Air physical quantity sensor

A sensor body has a body recess portion, in which a sensor element is housed and the body recess portion opens at a body opening portion. A sensor cover has a cover window which communicates between the intake passage and the body opening portion, and the sensor cover covers the sensor body. A sensor filter is provided with a sensor peripheral portion which extends along a virtual surface. In a projection view with respect to the virtual plane the body opening portion and the cover window are positioned within a filtering area which is defined as an inner side of a contour of the filter peripheral portion, such that the filter peripheral portion contacts the sensor body and the sensor cover.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2016-212115 filed on Oct. 28, 2016, the disclosure of which is incorporated herein by reference.

FIELD

The present disclosure relates to an air physical quantity sensor that detects a specified quantity of an air flowing in a fluid passage.

BACKGROUND

Conventionally, an air physical quantity sensor has a sensor element for outputting the detected signal in accordance with a specified quantity, the sensor element housed in a recess portion of a sensor body, which opens at an opening portion.

In the sensor as an air physical quantity sensor as shown in Japanese Patent application No. 2015-187603 (referred to as patent document 1, hereinafter), the atmosphere sensor has a sensor filter in a sensor case. The moisture permeable film is bonded to the case by a welding method.

The moisture permeable film having the shape of a circle or an oval and the welded part having the shape of a ring make bonded strength between the welded part and the bottom surface of the sensor case uniform. Since a restoring force continually acts to the welded part and the welded part is easily removed, the moisture permeable film is separated from the case. The moisture permeable film having extensibility make the mesh enlarge, and the filter performance is reduced.

The present disclosure is made in view of the above matters, and it is an object of the present disclosure to provide an air physical quantity sensor, a sensor filter of which is prevented to remove and to deform.

SUMMARY

A sensor body has a body recess portion, in which a sensor element is housed and the body recess portion opens at a body opening portion. A sensor cover has a cover window which communicates between the intake passage and the body opening portion, and the sensor cover covers the sensor body. A sensor filter is provided with a sensor peripheral portion which extends along a virtual surface. In a projection view with respect to the virtual plane the body opening portion and the cover window are positioned within a filtering area R which is defined as an inner side of a contour of the filter peripheral portion, such that the filter peripheral portion contacts one of the sensor body and the sensor cover.

The filter peripheral portion positions between the sensor body and the sensor cover and contacts one of the sensor body and the sensor cover, such that a shape of the sensor filter extending along the virtual plane can be maintained and the sensor filter is prevented to remove from between the sensor body and the sensor cover.

The body opening portion is positioned in the cover window in the projection view.

In the projection view with respect to the virtual plane, the body opening portion is positioned in the cover window within the filtering area. The air flowing through the cover window and the sensor filter from the intake passage entries into the body recess from the body opening portion without being blocked by the sensor body around the body opening portion. The air from the intake passage easily reaches to the sensor element in the body recess. Since the sensor filter extending along the virtual plane is interposed between the sensor body and the sensor cover, the sensor filter is positioned near to the sensor element in the body recess. As a result, since an inner volume of the body recess is small, a time of the air flowing from the intake passage to the sensor element can be shortened. Accordingly, since the air easily reaches to the sensor element and the air reaching time to the sensor element is also minimized, the detection response of the sensor element can be enhanced.

DETAILED DESCRIPTION

In the following, embodiments of the present disclosure are described with reference to the accompanying drawings. In the description and in the drawings, identical or similar components bear the same reference numerals or characters. If a part of the features in each embodiment is explained, the remaining part of the features may apply to the remaining part of the features in other embodiments. In each embodiment, a combination of the features is disclosed in the specification, and in addition to the combination, the features in the embodiments may be combined, even if such combinations are not apparently disclosed in the specification.

First Embodiment

As shown inFIG. 1, an air physical quantity sensor10is applied to an air flow detection unit2in an internal combustion engine.

The air flow detection unit2is attached to an attachment opening4aof an intake air duct4formed as an intake passage3in the internal combustion engine. The air flow detection unit2is provided with a flow detection body5located in the intake passage3. As shown inFIGS. 2 and 3, the flow detection body5has a bypass passage6in a detection portion5a. Along an arrow of the broken line shown inFIGS. 1 and 3, a part of the intake air flowing into a cylinder of the internal combustion engine through the intake passage3is distributed in the bypass passage6from the intake passage3.

As shown inFIG. 3, the bypass passage6comprises a first passage portion7and a second passage portion8. The straight first passage portion7includes an inlet7aand an outlet7b, both of which open the intake passage3. In a direction of an arrow of the dashed line shown inFIG. 3, the first passage portion7introduces the intake air in a substantially same direction along the intake passage3from the inlet7ato the outlet7b. The curved second passage portion8comprises an inlet8afacing a middle part of the first passage portion7, and an outlet8bfacing the intake passage3, such that the second passage portion8is branched from the first passage portion7. In the direction of the arrow of the dashed line shown inFIG. 3, the second passage portion8whirls the intake air in an opposite direction with respect to the intake passage3and then flows the intake air in a same direction along the intake passage3between the inlet8aand the outlet8b.

The flow detection body5further includes a flow sensor9and the above mentioned bypass passage6. A sensor element9aof the flow sensor9is exposed to the second passage portion8. The sensor element9aoutputs a flow signal depending on an amount of intake air flowing in the second passage portion8. The flow sensor9includes a circuit module9b, which calculates the amount of the intake air in the intake passage3based on the flow signal outputted from the sensor element9a. The amount of intake air calculated by the circuit module9bis transmitted to an engine control unit provided outside of the intake passage3via a signal transmission through a plurality of terminals5bin the flow detection body5. The flow detection body5detects the amount of the intake air flowing in the intake passage3by means of the sensor element9a.

