JPH0233966B2 - - Google Patents
Info
- Publication number
- JPH0233966B2 JPH0233966B2 JP56186324A JP18632481A JPH0233966B2 JP H0233966 B2 JPH0233966 B2 JP H0233966B2 JP 56186324 A JP56186324 A JP 56186324A JP 18632481 A JP18632481 A JP 18632481A JP H0233966 B2 JPH0233966 B2 JP H0233966B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- voltage dividing
- series
- burn
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 239000002184 metal Substances 0.000 claims description 13
- 239000000498 cooling water Substances 0.000 claims description 9
- 238000002485 combustion reaction Methods 0.000 claims description 6
- 238000001514 detection method Methods 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 230000007423 decrease Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000000446 fuel Substances 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- G01F1/696—Circuits therefor, e.g. constant-current flow meters
- G01F1/698—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters
- G01F1/6983—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters adapted for burning-off deposits
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Description
【発明の詳細な説明】 本発明は内燃機関の熱線流量計に関する。[Detailed description of the invention] The present invention relates to a hot wire flowmeter for an internal combustion engine.
燃料噴射弁によつて機関へ燃料を供給する方式
の内燃機関においては、機関に吸入される吸入空
気量に応じて噴射弁の開閉が制御されるようにな
つており、この吸入空気量を測定するために吸入
空気流量計が設けられている。かかる吸入空気流
量計として吸入空気路に所定金属線を張設してこ
れに所定電流を流し、空気流速の変動に応じた金
属線の抵抗変化により吸入空気流量を測定する熱
線流量計がある。 In internal combustion engines that supply fuel to the engine through fuel injection valves, the opening and closing of the injection valves is controlled according to the amount of intake air taken into the engine, and this amount of intake air is measured. An intake air flow meter is provided for this purpose. As such an intake air flowmeter, there is a hot wire flowmeter that measures the intake air flow rate by extending a predetermined metal wire in the intake air path, passing a predetermined current through the wire, and measuring the resistance change of the metal wire in response to fluctuations in air flow velocity.
第１図は、かかる熱線流量計の従来回路例を示
している。第１図において、熱線RHは、好まし
くは白金からなる金属線であり、抵抗R1，R2，
R3と共にブリツジ回路１を形成している。抵抗
R1を含む辺には温度補償用の抵抗RKが抵抗R1に
直列に接続されており、抵抗RKは熱線RH及び抵
抗R3と共に吸入空気路２内に設けられている。
ブリツジ回路１の熱線RHと抵抗RKとの接続点ａ
は電源端であり、抵抗R2とR3との接続点ｂは接
地されている。また、熱線RHと抵抗R3との接続
点ｃ及び抵抗R1とR2との接続点ｄは演算増幅器
３及び抵抗R4，R5等からなる差動増幅回路に接
続されている。差動増幅回路は接続点ｃとｄとの
電位差に比例した電圧を出力端に発生し、この電
圧は抵抗R6を介してトランジスタQ1のベースに
印加される。トランジスタQ1のエミツタには並
列に接続されたイグニシヨンスイツチ４と遅延ス
イツチ回路５とを介して電源電圧VBが供給され、
コレクタは接続点ａに接続されている。また抵抗
R2には並列に抵抗R7とトランジスタQ2との直列
回路が接続され、トランジスタQ2のベースには
抵抗R8を介してパルス発生回路６が接続されて
いる。遅延スイツチ回路５及びパルス発生回路６
にはイグニシヨンオフ検出回路７が接続されてお
り、イグニシヨンオフ検出回路７はイグニシヨン
スイツチ４のオンからオフへの切換え動作を検出
して検出信号を発生するようになつている。 FIG. 1 shows an example of a conventional circuit for such a hot wire flowmeter. In FIG. 1, the hot wire R H is preferably a metal wire made of platinum, and the resistors R 1 , R 2 ,
Together with R3 , it forms a bridge circuit 1. resistance
A temperature compensation resistor R K is connected in series with the resistor R 1 on the side including R 1 , and the resistor R K is provided in the intake air path 2 together with the hot wire R H and the resistor R 3 .
