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JP5182314B2 - Air flow measurement device - Google Patents

Air flow measurement device Download PDF

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Publication number
JP5182314B2
JP5182314B2 JP2010070590A JP2010070590A JP5182314B2 JP 5182314 B2 JP5182314 B2 JP 5182314B2 JP 2010070590 A JP2010070590 A JP 2010070590A JP 2010070590 A JP2010070590 A JP 2010070590A JP 5182314 B2 JP5182314 B2 JP 5182314B2
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cavity
deep groove
air flow
recess
sensor substrate
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JP2010281809A (en
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崇 榎本
順三 山口
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Denso Corp
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Denso Corp
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
    • G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
    • G01F1/692—Thin-film arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6845—Micromachined devices

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)

Description

本発明は、センサ部に薄膜式（チップ式）の流量測定素子を用いた空気流量測定装置に関する。   The present invention relates to an air flow rate measuring apparatus using a thin film type (chip type) flow rate measuring element for a sensor unit.

従来、自動車用エンジンの吸入空気量を測定するエアフロメータ（熱式流量計）には、高精度、高応答の市場要求から、センサ部にチップ式の流量検出素子（以下、センサチップと呼ぶ）を用いたものが知られている（特許文献１参照）。
センサチップは、例えば、図１４（ａ）、（ｂ）に示す様に、センサ基板１００の一部にダイヤフラム（薄膜部）１１０を形成し、そのダイヤフラム１１０の表面上に薄膜抵抗体１２０を配置して構成され、樹脂ケース１３０の表面に形成された凹部１４０に収納されて、接着剤１５０により固定されている。 2. Description of the Related Art Conventionally, air flow meters (thermal flow meters) that measure the intake air amount of automobile engines have a chip-type flow rate detection element (hereinafter referred to as a sensor chip) in the sensor unit because of market requirements with high accuracy and high response. Is known (see Patent Document 1).
For example, as shown in FIGS. 14A and 14B, the sensor chip has a diaphragm (thin film portion) 110 formed on a part of the sensor substrate 100, and a thin film resistor 120 is disposed on the surface of the diaphragm 110. It is comprised, is accommodated in the recessed part 140 formed in the surface of the resin case 130, and is being fixed with the adhesive agent 150. FIG.

しかし、センサ基板１００を樹脂ケース１３０に全面接着すると、両者の線膨張係数が大きく異なるため、センサ基板１００に応力が発生し、その応力によってセンサ基板１００（特に、ダイヤフラム１１０が形成されている部分）に歪みが生じる。その結果、ダイヤフラム１１０の表面上に配置される薄膜抵抗体１２０の抵抗値が変化して、流量検出精度に影響を与えることが分かっている。このため、図１４（ａ）に示す様に、センサ基板１００の長手方向の一方の端部（ダイヤフラム１１０が形成される部分から遠い方の端部）のみを樹脂ケース１３０に接着する片持ち構造が一般的である。 However, when the sensor substrate 100 is entirely bonded to the resin case 130, the linear expansion coefficients of the two differ greatly, so that stress is generated in the sensor substrate 100, and the sensor substrate 100 (particularly, the portion where the diaphragm 110 is formed) due to the stress. ) Is distorted. As a result, it has been found that the resistance value of the thin film resistor 120 arranged on the surface of the diaphragm 110 changes and affects the flow rate detection accuracy. For this reason, as shown in FIG. 14A , the cantilever structure in which only one end in the longitudinal direction of the sensor substrate 100 (the end far from the portion where the diaphragm 110 is formed) is bonded to the resin case 130. Is common.

特開２００８−３０９６２３号公報JP 2008-309623 A

ところが、センサチップを片持ち構造にすると、センサチップの裏側、つまり、樹脂ケース１３０に形成された凹部１４０とセンサ基板１００との間に隙間が生じるため、エアフロメータに空気が流れた時に、センサチップの裏側にも空気が流れる。
しかし、樹脂ケース１３０の凹部１４０とセンサ基板１００との間に生じる隙間は、全体に均一ではなく、センサ基板１００にダイヤフラム１１０が設けられる部分だけ隙間が大きくなっている。つまり、ダイヤフラム１１０は、エッチング等によりセンサ基板１００の裏側に空洞部１１１を設けることで形成されるため、その空洞部１１１の影響によってセンサ基板１００の裏側を通る空気の流れに乱れが生じる。 However, if the sensor chip has a cantilever structure, a gap is formed between the back side of the sensor chip, that is, the recess 140 formed in the resin case 130 and the sensor substrate 100, so that when air flows through the air flow meter, Air also flows behind the chip.
However, the gap formed between the recess 140 of the resin case 130 and the sensor substrate 100 is not uniform as a whole, and the gap is large only in the portion where the diaphragm 110 is provided on the sensor substrate 100. That is, since the diaphragm 110 is formed by providing the cavity 111 on the back side of the sensor substrate 100 by etching or the like, the air flow passing through the back side of the sensor substrate 100 is disturbed by the influence of the cavity 111.

具体的には、図１５（ａ）に示す様に、空洞部１１１の内部にも空気が流れ込むため、センサ基板１００の裏側へ入り込む空気の流量が多くなると、同図（ｂ）、（ｃ）に示す様に、空洞部１１１に渦流が発生し、その渦流の大きさが流量に応じて変化する（当然、流量が多くなる程、渦流も大きくなる）。なお、図１５は、（ａ）、（ｂ）、（ｃ）の順に流量が多くなり、空気の乱れが大きくなる様子を表している。
上記の結果、ダイヤフラム１１０の表面上に配置される薄膜抵抗体１２０（図１４参照）への伝熱が不安定となり、図１６に示す様に、流量が多くなるに連れて特性が変曲するため、エアフロメータの出力が安定せず（出力の時間変動が大きくなる）、また流量と電圧が一義的に決まらないという問題が生じる。
本発明は、上記事情に基づいて成されたもので、その目的は、センサチップの裏側を流れる空気の乱れを抑制することにより、センサ出力を安定化できる空気流量測定装置を提供することにある。 Specifically, as shown in FIG. 15 (a), since the flow of air to the interior of the cavity 111, the flow rate of the air is increased to enter the back side of the sensor substrate 100, and FIG. (B), (c) As shown in FIG. 4, a vortex is generated in the cavity 111, and the magnitude of the vortex changes according to the flow rate (naturally, the vortex increases as the flow rate increases). FIG. 15 shows a state in which the flow rate increases in the order of (a), (b), and (c), and the air turbulence increases.
The above results, the heat transfer to the thin-film resistor 120 disposed on the surface of the diaphragm 110 (see FIG. 14) becomes unstable, as shown in FIG. 16, characteristics inflection As the flow rate increases Therefore, there are problems that the output of the air flow meter is not stabilized (time fluctuation of the output becomes large), and the flow rate and voltage are not uniquely determined.
The present invention has been made based on the above circumstances, and an object of the present invention is to provide an air flow measuring device that can stabilize sensor output by suppressing turbulence of air flowing on the back side of the sensor chip. .