As shown inFIGS. 1 and 2, the air physical quantity sensor10is integrally provided with the air flow detection unit2. The air physical quantity sensor10is arranged outside of the bypass passage6such that the sensor10is exposed to the intake passage3referred to as flow passage. The air physical quantity sensor10is configured to have a predetermined width extending in the intake air flow direction in the intake passage3in the direction of the arrow of the dashed line shown inFIG. 3, and the air physical quantity sensor10is configured to be formed as thick belt shape extending in a vertical direction with respect to the intake air flow direction as a whole. X direction is defined as the intake air flow direction in the intake passage3. Z direction is defined as a longitudinal direction in which the air physical quantity sensor10extends in the vertical direction with respect to the flow direction. Y direction is defined as a vertical direction with respect to both X direction and Z direction.

As shown inFIGS. 4 and 5, the air physical quantity sensor10includes a sensor case20, a reinforced plate30, a sensor substrate40, a sensor unit50, a terminal60, a circuit module70, and a potting resin portion80. For better understanding, a part of the potting resin portion80is shown inFIG. 4.

The sensor case20is made of a hard resin, such as polyphenylene sulfide (PPS). The sensor case20is formed as thick belt shape, corresponding to a whole contour of the air physical quantity sensor10. The sensor case20has a connector portion22and a recess portion24. The connector portion22is provided at one end in Z direction as the longitudinal direction of the sensor case20. The recess portion24faces in Y direction toward the flow detection body5, and The recess portion24has a bottomed rectangular shape in planar view in Y direction. After other components30,40,50and60are housed in the recess portion24, the potting resin80is filled into the recess portion24.

The reinforced plate30is made of a metal, such as stainless steel. The reinforced plate30is formed as a narrow-width and short thin belt shape in comparison with the sensor case20. The reinforced plate30is positioned and fixed on a bottom surface24aof the recess portion24in a surface contact state. The reinforced plate30is embedded by the potting resin80in the recess portion24.

The sensor substrate40is made of a soft resin, such as polyimide, and is called as flexible printed board. The sensor substrate40is formed as a narrow-width and short shape in comparison with the sensor case20, and the sensor substrate40is formed as a narrow-width and long thin belt shape in comparison with the reinforced plate30. The sensor substrate40is positioned and fixed on a reinforced surface30aof the reinforced plate30on the opposite side of the bottom surface24aof the recess portion24in a surface contact state. The sensor substrate40is embedded by the potting resin80in the recess portion24, and a part40aof the sensor substrate40in Z direction as a longitudinal direction is reinforced by the reinforced plate30. The sensor substrate40is provided with a mounting surface40bin a reinforced part40a, which is formed as a planar surface positioned on the opposite side of the reinforced plate30.

The sensor unit50has a sensor element54which detects humidity representing a ratio of water vapor in the intake air. Humidity is referred to as specified physical quantity relating to the intake air flowing in the intake passage3. The sensor element54of the sensor unit50outputs a humidity signal, referred to as a detection signal in accordance with the humidity of the intake air as a detecting target. The sensor unit50is formed as a rectangular shape as a whole. The sensor unit50is mounted on the mounting surface40bin the reinforced part40aon the sensor substrate40. A part of the sensor unit50in Y direction is embedded by the potting resin80in the recess portion24, and a remaining part of the sensor unit50in Y direction is exposed to the intake passage3positioned outside of the sensor case20.

A plurality of terminals60are provided. Each of the terminals60is made of a metal, such as phosphor bronze. Each of the terminals60is formed as a narrow-width and short thin belt shape in comparison with the sensor case20. Each of the terminals60is disposed substantially in parallel in X direction each other. A part60aof each of the terminals60in Z direction is embedded in the sensor case20toward the connector portion22from the bottom wall24bformed as the bottom surface24aof the recess portion24. Other part60bof each of the terminals60in Z direction is protruded toward outside of the sensor case20from the connector portion22. The other part60bof each of the terminals60is electrically connected to the engine control unit via any one of the terminals in the air flow detection unit22. It is preferable that each of the terminals60is formed as thin having a thickness of 0.2 mm (for example), and is functioned as a low thermal conductivity. So, a heat insulating function is obtained between an outside including the engine control unit, and the circuit module70and the sensor element54such that a detection error due to increasing of a temperature of the sensor element54can be suppressed.

The circuit module70is electrically connected to the sensor element5and each of the terminals60through a metal conductor provided on the sensor substrate40. The circuit module70includes a plurality of circuit elements72for processing a humidity signal outputted from the sensor element54. Each of the circuit elements72is mounted on the mounting surface40bin the reinforced part40aon the sensor substrate40. A control circuit72ain the circuit elements72calculates the humidity of the intake air in the intake passage3based on the humidity signal. The humidity calculated by the control circuit70is sent to the engine control unit by means of the signal through each of the terminals60.

The potting resin80is made of a hard thermoset resin, such as an epoxy resin or a polyurethane, etc. The potting resin80covers almost of the recess portion24. So, the potting resin80covers the mounting surface40bsuch that all circuit elements72on the mounting surface40bare sealed. An electrical short between the circuit elements72and a damage of the circuit elements72are suppressed because the circuit elements72are sealed.

The sensor unit50is explained in detail below.

As shown inFIGS. 6 and 7, the sensor unit50has a sensor body52, a sensor element54, a sensor cover56, and a sensor filter58.

The sensor body52according toFIG. 6is formed of a thermoset resin, such as an epoxy resin, etc. The sensor body52is formed as a rectangular shape having 6 (six) surfaces along each direction of X, Y and Z directions. One surface52bof the sensor body52is positioned and fixed on the mounting surface40bof the sensor substrate40in a surface contact state such that the sensor body52is held on the mounting surface40b.

The sensor body52has a body recess53. As shown inFIGS. 6 and 7, the body recess53is provided at a central portion in X and Z directions. The body recess53opens in the opposite side of the sensor substrate40in Y direction, and is formed as a circle bottomed hole in planar view in Y direction. The body recess53is formed in the opposite surface52aof the sensor body52with respect to the mounting surface40b, and opens at an body opening portion53a. The body recess53according to the first embodiment is formed as a truncated cone hole shape such that a diameter becomes gradually larger toward the body opening portion53afrom a bottom surface53b.