Connection point a between hot wire R H and resistor R K of bridge circuit 1
is the power supply terminal, and the connection point b between resistors R 2 and R 3 is grounded. Further, a connection point c between the hot wire R H and the resistor R 3 and a connection point d between the resistors R 1 and R 2 are connected to a differential amplifier circuit including an operational amplifier 3, resistors R 4 and R 5 , and the like. The differential amplifier circuit generates at its output a voltage proportional to the potential difference between connection points c and d, and this voltage is applied to the base of transistor Q 1 via resistor R 6 . A power supply voltage V B is supplied to the emitter of the transistor Q 1 via an ignition switch 4 and a delay switch circuit 5 which are connected in parallel.
The collector is connected to connection point a. Also resistance
A series circuit of a resistor R7 and a transistor Q2 is connected in parallel to R2, and a pulse generating circuit 6 is connected to the base of the transistor Q2 via a resistor R8 . Delay switch circuit 5 and pulse generation circuit 6
An ignition-off detection circuit 7 is connected to the ignition-off detection circuit 7, and the ignition-off detection circuit 7 detects the switching operation of the ignition switch 4 from on to off and generates a detection signal.
上記構成の熱線流量計において、熱線RHは機
関作動中に通電加熱され、吸入空気流速に応じた
度合で冷却されてその抵抗値が変化する。この熱
線RHの抵抗値は熱線RHを流れる電流に応じて変
化する接続点ｃの電圧により検出されている。こ
の電圧は吸入空気流量に対応したものであり、信
号処理回路（図示せず）において機関への燃料供
給制御のための演算処理に用いられる。また熱線
RHの抵抗値の変化による接続点ｃ，ｄの電位差
はトランジスタQ1のベース電圧を変化せしめ、
トランジスタQ1からブリツジ回路１へ供給され
る電流は熱線RHの抵抗値を一定に保つように増
減する。 In the hot wire flowmeter having the above configuration, the hot wire R H is heated by electricity during engine operation, and is cooled to a degree corresponding to the intake air flow rate, so that its resistance value changes. The resistance value of the hot wire R H is detected by the voltage at the connection point c, which changes depending on the current flowing through the hot wire R H. This voltage corresponds to the intake air flow rate, and is used in a signal processing circuit (not shown) for arithmetic processing to control fuel supply to the engine. Also heat rays
The potential difference between the connection points c and d due to the change in the resistance value of R H changes the base voltage of the transistor Q1 ,
The current supplied from the transistor Q 1 to the bridge circuit 1 increases or decreases so as to keep the resistance value of the hot wire R H constant.
ところで、吸入空気路に配置された熱線RHに
は吸気中に混在する塵芥等が付着し易い、特に、
機関の圧縮及び爆発行程のときピストンとシリン
ダのすき間からクランク室に吹き抜けるブローバ
イガスを再燃焼させるべく熱線RHの上流の吸入
空気路に流し込む場合には、ブローバイガス中に
未燃焼物を含むため短期間の内に多量の付着物を
生じる。しかし、その付着物を放置すると熱線流
量計の感度ないし測定精度の低下は避けられない
ことになる。このため、次のようにして付着物を
取り除くことが行なわれている。先ず、イグニシ
ヨンスイツチ４がオンからオフになるとイグニシ
ヨンオフ検出回路７が検出信号を発生し、検出信
号は遅延スイツチ回路５及びパルス発生回路６に
供給される。遅延スイツチ回路５は検出信号に応
じて所定期間オン状態になり、その期間電圧VB
をトランジスタQ1のエミツタ及びパルス発生回
路６に供給する（ただし、パルス発生回路６への
電源ラインは図示せず）。一方、パルス発生回路
６は、例えば単安定マルチ発振器からなり、検出
信号に応じて所定幅の焼切指令パルスを発生す
る。この焼切指令パルスはトランジスタQ2のベ
ースに供給されトランジスタQ2をオン状態にせ
しめる。トランジスタQ2がオン状態になると、
抵抗R2とR7とが電気的に並列接続されたことに
なる故に接続点ｄの電圧は大幅に減少する。次い
で、接続点ｃ，ｄ間の電位差に応じて演算増幅器
３の出力電圧が大きく低下してトランジスタQ1
のコレクタ電流は最大レベルに達し、よつて、熱
線RHを流れる電流が増えて熱線RHの温度が上昇
し、付着物が焼除されるのである。 By the way, the hot wire R H placed in the intake air passage is prone to attract dust, etc. mixed in the intake air.
