Flow measuring device

Abstract

The present application provides a flow measuring device capable of suppressing inclination of a chip package with respect to a circuit board and reducing deviation in flow detection accuracy. The flow measuring device (20) of the present application is characterized by comprising: a chip package (310) having a flow sensor (311) and formed with a passage wall (314); and a circuit board (300) on which the chip package (310) is mounted, the chip package (310) being arranged such that the flow sensor (311) opposes a portion of the circuit board (300), and a portion of the passage wall (314) as a resin portion of the chip package (310) is in contact with the circuit board (300) to be mounted.

Description

Technical Field

[0001] This invention relates to a flow measuring device for measuring the flow rate of a gas being measured. Background Technology

[0002] Patent document 1 describes the following: "A physical quantity measuring device for detecting the physical quantity of a gas to be measured flowing in a main passage, the physical quantity measuring device comprising: a flow sensor for detecting the flow rate of the gas to be measured; an LSI for driving the flow sensor; a chip package formed by sealing the flow sensor and a lead frame supporting the LSI with resin; and a circuit board for mounting the chip package, the chip package being fixed to the circuit board in a state in which a portion of the flow sensor protrudes laterally from an end of the circuit board."

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: WO2019 / 064887 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The flow measurement device in Patent Document 1 has the following structure: a connection terminal provided at the base end of a chip package is welded and fixed to a substrate; a groove formed at the top end of the chip package is disposed opposite to the substrate; and a flow sensor provided in the groove detects the flow rate of the gas to be measured flowing through the passage formed by the substrate and the groove. The chip package has a structure that cantileveredly supports itself on the substrate by welding, therefore the posture of the chip package during welding is prone to instability. Therefore, if the chip package is welded and fixed to the substrate in an orientation tilted relative to a reference, the size of the passage may change, potentially causing deviations in the flow measurement accuracy of each component.

[0008] The present invention was made in view of the above-mentioned problems, and its object is to provide a flow measurement device that can suppress the tilt of the chip package relative to the substrate and reduce the deviation of flow detection accuracy.

[0009] means for solving problems

[0010] The flow measurement device of the present invention, which solves the above-mentioned problems, is characterized by comprising: a resin encapsulation having a flow detection element and having a passage wall formed thereon; and a substrate on which the resin encapsulation is mounted, the resin encapsulation being configured such that the flow detection element is opposite to a portion of the circuit board, and a portion of the resin portion of the resin encapsulation is in contact with the circuit board for mounting.

[0011] Invention Effects

[0012] According to the present invention, tilting of the chip package relative to the substrate can be suppressed, reducing deviations in flow detection accuracy. Other features related to the present invention will become clear from the description and drawings in this specification. Furthermore, issues, structures, and effects other than those described above will become clear from the following description of embodiments. Attached Figure Description

[0013] Figure 1 This is a system diagram illustrating one embodiment of the flow measurement device of the present invention used in an internal combustion engine control system.

[0014] Figure 2 This is a front view of the flow measurement device according to the first embodiment.

[0015] Figure 3 This is a front view of the circuit board on which the chip package of the first embodiment is installed.

[0016] Figure 4 yes Figure 3 A schematic diagram of the AA-line section viewed from the side.

[0017] Figure 5 This is a diagram illustrating another variation, which is related to... Figure 4 The corresponding diagram.

[0018] Figure 6 This is a diagram illustrating another variation, which is related to... Figure 4 The corresponding diagram.

[0019] Figure 7 This is a diagram illustrating another variation, which is related to... Figure 4 The corresponding diagram.

[0020] Figure 8 This is a rear view of the chip package in the first embodiment.

[0021] Figure 9 This is a diagram illustrating another variation, which is related to... Figure 8 The corresponding diagram.

[0022] Figure 10 This is a diagram illustrating another variation, which is related to... Figure 8 The corresponding diagram.

[0023] Figure 11 This is a diagram illustrating another variation, which is related to... Figure 8 The corresponding diagram.

[0024] Figure 12 This is a front view of the circuit board on which the chip package of the second embodiment is installed, and is related to... Figure 3 The corresponding diagram.

