Physical quantity detection device

Abstract

Provided is a physical quantity detection device capable of relaxing thermal stress acting on an injection molded member molded in a housing and improving reliability. The physical quantity detection device (100) includes a housing (110), a sub passage provided in the housing (110), a sensor portion that detects a physical quantity of a measured gas introduced into the sub passage, a circuit board on which the sensor portion is mounted, a circuit chamber that accommodates the circuit board, and an injection molded member (110a) that is injection molded in the circuit chamber to seal a back surface of the circuit board. The housing (110) has a stress relaxation wall (119c) that constitutes at least a portion of a non-planar portion (119b) included in an inner wall surface (119) that defines the circuit chamber. The stress relaxation wall (119c) has a thickness (T) that enables elastic deformation in response to a difference in thermal expansion between the injection molded member (110a) and the housing (110).

Description

Technical Field

[0001] This invention relates to a physical quantity detection device. Background Technology

[0002] In the prior art, there are known physical quantity detection devices for detecting the physical quantity of intake air in an internal combustion engine. The existing physical quantity detection device described in Patent Document 1 includes a housing protruding into a main passage through which the gas to be measured flows, a cover forming a secondary passage together with the housing, a support housed within the housing, and a sensor element supported by the support and disposed in the secondary passage.

[0003] The housing has an adhesive groove for applying an adhesive for bonding the cover. The adhesive groove has a first adhesive groove and a second adhesive groove. The first adhesive groove extends along the base end of the housing and, from the base end to a position closer to the front end of the housing than the support, extends along the protruding direction of the housing to apply the first adhesive. The second adhesive groove extends along a secondary passage to apply a second adhesive.

[0004] The existing physical quantity testing device is characterized in that the first adhesive has a higher Young's modulus than the second adhesive, and the second adhesive has higher thixotropy than the first adhesive (Patent Document 1, Abstract, etc.). According to this existing physical quantity testing device, even when using an epoxy adhesive with lower viscosity to improve the rigidity of the main body, the airtightness can be improved, achieving a balance between improved rigidity and improved airtightness.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2020 / 202723 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The housing of the physical quantity detection device, for example, has a circuit chamber for housing a circuit board. One side of the circuit board, for example, is equipped with a chip package, a pressure sensor, a humidity sensor, and circuit components, and is sealed with a silicone-based sealing component (Patent Document 1, paragraphs 0059 to 0062). The other side of the circuit board is sealed entirely, for example, by epoxy resin injection molding into the circuit chamber of the housing.

[0010] However, there are cases where the coefficient of linear expansion of the resin material constituting the housing differs from that of the injection-molded parts, such as epoxy resin, which are injection-molded within the circuit chamber of the housing. In such cases, the thermal stress generated by the expansion or contraction of the housing and the injection-molded parts due to temperature increases or decreases is concentrated in a portion of the injection-molded parts, posing a risk of reducing the reliability of the physical quantity detection device.

[0011] This invention provides a physical quantity detection device that can alleviate thermal stress on injection molded parts in a housing and improve reliability.

[0012] Methods for solving problems

[0013] One aspect of the present invention is a physical quantity detection device, comprising: a housing disposed in a main passage for the flow of a gas to be measured; a secondary passage disposed in the housing for taking in a portion of the gas to be measured from the main passage; a sensor unit for detecting a physical quantity of the gas to be measured taken in the secondary passage; a circuit board mounted on the front side of the sensor unit; a circuit chamber defined by an inner wall surface of the housing surrounding at least a portion of the circuit board to house the circuit board; and an injection molded part injected into the circuit chamber to seal the back side of the circuit board, wherein the housing has a stress-relieving wall constituting at least a portion of a non-planar portion included in the inner wall surface defining the circuit chamber, the stress-relieving wall having a thickness capable of elastically deforming in response to the thermal expansion difference between the injection molded part and the housing.

[0014] Invention Effects

[0015] According to one aspect of the present invention, a physical quantity detection device can be provided to alleviate thermal stress acting on an injection-molded part in a housing and improve reliability. Attached Figure Description

[0016] Figure 1 This is a system diagram illustrating one embodiment of the physical quantity detection device of the present invention.

[0017] Figure 2 yes Figure 1 Front view of the physical quantity detection device.

[0018] Figure 3 yes Figure 2 A front view of the injection molded part before injection molding of the physical quantity detection device.

[0019] Figure 4 yes Figure 1 The back view of the physical quantity detection device before the mounting cover.

[0020] Figure 5 yes Figure 1 Left side view of the physical quantity detection device.

[0021] Figure 6 yes Figure 1 The right side view of the physical quantity detection device.

[0022] Figure 7 yes Figure 2VII-VII cross-sectional view of the physical quantity detection device.

[0023] Figure 8 yes Figure 2 The VIII-VIII cross-sectional view of the physical quantity detection device.

[0024] Figure 9 It means Figure 1 A front view of a modified example 1 of a physical quantity detection device.

[0025] Figure 10 It means Figure 1 A front view of a modified example 2 of the physical quantity detection device.

[0026] Figure 11 It means Figure 1 A front view of a modified example 3 of the physical quantity detection device.

[0027] Figure 12 It means Figure 1 A front view of a modified example 4 of the physical quantity detection device.

[0028] Figure 13 It means Figure 1 A front view of a modified example 5 of a physical quantity detection device.

[0029] Figure 14 It means Figure 1 A front view of a modified example 6 of a physical quantity detection device.

[0030] Figure 15 It means Figure 1 A front view of a modified example 7 of a physical quantity detection device.

[0031] Figure 16 It means Figure 1 A front view of a modified example 8 of a physical quantity detection device.

[0032] Figure 17 It means Figure 1 A front view of a modified example 9 of a physical quantity detection device. Detailed Implementation

[0033] Hereinafter, embodiments of the physical quantity detection device of the present invention will be described with reference to the accompanying drawings.

[0034] Figure 1 This is a system diagram illustrating one embodiment of the physical quantity detection device of the present invention. The physical quantity detection device 100 of this embodiment is used, for example, in an internal combustion engine control system 1 using electronic fuel injection. The internal combustion engine control system 1 includes, for example, an internal combustion engine 10, the physical quantity detection device 100, a throttle valve 25, a throttle valve angle sensor 26, an idle air control valve 27, an oxygen sensor 28, and a control device 4.

[0035] The physical quantity detection device 100 is inserted into the interior of the main passage 22, for example, through a mounting hole provided in the wall of the main passage 22 (i.e., the passage for gas intake), and fixed to the passage wall of the main passage 22, thereby being installed in the main passage 22 through which the intake air, which is the gas to be measured 2, flows. The physical quantity detection device 100 takes in a portion of the gas to be measured 2 that is introduced through the air filter 21 and flows in the main passage 22, detects the physical quantity of the taken-in gas to be measured 2, and outputs it to the control device 4.