As shown inFIG. 6, the sensor element54senses the humidity of the intake air based on a change of a dielectric constant in a polymer film due to a predetermined correlation with respect to the humidity change of the intake air flowing in the intake passage3. The sensor element54is positioned and fixed on the bottom surface53bseparated from the body opening portion53a, and the sensor element54is housed in the body recess53. The sensor element54is electrically connected to a metal conductor on the sensor substrate40through a metal conductor (not shown) which is embedded on a bottom wall53cforming as the bottom surface53bof the body recess53in the sensor body52. So, the sensor element54is configured to output a humidity signal, which varies electrically based on the sensed humidity to the circuit module70according toFIGS. 4 and 5.

As shown inFIG. 6, the sensor cover56is made of a hard resin, such as PPS or polybutylene terephthalate (PBT), in order to minimize a difference in thermal expansion coefficients with respect to at least the sensor case20and the potting resin80. As shown inFIGS. 6 and 7, the sensor cover56opens in a side of the sensor substrate40in Y direction, and is formed as a bottomed rectangular shape in planar view in Y direction. The sensor cover56includes a cover peripheral portion56bformed as a rectangular tube shape opening at an body opening portion56a, and a bottom wall portion56cformed as a rectangular plate shape closing the cover peripheral portion56bin an opposite side of the body opening portion56ain Y direction. The cover peripheral portion56band the bottom wall portion56care integrally formed.

An inner surface of the cover peripheral portion56bis fitted to the sensor body52along Y direction. The cover peripheral portion56bsurrounds total outer surface of the sensor body52. As shown inFIG. 6, the cover peripheral portion56bhas the body opening portion56ain an opposite side of the bottom wall portion56cin Y direction. A part56dof the cover peripheral portion56bextending from the body opening portion56ato the bottom wall portion56cis positioned and fixed in the potting resin80. The cover peripheral portion56bis provided with an embedded portion56d, which is embedded outside of the sensor body52from the body opening portion56aby the potting resin80.

In order to manufacture the sensor unit50, when the sensor cover56is embedded and fixed in the potting resin80, a thermosetting resin80aas a forming material of the potting resin80fills into the recess portion24in a melting state and is cooled thereafter. Since a load toward the bottom surface24aof the recess portion24and in the arrow direction inFIG. 8continues to act on the sensor cover56, a floating of the sensor cover56due to an inner pressure of the thermosetting resin80ais prevented, and all area of the embedded portion56dis embedded continuously. The thermosetting resin80ais cured on the mounting surface40bof the sensor substrate40, and the embedded portion56dof the cover peripheral portion56bis embedded and fixed in the potting resin80.

Since the thermosetting resin80aheat-shrinks by cooling and curing, a fixing strength of the cover peripheral portion56bby the potting resin80can be enhanced. Since the thermosetting resin80ais entered into a gap between the sensor body52and the cover peripheral portion56bfrom the body opening portion56a, and is cooled and cued thereafter, the fixing strength of the cover peripheral portion56bby the potting resin80can be further enhanced. The embedded portion56dis embedded and fixed in the potting resin80by cooling and curing of the thermosetting resin80a, and a peripheral portion58aof the sensor filter58(later explained) is held between the sensor body52and the bottom wall portion56c.

As shown inFIGS. 6 and 7, the bottom wall portion56cis continuously formed substantially vertical to the cover peripheral portion56bat an opposite side of the body opening portion56ain Y direction. The peripheral portion56afits outside of the sensor body52, and the peripheral portion56ais embedded in the potting resin80. The bottom wall portion56ccovers the sensor body52from the opposite side of the sensor substrate40in Y direction. A part of the intake passage3is formed between an outer surface56gin the opposite side of the bottom wall portion56cwith respect to the sensor body52and the detection portion5aof the flow detection body5according toFIG. 2. As shown inFIG. 6, the outer surface56gof the bottom wall portion56cexposes the intake passage3. An inner surface56eof the bottom wall portion56cin the opposite side of the outer surface56gis separated in Y direction from an opposite surface52aopposite to the mounting surface40bwith respect to the sensor body52.

As shown inFIGS. 6 and 7, a cover window56fis formed as penetrating the bottom wall portion56cat a central portion in X and Z directions. The cover window56ffaces the intake passage3and is separated from the body opening portion53a. The cover window56fis provided between the intake passage3and the body opening portion53a, and penetrates the bottom wall portion56cin Y direction. The cover window56fis formed as a circle penetrating hole shape (cylindrical hole shape) in planar view in Y direction.

As shown inFIG. 6, the sensor filter58is made of a soft resin, such as Polytetrafluoroethylene (PTFE) and is formed as a porous shape. The sensor filter58made of PTFE is excellent in a chemical resistance and a heat resistance such that the sensor filter in a hot intake passage3, in which the intake air including oil flows, hardly deteriorates. Furthermore, a deterioration of a filtering performance is minimized, because a water drop and an oil in the intake air hardly spread in an inside of the sensor filter58.

As shown inFIGS. 6 and 7, the sensor filter58is formed as a flat membrane shape, which is spread along a virtual plane S extending virtually in X and Y directions, and is provided with a filter peripheral part58a. The filter peripheral part58ahas a rectangular contour58aein planar view in Y direction such that the filter peripheral part58ais surrounded by the cover peripheral portion56bfrom outside of the filter peripheral part58a. In the embodiment according toFIGS. 6 and 7, a size of the contour58aeof the filter peripheral part58ais substantially equal to that of an outer contour52cof the sensor body52. Within a range satisfied with a formula 1 (later explained), the size of the contour58aeof the filter peripheral part58amay be smaller than that of an outer contour52cof the sensor body52.