（請求項１の発明）
本発明は、センサ基板の長手方向の一端側に、裏面から表側へ向かってテーパ状に空洞部を形成することにより、この空洞部に対応するセンサ基板の表面にダイヤフラムが設けられ、且つ、このダイヤフラムの表面上に発熱抵抗体を配置したセンサチップと、このセンサチップを保持するために形成された凹部を有し、この凹部に配置されるセンサチップの他端側を接着剤により固定して、センサチップの一端側の裏面および両側面と凹部の底面および両側面との間にそれぞれ隙間を有する状態でセンサチップを片持ち支持するケースとを備え、このケースを空気通路に配置して、発熱抵抗体の熱交換を基に空気流量を測定する空気流量測定装置において、ケースは、センサ基板の長手方向と直交する凹部の幅方向で、センサ基板の裏側を流れる空気流れの上流側に、凹部の底面より深く形成された深溝部を有し、凹部に開口する深溝部の開口幅を深溝開口幅と呼び、センサ基板の裏面に開口する空洞部の開口幅を空洞開口幅と呼ぶ時に、空洞開口幅の上流端角部が深溝開口幅の範囲内に位置し、且つ、深溝開口幅の下流端角部が空洞開口幅の範囲内に位置して、凹部に開口する深溝部の下流側と、センサ基板の裏面に開口する空洞部の上流側とが、凹部の幅方向にオーバラップしていることを特徴とする。 (Invention of Claim 1)
In the present invention, a hollow portion is formed in a tapered shape from one back surface to the front side on one end side in the longitudinal direction of the sensor substrate, so that a diaphragm is provided on the surface of the sensor substrate corresponding to the hollow portion, and this A sensor chip having a heating resistor disposed on the surface of the diaphragm, and a recess formed to hold the sensor chip, and the other end of the sensor chip disposed in the recess is fixed with an adhesive A case where the sensor chip is cantilevered with a gap between the back surface and both side surfaces of the one end side of the sensor chip and the bottom surface and both side surfaces of the recess, and this case is disposed in the air passage, In an air flow rate measuring device that measures the air flow rate based on heat exchange of a heating resistor, the case flows through the back side of the sensor substrate in the width direction of the recess perpendicular to the longitudinal direction of the sensor substrate. That on the upstream side of the air flow, has a deep groove portion which is deeper than the bottom surface of the recess, the opening width of the deep groove portion which opens into the recess called a deep groove opening width, the opening width of the cavity opening to the rear surface of the sensor substrate Is called the cavity opening width, the upstream end corner of the cavity opening width is located within the range of the deep groove opening width, and the downstream end corner of the deep groove opening width is located within the range of the cavity opening width. The downstream side of the deep groove portion that opens to the back surface of the sensor substrate and the upstream side of the hollow portion that opens to the back surface of the sensor substrate overlap in the width direction of the recess .

本発明の空気流量測定装置は、センサチップがケースに片持ち支持されているので、ケースに形成された凹部の底面に接着されていないセンサ基板の一端側では、ケースの凹部とセンサ基板との間に隙間が生じるため、発熱抵抗体を配置したセンサチップの表側だけでなく、センサチップの裏側（ケースの凹部とセンサ基板との間に生じる隙間）にも空気が流れる。
これに対し、請求項１に係る発明の構成では、ケースの表側を流れる空気の一部が、ケースの凹部とセンサ基板との幅方向上流側に形成される隙間に流れ込むと、一旦、凹部の底面より深く形成された深溝部に入り込み、その深溝部からケースの空洞部に向かって流れる。この時、凹部に開口する深溝部の下流側と、センサ基板の裏面に開口する空洞部の上流側とが凹部の幅方向にオーバラップしているので、深溝部から空洞部に向かって流れる空気は、空洞部の上流側に偏る（近寄る）。これにより、テーパ状に形成された空洞部の上流側傾斜面に沿って空気が流れるため、空洞部で渦が出来にくくなり、その結果、センサチップの表側を流れる空気に対し、センサチップの裏側を流れる空気の影響度を相対的に小さくできるので、センサ出力を安定させることが出来る。 In the air flow rate measuring device of the present invention, since the sensor chip is cantilevered by the case, at one end side of the sensor substrate that is not bonded to the bottom surface of the concave portion formed in the case, the concave portion of the case and the sensor substrate are Since a gap is generated between them, air flows not only on the front side of the sensor chip on which the heating resistor is disposed, but also on the back side of the sensor chip (a gap generated between the recess of the case and the sensor substrate).
On the other hand, in the configuration of the invention according to claim 1, once a part of the air flowing on the front side of the case flows into the gap formed on the upstream side in the width direction between the recess of the case and the sensor substrate, It enters the deep groove formed deeper than the bottom surface and flows from the deep groove toward the cavity of the case. At this time, since the downstream side of the deep groove opening in the recess and the upstream side of the cavity opening in the back surface of the sensor substrate overlap in the width direction of the recess , the air flowing from the deep groove toward the cavity Is biased toward (closer to) the upstream side of the cavity. As a result, air flows along the upstream inclined surface of the tapered cavity, so that vortices are difficult to form in the cavity, and as a result, the back of the sensor chip against the air flowing on the front side of the sensor chip. Since the influence of the air flowing through can be made relatively small, the sensor output can be stabilized.

（請求項２に係る発明）
請求項１に記載した空気流量測定装置において、空洞部の最深部でダイヤフラムの上流端に対応する空洞部の内角部を空洞内角部と呼ぶ時に、
センサ基板の幅方向に対して、空洞部の上流端角部と深溝部の下流側角部との間の距離をＬ１、空洞部の上流端角部と空洞内角部との間の距離をＬ２とすると、
Ｌ１≦Ｌ２…………（１）
上記（１）式が成立することを特徴とする。 (Invention according to Claim 2)
In the air flow rate measuring device according to claim 1, when the inner corner of the cavity corresponding to the upstream end of the diaphragm at the deepest portion of the cavity is referred to as a cavity inner corner ,
The distance between the upstream end corner of the cavity and the downstream corner of the deep groove is L1 and the distance between the upstream end of the cavity and the inner corner is L2 with respect to the width direction of the sensor substrate. Then,
L1 ≦ L2 ………… (1)
The above formula (1) is established.

