JP2006010553A - Air flow rate detecting element, and air flow sensor - Google Patents

Air flow rate detecting element, and air flow sensor Download PDF

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JP2006010553A
JP2006010553A JP2004189542A JP2004189542A JP2006010553A JP 2006010553 A JP2006010553 A JP 2006010553A JP 2004189542 A JP2004189542 A JP 2004189542A JP 2004189542 A JP2004189542 A JP 2004189542A JP 2006010553 A JP2006010553 A JP 2006010553A
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air flow
resistor
flow rate
sensor
voltage
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JP4089657B2 (en
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Teruaki Umibe
輝明 海部
Yasushi Kono
泰 河野
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Denso Corp
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Denso Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a detecting element 2 and a sensor 1 capable of reducing an influence of a measuring error in a low air flow rate. <P>SOLUTION: The detecting element 2 is formed by connecting the first resistor 3 having a positive resistance temperature coefficient and generating heat by electrification, and the second resistor 4 having a negative resistance temperature coefficient, in parallel electrically each other. Both resistance values of the first and second resistors 3, 4 are reduced thereby because the second resistor 4 is heated to be elevated in a temperature by a temperature-elevated air flow due to heat removal for the first resistor 3, in particular, in the low air flow rate. Sensitivity is enhanced thereby because an electrification quantity is increased as the whole detecting element 2 to make a voltage Va high. Resultingly, the influence of the measuring error with respect to a true value is reduced remarkably in the low air flow rate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、空気流量検出素子、およびこれを用いた空気流量センサに関し、特に、エンジンの吸入空気流量を検出するのに好適な空気流量検出素子および空気流量センサに関する。   The present invention relates to an air flow rate detecting element and an air flow rate sensor using the same, and more particularly to an air flow rate detecting element and an air flow rate sensor suitable for detecting an intake air flow rate of an engine.

〔従来の技術〕
従来より、エンジンの吸入空気流量等の空気流量を検出するために、熱式の空気流量センサが用いられている。熱式の空気流量センサ（以下、センサと呼ぶ）は、配線の一方に空気流量検出素子（以下、検出素子と呼ぶ）が組み込まれたホイーストンブリッジ回路を備える。この検出素子は、通常、正の抵抗温度係数を有し、通電により発熱する抵抗体である。 [Conventional technology]
Conventionally, a thermal air flow sensor has been used to detect an air flow rate such as an intake air flow rate of an engine. A thermal air flow sensor (hereinafter referred to as a sensor) includes a Wheatstone bridge circuit in which an air flow detection element (hereinafter referred to as a detection element) is incorporated in one of the wirings. This detection element is usually a resistor that has a positive resistance temperature coefficient and generates heat when energized.

そして、センサは、検出素子への通電量を調節することにより、通電による発熱や空気流による除熱などを均衡させ検出素子の温度を所定値に合わせるとともに、検出素子の低電位側端子における電圧を空気流量に対応する電気信号として出力する。そして、ＥＣＵ等がこの電気信号の出力値を用いて空気流量を算出することにより、空気流量の計測が行われている。   The sensor adjusts the amount of current supplied to the detection element to balance the heat generated by the current supply and the heat removal by the air flow, etc., and adjust the temperature of the detection element to a predetermined value, and the voltage at the low potential side terminal of the detection element. Is output as an electrical signal corresponding to the air flow rate. The ECU or the like calculates the air flow rate by using the output value of the electrical signal, thereby measuring the air flow rate.

〔従来技術の不具合〕
しかし、このセンサによれば、空気流量が低下すると検出素子の発熱量とともに検出素子への通電量が減少するため、電気信号としての電圧も低下してしまう。このため、低空気流量では電気信号に対するノイズ等の影響が大きくなり、真値に対する計測誤差の影響が大きくなってしまう。 [Problems with conventional technology]
However, according to this sensor, when the air flow rate is reduced, the amount of electricity supplied to the detection element is reduced together with the amount of heat generated by the detection element, so the voltage as an electric signal is also reduced. For this reason, at a low air flow rate, the influence of noise or the like on the electric signal becomes large, and the influence of measurement error on the true value becomes large.

