Gas sensor

Abstract

This gas sensor comprises: a substrate; a detection element that is supported by the substrate and has a detection unit; an inner wall that is supported by the substrate and surrounds the detection unit; an outer wall that is supported by the substrate and surrounds the inner wall; and a lid part that is supported by the inner wall and the outer wall, closes a detection chamber that is a space inside the inner wall in which the detection unit is provided, and closes a flow path that is a space between the inner wall and the outer wall. The outer wall has a first outer hole penetrating in a first direction so as to communicate the outer side of the outer wall and the flow path, and a second outer hole provided on the opposite side of the first outer hole with respect to the detection chamber in the first direction and penetrating in the first direction so as to communicate the outer side of the outer wall and the flow path. The inner wall has an inner hole penetrating in a second direction so as to communicate the flow path and the detection chamber, the second direction intersecting the first direction.

Description

Gas Sensor

[0001] The present disclosure relates to a gas sensor for detecting a gas concentration.

[0002] A gas sensor detects a gas concentration by utilizing, for example, a difference in thermal conductivity depending on the gas concentration. For example, a gas sensor detects the concentration of a gas based on a change in resistance of a detection element caused by a difference in the amount of heat dissipated from the detection element heated by the gas into the atmosphere. Examples of gas sensors are disclosed in Patent Documents 1 and 2.

[0003] Chinese Utility Model No. 212513174 Patent Publication No. 2015-004609

[0004] In the gas sensor described above, fluctuations in the flow rate and direction of gas taken into the gas sensor from outside the gas sensor, where the detection element is provided, may deteriorate the detection accuracy.

[0005] In the gas sensor described in Patent Document 1, gas enters the interior of the gas sensor from the outside through an intake hole provided on the side. Here, in the gas sensor described in Patent Document 1, the detection element is provided on an extension of the intake hole. Therefore, gas concentration detection by the detection element is easily affected by the gas that has entered the interior through the intake hole, which may result in a deterioration in detection accuracy.

[0006] In the gas sensor described in Patent Document 2, an expansion chamber is provided between an intake hole and a measurement chamber in which a detection element is provided. Gas entering through the intake hole flows into the measurement chamber via the expansion chamber. The expansion chamber expands the gas communication path, which can slow down the speed of gas entering the interior through the intake hole. This can reduce fluctuations in the gas flow rate.

[0007] However, in the gas sensor described in Patent Document 2, as in the gas sensor described in Patent Document 1, the detection element is provided on an extension line from the intake hole through the expansion chamber. Therefore, the detection of gas concentration by the detection element is easily affected by gas that has entered the gas sensor, which may deteriorate the detection accuracy. Furthermore, the provision of an expansion chamber with roughly the same shape and size as the measurement chamber results in an increase in the size of the gas sensor.

[0008] Therefore, an object of the present disclosure is to solve the above-mentioned problems by providing a gas sensor that can suppress an increase in size and a decrease in the accuracy of detecting gas concentrations.

[0009] a detection element supported by the substrate and having a detection portion; an inner wall supported by the substrate and surrounding the detection portion when viewed in an orthogonal direction orthogonal to a support surface on which the substrate supports the detection element; an outer wall supported by the substrate and surrounding the inner wall when viewed in the orthogonal direction; and a lid supported by the inner wall and the outer wall, closing a detection chamber in which the detection portion is provided, which is a space inside the inner wall when viewed in the orthogonal direction, and closing a flow path which is a space between the inner wall and the outer wall when viewed in the orthogonal direction; wherein the outer wall has at least one first outer hole penetrating in a first direction to communicate an outside of the outer wall with the flow path, and at least one second outer hole provided on an opposite side of the first outer hole with respect to the detection chamber in the first direction and penetrating in the first direction to communicate an outside of the outer wall with the flow path, The inner wall has at least one inner hole penetrating in a second direction intersecting the first direction so as to connect the flow path and the detection chamber.

[0010] According to the present disclosure, it is possible to provide a gas sensor that can suppress a decrease in the accuracy of detecting gas concentration while suppressing an increase in size.

[0011] 1 is a schematic perspective view of a gas sensor according to a first embodiment of the present disclosure; a schematic perspective view of a portion of the gas sensor according to the first embodiment of the present disclosure, from which a lid portion has been removed; a schematic perspective view of a gas sensor according to a second embodiment of the present disclosure; a schematic plan view of a portion of the gas sensor according to a third embodiment of the present disclosure, from which a lid portion has been removed; a schematic plan view of a portion of the gas sensor according to a fourth embodiment of the present disclosure, from which a lid portion has been removed; a schematic plan view of a portion of the gas sensor according to a fifth embodiment of the present disclosure, from which a lid portion has been removed; a schematic plan view of a portion of the gas sensor according to a sixth embodiment of the present disclosure, from which a lid portion has been removed; a schematic plan view of a portion of the gas sensor according to a seventh embodiment of the present disclosure, from which a lid portion has been removed; a schematic plan view of a portion of the gas sensor according to an eighth embodiment of the present disclosure, from which a lid portion has been removed; a schematic perspective view of a portion of the gas sensor according to a ninth embodiment of the present disclosure, from which a lid portion has been removed; a schematic plan view of a portion of the gas sensor according to a tenth embodiment of the present disclosure, from which a lid portion has been removed; and a schematic perspective view of a portion of the gas sensor according to an eleventh embodiment of the present disclosure, from which a lid portion has been removed.

[0012] An example of the present disclosure will now be described with reference to the accompanying drawings. The following description is essentially merely illustrative and is not intended to limit the present disclosure, its applications, or its uses. The drawings are schematic, and the dimensional ratios and the like do not necessarily correspond to reality. In the following description, terms indicating specific directions or positions (e.g., terms including "upper," "lower," "right," "left," "front," and "rear") may be used as necessary. The present specification and drawings define the X, Y, and Z directions. The Z direction is the thickness direction of the gas sensor, and the X and Y directions are directions perpendicular to the thickness direction of the gas sensor. The X and Y directions intersect each other (orthogonal in the present specification and drawings). The X direction is an example of a first direction, the Y direction is an example of a second direction, and the Z direction is an example of an orthogonal direction. The use of the terms indicating specific directions or positions described above is intended to facilitate understanding of the present disclosure with reference to the drawings, and the meanings of these terms do not limit the technical scope of the present disclosure.