[0025] Figure 13 This is a diagram illustrating a comparative example. Detailed Implementation

[0026] The embodiments described below for implementing the present invention solve various problems that are desirable to address as a practical product, particularly those desired for use as a detection device for detecting the physical quantities of intake air in a vehicle, and thus provide various effects. One of the various problems solved by the following embodiments is described in the "Problems to be Solved by the Invention" section, and another of the various effects provided by the following embodiments is described in the "Invention Effects" section. The various problems solved by the following embodiments, and the various effects provided by the following embodiments, are described in the following description of the embodiments. Therefore, the problems solved and effects of the embodiments described in the following embodiments also include content beyond that in the "Problems to be Solved by the Invention" and "Invention Effects" sections.

[0027] In the following embodiments, even if the drawing numbers are different, the same reference symbols represent the same structure and achieve the same effect. For structures that have already been described, only reference symbols are added in the drawings, and sometimes the description is omitted.

[0028] Figure 1 This is a system diagram illustrating an embodiment of the flow measurement device of the present invention used in an internal combustion engine control system 1 with electronic fuel injection. According to the operation of the internal combustion engine 10 having engine cylinders 11 and engine pistons 12, intake air, as the measured gas 2, is drawn in from the air filter 21 and introduced into the combustion chamber of the engine cylinder 11 via, for example, the intake manifold, throttle body 23, and intake manifold 24, which serve as the main passage 22. The physical quantity of the measured gas 2, which is the intake air introduced into the combustion chamber, is detected by the flow measurement device 20 of the present invention. Based on this detected physical quantity, fuel is supplied from the fuel injection valve 14 and introduced into the combustion chamber as a mixture with the measured gas 2. Furthermore, in this embodiment, the fuel injection valve 14 is provided at the intake port of the internal combustion engine. The fuel injected into the intake port forms a mixture with the measured gas 2 and is introduced into the combustion chamber via the intake valve 15, where it burns to generate mechanical energy.

[0029] The fuel and air introduced into the combustion chamber form a fuel-air mixture, which is ignited by the spark plug 13 and combusts explosively, generating mechanical energy. The combusted gases are introduced through the exhaust valve 16 into the exhaust pipe and discharged outside the vehicle as exhaust gas 3. The flow rate of the intake air (measuring gas 2) introduced into the combustion chamber is controlled by the throttle valve 25, whose opening varies according to the operation of the accelerator pedal. The fuel supply is controlled based on the flow rate of the intake air introduced into the combustion chamber. By controlling the opening of the throttle valve 25, the driver can control the flow rate of the intake air introduced into the combustion chamber, thereby controlling the mechanical energy generated by the internal combustion engine.

[0030] The flow rate measuring device 20 detects the flow rate, temperature, humidity, pressure, and other physical quantities of the intake air (gas 2 to be measured) drawn from the air filter 21 and flowing through the main passage 22. An electrical signal representing the physical quantities of the intake air is input from the flow rate measuring device 20 to the control device 4. Additionally, the output of the throttle angle sensor 26, which measures the opening of the throttle valve 25, is input to the control device 4. Furthermore, the output of the rotation angle sensor 17 is input to the control device 4 to measure the position and state of the engine piston 12, intake valve 15, exhaust valve 16, and the engine speed. The output of the oxygen sensor 28 is input to the control device 4 to measure the fuel-air mixture ratio based on the state of the exhaust gas 3.

[0031] The control unit 4 calculates the fuel injection quantity and ignition timing based on the physical quantity of intake air output from the flow measurement device 20 and the engine speed measured from the output of the rotation angle sensor 17. Based on these calculations, it controls the amount of fuel supplied from the fuel injection valve 14 and the ignition timing by the spark plug 13. The fuel supply quantity and ignition timing are also precisely controlled based on changes in temperature and throttle angle detected by the flow measurement device 20, changes in engine speed, and the air-fuel ratio measured by the oxygen sensor 28. Furthermore, in the idling state of the internal combustion engine, the control unit 4 controls the amount of air bypassing the throttle valve 25 via the idle air control valve 27, thereby controlling the engine speed in the idling state.

[0032] The fuel supply and ignition timing, which are the main control quantities of an internal combustion engine, are calculated using the output of the flow measurement device 20 as the primary parameters. Therefore, improving the detection accuracy of the flow measurement device 20, suppressing time-varying variations, and enhancing its reliability are crucial for improving the control accuracy and ensuring the reliability of the vehicle.

