Dust sensor

Abstract

The utility model relates to a dust sensor. The dust sensor comprises a cover body, a box body, a light-emitting element and a light-receiving element, the cover body is provided with an air inlet; the box body is provided with an air outlet; the air inlet is communicated with the air outlet to form a ventilating duct; the light-emitting element and the light-receiving element are arranged in the box body; light paths of the light-emitting element and the light-receiving element pass through the ventilating duct; the dust sensor further comprises a circuit board assembly and a light guide element. The circuit board assembly comprises a circuit board and a supporting plate; light-emitting elements and light-receiving elements are mounted on the back surface of the circuit board; the supporting plate supports the circuit board in the box body; the two light guide elements respectively correspond to the light emitting element and the light receiving element and are arranged between the supporting plate and the bottom of the box body; the light guide element guides the light emitted by the light emitting element to the ventilating duct and guides the light reflected by the ventilating duct to the light receiving element. According to the utility model, the operation of inserting lead-type elements such as a light-emitting element and a light-receiving element into a circuit board for welding can be reduced, the quality is improved, and the cost is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of sensors, and in particular to a dust sensor. Background Technology

[0002] With increasing air pollution in modern environments, especially the rising concentration of particulate matter, more and more people are paying attention to indoor air quality. Therefore, air conditioning and ventilation systems connecting indoor and outdoor environments need to monitor airborne dust concentration in real time. Dust sensors are installed as accessories inside these systems. Typically, a dust sensor contains a ventilation duct, a light-emitting element, and a light-receiving element. Monochromatic parallel light emitted by the light-emitting element, when directed into the ventilation duct, is scattered by dust particles, attenuating its intensity. This attenuated light is then reflected by the light-receiving element, where a photoelectric reaction occurs, generating a recognizable electrical signal. This signal is used to measure the airborne dust concentration. However, existing dust sensors suffer from unstable detection quality and high production costs. Utility Model Content

[0003] The purpose of this invention is to solve the above-mentioned problems and provide a dust sensor.

[0004] The technical solution of this utility model is as follows: a dust sensor, including a cover, a housing, a light-emitting element, and a light-receiving element; the cover has an air inlet; the housing has an air outlet; the air inlet and the air outlet are connected to form a ventilation channel; the light-emitting element and the light-receiving element are disposed inside the housing; the light paths of the light-emitting element and the light-receiving element pass through the ventilation channel; the dust sensor also includes a circuit board assembly and a light guide element; the circuit board assembly includes a circuit board and a support plate; the light-emitting element and the light-receiving element are mounted on the back surface of the circuit board, which can reduce the need to insert lead-type components such as light-emitting elements and light-receiving elements into the circuit. The circuit board is welded to improve quality and reduce costs; a support plate holds the circuit board within the housing; two light guide elements are positioned between the support plate and the bottom of the housing, corresponding to the light-emitting element and the light-receiving element, respectively; the light guide element corresponding to the light-emitting element guides the light emitted by the light-emitting element to the ventilation duct; the light guide element corresponding to the light-receiving element guides the light reflected from the ventilation duct to the light-receiving element, thus establishing a light path starting from the light-emitting element, with the ventilation duct as the midpoint, and the light-receiving element as the endpoint, increasing the freedom of arrangement of the light-emitting and light-receiving elements, thereby improving quality and reducing costs.

[0005] Preferably, the light guide element includes an isosceles right-angled prism; one right-angled side of the isosceles right-angled prism faces the support plate, and the other right-angled side faces the ventilation channel; monochromatic parallel light emitted by the light-emitting element and monochromatic parallel light reflected from the ventilation channel can both enter the isosceles right-angled prism perpendicularly to the right-angled side; on the inclined surface of the isosceles right-angled prism, the light entering the isosceles right-angled prism can be reflected and exit from the right-angled side of the other isosceles right-angled prism; the exited light is directed toward the support plate or the ventilation channel; this simplifies the structural design of the light guide element and its installation structure, thereby improving quality and reducing cost; the isosceles right-angled prism is made of transparent material.