[0013] <First embodiment> Fig. 1 is a schematic perspective view of a gas sensor according to a first embodiment of the present disclosure. Fig. 2 is a schematic perspective view of a portion of the gas sensor according to the first embodiment of the present disclosure, with a lid portion removed.

[0014] The gas sensor 10 shown in FIGS. 1 and 2 is for detecting a gas concentration. In the first embodiment, the gas sensor 10 is a thermal conduction type. However, the gas sensor 10 is not limited to a thermal conduction type, and may be of another type, such as a capacitance type. The gas sensor 10 can be used in various technical fields. For example, the gas sensor 10 may be installed indoors to detect the gas concentration therein, or may be used to control an internal combustion engine of an automobile or the like.

[0015] As shown in FIGS. 1 and 2, the gas sensor 10 includes a substrate 20, a detection element 30, a circuit element 40, an inner wall 50, an outer wall 60, and a lid portion 70.

[0016] In the first embodiment, the substrate 20 has a rectangular parallelepiped shape that is thin in the Z direction. That is, in the first embodiment, the substrate 20 has a quadrilateral shape in a plan view seen along the Z direction. Note that the shape of the substrate 20 is not limited to a rectangular parallelepiped shape (a quadrilateral shape seen along the Z direction). For example, the substrate 20 may have a polygonal shape other than a quadrilateral shape when seen along the Z direction.

[0017] In the first embodiment, the substrate 20 is a rigid substrate made of glass epoxy, ceramic, or the like, but is not limited to this. For example, the substrate 20 may be a lead frame.

[0018] 2, the detection element 30 is supported on a support surface 20A of the substrate 20. The support surface 20A is one of a pair of main surfaces, front and back, of the substrate 20, and faces in the Z direction.

[0019] The detection element 30 is a thermal conduction element that detects gas concentration by utilizing differences in thermal conductivity depending on the gas concentration. The detection element 30 has a detection unit 31. The detection unit 31 is exposed to the outside of the detection element 30. As a result, the detection unit 31 is exposed to the detection chamber 11, which will be described later. When gas in the detection chamber 11 comes into contact with the detection unit 31, the amount of heat dissipated from the detection unit 31 to the detection chamber 11 changes depending on the thermal conductivity depending on the concentration of the gas, causing a change in the temperature of the detection unit 31. This changes the resistance value of the detection unit 31. The gas concentration can be detected based on the change in the resistance value of the detection unit 31. The calculation of the gas concentration value may be performed in the detection element 30, or may be performed outside the detection element 30, for example, in a circuit element 40, which will be described later.

[0020] The detection element 30 may be an element that detects the gas concentration using a method other than the thermal conduction method, such as a capacitance method.

[0021] The circuit element 40 is supported on the support surface 20A of the substrate 20. In the first embodiment, the circuit element 40 is an element having wired logic whose program cannot be rewritten. For example, the circuit element 40 is an element having an application specific integrated circuit (ASIC). The circuit element 40 is not limited to an element having wired logic whose program cannot be rewritten. For example, the circuit element 40 may have an arithmetic unit that works in cooperation with software to realize a predetermined function.

[0022] The detection element 30 and the circuit element 40 are electrically connected to each other. The detection element 30 is electrically connected to the substrate 20 via a bonding wire 32. The circuit element 40 is electrically connected to the substrate 20 via a bonding wire 41. The bonding wires 32 and 41 are electrically connected to each other via a conductive wiring pattern (not shown) formed on the substrate 20. As a result, a signal corresponding to the gas concentration detected by the detection element 30 is transmitted from the detection element 30 to the circuit element 40. Note that the signal corresponding to the gas concentration may represent the gas concentration, or may represent something other than the gas concentration (for example, the resistance value of the detection unit 31).

[0023] The detection element 30 and the circuit element 40 may be electrically connected to the substrate 20 by means other than bonding wires. For example, the detection element 30 and the circuit element 40 may be mounted on the substrate 20 by flip chip mounting. In this case, the detection element 30 and the circuit element 40 are electrically connected to the substrate 20 by solder. Alternatively, the detection element 30 and the circuit element 40 may be electrically connected directly without going through the substrate 20.

[0024] The circuit element 40 includes a signal processing circuit (not shown) that processes the signal corresponding to the gas concentration output from the detection element 30. For example, in the first embodiment, the circuit element 40 includes a converter, a filter, a temperature sensor, a processor, a memory, and the like. The converter converts the voltage signal output from the detection element 30 into a digital signal. The filter filters the digital signal from the converter. The temperature sensor detects temperature. The processor corrects the filtered digital signal based on the temperature detected by the temperature sensor. The memory stores correction coefficients and the like used when correcting the digital signal using the detected temperature.

[0025] The signal processed by the circuit element 40 is output to the outside of the gas sensor 10 via an external connection terminal (not shown) provided on the substrate 20 .

[0026] In the first embodiment, the detection element 30 and the circuit element 40 are each directly supported by the substrate 20. However, the detection element 30 and the circuit element 40 may be indirectly supported by the substrate 20. For example, the circuit element 40 may be supported by the substrate 20, and the detection element 30 may be supported by the circuit element 40. That is, the detection element 30 may be indirectly supported by the substrate 20 via the circuit element 40. Conversely to the above, the detection element 30 may be supported by the substrate 20, and the circuit element 40 may be supported by the detection element 30. That is, the circuit element 40 may be indirectly supported by the substrate 20 via the detection element 30. In this case, the circuit element 40 is supported by a portion of the detection element 30 other than the detection portion 31.

[0027] The circuit element 40 may be supported on a surface different from the support surface 20A, for example, on the back surface of the substrate 20 opposite to the support surface 20A. The gas sensor 10 may not include the circuit element 40. In this case, a signal corresponding to the gas concentration output from the gas sensor 10 is input to a circuit element provided outside the gas sensor 10. The circuit element processes the input signal as described above.

[0028] The inner wall 50 is supported by the support surface 20A of the substrate 20. When viewed along the Z direction perpendicular to the support surface 20A, the inner wall 50 surrounds the detection element 30 and the circuit element 40. When viewed along the Z direction, the space surrounded by the inner wall 50 is the detection chamber 11. The detection element 30 and the circuit element 40 are provided in the detection chamber 11.

