JPH0146008B2 - - Google Patents
Info
- Publication number
- JPH0146008B2 JPH0146008B2 JP57174472A JP17447282A JPH0146008B2 JP H0146008 B2 JPH0146008 B2 JP H0146008B2 JP 57174472 A JP57174472 A JP 57174472A JP 17447282 A JP17447282 A JP 17447282A JP H0146008 B2 JPH0146008 B2 JP H0146008B2
- Authority
- JP
- Japan
- Prior art keywords
- hot wire
- intake air
- hot
- amount
- wire
- 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
Links
- 238000002485 combustion reaction Methods 0.000 claims description 6
- 230000007423 decrease Effects 0.000 description 6
- 239000003990 capacitor Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 241000220317 Rosa Species 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
Description
【発明の詳細な説明】
本発明は内燃機関において吸入空気量を測定す
るために使用される熱線流量計に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot-wire flowmeter used to measure the amount of intake air in an internal combustion engine.
従来の熱線流量計としては、例えば第１図及び
第２図に示すようなものがある。 Examples of conventional hot wire flowmeters include those shown in FIGS. 1 and 2.
第１図を参照し、内燃機関の吸入空気通路１中
に配設される保持リング２に、電気回路と接続さ
れる２本のリード線３と、２本のフツク４とを保
持させ、これらリード線３及びフツク４の先端部
を保持リング２内に位置させてある。そして、保
持リング２内の一対のリード線３の先端部間に、
途中で２つのフツク４に係止させることによりコ
字状にして、熱線５を張設してある。 Referring to FIG. 1, a holding ring 2 disposed in an intake air passage 1 of an internal combustion engine holds two lead wires 3 connected to an electric circuit and two hooks 4. The ends of the lead wire 3 and the hook 4 are located within the retaining ring 2. Then, between the tips of the pair of lead wires 3 in the retaining ring 2,
The hot wire 5 is stretched in a U-shape by being locked with two hooks 4 in the middle.
そして、リード線３と電気回路との接続によ
り、回路的には、第２図に示す如く、熱線５
（Rh）と抵抗R1，R2，R3（R1は温度補償用抵抗、
R2は流量調整用抵抗、R3は基準抵抗）とにより
ブリツジ回路が構成される。 By connecting the lead wire 3 and the electric circuit, the circuit is constructed as shown in FIG.
(Rh) and resistances R 1 , R 2 , R 3 (R 1 is a temperature compensation resistance,
R2 is a flow rate adjustment resistor, R3 is a reference resistor), and a bridge circuit is constructed.
また、このブリツジ回路への供給電流は、抵抗
R2の端子電圧と抵抗R3の端子電圧とに基づき供
給電流制御回路を構成する差動増巾器Op及びト
ランジスタTr1，Tr2を介して制御されるように
なつている。例えば、流速が増大すると、熱線
Rhがより冷却されることによりその抵抗値が減
少するが、このとき抵抗R3の端子電圧が増大し
て、差動増巾器Opの出力が低下し、これにより
トランジスタTr1，Tr2を介してブリツジ回路へ
の供給電流が増大するようになつている。 Also, the current supplied to this bridge circuit is
It is controlled based on the terminal voltage of R 2 and the terminal voltage of resistor R 3 via a differential amplifier Op and transistors Tr 1 and Tr 2 that constitute a supply current control circuit. For example, as the flow rate increases, the hot wire
As Rh is further cooled, its resistance value decreases, but at this time the terminal voltage of resistor R 3 increases and the output of differential amplifier Op decreases, which causes transistors Tr 1 and Tr 2 to The current supplied to the bridge circuit is increased through the bridge circuit.
こうして、流速の変化に対し、熱線Rhの抵抗
値を一定に保つように供給電流を変化させ、その
供給電流すなわち抵抗R3の端子電圧Ｕから流速
を読取るのである。 In this way, the supplied current is changed so as to keep the resistance value of the hot wire Rh constant in response to changes in the flow velocity, and the flow velocity is read from the supplied current, that is, the terminal voltage U of the resistor R3 .
ところで、このような熱線流量計の熱線は通常
100℃以上の一定温度にコントロールされるが、
吸入空気温度が低い場合は、機関停止後（キーオ
フ後）、しばしば熱線表面に水滴が付着し、氷結
することがある。そして、熱線が氷結した状態で
機関を始動して流量計を動作させると、供給電流
制御回路は熱線を一定温度（一定抵抗）にするよ
うに働き、このとき熱線が氷結しているため、大
電流を流して、これを溶かそうとする。 By the way, the hot wire of such a hot wire flowmeter is usually
Although the temperature is controlled at a constant temperature of 100℃ or more,
When the intake air temperature is low, water droplets often adhere to the surface of the hot wire and may freeze after the engine is stopped (after the key is turned off). Then, when the engine is started and the flow meter is operated with the hot wire frozen, the supply current control circuit works to keep the hot wire at a constant temperature (constant resistance). Try to melt it by passing an electric current through it.