As shown inFIG. 6, one surface58bof the filter peripheral part58ain Y direction comes into surface contact to the opposite surface52aof the sensor body52with respect to the mounting surface40bin a non-joining state. The filter peripheral part58acomes into surface contact to both the sensor body52and the bottom wall portion56csuch that the filter peripheral part58ais held between the sensor body52and the bottom wall portion56c. In an inner peripheral side positioned inwardly with respect to a holding portion in the sensor filter58, one surface58bfaces the intake passage3through the cover window56f, and the opposite surface58cfaces the body opening portion53ain Y direction.

A slight deformation of the sensor filter58held between the sensor body52and the bottom wall portion56cmay be occurred due to a microscopically roughness of each of the sensor body52and the bottom wall portion56ccontacting the filter peripheral part58a. A specification (for example, dimension and material) for the sensor filter58, the sensor body52, and the bottom wall portion56c, is determined in such a manner that the slight deformation is targeted within a permissible range, not hindering a filtering performance of the sensor filter58.

An area in an inner peripheral side positioned inwardly with respect to the contour58aeof the filter peripheral part58ain the projection view in Y direction with respect to the virtual plane S is defined as a filtering area R partitioned by dots hatching area inFIG. 9. Under such definition, in the projection view (namely, a projection view inFIG. 9) in Y direction with respect to the virtual plane S, the cover window56fand the body opening portion53aare positioned in the filtering area R. In the projection view in Y direction with respect to the virtual plane S, the opening portion body53ais positioned in the contour of the cover window56fwithin the filtering area R.

According to the first embodiment, in which an arrangement of each component is explained by utilizing the projection view, the body opening portion53aas a circle contour shape, the cover window56f, and a rectangular contour58aeas the filtering area R are arranged in such a manner that each center of the body opening portion53a, the cover window56f, and the rectangular contour58aeis substantially aligned, as shown inFIG. 10. In the first embodiment, the diameter A of the circle contour of the body opening portion53a, the diameter B of the circle contour of the cover window56f, and the minimum distance C (minimum distance in the radial direction) of the rectangular contour58aeof the filter peripheral part58ain the filtering area R satisfy the following formula 1, as shown inFIG. 10.
A<B<C  (Formula 1)

The sensor filter58filters the intake air flowing into the body recess53through the cover window56fand the body opening portion53afrom the intake passage3. A filtering performance of the sensor filter58can be achieved. When the filtering performance is determined, a presumption in which a carbon1000, which is a foreign particle in the intake air and has a minimum diameter among the foreign particles, is adhered on the sensor filter58and arranged to contact each other on the sensor filter58only with a gap1001, is considered. In such presumption, if for example the minimum diameter ϕc is about 0.003 μm, in the gap1001the maximum diameter of an inscribed circle1002inside three carbons1000is about 0.0046 μm. This figure 0.0046 μm is larger than 0.0004 μm, which designates a minimum diameter of a gap for passing the water vapor in the intake air for the humidity detection. A mesh (namely, gap size for passing the water vapor) of the sensor filter58for determining the filter performance is set to between for example 0.001-0.003 μm such that the water vapor in the intake air can be passed through the gap1001and through the sensor filter58. In consideration with the mesh, the thickness between both of the surfaces58b,58cof the sensor filter58is set to for example, about 0.1 mm.

Effects

The effects in the first embodiment will be explained below.

According to the first embodiment, the sensor body52provided with the body recess53which opens at an body opening portion53a, is covered by the sensor cover56provided with the cover window56fpenetrating between the intake passage3and the body opening portion53a. In such configuration, the sensor filter58is provided with the filter peripheral part58aextending along the virtual plane S. The body opening portion53aand the cover window56fare positioned in the filtering area R positioned on an inner side with respect to the contour58aeof the filter peripheral part58ain the projection view with respect to the virtual plane S. The filter peripheral part58apositions between the sensor body52and the sensor cover56and contacts the sensor body52and the sensor cover56, such that a shape of the sensor filter58extending along the virtual plane S can be maintained and the sensor filter58is prevented to remove from between the sensor body52and the sensor cover56.

According to the first embodiment, the filter peripheral part58aof the sensor filter58, which extending along the virtual plane S, are interposed between the sensor body52and the sensor cover56. Since the filter peripheral part58apositions between the sensor body52and the sensor cover56and contacts the sensor body52and the sensor cover56, the sensor filter58is prevented to remove from between the sensor body52and the sensor cover56.

According to the first embodiment, in the projection view with respect to the virtual plane S, the body opening portion53ais positioned in the cover window56fwithin the filtering area R. The air flowing through the cover window56fand the sensor filter58from the intake passage3introduces into the body recess53from the body opening portion53awithout being blocked by the sensor body52around the body opening portion53a. The air from the intake passage3easily reaches to the sensor element54in the body recess53. Since the sensor filter58extending along the virtual plane S is provided between the sensor body52and the sensor cover56, the sensor filter58is positioned near to the sensor element54in the body recess53. As a result, since an inner volume of the body recess53is small, a time of the air flowing from the intake passage3to the sensor element54can be shortened. Accordingly, since the air easily reaches the sensor element54and the air flowing time to the sensor element54is also minimized, the detection response of the sensor element54can be enhanced.

According to the first embodiment, air including the foreign particle in the intake passage of the internal combustion engine is filtered by the sensor filter58. So, the foreign particle is removed, before the foreign particle reaches the body recess53. The sensor element54in the body recess53is prevented from the damage of the foreign particle directly to the sensor element53. Since the sensor filter53is strongly held between the sensor body52and the sensor cover56, the sensor filter53is prevented to be removed and then to be flowed from the intake passage3to the cylinder in the downstream side.

Second Embodiment

The second embodiment is a modification of the first embodiment.

As shown inFIG. 12, in a sensor filter2058according to the second embodiment, one surface58bof the filter peripheral part58ais connected on the opposite surface52aof the sensor body52with respect to the mounting surface40bin a contacting state by welded or bonded, etc. The filter peripheral part58a, as shown inFIGS. 12 and 13, is provided with a body connecting portion2058don the side of the sensor body52, and the body connecting portion2058dis formed as a continuous circle belt shape having a substantially same width in a planar view in Y direction.