[0029] In the first embodiment, the inner wall 50 is rectangular when viewed along the Z direction. The inner wall 50 has a first wall 51, a second wall 52, and third walls 53 and 54. The first wall 51, the second wall 52, and the third walls 53 and 54 correspond to the sides of the rectangle, respectively. The first wall 51 and the second wall 52 extend along the Y direction and face each other in the X direction. The third walls 53 and 54 extend along the X direction and face each other in the Y direction. The third wall 53 connects one end of the first wall 51 and the second wall 52 to each other in the Y direction. The third wall 54 connects the other end of the first wall 51 and the second wall 52 to each other in the Y direction.

[0030] The third walls 53, 54 each have at least one inner hole 50A. In the first embodiment, the third walls 53, 54 each have a total of two inner holes 50A. The number of inner holes 50A may be other than two. On the other hand, the first wall 51 and the second wall 52 do not have an inner hole 50A.

[0031] The inner hole 50A has at least one first-side hole 50Aa provided in the third wall 53 and at least one second-side hole 50Ab provided in the third wall 54. In the first embodiment, one first-side hole 50Aa and one second-side hole 50Ab are provided. Note that the number of first-side holes 50Aa may be other than one, and the number of second-side holes 50Ab may be other than one. The first-side hole 50Aa and the second-side hole 50Ab sandwich the detection unit 31 of the detection element 30 in the Y direction. In other words, the first-side hole 50Aa is located on one side of the detection unit 31 in the Y direction, and the second-side hole 50Ab is located on the other side of the detection unit 31 in the Y direction.

[0032] The inner hole 50A penetrates the third walls 53 and 54 in the Y direction. More specifically, the one side hole 50Aa penetrates the third wall 53 in the Y direction, and the other side hole 50Ab penetrates the third wall 54 in the Y direction. This allows the flow path 12 and the detection chamber 11 to communicate with each other via the inner hole 50A (i.e., the one side hole 50Aa and the other side hole 50Ab).

[0033] The inner hole 50A may be provided in only one of the third walls 53, 54. For example, the third wall 53 may have one one-side hole 50Aa, while the third wall 54 may not have any other-side hole 50Ab. Also, for example, the third wall 54 may have three other-side holes 50Ab, while the third wall 53 may not have any one-side hole 50Aa.

[0034] The outer wall 60 is supported by the support surface 20A of the substrate 20. When viewed along the Z direction, the outer wall 60 surrounds the inner wall 50. When viewed along the Z direction, the space between the inner wall 50 and the outer wall 60 is the flow path 12.

[0035] The outer wall 60 has at least one first outer hole 60A and at least one second outer hole 60B. In the first embodiment, the outer wall 60 has two first outer holes 60A and two second outer holes 60B. Note that the number of first outer holes 60A may be other than two, and the number of second outer holes 60B may be other than two. The first outer hole 60A and the second outer hole 60B sandwich the detection chamber 11 in the X direction. In other words, the second outer hole 60B is provided on the opposite side of the detection chamber 11 from the first outer hole 60A in the X direction.

[0036] The first outer hole 60A and the second outer hole 60B penetrate the outer wall 60 in the X direction. That is, the direction in which the first outer hole 60A and the second outer hole 60B penetrate the outer wall 60 is different from the direction in which the inner hole 50A penetrates the inner wall 50. As a result, the outside of the outer wall 60 (in other words, the outside of the gas sensor 10) and the flow path 12 are in communication with each other via the first outer hole 60A and the second outer hole 60B.

[0037] The first outer hole 60A faces the first wall 51 in the X direction. The second outer hole 60B faces the second wall 52 in the X direction. In other words, each of the first outer hole 60A and the second outer hole 60B faces in the X direction a wall of the inner wall 50 that does not have the inner hole 50A.

[0038] 1 , the lid portion 70 is supported by the inner wall 50 and the outer wall 60. As a result, the lid portion 70 closes the detection chamber 11 and the flow path 12. The detection chamber 11 is a space defined by the support surface 20A of the substrate 20, the inner wall 50, and the lid portion 70. The flow path 12 is a space defined by the support surface 20A of the substrate 20, the inner wall 50, the outer wall 60, and the lid portion 70.

[0039] An insulating material is preferable as the material for the inner wall 50, the outer wall 60, and the lid portion 70. In this embodiment, the inner wall 50, the outer wall 60, and the lid portion 70 are made of a hard resin such as a thermosetting resin, but they may be made of a material other than a hard resin.

[0040] Hereinafter, the flow of gas in the gas sensor 10 according to the first embodiment will be described with reference to FIG.

[0041] 2 , when gas flows around the installed gas sensor 10 from the first outer hole 60A to the second outer hole 60B along the X direction, the gas enters the interior of the gas sensor 10 from the outside through the first outer hole 60A. The gas that enters the interior of the gas sensor 10 is blocked by the first wall 51 of the inner wall 50, so it changes direction from the X direction to the Y direction and travels along the flow path 12. The gas traveling through the flow path 12 along the Y direction changes direction from the Y direction to the X direction at a corner of the flow path 12. A portion of the gas traveling through the flow path 12 along the X direction enters the detection chamber 11 through the inner hole 50A. The remaining portion of the gas traveling along the flow path 12 does not enter the detection chamber 11, but travels through the flow path 12 toward the second outer hole 60B and is released from the interior of the gas sensor 10 to the outside through the second outer hole 60B.

[0042] A portion of the gas traveling along the flow path 12 enters the detection chamber 11 through one of the one side hole 50Aa and the other side hole 50Ab, and is released from the detection chamber 11 to the flow path 12 through the other of the one side hole 50Aa and the other side hole 50Ab. Whether the gas enters the detection chamber 11 through the one side hole 50Aa or the other side hole 50Ab depends on the arrangement angle of the gas sensor 10 relative to the direction of gas flow, the dimensional accuracy of the flow path 12 in the gas sensor 10, and the like.

[0043] When the gas that has entered the detection chamber 11 comes into contact with the detection portion 31 of the detection element 30, the temperature of the detection portion 31 changes, and the resistance value of the detection portion 31 changes.