上記（１）式の関係が成立しない場合、つまり、Ｌ１の方がＬ２より大きくなると、凹部の幅方向で、凹部に開口する深溝部の下流側と、センサ基板の裏面に開口する空洞部の上流側とがオーバラップする領域が大きくなる。このため、深溝部から空洞部へ流れ込む空気は、空洞部の上流側傾斜面に沿って流れにくくなる。つまり、空洞部の上流側傾斜面に沿って流れる空気が少なくなり、特に、流量が多く（流速が大きく）なる程、空洞部の上流側傾斜面から離れて流れるため、空洞部に渦が発生し易くなる。
これに対し、上記（１）式の関係が成立すると、凹部に開口する深溝部の下流側と、センサ基板の裏面に開口する空洞部の上流側とがオーバラップする領域は、凹部の幅方向において、空洞部の上流側傾斜面が形成されている範囲内に限定される。これにより、深溝部から空洞部へ流れ込む空気の多くは、空洞部の上流側傾斜面に沿って流れるため、流量が少ない場合は言うまでもなく、流量が多い場合でも、空洞部で渦が出来にくくなる。その結果、センサチップの表側を流れる空気に対し、センサチップの裏側を流れる空気の影響度を相対的に小さくできるので、センサ出力を安定させることが出来る。 When the relationship of the above formula (1) is not established, that is, when L1 is larger than L2, the cavity in the width direction of the concave portion and the downstream portion of the deep groove portion that opens in the concave portion and the hollow portion that opens in the back surface of the sensor substrate . The area where the upstream side overlaps increases. For this reason, the air flowing from the deep groove portion into the cavity portion hardly flows along the upstream inclined surface of the cavity portion. In other words, less air flows along the upstream inclined surface of the cavity, and in particular, the higher the flow rate (the higher the flow velocity), the farther away from the upstream inclined surface of the cavity, the more vortex is generated in the cavity. It becomes easy to do.
On the other hand, when the relationship of the above formula (1) is established, the region where the downstream side of the deep groove portion opening in the recess and the upstream side of the cavity opening in the back surface of the sensor substrate overlap is the width direction of the recess . However, it is limited to the range in which the inclined surface on the upstream side of the cavity is formed. As a result, most of the air flowing into the cavity from the deep groove flows along the inclined surface on the upstream side of the cavity, so it goes without saying that the flow rate is small, and even when the flow rate is high, vortices are difficult to form. . As a result, the influence of the air flowing on the back side of the sensor chip can be made relatively small with respect to the air flowing on the front side of the sensor chip, so that the sensor output can be stabilized.

（請求項３に係る発明）
請求項１または２に記載した空気流量測定装置において、凹部の底面に向かって立ち上がる深溝部の下流側の壁面は、テーパ状に傾斜する空洞部の上流側の傾斜面と同方向に傾斜して設けられていることを特徴とする。
例えば、凹部の底面に向かって立ち上がる深溝部の下流側の壁面が凹部の底面に対し垂直に形成されていると、深溝部から空洞部へ流れ込む空気が空洞部の傾斜面に当たって跳ね返り、その影響で空洞部を流れる空気に乱れを生じる恐れがある。
これに対し、請求項３に係る発明の構成によれば、深溝部から空洞部へ流れ込む空気の流れ方向が空洞部の傾斜面と同方向になるので、深溝部から空洞部へ流れ込んだ空気が空洞部の傾斜面に当たって跳ね返ることが少なくなる。言い換えると、空洞部の傾斜面に沿って流れやすくなるので、空洞部での渦の発生をより少なくできる。 (Invention according to claim 3)
3. The air flow rate measuring device according to claim 1, wherein the wall surface on the downstream side of the deep groove portion that rises toward the bottom surface of the recess is inclined in the same direction as the inclined surface on the upstream side of the tapered cavity portion. It is provided.
For example, if the wall surface on the downstream side of the deep groove that rises toward the bottom surface of the recess is formed perpendicular to the bottom surface of the recess, the air flowing from the deep groove to the cavity hits the inclined surface of the cavity and rebounds. There is a risk of turbulence in the air flowing through the cavity.
On the other hand, according to the configuration of the invention according to claim 3, since the flow direction of the air flowing from the deep groove portion into the cavity portion is the same direction as the inclined surface of the cavity portion, the air flowing from the deep groove portion into the cavity portion is It is less likely to bounce off the inclined surface of the cavity. In other words, since it becomes easy to flow along the inclined surface of the cavity, the generation of vortices in the cavity can be reduced.

（請求項４に係る発明）
請求項１〜３に記載した何れかの空気流量測定装置において、深溝部は、凹部の幅方向と直交する長手方向全体に渡って形成されることを特徴とする。
凹部の底面に深溝部を設ける場合の一例として、上記の様に、凹部の長手方向全体に渡って形成することが出来る。 (Invention of Claim 4)
The air flow rate measuring device according to any one of claims 1 to 3, wherein the deep groove portion is formed over the entire longitudinal direction perpendicular to the width direction of the concave portion.
As an example of a case of providing a deep groove portion on the bottom surface of the recessed portion, as described above, it can be formed over the entire length longitudinal direction of the recess.

（請求項５に係る発明）
請求項１〜３に記載した何れかの空気流量測定装置において、深溝部は、凹部の幅方向と直交する長手方向に対し、センサ基板の裏面に開口する空洞部の開口範囲に渡って形成されることを特徴とする。
凹部の底面に深溝部を設ける場合の一例として、上記の様に、凹部の長手方向に対し、センサ基板の裏面に空洞部が開口している範囲に限定して形成することが出来る。 (Invention according to claim 5)
The air flow rate measuring device according to any one of claims 1 to 3, wherein the deep groove portion is formed over an opening range of a cavity portion opened on the back surface of the sensor substrate with respect to a longitudinal direction orthogonal to the width direction of the concave portion. It is characterized by that.
As an example of a case of providing a deep groove portion on the bottom surface of the recessed portion, as described above, to the long side direction of the recess, can be hollow portion on the back surface of the sensor substrate is formed is limited to a range which is open.

（請求項６に係る発明）
請求項１〜３に記載した何れかの空気流量測定装置において、深溝部は、凹部の幅方向と直交する長手方向に対し、センサ基板の裏面に開口する空洞部の開口幅の両端から、テーパ状に形成された空洞部の傾斜面を延長した方向へテーパ状に拡大して形成されていることを特徴とする。
凹部の底面に深溝部を設ける場合の一例として、上記の様に、凹部の長手方向に対し、センサ基板の裏面に開口する空洞部の開口幅の両端から、テーパ状に形成された空洞部の傾斜面を延長した方向へテーパ状に拡大して形成することが出来る。 (Invention of Claim 6)
4. The air flow rate measuring apparatus according to claim 1, wherein the deep groove portion is tapered from both ends of the opening width of the hollow portion opened on the back surface of the sensor substrate with respect to the longitudinal direction orthogonal to the width direction of the recessed portion. It is characterized in that it is formed in a taper shape in an extending direction of the inclined surface of the hollow portion formed in a shape.
As an example of a case of providing a deep groove portion on the bottom surface of the recessed portion, as described above, to the long side direction of the recess, from both ends of the opening width of the cavity opening to the rear surface of the sensor substrate, a cavity portion formed in a tapered shape The inclined surface can be formed in a taper shape in the extending direction.