[0006] Furthermore, the placement angle of the isosceles right-angled prism is related to the refractive index of the isosceles diameter prism; thus, the angle between the normal of the hypotenuse of the isosceles right-angled prism and the light rays incident on the isosceles right-angled prism is greater than the critical angle of refraction, so that the light rays incident on the isosceles right-angled prism are completely emitted, which can reduce the loss of light rays and improve the detection accuracy of the dust sensor.

[0007] Furthermore, the light guide element also includes two convex lenses; the convex lenses are located at the center of the face containing one right-angle side of the isosceles right-angle prism, and are integrally formed with the isosceles right-angle prism to suppress light scattering, increase the amount of detection light, avoid the intrusion of interference light, and also generate light rays that are close to parallel, thereby improving detection efficiency; the convex lenses can be spherical lenses or aspherical lenses; the convex lenses are made of transparent material.

[0008] Furthermore, the light guide element also includes two rectangular fixing plates; the fixing plates are symmetrically arranged at both ends of the isosceles right-angle prism, which facilitates installation, simplifies the installation structure of the light guide element, and reduces production costs.

[0009] Furthermore, the air inlet and outlet are coaxially arranged; the circuit board has a hole A coaxial with the air inlet; the support plate has a hole B coaxial with the air inlet; holes A and B concentrate the dust entering the dust sensor into the ventilation duct for easy detection; the support plate has a cavity A matching the light-emitting element and a cavity B matching the light-receiving element to facilitate the formation of an optical path between the light-emitting element and the light-receiving element.

[0010] Furthermore, the back of the support plate is provided with a frame A surrounding cavity A and a frame B surrounding cavity B; the side of frame A facing the ventilation duct and the side of frame B facing the ventilation duct are respectively provided with light-transmitting hole A and light-transmitting hole B; both frame A and frame B abut against the bottom of the box; frame A and frame B respectively protect the light-emitting element and the light-receiving element to prevent dust from entering between the light-emitting element / light-receiving element and the light guide element, thus misleading the dust sensor's detection.

[0011] Furthermore, the front of the support plate is provided with a dust guide tube coaxial with hole B; the dust guide tube passes through hole A and extends towards the air inlet, reducing the probability of dust falling onto the circuit board.

[0012] Furthermore, the bottom of the box is provided with frame C and frame D; the side of frame C facing the ventilation duct and the side of frame D facing the ventilation duct are respectively provided with light-transmitting hole C and light-transmitting hole D; both frame C and frame D abut against the bottom of the support plate; frame A is inserted into frame C; frame B is inserted into frame D; frame C provides airtight protection for the light-emitting element; frame D provides airtight protection for the light-receiving element.

[0013] Furthermore, both frames A and B are symmetrically equipped with downward pressure strips that abut against the top of the fixing plate; both frames C and D are equipped with U-shaped upward pressure strips that abut against the bottom of the fixing plate; the downward pressure strips and the upward pressure strips work together to vertically limit the isosceles right-angle prism.

[0014] Furthermore, the outer edge of the fixing plate is provided with a through notch; both frame A and frame B are provided with a locking rib that matches the notch; the locking rib is inserted into the notch; the notch and the locking rib cooperate to avoid misinstallation, and at the same time limit the isosceles right angle prism accordingly.

[0015] Preferably, the back of the support plate is provided with a downwardly extending light-shielding plate A; the bottom of the box is provided with an upwardly extending light-shielding plate B; light-shielding plate A and light-shielding plate B are respectively provided with light-penetrating hole E and light-penetrating hole F; light-penetrating hole E and light-penetrating hole F are both smaller than the diameter of the optical path; this can reduce the amount of interference light generated by diffuse reflection inside the box and incident on the light guide element, thereby improving the detection accuracy.