[0044] The gas released from the detection chamber 11 to the flow path 12 travels through the flow path 12 toward the second outer hole 60B and is released to the outside of the gas sensor 10 through the second outer hole 60B.

[0045] When gas flows from the second outer hole 60B to the first outer hole 60A along the X direction, the gas enters the gas sensor 10 from the outside to the inside through the second outer hole 60B, and is released from the inside to the outside of the gas sensor 10 through the first outer hole 60A.

[0046] According to the first embodiment, the inner hole 50A is penetrated in a direction different from that of the first outer hole 60A and the second outer hole 60B. As a result, the gas that flows into the flow path 12 from at least one of the first outer hole 60A and the second outer hole 60B changes direction before reaching the detection unit 31 provided in the detection chamber 11 via the inner hole 50A. As a result, the speed of the gas decreases, and fluctuations in the flow rate and direction of the gas entering the detection chamber 11 can be reduced. This reduces the effect of these fluctuations on the detection unit 31, and prevents a decrease in the detection accuracy of the detection unit 31.

[0047] According to the first embodiment, the outer wall 60 surrounds the inner wall 50 when viewed along the Z direction, and the flow path 12 through which the gas passes is formed by utilizing the gap between the outer wall 60 and the inner wall 50. Therefore, it is possible to prevent the gas sensor 10 from becoming large.

[0048] According to the first embodiment, gas can be made to flow into the detection chamber 11 through one of the one side hole 50Aa and the other side hole 50Ab, and can be made to flow out of the detection chamber 11 through the other of the one side hole 50Aa and the other side hole 50Ab. This makes it possible to reduce gas accumulation in the detection chamber 11.

[0049] According to the first embodiment, the first wall 51 and the second wall 52 prevent the gas flowing into the flow path 12 from reaching the detection unit 31 in a straight line. This reduces the effect of fluctuations in the flow rate and direction of the gas on the detection unit 31, thereby preventing a decrease in the detection accuracy of the detection unit 31. <Modifications> At least one of the inner wall 50 and the outer wall 60 and the lid 70 may contain a metal material such as aluminum. For example, at least one of the inner wall 50 and the outer wall 60 and the lid 70 may be made of a metal rather than an insulating material. Furthermore, for example, a metal film may be attached to the outer surfaces of the outer wall 60 and the lid 70 facing the outside of the gas sensor 10. Furthermore, for example, the inner wall 50, the outer wall 60, and the lid 70 may be made of a mixture of a metal material and another type of material such as a resin.

[0050] According to this modification, at least one of the inner wall 50 and the outer wall 60 and the lid 70 can function as an electromagnetic shield, thereby improving the resistance of the detection element 30 to electrostatic discharge (ESD).

[0051] In the first embodiment, the substrate 20, the inner wall 50, and the outer wall 60 are separate members. However, the substrate 20, the inner wall 50, and the outer wall 60 may be integrally formed. For example, the substrate 20 including the inner wall 50 and the outer wall 60 is formed in multiple layers, and the detection chamber 11 and the flow channel 12 are formed by photolithography, polishing, or the like.

[0052] According to this modification, the inner wall 50 and the outer wall 60 are integrally formed with the substrate 20. Therefore, the stress resistance of the gas sensor 10 can be improved compared to a configuration in which the inner wall 50 and the outer wall 60 are separate members from the substrate 20.

[0053] According to this modification, the manufacturing process of the gas sensor 10 does not require the step of attaching the inner wall 50 and the outer wall 60 to the substrate 20. In particular, when a plurality of inner walls 50 and a plurality of outer walls 60 are attached to a large substrate on which a plurality of substrates 20 are arranged, and then the large substrate is cut to manufacture a plurality of gas sensors 10, the elimination of the above step has a significant effect in simplifying the manufacturing process.

[0054] 3 is a schematic perspective view of a gas sensor according to a second embodiment of the present disclosure. The gas sensor 10A according to the second embodiment differs from the gas sensor 10 according to the first embodiment in that a cover hole 70A is provided. The differences from the first embodiment will be described below.

[0055] In the description of the second and subsequent embodiments, the same reference numerals are used to designate commonalities with the gas sensor 10 according to the first embodiment, and their description will be omitted in principle, but will be mentioned only when necessary.

[0056] As shown in FIG. 3 , the lid portion 70 has at least one lid hole 70A. In the second embodiment, the lid portion 70 has four lid holes 70A, but the number of lid holes 70A is not limited to four. Each lid hole 70A penetrates the lid portion 70 in the Z direction and connects the outside of the gas sensor 10A to the flow path 12. Each lid hole 70A is located at a vertex of the flow path 12 extending along a side of a rectangle when viewed in the Z direction. Note that the position of each lid hole 70A is not limited to the position shown in FIG. 3 .

[0057] According to the second embodiment, the outside of the gas sensor 10A is connected to the flow path 12 by the cover hole 70A in addition to the first outer hole 60A and the second outer hole 60B. This improves the gas exchangeability between the outside of the gas sensor 10A and the flow path 12.

[0058] The gas sensor is preferably positioned so that the hole for introducing gas faces upstream in the direction of gas flow around the gas sensor. According to the second embodiment, the gas sensor 10A is preferably positioned so that any one of the first outer hole 60A, the second outer hole 60B, and the cover hole 70A faces upstream in the direction of gas flow. On the other hand, in the case of a configuration such as the gas sensor 10 according to the first embodiment, which does not include the cover hole 70A, the gas sensor 10 is preferably positioned so that any one of the first outer hole 60A and the second outer hole 60B faces upstream in the direction of gas flow. In other words, according to the second embodiment, the presence of the cover hole 70A increases the number of desirable positions for the gas sensor 10A compared to the gas sensor 10 according to the first embodiment. In other words, according to the second embodiment, the flexibility in the positioning of the gas sensor 10A can be increased.

[0059] 4 is a schematic plan view of a gas sensor according to a third embodiment of the present disclosure, excluding a lid portion. The gas sensor 10B according to the third embodiment differs from the gas sensor 10 according to the first embodiment in that it includes a substrate hole 20B. The differences from the first embodiment will be described below.