（ａ）空気の流れを示すケースとセンサチップの幅方向の断面図、（ｂ）ケースに形成される深溝部とセンサ基板に設けられる空洞部とがオーバラップした状態を説明する断面図である（実施例１）。(A) Cross-sectional view of the case showing the flow of air and the width direction of the sensor chip, (b) Cross-sectional view explaining a state where the deep groove formed in the case and the cavity provided in the sensor substrate overlap. (Example 1). エアフロメータを吸気ダクトに取り付けた状態を示す断面図である。It is sectional drawing which shows the state which attached the air flow meter to the intake duct. （ａ）エアフロメータを上流側から見た正面図、（ｂ）エアフロメータの側面図、（ｃ）エアフロメータを下流側から見た背面図である。(A) The front view which looked at the air flow meter from the upstream side, (b) The side view of an air flow meter, (c) The back view which looked at the air flow meter from the downstream side. （ａ）センサ部による流量計測の原理を説明する温度分布図、（ｂ）センサ部に使用されるセンサチップの断面図である。(A) Temperature distribution diagram illustrating the principle of flow rate measurement by the sensor unit, (b) a cross-sectional view of a sensor chip used in the sensor unit. 上流側温抵抗体の検出温度と下流側温抵抗体の検出温度との温度差ＤＴｈと、空気の流量および流れ方向との相関を示すグラフである。It is a graph which shows the correlation with the temperature difference DTh of the detection temperature of an upstream temperature resistor, and the detection temperature of a downstream temperature resistor, and the flow volume and flow direction of air. 深溝部の変形例を示す断面図である（実施例１）。It is sectional drawing which shows the modification of a deep groove part (Example 1). 深溝部の変形例を示す断面図である（実施例１）。It is sectional drawing which shows the modification of a deep groove part (Example 1). 深溝部の変形例を示す断面図である（実施例１）。It is sectional drawing which shows the modification of a deep groove part (Example 1). 深溝部の変形例を示す断面図である（実施例１）。It is sectional drawing which shows the modification of a deep groove part (Example 1). 深溝部の変形例を示す断面図である（実施例１）。It is sectional drawing which shows the modification of a deep groove part (Example 1). 凹部の長さ方向における深溝部の形状を示す平面図である（実施例１）。(Example 1) which is a top view which shows the shape of the deep groove part in the length direction of a recessed part. 凹部の長さ方向における深溝部の形状を示す平面図である（実施例１）。(Example 1) which is a top view which shows the shape of the deep groove part in the length direction of a recessed part. 凹部の長さ方向における深溝部の形状を示す平面図である（実施例１）。(Example 1) which is a top view which shows the shape of the deep groove part in the length direction of a recessed part. （ａ）長手方向に沿ったケースとセンサチップの断面図、（ｂ）同図（ａ）の幅方向を示すＢ−Ｂ断面図である（従来技術）。(A) It is sectional drawing of a case and a sensor chip along a longitudinal direction, (b) It is BB sectional drawing which shows the width direction of the same figure (a) (prior art). センサ基板に形成された空洞部を流れる空気の状態が流量に応じて変化する様子を示した断面図である。It is sectional drawing which showed a mode that the state of the air which flows through the cavity part formed in the sensor board | substrate changed according to flow volume. 流量に対する出力特性の変化を示すグラフである。It is a graph which shows the change of the output characteristic with respect to flow volume.

本発明を実施するための最良の形態を以下の実施例により詳細に説明する。   The best mode for carrying out the present invention will be described in detail with reference to the following examples.

（実施例１）
この実施例１では、例えば、自動車のエンジンに吸入される空気量を測定するエアフロメータ１に本発明の空気流量測定装置を適用した一例を説明する。
エアフロメータ１は、図２に示す様に、吸気ダクト２に取り付けられるセンサハウジング３と、このセンサハウジング３の内部に組み込まれるセンサ部４とを有する。
吸気ダクト２は、エンジンの吸気ポート（図示せず）に接続される吸気通路の一部を形成するもので、例えば、吸気通路の最上流に配置されるエアクリーナの出口パイプ、あるいは、この出口パイプの下流側に接続される吸気管等である。
センサハウジング３は、図３に示す様に、吸気ダクト２に固定されるフランジ部３ａと、エンジンの運転状態を制御するＥＣＵ（図示せず）との電気的接続を行うコネクタ部３ｂと、吸気ダクト２の内部に挿入される流路形成ボディ３ｃ等が形成されている。 Example 1
In the first embodiment, for example, an example in which the air flow measuring device of the present invention is applied to an air flow meter 1 that measures the amount of air taken into an engine of an automobile will be described.
As shown in FIG. 2, the air flow meter 1 includes a sensor housing 3 attached to the intake duct 2 and a sensor portion 4 incorporated in the sensor housing 3.
The intake duct 2 forms part of an intake passage connected to an intake port (not shown) of the engine. For example, an outlet pipe of an air cleaner arranged at the uppermost stream of the intake passage, or the outlet pipe An intake pipe or the like connected to the downstream side.
As shown in FIG. 3, the sensor housing 3 includes a flange portion 3 a fixed to the intake duct 2, a connector portion 3 b that electrically connects an ECU (not shown) that controls the operating state of the engine, an intake air A flow path forming body 3c and the like inserted into the duct 2 are formed.

流路形成ボディ３ｃには、吸気ダクト２の内部を図２の左側（エアクリーナ側）から右側（エンジン側）に向かって流れる空気、つまり、エンジンが吸入する空気の一部を取り込むバイパス流路５と、このバイパス流路５を流れる空気の一部を取り込むサブバイパス流路６とが形成されている。
バイパス流路５は、空気を取り込む入口５ａから空気を排出する出口５ｂまで略直線的に、且つ、吸気ダクト２を流れる空気の流れ方向と略平行に形成されている。このバイパス流路５は、空気流路の断面形状が円形であり、且つ、バイパス流路５の出口側は、流路断面積が出口５ｂに向かって次第に減少するテーパ状に形成されている。 In the flow path forming body 3c, a bypass flow path 5 for taking in the air flowing from the left side (air cleaner side) to the right side (engine side) in FIG. And a sub-bypass channel 6 for taking in part of the air flowing through the bypass channel 5 is formed.
The bypass flow path 5 is formed substantially linearly from the inlet 5 a that takes in air to the outlet 5 b that discharges air, and substantially parallel to the flow direction of the air flowing through the intake duct 2. The bypass channel 5 has a circular cross-sectional shape of the air channel, and the outlet side of the bypass channel 5 is formed in a tapered shape in which the channel cross-sectional area gradually decreases toward the outlet 5b.

サブバイパス流路６は、バイパス流路５を流れる空気の流れ方向と直交する所定の方向（図２の上下方向）をＹ−Ｙ方向と呼ぶ時に、バイパス流路５に対するＹ−Ｙ方向の一方側（図示上側）にバイパス流路５から分岐するサブバイパス流路６の入口６ａが形成され、バイパス流路５の出口５ｂの周囲に環状の出口６ｂが形成されている。このサブバイパス流路６は、バイパス流路５より流路長が長く、且つ、流路途中で方向が大きく変化する曲がり部を有して形成されている。
また、サブバイパス流路６の入口６ａは、バイパス流路５に対する上流側の入口端部をＡ点、下流側の入口端部をＢ点と呼ぶ時に、バイパス流路５の中心軸からＡ点までの距離より、Ｂ点までの距離の方が大きくなる様に形成されている（図２参照）。つまり、サブバイパス流路６の入口６ａは、上記Ａ点とＢ点とを含む開口面が、バイパス流路５の出口側に傾いて形成されている。 The sub-bypass channel 6 is one of the Y-Y directions with respect to the bypass channel 5 when a predetermined direction (vertical direction in FIG. 2) orthogonal to the flow direction of the air flowing through the bypass channel 5 is called a Y-Y direction. An inlet 6 a of the sub bypass channel 6 that branches from the bypass channel 5 is formed on the side (the upper side in the drawing), and an annular outlet 6 b is formed around the outlet 5 b of the bypass channel 5. The sub-bypass channel 6 has a longer channel length than the bypass channel 5 and is formed with a bent portion whose direction changes greatly in the middle of the channel.
In addition, the inlet 6a of the sub-bypass channel 6 has a point A from the central axis of the bypass channel 5 when the upstream inlet end with respect to the bypass channel 5 is referred to as point A and the downstream inlet end is referred to as point B. It is formed so that the distance to point B is larger than the distance to (see FIG. 2). In other words, the inlet 6 a of the sub-bypass channel 6 is formed such that the opening surface including the points A and B is inclined toward the outlet side of the bypass channel 5.