[0033] In recent years, in particular, there have been very high requirements for vehicle fuel efficiency and exhaust gas purification. To meet these requirements, it is extremely important to improve the detection accuracy of the physical quantities of intake air detected by the flow measurement device 20. Furthermore, maintaining the high reliability of the flow measurement device 20 is also crucial.

[0034] Vehicles equipped with flow measurement device 20 are used in environments with large variations in temperature and humidity. The flow measurement device 20 is preferably designed to cope with variations in temperature and humidity in its operating environment, as well as with dust and pollutants.

[0035] Furthermore, the flow measuring device 20 is installed on 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 flow measuring device 20 via the intake manifold. The flow measuring device 20 detects the flow rate of the gas being measured 2 by heat transfer with the gas being measured 2; therefore, it is important to suppress the influence of external heat as much as possible.

[0036] As described below, the flow measurement device 20 mounted on the vehicle not only solves the problems listed in the "Problems to be Solved by the Invention" section and achieves the effects listed in the "Effects of the Invention" section, but also, as described below, fully considers the aforementioned problems, solves the various problems sought to be solved as a product, and achieves various effects. The specific problems solved by the flow measurement device 20 and the specific effects achieved are described in the following description of the embodiments.

[0037] <First Implementation> Figure 2 This is a front view of the flow measuring device in the first embodiment, showing the state after the cover has been removed from the housing. Furthermore, in the following description, the gas being measured flows along the central axis 22a of the main passage 22.

[0038] The flow measuring device 20 is used in a state where it is inserted into the main passage 22 through a mounting hole provided on the passage wall and fixed to the main passage 22. The flow measuring device 20 has a frame disposed on the main passage 22 for the flow of the gas 2 to be measured. The frame of the flow measuring device 20 has a housing 100 and a cover (not shown) mounted on the front side of the housing 100. The housing 100 is constructed, for example, by injection molding of a synthetic resin material. Moreover, the cover is constructed by a plate-like component made of, for example, a metal material or a synthetic resin material; in this embodiment, it is constructed by injection molding of an aluminum alloy or a synthetic resin material. The cover has a size that covers the entire front side of the housing 100.

[0039] The housing 100 has a flange 111 for fixing the flow measuring device 20 to the air inlet pipe body, which serves as the main passage 22, a connector 112 that protrudes from the flange 111 and is exposed to the outside from the air inlet pipe body for electrical connection with external devices, and a measuring part 113 that extends protruding from the flange 111 toward the center of the main passage 22.

[0040] The measuring part 113 of the flow measuring device 20 is inserted into the main passage 22 through the mounting hole. The flange 111 of the flow measuring device 20 abuts against the main passage 22 and is fixed to the main passage 22 with screws.

[0041] The measuring section 113 is thin and long, extending straight from the flange 111, and has a wide front side 121 and a back side, as well as a pair of narrow side sides 123 and 124. When the flow measuring device 20 is installed 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. Moreover, the front side 121 and the back side are arranged parallel to the central axis of the main passage 22, and of the narrow side sides 123 and 124 of the measuring section 113, the side side 123 on the width direction of the measuring section 113 is arranged opposite to the upstream side of the main passage 22, and the side side 124 on the other side of the width direction of the measuring section 113 is arranged opposite to the downstream side of the main passage 22.

[0042] In this embodiment, with the flow measuring device 20 installed on the main passage 22, the base end of the measuring part 113 is positioned on the upper side, and the top end of the measuring part 113 is positioned on the lower side. However, the posture of using the flow measuring device 20 is not limited to this embodiment, and can be in various postures, such as a horizontally installed posture in which the base end and top end of the measuring part 113 are at the same height.

[0043] In the following description, the direction in which the measuring part 113 extends from the flange 111, i.e. the length direction of the measuring part 113, is sometimes referred to as the Z-axis; the direction in which the measuring part 113 extends from the secondary passage inlet 131 toward the first outlet 132, i.e. the width direction of the measuring part 113, is sometimes referred to as the X-axis; and the direction in which the measuring part 113 extends from the front side 121 toward the back side 122, i.e. the thickness direction of the measuring part 113, is sometimes referred to as the Y-axis.

[0044] 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 top end of the measuring unit 113, which extends from the flange 111 toward the center of the main passage 22. Therefore, gas from the portion near the center of the inner wall surface away from the main passage 22 can be drawn into the secondary passage 134. Thus, the flow measuring device 20 can measure the flow rate of gas from the portion away from the inner wall surface of the main passage 22, and can suppress the decrease in measurement accuracy caused by the influence of heat, etc.

