Contact temperature sensor

Abstract

A contact temperature sensor includes a sensor chip with leads and a housing encapsulating the sensor chip, and the leads extend out of the housing for transmitting the electrical signals of the sensor chip; characterized in that the housing has a lower surface, and when viewed in cross-section, the lower surface includes a lower working surface for contact detection of the surface temperature of a heating body, and a left inclined extension surface and a right inclined extension surface that respectively extend obliquely upward from the lower working surface to the left and right sides. The lower working surface, the left inclined extension surface, and the right inclined extension surface jointly define a trapezoidal heat conduction area, and the sensor chip is arranged and combined into the trapezoidal heat conduction area; according to the above technical solution, compared with the prior art, the beneficial technical effects of the present invention are as follows: by providing a trapezoidal heat conduction area and arranging and combining the sensor chip into the trapezoidal heat conduction area, heat is guided to preferentially enter the heat conduction area and be preferentially transmitted to the sensor chip, improving the response speed and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature detection, and particularly to a contact temperature sensor structure for detecting the surface temperature of an electric coil heating element. Background Art

[0002] In order to ensure that products with heating elements, such as power adapters, transformers, rectifiers, etc. having electric coils, can operate normally and safely, it is generally necessary to control the heating element to operate within a set temperature range to prevent damage to the heating element due to exceeding the set temperature. Common methods for detecting the surface temperature of the heating element include contact detection and non-contact detection. Among them, contact detection is widely welcomed by users due to its simple structure, stable detection, and low cost.

[0003] Common contact temperature sensors on the market are mostly square or cylindrical, usually composed of an induction chip, an insulating layer, and epoxy resin. Insulating sleeves and insulating shells are common insulating layer materials. The induction chip can be first wrapped with an insulating sleeve, or the induction chip can be directly arranged in the insulating shell, and then the induction chip is encapsulated and fixed in the shell by epoxy resin, so that the induction chip and the detected element are insulated from each other. In order to obtain a good electrical safety distance, the thickness of the insulating layer needs to be thick enough to keep a sufficient insulating distance between the induction chip and the detected element. However, for materials with good insulation performance, their thermal conductivity is generally poor. An overly thick insulating layer will be unfavorable for the temperature sensor to quickly and accurately detect the temperature. In order to improve the accuracy of temperature detection, people later used thin insulating materials to encapsulate the induction chip. However, in order to facilitate the installation of the temperature sensor and improve the insulation effect of the electrode leads, a relatively large and thermally conductive outer shell is generally sleeved outside the insulating layer. However, this thermally conductive outer shell will cause a large heat capacity of its own. When the heat of the detected element is transferred to the outer shell, it will quickly spread to other parts of the outer shell element, and then be transferred to the induction chip arranged in the middle of the outer shell. This is not conducive to the response speed of the induction chip, seriously affecting the control accuracy of the controller. In severe cases, it will also cause the heating element to operate beyond the set temperature and cause damage. Summary of the Invention

[0004] In view of the technical problems of inaccurate detection accuracy and slow response speed of existing temperature sensors, the present invention proposes a contact temperature sensor. The temperature sensor includes a sensor chip with leads and a housing encapsulating the sensor chip, and the leads extend out of the housing for transmitting the electrical signals of the sensor chip; characterized in that, the housing has a lower surface, and in terms of cross-section, the lower surface includes a lower working surface for contact detection of the surface temperature of the heating body and a left inclined extension surface and a right inclined extension surface that respectively extend obliquely upward from the lower working surface to the left and right sides, and the lower working surface, the left inclined extension surface and the right inclined extension surface together define a trapezoidal heat conduction area, and the sensor chip is arranged and combined into the trapezoidal heat conduction area.

[0005] Wherein, the leads refer to the electrical signal connection lines connected to the sensor chip and used for transmitting the electrical signals of the sensor chip. Part of the leads connected to the sensor chip are encapsulated in the housing together with the sensor chip. In order to transmit electrical signals outward, the leads also include an exposed part exposed outside the housing; in order to protect the leads, a lead sleeve is sleeved outside the leads. The lead sleeve can be sleeved only on the exposed part of the leads outside the housing, or can be sleeved both on the exposed part of the leads outside the housing and on the part of the leads encapsulated in the housing; further, in order to prevent the leads exposed outside the housing from being damaged by friction during use, an outer lead sleeve can be added outside the lead sleeve.