When the blow-by gas that blows into the crank chamber through the gap between the piston and cylinder during the compression and explosion strokes of the engine is poured into the intake air passage upstream of the hot wire R H for re-burning, the blow-by gas contains unburned substances. Generates a large amount of deposits within a short period of time. However, if the deposits are left unattended, the sensitivity or measurement accuracy of the hot wire flowmeter will inevitably decrease. For this reason, the deposits are removed in the following manner. First, when the ignition switch 4 is turned from on to off, the ignition-off detection circuit 7 generates a detection signal, and the detection signal is supplied to the delay switch circuit 5 and the pulse generation circuit 6. The delay switch circuit 5 is in an on state for a predetermined period according to the detection signal, and during that period the voltage V B
is supplied to the emitter of the transistor Q1 and the pulse generation circuit 6 (however, the power supply line to the pulse generation circuit 6 is not shown). On the other hand, the pulse generation circuit 6 is composed of, for example, a monostable multi-oscillator, and generates a burnout command pulse of a predetermined width in accordance with the detection signal. This burnout command pulse is supplied to the base of transistor Q 2 and turns transistor Q 2 on. When transistor Q2 turns on,
Since the resistors R 2 and R 7 are electrically connected in parallel, the voltage at the connection point d is significantly reduced. Next, the output voltage of the operational amplifier 3 decreases significantly depending on the potential difference between the connection points c and d, and the transistor Q 1
The collector current reaches its maximum level, so the current flowing through the hot wire R H increases, the temperature of the hot wire R H increases, and the deposits are burned away.
しかしながら、上記のように従来の熱線流量計
においては、イグニシヨンスイツチ４がオンから
オフになる毎に熱線RHに付着物焼除のための高
電流が流れる。このため、例えば、低温時の機関
始動ミス時や機関温度が所定レベルまで上昇しな
い極めて短時間の運転終了時にも熱線RHには高
電流が流れるため熱線の劣化が早いという問題点
があつた。 However, as described above, in the conventional hot wire flowmeter, a high current for burning out deposits flows through the hot wire R H every time the ignition switch 4 is turned from on to off. For this reason, for example, there was a problem in that the hot wire deteriorated quickly because a high current flowed through the hot wire R H even when the engine failed to start at low temperatures or when the engine ended for a very short time when the engine temperature did not rise to a predetermined level. .
そこで、本発明の目的は、急速な熱線の劣化を
防止し得る熱線流量計を提供することにある。 Therefore, an object of the present invention is to provide a hot wire flowmeter that can prevent rapid deterioration of the hot wire.
本願第１の発明による熱線流量計は、内燃機関
の吸入空気路に設けられた金属線と該金属線に直
列に接続された抵抗とによる第１分圧回路と、直
列接続された複数の抵抗による第２分圧回路と、
第１及び第２分圧回路の分圧電圧の電位差を検出
する電位差検出手段と、第１及び第２分圧回路の
一端に直列に接続され電位差検出手段の出力信号
に応じて作動する能動素子と、第１及び第２分圧
回路と能動素子との直列回路の両端間に電圧を供
給する電源と、イグニツシヨンスイツチがオンか
らオフになると金属線の付着物を焼切除去すべく
所定期間第２分圧回路の分圧電圧を変化させる焼
切作動手段とを含み、機関冷却水温に応じて焼切
作動手段による焼切動作を禁止する焼切禁止手段
を有することを特徴としている。また、本願第２
の発明による熱線流量計は、内燃機関の吸入空気
路に設けられた金属線と該金属線に直列に接続さ
れた抵抗とによる第１分圧回路と、直列接続され
た複数の抵抗による第２分圧回路と、第１及び第
２分圧回路の分圧電圧の電位差を検出する電位差
検出手段と、第１及び第２分圧回路の一端に直列
に接続され電位差検出手段の出力信号に応じて作
動する能動素子と、第１及び第２分圧回路と能動
素子との直列回路の両端間に電圧を供給する電源
と、イグニツシヨンスイツチがオンからオフにな
ると金属線の付着物を焼切除去すべく所定期間第
２分圧回路の分圧電圧を変化させる焼切作動手段
とを含み、イグニツシヨンスイツチのオン状態に
おいて機関回転数が所定回転数を越えない限り焼
切作動手段による焼切動作を禁止する焼切禁止手
段を有することを特徴としている。 The hot wire flowmeter according to the first invention of the present application includes a first voltage dividing circuit including a metal wire provided in an intake air path of an internal combustion engine and a resistor connected in series to the metal wire, and a plurality of resistors connected in series. a second voltage divider circuit,