[0045] The measuring section 113 of the flow measuring device 20 is shaped to extend long along the axis from the outer wall of the main passage 22 toward the center, but the width of the sides 123 and 124 is narrow. As a result, the flow measuring device 20 can suppress the fluid resistance of the gas 2 being measured to a small value.

[0046] The measuring section 113 of the flow measuring device 20 is equipped with a flow sensor 311, an inlet air temperature sensor 321, and a humidity sensor 322 as flow detection elements. The flow sensor 311 has a diaphragm structure and is disposed midway through the secondary passage 134. The flow sensor 311 detects the flow rate of the gas 2 being measured flowing through the main passage. The inlet air temperature sensor 321 is disposed 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 inlet air temperature sensor 321 detects the temperature of the gas 2 being measured flowing through the main passage. The humidity sensor 322 is disposed in the humidity measuring chamber 137 of the measuring section 113. The humidity sensor 322 measures the humidity of the gas 2 being measured, which is taken into the humidity measuring chamber 137 through a window 138 opening on the back of the measuring section 113.

[0047] The housing 100 is provided with a sub-passage groove 150 for forming a sub-passage 134 and a circuit chamber 135 for accommodating the circuit board 300. The circuit chamber 135 and the sub-passage groove 150 are recessed in the front of the measuring section 113 and are covered by a cover (not shown) installed on the front of the measuring section 113. The circuit chamber 135 is located in the main passage 22 on the X-axis direction side (side 123 side), which is upstream of the flow direction of the measured gas 2. The sub-passage groove 150 is provided across two regions: the region on the Z-axis direction top side (lower surface 125 side) of the measuring section 113 relative to the circuit chamber 135, and the region on the X-axis direction side (side 124 side), which is downstream of the flow direction of the measured gas 2 in the main passage 22 relative to the circuit chamber 135.

[0048] A secondary passage 150 forms a secondary passage 134 through cooperation with a cover (not shown) covering the front of the measuring section 113. The secondary passage 150 has a first secondary passage 151 and a second secondary passage 152 branching off midway from the first secondary passage 151. The first secondary passage 151 is formed to extend along the X-axis direction of the measuring section 113 between a secondary passage inlet 131 opening onto one side 123 of the measuring section 113 and a first outlet 132 opening onto the other side 124 of the measuring section 113. The first secondary passage 151, through cooperation with the cover, forms a first secondary passage 134A, which draws in the measured gas 2 flowing within the main passage 22 from the secondary passage inlet 131 and returns the drawn-in measured gas 2 from the first outlet 132 back to the main passage 22. The first secondary passage 134A has a flow path extending from the secondary passage inlet 131 along the flow direction of the measured gas 2 within the main passage 22 and connecting to the first outlet 132.

[0049] The second auxiliary passage 152 branches off midway from the first auxiliary passage 151, bends towards the base end (flange side) of the measuring section 113, and extends along the Z-axis direction of the measuring section 113. Furthermore, at the base end of the measuring section 113, it bends towards the other side (side 124 side) in the X-axis direction of the measuring section 113, makes a U-shaped turn towards the top end of the measuring section 113, and extends again along the Z-axis direction of the measuring section 113. Moreover, in front of the first outlet 132, it bends towards the other side (side 124 side) in the X-axis direction of the measuring section 113, and is subsequently provided 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 2 in the main passage 22. The second outlet 133 has an opening area 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 compared to the first outlet 132.

[0050] The second secondary passage 152, in cooperation with the cover 200, forms a second secondary passage 134B. The second secondary passage 134B branches off from the first secondary passage 134A, allowing the incoming measured gas 2 to pass through and return to the main passage 22 from the second outlet 133. The second secondary passage 134B has a reciprocating flow path along the Z-axis direction of the measuring section 113. That is, the second secondary passage 134B has a forward passage 134B1 that branches off midway from the first secondary passage 134A and extends towards the base end of the measuring section 113 (away from the first secondary passage 134A), and a return passage 134B2 that turns back at the base end of the measuring section 113 (the end of the forward passage 134B1) and extends towards the top end of the measuring section 113 (closer to the first secondary passage 134A). The return passage section 134B2 is located downstream of the flow direction of the measured gas 2 in the main passage 22 compared to the secondary passage inlet 131, and has a flow path connected to a second outlet 133 that opens toward the downstream side of the flow direction of the measured gas 2.

