Physical quantity detection device

Abstract

The objective of this invention is to provide a physical quantity detection device capable of suppressing the influence of sound pressure resonance on flow characteristics. The physical quantity detection device of this invention includes: a housing disposed in a main passage; a secondary passage formed in the housing; a flow detection unit disposed in the secondary passage; a circuit unit electrically connected to the flow detection unit; a circuit chamber formed in the housing to house the circuit unit; and a first inlet passage, one end of which opens in the secondary passage and the other end of which opens in the circuit chamber, connecting the secondary passage and the circuit chamber. The flow detection unit has a diaphragm, the front side of which is exposed in the secondary passage, and the back side of which is exposed in a closed chamber communicating with the circuit chamber. The circuit chamber has at least one protrusion disposed at a position opposite to the opening at the other end of the first inlet passage.

Description

Technical Field

[0001] This invention relates to a physical quantity detection device, for example, for detecting the physical quantity of intake air in an internal combustion engine. Background Technology

[0002] Patent Document 1 illustrates the structure of an airflow measuring device, which internally comprises: a bypass flow path for acquiring a portion of air flowing in a main flow path formed within a duct; and a secondary bypass flow path for acquiring a portion of air branching from and flowing within the bypass flow path, wherein a sensor is disposed in the secondary bypass flow path. The sensor has a diaphragm for detecting flow rate, and the front of the diaphragm element is exposed from the secondary bypass flow path, while the back of the diaphragm element is exposed from a closed chamber communicating with a circuit chamber via an air exchange port.

[0003] Existing technical documents

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-34508 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Even when mounted on various internal combustion engines, physical quantity sensing devices are required to accurately measure flow signals. In recent years, it has been known that the sound pressure generated by the turbocharger downstream of the physical quantity sensing device mounted on the internal combustion engine affects the flow characteristics of the device. The resonance phenomenon of sound pressure on the front and back sides of the diaphragm element caused by the turbocharger affects the flow characteristics, thus generating flow measurement errors. In the existing structures described above, i.e., those where the vent of the physical quantity sensing device is only connected to the secondary or main passage by a connecting path, there exists a problem of flow measurement errors caused by sound pressure.

[0008] The present invention was made in view of the above-mentioned problems, and its object is to provide a physical quantity detection device that can suppress the influence of sound pressure resonance on flow characteristics.

[0009] Methods for solving problems

[0010] The physical quantity detection device of the present invention solves the above-mentioned technical problems.

[0011] It is a physical quantity detection device that detects the physical quantity of the gas being measured flowing in the main channel.

[0012] It includes: a housing disposed in the main passage; a secondary passage formed in the housing; a flow detection unit disposed in the secondary passage; a circuit unit electrically connected to the flow detection unit; a circuit chamber formed in the housing to house the circuit unit; and a first pressure introduction passage, one end of which opens in the secondary passage and the other end of which opens in the circuit chamber, connecting the secondary passage and the circuit chamber, and enabling the pressure of the gas to be measured to be introduced from the secondary passage into the circuit chamber.

[0013] The flow detection unit includes: a diaphragm, the front of which is exposed in the secondary passage and the back of which is exposed in a closed chamber isolated from the secondary passage; and a second pressure introduction passage, one end of which is open in the circuit chamber and the other end of which is open in the closed chamber, connecting the circuit chamber and the closed chamber, and enabling the introduction of the pressure of the gas to be measured from the circuit chamber to the closed chamber.

[0014] The circuit chamber has at least one protrusion located opposite the opening at the other end of the first pressure inlet passage.

[0015] Invention Effects

[0016] According to the present invention, a physical quantity detection device is provided that can suppress the influence of sound pressure resonance on flow characteristics.

[0017] Further features relating to the present invention will become clear from the description and accompanying drawings. Furthermore, technical problems, structures, and effects other than those described above will become clear from the following description of embodiments. Attached Figure Description

[0018] Figure 1 This is a system diagram illustrating one embodiment of the physical quantity detection device of the present invention used in an internal combustion engine control system.