[0060] As shown in FIG. 4 , the substrate 20 has at least one substrate hole 20B. In the third embodiment, the substrate 20 has three substrate holes 20B, but the number of substrate holes 20B is not limited to three. Each substrate hole 20B penetrates the substrate 20 in the Z direction and connects the outside of the gas sensor 10B to the detection chamber 11. Each substrate hole 20B is located at one of three corners of the rectangular detection chamber 11 when viewed along the Z direction. Note that the positions of each substrate hole 20B are not limited to those shown in FIG. 4 .

[0061] According to the third embodiment, the inside of the detection chamber 11 is connected to the outside of the gas sensor 10B by the substrate hole 20B in addition to the inner hole 50A, so that the gas that has entered the detection chamber 11 from the inner hole 50A can be easily released to the outside of the gas sensor 10B.

[0062] Typically, the substrate 20 is supported on an apparatus in which the gas sensor 10B is installed. Therefore, even if the gas sensor 10B has a substrate hole 20B, the inflow of gas from the outside of the gas sensor 10B into the detection chamber 11 through the substrate hole 20B, i.e., the inflow of gas into the detection chamber 11 without passing through the flow path 12, is suppressed to a minimum.

[0063] 5 is a schematic plan view of a gas sensor according to a fourth embodiment of the present disclosure, excluding a lid portion. The gas sensor 10C according to the fourth embodiment differs from the gas sensor 10 according to the first embodiment in that it further includes a filter film 80. The differences from the first embodiment will be described below.

[0064] As shown in Fig. 5, a filter membrane 80 is attached to the outer wall 60. The filter membrane 80 blocks the first outer holes 60A and the second outer holes 60B. The filter membrane 80 limits what can pass through the first outer holes 60A and the second outer holes 60B to those smaller than a specific size. For example, the filter membrane 80 may be a mesh membrane or a semipermeable membrane that blocks the passage of liquids while allowing the passage of gases.

[0065] 5, the filter film 80 is attached to the outer surface of the outer wall 60, but the filter film 80 may be attached to the inner surface of the outer wall 60 (in other words, the surface of the outer wall 60 facing the inner wall 50). In FIG. 5, the gas sensor 10C includes a filter film 80 that blocks the first outer hole 60A and a filter film 80 that blocks the second outer hole 60B, but the gas sensor 10C may include only one of the filter film 80 that blocks the first outer hole 60A and the filter film 80 that blocks the second outer hole 60B. In other words, both the first outer hole 60A and the second outer hole 60B may be blocked by the filter film 80, or only one of the first outer hole 60A and the second outer hole 60B may be blocked by the filter film 80.

[0066] According to the fourth embodiment, while gas is allowed to flow into the flow path 12 from the outside of the gas sensor 10C through the first outer hole 60A and the second outer hole 60B, the filter membrane 80 can reduce the intrusion of foreign matter other than the gas into the flow path 12 from the outside of the gas sensor 10C through the first outer hole 60A and the second outer hole 60B.

[0067] 6 is a schematic plan view of a gas sensor according to a fifth embodiment of the present disclosure, excluding a lid portion. The gas sensor 10D according to the fifth embodiment differs from the gas sensor 10 according to the first embodiment in that the flow path 12 includes an expanded path 12A. The differences from the first embodiment will be described below.

[0068] 6, the flow path 12 has an enlarged path 12A in which the cross-sectional area of ​​the flow path 12 increases toward the inner hole 50A. In the fifth embodiment, the enlarged path 12A is provided in a portion of the flow path 12 that extends along the X direction, but this is not limited thereto. For example, the enlarged path 12A may be provided throughout the entire flow path 12, including the portion of the flow path 12 that extends along the Y direction.

[0069] The cross-sectional area of ​​the flow path 12 is the area of ​​a cross section perpendicular to the direction in which the flow path 12 extends. In the fifth embodiment, the cross-sectional area of ​​the expanded path 12A is the area of ​​a YZ cross section of the expanded path 12A. In the configuration shown in FIG. 6 , the third wall 53 and the third wall 54 each have inclined surfaces 53A and 54A that slope in the Y direction as they approach the inner hole 50A along the X direction. As a result, as described above, the cross-sectional area of ​​the expanded path 12A increases as they approach the inner hole 50A. Note that the configuration for realizing the expanded path 12A is not limited to the inclined surfaces 53A and 54A. For example, the outer wall 60 may have an inclined inner surface. Furthermore, for example, the surfaces of the inner wall 50 and the outer wall 60 facing the expanded path 12A may be stepped, so that the cross-sectional area of ​​the expanded path 12A increases stepwise as they approach the inner hole 50A.

[0070] According to the fifth embodiment, the speed of gas entering the flow path 12 from outside the gas sensor 10D decreases as the gas passes through the enlarged path 12A and approaches the inner bore 50A. This reduces the speed of gas entering the detection chamber 11 through the inner bore 50A. As a result, the effect of fluctuations in the gas flow rate on the detection unit 31 can be reduced, thereby preventing a decrease in the detection accuracy of the detection unit 31.

[0071] 7 is a schematic plan view of a gas sensor according to a sixth embodiment of the present disclosure, excluding a lid portion. The gas sensor 10E according to the sixth embodiment differs from the gas sensor 10 according to the first embodiment in that the flow path 12 includes a narrowed path 12B. The differences from the first embodiment will be described below.

[0072] 7, the flow path 12 has a narrowing path 12B in which the cross-sectional area of ​​the flow path 12 becomes smaller as it approaches the inner hole 50A. As in the fifth embodiment, the narrowing path 12B is provided in a portion of the flow path 12 that extends along the X direction, but this is not limiting.

[0073] As in the fifth embodiment, the cross-sectional area of ​​flow path 12 is the area of ​​a cross section perpendicular to the extension direction of flow path 12. In the configuration shown in Fig. 7, third wall 53 and third wall 54 each have inclined surfaces 53B and 54B that incline in the Y direction as they approach inner bore 50A along the X direction. As a result, as described above, the cross-sectional area of ​​reduced passage 12B decreases as they approach inner bore 50A. Note that, as in the fifth embodiment, the configuration for realizing reduced passage 12B is not limited to inclined surfaces 53B and 54B.

[0074] According to the sixth embodiment, the speed of gas that has entered the flow path 12 from outside the gas sensor 10E increases as the gas passes through the reduced passage 12B and approaches the inner bore 50A. As a result, if a foreign object enters the flow path 12 from outside the gas sensor 10E, the foreign object is transported at high speed along the flow path 12. As a result, it is possible to reduce the possibility that the foreign object moving along the flow path 12 will change direction and enter the detection chamber 11 via the inner bore 50A.