[0051] A flow sensor 311 is disposed midway through the second auxiliary passage 134B toward the passage section 134B1. Since the second auxiliary passage 134B is formed as a reciprocating passage extending along the length direction of the measuring section 113, a longer passage length is ensured, reducing the impact on the flow sensor 311 in the event of pulsation within the main passage. The flow sensor 311 is disposed on a chip package 310, which is mounted on the circuit board 300.

[0052] Figure 3 This is a front view of the circuit board on which the chip package of the first embodiment is mounted. Figure 4 yes Figure 3 A schematic diagram of the AA-line section from the perspective. Figure 8 This is a rear view of the chip package in the first embodiment.

[0053] The circuit board 300 has circuit components such as a chip package 310, a pressure sensor 320, an intake air temperature sensor 321, and a humidity sensor 322 mounted on its mounting surface. The circuit board 300 has a roughly rectangular shape when viewed from above. Figure 2 As shown, the circuit board 300 is arranged in the measuring section 113 such that it extends from the base end to the top end of the measuring section 113 in the length direction and from the side 123 to the side 124 of the measuring section 113 in the width direction.

[0054] The circuit board 300 has a main 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 through passage 134B1 of a second secondary passage 134B, each extending from the main body 301 in the same plane. An intake air temperature sensor 321 is mounted at the top 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 chip package 310 in the through passage 134B1 of the second secondary passage 134B.

[0055] The chip package 310 has a resin package structure formed by molding a flow sensor 311, an LSI, and a lead frame with resin. The flow sensor 311 and the LSI are mounted on the lead frame. The chip package 310 is formed by sealing the flow sensor 311 with resin in a manner that exposes the diaphragm of the flow sensor 311. The chip package 310 has a package body 312 with a flat plate shape and a specified plate thickness formed from molding resin. The base end portion 312A of the package body 312 of the chip package 310 is disposed within a circuit chamber 135, and the top end portion 312B of the package body 312 protrudes and is disposed in a second secondary passage groove 152. The chip package 310 is electrically connected to the circuit board 300 via a fixing portion and is mechanically fixed.

[0056] A plurality of connecting terminals 313 are provided at the base end 312A of the package body 312. The plurality of connecting terminals 313 are provided from both ends of the base end 312A of the package body 312 in the width direction along the width direction of the package body 312 in a direction away from each other, and the top tip of each connecting terminal 313 is bent toward the thickness direction of the base end 312A and is positioned at a position that protrudes further than the back surface 318 of the base end 312A.

[0057] The top end 312B of the package body 312 is disposed opposite to the third protrusion 304 of the circuit board 300 within the passage portion 134B1 of the second secondary passage 134B. A groove is formed in the middle of the top end 312B of the package body 312 by a pair of passage walls 314. The pair of passage walls 314 are formed on the back surface 315 of the top end 312B of the package body 312, extending throughout the width direction of the package body 312. A flow sensor 311 is disposed at the middle position in the extension direction, exposed on the bottom surface of the groove.

[0058] The chip package 310 is disposed on the housing 100 with a pair of passage walls 314 extending along the passage portion 134B1 of the second sub-passage 134B. The chip package 310 is configured such that the flow sensor 311 is opposite to the third protrusion 304, which is part of the circuit board 300. Thus, a passage D is formed between the recess of the package body 312 and the third protrusion 304 of the circuit board 300. The gas to be measured 2 flowing through the second sub-passage 134B passes through the passage D, and the flow rate of the gas to be measured 2 is detected by the flow sensor 311.

[0059] The chip package 310 is fixed to the circuit board 300 by soldering the connection terminals 313 onto the circuit board 300. That is, the soldered portion constitutes a fixing part that electrically connects and mechanically fixes the chip package 310 to the circuit board 300. However, the method of fixing the chip package 310 to the circuit board 300 is not limited to soldering. For example, a press-fitting method can be used, in which multiple connection terminals are formed by press-fitting terminals and connected by inserting these press-fitting terminals into through holes provided in the circuit board 300, or a method can be used to apply a conductive adhesive such as silver paste to bond multiple connection terminals 313 to the connection pads of the circuit board 300 for fixing.