[0006] Wherein, the lower surface, in addition to including the working surface provided on the housing for contacting the surface of the heating body, also includes the left inclined extension surface and the right inclined extension surface that are respectively disposed on both sides of the lower working surface and extend obliquely upward; in terms of cross-section, both the left inclined extension surface and the right inclined extension surface are inclined surfaces, which is equivalent to cutting off part of the materials on both sides of the lower left corner and the lower right corner of the housing, reducing the transfer of heat transferred from the surface of the heating body to both sides of the lower left corner and the lower right corner of the housing, and enabling the heat to be transferred upward along the housing between the left inclined extension surface and the right inclined extension surface. The left inclined extension surface and the right inclined extension surface themselves can be linear or slightly arc-shaped in terms of cross-section.

[0007] Among them, the heat conduction area refers to a trapezoidal space area jointly defined by the lower working surface, the left inclined extension surface, and the right inclined extension surface. The heat conduction area can be used to transfer heat. Under the guidance of the lower working surface, the left inclined extension surface, and the right inclined extension surface, the heat of the heating element will first pass through the heat conduction area and then be transferred upward to other parts of the housing. In addition, the heat conduction area is generally trapezoidal with a wider upper part and a narrower lower part, and the heat of the heating element follows the shape of the heat conduction area to form an upward and diffused transmission path.

[0008] Among them, the sensor chip arrangement is combined with the trapezoidal heat conduction area to define the position of the sensor chip arrangement. At least part of the sensor chip extends into or contacts the heat conduction area, allowing the heat radiated from the heating element to be transferred to the sensor chip along the shortest possible route.

[0009] According to the above technical solution, compared with the prior art, the beneficial technical effects of the present invention are as follows: By setting a trapezoidal heat conduction area and combining the sensor chip arrangement with the trapezoidal heat conduction area, the heat is guided to enter the heat conduction area first and is preferentially transferred to the sensor chip, improving the response speed and accuracy.

[0010] To further improve the response speed of the sensor chip, the left inclined extension surface or / and the right inclined extension surface respectively have a first-level step. The step is provided on the left inclined extension surface or the right inclined extension surface, and includes a step plane that is substantially parallel to the lower working surface and faces the surface of the heating element to be detected, and a step side surface that extends obliquely downward from the step plane towards the lower working surface. The step setting method includes the following two cases. The first case is that the step is only provided on the surface of one of the left inclined extension surface and the right inclined extension surface. The second case is that the step is simultaneously provided on the left inclined extension surface and the right inclined extension surface respectively. By providing the step on the left inclined extension surface or / and the right inclined extension surface, a top trapezoidal bump is formed at the end of the trapezoidal heat conduction area close to the lower working surface. In this way, while further reducing the material used for the housing, the heat of the heating element is first transferred from the lower working surface to the top trapezoidal bump of the heat conduction area, and then the top trapezoidal bump transfers the heat to the sensor chip close to the heat conduction area in a more concentrated direction, thereby improving the detection response speed of the sensor chip.

[0011] To facilitate the installation and fixation of the housing, the housing further has an upper surface that is parallel to the lower working surface. In this way, by applying a pressing force to the upper surface, the housing can be conveniently pressed and fixed on the surface of the heating element, and at the same time, the lower working surface of the housing can better fit the surface of the heating element, which is beneficial to heat transfer.

[0012] Furthermore, the width of the upper surface is equal to the width of the lower surface. Herein, the width of the lower surface refers to the total width of the projections of the lower working surface, the left inclined extension surface, and the right inclined extension surface onto the plane where the lower working surface is located. A larger width of the upper surface is beneficial for cooperating with other fastening parts to press and fix the housing.

[0013] Furthermore, to reduce the heat capacity of the housing, the width of the housing is greater than its height, making it flat. Under the condition of ensuring sufficient strength and safety insulation distance, minimizing the material used for the housing helps reduce the heat capacity of the housing. In this way, it is beneficial to ensure the detection response speed of the sensor chip.

[0014] To facilitate the installation of the sensor chip, furthermore, the housing is in a long strip shape with a closed front end, and the lead extends from the rear end of the housing. The sensor chip is arranged near the front end of the housing. The long-strip-shaped housing can well fix and protect the sensor chip and part of the leads connected to the sensor chip, and the closed front end of the housing can position the sensor chip near the front end of the housing. The beneficial effects are as follows: First, it is beneficial to the installation of the sensor chip; Second, it well fixes the position of the sensor chip, which is beneficial to making the sensor chip close to the desired temperature measurement point when fixing the housing; Third, extending the lead from the rear end of the housing can keep the lead away from the temperature-higher temperature measurement point, which is beneficial to protecting the lead.