[0075] 8 is a schematic plan view of a gas sensor according to a seventh embodiment of the present disclosure, excluding a lid portion. The gas sensor 10F according to the seventh embodiment differs from the gas sensor 10 according to the first embodiment in that the corners of the inner wall 50 that defines the detection chamber 11 are curved. The differences from the first embodiment will be described below.

[0076] As shown in FIG. 8 , when viewed along the Z direction, the surface 50B of the inner wall 50 that defines the detection chamber 11 is a rectangle. The four vertices of the rectangle defined by the surface 50B are four boundary portions 50Ba between two adjacent walls among the first wall 51, the second wall 52, the third wall 53, and the third wall 54. The four boundary portions 50Ba are the boundary portion between the first wall 51 and the third wall 53, the boundary portion between the first wall 51 and the third wall 54, the boundary portion between the second wall 52 and the third wall 53, and the boundary portion between the second wall 52 and the third wall 54. In the seventh embodiment, all of the four boundary portions 50Ba are curved surfaces. Note that only a portion of the four boundary portions 50Ba may be curved surfaces. In other words, at least one of the boundary portion between the first wall 51 and the third walls 53, 54 and the boundary portion between the second wall 52 and the third walls 53, 54 is a curved surface.

[0077] 8, the corners of the inner wall 50 and the outer wall 60 that define the flow path 12 are not curved. However, the corners of the inner wall 50 that defines the flow path 12 may be curved, or the corners of the outer wall 60 that defines the flow path 12 may be curved.

[0078] If the four boundary portions 50Ba described above among the surfaces of the inner wall 50 that define the detection chamber 11 were bent rather than curved, there is a risk that the gas that flows into the detection chamber 11 would become turbulent near the bent portions. According to the seventh embodiment, among the surfaces of the inner wall 50 that define the detection chamber 11, at least one of the boundary portion 50Ba between the first wall 51 and the third wall 53 and the boundary portion 50Ba between the second wall 52 and the third walls 53, 54 is a curved surface. This makes it possible to reduce the turbulence.

[0079] 9 is a schematic plan view of a gas sensor according to an eighth embodiment of the present disclosure, excluding a lid portion. The gas sensor 10G according to the eighth embodiment differs from the gas sensor 10 according to the first embodiment in that a rib or a groove is provided in the flow path 12. The differences from the first embodiment will be described below.

[0080] As shown in FIG. 9, the gas sensor 10G has ribs 91A and 91B protruding from a support surface 20A of a substrate 20.

[0081] The rib 91A is provided along the direction in which the flow path 12 extends. In the configuration shown in Fig. 9, the rib 91A is provided around the entire circumference of the flow path 12, but it may also be provided around a portion of the flow path 12. The rib 91A only needs to extend along the flow path 12 from at least one of the first outer hole 60A and the second outer hole 60B to the inner hole 50A. For example, the rib 91A may extend along the flow path 12 from the first outer hole 60A to the inner hole 50A of the flow path 12, but may not be provided between the second outer hole 60B and the inner hole 50A of the flow path 12.

[0082] 9, the gas sensor 10G includes two ribs 91A. The two ribs 91A are spaced apart in the width direction of the flow path 12. The number of ribs 91A is not limited to two. The width direction of the flow path 12 is perpendicular to the direction in which the flow path 12 extends and perpendicular to the Z direction.

[0083] The rib 91B is provided in the inner hole 50A. The rib 91B is provided continuous with the rib 91A. The rib 91B extends from the flow path 12 toward the detection chamber 11 along the penetration direction of the inner hole 50A (the Y direction in FIG. 9 ).

[0084] 9, the gas sensor 10G includes one rib 91B. However, the gas sensor 10G may include multiple ribs 91B. The multiple ribs 91B are provided at intervals in a direction perpendicular to the penetration direction of the inner hole 50A.

[0085] The gas sensor 10G may include grooves 92A, 92B recessed from the support surface 20A of the substrate 20, instead of the ribs 91A, 91B. The groove 92A, like the rib 91A, is provided along the direction in which the flow path 12 extends, and extends from at least one of the first outer hole 60A and the second outer hole 60B to the inner hole 50A along the flow path 12. The groove 92B, like the rib 91B, is provided contiguous to the groove 92A in the inner hole 50A, and extends from the flow path 12 toward the detection chamber 11 along the penetration direction of the inner hole 50A.

[0086] 9, the ribs 91A, 91B and grooves 92A, 92B are provided on the substrate 20, but this is not limiting. The ribs 91A, 91B and grooves 92A, 92B may be provided on the inner wall 50, the outer wall 60, or the lid portion 70.

[0087] According to the eighth embodiment, the ribs 91A and the grooves 92A can make the direction of gas flow in the flow passage 12 closer to a constant direction. That is, the gas flow in the flow passage 12 can be rectified.

[0088] According to the eighth embodiment, the ribs 91B and the grooves 92B can make the gas flow direction in the inner hole 50A closer to a constant direction, thereby allowing the gas rectified in the flow path 12 to be guided to the detection chamber 11 through the inner hole 50A while maintaining the rectified state.

[0089] 10 is a schematic perspective view of a gas sensor according to a ninth embodiment of the present disclosure, with the lid removed. The gas sensor 10H according to the ninth embodiment differs from the gas sensor 10 according to the first embodiment in that the inner wall 50 is supported by the detection element 30. The differences from the first embodiment will be described below.

[0090] 10 , in the gas sensor 10H, the inner wall 50 is supported by the detection element 30. That is, in the ninth embodiment, the inner wall 50 is supported by the substrate 20 via the detection element 30. In other words, the inner wall 50 is indirectly supported by the substrate 20. On the other hand, in the first embodiment, the inner wall 50 is directly supported by the substrate 20. In the ninth embodiment, the detection chamber 11 is a space defined by the detection element 30, the inner wall 50, and the lid portion 70. Note that in the ninth embodiment, the inner wall 50 surrounds the detection portion 31 when viewed along the Z direction, and therefore the detection portion 31 is located in the detection chamber 11.

