A temperature sensing detector and a design method thereof

Abstract

The invention relates to a temperature sensing detector and a design method thereof, wherein the temperature sensing detector comprises a shell and a thermistor fixed in the shell; a plurality of longitudinal guide plates are fixed in the shell; the plurality of guide plates are radially distributed with the thermistor as the center; a plurality of through holes are opened on the side of the guide plates; a plurality of air vents are opened on the side wall of the shell; the number of the air vents is equal to the number of the guide plates; the plurality of air vents and the plurality of guide plates are arranged at intervals; when working, the airflow around the temperature sensing detector enters the shell through the air vents, and then reaches the thermistor under the guidance of the guide plates, and the thermistor performs temperature sensing, thereby realizing fire detection; the arrangement of the guide plates enables the airflow to reach the thermistor faster and more accurately, thereby improving the accuracy and sensitivity of the temperature sensing of the temperature sensing detector.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature sensing detectors, and more specifically, to a temperature sensing detector and a design method thereof. Background Art

[0002] A temperature detector, referred to as a temperature sensor, is a detection device that mainly uses a thermistor to detect fire. When the temperature of the surrounding environment changes, the thermistor will undergo physical changes and convert the temperature signal into a corresponding electrical signal, thereby achieving fire detection.

[0003] In order to prevent its core component, the thermistor, from being directly damaged by external human and material forces, existing temperature detectors have a protective structure set around the thermistor to protect it. However, the setting of the protective structure makes the air flow around the thermistor worse, resulting in poor accuracy and sensitivity of the temperature sensing by the temperature detector. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a temperature sensing detector and a design method of the temperature sensing detector in view of the above-mentioned defects of the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] On the one hand, the present invention provides a temperature sensing detector, comprising a shell and a thermistor fixed in the shell; wherein, a plurality of longitudinal guide plates are fixed in the shell; the plurality of guide plates are radially distributed with the thermistor as the center; a plurality of through holes are opened on the side of the guide plate; a plurality of ventilation holes are opened on the side wall of the shell; the number of the ventilation holes is equal to the number of the guide plates; the plurality of ventilation holes and the plurality of guide plates are arranged at intervals.

[0007] The temperature sensing detector described in the present invention, wherein the plurality of through holes are arranged in an orderly manner on the guide plate.

[0008] The temperature sensing detector of the present invention, wherein the maximum size of the through hole is no greater than 5 mm.

[0009] In the temperature sensing detector of the present invention, the through hole is in a polygonal, circular or elliptical shape.

[0010] In the temperature sensing detector of the present invention, the porosity of the guide plate is 30%-80%; the porosity is equal to the sum of the cross-sectional areas of the plurality of through holes divided by the side area of ​​the guide plate.

[0011] In the temperature sensing detector of the present invention, the thickness of the guide plate increases gradually from an end close to the thermistor to an end away from the thermistor.

[0012] In the temperature sensing detector described in the present invention, the cross section of the guide plate is in the shape of an isosceles trapezoid.

[0013] On the other hand, the present invention provides a method for designing a temperature sensing detector, based on the aforementioned temperature sensing detector, which includes the following steps:

[0014] Step 1: Arrange a plurality of guide plates on the housing;

[0015] Step 2: Conduct a standard temperature chamber test to test the azimuth performance;

[0016] Step 3: Adjust the position of the guide vanes according to the test results of the standard temperature box test. The adjustment principle is: increase the distance between the two guide vanes located at the position with low temperature response, and reduce the distance between the two guide vanes located at the position with high temperature response;

[0017] Step 4: Repeat steps 2 and 3 until the positional performance of the temperature detector in each position is consistent;

[0018] Step 5: Design the shape, position and number of the through holes opened on the guide plate;

[0019] Step 6: Design the matching structure of the guide vane to facilitate the assembly of the guide vane.

[0020] The beneficial effects of the present invention are as follows: when working, the airflow around the temperature sensor enters the shell through the vent hole, and then reaches the thermistor under the guidance of the guide plate, and the thermistor senses the temperature, thereby realizing fire detection; the setting of the guide plate allows the airflow to reach the thermistor faster and more accurately, thereby improving the accuracy and sensitivity of the temperature sensing of the temperature sensor; the setting of the through hole, firstly, provides more channels for the flow of airflow, reduces the flow modulus, reduces the flow resistance, thereby increasing the flow rate of gas reaching the thermistor, and secondly, reduces the contact area between the airflow and the guide plate, thereby reducing heat loss. The above two points allow more airflow to reach the thermistor quickly and accurately with less heat loss, thereby further improving the accuracy and sensitivity of the temperature sensing of the temperature sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work:

[0022] Figure 1 is a schematic structural diagram of a temperature sensing detector according to a first embodiment of the present invention;

[0023] Figure 2 yes Figure 1 AA section view;

[0024] Figure 3 is a schematic structural diagram of a guide plate of a temperature sensing detector according to a first embodiment of the present invention;