[0036] The physical quantity detection device 100 protrudes radially inward from the passage wall of the main passage 22 toward the centerline 22a of the main passage 22, which is along the main flow direction of the gas 2 being measured flowing in the main passage 22. That is, the protruding direction of the physical quantity detection device 100 in the main passage 22 is, for example, a direction orthogonal to the centerline 22a of the main passage 22.

[0037] A throttle valve 25 is, for example, built into a throttle body 23 located upstream of the intake manifold 24 in the direction of gas flow 2 being measured. A control device 4, for example, controls the flow rate of intake air into the combustion chamber of the cylinder 11 of the internal combustion engine 10 by changing the opening of the throttle valve 25 based on the amount of accelerator pedal operation. A throttle valve angle sensor 26 measures the opening of the throttle valve 25 and outputs the result to the control device 4. An idle air control valve 27 controls the amount of air bypassing the throttle valve 25.

[0038] The internal combustion engine 10 includes, for example, a cylinder 11, a piston 12, a spark plug 13, a fuel injection valve 14, an intake valve 15, an exhaust valve 16, and a rotation angle sensor 17. Intake air, drawn in through the air filter 21 based on the movement of the piston 12 of the internal combustion engine 10, flows in the main passage 22, and its flow rate is controlled by the throttle valve 25 in the throttle body 23. The intake air passing through the throttle body 23 passes through the intake manifold 24, then through the fuel injection valve 14 located at the intake port, and flows into the combustion chamber within the cylinder 11 via the intake valve 15.

[0039] The control device 4 controls the fuel injection valve 14 to inject fuel into the intake air based on the physical quantity input from the physical quantity detection device 100, which is the gas being measured 2. Thus, the intake air after passing through the intake manifold 24 mixes with the fuel injected from the fuel injection valve 14, and is guided to the combustion chamber as a gas-fuel mixture. The control device 4 ignites the mixture in the combustion chamber by spark ignition from the spark plug 13, causing explosive combustion and generating mechanical energy in the internal combustion engine 10.

[0040] Rotation angle sensor 17 detects information about the position and state of piston 12, intake valve 15, and exhaust valve 16, as well as the rotational speed of internal combustion engine 10, and outputs it to control device 4. Gases produced by combustion are discharged from the combustion chamber of cylinder 11 through exhaust valve 16 to the exhaust pipe, and are discharged outside the vehicle as exhaust gas 3. Oxygen sensor 28 is installed in the exhaust pipe, measures the oxygen concentration of the exhaust gas 3 flowing in the exhaust pipe, and outputs it to control device 4.

[0041] The control device 4 controls various parts of the internal combustion engine control system 1 based on physical quantities of the intake air (gas 2 being measured) flowing in the main passage 22, such as flow rate, temperature, humidity, and pressure, detected by the physical quantity detection device 100. Specifically, the control device 4 controls the flow rate of the intake air (gas 2 being measured) flowing in the main passage 22 based on the change in the opening of the throttle valve 25 when the accelerator pedal is operated. For example, the control device 4 controls the amount of fuel supplied from the fuel injection valve 14 based on the flow rate of the gas 2 being measured detected by the physical quantity detection device 100. This controls the mechanical energy generated by the internal combustion engine 10.

[0042] The control device 4 calculates the fuel injection quantity and ignition timing based on the output of the physical quantity detection device 100 (i.e., the physical quantity of intake air) and the rotational speed of the internal combustion engine 10 measured based on the output of the rotation angle sensor 17. Based on these calculation results, the control device 4 controls the fuel injection quantity of the fuel injection valve 14 and the ignition timing of the spark plug 13.

[0043] The control device 4 also precisely controls the fuel supply and ignition timing based on the temperature of the measured gas 2, the change in the opening of the throttle valve 25, the change in the rotational speed of the internal combustion engine 10, and the air-fuel ratio of the exhaust gas 3. Furthermore, when the internal combustion engine 10 is idling, the control device 4 controls the amount of air passing through the bypass throttle valve 25 using the idle air control valve 27, thereby controlling the rotational speed of the internal combustion engine 10 during idle operation.

[0044] The fuel supply and ignition timing, which are the main control quantities of the internal combustion engine 10, are calculated using the output of the physical quantity detection device 100 as the primary parameters. Therefore, improving the detection accuracy, suppressing time-varying changes, and enhancing the reliability of the physical quantity detection device 100 are crucial for improving the control accuracy and ensuring the reliability of the vehicle.

[0045] In recent years, in particular, there have been very high requirements for fuel efficiency in vehicles and for exhaust gas purification. To meet these requirements, it is crucial to improve the accuracy of the physical quantities of intake air detected by the physical quantity detection device 100. Furthermore, maintaining high reliability of the physical quantity detection device 100 is also important.

[0046] Vehicles equipped with physical quantity detection device 100 are used in environments with significant temperature and humidity variations. Preferably, the physical quantity detection device 100 is also designed to handle temperature and humidity variations in its operating environment, as well as dust, pollutants, and the like.

[0047] Furthermore, the physical quantity detection device 100 is installed in the intake manifold, which is affected by heat from the internal combustion engine. Therefore, the heat from the internal combustion engine is transferred to the physical quantity detection device 100 via the intake manifold. The physical quantity detection device 100 detects the flow rate of the gas 2 being measured by heat transfer with the gas being measured, so it is important to suppress external thermal influences as much as possible.

[0048] The following is for reference. Figures 2 to 8 The physical quantity detection device 100 of this embodiment will be described in more detail. Furthermore, in these figures, the physical quantity detection device 100 composed of [missing information] and [missing information] is shown. Figure 1 The main passage 22 shown is formed by an orthogonal coordinate system consisting of an X-axis parallel to the protruding direction of the physical quantity detection device 100, a Y-axis parallel to the center line 22a of the main passage 22, and a Z-axis parallel to the thickness direction of the physical quantity detection device 100. Furthermore, in the following description, it is assumed that the gas 2 being measured flows along the center line 22a (Y-axis) of the main passage 22.

[0049] Figure 2 yes Figure 1 Front view of the physical quantity detection device 100. Figure 3 It means Figure 2 A front view of the physical quantity detection device 100 after removing the liner 111c and the injection molded part 110a. Figure 4 , Figure 5 and Figure 6 They are Figure 1 The back view, left side view and right side view of the physical quantity detection device 100. Figure 7 It is along Figure 2 Cross-sectional view of the physical quantity detection device 100 for line VII-VII. Figure 8 It is along Figure 2 A longitudinal cross-sectional view of the physical quantity detection device 100 for lines VIII-VIII. Additionally, Figure 4 The image on the back shows the removal Figure 5 and Figure 6 The state of the physical quantity detection device 100 behind the cover 120.