[0060] Since the chip package 310 is configured such that the end of the connection terminal 313 protrudes further in the thickness direction than the back surface 318 of the base end 312A of the package body 312, the chip package 310 is fixed on the circuit board 300 by soldering the connection terminal 313 onto the circuit board 300, with a predetermined gap formed between the back surface 318 of the base end 312A of the package body 312 and the mounting surface of the main body 301 of the circuit board 300.

[0061] The chip package 310 in this embodiment is as follows: Figure 4 As shown, the two sides of the passage wall 314, namely the back surface 318 of the base end portion 312A of the package body 312 and the back surface 315 of the top end portion 312B of the package body 312, are coplanar. A protrusion 316 protruding from the back surface 315 is provided on the back surface 315 of the top end portion 312B of the package body 312. The protrusion 316 is formed by molding resin forming the package body 312 and is formed by making a part of the passage wall 314, which is a resin part, protrude.

[0062] The protrusion 316 has a shape that, when the base end portion 312A of the chip package 310 is disposed on the main body portion 301 of the circuit board 300, contacts the third protrusion 304 of the circuit board 300 and supports the top end portion 312B of the chip package 310. The portion of the protrusion 316 that contacts the circuit board 300 is located on the side closer to the flow sensor 311 compared to the fixing portion where the chip package 310 is fixed to the circuit board 300. Specifically, in Figure 4 In the illustrated embodiment, the protrusion 316 is provided in the back surface 315 of the top portion 312B of the package body 312, protruding further towards the top end of the package body 312 than the recess. The flow sensor 311 is located between the fixing portion that fixes the chip package 310 to the circuit board 300 and the protrusion 316 that contacts the circuit board 300.

[0063] Therefore, when the chip package 310 is soldered and fixed to the circuit board 300, the base end 312A of the package body 312 is supported by the connecting terminal 313, and the top end 312B of the package body 312 is supported by the protrusion 316. By supporting both ends of the package body 312 on the circuit board 300, the posture of the package body 312 relative to the circuit board 300 can be stabilized. Thus, it is possible to prevent the top end 312B of the package body 312 from moving laterally towards or away from the circuit board 300, and to prevent the chip package 310 from being soldered and fixed to the circuit board 300 in an angle tilted relative to a reference.

[0064] Furthermore, the protrusion 316 is not limited to molding resin, and can be any component that can contact the third protrusion 304 of the circuit board 300 to support the top end 312B of the chip package 310. For example, it can be formed by making a part of the lead frame protrude from the package body 312.

[0065] Figure 13 This is a diagram illustrating a comparative example, and is related to... Figure 4 The corresponding diagram.

[0066] exist Figure 13 In the case of the comparative example shown, with Figure 4 Compared to the structure shown, no protrusion 316 is provided on the back side 315 of the top end 312B of the package body 312, and the top end 312B of the package body 312 is in a state of floating off the circuit board 300. That is, the chip package 310' of the comparative example is in a state where the base end 312A of the package body 312 is cantilevered relative to the circuit board 300.

[0067] Therefore, when the chip package 310' is soldered and fixed onto the circuit board 300, the posture of the package body 312 is unstable, such as... Figure 13As indicated by the middle arrow, the top portion 312B of the package body 312 may move towards or away from the circuit board 300. Furthermore, when the chip package 310 is soldered and fixed to the circuit board 300 in an angle tilted from the reference, the size of the passage D changes, which may cause deviations in the flow detection accuracy of each component.

[0068] In contrast, in this embodiment, such as Figure 4 As shown, a protrusion 316 is provided at the top end 312B of the package body 312, and the protrusion 316 contacts the circuit board 300 to support the top end 312B. Therefore, both the base end 312A and the top end 312B of the package body 312 can be supported. Thus, the orientation of the package body 312 relative to the circuit board 300 can be stabilized, and when the chip package 310 is soldered and fixed to the circuit board 300, it can be prevented from being soldered and fixed to the circuit board 300 in an tilted orientation. Therefore, the size of the passage D can be kept constant, and deviations in the flow detection accuracy of each component can be prevented.

[0069] Figures 5 to 7 This is a diagram illustrating other variations, and is related to... Figure 4 The corresponding diagram.

