CN217443110U

CN217443110U - Ultra-thin labyrinth structure

Info

Publication number: CN217443110U
Application number: CN202221173272.8U
Authority: CN
Inventors: 林照临; 王�锋; 梁继专; 钟松琊; 陈小牧
Original assignee: Fujian Haomagic Electronic Technology Co ltd
Current assignee: Fujian Shouzhong'an Intelligent Technology Co.,Ltd.
Priority date: 2022-05-17
Filing date: 2022-05-17
Publication date: 2022-09-16
Anticipated expiration: 2032-05-17

Abstract

The invention provides an ultra-thin labyrinth structure, which can reduce a smoke-free background signal of a receiving pipe while realizing ultra-thin type, ensures smoke detection capability, can eliminate condensation and dust, has high overall strength, vibration resistance and wide applicable temperature range, can be suitable for narrow environments such as the inside of a battery pack, and comprises a labyrinth main body, wherein the labyrinth main body comprises a labyrinth base, an optical barrier and a labyrinth top cover, one end of the optical barrier is connected with the labyrinth base, and the other end of the optical barrier is connected with the labyrinth top cover; the bottom of the labyrinth main body is fixedly provided with a circuit board; the inner surface of the labyrinth top cover, the inner surface of the optical barrier and the labyrinth side of the circuit board form a smoke detection cavity; the method is characterized in that: the circuit board is provided with a patch type transmitting tube and a patch type receiving tube, and optical main shafts of the transmitting tube and the receiving tube are vertical to the circuit board; the inner surface of the labyrinth top cover is a sectional type reflecting surface with high middle and low periphery.

Description

Ultra-thin labyrinth structure

Technical Field

The invention relates to the technical field of smoke detectors, in particular to an ultra-thin labyrinth structure.

Background

The popularization of the application of power lithium batteries and the frequent thermal runaway fire of the lithium batteries generate the monitoring requirement on the thermal runaway condition of the batteries. One of the main ways to monitor thermal runaway is to detect the electrolyte volatilization, released gas and smoke particles generated during the initial stage of thermal runaway, and the photoelectric smoke sensor can detect the electrolyte volatilization particles and smoke particles generated by combustion in the initial stage.

The lithium battery pack is particularly used for a battery pack of a new energy automobile, the volume space of the lithium battery pack is limited, the smaller the volume of a circuit board or an auxiliary functional part of a non-battery energy storage battery core part is, the better the volume is, and the larger the size of a traditional smoke detector is, so that a new smoke detector labyrinth with an ultrathin structure needs to be designed, and the smoke detector labyrinth can be flexibly installed inside the battery pack. Fill electric pile, energy storage equipment and other power equipment boxes and also have the demand to potential fire risk control, and this type of equipment inner space is also narrow and small, has above same demand. On the basis, the requirements brought by the use environment, such as a wider temperature range, a condensation problem and a strong vibration condition, need to be considered. Therefore, only when the requirements are solved, the new maze structure design can meet the use requirements of the scenes.

Designing an ultra-thin labyrinth structure needs to solve two problems: firstly, selecting a small-volume optical device; and the problem of optical reflection in a small-size low-height maze is solved. In order to solve the first problem, a surface-mounted optical device with low height is generally adopted in the field, so that the occupied space is reduced, and the height size of the maze is reduced. However, the optical principal axis of the surface-mounted optical device is generally perpendicular to the mounting surface, and the light emitted from the light-emitting tube is reflected toward the inner surface of the labyrinth detection chamber, and the reflected light is stronger and exponentially increased as the height of the labyrinth is lower, thereby causing the second problem mentioned above, such that the smoke-free background signal of the receiving tube is too large. Excessive smokeless background signal can lead to two problems: firstly, a sufficient dynamic range cannot be provided for smoke detection, and an overlarge smoke-free background signal easily causes smoke signal saturation and even cannot work normally, especially in the case of high-reflection white smoke; secondly, the resolution ratio of the rarefied smoke is reduced, because the overlarge smoke-free background signal cannot be configured with high gain, and the larger the current of the receiving tube is, the more the particulate noise of the receiving tube is, the larger the current is, the weaker signal to be detected is submerged, and the problem of rarefied smoke detection can be caused. The design goal is therefore: while realizing ultra-thin type, the smokeless background signal of the receiving tube is limited within a certain range, for example, not more than 10% of the range of the received signal, the lower the signal, the better.