[0025] Figure 4 It is a flow chart of a method for designing a temperature sensing detector according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0027] Embodiment 1

[0028] The structural diagram of the temperature sensing detector according to the first embodiment of the present invention is as follows: Figure 1 See also Figures 2 to 3 ; It includes a shell 1 and a thermistor 3 fixed in the shell 1; a plurality of longitudinal guide plates 2 are fixed in the shell 1; the plurality of guide plates 2 are radially distributed with the thermistor 3 as the center; a plurality of through holes 5 are opened on the side of the guide plate 2; a plurality of ventilation holes 4 are opened on the side wall of the shell 1; the number of ventilation holes 4 is equal to the number of guide plates 2; the plurality of ventilation holes 4 and the plurality of guide plates 2 are arranged at intervals.

[0029] During operation, the airflow around the temperature detector enters the housing 1 through the vent 4, and then reaches the thermistor 3 under the guidance of the guide plate 2, and the thermistor 3 senses the temperature, thereby realizing fire detection; the setting of the guide plate 2 allows the airflow to reach the thermistor 3 faster and more accurately, thereby improving the accuracy and sensitivity of the temperature sensing of the temperature detector; the setting of the through hole 5, firstly, provides more channels for the flow of airflow, reduces the flow modulus, reduces the flow resistance, thereby increasing the flow rate of gas reaching the thermistor 3, and secondly, reduces the contact area between the airflow and the guide plate 2, thereby reducing heat loss. The above two points allow more airflow to reach the thermistor 3 quickly and accurately with less heat loss, further improving the accuracy and sensitivity of the temperature sensing of the temperature detector.

[0030] In order to facilitate understanding of the beneficial effects of opening through holes, the following explanations are given:

[0031] 1. Regarding the point that “the setting of through holes provides more channels for the flow of air, thereby increasing the flow of gas reaching the thermistor”

[0032] The Bernoulli equation considering the viscosity of the fluid is:

[0033]

[0034] Where λ is the friction coefficient, l is the flow length, d is the hydraulic diameter and A is the flow area, χ is the wetted perimeter, which refers to the perimeter length of the contact between the fluid and the solid wall on the flow section, u is the fluid velocity, and ξ is the local resistance, which has a small impact in this patent and is therefore not considered.

[0035] It can be simplified as:

[0036]

[0037] in,

[0038] And since the flow modulus K is:

[0039]

[0040] and

[0041] Among them, V is the flow rate, A is the flow area;

[0042] in addition,

[0043]

[0044] so,

[0045]

[0046] so,

[0047]

[0048] Then, before the guide plate is provided with through holes, there are:

[0049]

[0050] After the guide plate is provided with through holes, there are:

[0051]

[0052] Among them, the symbols without * represent the parameters before the through holes are set, and the symbols with * represent the parameters after the guide plate is set with through holes. For example, the flow modulus before the guide plate is set with through holes is K 内, the flow modulus after the guide plate is opened with a through hole is

[0053] If the flow modulus of multiple through holes is recorded as K 1 ,……,K n , and the fluid channel after the guide plate is opened with a through hole is approximated as the parallel connection of the main channel and multiple secondary channels. The main channel is the area between two adjacent guide plates, and the secondary channel is the internal area of ​​the through hole. It can be seen that the flow modulus of the main channel is the flow modulus K before the guide plate is not provided with a through hole 内 , then:

[0054]

[0055] We can get:

[0056]

[0057] Combining formulas and You can get:

[0058] exist In the case of

[0059]

[0060] Therefore, the provision of the through hole increases the flow rate of gas reaching the thermistor.

[0061] Second, regarding the point that "the setting of the through hole reduces the contact area between the airflow and the guide plate, thereby reducing heat loss,"

[0062] 1. When the airflow flows inside the shell, it will contact the guide vane, and its heat will be transferred to the guide vane, resulting in heat loss;

[0063] 2. According to the flow distribution principle of the fluid, the fluid will flow to the part / area with smaller resistance. When the air flows inside the shell of the temperature detector, the flow resistance of the air flowing in the through hole is greater than that flowing in the area between two adjacent guide plates. Therefore, in the actual flow process, most of the air will flow in the area between two adjacent guide plates, so the heat loss of the airflow mainly comes from the contact with the side of the guide plate;

[0064] 3. The Fourier formula for heat conduction is: Among them, Φ is the heat conduction, λ is the thermal conductivity, Δt is the temperature difference, δ is the thickness of the conductive medium, and A is the thermal contact area.

[0065] From the formula, we can see that heat conduction is proportional to the contact area. The opening of through holes reduces the contact area, thus reducing heat loss.

[0066] Preferably, a plurality of through holes 5 are arranged in an orderly manner on the guide plate 3 to facilitate processing.