[0015] Furthermore, a positioning plate is provided at the rear end of the housing, and the lead passes through the positioning plate and extends out and is positioned on the positioning plate. In this way, the positioning plate provided at the rear end of the housing not only facilitates the positioning of the housing during installation but also can be used to fix the lead extending from the rear end of the housing to keep the lead away from the surface of the heating element and reduce the friction caused by the swing of the lead.

[0016] Furthermore, the housing is filled with a heat-conducting material. The heat-conducting material is beneficial to quickly transfer the heat transferred by the housing to the sensor chip, greatly improving the response speed of the sensor chip.

[0017] Due to the above characteristics and advantages of the present invention, it can be applied to a contact temperature sensor. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram in the axonometric direction of a contact temperature sensor applying the technical solution of the present invention;

[0019] Figure 2 is a schematic structural diagram in the front view direction of a contact temperature sensor applying the technical solution of the present invention, showing the structural relationship between the sensor chip and the housing;

[0020] Figure 3 is Figure 2 a schematic cross-sectional structural diagram in the A-A direction in, showing the structure of the housing and the schematic diagram of the heat transfer path;

[0021] Figure 4 is Figure 3 a partial enlarged view of part M in, showing the dimensional relationship diagram of the heat conduction area structure. Detailed Embodiment

[0022] The structure of a contact temperature sensor applying the technical solution of the present invention will be further described below with reference to the drawings.

[0023] The present invention provides a contact temperature sensor, such as Figure 1 and Figure 2As shown, generally, the contact temperature sensor is arranged on the surface of the heating element 1. The contact temperature sensor senses the heat transferred from the surface of the heating element 1 and converts it into an electrical signal representing different temperature values, and conducts it outward through the lead 3. The contact temperature sensor includes a sensor chip 4 with a lead 3 and a housing 2 encapsulating the sensor chip 4. Among them, the sensor chip 4 includes a hermetically sealed chip body 41 and electrode pins 42, and the electrode pins 42 are connected to the lead 3. Among them, the housing 2 is a thin housing made of engineering plastics with high temperature resistance, good electrical insulation and good heat conduction ability. The encapsulation methods of the housing 2 and the sensor chip 4 generally include the following two types: The first is the integral injection molding method, in which the sensor chip 4 and the housing 2 are integrally injection molded, and the housing 2 can completely and hermetically wrap the sensor chip 4; The second is to first injection mold the housing 2, and a cavity for accommodating the sensor chip 4 is provided on the housing 2. The sensor chip 4 is first placed into the cavity, and then a packaging material (such as epoxy resin glue) is poured into the cavity for sealing and curing. The lead 3 extends out of the housing 2 to transmit the electrical signal of the sensor chip 4. Since the lead 3 is connected to the sensor chip 4, part of the lead 3 is encapsulated in the housing 2 together with the sensor chip 4. And the housing 2 or the packaging material has good insulation performance, so the connecting electrode part of the lead 3 and the sensor chip 4 can be directly insulated and isolated through the packaging material when there is a sufficient safety distance. However, in order to ensure that the electrical signal can be normally transmitted through the lead 3, a lead sleeve 31 is sleeved on the exposed part of the lead 3 outside the housing 2, or a lead sleeve 31 is sleeved on both the exposed part of the lead 3 outside the housing 2 and the part of the lead 3 encapsulated in the housing 2. In this way, the lead 3 can be well insulated and isolated, and the effectiveness of signal transmission can be guaranteed.

[0024] For the convenience of installing the sensor chip 4, further, the housing 2 is in a long strip shape with its front end closed, the lead 3 extends from the rear end of the housing 2, and the sensor chip 4 is arranged near the front end of the housing 2. Among them, the long-strip-shaped housing 2 can well fix and protect the sensor chip 4 and part of the leads 3 connected to the sensor chip 4, and the closed front end of the housing 2 can enable the sensor chip 4 to be positioned near the front end of the housing 2. On the other hand, extending the lead 3 from the rear end of the housing 2 can keep the lead 3 away from the temperature measurement point with a higher temperature, which is beneficial to protecting the lead 3. Further, friction is likely to occur between the lead 3 and the rear end of the housing 2, or the lead 3 is also likely to rub against the fixing parts during fixation. Thus, an outer lead sleeve 32 can be added outside the lead 3 to protect the lead 3.