There are generally two methods of reducing or eliminating the smokeless background signal in the prior art: firstly, a wave absorbing method is adopted, and a wave absorbing material absorbs most incident light; secondly, the reflected light is guided to other directions to avoid being reflected back to the receiving tube. The wave absorbing method is to design a wave absorbing coating or control the granularity of a reflecting surface so as to reduce incident light, and after the method is used for a long time in an actual scene, dust is inevitably accumulated on the inner surface of a labyrinth. In addition, other factors such as condensation also can seriously affect the wave absorbing effect, and the coating process and the service life of the coating also can affect the labyrinth performance. The second method adopts the principle of reflection, reflects the incident light to other directions, and avoids irradiating a receiving tube to cause exposure. Typical methods are to design the main reflecting surface as a cone top, but the cone top needs a sufficient height, and thus is suitable for a large-sized labyrinth and not suitable for a low-height ultra-thin labyrinth. Moreover, the influence of the accumulated dust can also influence the maze at the top of the cone, because the top of the cone is easy to hang dust, the cone top is nearest to the optical device, and any slight change can cause the optical change. In addition, the labyrinthine design of the cusps is detrimental to the consistency of the mechanical design and the control production.

Therefore, in view of the above problems, it is currently required to design a new labyrinth structure suitable for a narrow environment such as the inside of a battery pack.

Disclosure of Invention

In order to solve the above-mentioned problems, the present invention provides an ultra-thin labyrinth structure, which can reduce the smokeless background signal of the receiving tube while realizing ultra-thin shape, ensure the smoke detection capability, and can eliminate condensation and dust, has high overall strength, vibration resistance, and a wide temperature range of application, and can be applied to a narrow environment inside a battery pack, for example.

The technical scheme is as follows:

an ultra-thin labyrinth structure comprises a labyrinth main body, wherein the labyrinth main body comprises a labyrinth base, an optical barrier and a labyrinth top cover, one end of the optical barrier is connected with the labyrinth base, and the other end of the optical barrier is connected with the labyrinth top cover; the bottom of the labyrinth main body is fixedly provided with a circuit board; the inner surface of the labyrinth top cover, the inner surface of the optical barrier and the labyrinth side of the circuit board form a smoke detection cavity;

the method is characterized in that: the circuit board is provided with a patch type transmitting tube and a patch type receiving tube, and optical main shafts of the transmitting tube and the receiving tube are vertical to the circuit board; the inner surface of the labyrinth top cover is a sectional type reflecting surface with high middle and low periphery.

Further, the segmented reflective surface in combination with the inner surface of the optical barrier form at least four stages of reflective surfaces: the first stage reflecting surface is a spherical surface at the center of the labyrinth top cover, the second stage reflecting surface is a variable slope surface, the third stage reflecting surface is a slope surface, the variable slope surface is respectively and smoothly connected with the spherical surface and the slope surface, and the fourth stage reflecting surface is the inner surface of the optical barrier.

Further, the spherical radius is 0.1-0.6 mm; the section curve of the variable slope curved surface is a quadratic curve or a cubic curve, and the slope of the section curve is larger when the section curve is closer to the center of the labyrinth top cover; the slope of the slope surface is 3-10 degrees, and the length of the slope is 1-6 mm.

Furthermore, the optical barrier is formed by annularly arranging basic units with broken lines on the cross section in a rotary shutter mode, the broken lines are broken lines formed by intersecting two line segments or two arc line segments at one point to form an acute angle, the angle of the acute angle is recorded as beta, and the angle of the acute angle is more than or equal to 45 degrees and less than 90 degrees; the height h of the broken lines is recorded as the distance between the intersection point of the broken lines and the perpendicular line of a line segment formed by two end points of the broken lines, the distance w between the adjacent broken lines is recorded as the distance between the outer end points of the two adjacent broken lines in the direction perpendicular to the circular radius of the ring, and the height h of the broken lines is set to be larger than the distance w between the adjacent broken lines; the end point of the folding line in the labyrinth is an oblique cutting plane, the oblique cutting plane is on the annular circular radius line, the included angle between the oblique cutting plane and the extension line of the folding line is marked as alpha, and the alpha is more than or equal to 25 degrees and less than or equal to 55 degrees; the end point of the fold line outside the labyrinth is also a chamfer, and the chamfer faces the outer side of the labyrinth main body.