[0016] Preferably, light-transmitting apertures A, B, and E are all arched doorway shapes; light-transmitting apertures C, D, and F are all inverted arched doorway shapes; the arc segments of the arched doorway shapes and the arc segments of the inverted arched doorway shapes are of equal size and correspond in height. This facilitates the installation of the light guide element and saves assembly costs.

[0017] Preferably, the light-emitting element emits infrared light, which can suppress unnecessary interference from visible light incidence, deterioration of the signal-to-noise ratio, and reduction in detection accuracy.

[0018] The beneficial effects of this utility model are as follows: The dust sensor of this utility model has the following advantages:

[0019] (1) This utility model can reduce the operation of inserting lead-type components such as light-emitting elements and light-receiving elements into the circuit board for soldering, thereby improving quality and reducing costs;

[0020] (2) The light-emitting element of this utility model is a simplified light guide element, and its related installation structure is also very simple, which can improve quality and reduce cost;

[0021] (3) The convex lens of this utility model can suppress light scattering, increase the amount of detection light, avoid interference light intrusion, and generate light that is close to parallel light, thereby improving detection efficiency. Attached Figure Description

[0022] Figure 1 This is a perspective view of the dust sensor of this utility model;

[0023] Figure 2 yes Figure 1 Side view;

[0024] Figure 3 yes Figure 2 AA section view;

[0025] Figure 4 yes Figure 3 BB section view;

[0026] Figure 5 yes Figure 4 CC-rotated sectional view;

[0027] Figure 6 It is a 3D view of the circuit board assembly;

[0028] Figure 7 It is a 3D view of a circuit board assembly with a light guide element installed;

[0029] Figure 8 yes Figure 7 A bottom view;

[0030] Figure 9 yes Figure 8 DD sectional view;

[0031] Figure 10 It is a 3D view of the circuit board;

[0032] Figure 11 It is a 3D view of the support plate;

[0033] Figure 12 It is a three-dimensional light guide element Figure 1 ;

[0034] Figure 13 It is a three-dimensional light guide element Figure 2 ;

[0035] Figure 14 It is a 3D view of the box;

[0036] Figure 15 yes Figure 14 Top view;

[0037] In the diagram: 1. Cover, 11. Air inlet, 2. Box body, 21. Air outlet, 22. Frame C, 221. Light-transmitting hole C, 23. Frame D, 231. Light-transmitting hole D, 24. Top strip, 25. Light-shielding plate B, 251. Light-transmitting hole F, 3. Light-emitting element, 4. Light-receiving element, 5. Ventilation duct, 61. Circuit board, 611. Pin hole, 612. Hole A, 62. Support plate, 621. 622. Through-cavity A, 623. Through-cavity B, 624. Frame A, 6241. Light-transmitting hole A, 625. Frame B, 6251. Light-transmitting hole B, 626. Dust guide tube, 627. Lower pressure strip, 628. Clamping strip, 629. Light-shielding plate A, 6291. Light-transmitting hole E, 7. Light guide element, 71. Isosceles right-angle prism, 72. Convex lens, 73. Fixing plate, 731. Notch. Detailed Implementation