[0019] Figure 2 This is the front view of the physical quantity detection device.

[0020] Figure 3 This diagram shows the state of the device after the cover has been removed from its casing.

[0021] Figure 4 It is a three-dimensional view showing the back of the cover.

[0022] Figure 5 It is cut at the joint surface with the outer shell. Figure 2 A cross-sectional view of the cover.

[0023] Figure 6 yes Figure 5 VI-VI line cross-sectional diagram.

[0024] Figure 7 This is a cross-sectional view of a chip package.

[0025] Figure 8 yes Figure 5 Enlarged view of the main parts.

[0026] Figure 9 yes Figure 5 The cross-sectional view of line VIII-VIII.

[0027] Figure 10 yes Figure 9 Enlarged view of the main parts.

[0028] Figure 11 This is a graph illustrating the differences between the invented product and the comparative example.

[0029] Figure 12 This is a graph showing the sound pressure measurement results of the product of the present invention and the comparative example.

[0030] Figure 13 This is a diagram illustrating a variation of the first embodiment. Detailed Implementation

[0031] The embodiments described below (hereinafter referred to as "Examples") solve various technical problems required as actual products, and in particular, solve various desired technical problems for use as a detection device for detecting the physical quantity of intake air in a vehicle, thus achieving various effects. One of the various technical problems solved by the following embodiments is described in the "Technical Problem to be Solved by the Invention" section, and another is one of the various effects achieved by the following embodiments, described in the "Invention Effects" section. The various technical problems solved by the following embodiments, and the various effects achieved through the following embodiments, are described in the description of the embodiments. Therefore, for the technical problems solved and the effects achieved by the embodiments described below, content other than that in the "Technical Problem to be Solved by the Invention" section and the "Invention Effects" section is also described.

[0032] In the following embodiments, even if the numbers are different, the same reference numerals indicate the same structure and achieve the same effect. Regarding the structures already described, sometimes only reference numerals are used in the figures without further explanation.

[0033] <First Embodiment>

[0034] Figure 1 This is a system diagram illustrating an embodiment of the physical quantity detection device of the present invention used in an internal combustion engine system 1 with electronic fuel injection.

[0035] The physical quantity detection device of this embodiment is used in an internal combustion engine system 1 of an automobile. The internal combustion engine system 1 has an engine 2 with a turbocharger 15. In the main passage 22, from the upstream side, a filter 4, a physical quantity detection device 20, an intercooler 6, a throttle valve 7, and an intake pipe 8 are arranged in sequence. An exhaust catalyst 10 is arranged in the exhaust passage 9. A thermal humidity measuring device 11, an intake pressure sensor 12, and an intake temperature sensor 13 are installed on the intake pipe 8 to measure the humidity, pressure, and temperature of the intake air drawn into the engine 2.

[0036] The physical quantity detection device 20 detects physical quantities such as flow rate, temperature, humidity, and pressure of the intake air (the gas to be measured) obtained from the air filter 4 and flowing in the main passage 22. The physical quantities detected by the physical quantity detection device 20 are converted into electrical signals and input to the control unit (ECU). The control unit uses the physical quantities of the intake air, which are the output of the physical quantity detection device 20, to calculate the fuel injection quantity and ignition timing of the engine 2.

[0037] Figure 2 This is the front view of the physical quantity detection device.

[0038] The physical quantity detection device 20 is used in a state where it is inserted into the main passage 22 through a mounting hole provided in the passage wall of the main passage 22 and fixed to the main passage 22. The physical quantity detection device 20 includes a housing disposed on the main passage 22 where the gas flow to be measured is flowing. The housing of the physical quantity detection device 20 has an outer shell 100 and a cover 200 mounted on the outer shell 100. The outer shell 100 is formed, for example, by injection molding of a synthetic resin material. The cover 200 is composed of a plate-like component, which is made of, for example, a metal material or a synthetic resin material; in this embodiment, it is made of an injection-molded aluminum alloy or a synthetic resin material.

