JP5455848B2 - Thermal flow sensor - Google Patents

Description

  The present invention relates to a thermal flow sensor provided with a sensor element by a heating resistor as a detection unit to detect a flow rate of air or the like flowing in an intake passage of an in-vehicle internal combustion engine, and particularly detects a temperature of intake air or the like. The present invention relates to a thermal flow sensor that integrates a temperature sensor to improve the reliability of the temperature sensor.

  In the field of automobile engine control, a flow sensor using a sensor element manufactured by using a micromachining technology on a semiconductor substrate such as silicon (Si) for the flow rate of air supplied to the engine has been proposed. As a flow sensor, there exists invention of the following patent document 1, for example. The configuration described in such a document is a secondary sensor in which the flow sensor element is arranged to protect the flow sensor element from moisture and dust contained in the flow rate in order to ensure reliability in use in a long-term automobile environment. In the passage, a configuration is disclosed in which a sub-passage is formed so that the direction in which the gas flows in from the inlet and the flow direction in the vicinity of the flow sensor element are different so that moisture and dust do not directly collide with the flow sensor element.

  In general, a temperature detection sensor element for detecting the temperature of intake air or the like is integrated with a flow sensor to detect two physical quantities in one sensor module. For example, there is an invention described in Patent Document 2 below. . The configuration described in Patent Document 2 discloses a configuration in which the temperature detection sensor element is arranged in the sub-passage.

JP 2009-122054 JP 2007-248137 A

  The engine room of an automobile is likely to be hotter than the fluid temperature when the engine is operating. For example, even when the intake air temperature is 25 ° C., members constituting the main passage in which the sensor module is mounted are In some cases, the temperature may be about 50 to 80 ° C., and this heat is transmitted from the sensor module mounting portion to the sensor side. Here, a metal terminal is insert-molded in the resin housing member constituting the sensor module for electrical connection with the temperature detection sensor element. The linear expansion coefficient of this terminal and the surrounding resin Therefore, the terminal is deformed by the transmitted heat. Therefore, the terminal to which the lead of the temperature detection sensor element is welded is desirably arranged at a place where it is easily cooled by the fluid, and the position facing the sub-passage is desirable as described in Patent Document 2.

  However, on the other hand, when applying a sensor element manufactured using micromachining technology on a semiconductor substrate, as described in Patent Document 1, a sub-passage shape for protecting from dust or the like is necessary, In this case, the flow path width of the sub passage becomes very narrow. In the flow sensor having such a sub-passage, when the temperature detection sensor element is disposed at a position facing the sub-passage, the resin material constituting the sub-passage is deformed by the deformation due to the thermal stress of the terminal, and the flow sensor element The measurement will be affected and the accuracy will deteriorate.

  The present invention has been made to solve such a problem, and an object of the present invention is to detect a temperature at a position where a sub-passage is not deformed in a flow sensor to which a flow sensor element manufactured by semiconductor technology is applied. Even if the metal terminal that is connected to the temperature detection sensor element is deformed by thermal stress, the lead that supports the temperature detection sensor element is prevented from being deformed and the temperature detection reliability is improved. Another object of the present invention is to provide a flow rate sensor module in which the temperature detection sensor element is integrated.

  In order to achieve the object, the thermal flow sensor according to the present invention has the following means. That is, in one aspect of the flow sensor according to the present invention, the terminal to which the temperature detection sensor element is welded is disposed at a position closer to the side where the sensor module is inserted and mounted than the position of the sub-passage. With this configuration, the sub-passage in which the flow rate sensor element is arranged can be configured not to be affected by the deformation of the metal terminal to which the temperature detection sensor element is electrically connected.

  On the other hand, since a metal terminal is arrange | positioned in the position near a sensor module attachment part, it becomes easy to receive the heat conduction influence from the duct which comprises a main channel | path. In order to prevent an influence on the temperature detection sensor element due to the thermal influence, a dummy area is formed in an area where the resin housing member of the metal terminal is insert-molded. With this configuration, even when the metal terminal is deformed under the influence of heat, it is possible to make a difference in how the first terminal and the second terminal are affected by the heat. By utilizing this difference, the deformation of the region where the lead supporting the temperature detection sensor element of the first terminal and the second terminal is electrically connected can be relatively reduced. This makes it possible to provide a flow sensor integrated with a temperature detection sensor element that can provide a reliable temperature signal output even during long-term use.