なお、従来の検出素子を改善する技術としては、２つの抵抗体を電気的に並列接続しこれらの抵抗体を空気の流れに沿って上流側から下流側へ配置することにより応答性を向上させたもの（例えば、特許文献１参照）、ドープ処理されたケイ素半導体薄膜で抵抗体を構成することにより抵抗温度係数を向上させたもの（例えば、特許文献２参照）、抵抗率の高い材料を用い抵抗値が約１ｋΩとなるように抵抗体を形成することにより、抵抗体の熱容量を向上させ、より高い範囲の空気流量に対応できるようにしたもの（特許文献３参照）などがある。
しかし、低空気流量での計測誤差の影響については、充分な改善がなされていない。
特開平９−１２６８５０号公報 特開２００１−１９４２０２号公報 特許第２８８０６５１号公報 As a technique for improving the conventional detection element, two resistors are electrically connected in parallel, and these resistors are arranged from the upstream side to the downstream side along the air flow to improve the responsiveness. (For example, see Patent Document 1), a material whose resistance temperature coefficient is improved by forming a resistor with a doped silicon semiconductor thin film (for example, see Patent Document 2), and a material having a high resistivity. There is one that improves the heat capacity of the resistor by forming the resistor so that the resistance value is about 1 kΩ, and can cope with a higher air flow rate (see Patent Document 3).
However, the effect of measurement errors at low air flow rates has not been improved sufficiently.
JP 9-126850 A JP 2001-194202 A Japanese Patent No. 2880651

本発明は、上記の問題点を解決するためになされたものであり、低空気流量での計測誤差の影響を低減することができる空気流量検出素子および空気流量センサを提供することにある。   The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an air flow rate detecting element and an air flow rate sensor that can reduce the influence of measurement errors at a low air flow rate.

〔請求項１の手段〕
請求項１に記載の検出素子は、正の抵抗温度係数を有し、通電により発熱する第１抵抗体と、負の抵抗温度係数を有する第２抵抗体とを、電気的に並列に接続することにより形成される。
これにより、第１抵抗体を空気流に対し上流側に配置し、第２抵抗体を第１抵抗体の下流側に配置すれば、第１抵抗体の除熱を行い昇温した空気流により、第２抵抗体が加熱され昇温する。このため、第１、第２抵抗体の抵抗値が両方とも低下するので、検出素子全体の通電量が増加し検出素子の低電位側端子における電圧が上昇する。この結果、電気信号に対するノイズ等の影響を小さくすることができるので、計測誤差を低減することができる。 [Means of Claim 1]
The detection element according to claim 1 has a positive resistance temperature coefficient, and electrically connects a first resistor that generates heat by energization and a second resistor having a negative resistance temperature coefficient in parallel. Is formed.
As a result, if the first resistor is arranged upstream of the air flow and the second resistor is arranged downstream of the first resistor, the heat of the first resistor is removed to increase the temperature of the air flow. The second resistor is heated to raise the temperature. For this reason, since the resistance values of the first and second resistors both decrease, the energization amount of the entire detection element increases and the voltage at the low potential side terminal of the detection element increases. As a result, it is possible to reduce the influence of noise or the like on the electric signal, so that measurement errors can be reduced.

〔請求項２の手段〕
請求項２に記載の空気流量センサは、請求項１に記載の検出素子を用いて構成される。 [Means of claim 2]
An air flow rate sensor according to a second aspect is configured using the detection element according to the first aspect.

〔請求項３の手段〕
請求項３に記載の空気流量センサでは、第２抵抗体が、空気の流れに対し第１抵抗体の下流側に配置される。 [Means of claim 3]
In the air flow rate sensor according to claim 3, the second resistor is disposed downstream of the first resistor with respect to the air flow.

最良の形態１の空気流量検出素子は、正の抵抗温度係数を有し、通電により発熱する第１抵抗体と、負の抵抗温度係数を有する第２抵抗体とを、電気的に並列に接続することにより形成されている。また、この空気流量検出素子を用いた空気流量センサでは、第２抵抗体が、空気の流れに対し第１抵抗体の下流側に配置されている。   The air flow rate detecting element of the best mode 1 has a positive resistance temperature coefficient, and electrically connects a first resistor that generates heat by energization and a second resistor having a negative resistance temperature coefficient in parallel. It is formed by doing. In the air flow rate sensor using the air flow rate detection element, the second resistor is disposed on the downstream side of the first resistor with respect to the air flow.