[0050] The housing 110 is manufactured, for example, by injection molding of a synthetic resin material, and is disposed in the main passage 22 through which the measured gas 2 flows. The cover 120 is, for example, a plate-shaped component made of metal or synthetic resin. The cover 120 is, for example, a molded article made of synthetic resin material. The housing 110 and the cover 120 constitute the frame of the physical quantity detection device 100. The housing 110, for example, has a flange 111, a connector 112, and a measuring part 113.

[0051] Flange 111 Figure 7 As shown, the plate has a generally rectangular shape and a pair of fixing parts 111a at the corners of its diagonal. Each fixing part 111a has a through flange 111 at its center, through which a cylindrical through hole 111b is formed for inserting a threaded fixing member. To fix the physical quantity measuring device 100 to the main passage 22, the measuring part 113 is inserted into a mounting hole provided in the main passage 22. Then, the threaded fixing member inserted into the through hole 111b of the flange 111 is screwed into a threaded hole in the main passage 22, fixing the flange 111 to the passage wall of the main passage 22. Thus, the physical quantity measuring device 100 is fixed to the main passage 22, which serves as the gas inlet.

[0052] Connector 112 protrudes from flange 111 and is positioned outside the main gas inlet passage 22 for connection to external devices. For example... Figure 6 As shown, multiple external terminals 112a and correction terminals 112b are provided inside the connector 112. The external terminals 112a include, for example, output terminals for physical quantities such as flow rate and temperature, which are the measurement results of the physical quantity detection device 100, and power supply terminals for supplying DC power to operate the physical quantity detection device 100.

[0053] The correction terminal 112b is used to measure physical quantities after the physical quantity detection device 100 is manufactured, to determine the respective correction values ​​for the physical quantity detection device 100, and to store the correction values ​​in the internal memory of the physical quantity detection device 100. In subsequent physical quantity measurements performed by the physical quantity detection device 100, the correction data based on the correction values ​​stored in the aforementioned memory is used, and the correction terminal 112b is not used.

[0054] The measuring section 113 extends from the flange 111 fixed to the passage wall of the main passage 22 toward the centerline 22a of the main passage 22, protruding radially inward toward the main passage 22 which is orthogonal to the centerline 22a. The measuring section 113 has a flattened square shape that is approximately cuboid in shape. The measuring section 113 has a length in the protruding direction (X-axis direction) of the measuring section 113 in the main passage 22, and a width in the main flow direction (Y-axis direction) of the gas 2 being measured in the main passage 22. In addition, the measuring section 113 has a thickness in the direction orthogonal to the protruding direction (X-axis direction) and the main flow direction (Y-axis direction) of the gas 2 being measured (Z-axis direction). In this way, the measuring section 113 has a flattened shape along the main flow direction of the gas 2 being measured, thereby reducing the fluid resistance to the gas 2 being measured.

[0055] The measuring unit 113 has a front surface 113a, a back surface 113b, an upstream side surface 113c, a downstream side surface 113d, and a bottom surface 113e. The front surface 113a and back surface 113b have a larger area compared to the other surfaces of the measuring unit 113, and are approximately parallel to the protruding direction (X-axis direction) of the measuring unit 113 and the centerline 22a (Y-axis direction) of the main passage 22. The upstream side surface 113c and the downstream side surface 113d have an elongated shape with a smaller area compared to the front surface 113a and back surface 113b, and are approximately orthogonal to the centerline 22a (Y-axis direction) of the main passage 22. The bottom surface 113e has a smaller area compared to the other surfaces of the measuring unit 113, is approximately parallel to the centerline 22a (Y-axis direction) of the main passage 22, and is approximately orthogonal to the protruding direction (X-axis direction) of the measuring unit 113.

[0056] The measuring unit 113 has a secondary passage inlet 114 on its upstream side 113c and a first outlet 115 and a second outlet 116 on its downstream side 113d. The secondary passage inlet 114, the first outlet 115, and the second outlet 116 are located at the front end of the measuring unit 113, closer to the center than the center, in the protruding direction (X-axis direction). This allows the gas 2 to be measured near the center of the main passage 22, which is away from the inner wall of the main passage 22, to be introduced through the secondary passage inlet 114. Therefore, the physical quantity detection device 100 can suppress the decrease in measurement accuracy caused by the thermal effects of the internal combustion engine 10.

[0057] Figure 6 The external terminal 112a of the connector 112 shown is, for example, as Figure 3 As shown, it is connected to the pads of the circuit board 140 via bonding wire 143. The circuit board 140 has a protection circuit 144 mounted on its back side 140b, for example, where it is connected to the bonding wire 143. The protection circuit 144 stabilizes the voltage within the circuit and removes noise. The bonding wire 143 and the protection circuit 144 are as follows... Figure 8As shown, it is covered and sealed by the injection molded part 110a.

[0058] Injection molded part 110a is injection molded (injection molded) in circuit chamber 118 to seal the back side 140b of circuit board 140. As injection molded part 110a, for example, epoxy sealing material with higher rigidity compared to silicone gel and silicone-based sealing materials can be used. The coefficient of linear expansion of injection molded part 110a is preferably the same as that of housing 110, but in reality they are not the same and are different.

[0059] More specifically, when the raw material of injection molded part 110a is epoxy resin, the coefficient of linear expansion of injection molded part 110a is, for example, about 4.5

[10] -5 / K] to about 6.5[10 -5 / K] degree. On the other hand, when the raw material of the shell 110 is an engineering plastic such as polybutylene terephthalate (PBT), the coefficient of linear expansion of the shell 110 is, for example, about 6.0 [×10] -5 / K] to approximately 9.5[×10 -5 / K] degree. That is, the coefficient of linear expansion of the injection molded part 110a may be smaller than that of the shell 110, for example.

[0060] Casing 110 Figure 4 As shown, on the back side 113b of the measuring unit 113, there is a concave secondary passage groove 117 and a concave circuit chamber 118. (As shown...) Figure 8 As shown, the opening of the secondary passage 117 is closed by the cover 120, thereby forming a secondary passage 130 together with the cover 120. The secondary passage 130 is disposed in the housing 110, introducing a portion of the gas 2 to be measured from the main passage 22 and making it meander. The gas 2 to be measured flowing in the main passage 22 is, for example, as... Figure 4 and Figure 5 As shown, the sub-passage is introduced into the sub-passage 130 through the sub-passage inlet 114, which opens on the side 113c upstream of the measuring unit 113.

[0061] Sub-channel slot 117, for example Figure 4 As shown, it has a first secondary passageway 117a and a second secondary passageway 117b. The first secondary passageway 117a extends along the centerline 22a (Y-axis direction) of the main passageway 22 from a secondary passageway inlet 114 opening on the side 113c upstream of the measuring unit 113 to a first outlet 115 opening on the side 113d downstream of the measuring unit 113. The first secondary passageway 117a is, for example, as shown in the diagram. Figure 8 As shown, a first secondary passage 131 is formed between the main passage 120 and the shroud 120. The first secondary passage 131 allows the gas 2 to be measured, which is introduced from the secondary passage inlet 114, to return to the main passage 22 from the first outlet 115.