センサ部４は、図４（ｂ）に示す様に、例えば、シリコン製のセンサ基板７に設けられるダイヤフラム８の表面上に薄膜抵抗体（発熱抵抗体９と側温抵抗体１０、１１）を形成したセンサチップ１２と、発熱抵抗体９の発熱温度を制御すると共に、側温抵抗体１０、１１の抵抗値を基に、空気の流量と流れ方向に応じたセンサ信号を出力する回路部（図示せず）とを備え、センサチップ１２がケース１３に保持されてサブバイパス流路６の曲がり部に配置されている。
発熱抵抗体９は、サブバイパス流路６を流れる空気の温度よりも一定温度高い基準温度に通電制御される。側温抵抗体１０、１１は、発熱抵抗体９の上流側に近接して配置される一方の側温抵抗体（以下、上流側温抵抗体１０と呼ぶ）と、発熱抵抗体９の下流側に近接して配置される他方の側温抵抗体（以下、下流側温抵抗体１１と呼ぶ）である。 As shown in FIG. 4B, the sensor unit 4 includes, for example, a thin film resistor (a heating resistor 9 and side temperature resistors 10, 11) on the surface of a diaphragm 8 provided on a silicon sensor substrate 7. A circuit unit that controls the heat generation temperature of the formed sensor chip 12 and the heat generation resistor 9, and outputs a sensor signal corresponding to the flow rate and flow direction of air based on the resistance values of the side temperature resistors 10 and 11. (Not shown), and the sensor chip 12 is held by the case 13 and arranged at the bent portion of the sub-bypass channel 6.
The heating resistor 9 is energized and controlled to a reference temperature that is higher than the temperature of the air flowing through the sub-bypass passage 6 by a certain temperature. The side temperature resistors 10 and 11 are one side temperature resistor (hereinafter referred to as the upstream temperature resistor 10) disposed close to the upstream side of the heating resistor 9 and the downstream side of the heating resistor 9. Is the other side temperature resistor (hereinafter, referred to as the downstream temperature resistor 11) disposed in the vicinity.

ここで、センサ部４による空気流量の計測原理について説明する。
発熱抵抗体９が基準温度に通電制御されると、発熱抵抗体９の発熱による温度分布が生じる。ここで、サブバイパス流路６に空気の流れが発生していない時は、図４（ａ）に破線グラフで示す様に、発熱抵抗体９の位置を中心として上流側と下流側とで温度分布が左右対称となるため、上流側温抵抗体１０で検出される温度と、下流側温抵抗体１１で検出される温度とが等しくなる。
これに対し、例えば、サブバイパス流路６に順流方向の空気流が生じると、図４（ａ）に実線グラフで示す様に、発熱抵抗体９の下流側（図示右側）へ片寄った温度分布が生じることで、上流側温抵抗体１０の検出温度より下流側温抵抗体１１の検出温度の方が高くなる。 Here, the measurement principle of the air flow rate by the sensor unit 4 will be described.
When the heating resistor 9 is energized and controlled to the reference temperature, a temperature distribution due to heat generated by the heating resistor 9 occurs. Here, when there is no air flow in the sub-bypass channel 6, as shown by the broken line graph in FIG. 4 (a), the temperature is increased between the upstream side and the downstream side around the position of the heating resistor 9. Since the distribution is symmetrical, the temperature detected by the upstream temperature resistor 10 is equal to the temperature detected by the downstream temperature resistor 11.
On the other hand, for example, when a forward air flow is generated in the sub-bypass channel 6, as shown by a solid line graph in FIG. 4A, the temperature distribution is shifted to the downstream side (the right side in the drawing) of the heating resistor 9. As a result, the detected temperature of the downstream temperature resistor 11 becomes higher than the detected temperature of the upstream temperature resistor 10.

一方、サブバイパス流路６に逆流方向の空気流が生じると、発熱抵抗体９の上流側（図示左側）へ片寄った温度分布が生じることで、下流側温抵抗体１１の検出温度より上流側温抵抗体１０の検出温度の方が高くなる。
上記の様に、上流側温抵抗体１０の検出温度と下流側温抵抗体１１の検出温度との間に温度差ＤＴｈが生じると、この温度差ＤＴｈに応じて、上流側温抵抗体１０と下流側温抵抗体１１の抵抗値がそれぞれ変化するため、この抵抗値の変化により生じる電位差が増幅されて、センサ信号（例えばアナログ電圧）としてＥＣＵへ出力される。なお、センサ信号は、アナログ電圧を周波数値に変換して出力することも出来る。図５は、上流側温抵抗体１０の検出温度と下流側温抵抗体１１の検出温度との温度差ＤＴｈと、空気の流量および流れ方向との相関を示すグラフである。 On the other hand, when an air flow in the reverse flow direction is generated in the sub-bypass channel 6, a temperature distribution that is shifted toward the upstream side (the left side in the drawing) of the heating resistor 9 is generated, so that the upstream side of the detected temperature of the downstream temperature resistor 11. The detected temperature of the temperature resistor 10 is higher.
As described above, when a temperature difference DTh occurs between the detected temperature of the upstream temperature resistor 10 and the detected temperature of the downstream temperature resistor 11, the upstream temperature resistor 10 and the temperature difference DTh are determined according to the temperature difference DTh. Since the resistance value of the downstream temperature resistor 11 changes, the potential difference caused by the change in the resistance value is amplified and output to the ECU as a sensor signal (for example, an analog voltage). The sensor signal can also be output by converting an analog voltage into a frequency value. FIG. 5 is a graph showing the correlation between the temperature difference DTh between the detected temperature of the upstream temperature resistor 10 and the detected temperature of the downstream temperature resistor 11, and the flow rate and flow direction of air.

次に、本発明に係るセンサチップ１２とケース１３について説明する。
センサチップ１２は、センサ基板７の長手方向（図１の紙面と垂直方向）の一端側にダイヤフラム８が形成されている。
このダイヤフラム８は、図４（ｂ）に示す様に、センサ基板７の表面にスパッタ法あるいはＣＶＤ法等により形成される絶縁膜であり、例えば、異方性エッチングにより、センサ基板７の裏面から絶縁膜との境界面までセンサ基板７の一部を除去して、センサ基板７に空洞部７ａを形成することにより設けられる。
なお、空洞部７ａは、センサ基板７の長手方向、および、図１（ａ）に示す幅方向ともに、センサ基板７の裏面から表側へ向かって、空洞部７ａの開口幅が次第に小さくなるテーパ状に形成されている。 Next, the sensor chip 12 and the case 13 according to the present invention will be described.
Sensor chip 12, the diaphragm 8 is formed on one end side in the longitudinal direction of the sensor substrate 7 (the direction perpendicular to the plane of FIG. 1).
As shown in FIG. 4B, the diaphragm 8 is an insulating film formed on the surface of the sensor substrate 7 by a sputtering method or a CVD method. For example, the diaphragm 8 is formed from the back surface of the sensor substrate 7 by anisotropic etching. The sensor substrate 7 is provided by removing a part of the sensor substrate 7 up to the boundary surface with the insulating film and forming a cavity 7 a in the sensor substrate 7.
Incidentally, the hollow portion 7a in the longitudinal direction of the sensor substrate 7, and, in the width direction both shown in FIG. 1 (a), towards the rear surface of the sensor substrate 7 to the front side, the opening width of the cavity portion 7a is gradually reduced tapered It is formed in a shape.

