting element 131 Light receiving element 2 Particle 20 Optical system (sensor part)
DA detection area (sensor part)
61 1st flow path 62 2nd flow path 63 Outer shell 631 Outside air inflow part 632 Outside air outflow part 64 Air flow guide wall 641 One end part 642 Other end part 66 Blower mechanism 671 First outside air outflow part 672 Second outside air outflow part 681 First outside air inflow portion 682 Second outside air inflow portion

Claims (7)

A housing having a housing inflow portion through which outside air flows and a housing outflow portion through which the outside air flows out;
The scattered light of the light projecting element due to the particles contained in the outside air is received in a detection area provided inside the housing and in which the light projecting area of the light projecting element and the light receiving target area of the light receiving element overlap. a sensor unit for detecting the particles by,
Before comprises at least one external air inlet Kigaiki flows, and a shell having at least one external air outlet portion and the ambient air flows out,
The outer shell has a space between the housing outflow portion and the outside air outflow portion, and is installed around the housing.
A further air blowing mechanism is provided downstream of the outside air outflow portion ,
A part of the outside air is attracted from the outside air inflow part to the inside of the case through the case inflow part, passes through the detection region, and is discharged to the outside air outflow part through the case outflow part. A flow path;
A part of the outside air is attracted by the air blowing mechanism from the outside air inflow portion, passes between the outside of the housing and the inside of the outer shell, and is configured to be discharged to the outside air outflow portion. And
The fluid resistance of the first flow path is much larger than the fluid resistance of the second flow path,
In at least a part of the space between the housing outflow portion and the outside air outflow portion, the first flow path and the second flow path share a flow path,
An airflow guide wall that prevents the outside air passing through the second flow path from flowing from the housing outflow portion is provided in the vicinity of the housing outflow portion. Detection sensor. The particle detection sensor according to claim 1, wherein a length of the second flow path is shorter than a length of the first flow path. 3. The particle detection sensor according to claim 1, wherein an effective area of the second flow path is larger than an effective area of the first flow path.   The inner wall of the second flow path is constituted by the inner wall of the outer shell and the outer wall of the housing,
  The airflow guiding wall is in contact with the outer wall of the housing,
  The air flow guide wall has one end of both ends in a predetermined direction in contact with the inner wall of the outer shell.
Connected, the other end is not connected to the inner wall of the outer shell,
The particle detection sensor of any one of Claims 1-3 characterized by the above-mentioned.   The air flow guide wall is disposed such that the other end is directed in a direction opposite to the outside air outflow portion.
The particle | grain detection sensor of any one of Claims 1-4 characterized by the above-mentioned.   The airflow inflow direction of the housing inflow portion and the airflow inflow direction of the outside air inflow portion are orthogonal to each other.
The particle detection sensor of any one of Claims 1-5 characterized by the above-mentioned. The outside air outflow part is one,
The air blowing mechanism is provided downstream of the outside air outflow part,
As the outside air inflow portion, it has a first outside air inflow portion and a second outside air inflow portion,
The first flow path is connected to the first outside air inflow portion,
The second flow path is connected to the second outside air inflow portion,
The particle detection sensor according to claim 1, wherein the first outside air inflow portion and the second inflow portion are configured at different positions.