Thermal mass flow sensor

Abstract

The utility model is applicable to the technical field of sensors, and provides a thermal mass flow sensor, which comprises a shell, a temperature sensor and a temperature sensor, the heat insulation structure is arranged on the shell, the heat insulation structure is used for defining a heat insulation area on the shell and an external area located outside the heat insulation area, and at least part of the heat insulation area is separated from the external area; at least part of the detection assembly is accommodated in the heat insulation area; according to the thermal mass flow sensor provided by the invention, the thermal insulation area is enclosed on the shell through the thermal insulation structure, and part of the detection assembly is accommodated in the thermal insulation area, so that the negative influence of an external heat source on the precision of the thermal mass flow sensor is reduced; meanwhile, heat generated by part of the detection assemblies located in the heat insulation area can also be evenly distributed in the heat insulation area so as to reduce the temperature gradient in the heat insulation area, and therefore the negative influence on the precision of the thermal mass flow sensor can be further reduced.

Description

Technical Field

[0001] The present application belongs to the field of sensor technology, and in particular relates to a thermal mass flow sensor. Background Art

[0002] The thermistors in current thermal mass flow sensors are easily affected by external and internal heat sources, resulting in uneven temperature and temperature gradient in the area near the thermistor. The existence of temperature gradient can easily interfere with the accuracy of the thermistor, thereby easily leading to reduced accuracy of the thermal mass flow sensor. Utility Model Content

[0003] In view of the above problems, the present application provides a thermal mass flow sensor, which can reduce the temperature gradient near the thermistor and improve the measurement accuracy of the thermal mass flow sensor.

[0004] The present application provides a thermal mass flow sensor, comprising:

[0005] a housing, wherein a detection component is disposed in the housing;

[0006] A heat insulation structure is provided on the outer shell, the heat insulation structure is used to enclose a heat insulation area and an external area outside the heat insulation area on the outer shell, and at least a part of the heat insulation area is isolated from the external area;

[0007] At least a portion of the detection assembly is housed in the thermally insulating region.

[0008] In the technical solution of the present embodiment, a heat-insulating area is enclosed on the outer shell by a heat-insulating structure, and part of the detection component is accommodated in the heat-insulating area to reduce the interference of external heat sources on part of the detection component located in the heat-insulating area, thereby reducing the negative impact of external heat sources on the accuracy of the thermal mass flow sensor; at the same time, the heat generated by part of the detection component located in the heat-insulating area can also be more evenly distributed in the heat-insulating area to reduce the temperature gradient in the heat-insulating area, thereby further reducing the negative impact on the accuracy of the thermal mass flow sensor.

[0009] In some embodiments, the thermal insulation structure includes a partition groove opened in the outer shell.

[0010] The technical solution of this embodiment provides some specific structures of the heat insulation structure, which separates the heat insulation area and the external area on the outer shell through partition grooves, so that the partition grooves can separate the heat insulation area and the external area through air, thereby reducing the interference of the heat in the external area on the detection components in the heat insulation area, thereby improving the accuracy of the thermal mass flow sensor.

[0011] In some embodiments, the thermal insulation structure further includes a thermal insulation material filled in the partition groove.

[0012] The technical solution of this embodiment further provides some specific structures of the thermal insulation structure, in which thermal insulation material is filled in the partition groove to further separate the external area and the thermal insulation area through the thermal insulation material, thereby reducing the interference of the heat in the external area on the detection components in the thermal insulation area; at the same time, part of the side walls corresponding to the thermal insulation area can also be connected to part of the side walls corresponding to the external area through the thermal insulation material, so that the thermal insulation structure can enclose the thermal insulation area as a closed area, thereby better reducing the interference of the heat in the external area on the detection components in the thermal insulation area.

[0013] In some embodiments, the thermal conductivity of the material of the housing is greater than or equal to 10 W / (m·k), and the thermal conductivity of the insulation material is less than or equal to 5 W / (m·k).

[0014] In the technical solution of this embodiment, the thermal conductivity of the material of the outer shell is made larger, so that the material of the thermal insulation area can also have a larger thermal conductivity, so that the temperature in the thermal insulation area can be conducted faster and evenly distributed, thereby reducing the temperature gradient in the thermal insulation area; at the same time, the thermal conductivity of the thermal insulation material is made smaller to reduce the interference of external heat sources and heat in the external area on the detection components in the thermal insulation area.

[0015] In some embodiments, the thermal insulation structure is used to separate the thermal insulation area from the external area, and the detection component is accommodated in the thermal insulation area.

[0016] In the technical solution of this embodiment, the insulation area is completely separated from the external area by an insulation structure, and the detection component is completely contained in the insulation area to reduce the interference of external heat sources and heat in the external area on the detection component, thereby improving the accuracy of the thermal mass flow sensor.

[0017] In some embodiments, the thermal insulation region includes at least two sub-regions, and the sub-regions are used to accommodate parts of the detection component.

[0018] In the technical solution of this embodiment, the heat-insulating area includes at least two sub-areas, and different parts of the detection component are respectively accommodated in different sub-areas, so as to reduce the interference of external heat sources and heat from external areas on the detection components in the sub-areas, and at the same time reduce the interference of the heat of the detection components in each sub-area on the detection components in other sub-areas, thereby further improving the accuracy of the thermal mass flow sensor.

[0019] In some embodiments, a break portion is provided on the thermal insulation structure, so that part of the thermal insulation area is connected to the external area through the break portion.

[0020] In the technical solution of this embodiment, a fracture portion is provided, and the thermal insulation structure is cut through the fracture portion, so that the thermal insulation area can be connected to the external area through the fracture portion, thereby reducing the difficulty of manufacturing the thermal insulation structure and the thermal insulation area.

[0021] In some embodiments, a ratio of the length of the fracture portion to the length of the thermal insulation structure is less than or equal to 50%.