The filter peripheral part58ain the sensor filter2058is provided with an opposite surface58cpositioned in an opposite side of the sensor body52, which surface contacts on the inner surface56eof the bottom wall portion56csuch that the filter peripheral part58ais interposed between the sensor body52and the sensor cover56. In the sensor filter2058connected to the sensor body52, a slight deformation of the filter peripheral part58aheld between the sensor body52and the bottom wall portion56cmay be occurred due to a microscopically roughness of each of the sensor body52and the bottom wall portion56ccontacting the filter peripheral part58a. A specification (for example, dimension and material) for the sensor filter2058, the sensor body52, and the bottom wall portion56cis determined in such a manner that the slight deformation is targeted within a permissible range not hindering a filtering performance of the sensor filter58.

As shown inFIG. 14, under the same definition of the filtering area R in the first embodiment, in the projection view in Y direction with respect to the virtual plane S, the cover window56f, the body opening portion53a, and the body connecting portion2058dare positioned in the filtering area R. In the projection view in Y direction with respect to the virtual plane S, the body connecting portion2058dis positioned outside of the contour of the body opening portion53aand outside of the contour of the cover window56fwithin the filtering area R. Namely, in the projection view in Y direction with respect to the virtual plane S, the body connecting portion2058dis positioned between the rectangular contour58aeof the filter peripheral part58aand the contour of the cover window56f.

According to the second embodiment, the body connecting portion2058das circle belt shape, the body opening portion53aas a circle contour shape, the cover window56f, and a rectangular contour58aeas the filtering area R are arranged in such a manner that each center of the body connecting portion2058d, the body opening portion53a, the cover window56f, and a rectangular contour58aeis substantially aligned, as shown inFIG. 15. In the second embodiment, the diameter D of the inner side of the body connecting portion2058d, the diameter E of the outer side of the body connecting portion2058d, the diameter A of the circle contour of the body opening portion53a, the diameter B of the circle contour of the cover window56f, and the minimum distance C (minimum distance in the radial direction) of the rectangular contour58aeof the filter peripheral part58ain the filtering area R satisfy the following formula 2, as shown inFIG. 15.
A<B<D<E<C  (Formula 2)

According to the second embodiment, the body connecting portion2058din the filter peripheral part58a, connected to the sensor body52, is positioned within the filtering area R in the projection view with respect to the virtual plane S. The filter peripheral part58apositions between the sensor body52and the sensor cover56and contacts the sensor body52and the sensor cover56, such that a shape of the sensor filter2058extending along the virtual plane S can be maintained and the sensor filter58is prevented to remove from between the sensor body52and the sensor cover56. The removal of the sensor filter2058and the deformation of the sensor filter2058are suppressed for a long time. According to the second embodiment, the filter peripheral part58ais joined to the sensor body52at the body connecting portion2058d, and furthermore the filter peripheral part58ais held between the sensor body52and the sensor cover56, such that the removal of the sensor filter2058and the deformation of the sensor filter2058are highly suppressed.

According to the second embodiment, within the filtering area R in the projection view with respect to the virtual plane S, the body opening portion53ais positioned inside of the cover window56f, and the body connecting portion2058dis positioned outside of the cover window56f. A space between the contour of the filter peripheral part58aand the contour of the cover window56fis effectively utilized such that the space for the width of the body connecting portion2058dcan be widened. The joined area at the body connecting portion2058dconnecting the filter peripheral portion58ato the sensor body52can be larger. So, the joined strength between the filter peripheral portion58aand the sensor body52is enhanced and the removal of the sensor filter2058is prevented.

Third Embodiment

The third embodiment is a modification of the second embodiment.

As shown inFIG. 16, the opposite surface58cof the filter peripheral part58ain the opposite side of the sensor unit52is separated from the inner surface56eof the bottom wall portion56cin the sensor cover56with a gap. A cover space portion3059is formed between the filter peripheral part58aand the bottom wall portion56cin Y direction. One surface58bof the filter peripheral part58ais joined to the opposite surface52aof the sensor body52with respect to the mounting surface40bin a surface contacting state.

In the sensor filter3058according to the third embodiment, since the cover space portion3059is formed between the filter peripheral part58aand the sensor cover56, a design freedom, such as measurement or tolerance, etc. is enhanced. A yield rate for manufacturing the sensor unit50is reduced.

Fourth Embodiment

The fourth embodiment is a modification of the first embodiment.

As shown inFIG. 17, in a sensor filter4058according to the fourth embodiment, one surface58cof the filter peripheral part58aopposite to the sensor body52is connected to the inner surface56eof the bottom wall portion56cin the sensor cover56in a surface contacting state by welded or bonded, etc. The filter peripheral part58a, as shown inFIGS. 17 and 18, is provided with a cover connecting portion4058eon the side of the sensor cover56, and the cover connecting portion4058eis formed as a circle belt shape having a substantially same width in a planar view in Y direction.

The filter peripheral part58ain the sensor filter4058is provided with one surface58bsurface-contacts on the opposite surface52aof the sensor body52with respect to the mounting surface40bsuch that the filter peripheral part58ais interposed between the sensor body52and the sensor cover56. In the sensor filter4058connected to the sensor cover56, a slight deformation of the filter peripheral part58aheld between the sensor body52and the bottom wall portion56cmay be occurred due to a microscopically roughness of each of the sensor body52and the bottom wall portion56ccontacting the filter peripheral part58a. A specification (for example, dimension and material) for the sensor filter4058, the sensor body52, and the bottom wall portion56cis determined in such a manner that the slight deformation is targeted within a permissible range not hindering a filtering performance of the sensor filter58.

As shown inFIG. 19, under the same definition of the filtering area R in the first embodiment, in the projection view in Y direction with respect to the virtual plane S, the cover window56f, the body opening portion53a, and the cover connecting portion4058eare positioned within the filtering area R. In the projection view in Y direction with respect to the virtual plane S, the cover connecting portion4058eis positioned outside of the contour of the body opening portion53aand outside of the contour of the cover window56fwithin the filtering area R. Namely, in the projection view in Y direction with respect to the virtual plane S, the cover connecting portion4058eis positioned between the rectangular contour58aeof the filter peripheral part58aand the contour of the cover window56f.