[0091] 10 may include a circuit element 40. In this case, the circuit element 40 may be supported by the detection element 30, or may be supported on the back side of the substrate 20 opposite to the support surface 20A.

[0092] According to the ninth embodiment, the area of ​​the gas sensor 10H when viewed along the Z direction can be made smaller than in a configuration in which the inner wall 50 and the detection element 30 are individually supported by the substrate 20. In other words, the gas sensor 10H can be made smaller.

[0093] According to the ninth embodiment, when a gap is generated in a part between the inner wall 50 and the detection element 30, the gap can be made to function as an inner hole that communicates between the flow path 12 and the detection chamber 11. This can improve the exchangeability of gas between the inside and outside of the detection chamber 11.

[0094] 11 is a schematic plan view of a gas sensor according to a tenth embodiment of the present disclosure, excluding a lid portion. The gas sensor 10I according to the tenth embodiment differs from the gas sensor 10 according to the first embodiment in that the circuit element 40 forms part of the inner wall 50 and defines the inner hole 50A. The differences from the first embodiment will be described below.

[0095] 11 , in the gas sensor 10I, the circuit element 40 forms a part of the inner wall 50 and defines an inner hole 50A. In the configuration shown in FIG. 11 , the circuit element 40 forms a part of the third wall 53. The third wall 53 has two one-side holes 50Aa. The circuit element 40 defines the two one-side holes 50Aa.

[0096] According to the tenth embodiment, the circuit element 40 constitutes a part of the inner wall 50. As a result, the entire circuit element 40 is located in the detection chamber 11, and the area of ​​the gas sensor 10I when viewed along the Z direction can be made smaller than in a configuration in which the circuit element 40 is not a part of the inner wall 50. In other words, the gas sensor 10I can be made smaller.

[0097] According to the tenth embodiment, the circuit element 40 partitions the inner hole 50A, which makes it easy to make the inner hole 50A large, thereby improving the exchangeability of gas between the inside and outside of the detection chamber 11.

[0098] 12 is a schematic perspective view of a gas sensor according to an eleventh embodiment of the present disclosure, with the cover removed. The gas sensor 10J according to the eleventh embodiment differs from the gas sensor 10 according to the first embodiment in that the gas sensor 10J includes a covering. The differences from the first embodiment will be described below.

[0099] 12, the gas sensor 10J includes a covering portion 25. The covering portion 25 is provided on the support surface 20A of the substrate 20.

[0100] The covering portion 25 is made of an insulating material. For example, like the inner wall 50, the outer wall 60, and the lid portion 70, the covering portion 25 may be made of a hard resin such as a thermosetting resin, or may be made of a material other than a hard resin. The covering portion 25 may be made of the same material as the inner wall 50, the outer wall 60, and the lid portion 70, or may be made of a different material. For example, the covering portion 25 may be made of a resin, and the lid portion 70 may be made of a material other than a resin, such as a metal.

[0101] The covering portion 25 may be integrally formed with the inner wall 50 and the outer wall 60 .

[0102] The covering portion 25 may be a separate member from the inner wall 50 and the outer wall 60. In this case, as a configuration example, the inner wall 50 and the outer wall 60 may be supported by the support surface 20A, and the covering portion 25 may be provided on a portion of the support surface 20A where the inner wall 50 and the outer wall 60 are not provided. In another configuration example in this case, the covering portion 25 may be supported by the support surface 20A, and the inner wall 50 and the outer wall 60 may be supported by the covering portion 25. In other words, the inner wall 50 and the outer wall 60 may be supported on the substrate 20 via the covering portion 25.

[0103] The covering portion 25 covers the bonding wires 32 and 41. The bonding wires 32 and 41 are an example of a connecting portion.

[0104] The covering portion 25 may cover a part of the detection element 30. In the eleventh embodiment, the covering portion 25 covers the part of the detection element 30 other than the detection portion 31. In other words, the detection portion 31 is exposed to the detection chamber 11.

[0105] The covering portion 25 may cover at least a part of the circuit element 40. In the eleventh embodiment, the circuit element 40 has a temperature sensor 42, and the covering portion 25 covers the circuit element 40 except for the temperature sensor 42. In other words, the temperature sensor 42 is exposed to the detection chamber 11.

[0106] According to the eleventh embodiment, the bonding wires 32, 41 are covered with the covering portion 25. Therefore, the bonding wires 32, 41 can be protected from foreign matter such as water droplets.

[0107] The gas sensor described above can also be expressed as follows.

[0108] (1) A gas sensor according to one aspect of the present disclosure includes: a substrate; a detection element supported by the substrate and having a detection portion; an inner wall supported by the substrate and surrounding the detection portion when viewed in an orthogonal direction orthogonal to a support surface on which the substrate supports the detection element; an outer wall supported by the substrate and surrounding the inner wall when viewed in the orthogonal direction; and a lid supported by the inner wall and the outer wall, closing a detection chamber in which the detection portion is provided, which is a space inside the inner wall when viewed in the orthogonal direction, and closing a flow path that is a space between the inner wall and the outer wall when viewed in the orthogonal direction, wherein the outer wall has at least one first outer hole penetrating in a first direction to communicate an outside of the outer wall with the flow path, and at least one second outer hole provided on an opposite side of the first outer hole with respect to the detection chamber in the first direction and penetrating in the first direction to communicate an outside of the outer wall with the flow path, The inner wall has at least one inner hole penetrating in a second direction intersecting the first direction so as to connect the flow path and the detection chamber.

[0109] (2) In the gas sensor of (1), the inner hole may have at least one one-side hole located on one side of the detection portion in the second direction, and at least one other-side hole located on the other side of the detection portion in the second direction.

[0110] (3) In the gas sensor of (1) or (2), the inner wall may include: a first wall that does not have the inner hole and faces the first outer hole in the first direction; a second wall that does not have the inner hole and faces the second outer hole in the first direction; and a third wall that connects the first wall and the second wall and has the inner hole.

[0111] (4) In the gas sensor of (3), at least one of the boundary portion between the first wall and the third wall and the boundary portion between the second wall and the third wall among the surfaces of the inner wall that define the detection chamber may be a curved surface.

[0112] (5) In the gas sensor according to any one of (1) to (4), the lid portion may further include at least one lid hole that connects the outside of the gas sensor to the flow path.