[0062] The second auxiliary passageway 117b is as follows Figure 4 As shown, the first secondary passageway 117a branches midway and extends towards the flange 111 along the protruding direction (X-axis direction) of the measuring section 113. Furthermore, the second secondary passageway 117b bends in a U-shape in the opposite direction and extends towards the front end of the measuring section 113 along the protruding direction (X-axis direction). The second secondary passageway 117b bends at the front end of the measuring section 113 in a direction along the centerline 22a (Y-axis direction) of the main passageway 22, and connects to the second outlet 116, which opens on the side 113d downstream of the measuring section 113. For example, as... Figure 7 As shown, in the second secondary passage groove 117b, the opening is closed by the cover 120, thereby forming a second secondary passage 132 between the secondary passage 117b and the cover 120. The secondary passage 130 includes a first secondary passage 131 and a second secondary passage 132.

[0063] The circuit chamber 118 is recessed on the base end side of the measuring section 113, which is connected to the flange 111, on the front side 113a and the back side 113b of the measuring section 113. The circuit chamber 118 is positioned adjacent to the upstream side of the second secondary passage groove 117b in the main flow direction (Y-axis direction) of the measured gas 2 flowing in the main passage 22, at a position closer to the base end side of the measuring section 113 than the first secondary passage groove 117a of the secondary passage groove 117.

[0064] Circuit Room 118 Figure 3 and Figure 8 As shown, the circuit board 140 is housed by the inner wall surface 119 of a housing 110 that surrounds at least a portion of the circuit board 140. On the front side 113a of the measuring section 113, the inner wall surface 119 of the housing 110 surrounds a portion of the circuit board 140 in such a way that a portion of the back side 140b of the circuit board 140 is exposed. On the other hand, on the back side 113b of the measuring section 113, the inner wall surface 119 of the housing 110 surrounds the entire circuit board 140 in such a way that the front side 140a of the circuit board 140 is substantially entirely exposed.

[0065] The inner wall surface 119 of the housing 110 is as follows Figure 2 and Figure 3 As shown, it includes a planar portion 119a and a non-planar portion 119b. The planar portion 119a is a portion of the inner wall surface 119 of the housing 110 that extends linearly when viewed from the thickness direction (Z direction) of the housing 110 of the physical quantity detection device 100. The non-planar portion 119b is a portion of the inner wall surface 119 of the housing 110 that is not linear when viewed from the thickness direction (Z direction) of the housing 110 of the physical quantity detection device 100. The non-planar portion 119b of the inner wall surface 119 of the housing 110 is, for example, a curved or arc-shaped portion connecting the planar portions 119a to each other.

[0066] The housing 110 has a stress-relieving wall 119c that forms at least a portion of a non-planar portion 119b included in the inner wall surface 119 of the defining circuit chamber 118. Figure 2 and Figure 3 In the example shown, the stress relief wall 119c is provided along the entirety of the non-planar portions 119b at both ends of the planar portion 119a located at the base end of the measuring portion 113 connected to the flange 111, which is one of the multiple non-planar portions 119b included in the inner wall surface 119 that divides the circuit chamber 118.

[0067] The stress-relieving wall 119c has a thickness T that allows it to elastically deform in response to the difference in thermal expansion between the injection molded part 110a and the housing 110. This thickness T can be calculated, for example, based on the amount of thermal expansion of the injection molded part 110a and the housing 110, and the Young's modulus of the raw material of the housing 110. Regarding the thickness T of the stress-relieving wall 119c, from the viewpoint of facilitating elastic deformation of the stress-relieving wall 119c, it is preferable to make it as thin as possible within the range where the housing 110 can be molded. More specifically, Figure 3 In the example shown, the thickness T of the stress-relieving wall 119c can be set as a lower limit of 0.8 mm to 1.0 mm and an upper limit of 1.5 mm to 2.0 mm.

[0068] The housing 110 has a stress relief groove 119d disposed on the outside of the circuit chamber 118 along at least a portion of a non-planar portion 119b that divides the inner wall surface 119 of the circuit chamber 118. Figure 7 and Figure 8 In the example shown, the depth D1 from the front 113a of the measuring section 113, where the opening of the stress relief groove 119d is formed, to the bottom of the stress relief groove 119d, is shallower than the depth D2 of the circuit chamber 118 from the same side of the housing 110 to the back 140b of the circuit board 140. However, the depth D1 of the stress relief groove 119d may also be deeper than the depth D2 of the circuit chamber 118.

[0069] Additionally, a stress-relieving wall 119c may be formed, for example, between the inner wall surface 119 that divides the circuit chamber 118 and the secondary passage 130. More specifically, it may be as follows: Figure 4 As shown, a stress-relieving wall 119c extending to the back side 140b of the circuit board 140 is formed between the wall of the second secondary passage groove 117 in the secondary passage groove 117 that forms the secondary passage 130 and the inner wall 119 of the circuit chamber 118.

[0070] like Figure 3 As shown, stress relief wall 119c is formed, for example, between the inner wall surface 119 that divides the circuit chamber 118 and the stress relief groove 119d. Figure 2 and Figure 3In the example shown, the inner wall surface 119 of the housing 110 that divides the circuit chamber 118 includes a planar portion 119a provided at the base end of the measuring portion 113, which is fixed to the passage wall of the main passage 22. The planar portion 119a at the base end of the measuring portion 113 extends, for example, in the width direction (Y-axis direction) of the measuring portion 113 of the housing 110. The stress relief groove 119d is provided at least along a non-planar portion 119b that is continuous with the planar portion 119a at the base end of the measuring portion 113.

[0071] Additionally, the measuring section 113 of the housing 110, as Figure 3 As shown, the measuring unit 113 has a flat plate shape with its width in the direction of the centerline 22a (Y-axis direction) of the main passage 22. In the measuring unit 113, the portion closer to the flange 111 of the passage wall of the main passage 22 has an inner wall surface 119 on one side of the circuit chamber 118 in the width direction (Y-axis direction) located further inside the width direction. Therefore, in the measuring unit 113, the portion closer to the flange 111 of the passage wall of the main passage 22 has a thickness increasing from the side surface 113c on one side of the measuring unit 113 in the width direction (Y-axis direction) to the stress relief groove 119d.

[0072] Additionally, the housing 110 has, for example, a plurality of stress relief grooves 119d provided along the inner wall surface 119 that divides the circuit chamber 118, and reinforcing ribs 119e formed between adjacent stress relief grooves 119d.