〔実施例１の構成〕
実施例１の空気流量センサ（以下、センサと呼ぶ）１の構成を図１および図２に基づいて説明する。センサ１は、例えば、エンジン（図示せず）の吸入空気量を計測するために用いられる。 [Configuration of Example 1]
A configuration of an air flow rate sensor (hereinafter referred to as a sensor) 1 according to the first embodiment will be described with reference to FIGS. 1 and 2. The sensor 1 is used, for example, for measuring an intake air amount of an engine (not shown).

センサ１の空気流量検出素子（以下、検出素子と呼ぶ）２は、図１に示すように、正の抵抗温度係数を有し、通電により発熱する第１抵抗体３と、負の抵抗温度係数を有する第２抵抗体４とを、電気的に並列に接続することにより形成されている。そして、センサ１は、第２抵抗体４が空気の流れに対し第１抵抗体３の下流側に配置されるように、所定の位置に取り付けられる。   As shown in FIG. 1, an air flow rate detection element (hereinafter referred to as a detection element) 2 of the sensor 1 has a positive resistance temperature coefficient, a first resistor 3 that generates heat when energized, and a negative resistance temperature coefficient. The second resistor 4 having the above is formed by electrically connecting in parallel. And the sensor 1 is attached to a predetermined position so that the 2nd resistor 4 may be arrange | positioned in the downstream of the 1st resistor 3 with respect to the flow of air.

第１抵抗体３は、正の抵抗温度係数を有する材料からなり、例えば、白金、金、銅、アルミニウム、クロム、ニッケル、タングステン、パーマロイ等の金属からなる。
第２抵抗体４は、負の抵抗温度係数を有する材料からなり、例えば、シリコン、ガリウムヒ素等の半導体材料や、マンガン、コバルト、ニッケル等の金属酸化物からなる。 The first resistor 3 is made of a material having a positive temperature coefficient of resistance, and is made of a metal such as platinum, gold, copper, aluminum, chromium, nickel, tungsten, and permalloy.
The second resistor 4 is made of a material having a negative resistance temperature coefficient, and is made of, for example, a semiconductor material such as silicon or gallium arsenide, or a metal oxide such as manganese, cobalt, or nickel.

センサ１は、図２に示すように、検出素子２、検出素子２とともに空気の流路に配置され抵抗値が変化する温度補償抵抗体５、および抵抗値が不変である固定抵抗体６、７、８が組み込まれたホイーストンブリッジ回路（以下、ブリッジ回路と呼ぶ）９を有する。   As shown in FIG. 2, the sensor 1 includes a detection element 2, a temperature compensation resistor 5 that is disposed in the air flow path together with the detection element 2, and a fixed resistance body 6, 7 that has a constant resistance value. , 8 incorporated therein, a Wheatstone bridge circuit (hereinafter referred to as a bridge circuit) 9 is included.

ブリッジ回路９では、配線１２に検出素子２が組み込まれ、配線１３に温度補償抵抗体５および固定抵抗体６が直列に組み込まれている。また、配線１２と直列の配線１４に固定抵抗体７が組み込まれ、配線１３と直列の配線１５に固定抵抗体８が組み込まれている。   In the bridge circuit 9, the detection element 2 is incorporated in the wiring 12, and the temperature compensation resistor 5 and the fixed resistor 6 are incorporated in series in the wiring 13. The fixed resistor 7 is incorporated in the wiring 14 in series with the wiring 12, and the fixed resistor 8 is incorporated in the wiring 15 in series with the wiring 13.

配線１２と配線１４との接点ａは、オペアンプ１８の非反転入力端子に接続され、配線１３と配線１５との接点ｂは、オペアンプ１８の反転入力端子に接続されている。また、接点ａと非反転入力端子とを接続する配線１９から、接点ａの電圧Ｖａを電気信号として出力するための配線２０が分岐し、空気流量の算出を行うＥＣＵ（図示せず）の接続端子ｃに連結している。なお、配線２０には周知の増幅器２２が組み込まれ電気信号が増幅される。   A contact a between the wiring 12 and the wiring 14 is connected to a non-inverting input terminal of the operational amplifier 18, and a contact b between the wiring 13 and the wiring 15 is connected to an inverting input terminal of the operational amplifier 18. Further, a wiring 20 for outputting the voltage Va of the contact a as an electric signal branches from the wiring 19 connecting the contact a and the non-inverting input terminal, and an ECU (not shown) for calculating the air flow rate is connected. It is connected to the terminal c. Note that a well-known amplifier 22 is incorporated in the wiring 20 to amplify an electric signal.