Further, the inner surfaces of the sectional type reflecting surface and the optical barrier are black matte surfaces.

Furthermore, the labyrinth main body is in a central symmetry shape, the section parallel to the labyrinth base is circular or elliptical, and the section vertical to the labyrinth base is in a trapezoid-like shape; the maze main part adopts black material of moulding plastics, the integral type design.

Further, the emission tube includes one or more emission tubes, the plurality of emission tubes are symmetrically arranged, the geometric center of the emission tubes is aligned with the central point of the maze body, and if only one emission tube is arranged, the luminous center of the emission tube is aligned with the central point of the maze body; the receiving tubes comprise one or more receiving tubes, and the receiving tubes are arranged on an arc taking the center point of the transmitting tube as the center of a circle; the distance from the central point of the transmitting tube to the edge of the photosensitive area of the receiving tube is 1.5 mm-5 mm.

Furthermore, a groove-shaped structure communicated with the inside of the labyrinth main body is arranged at the joint of the optical barrier and the labyrinth top cover, and the width of the groove-shaped structure is narrow inside and wide outside; the segmented reflective surface is provided as a hydrophobic surface.

Furthermore, an ear-shaped area with a fixing hole extends out of the periphery of the labyrinth base, and the ear-shaped area is used for fixing the labyrinth main body with the circuit board and other mechanism parts; the fixing holes are fixed by using elastic bolts or reeds; the labyrinth base is a thickened machine component.

Furthermore, the labyrinth main body is made of a material with a wide temperature range and a low coefficient of thermal expansion and cold contraction deformation; the outer surface of the labyrinth cap is a non-planar concave shape that varies with the segmented reflective surface of the inner surface of the labyrinth cap.

The invention has the beneficial effects that:

1. the invention adopts the patch type transmitting tube and receiving tube and the inner surface of the labyrinth top cover to be the sectional type reflecting surface, so as to reduce the height of the smoke detection cavity, the integral height of the labyrinth is compressed to be within 11mm, the typical value is 8mm, the ultra-thin structural design is realized, meanwhile, the reflected light is reflected once or for many times by the sectional reflecting surface of the labyrinth top cover and is guided to the inner surface of the optical barrier, multiple reflections from the inside to the outside are formed on the optical barrier, and finally the reflected light is eliminated or is directly guided to the outside of the maze, therefore, the smokeless background signal of the receiving tube caused by reflected light is effectively reduced, the maze with the reduced height can still effectively limit the smokeless background signal of the receiving tube, and the smokeless background signal is controlled within the range without influencing the signal-to-noise ratio and the sensitivity of the smoke signal, so that the technical effect of improving the smoke detection capability is achieved.

2. The invention also avoids the conical sharp top through the spherical design of the center of the labyrinth top cover, is beneficial to controlling the consistency of machining and avoiding the problem that the sharp top is hung with ash or condensed dew, influences optical signals and further improves the smoke detection capability.

3. The inner surface of the labyrinth top cover is of a structure with a high middle part and a low periphery, a groove-shaped structure communicated with the inside of the labyrinth main body is arranged at the joint of the optical barrier and the labyrinth top cover, the width of the groove-shaped structure is narrow inside and wide outside, and a sectional type reflecting surface is arranged to be a hydrophobic surface; thereby achieving the technical effect of conveniently removing condensation and dust.

4. According to the invention, by designing the labyrinth base with the circular or oval cross section, a plurality of lug-shaped areas with fixing holes can be symmetrically extended on the periphery of the base and are fixed by the elastic bolts or reeds, so that the mounting or vibration dislocation is prevented, the problem of mechanism stress generated by completely using screws for fixing is avoided, and the mechanism stress is easy to cause mechanism looseness and even damage under a strong vibration environment; the labyrinth main body is designed to be an integrated plastic structure, so that mechanisms buckled with each other are reduced; thereby achieving the technical effects of high overall strength and vibration resistance.

5. The labyrinth main body is made of a material with a wide temperature range and a low coefficient of thermal expansion and cold contraction deformation; the outer surface of the labyrinth top cover is in a non-planar concave shape and changes along with a sectional type reflecting surface of the inner surface of the labyrinth top cover so as to reduce injection molding shrinkage caused by uneven thickness of materials; thereby achieving the technical effect of wide applicable temperature range.