[0073] Chip package 150 Figure 4 , Figure 7 and Figure 8 As shown, the device has a base end portion 150b disposed in circuit chamber 118 with a connection terminal 153, and a front end portion 150a disposed in a second secondary passage 132 of secondary passage 130 with a flow sensor. The chip package 150, for example, utilizes transfer injection molding of a thermosetting resin to package the flow sensor (not shown) and... Figure 8 The electronic component 152 shown is integrally sealed. The chip package 150 utilizes, for example, the electronic component 152 to drive a flow sensor.

[0074] Electronic component 152, such as an LSI, is connected to the flow sensor via lead frame 154 to drive the flow sensor. The flow sensor is, for example, a thermal flow sensor. Figure 7 As shown, the bottom surface of a recess in the front end 150a of the chip package 150 is exposed, and the flow rate of the gas 2 being measured is measured in a measurement passage 132a formed between the recess and the extension 145 of the circuit board 140. The measurement passage 132a is, for example, as shown... Figure 4 and Figure 7As shown, it is formed in the second secondary passage groove 117b of the secondary passage groove 117, that is, in the second secondary passage 132 of the secondary passage 130.

[0075] like Figure 8 As shown, the connection terminal 153 of the chip package 150 is mounted on the circuit board 140. The connection terminal 153 is connected to the electronic component 152, for example, via a lead frame 154. The connection terminal 153 is mounted to the circuit board 140, for example, via a solder joint or other bonding agent. The connection terminal 153 is as follows... Figure 4 As shown, it is sealed by a curable sealant 141. For example, a silicone-based sealing material can be used as the curable sealant 141.

[0076] Additionally, on circuit board 140, besides the chip package 150 with the flow sensor, for example, such as Figure 4 As shown, at least one of a temperature sensor 160, a pressure sensor 170, and a humidity sensor 180 is also installed. The flow sensor, temperature sensor 160, pressure sensor 170, and humidity sensor 180 are sensor units that detect the physical quantity of the gas 2 being measured, which is introduced into the secondary passage 130 of the physical quantity detection device 100.

[0077] The sensor section of the physical quantity detection device 100, which includes the flow sensor, temperature sensor 160, pressure sensor 170, and humidity sensor 180, is mounted on the front side 140a of the circuit board 140, thereby mounting it on the circuit board 140. Furthermore, the circuit board 140 does not necessarily need to have all the sensor sections of the temperature sensor 160, pressure sensor 170, and humidity sensor 180, except for the flow sensor; any one of these sensor sections can be omitted.

[0078] Temperature sensor 160 is, for example, a chip-type temperature sensor mounted on circuit board 140. Temperature sensor 160 is, for example, a chip-type temperature sensor. Figure 4 and Figure 5 As shown, the front end of the extension 142 of the circuit board 140, which extends towards the front end of the measuring unit 113 in the protruding direction (X-axis direction), is disposed. The temperature sensor 160 is disposed in the temperature measuring passage 190 of the measuring unit 113 and measures the temperature of the gas 2 being measured, which is introduced into the temperature measuring passage 190 from the main passage 22.

[0079] Thermometer measuring circuit 190 Figure 5 As shown, an inlet is provided on the side 113c of the upstream side of the measuring unit 113, such as... Figure 2 and Figure 4As shown, the measuring unit 113 has outlets on both its front side 113a and back side 113b. The temperature measuring passage 190 introduces the gas 2 being measured, which flows in the main passage 22, through an inlet opening in the side 113c on the upstream side of the measuring unit 113, and discharges it into the main passage 22 through the outlets opening in the front side 113a and back side 113b of the measuring unit 113. By adopting this structure, the heat dissipation of the temperature sensor 160 can be improved.

[0080] Pressure sensor 170, for example Figure 4 As shown, it is mounted on the front side 140a of the circuit board 140 and disposed within the circuit chamber 118. The circuit chamber 118 communicates with the foldback portion of the second secondary passage groove 117b, which is U-shaped near the flange 111, namely the foldback portion of the second secondary passage 132. Thus, the pressure of the gas 2 to be measured, which is introduced into the secondary passage 130, can be measured using the pressure sensor 170 disposed in the circuit chamber 118.

[0081] Humidity sensor 180, for example Figure 4 As shown, the sensor 180 is mounted on the front side 140a of the circuit board 140, and is positioned in a defined area on the front end side of the measuring section 113 compared to the circuit chamber 118. This defined area is, for example, connected to a second sub-passage 132 of the sub-passage 130. Thus, the humidity sensor 180 detects the humidity of the gas 2 being measured, which is introduced into the sub-passage 130.

[0082] The function of the physical quantity detection device 100 in this embodiment will be explained below.

[0083] The physical quantity detection device 100 of this embodiment, as described above, includes a housing 110, a secondary passage 130, a sensor unit, a circuit board 140, a circuit chamber 118, and an injection molded part 110a. The housing 110 is disposed in the main passage 22 through which the gas to be measured 2 flows. The secondary passage 130 is disposed in the housing 110, and a portion of the gas to be measured 2 is introduced from the main passage 22. The sensor unit detects the physical quantity of the gas to be measured 2 introduced into the secondary passage 130. The sensor unit is mounted on the surface 140a of the circuit board 140. The circuit chamber 118 is defined by the inner wall surface 119 of the housing 110, which surrounds at least a portion of the circuit board 140, and houses the circuit board 140. The injection molded part 110a is injection molded in the circuit chamber 118 to seal the back side 140b of the circuit board 140. The housing 110 has a stress-relieving wall 119c constituting at least a portion of the non-planar portion 119b included in the inner wall surface 119 defining the circuit chamber 118. The stress-relieving wall 119c has a thickness T that allows it to elastically deform in response to the thermal expansion difference between the injection molded part 110a and the housing 110.

[0084] By adopting this structure, the physical quantity detection device 100 of this embodiment is installed in the main passage 22, which is part of the intake passage of the internal combustion engine 10. It can introduce part of the intake air, which is the gas to be measured 2, flowing in the main passage 22 after being introduced into the intake passage via the air filter 21, into the secondary passage 130 of the housing 110. Furthermore, the physical quantity detection device 100 can use sensor units such as flow sensor 150, temperature sensor 160, pressure sensor 170, or humidity sensor 180 in chip package 150 to detect physical quantities such as flow rate, temperature, pressure, or humidity of the gas to be measured 2 introduced into the secondary passage 130, and output them to the control device 4. In addition, the injection molded part 110a is injection molded in the circuit chamber 118 that houses the circuit board 140, sealing the front side 140a and the opposite back side 140b of the circuit board 140 on which the sensor unit is installed, thereby preventing corrosion of the components installed on the circuit board 140 and the intrusion of water droplets into the circuit chamber 118.