[0025] As Figures 1 to 4 shown, the housing 2 has a lower surface 29. From a cross-sectional view, the lower surface 29 includes a lower working surface 21 for contact detection of the surface temperature of the heating body 1, and a left inclined extension surface 22 and a right inclined extension surface 23 that respectively extend obliquely upward from the lower working surface 21 to the left and right sides. Among them, the lower working surface 21 is the surface in contact with the surface of the heating body 1, and the heat of the heating body 1 is transmitted upward through the lower working surface 21. This heat transfer structure is simple and stable, which is beneficial to heat transfer. And due to the provision of the left inclined extension surface 22 and the right inclined extension surface 23, this is equivalent to cutting off part of the materials on both the lower left and lower right corners of the housing 2, which reduces the heat transferred from the surface of the heating body 1 to the left and right sides of the housing 2, making the heat mainly transfer upward along the housing between the left inclined extension surface 22 and the right inclined extension surface 23. In this way, the heat transfer path is shortened, which is beneficial to controlling the heat transfer in a specified direction. The lower working surface 21, the left inclined extension surface 22 and the right inclined extension surface 23 together define a trapezoidal heat conduction area 24. The heat conduction area 24 is a spatial area defined by the lower working surface 21, the left inclined extension surface 22 and the right inclined extension surface 23. This spatial area can transfer heat. The lower working surface 21 is in contact with the surface of the heating body 1, and the heat of the heating body 1 will first be transferred to the heat conduction area 24 and then upward to other parts of the housing 2. As Figure 3As shown, the heat conduction region 24 is generally trapezoidal with a wider top and a narrower bottom. The heat of the heating element 1 follows the shape of the heat conduction region to form a diffusion-like upward transfer path. Further, the sensor chip 4 is arranged and combined with the trapezoidal heat conduction region 24, so that the heat transferred from the heating element 1 is directly transferred to the sensor chip 4 through the heat conduction region 24, shortening the heat transfer distance between the sensor chip 4 and the heating element 1, thereby greatly improving the response speed of the sensor chip 4.

[0026] In order to further improve the response speed of the sensor chip 4, the left inclined extension surface 22 or / and the right inclined extension surface 23 respectively have a first-level step (221, 231). The setting of the step (221, 231) can include the following two situations. The first is that the step 221 is only set on the left inclined extension surface 22, or the step 231 is only set on the surface of the right inclined extension surface 23; the second is that the steps (221, 231) are respectively set on the left inclined extension surface 22 and the right inclined extension surface 23 at the same time. As Figure 3 shown, in this embodiment, the step 221 provided on the left inclined extension surface 22 includes a left step plane 2211 that is substantially parallel to the lower working surface 21 and faces the detected heating element 1, and a left step side surface 2212 that extends obliquely downward from the left step plane 2211 to the lower working surface 21. The left step side surface 2212 is substantially parallel to the left inclined extension surface 22; the step 231 provided on the right inclined extension surface 23 includes a right step plane 2311 that is substantially parallel to the lower working surface 21 and faces the detected heating element 1, and a right step side surface 2312 that extends obliquely downward from the right step plane 2311 to the lower working surface 21. The right step side surface 2312 is substantially parallel to the left inclined extension surface 23. Of course, in other embodiments, the setting shape of the step (221, 231) is diverse. The step (221, 231) makes the trapezoidal heat conduction region 24 in a convex shape and forms a top trapezoidal bump at one end of the lower working surface 21. In this way, the heat from the heating element 1 is first transferred to the top trapezoidal bump of the heat conduction region 24 through the lower working surface 21, and then the top trapezoidal bump transfers the heat to the sensor chip 4 close to the heat conduction region 24 through a more concentrated transfer path, thereby improving the detection response speed of the sensor chip 4.

[0027] To facilitate the fixation of the housing 2, the housing 2 further has an upper surface 25, and the upper surface 25 is parallel to the lower working surface 21. In this way, by applying a pressing force to the upper surface 25, the housing 2 can be pressed against the heating element 1, so that the lower working surface 21 of the housing 2 can better fit the surface of the heating element 1. Further, the width of the upper surface 25 is equal to the width of the lower surface 29. Wherein, the width of the lower surface 29 refers to the total width of the projections of the lower working surface 21, the left inclined extension surface 22, and the right inclined extension surface 23 on the plane where the lower working surface 21 is located. A larger width of the upper surface 25 is beneficial for other fastening parts to press and fix the housing 2. In one embodiment, the housing 2 is pressed against the surface of the heating element 1 by arranging a pressing spring or a spring piece on the upper surface 25.