Drawings

FIG. 1 is a schematic view of the overall structure of the maze of the present invention;

FIG. 2 is a schematic of the segmented reflection of the present invention;

FIG. 3 is a schematic representation of the reflection of the optical barrier of the present invention;

FIG. 4 is a schematic view of an optical barrier of the present invention-broken line type;

FIG. 5 is a schematic view of an optical barrier of the present invention-of the inside-outside double layer type;

FIG. 6 is a schematic view of the groove structure of the present invention;

fig. 7 is a schematic view of the placement of the optical device of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples.

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. The conditions in the embodiments can be further adjusted according to specific conditions, and simple modifications of the method of the present invention based on the concept of the present invention are within the scope of the claimed invention.

The labyrinth design is an important part of the design of the photoelectric smoke detector. For a smoke detector, a labyrinth is a smoke detection cavity formed by a surrounding structure, the surrounding structure is provided with an airflow channel for the smoke to be detected to enter and exit, and the labyrinth is simply a ventilation and light-tight structural member and provides a stable smoke detection cavity and environment for internal optical devices. Externally, the basic function of the maze is to inhibit external ambient light from entering the interior of the labyrinth while ensuring that airflow containing microparticles smoothly enters the interior detection cavity of the labyrinth, so as to create a stable optical detection environment for the interior detection cavity; for the most part, the internal detection cavity formed by the labyrinth and the corresponding optics form a complete optical detection path. The channel comprises three links, firstly, a light-emitting tube emits detection light to a detection cavity; then, the detection light irradiates on the smoke or microparticles in the cavity to generate scattering or reflection; and the scattered or reflected light part is received by the photoelectric receiving tube to generate a receiving signal. The optical device is easily influenced by external environment light, the labyrinth ensures the functions, and a stable internal environment is provided for photoelectric detection.

The traditional smoke detector for fire fighting is mainly used in indoor and public places, has relatively stable temperature and humidity and is fixedly installed. However, the working scenes of the power battery pack, the charging pile and the power equipment box are much more complex, so that the power battery pack, the charging pile and the power equipment box not only can meet the conventional temperature change, but also can be considered and adapted to the large temperature difference requirement of the outdoor environment, and can be possibly used for sealing the heating working environment. An important factor in measuring a power lithium battery pack is that its energy density is higher and better, especially in new energy automobile applications, so its internal space is in the order of magnitude of earth, considering different cell sizes and compatibility issues, it would be the best design if the sensor could be sized in one dimension close to or lower than a small cylindrical cell, such as the 18650 and 21700 cells of tesla with diameters of 18mm and 21mm, respectively. If the vehicle-mounted type vibration isolation device is used on a vehicle, the vehicle-mounted type vibration isolation device can bear strong vibration environment during driving. Therefore, the smoke detector labyrinth which can be used for the power lithium battery pack is designed, the performance requirement of the smoke detector labyrinth is greater than the performance standard of the existing photoelectric smoke detector for fire fighting, and the following points are summarized: 1. the working temperature range of the vehicle-mounted device is at least-40 ℃ to +85 ℃, and is typically-40 ℃ to +125 ℃, which is wider than the conventional working temperature range of-10 ℃ to +55 ℃ for fire fighting; 2. if the labyrinth is used for a vehicle, the labyrinth of the smoke detector for the battery pack must adapt to a high-strength driving vibration environment, which is completely different from the static fixed installation for fire fighting; 3. the labyrinth design must also consider how to adapt to the problem of water vapor and even condensation so as to avoid the problem of misinformation of condensation in the existing smoke sense. In summary, in the above-described specific use environment, there are demands for a small mounting size, and also demands for use in a wide temperature range and in a strong vibration environment, and in addition, there is a possibility that dew may be generated in the working environment.

In order to meet the requirements, the invention provides the following labyrinth structure design.

As shown in fig. 1, an ultra-thin labyrinth structure includes a labyrinth main body, where the labyrinth main body includes a labyrinth base 13, an optical barrier 12, and a labyrinth top cover 11, and one end of the optical barrier 12 is connected to the labyrinth base 13, and the other end is connected to the labyrinth top cover 11; the bottom of the maze main body is fixedly provided with a circuit board 2; the inner surface of the labyrinth cover 11, the inner surface of the optical barrier 12 and the labyrinth side of the circuit board 2 form a smoke detection chamber 15.