  According to the present invention, in a flow sensor to which a flow sensor element manufactured by semiconductor technology is applied, the temperature detection sensor element is disposed at a position where the sub-passage is not deformed, and the metal is electrically connected to the temperature detection sensor element. Even if the terminal is deformed by thermal stress, it is possible to provide a flow rate sensor module in which a temperature detection sensor element integrated with a temperature detection sensor element that prevents the deformation of the lead supporting the temperature detection sensor element and improves the reliability of temperature detection can be provided. .

The cross-sectional view which shows the flow sensor of one Embodiment of this invention. AA sectional drawing of FIG. The fragmentary sectional view which has arranged the flow sensor of one embodiment of the present invention in the main passage. The terminal part enlarged view of one Embodiment of this invention. The analysis result which shows the effect of this invention. The figure which shows the insert area | region of the terminal part of one Embodiment of this invention. The cross-sectional view which shows the flow sensor of one Embodiment of this invention. The enlarged view of the broken line P of FIG. BB sectional drawing of FIG. The terminal part enlarged view of other embodiment of this invention. The terminal part enlarged view of other embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 is a partial cross-sectional view showing a sensor module 23 in the present embodiment, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, and FIG. 3 is a partial cross-section showing a state where the sensor module 23 of the present invention is installed in the main passage 20. The figure is shown.

  The flow sensor element 1 forms a thin film portion on a silicon substrate, and forms a heating resistor on the thin film portion. As the material of the heating resistor, single crystal silicon doped with impurities, polycrystalline silicon, metal material, or the like is used.

  The flow sensor element 1 is adhesively mounted on a support and is electrically connected to a circuit board mounted on the support. The support has a plate shape made of resin, ceramic, or metal. When the support is made of a ceramic material, the support and the circuit can be integrated, so that the adhesive mounting can be reduced and the reliability can be improved.

  In FIG. 2, the structure which applied the multilayer ceramic substrate 16 as a support body is shown. A rectangular recess 8 is formed in the multilayer ceramic substrate 16, and the flow sensor element 1 is mounted in the rectangular recess 8. By being mounted in the rectangular recess 8 in this way, the flow is stable and flows on the surface of the flow sensor element 1, so that a stable flow signal can be obtained.

  The multilayer ceramic substrate 16 can form the rectangular recess 8 by using a part of the plurality of layers constituting the multilayer ceramic substrate 16. In addition, the multilayer ceramic substrate 16 has a circuit area formed in a small size by forming a circuit conductor on the interior and mounting an adjustment LSI 15 and chip parts necessary for driving the flow sensor element 1 on the surface. can do.

  The flow sensor element 1 is electrically connected to the multilayer ceramic substrate 16 by wire bonding. The adjustment LSI 15 is also electrically connected to the multilayer ceramic substrate 16 by wire bonding.

  The laminated ceramic substrate 16 is mounted on the resin base member 17 with a silicone adhesive. Thereafter, the resin housing member 18 is bonded with a silicone adhesive. The resin housing member 18 is electrically connected to the multilayer ceramic substrate 16 and is supplied with power for driving the sensor module, and a connector terminal for inputting / outputting signals from the sensor module, and a temperature detection sensor. First and second terminals 3 and 4 for welding elements are insert-molded. As shown in FIG. 1, the temperature detection sensor element 2 is electrically joined to the first terminal 3 and the second terminal 4 via a lead 5 by welding. The first terminal 3 and the second terminal 4 are connected to the multilayer ceramic substrate 16 by aluminum wire bonding.

  Next, the resin cover member 19 is bonded with an epoxy adhesive. The resin housing member 18, the resin base member 17, and the resin cover member 19 form a sub passage 9, and the flow sensor element 1 mounted on the multilayer ceramic substrate 16 is disposed in the sub passage 9.

  The sub-passage 9 takes in a part of the fluid flowing through the main passage 20 from the inlet opening on the upstream side of the flow. As shown in FIG. 1, the fluid flowing in from the inlet reaches the position of the flow sensor element 1. In between, the flow direction is turned 180 degrees. With this configuration, dust, fouling substances, water, and the like contained in the fluid collide with the wall of the sub-passage 9 due to inertia and lose kinetic energy. Thereby, the direct collision with the flow sensor element 1 can be reduced significantly, and reliability can be improved.