[0039] The housing 100 has: a flange 111 for fixing the physical quantity detection device 20 to the main passage 22; a connector 112 that protrudes from the gas intake to the outside for electrical connection with an external device; and a measuring section 113 that extends from the flange 111 toward the center of the main passage 22.

[0040] The measuring section 113 is formed into a thin and long shape extending straight from the flange 111, having a wide front side 121, a back side 122, and a pair of narrow side sides 123 and 124. With the physical quantity detection device 20 mounted on the main passage 22, the measuring section 113 protrudes from the inner wall of the main passage 22 toward the center of the passage 22. The front side 121 and back side 122 are arranged parallel to the central axis of the main passage 22. Of the narrow side sides 123 and 124 of the measuring section 113, the side 123 on the long side is positioned opposite the upstream side of the main passage 22, and the side 124 on the short side is positioned opposite the downstream side of the main passage 22. With the physical quantity detection device 20 mounted on the main passage 22, the front end of the measuring section 113 is used as the lower surface 125.

[0041] The measuring unit 113 has a secondary passage inlet 131 on side 123 and a first outlet 132 and a second outlet 133 on side 124. The secondary passage inlet 131, the first outlet 132, and the second outlet 133 are located at the front end of the measuring unit 113, which extends from the flange 111 toward the center of the main passage 22. The physical quantity detection device 20 is formed such that the measuring unit 113 extends in a direction orthogonal to the centerline of the main passage 22, but the widths of the sides 123 and 124 are narrow. As a result, the physical quantity detection device 20 can control the fluid resistance to a small value for the gas being measured.

[0042] Figure 3 This diagram shows the state after the cover has been removed from the outer casing of the physical quantity detection device. Figure 4 This is the back view of the lid. Figure 5 It is cut at the joint surface with the outer shell. Figure 2 A cross-sectional view of the cover. Furthermore, in the following description, the direction in which the measuring section 113 extends from the flange 111, i.e., the length direction of the measuring section 113, is sometimes referred to as the Z-axis; the direction in which the measuring section 113 extends from the secondary passage inlet 131 to the first outlet 132, i.e., the short side direction of the measuring section 113, is sometimes referred to as the X-axis; and the direction in which the measuring section 113 extends from the front side 121 to the back side 122, i.e., the thickness direction of the measuring section 113, is sometimes referred to as the Y-axis.

[0043] A flow sensor 411, an intake temperature sensor 321, and a humidity sensor 322, serving as flow detection elements, are provided in the measuring section 113 of the housing 100. The flow sensor 411 is positioned midway through the secondary passage 134. The flow sensor 411 detects the flow rate of the gas being measured flowing through the main passage. The intake temperature sensor 321 is positioned midway through the temperature detection passage 136, one end of which opens near the secondary passage inlet 131 on the side 123, and the other end opens on both the front 121 and the back of the measuring section 113. The intake temperature sensor 321 detects the temperature of the gas being measured flowing in the main passage. The humidity sensor 322 is positioned in the humidity measuring chamber 137 of the measuring section 113. The humidity sensor 322 measures the humidity of the gas being measured, which is introduced into the humidity measuring chamber 137 through a window 138 opening on the back of the measuring section 113.

[0044] A secondary passage 134 and a circuit chamber 135 for housing the circuit board 300 are provided on the measuring section 113. The circuit chamber 135 and the secondary passage 134 form a structure that is covered and closed by a cover 200 installed on the front side 121 of the measuring section 113.

[0045] The cover 200 has a flat plate shape that covers the front surface 121 of the measuring section 113. For example... Figure 4 As shown, the cover 200 has a rib 221 on its back side. The rib 221 is formed along the adhesive portion to the measuring part 113. Figure 5 As shown, a groove 141 is provided on the front side 121 of the measuring section 113, into which the rib 221 is inserted. With the rib 221 inserted into the groove 141 of the measuring section 113, the cover 200 is bonded with adhesive.