A patch type transmitting tube 3(LED) and a receiving tube (PD) are mounted on the circuit board 2, wherein the receiving tube 41 and the receiving tube 42 are shown in the figure, and optical main shafts of the transmitting tube 3 and the receiving tube are vertical to the circuit board 2; considering the thickness of the circuit board, the thickness of the shell and the installation margin of the mechanism, the whole height of the labyrinth is compressed to be within 11mm, and the typical value is 8mm, so that the sensor with the ultrathin labyrinth can be flexibly used in various occasions with narrow space.

As shown in fig. 2 to 3, the inner surface of the labyrinth cover 11 is a sectional reflecting surface 14 having a high middle portion and a low periphery. The segmented reflective surface 14 in combination with the inner surface of the optical barrier 12 constitute at least four stages of reflective surfaces: the first stage reflecting surface is a spherical surface at the center of the labyrinth top cover 11, the second stage reflecting surface is a variable slope curved surface, the third stage reflecting surface is a slope surface, the variable slope curved surface is respectively and smoothly connected with the spherical surface and the slope surface, and the fourth stage reflecting surface is the inner surface of the optical barrier 12. Therefore, the light emitted from the LED is irradiated onto the segmented reflective surface 14, and after one or more reflections, the light reaches the optical barrier 12, and is reduced or guided to the outside of the maze after passing through the optical barrier 12, and since the maze material is a black light-absorbing material, the light intensity is generally almost reduced after three reflections. The 4 types of light reflection are illustrated in fig. 2: a. b, c and d, and the following are detailed descriptions: 1. ray a is a ray close to the main optical axis of the light-emitting tube 3 and can be reflected by the first-stage spherical surface to the optical barrier 12; 2. the light ray b is the light ray reflected to the optical barrier 12 by the variable slope surface of the second stage; 3. the light ray c is reflected to the optical barrier 12 by the slope surface of the third stage; 4. ray d is similar to ray b, but is not directly reflected to the optical barrier 12, but is reflected to the optical barrier 12 via the third stage.

The spherical radius is 0.1-0.6 mm, and preferably 0.25 mm; the section curve of the variable slope curve is a quadratic curve or a cubic curve, preferably a right-opening parabola such as a first quadrant part with y ^ 2x and 0 ≦ x ≦ 4mm, preferably a part with 0 ≦ x ≦ 2 mm. The slope of the profile curve is larger as the profile curve is closer to the center of the labyrinth top cover, so that the variable slope curve can provide rapid height reduction and large-angle reflection incident light; assuming that the slope length is SL and the slope height is SH, the slope of the slope is 3-10 DEG, which can be expressed as tan of 3 DEG or less according to a trigonometric function ^-1 (SH/SL) is less than or equal to 10 degrees, and the length of the slope is 1-6 mm, preferably 2 mm. In order to realize the ultra-thin maze design, the above small size is preferred for the variable slope surface and the slope surface length to control the diameter size of the maze, which brings two benefits: firstly, the small diameter is coordinated with the height of the thin labyrinth, and the shock resistance is better; and secondly, the light rays reflected by the sectional type reflecting surface are favorably dropped on the optical barrier on the side surface of the maze as much as possible instead of being reflected to the circuit board. The inner surfaces of the sectional type reflecting surface and the optical barrier are black matte surfaces, and black surfaces are required to be used for the circuit board.

The spherical protrusions in the first stage are beneficial to controlling the consistency of machining and avoiding the influence of ash hanging on the top of the tip on optical signals. The variable slope curved surface in the second stage can provide rapid slope change to reduce the distance from the light-emitting tube to the center of the sectional type reflecting surface, and is also favorable for controlling the net height H of the smoke detection cavity. The third stage is a slope with a fixed slope, provides a form with a high middle part and two low ends, and is beneficial to discharging accumulated dust and condensation from a maze. And the fourth stage is a side optical barrier which is used as a last extinction mechanism to reduce or guide incident light to the outside of the labyrinth. Because the curvature change of the spherical surface in the first stage and the curvature change of the variable slope curved surface in the second stage are both larger, light near the main optical axis can be emitted to the side optical barrier to avoid being irradiated on the PD, so that the distance between the central point of the LED and the edge part of the PD light sensing part is reduced as much as possible, the optical intersection part can be effectively increased, the internal reflection is reduced, and the integrated device is more favorable.