[0085] Furthermore, in the physical quantity detection device 100, when the temperature of the housing 110 and the injection molded part 110a rises or falls, the thermal stress generated by the difference in thermal expansion between the housing 110 and the injection molded part 110a tends to concentrate on a portion of the injection molded part 110a adjacent to the non-planar portion 119b of the inner wall surface 119 of the defining circuit chamber 118. However, in the physical quantity detection device 100 of this embodiment, the stress-relieving wall 119c constituting at least a portion of the non-planar portion 119b of the inner wall surface 119 of the defining circuit chamber 118 has a thickness T that allows it to elastically deform in accordance with the difference in thermal expansion between the injection molded part 110a and the housing 110. Therefore, when the temperature of the housing 110 and the injection molded part 110a rises or falls, the stress relief wall 119c elastically deforms following the difference in thermal expansion between the injection molded part 110a and the housing 110, suppressing the thermal stress concentration on a portion of the injection molded part 110a adjacent to the non-planar portion 119b, thereby improving the reliability of the injection molded part 110a.

[0086] Furthermore, in the physical quantity detection device 100 of this embodiment, the housing 110 has a stress relief groove 119d provided on the outside of the circuit chamber 118 along at least a portion of a non-planar portion 119b of the inner wall surface 119 defining the circuit chamber 118. A stress relief wall 119c is formed between the inner wall surface 119 defining the circuit chamber 118 and the stress relief groove 119d.

[0087] By adopting such a structure, the position, thickness, height, and length of the stress-relieving wall 119c can be easily adjusted by adjusting the position, width, depth, and length of the stress-relieving groove 119d formed on the outer side of the inner wall surface 119 constituting the circuit chamber 118. Furthermore, by forming the stress-relieving groove 119d in the housing 110, not only can the housing 110 be made lighter and the amount of material used reduced, but also the recesses, depressions, and shrinkage marks caused by molding shrinkage can be suppressed.

[0088] Furthermore, in the physical quantity detection device 100 of this embodiment, the housing 110 has a measuring portion 113 that is fixed to the passage wall of the main passage 22 and protrudes radially inward into the main passage 22. The inner wall surface 119 of the defining circuit chamber 118 of the housing 110 includes a planar portion 119a provided at the base end of the measuring portion 113 fixed to the main passage 22. Furthermore, the stress relief groove 119d is provided at least along a non-planar portion 119b that is continuous with the planar portion 119a provided at the base end of the measuring portion 113.

[0089] By adopting this structure, the physical quantity detection device 100 of this embodiment can form a stress-relieving wall 119c at the base end of the measuring section 113 along the non-planar portions 119b on both sides of the planar portion 119a. In the physical quantity detection device 100, the base end of the measuring section 113, which is fixed to the passage wall of the main passage 22, is a fixed end, and the front end of the measuring section 113, located radially inward of the main passage 22, is a free end. Therefore, the stress acting on the measuring section 113 due to the vibration of the housing 110 is higher at the base end of the measuring section 113 than at the front end. However, by utilizing the stress-relieving wall 119c at the base end of the measuring section 113, stress concentration on a portion of the injection molded part 110a adjacent to the non-planar portion 119b at the base end of the measuring section 113 can be suppressed, thereby improving the reliability of the injection molded part 110a.

[0090] Furthermore, in the physical quantity detection device 100 of this embodiment, the measuring section 113 of the housing 110 has a flat plate shape with the width direction (Y-axis direction) in the direction of the center line 22a of the main passage 22. Additionally, the measuring section 113... Figure 3 As shown, the closer the portion is to the flange 111 side of the passage wall of the main passage 22, the more the inner wall surface 119 of the circuit chamber 118 in the specified width direction (Y-axis direction) is located in the width direction, thereby increasing the thickness from the side of the measuring section 113 in the width direction to the stress relief groove 119d.

[0091] By adopting such a structure, the rigidity of the measuring section 113 can be improved at the base end of the measuring section 113 where the stress acting on the measuring section 113 due to the vibration of the housing 110 is relatively high. As a result, the stress acting on the base end of the measuring section 113 due to the vibration of the housing 110 can be reduced, thereby improving the reliability of the physical quantity detection device 100 in the face of vibration of the housing 110.

[0092] Furthermore, in the physical quantity detection device 100 of this embodiment, the housing 110 has a plurality of stress-relieving grooves 119d provided along the inner wall surface 119 of the circuit chamber 118, and reinforcing ribs 119e formed between adjacent stress-relieving grooves 119d. By adopting such a structure, the housing 110 is reinforced with reinforcing ribs 119e, which can suppress the reduction in rigidity of the housing 110 caused by the formation of stress-relieving grooves 119d, thereby improving the reliability of the physical quantity detection device 100.

[0093] Furthermore, in the physical quantity detection device 100 of this embodiment, Figure 7 and Figure 8 The depth D1 shown, from one side of the housing 110 with the opening forming the stress relief groove 119d to the bottom of the stress relief groove 119d, can be deeper than the depth D2 of the circuit chamber 118 from one side of the housing 110 to the back side 140b of the circuit board 140.

[0094] By adopting this structure, the stress-relieving wall 119c formed between the inner wall surface 119 of the circuit chamber 118 and the stress-relieving groove 119d more easily follows the difference in thermal expansion between the housing 110 and the injection molded part 110a, resulting in elastic deformation. Therefore, it is possible to more effectively suppress thermal stress concentration on a portion of the injection molded part 110a adjacent to the non-planar portion 119b of the inner wall surface 119 of the circuit chamber 118, further improving the reliability of the physical quantity detection device 100.

[0095] Furthermore, in the physical quantity detection device 100 of this embodiment, a stress-relieving wall 119c can be formed between the inner wall surface 119 of the circuit chamber 118 and the secondary passage 130. By adopting such a structure, the secondary passage 130 of the housing 110 can be used as a stress-relieving groove 119d, reducing the thermal stress generated in the injection molded part 110a due to the thermal expansion difference between the housing 110 and the injection molded part 110a, thereby improving the reliability of the physical quantity detection device 100.

[0096] As explained above, according to this embodiment, a physical quantity detection device 100 can be provided that can alleviate thermal stress acting on the injection-molded part 110a being injection-molded into the housing 110 and improve reliability. However, the physical quantity detection device of the present invention is not limited to the structure of the physical quantity detection device 100 of the above embodiment. Hereinafter, reference will be made to... Figures 9 to 17The following describes variations 1 to 9 of the physical quantity detection device 100 of the above embodiments.

[0097] Figure 9 This is a front view showing a modified example 1 of the physical quantity detection device 100 according to the above embodiment. Additionally, Figure 9 The physical quantity detection device 100 corresponding to the above embodiment Figure 3 This illustrates the state in which the circuit board 140 is subsequently removed. In the physical quantity detection device 100 of this modified example 1, the stress relief wall 119c and the stress relief groove 119d are continuously arranged to surround the circuit chamber 118 from three directions, which is consistent with... Figure 3 The physical quantity detection device 100 shown in the above embodiment is different.