[0022] The technical solution of this embodiment provides a length range of the fracture portion so that the thermal insulation structure can not only reduce the interference of external heat sources and heat from external areas on the thermal insulation area, but also reduce the manufacturing difficulty of the thermal insulation structure and the thermal insulation area.

[0023] In some embodiments, the width of the thermal insulation structure is greater than or equal to 0.1 mm, and the ratio of the width of the thermal insulation structure to the width of the housing is less than or equal to 20%.

[0024] The technical solution of this embodiment provides a wide range of insulation structures, so that the insulation structure can not only reduce the interference of external heat sources and heat in the external area on the detection components in the insulation area, but also reduce the negative impact on other structures in the outer shell and reduce the space requirement of the insulation structure.

[0025] In some embodiments, the detection assembly includes a tube and two boundary structures, one end of each of the two boundary structures is connected to the tube, and the other end of each of the two boundary structures is connected to the housing;

[0026] The detection component also includes two thermistors connected to the pipe fittings. The two thermistors are located between the two boundary structures. The two thermistors and the adjacent pipe fittings are covered with a heat preservation structure, and the heat preservation structure is connected to the shell.

[0027] The technical solution of this embodiment provides some specific structures of the detection components. The thermistor exchanges heat with the fluid flowing through and heats the fluid flowing through. The heat exchange will also cause the heating power of the thermistor to change. The voltage on the two thermistors is measured and converted to convert the fluid flow into an electrical signal, so that the thermal mass flow sensor can have higher accuracy.

[0028] In some embodiments, the two thermistors and at least a portion of the thermal insulation structure are located in the thermal insulation region.

[0029] In the technical solution of this embodiment, since the thermistor is a structure in the detection component that is more easily disturbed by the external heat source and the heat in the external area, and the thermistor has a greater impact on the accuracy of the thermal mass flow sensor after being disturbed; therefore, locating the thermistor in the thermal insulation area can reduce the negative impact of the external heat source and the heat in the external area on the accuracy of the thermal mass flow sensor.

[0030] In some embodiments, two boundary structures are located in the thermally insulating region.

[0031] In the technical solution of this embodiment, the boundary structure is located in the thermal insulation area. Since the heat in the pipe is easily conducted to the outer shell through the boundary structure, the heat generated by the boundary structure can be distributed more quickly and evenly in the thermal insulation area, so as to reduce the temperature gradient in the thermal insulation area, thereby reducing the negative impact of the temperature gradient on the accuracy of the thermal mass flow sensor.

[0032] In some embodiments, the thermal insulation region includes three sub-regions, the two thermistors and at least a portion of the thermal insulation structure are located in any one of the three sub-regions, and the two boundary structures are located in the other two of the three sub-regions, respectively.

[0033] In the technical solution of this embodiment, the two thermistors and at least part of the insulation structure and the two boundary structures are located in different sub-areas, respectively, so as to reduce the interference of the external heat source and the heat of the external area on the thermistors, and at the same time, the interference of the two boundary structures on the thermistors can be reduced, thereby further improving the accuracy of the thermal mass flow sensor.

[0034] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 A three-dimensional schematic diagram of a thermal mass flow sensor provided in some embodiments of the present application.

[0037] Figure 2 Schematic diagram of the internal structure of the thermal mass flow sensor provided in some other embodiments of the present application Figure 1 .

[0038] Figure 3 Schematic diagram 2 of the internal structure of a thermal mass flow sensor provided for other embodiments of the present application.

[0039] Figure 4 Schematic diagram 3 of the internal structure of the thermal mass flow sensor provided for other embodiments of the present application.

[0040] Figure 5Figure 4 is a schematic diagram of the internal structure of a thermal mass flow sensor provided in some other embodiments of the present application.

[0041] Figure 6 Schematic diagram 5 of the internal structure of the thermal mass flow sensor provided for other embodiments of the present application.

[0042] The meanings of the marks in the figure are:

[0043] 100. Thermal mass flow sensor;

[0044] 10. Shell; 11. Insulation area; 111. Sub-area; 12. External area;

[0045] 20. thermal insulation structure; 21. partition groove; 22. fracture part;

[0046] 30. Detection assembly; 31. Pipe fittings; 32. Boundary structure; 33. Thermistor; 34. Insulation structure. DETAILED DESCRIPTION

[0047] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0049] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0050] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0051] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0052] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0053] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0054] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0055] In application scenarios that require high-precision flow measurement and control, thermal mass flow meters, thermal mass flow controllers and other devices are often used to measure and control flow. These devices mainly use thermal mass flow sensors to achieve flow detection functions.

[0056] In current thermal mass flow sensors, two thermistor windings are usually wound at different positions of the capillary. When there is no fluid flow in the capillary, the heating power of the two thermistor windings remains balanced. When there is fluid flowing in the capillary, the fluid flow will successively exchange heat with the two thermistor windings, and will cause the heating power of the two thermistor windings to change, and this change increases with the increase of the fluid mass flow rate. By measuring the voltage on the two thermistor windings and converting it, the fluid flow rate can be converted into an electrical signal, thereby realizing the measurement of the mass flow rate.

[0057] During the heat transfer process of the thermal mass flow sensor, part of the heat generated by the thermistor winding is transferred to the capillary wall through heat conduction and exchanges heat with the fluid in the capillary; part of the heat is conducted to the shell of the thermal mass flow sensor through the insulation material outside the thermistor winding. In addition, when the fluid enters and leaves the heating area of ​​the thermistor winding, it conducts heat with the shell through the high thermal conductivity material to form a fixed temperature boundary. Therefore, the temperature stability of the shell is crucial to the performance of the thermal mass flow sensor.