よつて、このときに、第３図に示すように熱線
５（Rh）の一部に氷結していない部分があると、
この部分の温度が局部的に上昇し、熱線が溶断し
てしまうことがあつた。 Therefore, at this time, if there is a part of the hot wire 5 (Rh) that is not frozen as shown in Figure 3,
The temperature in this area rose locally, causing the heating wire to melt.
本発明はこのような従来の問題点を解決するこ
とを目的としてなされたもので、始動に際しイグ
ニツシヨンスイツチが閉結されたときに所定の時
間、ブリツジ回路への供給電流を強制的に減少さ
せるように構成し、もつて氷結時の局部的に過熱
による熱線の溶断を防止するようにしたものであ
る。 The present invention has been made with the aim of solving these conventional problems.The present invention forcibly reduces the supply current to the bridge circuit for a predetermined period of time when the ignition switch is closed during starting. This structure prevents the hot wire from melting due to localized overheating during freezing.
以下に本発明の一実施例を第４図によつて説明
する。但し、実施例において従来例（第２図）と
同一部分には同一符号を付して、異なる部分につ
いてのみ説明する。 An embodiment of the present invention will be described below with reference to FIG. However, in the embodiment, the same parts as in the conventional example (FIG. 2) are given the same reference numerals, and only the different parts will be explained.
熱線Rhと基準抵抗R3との接続点（差動増巾器
Opの−側端子）を抵抗R4及びトランジスタTr3
を介してアースしてある。すなわち、基準抵抗
R3に対し、並列に、抵抗R4及びトランジスタTr3
に設けてある。 Connection point between hot wire Rh and reference resistor R3 (differential amplifier
- side terminal of Op) to resistor R4 and transistor Tr3
It is grounded through. That is, the reference resistance
In parallel to R 3 , a resistor R 4 and a transistor Tr 3
It is provided in
そして、トランジスタTr3のベース端子に、イ
グニツシヨンスイツチSwを抵抗R5及びコンデン
サＣを介して接続し、抵抗R5とコンデンサＣと
の接続部を抵抗R6を介してアースしてある。 The ignition switch Sw is connected to the base terminal of the transistor Tr3 via a resistor R5 and a capacitor C, and the connection between the resistor R5 and the capacitor C is grounded via a resistor R6 .
従つて、始動に際し、イグニツシヨンスイツチ
Swがオンとなると、その瞬間からコンデンサＣ
と抵抗R5とのCRタイマにより決る時定数の時間
だけ、スイツチング手段としてのトランジスタ
Tr3が導通し、ブリツジ回路の基準抵抗R3に対し
並列に抵抗R4が入るようになる。 Therefore, when starting, the ignition switch
When Sw turns on, from that moment on, capacitor C
and resistor R 5 for a time constant determined by the CR timer, the transistor as a switching means.
Tr 3 becomes conductive, and a resistor R 4 is inserted in parallel with the reference resistor R 3 of the bridge circuit.
すると、ブリツジ回路のバランスが変化し、基
準抵抗R3に対し並列に入つた抵抗R4の分だけみ
かけ上基準抵抗の抵抗値が減少し、その分熱線
Rhの抵抗値が下がるように制御される。つまり
は、供給電流が減少する。これにより、熱線Rh
に流れる電流が減少し、前述のように氷結時に一
部に氷結していない部分があつても溶断すること
はない。 Then, the balance of the bridge circuit changes, and the apparent resistance value of the reference resistor decreases by the amount of resistor R 4 connected in parallel with the reference resistor R 3 , and the heating wire decreases by that amount.
The Rh resistance value is controlled to decrease. In other words, the supply current decreases. This allows the hot wire Rh
The current flowing through the ice is reduced, and as mentioned above, even if there is a part that is not frozen when it freezes, it will not melt.
尚、このときに熱線流量計の出力（Ｕ／Ub）
は吸入空気量に対応しなくなるが、始動の際の一
時期であり、この熱線流量計の出力に基づいて燃
料噴射量を決定する燃料噴射式の内燃機関では、
通常熱線流量計の起動時にはその出力を読取るこ
となく、別の態様で制御がなされるので、何ら問
題はない。 At this time, the output of the hot wire flowmeter (U/Ub)
Although it no longer corresponds to the amount of intake air, it is a temporary period during startup, and in a fuel injection type internal combustion engine where the fuel injection amount is determined based on the output of this hot wire flowmeter,
Normally, when a hot wire flowmeter is started up, the output is not read and control is performed in a different manner, so there is no problem.