[0067] Preferably, the maximum size of the through hole 5 is no greater than 5 mm; the flow guiding effect is good, which is beneficial to reduce heat loss and further improve the accuracy and sensitivity of the temperature sensing detector.

[0068] Preferably, the shape of the through hole 5 is polygonal, circular or elliptical, which is convenient for processing.

[0069] It should be noted that the shape of the through hole 5 is not limited to the above-mentioned shapes, and the cross section of the through hole 5 only needs to be a closed outline, for example, it can also be a shape surrounded by straight lines and arcuate sides.

[0070] Preferably, the porosity of the guide plate 2 is 30%-80%; the porosity is equal to the sum of the cross-sectional areas of the plurality of through holes 5 divided by the side area of ​​the guide plate 2; the guide effect is good, which is beneficial to reduce heat loss and further improve the accuracy and sensitivity of the temperature sensing detector.

[0071] Preferably, the thickness of the guide plate 2 increases gradually from the end close to the thermistor 3 to the end far away from the thermistor 3 ; the guide effect is good.

[0072] Preferably, the cross section of the guide plate 2 is in the shape of an isosceles trapezoid, which has a good guide effect.

[0073] Further preferably, the included angle between the two sides of the cross section of the guide vane is 0.5° to 3°.

[0074] As an example, the longitudinal section of the guide plate 2 is a right-angled trapezoid, and the lengths of its three right-angled sides are 28 mm, 14.25 mm, and 22 mm, respectively. The longitudinal section area is calculated to be 356.25 mm. 2 There are 126 through holes 5 on it. The shape of the through hole 5 is a right-angled trapezoid. The lengths of its three right-angled sides are 1.5mm, 1mm, and 1mm respectively. It can be calculated that the flow area of ​​each through hole 5 is 1.25mm 2 , the sum of the cross-sectional areas of the 126 through holes 5 is 157.5 mm 2 The porosity is 44.2%. Experiments have shown that the gas flow rate of the temperature-sensing detector equipped with such a guide plate 2 increases by 30%. When the temperature of the temperature box rises to 85°C at a heating rate of 30°C / min, the detector response temperature is about 70°C, and the temperature response data is improved by about 10%.

[0075] Embodiment 2

[0076] The flow chart of the design method of the temperature sensing detector of the second embodiment of the present invention is as follows: Figure 4 As shown, the following steps are included:

[0077] Step S101: arranging a plurality of guide vanes on the housing;

[0078] Step S102: Perform a standard temperature chamber test to test the orientation performance;

[0079] Step S103: adjusting the position of the guide vanes according to the test results of the standard temperature box test, the adjustment principle is: increasing the distance between the two guide vanes located at the position with low temperature response, and decreasing the distance between the two guide vanes located at the position with high temperature response;

[0080] Step S104: repeating steps 2 and 3 until the azimuth performance of the temperature sensor in each direction is consistent;

[0081] Step S105: designing the shape, position, and number of through holes opened on the guide plate;

[0082] Step S106: designing the matching structure of the guide vane to facilitate the assembly of the guide vane.

[0083] The temperature detector designed according to this design method has excellent accuracy and sensitivity in sensing temperature.

[0084] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A temperature detector, comprising a housing and a thermistor fixed in the housing; characterized in that: A plurality of longitudinal guide plates are fixedly arranged in the shell; the plurality of guide plates are radially distributed with the thermistor as the center; a plurality of through holes are opened on the side of the guide plate; a plurality of ventilation holes are opened on the side wall of the shell; the number of the ventilation holes is equal to the number of the guide plates; the plurality of ventilation holes and the plurality of guide plates are arranged at intervals, and the porosity of the guide plates is 30%-80%; the porosity is equal to the sum of the cross-sectional areas of the plurality of through holes divided by the side area of ​​the guide plates, and the thickness of the guide plates increases from the end close to the thermistor to the end away from the thermistor.

2. The temperature detector according to claim 1, characterized in that: The plurality of through holes are arranged in an orderly manner on the guide plate.

3. The temperature detector according to claim 1, characterized in that: The maximum size of the through hole is no greater than 5 mm.

4. The temperature detector according to claim 1, characterized in that: The through hole is in a polygonal, circular or elliptical shape.

5. The temperature detector according to claim 1, characterized in that: The cross section of the guide plate is in the shape of an isosceles trapezoid.

6. A method for designing a temperature detector, based on the temperature detector according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Arrange a plurality of guide vanes on the housing; Step 2: Conduct a standard temperature chamber test to test the azimuth performance; Step 3: Adjust the position of the guide vanes according to the test results of the standard temperature box test. The adjustment principle is: increase the distance between the two guide vanes located at the position with low temperature response, and reduce the distance between the two guide vanes located at the position with high temperature response; Step 4: Repeat steps 2 and 3 until the positional performance of the temperature detector in each position is consistent; Step 5: Design the shape, position and number of the through holes opened on the guide plate; Step 6: Design the matching structure of the guide vane to facilitate the assembly of the guide vane.

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