[0058] In actual use, both internal and external heat sources may cause uneven shell temperature. For internal heat sources, the heat leakage of the insulation material will cause the temperature of the shell near the insulation material to be higher and form a temperature gradient on the shell; when the fluid flows through the temperature boundary, the temperature of the shell near the temperature boundary is also higher and forms a temperature gradient on the shell. For external heat sources, the heat generated by the control unit of the thermal mass flow sensor (such as printed circuit boards and other structures), the throttling effect of the fluid before and after flowing into the capillary, and the heat generated by other structures may all be conducted to the shell and form a temperature gradient on the shell.

[0059] Based on the above considerations, in order to reduce the temperature gradient near the thermistor and improve the measurement accuracy of the thermal mass flow sensor, the present application provides a thermal mass flow sensor, wherein a thermal insulation structure is arranged on the outer shell, a thermal insulation area and an external area are formed on the outer shell through the thermal insulation structure, and at least a part of the detection component is accommodated in the thermal insulation area.

[0060] In such a thermal mass flow sensor, the thermal insulation structure can reduce the impact of heat from the external area on the temperature in the thermal insulation area, so as to reduce the temperature gradient generated by the external heat source in the thermal insulation area, thereby reducing the interference of the external heat source on the detection component in the thermal insulation area, and further reducing the negative impact of the external heat source on the accuracy of the thermal mass flow sensor; the heat generated by the detection component inside the thermal insulation area can be quickly and evenly distributed in the thermal insulation area to reduce the temperature gradient inside the thermal insulation area, thereby reducing the interference of the internal heat source on the detection component in the thermal insulation area, and further reducing the negative impact of the heat source on the accuracy of the thermal mass flow sensor.

[0061] In order to illustrate the technical solution of the present application, a description is given below with reference to specific drawings and embodiments.

[0062] refer to Figures 1 to 3The embodiment of the present application provides a thermal mass flow sensor 100, comprising: a housing 10, a detection component 30 and a thermal insulation structure 20; wherein the detection component 30 is arranged in the housing 10; the thermal insulation structure 20 is arranged on the housing 10, and the thermal insulation structure 20 is used to enclose a thermal insulation area 11 and an external area 12 located outside the thermal insulation area 11 on the housing 10, and at least a portion of the thermal insulation area 11 is separated from the external area 12; at least a portion of the detection component 30 is accommodated in the thermal insulation area 11.

[0063] The shell 10 refers to a structure in the thermal mass flow sensor 100 that is mainly used to provide a fixed foundation for the detection component 30 and the insulation structure 20 and to protect the insulation structure 20 and the detection component 30; the shape of the shell 10 can be square, round or other shapes; a cavity is provided inside the shell 10 to accommodate the detection component 30 and the insulation structure 20, and the shape of the cavity can be square, round or other shapes; the material of the shell 10 can include metal, plastic or other materials.

[0064] The detection component 30 refers to a structure in the thermal mass flow sensor 100 that is mainly used to detect flow. The detection component 30 may include a thermistor 33, a capillary, and other structures. The detection component 30 is disposed in the housing 10. For example, the detection component 30 may be fixedly connected to the housing 10 by gluing, welding, or the like, or may be detachably connected to the housing 10 by snap-on, screw-on, or the like.

[0065] The detection component 30 is disposed in the housing 10 to protect the detection component 30 . The housing 10 can also serve as a temperature boundary of the detection component 30 to reduce possible interference of the external environment (such as external temperature) on the detection component 30 .

[0066] The detection component 30 can be arranged on any side wall of the shell 10. For example, the detection component 30 is arranged on the side wall of the shell 10 with the largest area to reduce the negative impact of space on the arrangement of the detection component 30 and facilitate the arrangement of the detection component 30. The detection component 30 can be in contact with only one side wall of the shell 10, or with two opposite side walls of the shell 10, or with multiple side walls of the shell 10.

[0067] It can be understood that, since the detection component 30 is disposed on the side wall of the housing 10 , the heat generated by the detection component 30 can be conducted to the side wall of the housing 10 and dissipated to the space outside the housing 10 through the side wall of the housing 10 .

[0068] The thermal insulation structure 20 refers to a structure in the thermal mass flow sensor 100 that is mainly used to block heat. The thermal insulation structure 20 can enclose a thermal insulation area 11 and an external area 12 on the outer shell 10 to reduce the impact of the heat in the external area 12 on the thermal insulation area 11; the thermal insulation structure 20 can include a groove structure opened on the outer shell 10, and can also include a plate structure that penetrates the outer shell 10. The thermal insulation structure 20 can also include other structures.

[0069] According to the specific structure of the heat insulation structure 20, the heat insulation area 11 and the external area 12 can be planar areas formed on the side wall of the outer shell 10, or the heat insulation area 11 and the external area 12 can be spatial areas formed inside the outer shell 10; for example, since the heat of various parts in the thermal mass flow sensor 100 is mostly conducted through the outer shell 10, and the thermal conductivity of the air is relatively poor, the heat insulation area 11 and the external area 12 are both planar areas formed on the outer shell 10.

[0070] In the case where the heat insulating region 11 is a planar region formed on the side wall of the housing 10 , the heat insulating region 11 may be a square region, a circular region, or a region of other shapes.

[0071] Under the action of the heat insulation structure 20, at least part of the heat insulation area 11 is separated from the external area 12, that is, the heat insulation area 11 can be completely separated from the external area 12, or the heat insulation area 11 can be partially connected to the external area. When the heat insulation area 11 is completely separated from the external area 12, the heat of the external area 12 is not easily transferred to the heat insulation area 11, and the heat of the external area 12 has little effect on the heat insulation area 11, and the heat insulation effect of the heat insulation structure 20 is better; when part of the heat insulation area 11 is connected to the external area, the position of the heat insulation area 11 close to the heat insulation structure 20 or surrounded by the heat insulation structure 20 is not easily affected by the heat of the external area 12.