[0038] Example 1: See Figure 1-15 A dust sensor includes a cover 1, a housing 2, a light-emitting element 3, and a light-receiving element 4. The cover 1 has an air inlet 11; the housing 2 has an air outlet 21; the air inlet 11 and the air outlet 21 are connected to form a ventilation duct 5; the light-emitting element 3 and the light-receiving element 4 are disposed inside the housing 2; the light paths of the light-emitting element 3 and the light-receiving element 4 pass through the ventilation duct 5; the dust sensor also includes a circuit board 61 assembly and a light guide element 7; the circuit board 61 assembly includes a circuit board 61 and a support plate 62; the light-emitting element 3 and the light-receiving element 4 are mounted on the back surface of the circuit board 61, which can reduce the need to insert lead-type components such as the light-emitting element 3 and the light-receiving element 4 into the circuit board. The welding operation is performed on 61 to improve quality and reduce costs; the support plate 62 supports the circuit board 61 inside the box 2; there are two light guide elements 7, which are respectively set between the support plate 62 and the bottom of the box 2, corresponding to the light-emitting element 3 and the light-receiving element 4; the light guide element 7 corresponding to the light-emitting element 3 guides the light emitted by the light-emitting element 3 to the ventilation channel 5; the light guide element 7 corresponding to the light-receiving element 4 guides the light reflected from the ventilation channel 5 to the light-receiving element 4, so as to establish a light path with the light-emitting element 3 as the starting point, the ventilation channel 5 as the midpoint, and the light-receiving element 4 as the ending point, increasing the degree of freedom in the arrangement of the light-emitting element 3 and the light-receiving element 4, thereby improving quality and reducing costs.

[0039] Compared with the prior art, the present invention can reduce the operation of inserting lead-type components such as light-emitting element 3 and light-receiving element 4 into circuit board 61 for soldering, thereby improving quality and reducing costs.

[0040] The circuit board 61 has two or more pin holes 611; the support plate 62 has a pin 621 on the front side that mates with the pin holes 611; the pin 621 mates with the pin holes 611, which facilitates the assembly of the circuit board 61 and the support plate 62.

[0041] The light guide element 7 includes an isosceles right-angled prism 71; one right-angled side of the isosceles right-angled prism 71 faces the support plate 62, and the other right-angled side faces the ventilation channel 5; the monochromatic parallel light emitted by the light-emitting element 3 and the monochromatic parallel light reflected from the ventilation channel 5 can both enter the isosceles right-angled prism 71 perpendicularly to one right-angled side; on the inclined surface of the isosceles right-angled prism 71, the light entering the isosceles right-angled prism 71 can be reflected and exit from the right-angled side of the other isosceles right-angled prism 71; the exited light is directed toward the support plate 62 or the ventilation channel 5; this simplifies the structural design of the light guide element 7 and its installation structure, thereby improving quality and reducing cost; the isosceles right-angled prism 71 is made of transparent material.

[0042] The placement angle of the isosceles right-angle prism 71 is related to the refractive index of the isosceles diameter prism; thus, the angle between the normal of the hypotenuse of the isosceles right-angle prism 71 and the light rays incident on the isosceles right-angle prism 71 is greater than the critical angle of refraction, and the light rays incident on the isosceles right-angle prism 71 are completely emitted, which can reduce the loss of light and improve the detection accuracy of the dust sensor.

[0043] The light guide element 7 also includes two convex lens plates 72; the convex lens plate 72 is disposed at the center of the plane containing one right-angle side of the isosceles right-angle prism 71, and is integrally formed with the isosceles right-angle prism 71, suppressing light scattering, increasing the amount of detection light, avoiding the intrusion of interference light, and also generating light rays that are close to parallel light, thereby improving detection efficiency; the convex lens plate 72 can be a spherical lens or an aspherical lens; the convex lens plate 72 is made of transparent material; in this embodiment, the convex lens plate 72 is an aspherical lens.

[0044] The light guide element 7 also includes two rectangular fixing plates 73; the fixing plates 73 are symmetrically arranged at both ends of the isosceles right-angle prism 71, which facilitates installation, simplifies the installation structure of the light guide element 7, and reduces production costs.

[0045] The air inlet 11 and the air outlet 21 are coaxially arranged; the circuit board 61 has a hole A 612 coaxial with the air inlet 11; the support plate 62 has a hole B coaxial with the air inlet 11; the holes A 612 and B concentrate the dust entering the dust sensor into the ventilation duct 5 for easy detection; the support plate 62 has a cavity A 622 matching the light-emitting element 3 and a cavity B 623 matching the light-receiving element 4 to facilitate the formation of an optical path between the light-emitting element 3 and the light-receiving element 4.