[0046] The circuit chamber 135 is located in the main passage 22 on the X-axis side (side 123 side), which is upstream of the flow direction of the gas being measured. The secondary passage 134 is located in the region closer to the front end of the measuring unit 113 in the Z-axis direction (lower surface 125 side) than the circuit chamber 135, and in the region closer to the downstream side of the flow direction of the gas being measured in the main passage 22 (side 124 side) than the circuit chamber 135.

[0047] The secondary passage 134 has a first secondary passage A and a second secondary passage B, which branches off midway from the first secondary passage A. The first secondary passage A has a structure extending along the X-axis direction of the measuring section 113 between a secondary passage inlet 131 opening on one side 123 of the measuring section 113 and a first outlet 132 opening on the other side 124 of the measuring section 113. The first secondary passage A has a flow path extending from the secondary passage inlet 131 along the flow direction of the measured gas in the main passage 22 and connecting to the first outlet 132. The first secondary passage A can introduce the measured gas flowing in the main passage 22 from the secondary passage inlet 131 and return the introduced measured gas from the first outlet 132 to the main passage 22. The first secondary passage A is formed by a first secondary passage groove recessed into the front surface of the measuring section 113 by the region 201 of the cover 200.

[0048] The second auxiliary passage B branches off midway from the first auxiliary passage A and bends towards the base end (flange side) of the measuring section 113, extending along the Z-axis direction of the measuring section 113. It bends towards the other side (side 124 side) of the measuring section 113 in the X-axis direction at the base end of the measuring section 113, and then U-bends towards the front end of the measuring section 113, again extending along the Z-axis direction of the measuring section 113. It has a structure that bends towards the other side (side 124 side) of the measuring section 113 in the X-axis direction ahead of the first outlet 132, and is continuous with the second outlet 133 which opens into the side 124 of the measuring section 113. The second outlet 133 is positioned opposite to the downstream side of the flow direction of the measured gas in the main passage 22. The second outlet 133 has an opening area approximately the same as or slightly larger than the first outlet 132, and is formed at a position closer to the base end of the measuring section 113 in the longitudinal direction than the first outlet 132.

[0049] The second auxiliary passage B has a reciprocating flow path along the Z-axis direction of the measuring section 113. The second auxiliary passage B has: a forward passage B1 that branches off midway from the first auxiliary passage A and extends towards the base end of the measuring section 113 (away from the first auxiliary passage A); and a return passage B2 that bends U-shaped at the base end of the measuring section 113 (away from the end of the passage) and extends towards the front end of the measuring section 113 (approaching the first auxiliary passage A). The return passage B2 has a flow path connected to a second outlet 133 that opens towards the downstream side of the flow direction of the measured gas within the main passage 22, closer to the auxiliary passage inlet 131. The second auxiliary passage B allows the measured gas flowing in from the branch of the first auxiliary passage A to pass through and return to the main passage 22 from the second outlet 133. The second auxiliary passage B is formed by a second auxiliary passage groove 152 recessed into the front surface of the measuring section 113 by the area 202 of the cover 200.

[0050] A first inlet passage 161, capable of introducing the pressure of the gas to be measured from the second auxiliary passage B into the circuit chamber 135, is provided midway through the passage. One end of the first inlet passage 161 opens into the second auxiliary passage B, and the other end opens into the circuit chamber 135, connecting the second auxiliary passage B and the circuit chamber 135. The first inlet passage 161 has an inlet port 162 opening into the second auxiliary passage B. The inlet port 162 is positioned offset outward from the side wall of the second auxiliary passage B.