According to the fourth embodiment, the cover connecting portion4058eas circle belt shape, the body opening portion53aas a circle contour shape, the cover window56f, and a rectangular contour58aeas the filtering area R are arranged in such a manner that each center of the cover connecting portion4058e, the body opening portion53a, the cover window56f, and a rectangular contour58aeis substantially aligned, as shown inFIG. 15. In the second embodiment, the diameter F of the inner side of the cover connecting portion4058e, the diameter G of the outer side of the cover connecting portion4058e, the diameter A of the circle contour of the body opening portion53a, the diameter B of the circle contour of the cover window56f, and the minimum distance C (minimum distance in the radial direction) of the rectangular contour58aeof the filter peripheral part58ain the filtering area R satisfy the following formula 3, as shown inFIG. 20.
A<B<F<G<C  (Formula 3)

According to the fourth embodiment, the cover connecting portion4058ein the filter peripheral part58a, connected to the sensor cover56, is positioned within the filtering area R in the projection view with respect to the virtual plane S. The filter peripheral part58apositions between the sensor body52and the sensor cover56and contacts the sensor body52and the sensor cover56, such that a shape of the sensor filter4058extending along the virtual plane S can be maintained and the sensor filter58is prevented to remove from between the sensor body52and the sensor cover56. The removal of the sensor filter2058and the deformation of the sensor filter4058are suppressed for long time. According to the second embodiment, the filter peripheral part58ais joined to the sensor body52at the cover connecting portion4058e, and furthermore the filter peripheral part58ais held between the sensor body52and the sensor cover56, such that the removal of the sensor filter4058and the deformation of the sensor filter4058are highly suppressed.

According to the fourth embodiment, within the filtering area R in the projection view with respect to the virtual plane S, the body opening portion53ais positioned inside of the cover window56f, and the cover connecting portion4058eis positioned outside of the cover window56f. A space between the contour of the filter peripheral part58aand the contour of the cover window56fis effectively utilized such that the space for the width of the cover connecting portion4058ecan be widened. The joined area at the cover connecting portion4058econnecting the filter peripheral portion58ato the sensor body52can be larger. So, the joined strength between the filter peripheral portion58aand the sensor body52is enhanced and the removal of the sensor filter2058is prevented.

Firth Embodiment

The fifth embodiment is a modification of the fourth embodiment.

As shown inFIG. 21, in a sensor filter5058according to the fifth embodiment, one surface58bof the filter peripheral portion58ais separated from the opposite surface52aof the sensor body52with respect to the mounting surface40bwith a gap. A space portion5019is formed in Y direction between the filter peripheral portion58aand the sensor body52. In the sensor filter5058, one surface58cof the filter peripheral part58aopposite to the sensor body52is connected to the inner surface56eof the bottom wall portion56cin the sensor cover56in a surface contacting state in the same manner as in the fourth embodiment.

In the sensor filter5058according to the fifth embodiment, since the space portion5019is formed between the filter peripheral part58aand the sensor body52, a design freedom, such as measurement or tolerance, etc. is enhanced. A yield rate for manufacturing the sensor unit50is reduced.

Sixth Embodiment

The sixth embodiment is a modification of the combination of the second embodiment and the fourth embodiment.

As shown inFIG. 22, a sensor filter according to the sixth embodiment is connected to the sensor body52and the sensor cover56in a surface contacting state by welded or bonded, etc. In the sensor filter6058, the body connecting portion2058din the same manner as in the second embodiment and the cover connecting portion4058ein the same manner as in the fourth embodiment are formed.

Under the same definition of the filtering area R in the first embodiment, a projection view in the same manner as in the second embodiment and a projection view in the same manner as in the fourth embodiment are realized. In the sixth embodiment, as shown inFIG. 23, the diameter D of the inner side of the body connecting portion2058dis substantially same to the diameter F of the inner side of the cover connecting portion4058e. The diameter E of the outer side of the body connecting portion2058dis substantially same to the diameter G of the outer side of the cover connecting portion4058e.

In the sixth embodiment, the body connecting portion2058dconnected between the filter peripheral portion58aand the sensor body52and the cover connecting portion4058econnected between the filter peripheral portion58aand the sensor cover56are positioned within the filtering area R in the projection view with respect to the virtual plane S. In the sensor filter extending along the virtual plane S, the connecting state connecting the filter peripheral portion58awith both the sensor body52and the sensor cover56can be maintained. In the sixth embodiment, the filter peripheral part58ais respectively joined to the sensor body52at the body connecting portion2058dand to the sensor cover56at the cover connecting portion4058e, and furthermore the filter peripheral part58ais held between the sensor body52and the sensor cover56, such that the removal of the sensor filter4058and the deformation of the sensor filter4058are highly suppressed.

Seventh Embodiment

The seventh embodiment is a modification of the first embodiment.

As shown inFIGS. 24 and 25, a sensor cover7056formed as a shape of bottomed cup according to the seventh embodiment, has a through hole7056hin the peripheral portion56b. As shown inFIG. 25, one through hole7056his formed in each wall of four walls of the cover peripheral portion56bformed as the rectangular tube shape. The through hole7056his penetrated in X direction or Z direction, such that the embedded portion56dis formed to be embedded into the through hole7056hby the potting resin80. The through hole7056hpenetrates the embedded portion56dat the position between the body opening portion56aof the cover peripheral portion56band the bottom wall portion56cthereof. The construction of the sensor unit50, which is not explained in the seventh embodiment, may be replaced by each construction among the second embodiment and the sixth embodiment instead of the construction in the first embodiment.