[0070] Figure 5 The modified example shown has the following structure: instead of providing the protrusion 316, a facing surface 315', which serves as one side of the passage wall 314, is formed on the back surface 315 of the top portion 312B of the package body 312 at a position protruding from the back surface 318 of the base end portion 312A. This facing surface 315' contacts the surface of the third protrusion 304 of the circuit board 300. According to this modified example, it is possible to suppress the tilting of the top portion 312B side of the package body 312 towards or away from the circuit board 300 compared to the base end portion 312A, and to enable the package body 312 to be supported on the circuit board 300 in a stable posture.

[0071] Figure 6 The modified example shown has the following structure: instead of providing a protrusion 316, a protruding protrusion 317 is provided on the back surface 315 of the top portion 312B of the package body 312, on the side closer to the base end portion 312A than the passage wall 314, so that the protrusion 317 contacts the third protrusion 304 of the circuit board 300. According to this modified example, with Figure 5 Similarly, the modified example shown can suppress the tilting of the top end portion 312B side of the package body 312 towards the circuit board 300 compared to the base end portion 312A, and can enable the package body 312 to be supported on the circuit board 300 in a stable posture.

[0072] Figure 7 The variation shown will Figure 5 The structure shown and Figure 6 The structures shown are combined to bring the aforementioned opposing surfaces 315' and protrusions 317 into contact with the circuit board 300. Specifically, they have two structures: a structure in which the opposing surface 315' of the back surface 315 of the top portion 312B of the package body 312 is formed at a position that protrudes further than the back surface 318 of the base end portion 312A compared to the passage wall 314, and this opposing surface 315' contacts the third protrusion 304 of the circuit board 300; and a structure in which a protruding protrusion 317 is provided on the portion of the back surface 315 of the top portion 312B of the package body 312 that is closer to the base end portion 312A than the passage wall 314, and this protrusion 317 contacts the third protrusion 304 of the circuit board 300.

[0073] According to this modified example, since it has a structure that allows both sides of the passage wall 314, namely the opposing surface 315' and the protrusion 317, to contact the circuit board 300, it is possible to more reliably suppress the tilting of the top end portion 312B side of the package body 312 towards the circuit board 300 compared to the base end portion 312A, and the package body 312 can be supported on the circuit board 300 in a stable posture.

[0074] Figures 9 to 11 This is a diagram illustrating other variations, and is related to... Figure 8 The corresponding diagram.

[0075] Figure 9 In the modified example shown, two protrusions 316 are provided on the back surface 315 of the top end 312B of the package body 312, at a position closer to the top end 312B than the passage wall 314. The two protrusions 316 are separately arranged at positions separated along the width direction of the package body 312, which can suppress the tilting of the package body 312 in the width direction and enable the package body 312 to be supported on the circuit board 300 in a stable posture.

[0076] Figure 10 In the modified example shown, a protrusion 316 is provided on the back surface 315 of the top end portion 312B of the package body 312, closer to the top end portion 312B than the passage wall 314, and a protrusion 317 is provided on the side closer to the base end portion 312A than the passage wall 314. The protrusions 316 and 317 are positioned at the center of the package body 312 in the width direction, which can prevent the top end portion 312B of the package body 312 from tilting towards or away from the circuit board 300 compared to the base end portion 312A, and can ensure that the package body 312 is supported on the circuit board 300 in a stable posture.

[0077] Figure 11 The variation shown is that two are set respectively. Figure 10 Examples of protrusions 316 and 317 are shown. The two protrusions 316 and 317 are separately arranged at positions separated along the width direction of the package body 312, which suppresses the tilting of the package body 312 in the width direction and suppresses the tilting of the top end portion 312B side of the package body 312 towards the circuit board 300 compared with the base end portion 312A, so that the package body 312 can be supported on the circuit board 300 in a stable posture.

[0078] According to the flow measuring device 20 in this embodiment, the base end portion 312A and the top end portion 312B of the package body 312 can be supported on the circuit board 300, and the posture of the package body 312 relative to the circuit board 300 can be stabilized. Therefore, when the chip package 310 is soldered and fixed to the circuit board 300, it is possible to prevent the chip package 310 from being soldered and fixed to the circuit board 300 in an inclined posture, to keep the size of the passage D constant, and to prevent deviations in the flow detection accuracy of each component.

[0079] <Second Implementation> Figure 12 This is a front view of the circuit board on which the chip package of the second embodiment is installed, and is related to... Figure 3 The corresponding diagram.