[0051] The inlet 162 of the second auxiliary passage B is disposed on the side wall of the outer periphery, which is bent into a semi-circular arc shape, in the return section where the passage returns from the outgoing passage B1 to the return passage B2, and is located in the curved portion closer to the return passage B2 than the top of the return section. The first inlet passage 161 has the following shape: it extends from the inlet 162 along the Z-axis direction of the measuring section 113 toward the base end of the measuring section 113, bends into a generally L-shape toward the side 123 of the measuring section 113 and extends along the X-axis direction, and is continuous with the opening 163 that opens in the circuit chamber 135.

[0052] A flow sensor (flow detection unit) 411 is disposed midway between the second auxiliary passage B and the passage section B1. The inlet 162 is located downstream of the flow sensor 411 in the direction of gas flow in the second auxiliary passage B. The flow sensor 411 is mounted on a sensor assembly 400, which is mounted on a circuit board 300.

[0053] The circuit board 300 has a sensor assembly 400, a pressure sensor 320, an intake temperature sensor 321, and a humidity sensor 322 mounted on its front mounting surface, and a chip resistor or chip capacitor (not shown) mounted on its rear mounting surface. The circuit board 300 is arranged within the measuring section 113 such that its length extends from the base end to the front end of the measuring section 113, and its short side extends from the side 123 to the side 124 of the measuring section 113.

[0054] The circuit board 300 has a substrate body 301 disposed within a circuit chamber 135, and is provided with a first protrusion 302 disposed in a temperature detection passage 136, a second protrusion 303 disposed in a humidity measurement chamber 137, and a third protrusion 304 disposed in a destination passage portion B1 of the second sub-passage B, extending flush with the substrate body 301. An intake temperature sensor 321 is mounted on the front end of the first protrusion 302, and a humidity sensor 322 is mounted on the second protrusion 303. The third protrusion 304 is disposed opposite to the sensor assembly 400 in the destination passage portion B1 of the second sub-passage B. The third protrusion 304 of the circuit board 300 closes the open portion of the recess 404 of the sensor assembly 400 to form a first passage portion D1. Furthermore, the third protrusion 304 of the circuit board 300 forms a second passage portion D2 between itself and the bottom wall surface 152a of the second sub-passage groove 152.

[0055] In the sensor assembly 400, the base end of the support 401 is fixed to the circuit board 300 within the circuit chamber 135, and the front end protrudes into the second secondary passage groove 152, where a flow sensor 411 is mounted. The flow sensor 411 is supported on the sensor assembly 400 such that it protrudes from the destination passage portion B1 of the second secondary passage B. The flow sensor 411 is positioned relative to the circuit board 300 protruding from the circuit chamber 135 at a predetermined interval, and measures the flow rate of the gas to be measured passing through the second secondary passage B.

[0056] Figure 7 yes Figure 6 An enlarged view of the sensor assembly 400 shown.

[0057] The sensor assembly 400 has a structure in which a flow sensor 411, an LSI 412, and a lead frame 413 are molded from resin into a resin encapsulation. The flow sensor 411 and the LSI 412 are mounted on one surface of the lead frame 413. The sensor assembly 400 is formed by sealing the flow sensor 411 with resin to expose the diaphragm of the flow sensor 411.

[0058] The sensor assembly 400 has a support body 401 with a flat plate shape and a specified thickness, formed from molding resin. The base end 401A of the support body 401 is disposed within a circuit chamber 135, and the front end 401B of the support body 401 protrudes and is disposed in a second secondary passage groove 152. The sensor assembly 400 is electrically connected to and mechanically fixed to the circuit board 300 via a fixing part.

[0059] A groove 404 is formed at the front end of the support 401. The groove 404 is formed at the front end of the support 401 in such a way that it extends in the width direction of the front end of the support 401, and the flow sensor 411 is exposed at the middle position of the extension direction. The flow sensor 411 has a sensor element 405 with a diaphragm structure. The sensor element 405 of the flow sensor 411 has a diaphragm, the front side 411a of which is exposed from the passage portion B1 of the second sub-passage B, and the back side 411b of which is exposed from the closed chamber 421 isolated from the sub-passage 134.