  Further, in the environment around the engine, the fluid flowing through the main passage 20 is not always stable due to the recent adoption of variable valve timing or the like, and pulsation occurs. A reverse flow is generated from the side.

  In order to detect the flow rate accurately even under such circumstances, as in the sub-passage 9 shown in FIG. 1, an outlet is formed on the reverse flow side, and the upstream flow channel 10 and the downstream flow channel 11 are formed. A sub-passage 9 that is as symmetric as possible is effective in both the upstream and downstream directions. However, when adopting this configuration, as shown in FIG. 2, it is necessary to form the upstream flow path 10 and the downstream flow path 11 in a double structure within the range of the width of the sensor module 23. The width of the sensor module 23 is preferably 10 mm or less from the viewpoint of pressure loss. When the complicated sub-passage 9 is configured as shown in FIG. 2 in the limited width range of the sensor module 23 as described above, the sub-passage width is ½ or less of the width of the sensor module 23. Therefore, the deformation of the sub-passage 9 relatively greatly affects the measurement accuracy of the flow sensor element 1, and as described in Patent Document 2, the temperature detection sensor element is arranged in a region facing the sub-passage. It becomes difficult.

  Further, as shown in FIG. 2, the flow in the sub-passage 9 is divided into the front-side flow path 12 and the back-side flow path 13 on the flow sensor element 1 side by the multilayer ceramic substrate 16. Here, by adopting a configuration in which the flow speed of the back surface side flow path 13 is faster than the flow speed of the front surface side flow path 12, dust, fouling substances, water, and the like contained in the fluid are mainly flown by the back side flow due to inertial force. It flows into the road 13. Thereby, it can reduce significantly that dust etc. collide with the flow sensor element 1 directly, and can improve reliability. In addition, a throttle 14 for reducing the flow is formed at a position on the flow sensor element 1 of the resin housing member 18. The throttle 14 can obtain a state in which the disturbance of the fluid is reduced on the flow sensor element 1 and enables stable flow measurement. However, in this configuration as well, the width of the sub-passage 9 is ½ or less of the width of the sensor module 23, and the passage width is also narrowed by the aperture 14. Accordingly, the deformation of the sub passage 9 relatively greatly affects the measurement accuracy of the flow sensor element 1. Accordingly, it is difficult to adopt a configuration in which the temperature detection sensor element 2 is disposed in the region facing the sub passage 9.

  Therefore, for the sensor module 23 having the above-described configuration, it is desirable that the temperature detection sensor element 2 be installed at a position where the sub-passage 9 is not affected by deformation. Specifically, as shown in FIG. 3, it is desirable to arrange the temperature detection sensor element 2 outside the sub-passage. However, on the other hand, at a position close to the sensor module mounting portion 22, it is affected by heat conduction from the duct 21 that forms the main passage 20. Further, since heat conduction is transmitted from the sensor module mounting portion 22 in the insertion direction of the sensor module 23, the second terminal 4 is more affected by the heat conduction than the first terminal 3. Therefore, a difference occurs in the deformation amount due to the thermal stress between the second terminal 4 and the second terminal 4, and thus the lead 5 supporting the temperature detection sensor element 2 is also deformed. That is, the accuracy of the flow signal detected by the flow sensor element 1 is deteriorated.

  Therefore, the terminal shape of the present embodiment has a shape as shown in FIG. Here, FIG. 4 is an enlarged view of the vicinity of the first terminal 3 and the second terminal 4 in FIG. 1, and the hatched portion in FIG. 6 is the resin housing of the first terminal 3 and the second terminal 4. The region inserted in the member 18 is shown. As shown in FIGS. 4 and 6, in the terminal shape of the present embodiment, a dummy region 24 is added to the region inserted in the resin housing member 18 of the first terminal 3.