[0080] The feature of this embodiment is that a mounting substrate 330 for mounting the flow sensor 311 is used instead of a chip package 310. In the above embodiments, the case of mounting the chip package 310 with the flow sensor 311 on the circuit board 300 is described as an example, but as long as the flow sensor 311 is fixed on the circuit board 300 in a manner opposite to the third protrusion 304 of the circuit board 300, the chip package 310 is not a necessary element.

[0081] The base end of the substrate body 331 of the mounting substrate 330 is fixed to the main body 301 of the circuit board 300, and the top end protrudes and is disposed in the second secondary passage 134B. A flow sensor 311 is disposed on the back side of the mounting substrate 330 and is disposed opposite to the third protrusion 304 of the circuit board 300 with a predetermined gap, so that the gas 2 to be measured flowing into the second secondary passage 134B can pass through. Furthermore, a protrusion 333 protruding from the back side of the substrate body 331 toward the circuit board 300 is provided at the top end of the substrate body 331. The protrusion 333 contacts the third protrusion 304 of the circuit board 300 and supports the top end of the substrate body 331.

[0082] Furthermore, in this embodiment, the case where the protrusion 333 is provided on the substrate body 331 of the mounting substrate 330 is described as an example, but any structure that can support the top end of the mounting substrate 330 and suppress the tilting of the substrate body 331 relative to the third protrusion 304 of the circuit board 300 is acceptable. For example, it may also be a structure in which the third protrusion 304 of the circuit board 300 protrudes into the mounting substrate 330, contacts the back side of the substrate body 331 of the mounting substrate 330, and supports the top end of the mounting substrate 330.

[0083] The mounting substrate 330 has a substrate body 331 and a plurality of connection terminals 332 protruding from the substrate body 331. The mounting substrate 330 is fixed to the circuit board 300 by connecting the plurality of connection terminals 332. As a method of fixing the plurality of connection terminals 332 to the circuit board 300, soldering can be used for example. However, the fixing method is not limited to soldering. A press-fitting method can also be used, in which a plurality of connection terminals are formed by press-fitting terminals and connected by inserting these press-fitting terminals into through holes provided in the circuit board 300, or a method of fixing the plurality of connection terminals 332 to the connection pads of the circuit board 300 by applying a conductive adhesive such as silver paste.

[0084] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the spirit of the invention as set forth in the claims. For example, the above embodiments are described in detail for the purpose of easily understanding the present invention and are not necessarily limited to having all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of a certain embodiment. Furthermore, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0085] Symbol Explanation

[0086] 300 circuit board (substrate)

[0087] 304 Third Protrusion (Part of the Substrate)

[0088] 310 chip package (resin package)

[0089] 311 Flow Sensor (Flow Detection Element)

[0090] 312 package body

[0091] 312A base end

[0092] 312B top section

[0093] 313 connection terminal

[0094] 314 passage wall

[0095] 315 back

[0096] 316. Protrusion.

Claims

1. A flow rate measuring device, characterized in that, have: A resin encapsulation having a flow sensing element and forming a passage wall; and Circuit board on which the resin encapsulation is mounted The resin encapsulation is configured such that the flow detection element is opposite a portion of the circuit board. A portion of the resin portion of the resin encapsulation is mounted in contact with the circuit board. The flow detection element has a diaphragm. The resin encapsulation has a lead frame for mounting the flow sensing element. The flow sensing element is sealed with resin in a manner that exposes the diaphragm. A portion of the passage wall is in contact with the circuit board. The flow measuring device has a secondary passage for taking in a portion of the gas being measured flowing through the main passage, and a circuit chamber adjacent to the secondary passage that houses the circuit board. The circuit board has a protrusion extending from the circuit chamber to the secondary passage. The resin encapsulation is mounted on the circuit board, and the flow detection element is configured opposite to the protrusion of the circuit board.

2. The flow measuring device according to claim 1, characterized in that, The resin encapsulation has a base portion disposed at the base of the circuit chamber and a top portion disposed at the top of the secondary passage. A connection terminal for connecting to the circuit board is provided at the base end, and the flow detection element is provided at the top end.

3. The flow measuring device according to claim 2, characterized in that, The resin encapsulation has a groove extending along the secondary passage on the top surface opposite the circuit board, in which the flow detection element is exposed.

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