[0072] At least part of the detection assembly 30 is accommodated in the heat insulation area 11, that is, the detection assembly 30 can be completely accommodated in the heat insulation area 11 (refer to Figure 2 ), or may be only partially contained in the heat-insulating region 11 (see Figure 3 ); When the detection component 30 is only partially accommodated in the insulation area 11, the structure in the detection component 30 that is susceptible to temperature interference can be located in the insulation area 11.

[0073] The detection component 30 can be accommodated in the thermal insulation area 11, that is, along the direction perpendicular to the side wall where the detection component 30 is located, the projection of the detection component 30 can fall in the thermal insulation area 11; when the detection component 30 is completely accommodated in the thermal insulation area 11, the projection of the detection component 30 along the direction perpendicular to the side wall where it is located completely falls into the thermal insulation area 11; when the detection component 30 is only partially accommodated in the thermal insulation area 11, the partial projection of the detection component 30 along the direction perpendicular to the side wall where it is located falls into the thermal insulation area 11.

[0074] The thermal insulation structure 20 can be arranged on a certain side wall of the outer shell 10, and the thermal insulation structure 20 can also be arranged on two or more side walls of the outer shell 10 to enclose thermal insulation areas 11 on different side walls of the outer shell 10; it can be understood that the number of thermal insulation structures 20 can be determined according to the number of side walls on which the detection component 30 contacts the outer shell 10. For example, when the detection component 30 contacts two opposite side walls of the outer shell 10, the thermal insulation structure 20 is respectively arranged on the two side walls, and thermal insulation areas 11 are respectively formed on the two side walls to accommodate the detection component 30.

[0075] When the thermal mass flow sensor 100 is in use, the heat generated by other structures outside the detection component 30 or other structures outside the thermal mass flow sensor 100 can be conducted to the external area 12, but under the action of the thermal insulation structure 20, the heat of the external area 12 is not easily conducted to the thermal insulation area 11, so that the thermal insulation area 11 is not easily affected by other structures outside the detection component 30 to form a temperature gradient, so that the thermal insulation area 11 is not easily disturbed by other structures outside the detection component 30; at the same time, the heat generated by various parts of the detection component 30 can be conducted inside the thermal insulation area 11 and distributed more evenly in the thermal insulation area 11, so as to reduce the temperature gradient in the thermal insulation area 11, thereby reducing the interference of the detection component 30's own heat on its accuracy.

[0076] In this embodiment, a thermal insulation area 11 is enclosed on the outer shell 10 by the thermal insulation structure 20, and part of the detection component 30 is accommodated in the thermal insulation area 11 to reduce the interference of external heat sources on the part of the detection component 30 located in the thermal insulation area 11, thereby reducing the negative impact of the external heat source on the accuracy of the thermal mass flow sensor 100; at the same time, the heat generated by the part of the detection component 30 located in the thermal insulation area 11 can also be more evenly distributed in the thermal insulation area 11 to reduce the temperature gradient in the thermal insulation area 11, thereby further reducing the negative impact on the accuracy of the thermal mass flow sensor 100.

[0077] refer to Figures 1 to 3 In some embodiments, the thermal insulation structure 20 includes a partition groove 21 opened in the outer shell 10 .

[0078] The partition groove 21 refers to a groove structure opened on the shell 10. The partition groove 21 can be opened on a side wall of the shell 10, or on two or more side walls of the shell 10. The position of the partition groove 21 can be determined according to the number of side walls contacted by the detection component 30 and the shell 10 and the position of the detection component 30 relative to the shell 10; the partition groove 21 can penetrate the corresponding side wall of the shell 10 to separate the heat insulation area 11 from the external area 12; no filling material may be set in the partition groove 21. At this time, the heat insulation structure 20 blocks the heat of the external area 12 from being transferred to the heat insulation area 11 through the air in the partition groove 21, and the partition groove 21 can also be filled with heat insulation material; along the thickness direction of the side wall where the partition groove 21 is located, the cross-sectional shape of the partition groove 21 can be square, trapezoidal, semicircular or other shapes;

[0079] It can be understood that when the partition groove 21 is not filled with material but only with air, the insulation area 11 and the external area 12 can be partially separated and partially connected to reduce the difficulty of processing and laying out the insulation area 11; when the partition groove 21 is not filled with material but only with air, the insulation area 11 can also be completely separated from the external area 12. At this time, the side wall of the part of the outer shell 10 corresponding to the insulation area 11 can be connected to the inner wall of the part of the outer shell 10 corresponding to the external area 12 through other structural parts.

[0080] The present embodiment provides some specific structures of the heat insulation structure 20, which separates the heat insulation area 11 and the external area 12 on the outer shell 10 through the partition groove 21, so that the partition groove 21 can separate the heat insulation area 11 and the external area 12 through air, thereby reducing the interference of the heat of the external area 12 on the detection component 30 in the heat insulation area 11, thereby improving the accuracy of the thermal mass flow sensor 100.

[0081] In some embodiments, the thermal insulation structure 20 further includes a thermal insulation material filled in the partition groove 21 .

[0082] Thermal insulation materials refer to materials that can hinder heat transfer. Thermal insulation materials may include porous materials (such as glass fiber, asbestos, silicate, etc.), vacuum materials (such as vacuum insulation panels, etc.), etc. Thermal insulation materials may also include other materials that can hinder heat transfer.

[0083] Because the partition groove 21 passes through the side wall of the outer shell 10, filling the partition groove 21 with insulation material can also reduce the situation where dust and other impurities in the environment outside the outer shell 10 enter the inner part of the outer shell 10 through the partition groove 21, that is, filling the partition groove 21 with insulation material can also protect the detection component 30 and other structures in the outer shell 10.