Potential difference detection means for detecting the potential difference between the divided voltages of the first and second voltage divider circuits; and an active element connected in series to one end of the first and second voltage divider circuits and activated according to the output signal of the potential difference detection means. , a power source that supplies voltage across the series circuit of the first and second voltage divider circuits and the active element, and a predetermined power supply that burns off and removes deposits on the metal wires when the ignition switch is turned from on to off. The present invention is characterized in that it includes a burnout actuation means for changing the divided voltage of the second voltage dividing circuit for a period, and a burnout prohibition means for prohibiting the burnout operation by the burnout actuation means in accordance with the engine cooling water temperature. In addition, the second application
The hot wire flowmeter according to the invention includes a first voltage dividing circuit including a metal wire provided in an intake air path of an internal combustion engine and a resistor connected in series to the metal wire, and a second voltage dividing circuit including a plurality of resistors connected in series. a voltage dividing circuit; a potential difference detecting means for detecting the potential difference between the divided voltages of the first and second voltage dividing circuits; A power supply that supplies voltage across a series circuit of the first and second voltage divider circuits and the active element, and burns out deposits on metal wires when the ignition switch is turned from on to off. The burnout actuation means changes the divided voltage of the second voltage dividing circuit for a predetermined period of time in order to remove the engine. It is characterized by having a burn-off prohibition means for prohibiting burn-off operation.
以下、本発明の実施例を第２図を参照して説明
する。 Hereinafter, embodiments of the present invention will be described with reference to FIG.
第２図において、第１図と同等部分は同一符号
で示されており、トランジスタQ1のエミツタと
アースとの間には抵抗R9及びサーミスタ８によ
る分圧回路からなる機関冷却水温測定用の水温セ
ンサ９が接続されている。水温センサ９の出力端
には比較回路１０が接続されている。比較回路１
０には別に所定電圧Vrが供給されると共に比較
回路１０の出力端にはトランジスタQ3のベース
が接続されている。トランジスタQ3のコレク
タ・エミツタ間はトランジスタQ2のエミツタと
アースとの間に直列に接続されている。本発明に
よる熱線流量計のその他の構成は第１図に示した
従来例と同様であるのでここでは説明を省略す
る。 In Fig. 2, parts equivalent to those in Fig. 1 are indicated by the same symbols, and between the emitter of transistor Q1 and ground is a voltage dividing circuit consisting of resistor R9 and thermistor 8 for measuring engine cooling water temperature. A water temperature sensor 9 is connected. A comparison circuit 10 is connected to the output end of the water temperature sensor 9. Comparison circuit 1
0 is separately supplied with a predetermined voltage V r , and the output terminal of the comparator circuit 10 is connected to the base of the transistor Q 3 . The collector and emitter of transistor Q3 are connected in series between the emitter of transistor Q2 and ground. The rest of the configuration of the hot wire flowmeter according to the present invention is the same as that of the conventional example shown in FIG. 1, so a description thereof will be omitted here.
かかる構成の本発明による熱線流量計において
は、イグニシヨンスイツチ４がオンからオフにな
ると従来と同様に検出信号が遅延スイツチ回路５
及びパルス発生回路６に供給され、遅延スイツチ
回路５は所定期間電圧VBをトランジスタQ1のエ
ミツタ、パルス発生回路６及び比較回路１０に供
給する（ただし、パルス発生回路６及び比較回路
１０への電源ラインは図示せず）。また、パルス
発生回路６は所定幅の焼切指令パルスを発生す
る。しかし、機関冷却水温が所定温度以上でなけ
ればトランジスタQ2はオン状態にならない。水
温センサ９は第３図のように冷却水温の上昇に応
じて出力電圧が減少する特性を有しているので、
例えば冷却水温が所定温度Ｔ℃より大のときには
水温センサ９の出力電圧は所定温度Ｔ℃に対応す
る所定電圧Vrより小であるため比較回路１０の
出力は高レベルになる。この高レベルはトランジ
スタQ3をオン状態にせしめるためトランジスタ
Q2もオン状態になる。よつて、熱線RHに高電流
が流れて付着物が焼除される。ところが、低温時
の機関始動ミスによりイグニシヨンスイツチ４が
オンからオフになると、冷却水温が所定温度Ｔ℃
より小であるため水温センサ９の出力電圧は所定
電圧Vrより大である。よつて比較回路１０の出
力レベルは低レベルであり、トランジスタQ2，
Q3がオフ状態にあるため、ブリツジ回路１の接
続点ｄの電圧が大幅に減少することがない。故に
イグニシヨンスイツチ４がオンからオフになつて
も冷却水温が所定温度Ｔ℃以下であるときには熱
線RHに高電流が流れることがないのである。 In the hot wire flowmeter according to the present invention having such a configuration, when the ignition switch 4 is turned from on to off, the detection signal is sent to the delay switch circuit 5 as in the conventional case.