In the seventh embodiment, a thermosetting resin80aas a forming material of the potting resin80, as shown inFIG. 26, fills into each hole through7056h24in a melting state, and fills into the fitting clearance56ibetween the sensor body52and the cover peripheral portion56b, and then is cooled and cured. As shown inFIG. 24, the potting resin80is embedded in each through hole7056hand is formed in the fitting clearance56ibetween the sensor body52and the cover peripheral portion56bfrom the through hole7056h.

In the sensor cover7056formed as a shape of bottomed cup according to the seventh embodiment, the through hole7056hpenetrates the cover peripheral portion56bat the position between the body opening portion56aof the cover peripheral portion56band the bottom wall portion56cthereof. Since the thermosetting resin80aas a forming material of the potting resin80in a melting state fills into the through hole7056h, a floating of the potting resin80with respect to the sensor substrate40is prevented because of an inner pressure of the potting resin80. The sensor cover7056is fixed at a predetermined position by using the potting resin80for covering the circuit elements72, and a position displacement of the sensor filter58provided between the sensor cover7056and the sensor body52is suppressed. In the seventh embodiment which achieves the above mentioned effects, when the thermosetting resin80aembeds into the embedded portion56din a melting state, a load toward the bottom surface24aof the recess portion24may continue to act on the sensor cover56as shown in the first embodiment, or a weight of the sensor cover7056may be utilized as the load toward the bottom surface24aof the recess portion24aas shown inFIG. 24.

Eighth Embodiment

The eighth embodiment is a modification of the first embodiment.

As shown inFIG. 27, the air physical quantity sensor8010according to the eighth embodiment is constructed integrally with the air flow detection unit8002. The air physical quantity sensor8010is provided with the sensor unit50exposed to the second passage8in the bypass passage6, in which a part of the intake air from the intake passage3flows.

The air physical quantity sensor8010includes a sensor case8020shared with the detection portion5aof the flow detection body5, and plural terminals8060shared with plural terminals5bof the flow detection body5. In the air physical quantity sensor8010, the sensor unit50and the circuit module70are mounted on a sensor substrate8040together with the sensor element9aand the circuit module9b. Regarding the quantity relating to the intake air flowing in the bypass passage6, the amount of the flow different from the flow having the humidity detected by the sensor element54of the sensor unit50is detected by another sensor element9amounted on the sensor substrate8040for supporting the sensor body52of the sensor unit50. The sensor filter58of the sensor unit50filters a part of the intake air flowing into the recess portion53through the cover window56fand the body opening portion53afrom the bypass passage6.

Regarding the construction of the sensor unit50, each of the construction thereof according to the second to the seventh embodiments may be applied instead of the construction in the first embodiment. In FIG.27, the illustration regarding each component of the sensor unit50is omitted.

In the eighth embodiment, even if the foreign particle is easily mixed in the intake passage3of the internal combustion1, the foreign particle is prevented from entering in the bypass passage6, according to separation of the intake air from the intake passage3. The sensor element54in the body recess53is prevented the foreign particle from directly hitting the sensor element54, and the removal of the sensor filter2058and the deformation of the sensor filter2058are highly suppressed, and finally the filtering performance is increased.

In the eighth embodiment, another sensor element9afor detecting an air quantity different from the air quantity detected by the sensor elements54, is mounted on the sensor substrate8040, and the sensor body52is supported on the sensor substrate40. The circuit modules70,9bare shared, and the adjustment of the detection value by using the output signal from plural sensor elements54,9ais realized, and the sensor unit50is downsized.

Other Embodiments

The combination of the above mentioned embodiments may be applied, if the combination would be reasonable.

In the modification 1 relating to the first to the eighth embodiments, in the projection view in Y direction with respect to the virtual plane S, the cover window56fis positioned in an inner side with respect to the contour58of the body opening portion53awithin the filtering area R as shown inFIG. 28. In the modification 1 relating to the first, the seventh, and the eighth embodiments, as shown inFIG. 29, the following formula 4 is satisfied. In the modification 1 relating to the second, the third, and the sixth embodiments, as shown inFIG. 30, the following formula 5 is satisfied. In the modification 1 relating to the fourth to the sixth embodiments, as shown inFIG. 31, the following formula 6 is satisfied.FIGS. 28 and 29show the modification 1 relating to the first embodiment,FIG. 30shows the modification 1 relating to the sixth embodiment.
B<A<C  (Formula 4)
B<A<D<E<C  (Formula 5)
B<A<F<G<C  (Formula 6)

In the second modification relating to the second, the third, and the sixth embodiments, in the projection view in Y direction with respect to the virtual plane S, the body connecting portion2058dmay be positioned in an outer side with respect to the contour58of the body opening portion53awithin the filtering area R, as shown inFIG. 31. In the projection view in Y direction with respect to the virtual plane S, the body connecting portion2058dmay be positioned between the contour of the body opening portion53aand the contour of the cover window56f. In the modification 2, as shown inFIG. 32, the following formula 7 is satisfied. In the modification 2, a space between the contour of the body opening portion53aand the contour of the cover window56fis effectively utilized such that the space for the width of the body connecting portion2058dcan be widened. So, the joined strength between the filter peripheral portion58aand the sensor body52is enhanced and the removal of the sensor filters2058,6058is prevented.FIGS. 31, 32show the modification 2 relating to the second embodiment.
A<D<E<B<C  (Formula 7)

In a modification 3 relating to the sixth embodiment, the inner diameter D of the body connecting portion2058dmay be different from the inner diameter F of the cover connecting portion4058e. In a modification 4 relating to the sixth embodiment, the outer diameter E of the body connecting portion2058dmay be different from the outer diameter G of the cover connecting portion4058e.

In a modification 5 relating to the second, the third, and the sixth embodiments, in planar view in Y direction, the body connecting portion2058dmay be formed as, for example, a rectangular belt shape instead of a circle belt shape. In a modification 6 relating to the fourth to the sixth embodiments, in planar view in Y direction, the cover connecting portion5058emay be formed as, for example, a rectangular belt shape instead of a circle belt shape.FIG. 33shows the modification 5 relating to the second embodiment.FIG. 34shows the modification 6 relating to the fourth embodiment.