[0084] The present embodiment further provides some specific structures of the thermal insulation structure 20, in which thermal insulation material is filled in the partition groove 21 to further separate the external area 12 and the thermal insulation area 11 through the thermal insulation material, thereby reducing the interference of the heat of the external area 12 with the detection component 30 in the thermal insulation area 11; at the same time, the thermal insulation area 11 can also be connected to the external area 12 through the thermal insulation material, so that the partition groove 21 encloses the thermal insulation area 11 into a closed area, thereby better reducing the interference of the heat of the external area 12 with the detection component 30 in the thermal insulation area 11.

[0085] In some embodiments, the thermal conductivity of the material of the housing 10 is greater than or equal to 10 W / (m·k) (watt / meter·degree), and the thermal conductivity of the insulation material is less than or equal to 5 W / (m·k).

[0086] For example, the thermal conductivity of the shell 10 can be 10W / (m·k), 15W / (m·k), 20W / (m·k), 50W / (m·k), 100W / (m·k), 200W / (m·k) or other values; accordingly, the material of the shell 10 can include metal with a thermal conductivity greater than or equal to 10W / (m·k) or other materials with good thermal conductivity.

[0087] For example, the thermal conductivity of the thermal insulation material can be 5 W / (m·k), 1 W / (m·k), 0.1 W / (m·k), 0.01 W / (m·k) or other values. Accordingly, the material of the thermal insulation material can include glass fiber, asbestos or other materials with poor thermal conductivity whose thermal conductivity is less than or equal to 5 W / (m·k).

[0088] In this embodiment, the thermal conductivity of the material of the outer shell 10 is made larger, so that the material of the thermal insulation area 11 can also have a larger thermal conductivity, so that the temperature in the thermal insulation area 11 can be conducted faster and evenly distributed, thereby reducing the temperature gradient in the thermal insulation area 11; at the same time, the thermal conductivity of the thermal insulation material is made smaller to reduce the interference of external heat sources and heat in the external area 12 on the detection component 30 in the thermal insulation area 11.

[0089] refer to Figure 2 In some embodiments, the thermal insulation structure 20 is used to separate the thermal insulation area 11 from the external area 12 , and the detection component 30 is accommodated in the thermal insulation area 11 .

[0090] The thermal insulation structure 20 can completely separate the thermal insulation area 11 from the external area 12 to better prevent the heat in the external area 12 from being transferred to the thermal insulation area 11, thereby reducing the temperature gradient formed by the heat of the external area 12 in each thermal insulation area 11 and reducing the interference of the heat of the external area 12 on the detection component 30 in the thermal insulation area 11.

[0091] For example, when the heat insulation structure 20 is a partition groove 21 , the partition groove 21 may be a ring-shaped closed structure with connected ends, so as to completely separate the heat insulation area 11 from the external area 12 .

[0092] The detection assembly 30 is accommodated in the heat-insulating area 11 , that is, the detection assembly 30 is completely accommodated in the heat-insulating area 11 , so that the detection assembly 30 can be better protected by the heat-insulating structure 20 , thereby reducing the interference of the heat of the external area 12 on the detection assembly 30 .

[0093] In this embodiment, the thermal insulation area 11 is completely separated from the external area 12 by the thermal insulation structure 20, and the detection component 30 is completely accommodated in the thermal insulation area 11 to reduce the interference of external heat sources and heat in the external area 12 on the detection component 30, thereby improving the accuracy of the thermal mass flow sensor 100.

[0094] refer to Figure 4 , Figure 5 In some embodiments, a fracture portion 22 is provided on the thermal insulation structure 20 so that a portion of the thermal insulation area 11 is connected to the external area 12 through the fracture portion 22 .

[0095] The fracture portion 22 refers to a partial structure in the thermal insulation structure 20 that does not separate the thermal insulation area 11 from the external area 12; the fracture portion 22 may be in a square, trapezoidal or other shapes; the fracture portion 22 may be a part of the side wall of the outer shell 10, in which case the two ends of the fracture portion 22 are respectively connected to the thermal insulation area 11 and the external area 12; the fracture portion 22 may also be an independent structure and connected to the thermal insulation area 11 and the external area 12.

[0096] The number of the fracture portions 22 may be one or two or more; when the number of the fracture portions 22 is two or more, the plurality of fracture portions 22 may be evenly distributed around the thermal insulation region 11 or unevenly distributed around the thermal insulation region 11.

[0097] When the insulation structure 20 is a partition groove 21, the side wall of the shell 10 corresponding to the insulation area 11 can be connected to the side wall of the shell 10 corresponding to the external area 12 through the fracture portion 22, thereby reducing the difficulty of arranging and manufacturing the insulation area 11 and the insulation structure 20.

[0098] It can be understood that the heat in the external area 12 can be conducted to the heat-insulating area 11 through the broken portion 22 , so the position of the broken portion 22 can avoid the structure in the detection component 30 that is greatly affected by the heat.

[0099] In this embodiment, a fracture portion 22 is provided and the thermal insulation structure 20 is cut through the fracture portion 22 so that the thermal insulation area 11 can be connected to the external area 12 through the fracture portion 22, thereby reducing the manufacturing difficulty of the thermal insulation structure 20 and the thermal insulation area 11.

[0100] refer to Figure 4 , Figure 5 In some embodiments, the ratio of the length of the fracture portion 22 to the length of the thermal insulation structure 20 is less than or equal to 50%; for example, the ratio of the length of the fracture portion 22 to the length of the thermal insulation structure 20 can be 50%, 45%, 40%, 35%, 30%, 25%, 20% or other values.

[0101] The length of the fracture portion 22 refers to the size of the fracture portion 22 in the extension direction of the thermal insulation structure 20. For example, when the thermal insulation structure 20 is an annular partition groove 21, the length of the fracture portion 22 is the size of the fracture portion 22 in the circumferential direction of the annular partition groove 21. Figure 4 , the length of the fracture portion 22 is the length shown by L in the figure; when the number of the fracture portions 22 is two or more, the length of the fracture portion 22 is the sum of the lengths of the plurality of fracture portions 22 .