[0098] More specifically, Figure 9 In the physical quantity detection device 100 of the modified example 1 shown, the stress-relieving wall 119c and the stress-relieving groove 119d surround the circuit chamber 118 of the housing 110 from the following three directions. The first direction is the upstream side (negative Y-axis direction side) when the measured gas 2 flows downstream. The second direction is the base end side (radial outer side of the main passage 22) in the protruding direction (X-axis direction) of the measuring part 113 of the housing 110. The third direction is the downstream side (positive Y-axis direction side) when the measured gas 2 flows downstream.

[0099] A portion of the stress-relieving wall 119c and stress-relieving groove 119d surrounding the circuit chamber 118 in the first direction extends continuously along the inner wall surface 119 of the circuit chamber 118 from the non-planar portion 119b on the front end side of the measuring section 113 to the non-planar portion 119b on the base end side of the measuring section 113. A portion of the stress-relieving wall 119c and stress-relieving groove 119d surrounding the circuit chamber 118 in the second direction extends continuously along the width direction of the measuring section 113 from one end of the circuit chamber 118 in the width direction (Y-axis direction) to the other end. A portion of the stress-relieving wall 119c and stress-relieving groove 119d surrounding the circuit chamber 118 in the third direction extends from the non-planar portion 119b of the circuit chamber 118 located on the base end side of the measuring section 113 to the non-planar portion 119b adjacent to the folded-back portion of the second secondary passage 132 in the protruding direction (X-axis direction) of the measuring section 113.

[0100] According to the physical quantity detection device 100 of this modified example, the same effect as that of the physical quantity detection device 100 of the above embodiment can be achieved. In addition, by continuously arranging the stress-relieving wall 119c and the stress-relieving groove 119d to surround the circuit chamber 118 from the above three directions, the physical quantity detection device 100 of this modified example can more effectively relieve the thermal stress caused by the difference in thermal expansion between the housing 110 and the injection molded part 110a.

[0101] Furthermore, in the physical quantity detection device 100 of this modified example, the stress relief groove 119d can have two or more different depths D1 in the circumferential direction of the inner wall surface 119 surrounding the circuit board 140. By adopting such a structure, the ease of elastic deformation of the stress relief wall 119c can be adjusted according to the position of the inner wall surface 119 in the circumferential direction, and thermal stress concentration on the injection molded part 110a can be prevented more effectively.

[0102] Figure 10 This is a front view showing a modified example 2 of the physical quantity detection device 100 according to the above-described embodiment. In this modified example of the physical quantity detection device 100, the stress relief groove 119d surrounding the circuit chamber 118 from three directions is divided by a plurality of reinforcing ribs 119e, which is consistent with... Figure 9 The physical quantity detection device 100 shown in Modified Example 1 is different. According to the physical quantity detection device 100 of this Modified Example, in addition to having the same effect as the physical quantity detection device 100 of Modified Example 1, the housing 110 can be strengthened with multiple reinforcing ribs 119e, suppressing the reduction in rigidity of the housing 110 caused by the formation of stress relief grooves 119d, and improving the reliability of the physical quantity detection device 100.

[0103] Figure 11 This is a front view of a modified example 3 of the physical quantity detection device 100 according to the above embodiment. In this modified example of the physical quantity detection device 100, the stress relief groove 119d, which is provided closest to the downstream side (positive Y-axis direction side) of the gas 2 being measured and closest to the base end side (negative X-axis direction side) of the measuring unit 113, extends towards the front end side of the measuring unit 113. Figure 3 The physical quantity detection device 100 shown in the above embodiment is different.

[0104] In the physical quantity detection device 100 of this modified example, the stress relief groove 119d is connected to the recess 119f of the housing 110 and extends in the direction of the centerline 22a of the main passage 22, that is, in the width direction (Y-axis direction) of the measuring section 113. The depth D1 of the stress relief groove 119d can be different from the depth of the recess 119f. By adopting such a structure, the stress relief wall 119c formed between the stress relief groove 119d and the inner wall surface 119 of the circuit chamber 118 can be extended in the protruding direction (X-axis direction) of the measuring section 113, which can more effectively relieve the thermal stress generated in the injection molded part 110a.

[0105] Figure 12This is a front view of a fourth modification of the physical quantity detection device 100 according to the above-described embodiment. In this modification, the portion of the inner wall 119 of the circuit chamber 118 located on the base end side (negative X-axis direction side) of the measuring section 113 relative to the second secondary passage 132 is entirely an arc-shaped non-planar portion 119b, unlike the physical quantity detection device 100 of the above-described embodiment. This modification of the physical quantity detection device 100 achieves the same effects as the physical quantity detection device 100 of the above-described embodiment.

[0106] In addition, such as Figure 12 When the shape of the circuit chamber 118 shown is, for example, circular, elliptical, or other closed curves, the inner wall surface 119 defining the circuit chamber 118 may only include non-planar portions 119b. Alternatively, when the shape of the circuit chamber 118 is, for example, triangular, quadrilateral, or other polygonal, the inner wall surface 119 defining the circuit chamber 118 may include multiple planar portions 119a, and the non-planar portions 119b may be the corners between adjacent planar portions 119a. In such cases, the same effect as the physical quantity detection device 100 of the above embodiment can be achieved.

[0107] Figure 13 This is a front view of a modified example 5 of the physical quantity detection device 100 according to the above-described embodiment. In this modified example, at least a portion of the stress relief groove 119d is filled with a filler material 110b that is the same material as the injection molded part 110a, which is consistent with... Figure 10 The physical quantity detection device 100 shown in Modification 2 is different. More specifically, in the physical quantity detection device 100 of this modification, the two stress relief grooves 119d formed at both ends of the non-planar portions 119b of the planar portion 119a closest to the base end side (negative X-axis direction side) of the inner wall surface 119 of the circuit chamber 118 are filled with filling material 110b.

[0108] By adopting this structure, the filler material 110b, which is filled in the stress-relieving groove 119d through the stress-relieving wall 119c in the portion of the injection molded part 110a adjacent to the non-planar portions 119b at both ends of the aforementioned planar portion 119a, expands thermally in the same way as the injection molded part 110a. As a result, the thermal stress acting on the portion of the injection molded part 110a adjacent to the non-planar portions 119b at both ends of the aforementioned planar portion 119a is relieved, and the reliability of the physical quantity detection device 100 is improved.

[0109] Figure 14This is a front view of a modified example 6 of the physical quantity detection device 100 according to the above embodiment. In this modified example, the inner wall surface 119 defining the circuit chamber 118 has a protrusion 119g, which differs from the physical quantity detection device 100 of the above embodiment. The protrusion 119g is provided at both ends of the non-planar portion 119b closest to the base end side (negative X-axis direction side) of the planar portion 119a in relation to the inner wall surface 119 of the circuit chamber 118, and adjacent to the front end side (positive X-axis direction side) of the planar portion 119a.