As shown in fig. 4, the optical barrier is formed by arranging basic units with broken lines in a circular mode in a rotary louver mode, wherein the broken lines are broken lines with two line segments intersecting at a point to form an acute angle, and the angle of the acute angle is represented as beta, and beta is more than or equal to 45 degrees and less than 90 degrees. The height h of the fold lines is recorded as the distance between the perpendicular line of the line segment formed by the intersection point of the fold lines and two end points of the fold lines, the distance w between adjacent fold lines is recorded as the distance between the outer end points of the two adjacent fold lines in the direction vertical to the radius of the annular circle, and the height h of the fold lines is greater than the distance w between the adjacent fold lines so as to ensure that outside light rays cannot directly enter the maze; the end point of the fold line in the labyrinth is an oblique tangent plane, the oblique tangent plane is on the annular circular radius line, the included angle between the oblique tangent plane and the extension line of the fold line is marked as alpha, the alpha is more than or equal to 25 degrees and less than or equal to 55 degrees, and the included angle is preferably 40 degrees so as to reduce the reflection surface and introduce the incident light into the optical barrier, thereby reducing the reflected light; the end point of the fold line outside the labyrinth is also a chamfer surface which faces the outer side of the labyrinth main body so as to block incident light as much as possible. The surface of the optical barrier is a black smooth surface. The structure and the surface can ensure the smoke airflow to come in and go out, and on one hand, the external ambient light can not be directly irradiated to the maze; the other side is the last section of relay reflection of the detection cavity, so that light rays reflected to any optical barrier baffle in the radial direction are guided to the adjacent optical barrier baffle on the surface of the optical barrier baffle and then reflected for multiple times on the surface of the adjacent baffle of the optical barrier without returning to the labyrinth detection cavity.

As shown in fig. 5, the optical barrier diagram-inner-outer double-layer type, which can be understood as a variation of fig. 4, is different from fig. 4 in that the basic shape units are inner and outer arcs, which are arranged at a certain angle with each other, and can also achieve the effect similar to fig. 4. The basic shape unit is two long and short arc lines which are not intersected, the included angle of the extension lines of the line segments formed by the end points of the two arc line segments is defined as beta, and the beta is the acute angle side of the intersection angle. The inner and outer inclined planes are also consistent with those in fig. 4, the inner inclined plane is on the annular circular radius line, the included angle between the inner inclined plane and the extension line of the fold line is marked as alpha, and the values of alpha and beta are consistent with those in fig. 4.

The emission tube comprises one or more emission tubes, the emission tubes are symmetrically arranged, the geometric center of each emission tube is aligned with the central point of the maze main body, and if only one emission tube is arranged, the luminous center of each emission tube is aligned with the central point of the maze main body; the receiving tubes comprise one or more receiving tubes, and the receiving tubes are arranged on an arc taking the center point of the transmitting tube as the center of a circle; the distance from the center point of the transmitting tube to the edge of the photosensitive area of the receiving tube is 1.5 mm-5 mm, preferably 3 mm; after the half power angle is determined, the farther the distance between the LED and the PD is, the smaller the optical intersection area is, conversely, if the optical intersection area needs to be increased after the distance is determined, the half power angle needs to be increased, and the half power angle is too large to be beneficial to aggregate reflection, so that the distance from the center point of the LED to the edge of the PD photosensitive area needs to be controlled within a certain distance. If the LED and the PD are surface-mounted elements which are not packaged into a whole, the edge distance between the LED and the PD is not less than 1mm except for meeting the conditions so as to ensure the mounting requirement. The half-power emission angle of the LED is

To ensure within half power angleMost of light can irradiate on the inner surface of the labyrinth top cover, namely the sectional type reflecting surface.

As shown in FIG. 7, the LED and the PD are arranged in two ways, the distance between PD1 and the geometric center of the maze is d1, the distance between PD2 and the geometric center of the maze is d2, and d1 and d2 can be equal or different, if d1 ≠ d2, then scattered light rays with different scattering angles can be obtained, so that the LED emitting position is fixed, and different PDs can be placed to obtain scattered light rays with different scattering angles. Fig. 7- (a) shows that the receiving tubes and the light emitting tubes are arranged in a straight line, and the centers of the LEDs and the PDs are arranged in a straight line, which is a common layout method of optical devices, the LEDs refer to a combination of LEDs, one or more LEDs are closely arranged, if there is an integrated all-in-one LED device, it is preferred that two LEDs are preferably arranged up and down perpendicular to the above-mentioned straight line if there is a separating device, if there are three LEDs, it is in a delta-shaped layout, if there are four LEDs, it is in a field-shaped layout, and the geometric centers thereof are on the straight line. The distance between PD1 and the geometric center of the maze is d1, the distance between PD2 and the geometric center of the maze is d2, and PD1 and PD2 are positioned on two sides of the LED. The receiving tube and the luminous tube shown in the figure 7- (b) are arranged in a satellite shape, the geometric centers of the PD1, the PD2 and the LED are not in the same straight line, the PD1 and the PD2 are respectively placed on the circular arcs with the radius of d1 and d2 by taking the geometric center of the LED as the center, and more receiving tubes PD can be placed in the same way.