  Thus, by adding the dummy region 24, the first terminal 3 can be more positively affected by heat than the second terminal 4. Thereby, the difference of the influence by the heat by the 1st terminal 3 and the 2nd terminal 4 can be made small, the difference of the deformation amount by a thermal stress is made small, and, thereby, the stress added to the lead 5 is reduced. It becomes possible to do. In this way, relative deformation at the position where the lead 5 of the temperature detection sensor element 2 of each terminal is welded can be suppressed, and a reliable temperature signal can be provided even during long-term use. In addition, since the sub-passage 9 is not affected by deformation, deterioration in accuracy of the flow rate signal detected by the flow rate sensor element 1 can be suppressed.

  Next, another embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected about the part which overlaps with embodiment described previously, and detailed description is abbreviate | omitted. Hereinafter, different parts will be described.

  FIG. 7 is a partial cross-sectional view showing the sensor module 23 in the present embodiment, and FIG. 8 is an enlarged view of a region indicated by a broken line P in FIG. Moreover, FIG. 9 shows the BB cross section of FIG.

  As shown in FIG. 7, the region where the first terminal 3 and the second terminal 4 are insert-molded is a position close to the boundary between the circuit chamber 25 and the sub-passage 9. Therefore, it is difficult to make the thickness of the resin uniform in the region where the first terminal 3 and the second terminal 4 are insert-molded.

  As shown in FIG. 9, since the thickness of the resin is different, the cooling rate of the resin is different between the first terminal 3 and the second terminal 4 at the time of molding. A difference will arise in the thermal stress concerning a terminal. Due to this stress difference, the first terminal 3 and the second terminal 4 are deformed by different deformation amounts after molding. However, in the present embodiment, as shown in FIGS. 8, 9, and 10, the second terminal 4 is disposed in the region where the resin thickness of the resin housing member 18 is small, and the first terminal is disposed in the region where the resin thickness is large. The terminal 3 is arranged, and when the area of the dummy region 24 of the first terminal 3 is S1 and the area of the dummy region 24 of the second terminal 4 is S2, S1> S2. In this way, by changing the areas of the dummy regions of the first terminal and the second terminal, it is possible to give a difference in how to receive the thermal stress from the resin to each terminal. By utilizing this difference, the deformation of the region where the lead 5 supporting the temperature detection sensor element 2 of the first terminal 3 and the second terminal 4 is electrically connected can be relatively reduced.

  In addition, when used as the sensor module 23, the first terminal 3 and the second terminal 4 receive different heat due to the difference in resin thickness even with respect to the thermal influence transmitted from the sensor module mounting portion 22. Therefore, by changing the area of the dummy region 24, it is possible to make a difference in how the first terminal 3 and the second terminal 4 are affected by heat. By utilizing this difference, the deformation of the region where the lead 5 supporting the temperature detection sensor element 2 of the first terminal 3 and the second terminal 4 is electrically connected can be relatively reduced. Features. This makes it possible to provide a flow sensor integrated with a temperature detection sensor element that can provide a reliable temperature signal output even during long-term use.

  Further, when the sensor module 23 is used in an automobile environment, heat is transmitted from the sensor module mounting portion 22, while the sensor module 23 is cooled by the fluid flowing through the main passage 20. Accordingly, the temperature of the sensor module 23 decreases as the distance in the insertion direction from the sensor module mounting portion 22 increases. Therefore, as shown in FIG. 8, since the first terminal 3 is more easily cooled than the second terminal 4, there is a difference in the thermal effect received from the mounting surface, and there is also a difference in the manner of deformation. . Here, by giving a difference in the area of the dummy region, it is possible to make a difference in how the first terminal and the second terminal are affected by heat. By utilizing this difference, the deformation of the region where the lead 5 supporting the temperature detection sensor element 2 of the first terminal 3 and the second terminal 4 is electrically connected can be relatively reduced. In this case, as shown in FIG. 8, FIG. 9, and FIG. 10, the second terminal 4 is disposed in the region where the resin thickness of the resin housing member 18 is small, and the first terminal 3 is disposed in the region where the resin thickness is large. When the area of the dummy region 24 of the first terminal 3 is S1 and the area of the dummy region 24 of the second terminal 4 is S2, S1> S2. This makes it possible to provide a flow sensor integrated with a temperature detection sensor element that can provide a reliable temperature signal output even during long-term use.