オペアンプ１８の出力端子はトランジスタ２４のベース端子に接続されている。さらに、トランジスタ２４のコレクタ端子は、ブリッジ回路９へ電力を供給する電源（図示せず）の接続端子ｄに接続され、エミッタ端子は配線１２と配線１３との接点ｅに接続されている。なお、配線１４と配線１５との接点ｆは接地されている。   The output terminal of the operational amplifier 18 is connected to the base terminal of the transistor 24. Further, the collector terminal of the transistor 24 is connected to a connection terminal d of a power source (not shown) that supplies power to the bridge circuit 9, and the emitter terminal is connected to a contact point e between the wiring 12 and the wiring 13. The contact f between the wiring 14 and the wiring 15 is grounded.

〔実施例１の特徴〕
実施例１のセンサ１の特徴を説明する。なお、センサ１は、オペアンプ１８およびトランジスタ２４の作動により、第１抵抗体３の発熱量を空気流による除熱量等と均衡させ第１抵抗体３を所定温度に維持するように作用する熱式定温度型である。また、センサ１は、空気流量に相当する電気信号として、電圧Ｖａを検出し増幅した後、ＥＣＵへ出力する。そして、ＥＣＵは、この電気信号の出力値を用いて空気流量を算出する。 [Features of Example 1]
The characteristics of the sensor 1 according to the first embodiment will be described. The sensor 1 is operated by the operational amplifier 18 and the transistor 24 so that the amount of heat generated by the first resistor 3 is balanced with the amount of heat removed by the air flow and the like, so that the first resistor 3 is maintained at a predetermined temperature. Constant temperature type. Further, the sensor 1 detects and amplifies the voltage Va as an electric signal corresponding to the air flow rate, and then outputs it to the ECU. Then, the ECU calculates the air flow rate using the output value of this electrical signal.

第１抵抗体３は、通電により発熱するとともに空気流により除熱される。そして、空気流量が増加し空気流による第１抵抗体３からの除熱量が増加すると、センサ１は、第１抵抗体３の温度を所定値に維持するため第１抵抗体３の発熱量（すなわち、通電量）を大きくする方向に作用する。このため、図３の相関線Ａに示すように、第１抵抗体３の通電量は空気流量の増大とともに増加する。   The first resistor 3 generates heat when energized and is removed by an air flow. When the air flow rate increases and the amount of heat removed from the first resistor 3 due to the air flow increases, the sensor 1 maintains the temperature of the first resistor 3 at a predetermined value, and the amount of heat generated by the first resistor 3 ( That is, it acts in the direction of increasing the energization amount). For this reason, as shown by the correlation line A in FIG. 3, the energization amount of the first resistor 3 increases as the air flow rate increases.

一方、第２抵抗体４は、第１抵抗体３からの除熱により昇温した空気流によって加熱される。そして、空気流量が増大し第１抵抗体３からの除熱量が増加すると、昇温した空気流による第２抵抗体４の加熱量も増加する。ここで、第２抵抗体４は負の抵抗温度係数を有するので、加熱量が増加することにより昇温すると、抵抗値が低下し通電量が増加する。このため、図３の相関線Ｂに示すように、第２抵抗体４の通電量も空気流量の増大とともに増加する。   On the other hand, the second resistor 4 is heated by the air flow that has been heated by heat removal from the first resistor 3. When the air flow rate is increased and the amount of heat removed from the first resistor 3 is increased, the amount of heating of the second resistor 4 by the heated air flow is also increased. Here, since the second resistor 4 has a negative resistance temperature coefficient, when the temperature is increased by increasing the heating amount, the resistance value decreases and the energization amount increases. For this reason, as shown by the correlation line B in FIG. 3, the energization amount of the second resistor 4 also increases as the air flow rate increases.