ケース１３は、例えば、樹脂製であり、図１（ａ）に示す様に、空気の流れに沿った表面に凹部１３ａが形成され、この凹部１３ａにセンサチップ１２を配置して、センサ基板７の他端側を接着剤（図示せず）により凹部１３ａの底面に固定することでセンサチップ１２を片持ち支持している。つまり、ダイヤフラム８が形成されるセンサ基板７の一端側は、凹部１３ａの底面に接着されていないため、センサ基板７の裏面および両側面と、凹部１３ａの底面および両側面との間にそれぞれ隙間を有している。なお、ケース１３は、樹脂製に限定されるものではないが、本実施例では、樹脂製であることが望ましい。 Case 13, for example, made of resin, as shown in FIG. 1 (a), recesses 13a are formed on the surface along the flow of air, by placing the sensor chip 12 in the recess 13a, the sensor substrate 7 The other end side of the sensor chip 12 is fixed to the bottom surface of the recess 13a with an adhesive (not shown) to support the sensor chip 12 in a cantilever manner. That is, since one end side of the sensor substrate 7 on which the diaphragm 8 is formed is not bonded to the bottom surface of the recess 13a, there is a gap between the back surface and both side surfaces of the sensor substrate 7 and the bottom surface and both side surfaces of the recess 13a. the has. Contact name casing 13 is not limited to resin, in the present embodiment, it is desirable that the resin.

また、ケース１３は、図１（ａ）に示す様に、センサ基板７の長手方向と直交する凹部１３ａの幅方向（図示左右方向）で、センサ基板７の裏側を流れる空気流れの上流側（図示左側）に、凹部１３ａの底面より深く形成された深溝部１４を有している。
ここで、凹部１３ａの幅方向で、凹部１３ａに開口する深溝部１４の開口幅を深溝開口幅と呼び、センサ基板７の裏面に開口する空洞部７ａの開口幅を空洞開口幅と呼ぶ時に、図１（ｂ）に示す様に、空洞開口幅の上流端角部（図中Ｘ点）が深溝開口幅の範囲内に位置し、且つ、深溝開口幅の下流端角部（図中Ｚ点）が空洞開口幅の範囲内に位置している。すなわち、凹部に開口する深溝部１４の下流側と、センサ基板７の裏面に開口する空洞部７ａの上流側とが凹部１３ａの幅方向にオーバラップしている。
但し、深溝部１４の下流側と空洞部７ａの上流側とがオーバラップする範囲は、図１（ｂ）に示すＸ点とＺ点との幅方向の距離が、Ｘ点とＹ点との幅方向の距離以下であることが望ましい。 In addition, as shown in FIG. 1A, the case 13 has an upstream side of the air flow that flows through the back side of the sensor substrate 7 in the width direction of the recess 13a perpendicular to the longitudinal direction of the sensor substrate 7 (in the horizontal direction in the drawing). On the left side in the figure, there is a deep groove portion 14 formed deeper than the bottom surface of the recess 13a .
Here, in the width direction of the concave portion 13a, the opening width of the deep groove portion 14 opening in the concave portion 13a is referred to as a deep groove opening width, and the opening width of the hollow portion 7a opening in the back surface of the sensor substrate 7 is referred to as a hollow opening width. As shown in FIG. 1 (b), the upstream end corner (point X in the figure) of the cavity opening width is located within the range of the deep groove opening width, and the downstream end corner (point Z in the figure) of the deep groove opening width. ) Is located within the cavity opening width. That is, the downstream side of the deep groove portion 14 opening in the recess and the upstream side of the cavity portion 7a opening in the back surface of the sensor substrate 7 overlap in the width direction of the recess 13a .
However, the range in which the downstream side of the deep groove portion 14 and the upstream side of the cavity portion 7a overlap is such that the distance in the width direction between the point X and the point Z shown in FIG. It is desirable that the distance is equal to or less than the distance in the width direction.

具体的に説明すると、図１（ｂ）に示すセンサ基板７の幅方向（図示左右方向）で、空洞部７ａの最深部でダイヤフラム８の上流端に対応する空洞部７ａの内角部を空洞内角部（図中Ｙ点）と呼ぶ時に、凹部１３ａの幅方向に対して、上記した空洞部７ａの上流端角部（図中Ｘ点）と深溝部１４の下流側角部（図中Ｚ点）との間の距離をＬ１、空洞部７ａの上流端角部（図中Ｘ点）と空洞内角部（図中Ｙ点）との間の距離をＬ２とすると、
Ｌ１≦Ｌ２…………（１）
上記（１）式が成立していることが良い。 Cavity Specifically, in the width direction of the sensor substrate 7 shown in FIG. 1 (b) (shown left and right directions), the internal angle of the cavity portion 7a corresponding to the upstream end of the diaphragm 8 in the deepest portion of the air-dong portion 7a sometimes referred to as the interior angle portion (in the drawing Y point), with respect to the width direction of the recess 13 a, the upstream end corners of the cavity portion 7a described above downstream corner of the (in the drawing X point) and deep groove portion 14 (in the figure L1 is the distance between the Z-point) and L2 is the distance between the upstream end corner (point X in the figure) and the cavity inner corner (point Y in the figure) of the cavity 7a.
L1 ≦ L2 ………… (1)
The above equation (1) is preferably satisfied.

上記の構成によれば、ケース１３の表側を流れる空気の一部が、ケース１３の凹部１３ａとセンサ基板７との上流側に形成される隙間に流れ込むと、一旦、凹部１３ａの底面より深く形成された深溝部１４に入り込み、その深溝部１４からケース１３の空洞部７ａに向かって流れる。この時、凹部１３ａに開口する深溝部１４の下流側と、センサ基板７の裏面に開口する空洞部７ａの上流側とが凹部１３ａの幅方向にオーバラップしているので、深溝部１４から空洞部７ａに向かって流れる空気は、空洞部７ａの上流側に偏る（近寄る）。特に、上記（１）式が成立する構成であれば、深溝部１４と空洞部７ａとがオーバラップする領域は、センサ基板７の幅方向において、空洞部７ａの上流側の傾斜面が形成されている範囲内に限定される。 According to the above configuration, when a part of the air flowing on the front side of the case 13 flows into the gap formed on the upstream side of the concave portion 13a of the case 13 and the sensor substrate 7, it is once formed deeper than the bottom surface of the concave portion 13a. It enters the deep groove portion 14 , and flows from the deep groove portion 14 toward the cavity portion 7 a of the case 13. At this time, the downstream side of the deep groove portion 14 opening to the recess 13a, since the upstream side of the cavity portion 7a that opens to the rear surface of the sensor substrate 7 are overlapped in the width direction of the recess 13a, the cavity from the deep groove portion 14 The air flowing toward the portion 7a is biased (approached) to the upstream side of the cavity portion 7a. In particular, if the above formula (1) is satisfied, the region where the deep groove portion 14 and the cavity portion 7a overlap is formed with an inclined surface on the upstream side of the cavity portion 7a in the width direction of the sensor substrate 7. It is limited within the range.