[0102] The length of the thermal insulation structure 20 refers to the size of the thermal insulation structure 20 in its extension direction. For example, when the thermal insulation structure 20 is an annular partition groove 21, the length of the thermal insulation structure 20 is the size of the thermal insulation structure 20 in its circumferential direction.

[0103] The length of the fracture portion 22 is negatively correlated with the thermal insulation capacity of the thermal insulation structure 20, that is, the larger the length of the fracture portion 22, the worse the thermal insulation capacity of the thermal insulation structure 20, the easier it is for the heat of the external area 12 to produce a temperature gradient in the thermal insulation area 11, and the greater the impact of the heat of the external area 12 on the thermal insulation area 11.

[0104] Accordingly, the length of the fracture portion 22 should not be too long. In this embodiment, the ratio of the length of the fracture portion 22 to the length of the thermal insulation structure 20 is less than or equal to 50% to limit the length of the fracture portion 22. This can not only enable the thermal insulation structure 20 to reduce the interference of external heat sources and heat from the external area 12 on the thermal insulation area 11, but also reduce the manufacturing difficulty of the thermal insulation structure 20 and the thermal insulation area 11.

[0105] refer to Figure 4 In some embodiments, the width of the thermal insulation structure 20 is greater than or equal to 0.1 mm, and the ratio of the width of the thermal insulation structure 20 to the width of the housing 10 is less than or equal to 20%.

[0106] For example, the width of the thermal insulation structure 20 may be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or other values.

[0107] For example, the ratio of the width of the thermal insulation structure 20 to the width of the housing 10 may be 20%, 18%, 15%, 12%, 10% or other values.

[0108] The width of the thermal insulation structure 20 refers to the dimension of the thermal insulation structure 20 in a direction perpendicular to its extension. For example, when the thermal insulation structure 20 is an annular partition groove 21, the width of the thermal insulation structure 20 is the dimension of the thermal insulation structure 20 in its radial direction. Figure 4 The width of the thermal insulation structure 20 is the dimension shown as W in the figure.

[0109] The width of the shell 10 refers to the dimension of the shell 10 in the extension direction perpendicular to the thermal insulation structure 20 . For example, when the thermal insulation structure 20 is an annular partition groove 21 , the width of the shell 10 is the dimension of the shell 10 in the radial direction of the thermal insulation structure 20 .

[0110] Because the width of the insulation structure 20 is positively correlated with the insulation capacity of the insulation structure 20, that is, the larger the width of the insulation structure 20, the stronger the insulation capacity of the insulation structure 20, the less likely the heat of the external area 12 is to produce a temperature gradient in the insulation area 11, and the smaller the influence of the heat of the external area 12 on the insulation area 11.

[0111] The width of the heat insulation structure 20 will also affect the internal space of the housing 10 , that is, the larger the width of the heat insulation structure 20 , the smaller the remaining space in the housing 10 , and the smaller the layout space of other structures in the thermal mass flow sensor 100 .

[0112] Accordingly, this embodiment provides a width range of the thermal insulation structure 20, so that the thermal insulation structure 20 can not only reduce the interference of external heat sources and heat from the external area 12 on the detection component 30 in the thermal insulation area 11, but also reduce the negative impact on other structures in the outer shell 10 and reduce the space requirement of the thermal insulation structure 20.

[0113] refer to Figure 6 In some embodiments, the thermal insulation region 11 includes at least two sub-regions 111 , and the sub-regions 111 are used to accommodate part of the detection component 30 .

[0114] The sub-region 111 refers to a part of the insulation region 11. According to the shape of the insulation region 11, the sub-region 111 may be a planar region formed on the side wall of the outer shell 10, or the sub-region 111 may be a spatial region formed inside the outer shell 10. For example, since the heat of various parts of the thermal mass flow sensor 100 is mostly conducted through the outer shell 10, and the heat conduction capacity of the air is relatively poor, the sub-region 111 is a planar region formed on the outer shell 10.

[0115] In the case where the sub-region 111 is a planar region formed on the side wall of the housing 10 , the sub-region 111 may be a square region, a circular region, or a region of other shapes.

[0116] The sub-region 111 is surrounded by the heat insulation structure 20 . Under the action of the heat insulation structure 20 , the sub-region 111 can be completely separated from the external region 12 . The sub-region 111 can also be partially separated from the external region 12 and partially connected.

[0117] There are at least two sub-regions 111, that is, the number of sub-regions 111 can be two, or three or more. The multiple sub-regions 111 can be arranged in sequence along one direction or in different directions. The area of ​​each sub-region 111 can be the same or different.

[0118] Different parts of the detection component 30 can be respectively accommodated in different sub-areas 111. On this basis, the detection component 30 can be completely accommodated in the thermal insulation area 11 and respectively accommodated in each sub-area 111, or only partially accommodated in the thermal insulation area 11 and partially located outside each sub-area 111. When the detection component 30 is only partially accommodated in the thermal insulation area 11, the structure in the detection component 30 that is susceptible to temperature interference can be located in the thermal insulation area 11.

[0119] The detection component 30 can be accommodated in the sub-area 111, that is, along the direction perpendicular to the side wall where the detection component 30 is located, the projection of the detection component 30 can fall in the sub-area 111; when different parts of the detection component 30 are completely accommodated in each sub-area 111, the projections of different parts of the detection component 30 along the direction perpendicular to the side wall where they are located fall into each sub-area 111 respectively; when part of the detection component 30 is located outside each sub-area 111, the partial projection of the detection component 30 along the direction perpendicular to the side wall where it is located falls outside each sub-area 111.