以上により、図３の相関線Ｃに示すように、第１抵抗体３の通電量と第２抵抗体４の通電量とを合計した検出素子２の通電量は、空気流量の増大とともに増加する。この結果、電圧Ｖａは空気流量の増大とともに大きくなるので、ＥＣＵへの出力値も、図４の相関線Ｄに示すように、空気流量の増大とともに大きくなる。さらに、相関線Ｄの勾配、すなわち空気流量に対する出力値の増加率（以下、感度と呼ぶ）は、第１抵抗体３のみで検出素子２を構成したときの相関線Ｅより大きくなる。   As described above, as indicated by the correlation line C in FIG. 3, the energization amount of the detection element 2 that is the sum of the energization amount of the first resistor 3 and the energization amount of the second resistor 4 increases as the air flow rate increases. . As a result, the voltage Va increases as the air flow rate increases, so that the output value to the ECU also increases as the air flow rate increases as shown by the correlation line D in FIG. Further, the gradient of the correlation line D, that is, the rate of increase of the output value with respect to the air flow rate (hereinafter referred to as sensitivity) is larger than the correlation line E when the detection element 2 is configured by only the first resistor 3.

〔実施例１の作用〕
実施例１のセンサ１の作用を説明する。
例えば、電圧Ｖａが接点ｂの電圧Ｖｂよりも大きくなると、オペアンプ１８において非反転入力端子の入力電圧の方が反転入力端子の入力電圧よりも大きくなるので出力電圧は高電圧ＶＨになる。これにより、ベース端子にかかる電圧が大きくなるので、電源からブリッジ回路９に供給される電力が増加する。このため、検出素子２における通電量が増加し、第１抵抗体３は発熱量が増加して昇温するので、第１抵抗体３の抵抗値が上昇する。これにより、電圧Ｖａが下がり、やがて電圧Ｖａが電圧Ｖｂよりも小さくなる。 [Operation of Example 1]
The operation of the sensor 1 according to the first embodiment will be described.
For example, when the voltage Va becomes higher than the voltage Vb of the contact b, the output voltage becomes the high voltage VH because the input voltage of the non-inverting input terminal is higher than the input voltage of the inverting input terminal in the operational amplifier 18. As a result, the voltage applied to the base terminal increases, so that the power supplied from the power source to the bridge circuit 9 increases. For this reason, the energization amount in the detection element 2 is increased, and the first resistor 3 is heated by increasing the heat generation amount, so that the resistance value of the first resistor 3 is increased. As a result, the voltage Va decreases and eventually the voltage Va becomes smaller than the voltage Vb.

電圧Ｖａが電圧Ｖｂよりも小さくなると、オペアンプ１８において非反転入力端子の入力電圧の方が反転入力端子の入力電圧よりも小さくなるので出力電圧は低電圧ＶＬになる。これにより、ベース端子にかかる電圧が小さくなるので、電源からブリッジ回路９に供給される電力が減少する。このため、検出素子２における通電量が減少し、第１抵抗体３は発熱量が減少して降温するので、第１抵抗体３の抵抗値が低下する。これにより、電圧Ｖａが上がり、やがて電圧Ｖａが電圧Ｖｂよりも大きくなる。   When the voltage Va becomes smaller than the voltage Vb, in the operational amplifier 18, the input voltage at the non-inverting input terminal becomes smaller than the input voltage at the inverting input terminal, so that the output voltage becomes the low voltage VL. As a result, the voltage applied to the base terminal is reduced, and the power supplied from the power source to the bridge circuit 9 is reduced. For this reason, the energization amount in the detection element 2 decreases, and the first resistor 3 decreases in temperature because the heat generation amount decreases, so that the resistance value of the first resistor 3 decreases. As a result, the voltage Va increases and eventually the voltage Va becomes larger than the voltage Vb.

このように、電圧Ｖａが電圧Ｖｂよりも大きくなるので、再度、オペアンプ１８からの出力電圧が高電圧ＶＨになり、同様の作用が繰り返される。これにより、センサ１は、空気流量の変動に対して応答し、電圧Ｖａを空気流量に応じた値に変化させることができる。   Thus, since the voltage Va becomes larger than the voltage Vb, the output voltage from the operational amplifier 18 becomes the high voltage VH again, and the same operation is repeated. Thereby, the sensor 1 can respond to the fluctuation | variation of an air flow rate, and can change the voltage Va to the value according to the air flow rate.