[0060] A heater section is disposed on the front side 411a of the diaphragm, and a pair of resistor sections are disposed at positions separated from each other by the heater section. Air passing through the front side 411a of the diaphragm is heated by the heater section, and the heat distribution changes according to the air flow. The flow sensor 411 measures the flow rate of the gas being measured based on the change in resistance based on the change in heat distribution.

[0061] A closed chamber 421 is disposed in the sensor element 405 of the flow sensor 411. The sensor element 405 is mounted on one side of the lead frame 413, and the closed chamber 421 is sealed by polyimide tape 414 attached to the other side of the lead frame 413, forming a closed space isolated from the outside.

[0062] A ventilation passage 422 is provided in the sensor assembly 400, with one end opening in the circuit chamber 135 and the other end opening in the closed chamber 421, connecting the circuit chamber 135 and the closed chamber 421. A continuous groove is formed on the other side of the lead frame 413 between the opening 423 and the closed chamber 421. A sheet of polyimide tape 414 is adhered to the other side of the lead frame 413 to block the open portion of the groove, forming a ventilation passage 422 with one end opening in the closed chamber 421 and the other end continuous with the opening 423. The ventilation passage 422 connects the closed chamber 421 exposed on the back side 411b of the diaphragm and the circuit chamber 135. The ventilation passage 422 constitutes a second inlet passage capable of introducing the pressure of the measured gas from the circuit chamber 135 into the closed chamber 421.

[0063] Figure 8 yes Figure 5 Enlarged view of the main parts Figure 9 yes Figure 5 Sectional view of line VIII-VIII, Figure 10 yes Figure 9 Enlarged view of the main parts.

[0064] In the circuit chamber 135, at least one protrusion 210 is provided at a position opposite to the opening 163 of the first inlet passage 161. The protrusion 210 is formed by a plurality of concave and convex shapes. The protrusion 210 is integrally formed with the cover 200. The protrusion 210 forms a predetermined gap between itself and the side wall of the circuit chamber 135 and between itself and the circuit board 300, so that the gas to be measured can move between the second sub-passage B and the circuit chamber 135 through the first inlet passage 161.

[0065] For example, Figure 4 and Figure 9 As shown, the protrusion 210 has a first protrusion 211 and a second protrusion 212. The first protrusion 211 is positioned within the circuit chamber 135 opposite to the opening 163 of the first inlet passage 161, and the second protrusion 212 is positioned separated from the opening 163 of the first inlet passage 161 via the first protrusion 211. The first protrusion 211 has a cuboid shape with a length W1 approximately the same as the opening width W0 of the opening 163, and is positioned opposite to the first protrusion 211 across the entire width W0 of the opening 163. The second protrusion 212 has a cuboid shape with a length W2 longer than the opening width W0 of the opening 163, and is arranged parallel to the first protrusion 211.

[0066] like Figure 10 As shown, the protrusion 210 forms a space S1 between the front end of the first protrusion 211 and the substrate body 301 of the circuit board 300, a space S2 between the first protrusion 211 and the second protrusion 212, and a space S3 between the front end of the second protrusion 212 and the substrate body 301 of the circuit board 300. Spaces S1 and S2 have the following relationship: space S1 is narrower (smaller cross-sectional area) on the side closer to the opening 163 of the first inlet passage 161, and space S2 is wider (larger cross-sectional area) on the side farther from the opening 163 of the first inlet passage 161 (S1 < S2). Furthermore, regarding spaces S2 and S3, space S3 is narrower than space S2.

[0067] Figure 11 It is a graph illustrating the differences between the invented product and the comparative example. Figure 11 (1) The structure of the comparative example that does not have the protrusion 210 is shown. Figure 11 (2) This shows the structure of the product of the present invention having the protrusion 210. Figure 11 (3) A graph showing the relationship between sound pressure and distance to the measurement point with and without the protrusion.