[0120] In this embodiment, the heat-insulating area 11 includes at least two sub-areas 111, and different parts of the detection component 30 are respectively accommodated in different sub-areas 111, so as to reduce the interference of the external heat source and the heat of the external area 12 on the detection component 30 in the sub-area 111, and at the same time, it can also reduce the interference of the heat of the detection component 30 in each sub-area 111 on the detection component 30 in other sub-areas 111, thereby further improving the accuracy of the thermal mass flow sensor 100.

[0121] refer to Figures 1 to 6In some embodiments, the detection component 30 includes a pipe 31 and two boundary structures 32, one end of the two boundary structures 32 are connected to the pipe 31, and the other ends of the two boundary structures 32 are connected to the housing 10; the detection component 30 also includes two thermistors 33 connected to the pipe 31, the two thermistors 33 are located between the two boundary structures 32, and the two thermistors 33 and the adjacent pipe 31 are covered with an insulation structure 34, and the insulation structure 34 is connected to the housing 10.

[0122] The pipe fitting 31 refers to a structure in the detection component 30 that is mainly used for fluid to flow through; the pipe fitting 31 can be a capillary tube, or a pipe fitting 31 of other structures; along the radial direction of the pipe fitting 31, the cross-sectional shape of the pipe fitting 31 can be circular, square or other shapes; the material of the pipe fitting 31 can include glass, or metal, plastic or other materials.

[0123] The thermistor 33 refers to a structure in the detection component 30 that is mainly used to heat the fluid flowing through it. After the fluid enters the pipe 31, the fluid can flow through two thermistors 33 in sequence and exchange heat with the corresponding thermistors 33. The heat exchange will cause the heating power of the thermistor 33 to change. By measuring the voltage on the two thermistors 33 and converting it, the fluid flow rate can be converted into an electrical signal, thereby realizing the measurement of the mass flow rate.

[0124] The boundary structure 32 refers to a structure in the detection component 30 that is mainly used as a temperature boundary. The two thermistors 33 are located between the two boundary structures 32. That is, after the fluid enters the pipe 31, the fluid will flow through one boundary structure 32, and then flow through the two thermistors 33 in sequence, and then flow through the other boundary structure 32 before flowing out of the pipe 31.

[0125] When the fluid flows through the boundary structure 32, the heat carried by the fluid will be conducted to the outer shell 10 through the boundary structure 32, and dissipated to the space outside the outer shell 10 through the outer shell 10. Accordingly, the material of the boundary structure 32 may include materials with good thermal conductivity, such as metal, graphite, silicone, etc.; one end of the boundary structure 32 is connected to the pipe 31 and the other end is connected to the outer shell 10, and the heat carried by the fluid can be conducted to the outer shell 10 through the boundary structure 32. At the same time, the boundary structure 32 can also play a role in supporting and fixing the pipe 31; the shape of the boundary structure 32 can be cylindrical, prismatic or other shapes.

[0126] The insulation structure 34 refers to a structure in the detection component 30 that is wrapped around the thermistor 33 and part of the pipe 31 adjacent to the thermistor 33. The insulation structure 34 is used to reduce the heat exchange between the thermistor 33 and other structures so as to better maintain the temperature stability of the thermistor 33; accordingly, the material of the insulation structure 34 may include ceramic material, glass fiber or other materials with good thermal insulation performance.

[0127] The heat-insulating structure 34 can also be used to protect the thermistor 33 .

[0128] This embodiment provides some specific structures of the detection assembly 30 so that the thermal mass flow sensor 100 can measure the flow rate of the fluid through the two thermistors 33 and the thermal mass flow sensor 100 can have higher accuracy.

[0129] refer to Figure 3 In some embodiments, at least a portion of the two thermistors 33 and the thermal insulation structure 34 are located in the thermal insulation area 11 .

[0130] The thermistor 33 is located in the heat-insulating region 11 , that is, a projection of the thermistor 33 along a direction perpendicular to a side wall of the housing 10 where the thermistor 33 is located is located in the heat-insulating region 11 .

[0131] Since the thermistor 33 is the main structure for measuring flow in the thermal mass flow sensor 100, the temperature gradient on the housing 10 near the thermistor 33 is likely to interfere with the thermistor 33. Therefore, the thermistor 33 is located in the thermal insulation area 11 to reduce the temperature gradient generated in the thermal insulation area 11 by the heat of the external area 12, thereby reducing the negative impact of the heat of the external area 12 on the detection accuracy of the thermal mass flow sensor 100.

[0132] At least part of the heat-insulating structure 34 is located in the heat-insulating region 11 , that is, a projection of the heat-insulating structure 34 along a direction perpendicular to the side wall of the housing 10 where the heat-insulating structure 34 is located is located in the heat-insulating region 11 .

[0133] The thermal insulation structure 34 can be completely contained in the thermal insulation area 11, or only partially contained in the thermal insulation area 11; because the thermal insulation structure 34 covers the thermistor 33 and part of the pipe 31, at least the part of the thermal insulation structure 34 close to the thermistor 33 can be located in the thermal insulation area 11; and because the thermal insulation structure 34 is used to reduce the heat exchange between the thermistor 33 and other structures, that is, the thermal conductivity of the thermal insulation structure 34 is poor, at this time, even if part of the thermal insulation structure 34 is located outside the thermal insulation area 11, this part of the thermal insulation structure 34 is not easy to transfer heat to the thermistor 33.

[0134] As an example, the two thermistors 33 and the heat preservation structure 34 are both accommodated in the heat insulation area 11 .

[0135] In this embodiment, since the thermistor 33 is a structure in the detection component 30 that is more easily disturbed by the external heat source and the heat in the external area 12, and the thermistor 33 has a greater impact on the accuracy of the thermal mass flow sensor 100 after being disturbed; therefore, locating the thermistor 33 in the insulation area 11 can reduce the negative impact of the external heat source and the heat in the external area 12 on the accuracy of the thermal mass flow sensor 100.