〔実施例１の効果〕
実施例１のセンサ１では、検出素子２が、正の抵抗温度係数を有し、通電により発熱する第１抵抗体３と、負の抵抗温度係数を有する第２抵抗体４とを、電気的に並列に接続することにより形成されている。そして、センサ１は、第２抵抗体４が空気の流れに対し第１抵抗体３の下流側に配置されるように、所定の位置に取り付けられる。
これにより、第１抵抗体３の除熱を行い昇温した空気流により、第２抵抗体４が加熱され昇温するため、第１、第２抵抗体３、４の抵抗値が両方とも低下する。また、第２抵抗体４の抵抗値の低下は、低空気流量で顕著である。このため、特に、低空気流量で検出素子２全体の通電量が増加し電圧Ｖａが大きくなる。この結果、図４に示すように、第１抵抗体３のみで検出素子２を構成するとき（相関線Ｅ）よりも、第１、第２抵抗体３、４で検出素子２を構成するとき（相関線Ｄ）の方が、低空気流量での感度が向上する。 [Effect of Example 1]
In the sensor 1 according to the first embodiment, the detection element 2 includes a first resistor 3 having a positive resistance temperature coefficient and generating heat when energized, and a second resistor 4 having a negative resistance temperature coefficient. Are connected in parallel. And the sensor 1 is attached to a predetermined position so that the 2nd resistor 4 may be arrange | positioned in the downstream of the 1st resistor 3 with respect to the flow of air.
As a result, the second resistor 4 is heated and heated by the air flow that has been removed by removing heat from the first resistor 3, and the resistance values of the first and second resistors 3 and 4 both decrease. To do. Further, the decrease in the resistance value of the second resistor 4 is significant at a low air flow rate. For this reason, in particular, the energization amount of the entire detection element 2 increases and the voltage Va increases at a low air flow rate. As a result, as shown in FIG. 4, when the detection element 2 is configured with the first and second resistors 3 and 4, rather than when the detection element 2 is configured with only the first resistor 3 (correlation line E). (Correlation line D) improves sensitivity at a low air flow rate.

この結果、空気流量の真値に対する計測誤差の影響を、低空気流量で顕著に低減することができる。すなわち、電気信号の出力は、感度や出力値の大小に関わらず、一様にノイズ等の影響を受ける。このため、出力値は、例えば一様に偏差εだけ増加し、計測誤差が発生する。しかし、感度が向上すると、例えば、同じ真値Ｘ１に対する計測誤差は、値ΔＸＥから値ΔＸＤへ減少する。このように、感度を向上させれば、真値に対するノイズ等による計測誤差の影響を低減することができる。   As a result, the influence of the measurement error on the true value of the air flow rate can be significantly reduced at a low air flow rate. That is, the output of the electric signal is uniformly affected by noise and the like regardless of the sensitivity and the output value. For this reason, the output value increases, for example, by the deviation ε uniformly, and a measurement error occurs. However, when the sensitivity is improved, for example, the measurement error for the same true value X1 decreases from the value ΔXE to the value ΔXD. Thus, if the sensitivity is improved, it is possible to reduce the influence of the measurement error due to noise or the like on the true value.

空気流量検出素子の構成図である（実施例１）。(Example 1) which is a block diagram of an air flow rate detection element. 空気流量センサの回路図である（実施例１）。(Example 1) which is a circuit diagram of an air flow sensor. 空気流量検出素子の通電量と空気流量との相関図である（実施例１）。(Example 1) which is a correlation diagram of the energization amount of an air flow rate detection element, and an air flow rate. 空気流量センサからの出力値と空気流量との相関図である（実施例１）。(Example 1) which is a correlation diagram of the output value from an air flow rate sensor, and an air flow rate.

符号の説明Explanation of symbols

１ 空気流量センサ
２ 空気流量検出素子
３ 第１抵抗体
４ 第２抵抗体 DESCRIPTION OF SYMBOLS 1 Air flow sensor 2 Air flow detection element 3 1st resistor 4 2nd resistor

Claims (3)

正の抵抗温度係数を有し、通電により発熱する第１抵抗体と、
負の抵抗温度係数を有する第２抵抗体とを、
電気的に並列に接続することにより形成された空気流量検出素子。 A first resistor having a positive resistance temperature coefficient and generating heat upon energization;
A second resistor having a negative resistance temperature coefficient,
An air flow rate detecting element formed by electrically connecting in parallel. 請求項１に記載の空気流量検出素子を用いた空気流量センサ。   An air flow rate sensor using the air flow rate detection element according to claim 1. 請求項２に記載の空気流量センサにおいて、
前記第２抵抗体は、空気の流れに対し前記第１抵抗体の下流側に配置されることを特徴とする空気流量センサ。 The air flow sensor according to claim 2,
The air flow sensor, wherein the second resistor is arranged downstream of the first resistor with respect to an air flow.
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