The advantage of fixed LED position is the optical design who makes things convenient for the maze, is favorable to the centralized control light path reflection, depresses the maze height, is favorable to the small-size application occasion of battery package. In addition, the distance from the LED to the PD refers to the distance from the center of the LED to the photosensitive edge of the PD, the center of the LED means the center of the LED light-emitting unit if only one LED exists, and means the geometric center formed by the centers of the LED light-emitting units if a plurality of LEDs exist. The optical device is selected as follows: the transmitting tube selects SFH7016 of OSRAM, and the receiving tube selects SFH2704 of OSRAM.

As shown in fig. 2, the inner surface of the labyrinth top cover is in a form with a high middle periphery and a low middle periphery, so that the possibility of water vapor condensation of power lithium batteries and outdoor power equipment is considered, the labyrinth top cover is defaulted to face the direction of the earth center during installation, the form with the high middle periphery and the low middle periphery is very favorable for dust or condensation accumulated in the labyrinth to fall under the action of gravity and be discharged out of the labyrinth, and particularly in a vehicle-mounted situation, the dust and the condensation can be thrown out of the labyrinth by vibration.

As shown in fig. 6, a groove-shaped structure 16 communicating with the inside of the labyrinth main body is arranged at the joint of the optical barrier 12 and the labyrinth top cover 11, and the width of the groove-shaped structure 16 is narrow inside and wide outside, which is further beneficial to guiding out the dust or the condensation inside to the outside of the labyrinth. The segmented reflective portion may be treated as a hydrophobic surface to further facilitate condensation drainage.

As shown in fig. 1, the main body of the labyrinth is centrosymmetric, and the section parallel to the labyrinth base 13 is circular or elliptical, and the section perpendicular to the labyrinth base 13 is trapezoid-like. Maze main part integral type design adopts the black material of moulding plastics, and the surface finish control of mould is A2 or A3 in order to reduce polishing and manufacturing cost, does benefit to the mechanism and moulds plastics, reduce cost to guarantee the uniformity.

As shown in fig. 1, 2 and 5, the labyrinth base 13 has, on its periphery, an ear region with fixing holes for fixing the labyrinth body together with the circuit board 2 and other machine components 6; the fixed orifices use elasticity bolt 5 or reed fixed, prevent installation or vibrations dislocation to avoid using the ageing fracture problem of mechanism that hard coupling mechanism's such as screw stress problem leads to, a plurality of elasticity bolts 5 or reed mechanisms can pin each other and stress complementary, are favorable to guaranteeing not take place to warp and the displacement at strong vibration and wide temperature environment mechanism. Labyrinth base 13 is the machine component of thickening to guarantee the bulk strength and the fixed fastness of labyrinth, with the service environment of the strong vibration of adaptation driving process.

The main body of the labyrinth is made of materials with wide temperature range and low coefficient of deformation caused by expansion with heat and contraction with cold, so that the strength and the anti-seismic performance of the main body of the labyrinth are ensured in the whole temperature range; as shown in fig. 1-2, the outer surface of the labyrinth cover 11 is a non-planar concave shape, and the outer surface varies with the sectional reflective surface 14 of the inner surface of the labyrinth cover, so as to reduce the problems of injection shrinkage caused by uneven thickness of the material and uneven coefficient of expansion and contraction in use environment. Typical materials are, for example, the TPV (thermoplastic vulcanizate) EnflexVM-564-75A material from ENPLAST/Ravago, which has a higher deformation temperature (>110 ℃), a lower embrittlement temperature (< 50 ℃) and a V0 rating for flame retardancy.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. An ultra-thin labyrinth structure comprises a labyrinth main body, wherein the labyrinth main body comprises a labyrinth base, an optical barrier and a labyrinth top cover, one end of the optical barrier is connected with the labyrinth base, and the other end of the optical barrier is connected with the labyrinth top cover; the bottom of the labyrinth main body is fixedly provided with a circuit board; the inner surface of the labyrinth top cover, the inner surface of the optical barrier and the labyrinth side of the circuit board form a smoke detection cavity;