[0068] In this embodiment, the physical quantity detection device 20 is equipped with a turbocharger 15 downstream. The sound waves generated by the turbocharger enter the circuit chamber 135 from the second auxiliary passage B through the first inlet passage 161.

[0069] like Figure 11 (1) As shown in the comparative example, the sound wave SW entering the circuit chamber 135 from the opening 163 of the first inlet passage 161 enters the circuit chamber 135 without any obstruction, so its sound pressure hardly decreases as it enters the depth of the circuit chamber 135. It then passes through the ventilation passage 422 from the opening 423 of the sensor assembly 400 to the closed chamber 421 exposed on the back side of the diaphragm. As a result, resonance of sound pressure occurs on the front and back sides of the diaphragm element, and the temperature distribution of the heater section of the diaphragm changes due to thermal convection caused by the thermoacoustic effect, which may lead to flow rate detection errors.

[0070] On the other hand, such as Figure 11 As shown in (2), in the case of the present invention, the sound wave SW entering the circuit chamber 135 from the opening 163 of the first inlet passage 161 is blocked by the protrusion 210 and cannot travel straight, and the sound pressure diffraction of the sound wave SW is attenuated and reduced. For example, as Figure 11 As shown in (3), the sound pressure is smaller when there is a protrusion compared to when there is no protrusion.

[0071] Furthermore, if the sound wave SW entering the circuit chamber 135 from the opening 163 of the first inlet passage 161 travels from space S1 to space S2, and the cross-sectional area increases, its velocity and pressure decrease due to fluid expansion. Only the reduced energy passes through space S3, while the remaining energy is attenuated by reflection within space S2. Because the sound wave is reflected at locations where impedance changes rapidly (rapid expansion, rapid contraction), it is reflected at the entrance between spaces S2 and S1 and at the exit between spaces S2 and S3. Through this reflection, sound wave interference occurs in spaces S1, S2, and S3, the energy of the sound wave is consumed, and the sound pressure decreases.

[0072] Therefore, the sound pressure within the second sub-channel B can be actively attenuated, and the transmission of sound waves with high energy to the closed chamber 421 can be suppressed. Thus, sound pressure resonance can be prevented on the front and back sides of the diaphragm element, improving the accuracy of flow detection.

[0073] Figure 12 This is a graph showing the sound pressure measurement results of the product of the present invention and the comparative example.

[0074] It can be seen that the maximum sound pressure level difference near the specified frequency is 28 dB in the comparative example, while the maximum sound pressure level in the product of the present invention is 25 dB. Compared with the comparative example, the sound pressure level of the product of the present invention is reduced and thus improved.

[0075] Figure 13 It means and Figure 8 The corresponding figure is a modified example of this embodiment.

[0076] In a modified example, the protrusion 210 has a plurality of third protrusions 213. Each of the third protrusions 213 is rod-shaped and disposed within the circuit chamber 135 opposite to the opening 163 of the first inlet passage 161. The plurality of third protrusions 213 are arranged in a houndstooth (serrated; staggered) pattern, spaced apart at predetermined intervals, over a length approximately equal to the opening width W0 of the opening 163. The plurality of third protrusions 213 are arranged at intervals with a degree of obstruction, thereby preventing sound waves SW entering the circuit chamber 135 from the opening 163 of the first inlet passage 161 from traveling in a straight line.

[0077] According to the modified example, similar to the above embodiment, the sound pressure in the second sub-channel B can be actively attenuated, and the transmission of sound waves with high energy to the closed chamber 421 can be suppressed. Therefore, sound pressure resonance on the front and back sides of the diaphragm element can be prevented, improving the accuracy of flow detection. In addition, by changing the number of the third protrusions 213, the amount of sound pressure attenuation can be arbitrarily adjusted.