[0046] The back of the support plate 62 is provided with a frame A 624 surrounding the cavity A 622 and a frame B 625 surrounding the cavity B 623; the side of frame A 624 facing the ventilation duct 5 and the side of frame B 625 facing the ventilation duct 5 are respectively provided with light-transmitting holes A 6241 and B 6251; both frames A 624 and B 625 abut against the bottom of the box 2; frames A 624 and B 625 respectively protect the light-emitting element 3 and the light-receiving element 4 to prevent dust from entering between the light-emitting element 3 / light-receiving element 4 and the light guide element 7, thus misleading the dust sensor detection.

[0047] The two light guide elements 7 have the same shape and size, and can be interchanged to a certain extent, which facilitates assembly and subsequent maintenance, and reduces the number of manufacturing molds required for the light guide elements 7, thereby reducing production costs.

[0048] The support plate 62 has a dust guide tube 626 coaxial with the hole B on the front side; the dust guide tube 626 passes through the hole A 612 and extends towards the air inlet 11, reducing the probability of dust falling onto the circuit board 61.

[0049] The bottom of the box 2 is provided with frame C 22 and frame D 23; the side of frame C 22 facing the ventilation duct 5 and the side of frame D 23 facing the ventilation duct 5 are respectively provided with light-transmitting holes C 221 and D 231; both frames C 22 and D 23 abut against the bottom of the support plate 62; frame A 624 is inserted into frame C 22; frame B 625 is inserted into frame D 23; frame C 22 provides airtight protection for the light-emitting element 3; frame D 23 provides airtight protection for the light-receiving element 4.

[0050] Frame A 624 and Frame B 625 are symmetrically provided with lower pressure strips 627 that abut against the top of the fixing plate 73; Frame C 22 and Frame D 23 are both provided with U-shaped upper top strips 24 that abut against the bottom of the fixing plate 73; The lower pressure strips 627 and the upper top strips 24 cooperate to vertically limit the isosceles right angle prism 71.

[0051] The outer edge of the fixing plate 73 is provided with a through notch 731; both frame A 624 and frame B 625 are provided with a retaining 628 that matches the notch 731; the retaining 628 is inserted into the notch 731; the notch 731 and the retaining 628 cooperate to avoid misinstallation, and at the same time limit the isosceles right angle prism 71 accordingly.

[0052] The light-emitting element 3 emits infrared light, which can suppress unnecessary interference from visible light incidence, deterioration of the S / N ratio, and reduction of detection accuracy.

[0053] The working principle of this embodiment is as follows: the light-emitting element 3 and the light-receiving element 4 are surface-mounted, which can reduce the operation of inserting lead-type elements such as the light-emitting element 3 and the light-receiving element 4 into the circuit board 61 for soldering; the light guide element 7 increases the degree of freedom in the arrangement of the light-emitting element 3 and the light-receiving element 4; the isosceles right-angle prism 71 can simplify the structural design of the light guide element 7 and its mounting structure design; the convex lens 72 can suppress light scattering, increase the amount of detection light, avoid the intrusion of interference light, and also generate light rays that are close to parallel light, thereby improving detection efficiency.

[0054] Example 2: Example 2 is basically the same as Example 1, and the similarities will not be repeated. The difference is that: the back of the support plate 62 is provided with a downwardly extending light-shielding plate A 629; the bottom of the box 2 is provided with an upwardly extending light-shielding plate B 25; the light-shielding plate A 629 and the light-shielding plate B 25 are respectively provided with light-penetrating holes E 6291 and F 251; the light-penetrating holes E 6291 and F 251 are both smaller than the diameter of the optical path; this can reduce the amount of interference light generated by diffuse reflection in the box 2 and incident on the light guide element 7, thereby improving the detection accuracy.