[0136] refer to Figure 2 , Figure 4 , Figure 5 In some embodiments, two boundary structures 32 are located in the thermal insulation region 11 .

[0137] The boundary structure 32 is located in the heat insulation region 11 , that is, the projection of the boundary structure 32 along a direction perpendicular to the side wall of the housing 10 where the boundary structure 32 is located is located in the heat insulation region 11 .

[0138] Because the boundary structure 32 is connected to both the housing 10 and the pipe 31, and the boundary structure 32 can exchange heat with the fluid in the pipe 31, that is, the heat of the external area 12 can also be transferred to the pipe 31 through the boundary structure 32 and finally transferred to the fluid, the temperature gradient of the external area 12 can also interfere with the measurement accuracy of the thermal mass flow sensor 100.

[0139] Accordingly, the boundary structure 32 is located in the heat-insulating region 11 to reduce the negative impact of the heat of the external region 12 on the measurement accuracy of the thermal mass flow sensor 100 .

[0140] Because the heat in the pipe 31 is easily conducted to the outer shell 10 in the boundary structure 32, and because the outer shell 10 includes a material with strong thermal conductivity, locating the boundary structure 32 in the thermal insulation area 11 can make the heat generated by the boundary structure 32 more quickly and evenly distributed in the thermal insulation area 11, so as to reduce the temperature gradient in the thermal insulation area 11, thereby reducing the negative impact of the temperature gradient on the accuracy of the thermal mass flow sensor 100.

[0141] refer to Figure 6 In some embodiments, the thermal insulation region 11 includes three sub-regions 111 , the two thermistors 33 and at least a portion of the thermal insulation structure 34 are located in any one of the three, and the two boundary structures 32 are located in the other two of the three.

[0142] The sub-region 111 is a part of the heat-insulating region 11, and the structure in the sub-region 111 is not easily disturbed by the heat of the external region 12, and the heat of the external region 12 is not easy to form a temperature gradient in the sub-region 111; at the same time, because the heat-insulating region 11 is a region formed on the side wall of the outer shell 10, the sub-region 111 is also a region formed on the side wall of the outer shell 10; and because the outer shell 10 includes a material with strong thermal conductivity, the temperature in the sub-region 111 formed on the side wall of the outer shell 10 can also be more quickly and evenly distributed in the entire sub-region 111, so that the temperature gradient in the sub-region 111 can be smaller.

[0143] The thermistor 33 and the heat preservation structure 34 are located in a sub-region 111, and the two boundary structures 32 are located in two sub-regions 111 respectively, so that the thermistor 33 and the two boundary structures 32 are not easily disturbed by the heat of the external region 12, thereby reducing the temperature gradient in the sub-region 111; at the same time, the temperature inside the sub-region 111 can also be distributed relatively quickly and evenly in the entire sub-region 111, further reducing the temperature gradient in the sub-region 111; separating the two boundary structures 32 and the thermistor 33 from each other can also reduce the mutual interference among the three, further reducing the temperature gradient in the sub-region 111, and reducing the negative impact on the accuracy of the thermal mass flow sensor 100.

[0144] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A thermal mass flow sensor, characterized in that: include: A housing, wherein a detection component is disposed in the housing; a heat insulation structure, provided on the outer shell, the heat insulation structure being used to enclose a heat insulation area and an external area outside the heat insulation area on the outer shell, wherein at least a part of the heat insulation area is separated from the external area; At least a portion of the detection assembly is accommodated in the thermally insulating region.

2. The thermal mass flow sensor according to claim 1, characterized in that: The heat insulation structure includes a partition groove opened in the shell.

3. The thermal mass flow sensor according to claim 2, characterized in that: The heat insulation structure also includes a heat insulation material filled in the partition groove.

4. The thermal mass flow sensor according to claim 3, characterized in that: The thermal conductivity of the material of the shell is greater than or equal to 10 W / (m·k), and the thermal conductivity of the thermal insulation material is less than or equal to 5 W / (m·k).

5. The thermal mass flow sensor according to any one of claims 1 to 4, characterized in that: The heat insulation structure is used to separate the heat insulation area from the external area, and the detection component is accommodated in the heat insulation area.

6. The thermal mass flow sensor according to any one of claims 1 to 4, characterized in that: The thermal insulation area includes at least two sub-areas, and the sub-areas are used to accommodate parts of the detection component.

7. The thermal mass flow sensor according to any one of claims 1 to 4, characterized in that: The thermal insulation structure is provided with a fracture portion, so that part of the thermal insulation area is connected to the external area through the fracture portion.

8. The thermal mass flow sensor according to claim 7, characterized in that: The ratio of the length of the fracture portion to the length of the thermal insulation structure is less than or equal to 50%.

9. The thermal mass flow sensor according to claim 1, characterized in that: The width of the heat insulation structure is greater than or equal to 0.1 mm, and the ratio of the width of the heat insulation structure to the width of the shell is less than or equal to 20%.

10. The thermal mass flow sensor according to claim 1, characterized in that: The detection assembly includes a pipe and two boundary structures, one end of each of the two boundary structures is connected to the pipe, and the other ends of each of the two boundary structures are connected to the housing; The detection component also includes two thermistors connected to the pipe, the two thermistors are located between the two boundary structures, the two thermistors and the adjacent pipe parts are covered with a thermal insulation structure, and the thermal insulation structure is connected to the shell.

11. The thermal mass flow sensor according to claim 10, characterized in that: The two thermistors and at least a portion of the thermal insulation structure are located in the thermal insulation area.

12. The thermal mass flow sensor according to claim 10 or 11, characterized in that: The two boundary structures are located in the thermal insulation region.

13. The thermal mass flow sensor according to claim 12, characterized in that: The heat-insulating region includes three sub-regions, the two thermistors and at least a portion of the heat-insulating structure are located in any one of the three sub-regions, and the two boundary structures are located in the other two of the three sub-regions.

Images