[0110] The protrusion 119g is located at the end of the planar portion 119a adjacent to the non-planar portion 119b, and protrudes perpendicularly outward from the circuit chamber 118 relative to the planar portion 119a. With this structure, thermal stress tends to concentrate in the vicinity of the protrusion 119g on the injection molded part 110a. As a result, the thermal stress concentration on the portion of the injection molded part 110a adjacent to the non-planar portion 119b is mitigated, improving the reliability of the physical quantity detection device 100.

[0111] Figure 15 This is a front view of a modified example 7 of the physical quantity detection device 100 according to the above embodiment. In this modified example, the inner wall surface 119 defining the circuit chamber 118 has a recess 119h, which differs from the physical quantity detection device 100 of the above embodiment. The recess 119h is a portion of the inner wall surface 119 of the circuit chamber 118 that is arc-shaped and recessed inwards from the circuit chamber 118.

[0112] Figure 15 In the example shown, multiple recesses 119h are spaced apart circumferentially on the inner wall surface 119. With this structure, thermal stress tends to concentrate on the injection molded part 110a near each recess 119h. As a result, the overall thermal stress concentration on the injection molded part 110a is mitigated, improving the reliability of the physical quantity detection device 100.

[0113] Figure 16 This is an enlarged cross-sectional view of a modified example 8 of the physical quantity detection device 100 according to the above-described embodiment. In the physical quantity detection device 100 of the above-described embodiment and modifications 1 to 7, the stress relief groove 119d is provided in the measuring section 113, but in this modified example of the physical quantity detection device 100, the stress relief groove 119d is provided in the flange 111. The stress relief groove 119d has a depth in the protruding direction (X-axis direction) of the secondary passage 130. According to this modified example of the physical quantity detection device 100, the same effect as the physical quantity detection device 100 of the above-described embodiment can be achieved.

[0114] Figure 17This is an enlarged cross-sectional view of a modified example 9 of the physical quantity detection device 100 according to the above embodiment. Similar to the physical quantity detection device 100 of the above embodiment, in this modified example, the housing 110 has a flange 111 fixed to the passage wall of the main passage 22, and a measuring portion 113 connected to the flange 111 and protruding radially inward into the main passage 22. Furthermore, in this modified example, a circuit chamber 118 is provided on the flange 111. This modified example of the physical quantity detection device 100 can also achieve the same effects as the physical quantity detection device 100 of the above embodiment.

[0115] The embodiments and variations of the physical quantity detection device of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to the above embodiments and variations. Even design changes that do not depart from the spirit of the present invention are included in the present invention.

[0116] Explanation of reference numerals in the attached figures

[0117] 2. Gas being measured

[0118] 22 Main Pathway

[0119] 22a Centerline

[0120] 100 Physical Quantity Detection Device

[0121] 110 housing

[0122] 110a injection molded parts

[0123] 110b filler material

[0124] 111 Flange

[0125] 113 Measurement Department

[0126] 118 Circuit Room

[0127] 119 inner wall

[0128] 119a Planar Section

[0129] 119b Non-planar part

[0130] 119c stress-relieving wall

[0131] 119d stress relief groove

[0132] 119e reinforced ribs

[0133] 130 Secondary Pathway

[0134] 150 chip package (sensor section)

[0135] 160 Temperature Sensor (Sensor Section)

[0136] 170 Pressure Sensor (Sensor Section)

[0137] 180° humidity sensor (sensor section)

[0138] 140 circuit board

[0139] 140a front

[0140] 140b back

[0141] D1 Depth

[0142] D2 Depth

[0143] T represents thickness.

Claims

1. A physical quantity detection device, characterized in that, include: The housing is located in the main passageway for the flow of the gas being measured; A secondary passage is provided in the housing to draw a portion of the gas to be measured from the main passage; The sensor unit detects the physical quantity of the gas being measured that is taken into the sub-channel; The circuit board of the sensor unit is mounted on the front; A circuit chamber, defined by the inner wall of the housing surrounding at least a portion of the circuit board, is used to house the circuit board. and An injection-molded part, which is injected into the circuit chamber to seal the back of the circuit board. In the physical quantity detection device The housing has a stress-relieving wall that forms at least a portion of the non-planar portion included in the inner wall surface defining the circuit chamber. The stress-relieving wall has a thickness capable of elastically deforming in response to the difference in thermal expansion between the injection molded part and the housing. The housing has a stress-relieving groove disposed on the outer side of the circuit chamber along at least a portion of the non-planar portion defining the inner wall surface of the circuit chamber. The stress-relieving wall is formed between the inner wall surface defining the circuit chamber and the stress-relieving groove. The housing has a plurality of stress-relieving grooves disposed along the inner wall surface defining the circuit chamber; and reinforcing ribs formed between adjacent stress relief grooves of the plurality of stress relief grooves.

2. The physical quantity detection device as described in claim 1, characterized in that: The housing has a measuring part that is fixed to the passage wall of the main passage and protrudes radially inward into the main passage. The inner wall surface defining the circuit chamber includes a planar portion provided at the base end of the measuring unit, which is fixed to the passage wall. The stress relief groove is provided at least along the non-planar portion that is continuous with the planar portion.

3. The physical quantity detection device as described in claim 2, characterized in that: The measuring part of the housing has a flat plate shape with the width direction of the centerline of the main passage as the width direction. In the measuring unit, the portion closer to the passage wall of the main passage, the inner wall surface of the circuit chamber on one side in the width direction is located more on the inner side in the width direction, thereby increasing the thickness from one side of the measuring unit in the width direction to the stress relief groove.

4. The physical quantity detection device as described in claim 1, characterized in that: The stress relief groove has two or more different depths in the circumferential direction surrounding the inner wall surface of the circuit board.

5. The physical quantity detection device as described in claim 1, characterized in that: The depth from one side of the housing with the opening forming the stress relief groove to the bottom of the stress relief groove is greater than the depth from one side of the housing to the circuit chamber on the back side of the circuit board.

6. The physical quantity detection device as described in claim 1, characterized in that: The stress-relieving wall is formed between the inner wall surface defining the circuit chamber and the secondary passage.

7. The physical quantity detection device as described in claim 1, characterized in that: The housing has: a flange fixed to the passage wall of the main passage; and a measuring part connected to the flange and protruding radially inward into the main passage. The circuit chamber is disposed on the flange.

8. The physical quantity detection device as described in claim 1, characterized in that: The inner wall surface defining the circuit chamber includes only the non-planar portion.

9. The physical quantity detection device as described in claim 1, characterized in that: The inner wall surface defining the circuit chamber includes a plurality of planar portions. The non-planar portion is the corner between adjacent planar portions of the plurality of planar portions.

10. The physical quantity detection device as described in claim 1, characterized in that: At least a portion of the stress relief groove is filled with a filler material that is the same as the material of the injection molded part.

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