[0113] (6) In the gas sensor according to any one of (1) to (5), the substrate may further include at least one substrate hole that connects the outside of the gas sensor to the detection chamber.

[0114] (7) The gas sensor according to any one of (1) to (6) may further include a filter film that closes an opening of at least one of the first outer hole and the second outer hole.

[0115] (8) In the gas sensor according to any one of (1) to (7), the flow path may have an expanding path in which the cross-sectional area of ​​the flow path increases toward the inner hole.

[0116] (9) In the gas sensor according to any one of (1) to (7), the flow path may have a narrowing path in which the cross-sectional area of ​​the flow path becomes smaller as it approaches the inner hole.

[0117] (10) The gas sensor according to any one of (1) to (9) may further include a rib or a groove provided in the flow path and extending along the flow path from at least one of the first outer hole and the second outer hole to the inner hole.

[0118] (11) In the gas sensor of (10), the rib or groove may be provided in the inner hole in addition to the flow path, or may extend continuously from the flow path toward the detection chamber along the inner hole.

[0119] (12) In the gas sensor according to any one of (1) to (11), the inner wall may be supported by the detection element.

[0120] (13) In the gas sensor according to any one of (1) to (12), at least one of the inner wall and the outer wall and the lid may contain a metal material.

[0121] (14) The gas sensor according to any one of (1) to (13) may further include a circuit element supported on the substrate, and the circuit element may form a part of the inner wall and define the inner hole.

[0122] (15) In the gas sensor according to any one of (1) to (14), the inner wall and the outer wall may be integrally formed with the substrate.

[0123] (16) The gas sensor according to any one of (1) to (15) may include a connection portion that electrically connects the detection element and the substrate, and a covering portion that is supported by the substrate and covers the connection portion.

[0124] Any of the various embodiments described above may be combined appropriately to achieve the effects of each of them.

[0125] While the present invention has been fully described in connection with preferred embodiments, with appropriate reference to the drawings, various changes and modifications will become apparent to those skilled in the art, and it is to be understood that such changes and modifications are included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

[0126] REFERENCE SIGNS LIST 10 Gas sensor 11 Detection chamber 12 Flow path 12A Enlarged path 12B Reduced path 20 Substrate 20A Support surface 20B Substrate hole 25 Covering portion 30 Detection element 31 Detection portion 32 Bonding wire 40 Circuit element 41 Bonding wire 50 Inner wall 50A Inner hole 50Aa One side hole 50Ab Other side hole 50B Surface partitioning the detection chamber 50Ba Boundary portion 51 First wall 52 Second wall 53 Third wall 54 Third wall 60 Outer wall 60A First outer hole 60B Second outer hole 70 Lid portion 70A Lid hole 80 Filter membrane 91A Rib 91B Rib 92A Groove 92B Groove

Claims

1. A substrate, a detection element supported by the substrate and having a detection unit, an inner wall supported by the substrate and surrounding the detection unit when viewed along an orthogonal direction orthogonal to a support surface on which the substrate supports the detection element, an outer wall supported by the substrate and surrounding the inner wall when viewed along the orthogonal direction, and a lid supported by the inner wall and the outer wall, closing a detection chamber in which the detection unit is provided, which is a space inside the inner wall when viewed along the orthogonal direction, and closing a flow path which is a space between the inner wall and the outer wall when viewed along the orthogonal direction, wherein the outer wall has at least one first outer hole penetrated in a first direction to communicate the outside of the outer wall with the flow path, and at least one second outer hole provided on the opposite side of the first outer hole with respect to the detection chamber in the first direction and penetrated in the first direction to communicate the outside of the outer wall with the flow path, The gas sensor, wherein the inner wall has at least one inner hole penetrating in a second direction intersecting the first direction so as to connect the flow path and the detection chamber.

2. A gas sensor as described in claim 1, wherein the inner hole has at least one one-side hole located on one side of the detection portion in the second direction, and at least one other-side hole located on the other side of the detection portion in the second direction.

3. A gas sensor as described in claim 1 or 2, wherein the inner wall comprises: a first wall that does not have the inner hole and faces the first outer hole in the first direction; a second wall that does not have the inner hole and faces the second outer hole in the first direction; and a third wall that connects the first wall and the second wall and has the inner hole.

4. A gas sensor as described in claim 3, wherein at least one of the surfaces of the inner wall that define the detection chamber, the boundary between the first wall and the third wall and the boundary between the second wall and the third wall, is a curved surface.

5. The gas sensor according to any one of claims 1 to 4, wherein the lid portion further comprises at least one lid hole that connects the outside of the gas sensor with the flow path.

6. The gas sensor according to any one of claims 1 to 5, wherein the substrate further comprises at least one substrate hole communicating the outside of the gas sensor with the detection chamber.

7. The gas sensor according to any one of claims 1 to 6, further comprising a filter film that closes an opening of at least one of the first outer hole and the second outer hole.

8. The gas sensor according to any one of claims 1 to 7, wherein the flow path has an expanding path in which the cross-sectional area of ​​the flow path increases toward the inner hole.

9. The gas sensor according to any one of claims 1 to 7, wherein the flow path has a narrowing path in which the cross-sectional area of ​​the flow path becomes smaller as it approaches the inner hole.

10. A gas sensor as described in any one of claims 1 to 9, further comprising a rib or groove provided in the flow path and extending along the flow path from at least one of the first outer hole and the second outer hole to the inner hole.

11. The gas sensor according to claim 10, wherein the rib or groove is provided in the inner hole in addition to the flow path, and extends continuously from the flow path toward the detection chamber along the inner hole.

12. The gas sensor according to any one of claims 1 to 11, wherein the inner wall is supported by the detection element.

13. The gas sensor according to any one of claims 1 to 12, wherein at least one of the inner wall and the outer wall and the lid portion contain a metal material.

14. The gas sensor according to any one of claims 1 to 13, further comprising a circuit element supported on the substrate, the circuit element constituting a part of the inner wall and defining the inner hole.

15. The gas sensor according to any one of claims 1 to 14, wherein the inner wall and the outer wall are integrally formed with the substrate.

16. The gas sensor according to any one of claims 1 to 15, comprising: a connection portion that electrically connects the detection element and the substrate; and a covering portion that is supported by the substrate and covers the connection portion.

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