そして、所定時間の後、コンデンサＣの充電が
完了することによりトランジスタTr3が非導通と
なり、正規の状態に戻る。 Then, after a predetermined time, charging of the capacitor C is completed and the transistor Tr3 becomes non-conductive, returning to the normal state.
以上説明したように本発明によれば、イグニツ
シヨンスイツチが閉結されたときに所定の時間、
ブリツジ回路への供給電流を減少させる手段を設
け、熱線の氷結時にも熱線に過大な電流が流れな
いようにしたので、一部氷結していない部分があ
つても溶断することがなくなるという効果が得ら
れる。 As explained above, according to the present invention, when the ignition switch is closed, the
We have provided a means to reduce the current supplied to the bridge circuit to prevent excessive current from flowing through the hot wire even when the hot wire is frozen, which has the effect of preventing it from melting even if there is a part that is not frozen. can get.
第１図は従来例を示す熱線流量計の要部斜視
図、第２図は同上の熱線流量計の回路図、第３図
は同上の熱線流量計の氷結状態の正面図、第４図
は本発明の一実施例を示す熱線流量計の回路図で
ある。
５，Rh……熱線、R1……温度補償用抵抗、R2
……流量調整用抵抗、R3……基準抵抗、Op……
差動増巾器、R4……抵抗、Tr3……トランジス
タ、R5……CRタイマ用の抵抗、Ｃ……CRタイ
マ用のコンデンサ、Sw……イグニツシヨンスイ
ツチ。
Fig. 1 is a perspective view of the main parts of a conventional hot wire flowmeter, Fig. 2 is a circuit diagram of the same hot wire flowmeter, Fig. 3 is a front view of the above hot wire flowmeter in a frozen state, and Fig. 4 is a FIG. 1 is a circuit diagram of a hot wire flowmeter showing an embodiment of the present invention. 5, Rh...Heating wire, R1 ...Temperature compensation resistance, R2
...Resistance for flow rate adjustment, R 3 ...Reference resistance, Op...
Differential amplifier, R4 ...Resistor, Tr3 ...Transistor, R5 ...Resistance for CR timer, C...Capacitor for CR timer, Sw...Ignition switch.
Claims (1)
ツジ回路と、前記熱線の抵抗値を一定にするよう
ブリツジ回路への供給電流を制御する供給電流制
御回路とを備え、その供給電流から吸入空気量を
測定するようにした内燃機関の吸入空気量測定用
熱線流量計において、イグニツシヨンスイツチが
閉結されたときに所定の時間、前記供給電流を減
少させる手段を設けたことを特徴とする内燃機関
の吸入空気量測定用熱線流量計。 ２ 前記手段が、熱線のアース側に直列に接続さ
れる基準抵抗に対し、イグニツシヨンスイツチか
らの信号がCRタイマを介して入力されるスイツ
チング素子を介して、並列に接続される抵抗であ
る特許請求の範囲第１項記載の内燃機関の吸入空
気量測定用熱線流量計。[Scope of Claims] 1. A bridge circuit including a hot wire disposed in an intake air passage, and a supply current control circuit for controlling a current supplied to the bridge circuit so as to maintain a constant resistance value of the hot wire, A hot-wire flowmeter for measuring the amount of intake air of an internal combustion engine that measures the amount of intake air from the supplied current is provided with means for reducing the supplied current for a predetermined period of time when the ignition switch is closed. A hot wire flowmeter for measuring the amount of intake air in an internal combustion engine, characterized by: 2. The means is a resistor connected in parallel to a reference resistor connected in series to the ground side of the hot wire via a switching element into which a signal from the ignition switch is input via a CR timer. A hot-wire flowmeter for measuring the intake air amount of an internal combustion engine according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57174472A JPS5965214A (en) | 1982-10-06 | 1982-10-06 | Hot wire flowmeter for measuring amount of air intake in internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57174472A JPS5965214A (en) | 1982-10-06 | 1982-10-06 | Hot wire flowmeter for measuring amount of air intake in internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5965214A JPS5965214A (en) | 1984-04-13 |
| JPH0146008B2 true JPH0146008B2 (en) | 1989-10-05 |
Family
ID=15979074
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57174472A Granted JPS5965214A (en) | 1982-10-06 | 1982-10-06 | Hot wire flowmeter for measuring amount of air intake in internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5965214A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2516086B2 (en) * | 1990-04-03 | 1996-07-10 | 株式会社ユニシアジェックス | Intake air flow rate measuring device for internal combustion engine |
| JP2007248136A (en) * | 2006-03-14 | 2007-09-27 | Hitachi Ltd | Thermal gas flow rate measuring device |
| JP5397264B2 (en) * | 2010-02-24 | 2014-01-22 | 株式会社デンソー | Heater drive circuit for heat dissipation type flow sensor |
-
1982
- 1982-10-06 JP JP57174472A patent/JPS5965214A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5965214A (en) | 1984-04-13 |
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