and the pulse generation circuit 6, and the delay switch circuit 5 supplies the voltage VB for a predetermined period to the emitter of the transistor Q1 , the pulse generation circuit 6, and the comparison circuit 10 (however, the voltage VB to the pulse generation circuit 6 and the comparison circuit 10 is (Power lines not shown). Further, the pulse generating circuit 6 generates a burnout command pulse having a predetermined width. However, unless the engine cooling water temperature is above a predetermined temperature, transistor Q2 will not turn on. The water temperature sensor 9 has a characteristic that the output voltage decreases as the cooling water temperature increases, as shown in FIG.
For example, when the cooling water temperature is higher than the predetermined temperature T° C., the output voltage of the water temperature sensor 9 is smaller than the predetermined voltage V r corresponding to the predetermined temperature T° C., so the output of the comparison circuit 10 becomes a high level. This high level turns on the transistor Q3 to turn it on.
Q 2 also turns on. Therefore, a high current flows through the hot wire R H and the deposits are burned away. However, when the ignition switch 4 is turned from on to off due to an error in starting the engine at low temperatures, the cooling water temperature drops below the predetermined temperature T°C.
Therefore, the output voltage of the water temperature sensor 9 is larger than the predetermined voltage Vr . Therefore, the output level of the comparison circuit 10 is low level, and the transistors Q 2 ,
Since Q3 is in the off state, the voltage at the connection point d of the bridge circuit 1 does not decrease significantly. Therefore, even when the ignition switch 4 is turned from on to off, when the cooling water temperature is below the predetermined temperature T.degree. C., no high current flows through the hot wire R.sub.H.
このように、本発明による熱線流量計によれ
ば、イグニシヨンスイツチがオンからオフになつ
たときに機関冷却水温等の機関の運転状態に応じ
て熱線の付着物焼切除去のための高電流を熱線に
流すことが禁止される。よつて、低温時の機関始
動ミス等の熱線に付着物がほとんど生じないとき
には焼切動作が行なわれないため熱線の急速な性
能の劣化を防止することができるのである。 As described above, according to the hot wire flowmeter according to the present invention, when the ignition switch is turned from on to off, a high current is applied to burn off and remove deposits on the hot wire depending on the operating state of the engine such as the engine cooling water temperature. It is prohibited to expose it to hot wires. Therefore, when there is almost no deposit on the hot wire, such as when the engine starts incorrectly at a low temperature, the burnout operation is not performed, and rapid deterioration of the performance of the hot wire can be prevented.