  In another more preferable aspect, the first and second terminals are provided with a current flowing region and a non-flowing region for obtaining the output of the temperature sensor element, and the region where the current does not flow is set as a dummy region. It is characterized by. The purpose of the dummy region is to positively receive heat to control the deformation of the terminal and suppress the deformation of the temperature detection sensor element lead. However, the terminal is also required to transmit electrical signals of the circuit and temperature detection sensor element. Therefore, it is possible to further improve the reliability by dividing the region into a region that is actively deformed by receiving heat and a region that transmits an electrical signal.

  Furthermore, another embodiment of the present invention will be described with reference to FIG. In addition, about the part which overlaps with embodiment described previously, it shall be the same as that of previous embodiment, and detailed description is abbreviate | omitted. Hereinafter, the shape of the terminal of this embodiment which is a different part is demonstrated.

  In the present embodiment, as shown in FIG. 11, in order to further reduce the deformation of the first terminal welding position 6 and the second terminal welding position 7 due to the thermal stress of the first terminal 3 and the second terminal 4. The dummy area 24 is provided in the first terminal 3, and only the area of the dummy area 24 of the second terminal 4 is configured to have a small distance from the first terminal 3. Thereby, since the dummy region 24 of the first terminal 3 is positively deformed by heat, the first terminal welding position 6 and the second terminal 2 are brought close to the second terminal 4 only at the position where the dummy area 24 is easily deformed. The relative deformation of the terminal welding position 7 can be prevented. Therefore, the stress on the lead 5 can be relaxed. Specifically, it is effective that the approaching distance is in the range of 0.3 to 0.7 mm.

  FIG. 5 shows an example of the result of thermal stress analysis in a terminal to which the present invention is applied. In this example, the maximum stress generated is about 170 MPa. On the other hand, in the example of the result when the dummy region shown in the present invention is not provided, the pressure is about 230 MPa or more. That is, the generated stress can be reduced to about 73% by the configuration of the terminal of the present invention.

DESCRIPTION OF SYMBOLS 1 Flow rate sensor element 2 Temperature detection sensor element 3 1st terminal 4 2nd terminal 5 Lead 6 1st terminal welding position 7 2nd terminal welding position 8 Rectangular recessed part 9 Subchannel 10 Upstream channel 11 Downstream Side channel 12 Front side channel 13 Back side channel 14 Aperture 15 Adjustment LSI
16 Laminated ceramic substrate 17 Resin base member 18 Resin housing member 19 Resin cover member 20 Main passage 21 Duct 22 Sensor module mounting portion 23 Sensor module 24 Dummy area 25 Circuit chamber

Claims (4)

A resin housing member that constitutes a sub-passage that is inserted into the main passage and into which a part of the flow rate of the main passage flows, a flow sensor element that detects a flow rate disposed in the sub-passage, Circuit board connected electrically, a temperature detection sensor element for detecting temperature having two leads for transmitting an electric signal, and the two leads are electrically and mechanically connected to each other, and the circuit board A thermal flow sensor having a first terminal and a second terminal that are electrically connected to each other and are insert-molded in the resin housing member;
The temperature detection sensor element is provided outside the auxiliary passage,
The first terminal or the second terminal is provided with a dummy region in a region inserted in the resin housing member ,
The thickness of the resin housing member in the region where the first terminal and the second terminal are inserted into the resin housing member is different between the first terminal and the second terminal, and the resin When the first terminal is disposed in a region where the resin thickness of the housing member is large and the second terminal is disposed in a region where the resin thickness of the resin housing member is small,
The thermal flow rate is characterized in that the dummy region area is provided so that S1> S2, where S1 is the dummy region area of the first terminal and S2 is the dummy region area of the second terminal. Sensor. The first terminal is arranged at a position farther from the wall surface of the main passage than the second terminal, and the dummy area area of the first terminal is S1, and the dummy area of the second terminal is S2. When thermal flow sensor according to claim 1, characterized in that a dummy region area so that S1> S2. The first and second terminals are provided with a current flow region and a non-flow region for obtaining an output of the temperature detection sensor element, and the dummy region is provided in the current non-flow region. Item 3. The thermal flow sensor according to Item 1 or 2 . In the first terminal, one of claims 1 to 3, characterized in that the dummy area of the first terminal is to reduce the distance of the only range which is provided a first terminal and the second terminal The thermal flow sensor described in 1.

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