これにより、深溝部１４から空洞部７ａへ流れ込む空気の多くは、図１（ａ）に空気の流れを示す実線矢印の様に、空洞部７ａの上流側の傾斜面に沿って流れるため、流量が少ない場合は言うまでもなく、流量が多い場合でも、空洞部７ａで渦が出来にくくなる。その結果、センサチップ１２の表側を流れる空気に対し、センサチップ１２の裏側を流れる空気の影響度を相対的に小さくできるので、特性が変曲することはなく、センサ出力を安定させることが出来る。
なお、本発明に係る深溝部１４の形状は、図１に示した形状に限定されるものではなく、深溝部１４から空洞部７ａへ流れ込む空気が、空洞部７ａの上流側の傾斜面に沿って流れることが出来る形状であれば良い。 As a result, most of the air flowing from the deep groove portion 14 into the cavity portion 7a flows along the inclined surface on the upstream side of the cavity portion 7a as indicated by the solid arrow indicating the air flow in FIG. Needless to say, when the flow rate is small, even when the flow rate is large, it becomes difficult to form a vortex in the hollow portion 7a. As a result, the influence of the air flowing on the back side of the sensor chip 12 can be made relatively small with respect to the air flowing on the front side of the sensor chip 12, so that the characteristics do not change and the sensor output can be stabilized. .
In addition, the shape of the deep groove part 14 which concerns on this invention is not limited to the shape shown in FIG. 1 , The air which flows into the cavity part 7a from the deep groove part 14 follows the inclined surface of the upstream of the cavity part 7a. Any shape can be used as long as it can flow.

例えば、図６〜図１０に示す形状が考えられる。
図６に示す深溝部１４は、凹部１３ａの底面に向かって立ち上がる深溝部１４の下流側の壁面１４ａが、テーパ状に傾斜する空洞部７ａの上流側の傾斜面と同方向に傾斜している一例である。
図７に示す深溝部１４は、凹部１３ａの底面に向かって立ち上がる下流側の壁面を階段状に設けた一例である。つまり、深溝部１４の下流側が、最深部から凹部１３ａの底面に至るまで段階的に浅くなる様に形成されている。
図８に示す深溝部１４は、図７に示す深溝部１４の形状とは逆に、上流側の壁面が段階的に深くなる様に、階段状に設けた一例である。 For example, the shapes shown in FIGS .
In the deep groove portion 14 shown in FIG. 6 , the wall surface 14a on the downstream side of the deep groove portion 14 rising toward the bottom surface of the concave portion 13a is inclined in the same direction as the inclined surface on the upstream side of the cavity portion 7a inclined in a tapered shape. It is an example.
The deep groove portion 14 shown in FIG. 7 is an example in which a downstream wall surface that rises toward the bottom surface of the recess 13a is provided in a staircase pattern. That is, the downstream side of the deep groove portion 14 is formed so as to be gradually reduced from the deepest portion to the bottom surface of the concave portion 13a.
Deep groove portion 14 shown in FIG. 8, as opposed to the shape of the deep groove portion 14 shown in FIG. 7, as the wall surface of the upstream side becomes gradually deeper, an example provided stepwise.

図９に示す深溝部１４は、楔形状に設けた一例である。つまり、深溝部１４の上流端と下流端との間に深溝部１４の最深部を形成し、この最深部に向かって、深溝部１４の上流側および下流側の両壁面が傾斜して設けられている。
図１０に示す深溝部１４は、最深部をＲ形状に設けた一例である。特に、図９に示した楔形状との違いは、深溝部１４の上流側の壁面が直線状ではなく、Ｒ形状の最深部まで緩やかに湾曲（凹曲）していることである。
上記の図６〜図１０は、いずれも、凹部１３ａの底面に向かって立ち上がる深溝部１４の下流側の壁面が、テーパ状に傾斜する空洞部７ａの上流側の傾斜面と同方向に傾斜しているので、深溝部１４から空洞部７ａへ流れ込んだ空気が、空洞部７ａの傾斜面に沿って流れやすくなり、空洞部７ａでの渦の発生をより少なくできる。 The deep groove portion 14 shown in FIG. 9 is an example provided in a wedge shape. In other words, the deepest portion of the deep groove portion 14 is formed between the upstream and downstream ends of the deep groove portion 14, toward the deepest portion, the both wall surfaces of the upstream and downstream of the deep groove portion 14 provided obliquely ing.
The deep groove portion 14 shown in FIG. 10 is an example in which the deepest portion is provided in an R shape. In particular, the difference from the wedge shape shown in FIG. 9 is that the upstream wall surface of the deep groove portion 14 is not linear but gently curved (concave) to the deepest portion of the R shape.
6 to 10 described above, the wall surface on the downstream side of the deep groove portion 14 rising toward the bottom surface of the recess 13a is inclined in the same direction as the inclined surface on the upstream side of the cavity portion 7a inclined in a tapered shape. Therefore, the air flowing from the deep groove portion 14 into the cavity portion 7a can easily flow along the inclined surface of the cavity portion 7a, and the generation of vortices in the cavity portion 7a can be reduced.

なお、図６〜図１０に例示した深溝部１４は、凹部１３ａの幅方向に沿った断面形状を示しているが、凹部１３ａの幅方向と直交する長手方向においても、幾つかの異なる形状を採用することができる。
例えば、図１１に示す深溝部１４は、凹部１３ａの長手方向（図示上下方向）全体に渡って形成した一例である。
図１２に示す深溝部１４は、凹部１３ａの長手方向に対し、センサ基板７の裏面に開口する空洞部７ａに対応して形成した一例である。センサ基板７の長手方向における空洞部７ａの開口寸法と略同一の大きさ（長さ）に形成されている。
図１３に示す深溝部１４は、凹部１３ａの長手方向に対し、センサ基板７の裏面に開口する空洞部７ａの開口幅の両端から、テーパ状に形成された空洞部７ａの傾斜面を延長した方向へテーパ状に拡大して形成されている一例である。 The deep groove portion 14 illustrated in FIGS. 6 to 10 shows a cross-sectional shape along the width direction of the recess portion 13a, but also has several different shapes in the longitudinal direction perpendicular to the width direction of the recess portion 13a. Can be adopted.
For example, the deep groove portion 14 shown in FIG. 11 is an example formed over the entire longitudinal direction (the vertical direction in the drawing) of the concave portion 13a.
The deep groove part 14 shown in FIG. 12 is an example formed corresponding to the cavity part 7a opened in the back surface of the sensor substrate 7 with respect to the longitudinal direction of the concave part 13a. The sensor substrate 7 is formed to have substantially the same size (length) as the opening dimension of the cavity 7 a in the longitudinal direction.
The deep groove portion 14 shown in FIG. 13 extends the inclined surface of the cavity portion 7a formed in a tapered shape from both ends of the opening width of the cavity portion 7a opening on the back surface of the sensor substrate 7 with respect to the longitudinal direction of the recess portion 13a. It is an example formed by expanding in a taper shape in the direction.