なお、上記した実施例は本願第１の発明の実施
例であり、本願第２の発明の実施例を次に第４図
を参照して説明する。第４図において、クランク
角センサ（図示せず）の出力パルスが供給される
Ｆ−Ｖ（周波数−電圧）変換器１１は入力パルス
の発生周波数に応じた電圧を発生する。クランク
角センサは機関のクランクシヤフトの回転に応じ
てパルスを発生し、機関回転数が増加するほどパ
ルスの発生周期が短くなる。このため、Ｆ−Ｖ変
換器１１の出力電圧も機関回転数が増加するほど
大きくなり、この出力電圧の最大電圧はレベル検
出器１２によつて遅延スイツチ５がオフになつて
電源供給が停止するまで保持される。比較回路１
３はレベル検出器１２の出力電圧と所定電圧Vr1
とを比較する。レベル検出器１２の出力電圧が所
定電圧Vr1より大のときには比較回路１３の出力
は高レベルになる。従つて、パルス発生回路６が
焼切指令パルスを発生し、比較回路１３の出力が
高レベルであれば、トランジスタQ2，Q3が共に
オン状態になり、よつて熱線RHに高電流が流れ
る。しかし、イグニシヨンスイツチがオン状態に
おける最高機関回転数が所定回転数以下の場合に
は比較回路１３の出力は低レベルであるため焼切
指令パルスが発生してもトランジスタQ2，Q3は
オフ状態となり付着物の焼切除去は行なわれない
のである。 The above-mentioned embodiment is an embodiment of the first invention of the present application, and an embodiment of the second invention of the present application will be described next with reference to FIG. 4. In FIG. 4, an F-V (frequency-voltage) converter 11 to which output pulses from a crank angle sensor (not shown) is supplied generates a voltage according to the generation frequency of the input pulses. The crank angle sensor generates pulses according to the rotation of the engine crankshaft, and the pulse generation period becomes shorter as the engine rotation speed increases. Therefore, the output voltage of the F-V converter 11 increases as the engine speed increases, and the level detector 12 turns off the delay switch 5 at the maximum output voltage, stopping the power supply. will be retained until Comparison circuit 1
3 is the output voltage of the level detector 12 and the predetermined voltage V r1
Compare with. When the output voltage of the level detector 12 is higher than the predetermined voltage Vr1 , the output of the comparison circuit 13 becomes high level. Therefore, when the pulse generation circuit 6 generates a burnout command pulse and the output of the comparison circuit 13 is at a high level, both transistors Q 2 and Q 3 are turned on, and a high current is applied to the hot wire R H. flows. However, if the maximum engine speed when the ignition switch is on is below the predetermined speed, the output of the comparator circuit 13 is at a low level, so even if a burnout command pulse is generated, transistors Q 2 and Q 3 are turned off. As a result, the deposits cannot be removed by burning off.
第１図は熱線流量計の従来例を示す回路図、第
２図は本願第１の発明の熱線流量計の実施例を示
す回路図、第３図は第２図の水温センサの出力特
性図、第４図は本願第２の発明の実施例を示す回
路図である。
主要部分の符号の説明、１……ブリツジ回路、
３……演算増幅器、４……イグニシヨンスイツ
チ、５……遅延スイツチ回路、６……パルス発生
回路、７……イグニシヨンオフ検出回路、９……
水温センサ、１０，１３……比較回路。
Fig. 1 is a circuit diagram showing a conventional example of a hot wire flowmeter, Fig. 2 is a circuit diagram showing an embodiment of the hot wire flowmeter of the first invention of the present application, and Fig. 3 is an output characteristic diagram of the water temperature sensor shown in Fig. 2. , FIG. 4 is a circuit diagram showing an embodiment of the second invention of the present application. Explanation of symbols of main parts, 1...Bridge circuit,
3... operational amplifier, 4... ignition switch, 5... delay switch circuit, 6... pulse generation circuit, 7... ignition off detection circuit, 9...
Water temperature sensor, 10, 13...comparison circuit.
Claims (1)
該金属線に直列に接続された抵抗とによる第１分
圧回路と、直列接続された複数の抵抗による第２
分圧回路と、前記第１及び第２分圧回路の分圧電
圧の電位差を検出する電位差検出手段と、前記第
１及び第２分圧回路の一端に直列に接続され前記
電位差検出手段の出力信号に応じて作動する能動
素子と、前記第１及び第２分圧回路と前記能動素
子との直列回路の両端間に電圧を供給する電源
と、イグニツシヨンスイツチがオンからオフにな
ると前記金属線の付着物を焼切除去すべく所定期
間前記第２分圧回路の分圧電圧を変化させる焼切
作動手段とを含み、機関冷却水温に応じて前記焼
切作動手段による焼切動作を禁止する焼切禁止手
段を有することを特徴とする熱線流量計。 ２ 内燃機関の吸入空気路に設けられた金属線と
該金属線に直列に接続された抵抗とによる第１分
圧回路と、直列接続された複数の抵抗による第２
分圧回路と、前記第１及び第２分圧回路の分圧電
圧の電位差を検出する電位差検出手段と、前記第
１及び第２分圧回路の一端に直列に接続され前記
電位差検出手段の出力信号に応じて作動する能動
素子と、前記第１及び第２分圧回路と前記能動素
子との直列回路の両端間に電圧を供給する電源
と、イグニツシヨンスイツチがオンからオフにな
ると前記金属線の付着物を焼切除去すべく所定期
間前記第２分圧回路の分圧電圧を変化させる焼切
作動手段とを含み、前記イグニツシヨンスイツチ
のオン状態において機関回転数が所定回転数を越
えない限り前記焼切作動手段による焼切動作を禁
止する焼切禁止手段を有することを特徴とする熱
線流量計。[Scope of Claims] 1. A first voltage dividing circuit including a metal wire provided in the intake air passage of an internal combustion engine and a resistor connected in series to the metal wire, and a second voltage dividing circuit including a plurality of resistors connected in series.