[0078] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments. Various design changes can be made without departing from the spirit of the invention as set forth in the claims. For example, the above-described embodiments are provided for ease of understanding of the present invention and are not limited to including all the structures described. Furthermore, a portion of the structure of one embodiment can be replaced with a structure of another embodiment, and a structure of another embodiment can be added to the structure of one embodiment. In addition, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0079] Explanation of reference numerals in the attached figures

[0080] 15: Turbocharger

[0081] 20: Physical quantity detection device

[0082] 100: Outer shell (casing)

[0083] 200: Cover (shell)

[0084] 134: Secondary Pathway

[0085] 135: Circuit Room

[0086] 161: First Importation Pathway

[0087] 162: Inlet

[0088] 163: Opening

[0089] 210: Protrusion

[0090] 211: First protrusion

[0091] 212: Second protrusion

[0092] 213: Third protrusion

[0093] 300: Circuit board (circuit section)

[0094] 400: Sensor assembly

[0095] 411: Flow sensor (flow detection unit)

[0096] 411a: Front side of the diaphragm

[0097] 411b: Back side of the diaphragm

[0098] 422: Ventilation passage

[0099] B: Secondary pathway

[0100] B1: Head to the passageway department

[0101] B2: Return to the passageway.

Claims

1. A physical quantity detection device for detecting the physical quantity of a measured gas flowing in a main passage, characterized in that, include: The housing disposed in the main passage; Secondary passages formed within the shell; Flow detection unit configured in this secondary pathway; The circuit section electrically connected to the flow detection unit; A circuit chamber formed in the housing for housing the circuit section; and The first inlet passage has one end open to the secondary passage and the other end open to the circuit chamber, connecting the secondary passage and the circuit chamber, allowing the pressure of the gas to be measured to be introduced from the secondary passage into the circuit chamber. The flow detection unit has: A diaphragm, the front side of which is exposed in the secondary passage, and the back side of which is exposed in a closed chamber isolated from the secondary passage; and The second inlet passage, with one end open in the circuit chamber and the other end open in the closed chamber, connects the circuit chamber and the closed chamber, enabling the pressure of the gas to be measured to be introduced from the circuit chamber to the closed chamber. The circuit chamber has at least one protrusion at a position opposite to the opening at the other end of the first inlet passage.

2. The physical quantity detection device as described in claim 1, characterized in that: The protrusion has a first protrusion positioned opposite the opening and a second protrusion positioned spaced apart from the opening by the first protrusion.

3. The physical quantity detection device as described in claim 2, characterized in that: The first protrusion has a length equal to the opening width of the opening, and is disposed opposite to the opening across its entire width. The second protrusion has a length longer than the opening width of the opening and is arranged parallel to the first protrusion.

4. The physical quantity detection device as described in claim 1, characterized in that: The protrusion has a plurality of third protrusions that are respectively formed in the shape of rods.

5. The physical quantity detection device as described in claim 4, characterized in that: The plurality of third protrusions are arranged in a houndstooth pattern, with a length range equal to the opening width of the opening, and spaced apart from each other at predetermined intervals.

6. The physical quantity detection device as described in claim 1, characterized in that: The first inlet passage is provided with an inlet at a position offset outward from the side wall of the secondary passage.

7. The physical quantity detection device as described in claim 6, characterized in that: The secondary passage has a going passage extending along a predetermined axial direction to one side, and a returning passage extending along the other axial direction by a U-shaped bend at the end of the going passage. The inlet is located on the side wall of the outer periphery of the secondary passage, which is bent into a semi-circular arc shape, and is closer to the return passage side than the top of the reverse passage.

8. The physical quantity detection device as described in claim 7, characterized in that: The secondary passage is provided with a flow detection unit for detecting the flow rate of the gas to be measured, and the inlet is located downstream of the flow detection unit in the flow direction of the gas to be measured in the secondary passage.

9. The physical quantity detection device as described in claim 8, characterized in that: The flow detection unit is located in the destination path of the secondary path.

Images