2. The ultra-thin labyrinth structure as recited in claim 1, wherein: the segmented reflective surface in combination with the inner surface of the optical barrier form at least four stages of reflective surfaces: the first stage reflecting surface is a spherical surface at the center of the labyrinth top cover, the second stage reflecting surface is a variable slope surface, the third stage reflecting surface is a slope surface, the variable slope surface is respectively and smoothly connected with the spherical surface and the slope surface, and the fourth stage reflecting surface is the inner surface of the optical barrier.

3. The ultra-thin labyrinth structure as recited in claim 2, wherein: the radius of the spherical surface is 0.1-0.6 mm, the section curve of the variable slope curved surface is a quadratic curve or a cubic curve, and the slope of the section curve is larger when the section curve is closer to the center of the labyrinth top cover; the slope of the slope surface is 3-10 degrees, and the length of the slope is 1-6 mm; the inner surfaces of the sectional type reflecting surface and the optical barrier are black matte surfaces.

4. The ultra-thin labyrinth structure as recited in claim 1, wherein: the optical barrier is formed by annularly arranging basic units with broken lines on the cross section in a rotary shutter mode, wherein the broken lines are two line segments or two arc line segments which are intersected at one point to form an acute angle, the angle of the acute angle is recorded as beta, and the angle of the beta is more than or equal to 45 degrees and less than 90 degrees;

the height h of the fold lines is recorded as the distance between the perpendicular line of the line segment formed by the intersection point of the fold lines and the two end points of the fold lines, the distance w between the adjacent fold lines is recorded as the distance between the outer end points of the two adjacent fold lines in the direction vertical to the radius of the annular circle, and the height h of the fold lines is greater than the distance w between the adjacent fold lines;

the end point of the folding line in the labyrinth is an oblique cutting plane, the oblique cutting plane is on the annular circular radius line, the included angle between the oblique cutting plane and the extension line of the folding line is marked as alpha, and the alpha is more than or equal to 25 degrees and less than or equal to 55 degrees;

the end point of the fold line outside the labyrinth is also a chamfer, and the chamfer faces the outer side of the labyrinth main body.

5. The ultra-thin labyrinth structure as recited in claim 1, wherein: the emission tube comprises one or more emission tubes, the emission tubes are symmetrically arranged, the geometric center of each emission tube is aligned with the central point of the maze main body, and if only one emission tube is arranged, the luminous center of each emission tube is aligned with the central point of the maze main body; the receiving tubes comprise one or more receiving tubes, and the receiving tubes are arranged on an arc taking the center point of the transmitting tube as the center of a circle; the distance from the central point of the transmitting tube to the edge of the photosensitive area of the receiving tube is 1.5 mm-5 mm.

6. The ultra-thin labyrinth structure as recited in claim 1, wherein: a groove-shaped structure communicated with the inside of the labyrinth main body is arranged at the joint of the optical barrier and the labyrinth top cover, and the width of the groove-shaped structure is narrow inside and wide outside; the segmented reflective surface is provided as a hydrophobic surface.

7. The ultra-thin labyrinth structure as recited in claim 1, wherein: the labyrinth main body is in a central symmetry shape, the section parallel to the labyrinth base is circular or oval, and the section vertical to the labyrinth base is in a trapezoid-like shape; the maze main part adopts black material of moulding plastics, integral type design.

8. The ultra-thin labyrinth structure as recited in claim 1, wherein: an ear-shaped area with a fixing hole extends out of the periphery of the labyrinth base, and the ear-shaped area is used for fixing the labyrinth main body together with the circuit board and other mechanism parts; the fixing holes are fixed by using elastic bolts or reeds.

9. The ultra-thin labyrinth structure as recited in claim 1, wherein: the maze main body is made of materials with wide temperature range and low coefficient of thermal expansion and cold contraction deformation.

10. The ultra-thin labyrinth structure as recited in claim 2, wherein: the outer surface of the labyrinth cap is a non-planar concave shape that varies with the segmented reflective surface of the inner surface of the labyrinth cap.