a voltage dividing circuit; a potential difference detecting means for detecting a potential difference between the divided voltages of the first and second voltage dividing circuits; and an output of the potential difference detecting means connected in series to one end of the first and second voltage dividing circuits. an active element that operates in response to a signal; a power source that supplies a voltage across a series circuit of the first and second voltage divider circuits and the active element; burn-out operation means for changing the divided voltage of the second voltage dividing circuit for a predetermined period of time in order to burn off and remove deposits on the wire, and prohibit the burn-off operation by the burn-off operation means according to the engine cooling water temperature. A hot wire flow meter characterized by having a burnout prohibition means. 2. A first voltage dividing circuit consisting of a metal wire provided in the intake air path of an internal combustion engine and a resistor connected in series to the metal wire, and a second voltage dividing circuit consisting of a plurality of resistors connected in series.
a voltage dividing circuit; a potential difference detecting means for detecting a potential difference between the divided voltages of the first and second voltage dividing circuits; and an output of the potential difference detecting means connected in series to one end of the first and second voltage dividing circuits. an active element that operates in response to a signal; a power source that supplies a voltage across a series circuit of the first and second voltage divider circuits and the active element; burnout actuating means for changing the divided voltage of the second voltage dividing circuit for a predetermined period of time in order to burn off and remove deposits on the wires, the engine rotational speed is lower than the predetermined rotational speed when the ignition switch is on. A hot-wire flowmeter characterized in that it has a burn-off prohibition means for prohibiting the burn-off operation by the burn-off operation means unless the temperature is exceeded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56186324A JPS5887421A (en) | 1981-11-20 | 1981-11-20 | Hot wire flowmeter for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56186324A JPS5887421A (en) | 1981-11-20 | 1981-11-20 | Hot wire flowmeter for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5887421A JPS5887421A (en) | 1983-05-25 |
| JPH0233966B2 true JPH0233966B2 (en) | 1990-07-31 |
Family
ID=16186340
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56186324A Granted JPS5887421A (en) | 1981-11-20 | 1981-11-20 | Hot wire flowmeter for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5887421A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4665745A (en) * | 1984-05-07 | 1987-05-19 | Nippondenso Co., Ltd. | Heat wire type air flowrate measuring apparatus |
| JPS62249013A (en) * | 1986-04-22 | 1987-10-30 | Japan Electronic Control Syst Co Ltd | Attachment burning-off device of hot-wire type flowmeter in internal combustion engine for automobile |
| JPS63184018A (en) * | 1987-01-27 | 1988-07-29 | Mazda Motor Corp | Control apparatus of heat ray type suction air flowmeter |
| JP3828794B2 (en) | 2001-12-05 | 2006-10-04 | 株式会社日立製作所 | Air flow measurement device |
| DE102019203692A1 (en) * | 2019-03-19 | 2020-09-24 | Robert Bosch Gmbh | Method for the plausibility check of at least one coolant temperature in a drive unit for an electric vehicle and drive unit for an electric vehicle |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5614116A (en) * | 1979-07-06 | 1981-02-10 | Bosch Gmbh Robert | Soaking apparatus for air volume measuring resistance of internal combustion engine |
-
1981
- 1981-11-20 JP JP56186324A patent/JPS5887421A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5614116A (en) * | 1979-07-06 | 1981-02-10 | Bosch Gmbh Robert | Soaking apparatus for air volume measuring resistance of internal combustion engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5887421A (en) | 1983-05-25 |
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