In a modification 7 relating to the second, the third, and the sixth embodiments, as shown inFIG. 35, a plurality of the body connecting portions2058dmay be provided at a predetermined gap in a circumferential direction on the peripheral portion58a. In a modification 8 relating to the fourth to the sixth embodiments, as shown inFIG. 36, a plurality of the cover connecting portions4058emay be provided at a predetermined gap in a circumferential direction on the peripheral portion58a.FIG. 35shows the modification 7 relating to the second embodiment.FIG. 36shows the modification 8 relating to the fourth embodiment.

In a modification 9 relating to the first to the eighth embodiments, in planar view in Y direction, as shown inFIG. 37, the body opening portion53amay be formed as, for example, a rectangular shape instead of a circle shape. In a modification 10 relating to the first to the eighth embodiments, in planar view in Y direction, as shown inFIG. 37, the cover window56fmay be formed as, for example, a rectangular shape instead of a circle shape. In a modification 11 relating to the first to the eighth embodiments, in planar view in Y direction, as shown inFIG. 38, the contour of the peripheral portion53amay be formed as, for example, a circle shape instead of a rectangular shape.FIG. 37shows the modifications 9, 10 relating to the first embodiment, andFIG. 38shows the modification 11 relating to the first embodiment.

In a modification 12 relating to the first to the eighth embodiments, as shown inFIG. 39, the sensor covers56,7056may be connected to the sensor substrates40,8040at the connecting portion56jby, for example, bonded or welded. In a modification 13 relating to the first to the eighth embodiments, as shown inFIG. 40, the sensor covers56,7056may be connected to the sensor cases20,8020at the connecting portion56kby, for example, bonded or welded. In a modification 14 relating to the first to the eighth embodiments, as shown inFIGS. 41 and 42, the sensor covers56,7056may be positioned and fixed to the sensor cases20,8020by means of a projection-recess fitting through a snap fitting of a claw portion561to the sensor cases20,8020.FIGS. 39 and 40show respectively the modifications 12, 13 relating to the first embodiment, andFIGS. 41 and 42show the modification 14 relating to the first embodiment.

In a modification 15 relating to the seventh embodiment, as shown inFIG. 43, a through hole7056hof the sensor cover7056may be communicated with the body opening portion56aof the cover peripheral portion56b, since an end portion on the opening side of the body opening portion56aconstructed as the embedded portion56dopens. In a modification 16 relating to the first to the eighth embodiments, as shown inFIG. 44, the sensor cover56,7056may be integrally formed with the sensor body52. In a modification 17 relating to the first to the eighth embodiments, as shown inFIG. 42, the sensor cover56,7056may be constructed as a part of the sensor case20,8020.FIGS. 44, 42show the modifications 16, 17 relating to the first embodiment.

In a further modification 18 of the modification 17 relating to the first, the seventh, and the eighth embodiments, as shown inFIG. 45, a first sensor cover56,7056without the cover peripheral portion56band a second sensor cover56,7056having the cover peripheral portion56bmay be provided, and the filter peripheral portion58amay be supported between the first sensor cover56,7056and the second sensor cover56,7056. In the modification 18, the filter peripheral portion58ais held between the first sensor cover56,7056and the second sensor cover56,7056in a contacting state. In the modification 18 relating to the fifth embodiment shown inFIG. 45, a bottom wall portion56cof the second sensor cover56,7056is arranged in a body space portion5059formed between the filter peripheral portion58aand the sensor body52. In the modification 18, the filter peripheral portion58amay be connected to at least one of the first sensor cover56,7056and the second sensor cover56,7056, or may not be connected to the first sensor cover56,7056and the second sensor cover56,7056. In the modification 18 shown inFIG. 45relating to the fourth embodiment, the filter peripheral portion58ais connected to the first sensor cover56,7056such that the cover connecting portion4058eis formed.FIG. 45shows the modification 18 relating to the first embodiment.

In a modification 19 relating to the first to the eight embodiments, the sensor filters58,2058,3058,4058,5058,6058are not only a porous filter made of PTFE but also, for example, a waterproof filter or a air-permeable filter. The filter used in the second to the sixth embodiments may be a fibrous filter made of other material by considering a bonding property. In a modification 20 relating to the first to the eight embodiments, as shown inFIG. 46, the sensor filters58,2058,3058,4058,5058,6058are made from a plurality of filter elements58f, each of which is different from each other as for a material, a roughness, and/or a thickness. In a modification 21 relating to the first to the eight embodiments, as shown inFIG. 47, a reinforcing plate30may be omitted, because the sensor substrate40,8040is made from a hard substrate, such as a glass epoxy substrate instead of the soft flexible substrate.FIGS. 46, 47show respectively the modifications 20, 21 relating to the first embodiment.

In a modification 22 relating to the eighth embodiment, as shown inFIG. 48, another bypass passage8006is configured to separate from the bypass passage6, and the bypass passage8006has an inlet8006aand an outlet8006b, both of which expose the intake passage3. The bypass passage8006is referred to as the flow passage. The sensor unit50may be exposed to the bypass passage8006. In the modification 22, a sensor substrate40, on which the sensor element9aand the circuit module9bare not mounted, is applied as described in the first embodiment.

In a modification 23 relating to the first to the eighth embodiments, as shown inFIG. 49, a hole portion53dpenetrates in Y direction through the sensor body52, and the hole portion53dis covered by the sensor substrate40, on which the sensor element54is mounted. The body recess53may be formed as being surrounded by the hole portion53dand the sensor substrate40. In a modification 24 relating to the first to the eighth embodiments, the sensor element54may detect a specified physical quantity, such as temperature, pressure, thermal conductivity, density, or flow amount for air except for the air humidity. In a modification 25 relating to the first to the eighth embodiments, as shown inFIG. 50, a plurality of the sensor elements54which detect the different physical quantity or detect same physical quantity may be housed in the body recess53.FIGS. 49, 50show respectively the modification 23, 25 relating to the first embodiment.