[0055] A light-shielding plate B 25 is installed between adjacent light-shielding plates A 629.

[0056] Light-transmitting apertures A (6241), B (6251), and E (6291) are all arched doorway shapes; light-transmitting apertures C (221), D (231), and F (251) are all inverted arched doorway shapes. The arc segments of the arched doorway shapes and the arc segments of the inverted arched doorway shapes are of equal size and correspond in height. This facilitates the installation of the light guide element 7 and saves assembly costs.

Claims

1. A dust sensor, comprising a cover, a housing, a light-emitting element, and a light-receiving element; the cover has an air inlet; the housing has an air outlet; the air inlet and the air outlet are connected to form a ventilation channel; the light-emitting element and the light-receiving element are disposed inside the housing; the optical paths of the light-emitting element and the light-receiving element pass through the ventilation channel; characterized in that, The dust sensor also includes a circuit board assembly and a light guide element; the circuit board assembly includes a circuit board and a support plate; a light-emitting element and a light-receiving element are mounted on the back surface of the circuit board; the support plate supports the circuit board inside the housing. There are two light guide elements, one corresponding to the light-emitting element and the other to the light-receiving element, which are located between the support plate and the bottom of the box. The light guide element corresponding to the light-emitting element guides the light emitted by the light-emitting element to the ventilation channel; the light guide element corresponding to the light-receiving element guides the light reflected from the ventilation channel to the light-receiving element.

2. The dust sensor according to claim 1, characterized in that: The light guide element includes an isosceles right-angled prism; one right-angled side of the isosceles right-angled prism faces the support plate, and the other right-angled side faces the ventilation channel; the isosceles right-angled prism is made of transparent material.

3. The dust sensor according to claim 2, characterized in that: The light guide element also includes two convex lenses; the convex lenses are located at the center of the face containing one right-angle side of the isosceles right-angle prism and are integrally formed with the isosceles right-angle prism; the convex lenses are made of transparent material.

4. The dust sensor according to claim 2, characterized in that: The light guide element also includes two rectangular fixing plates; the fixing plates are symmetrically arranged at both ends of the isosceles right-angle prism.

5. The dust sensor according to claim 1 or 4, characterized in that: The air inlet and air outlet are coaxially arranged; the circuit board has a hole A coaxial with the air inlet; the support plate has a hole B coaxial with the air inlet; the support plate has a cavity A that matches the light-emitting element and a cavity B that matches the light-receiving element.

6. The dust sensor according to claim 5, characterized in that: The back of the support plate is provided with frame A surrounding cavity A and frame B surrounding cavity B; the side of frame A facing the ventilation duct and the side of frame B facing the ventilation duct are respectively provided with light-transmitting hole A and light-transmitting hole B; both frame A and frame B abut against the bottom of the box.

7. The dust sensor according to claim 5, characterized in that: The front of the support plate is equipped with a dust guide tube coaxial with hole B; the dust guide tube passes through hole A and extends towards the air inlet.

8. The dust sensor according to claim 6, characterized in that: The bottom of the box is provided with frame C and frame D; the side of frame C facing the ventilation duct and the side of frame D facing the ventilation duct are respectively provided with light-transmitting hole C and light-transmitting hole D; both frame C and frame D abut against the bottom of the support plate; frame A is inserted into frame C; frame B is inserted into frame D.

9. The dust sensor according to claim 4, characterized in that: The outer edge of the fixed plate has a through notch; both frame A and frame B have a retaining rib that matches the notch; the retaining rib is inserted into the notch.

10. The dust sensor according to claim 1, characterized in that: The back of the support plate is provided with a downward-extending light-shielding plate A; the bottom of the box is provided with an upward-extending light-shielding plate B; light-shielding plate A and light-shielding plate B are respectively provided with light-penetrating hole E and light-penetrating hole F; both light-penetrating hole E and light-penetrating hole F are smaller than the diameter of the light path.

Images