[0028] Further, to reduce the heat capacity of the housing 2, the width of the housing 2 is greater than the height, so that it is flat. Under the condition of ensuring sufficient strength and safety insulation distance, the housing 2 uses as little material as possible, and making the housing 2 form a thin shell is beneficial to reducing the heat capacity of the housing 2. In this way, it is beneficial to ensure the detection response speed of the sensor chip 4.

[0029] Further, a positioning plate 26 is also provided at the rear end of the housing 2, and the lead 3 passes through the positioning plate 26 and extends out and is positioned on the positioning plate 26. In this way, the positioning plate 26 provided at the rear end of the housing 2 can not only be used to position or fix the housing 2, but also can be used to fix the lead 3 extending from the rear end of the housing 2 to keep the lead 3 away from the surface of the heating element 1 and reduce the friction between the lead 3 and the positioning plate 26.

[0030] Further, the housing 2 is filled with a heat-conducting material. The heat-conducting material is beneficial to quickly transfer the heat transferred by the housing 2 to the sensor chip 4, greatly improving the response speed of the sensor chip 4.

[0031] To make the housing 2 form a thinner shell and enable the sensor chip 4 to have a sufficient insulation safety distance, further improve the response speed and measurement accuracy of the temperature sensor, as Figure 4 shown, in this embodiment, the following optimization design is made for the position dimension relationship between the convex heat conduction area 24 on the housing and the sensor chip 4:

[0032] 1) The package size of the sensor chip 4 (including the encapsulation resin) is a;

[0033] 2) Relationship between the width b of the contact between the lower working surface 21 and the surface of the heating element 1 and the package size a of the sensor chip 4: 0.5a < b < 1.5a;

[0034] 3) Relationship between the vertical shortest distance h between the lower working surface 21 and the sensor chip 4 and the package size a of the sensor chip 4: 0.3 mm < h < 1 / 3a;

[0035] 4) The vertical shortest distance between the left step side surface 2212 and the sensor chip 4 is h1, and the vertical shortest distance between the right step side surface 2312 and the sensor chip 4 is h2. Relationship between h1, h2 and h: 0.5h < (h1 or h2) < 2h;

[0036] 5) Relationship between the distance c between the lower working surface 21 and the left step plane 2211 or the right step plane 2311 and h: 0.5h < c < 2h;

[0037] 6) Relationship between the width d of the left step plane 2211 or the right step plane 2311 and b: 0

Claims

1. Contact temperature sensor, comprising a sensor chip with leads and a housing encapsulating the sensor chip, the leads extending out of the housing for transmitting the electrical signals of the sensor chip; characterized in that, The housing has a lower surface, which, when viewed in cross-section, includes a lower working surface for contact detection of the surface temperature of the heating element, and a left inclined extension surface and a right inclined extension surface that extend obliquely upward from the lower working surface towards the left and right sides respectively. The lower working surface, the left inclined extension surface, and the right inclined extension surface together define a trapezoidal heat conduction region, and the sensor chip is arranged and integrated into the trapezoidal heat conduction region; The left inclined extension surface and / or the right inclined extension surface each have a first-level step, and a top trapezoidal bump is formed at one end of the trapezoidal heat conduction region close to the lower working surface.

2. The contact temperature sensor according to claim 1, characterized in that The housing also has an upper surface, which is parallel to the lower working surface.

3. The contact temperature sensor according to claim 2, characterized in that, The width of the upper surface is equal to the width of the lower surface.

4. The contact temperature sensor according to claim 2, characterized in that, The width of the housing is greater than the height, so it is flat.

5. The contact temperature sensor according to any one of claims 1 to 4, characterized in that, The housing is in a long strip shape, its front end is closed, the lead extends out from the rear end of the housing, and the sensor chip is arranged at a position close to the front end of the housing.

6. The contact temperature sensor according to claim 5, wherein A positioning plate is further provided at the rear end of the housing, and the lead passes through the positioning plate and is positioned on the positioning plate.

7. The contact temperature sensor according to any one of claims 1 to 4, characterized in that, The housing is filled with a heat-conducting material.

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