１ エアフロメータ（空気流量測定装置）
２ 吸気ダクト（空気通路） ７ センサ基板
７ａ センサ基板の空洞部
８ ダイヤフラム
９ 発熱抵抗体
１２ センサチップ
１３ ケース
１３ａ ケースに形成された凹部
１４ 深溝部
Ｘ 空洞部の上流端角部
Ｙ 空洞内角部
Ｚ 深溝部の下流側角部 1 Air flow meter (air flow measuring device)
2 Intake duct (air passage) 7 Sensor substrate 7a Sensor substrate cavity 8 Diaphragm 9 Heating resistor 12 Sensor chip 13 Case 13a Concave portion formed in the case
14 deep groove part X upstream end corner of the cavity Y inner corner of the cavity Z downstream corner of the deep groove

Claims (6)

センサ基板の長手方向の一端側に、裏面から表側へ向かってテーパ状に空洞部を形成することにより、この空洞部に対応する前記センサ基板の表面にダイヤフラムが設けられ、且つ、このダイヤフラムの表面上に発熱抵抗体を配置したセンサチップと、
このセンサチップを保持するために形成された凹部を有し、この凹部に配置される前記センサチップの他端側を接着剤により固定して、前記センサチップの一端側の裏面および両側面と前記凹部の底面および両側面との間にそれぞれ隙間を有する状態で前記センサチップを片持ち支持するケースとを備え、
このケースを空気通路に配置して、前記発熱抵抗体の熱交換を基に空気流量を測定する空気流量測定装置において、
前記ケースは、前記センサ基板の長手方向と直交する前記凹部の幅方向で、前記センサ基板の裏側を流れる空気流れの上流側に、前記凹部の底面より深く形成された深溝部を有し、前記凹部に開口する前記深溝部の開口幅を深溝開口幅と呼び、前記センサ基板の裏面に開口する前記空洞部の開口幅を空洞開口幅と呼ぶ時に、
前記空洞開口幅の上流端角部が前記深溝開口幅の範囲内に位置し、且つ、前記深溝開口幅の下流端角部が前記空洞開口幅の範囲内に位置して、前記凹部に開口する前記深溝部の下流側と、前記センサ基板の裏面に開口する前記空洞部の上流側とが、前記凹部の幅方向にオーバラップしていることを特徴とする空気流量測定装置。 By forming a hollow portion in a tapered shape from one back surface to the front side on one end side in the longitudinal direction of the sensor substrate, a diaphragm is provided on the surface of the sensor substrate corresponding to the hollow portion, and the surface of the diaphragm A sensor chip having a heating resistor disposed thereon;
The sensor chip has a recess formed to hold the sensor chip, and the other end side of the sensor chip disposed in the recess is fixed with an adhesive, and the back surface and both side surfaces of the sensor chip on one end side and the A case for supporting the sensor chip in a cantilevered manner with a gap between the bottom surface and both side surfaces of the recess,
In the air flow rate measuring device that arranges this case in the air passage and measures the air flow rate based on the heat exchange of the heating resistor,
The case is in the width direction of the recess perpendicular to the longitudinal direction of the sensor substrate, on the upstream side of the air flow through the back side of the sensor substrate includes a deep groove portion deeply formed from the bottom of the recess, the When the opening width of the deep groove opening in the recess is referred to as a deep groove opening width and the opening width of the cavity opening in the back surface of the sensor substrate is referred to as a cavity opening width,
An upstream end corner of the cavity opening width is positioned within the range of the deep groove opening width, and a downstream end corner of the deep groove opening width is positioned within the range of the cavity opening width and opens into the recess. and a downstream side of the deep groove portion, and the upstream side of the cavity opening to the rear surface of the sensor substrate, air flow rate measuring device which is characterized in that overlap in the width direction of the recess. 請求項１に記載した空気流量測定装置において、
前記空洞部の最深部で前記ダイヤフラムの上流端に対応する前記空洞部の内角部を空洞内角部と呼ぶ時に、
前記ケースの幅方向に対して、前記空洞部の前記上流端角部と前記深溝部の前記下流側角部との間の距離をＬ１、前記空洞部の前記上流端角部と前記空洞内角部との間の距離をＬ２とすると、
Ｌ１≦Ｌ２…………（１）
上記（１）式が成立することを特徴とする空気流量測定装置。 In the air flow rate measuring device according to claim 1,
The interior angle portion of the cavity corresponding to the upstream end of the diaphragm in the deepest portion of the front Symbol cavity when called a hollow inner angle portion,
The distance between the upstream end corner of the cavity and the downstream corner of the deep groove is L1 with respect to the width direction of the case , and the upstream end corner of the cavity and the inner corner of the cavity Let L2 be the distance between
L1 ≦ L2 ………… (1)
An air flow rate measuring device characterized in that the above equation (1) is established. 請求項１または２に記載した空気流量測定装置において、
前記凹部の底面に向かって立ち上がる前記深溝部の下流側の壁面は、テーパ状に傾斜する前記空洞部の上流側の傾斜面と同方向に傾斜して設けられていることを特徴とする空気流量測定装置。 In the air flow rate measuring device according to claim 1 or 2,
An air flow rate characterized in that the downstream wall surface of the deep groove portion rising toward the bottom surface of the recess is inclined in the same direction as the upstream inclined surface of the hollow portion inclined in a tapered shape. measuring device. 請求項１〜３に記載した何れかの空気流量測定装置において、
前記深溝部は、前記凹部の幅方向と直交する長手方向全体に渡って形成されることを特徴とする空気流量測定装置。 In any one of air flow measuring devices given in claims 1-3,
The deep groove portion is formed over the entire longitudinal direction perpendicular to the width direction of the concave portion. 請求項１〜３に記載した何れかの空気流量測定装置において、
前記深溝部は、前記凹部の幅方向と直交する長手方向に対し、前記センサ基板の裏面に開口する前記空洞部の開口範囲に渡って形成されることを特徴とする空気流量測定装置。 In any one of air flow measuring devices given in claims 1-3,
The said deep groove part is formed over the opening range of the said cavity part opened to the back surface of the said sensor board | substrate with respect to the longitudinal direction orthogonal to the width direction of the said recessed part . 請求項１〜３に記載した何れかの空気流量測定装置において、
前記深溝部は、前記凹部の幅方向と直交する長手方向に対し、前記センサ基板の裏面に開口する前記空洞部の開口幅の両端から、テーパ状に形成された前記空洞部の傾斜面を延長した方向へテーパ状に拡大して形成されていることを特徴とする空気流量測定装置。 In any one of air flow measuring devices given in claims 1-3,
The deep groove portion extends from the both ends of the opening width of the cavity portion opened on the back surface of the sensor substrate with respect to the longitudinal direction perpendicular to the width direction of the recess portion, and the inclined surface of the cavity portion formed in a tapered shape is extended. The air flow rate measuring device is formed to expand in a tapered shape in the direction.
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