JP5513341B2

JP5513341B2 - Flowmeter

Info

Publication number: JP5513341B2
Application number: JP2010228906A
Authority: JP
Inventors: 昌希金子; 徳行鍋島
Original assignee: Aichi Tokei Denki Co Ltd
Current assignee: Aichi Tokei Denki Co Ltd
Priority date: 2010-10-08
Filing date: 2010-10-08
Publication date: 2014-06-04
Anticipated expiration: 2030-10-08
Also published as: JP2012083176A

Description

本発明は、流量計に関する。 The present invention relates to a flow meter.

水道水の流れに応じて回転する羽根車等の回転体の上部に磁石を固設し、この磁石の回転を検出して出力信号を出力するとともに、互いに出力する信号の位相が異なる２つの磁気センサが設けられ、この２つの磁気センサからの出力信号に基づいて、水道水の流量を測定する電子式水道メータがある。 A magnet is fixed to the upper part of a rotating body such as an impeller that rotates in accordance with the flow of tap water, the rotation of this magnet is detected and an output signal is output, and two magnets having different phases of signals output from each other There is an electronic water meter that is provided with sensors and that measures the flow rate of tap water based on output signals from the two magnetic sensors.

磁気抵抗素子を用いた磁気センサを使用した場合、前記磁石が１回転する間に２パルス出力される。この磁気センサを、その出力の位相差が９０°となるように配置し、その２つの磁気センサの出力信号のデューティ比が５０：５０の場合、２つの磁気センサの出力信号は図７のようになる。 When a magnetic sensor using a magnetoresistive element is used, two pulses are output during one rotation of the magnet. When this magnetic sensor is arranged so that the phase difference between its outputs is 90 ° and the duty ratio of the output signals of the two magnetic sensors is 50:50, the output signals of the two magnetic sensors are as shown in FIG. become.

この図７の一方の磁気センサからの出力信号（Ａ相）の立上がりエッジ、又は／及び、立下りエッジにおいて、他方の磁気センサからの出力信号（Ｂ相）の状態（ＨｉｇｈレベルかＬｏｗレベル）から回転方向を判断するとともに、演算動作が行われる。Ａ相の立上がりエッジにおいてＢ相がＨｉｇｈレベル、又は、Ａ相の立ち下がりエッジにおいてＢ相がＬｏｗレベルならば正転、Ａ相の立上がりエッジにおいてＢ相がＬｏｗレベル、又は、Ａ相の立ち下がりエッジにおいてＢ相がＨｉｇｈレベルならば逆転と判断するように構成されている。なおこの正転、逆転の判断は、電子式水道メータの構成等により、逆となる場合もある。 The state of the output signal (B phase) from the other magnetic sensor at the rising edge and / or the falling edge of the output signal (A phase) from one magnetic sensor in FIG. 7 (High level or Low level) The rotation direction is determined from the above and a calculation operation is performed. Forward rotation if B phase is High level at rising edge of A phase or B phase is Low level at falling edge of A phase, B phase is Low level or falling edge of A phase at rising edge of A phase If the B phase is at a high level at the edge, it is determined that the rotation is reversed. The forward / reverse determination may be reversed depending on the configuration of the electronic water meter.

サンプリング方式（時分割方式）の場合には、回転体の回転方向を正しく検知するには、図７におけるＡ相の立上がりからＢ相の立下りまでの時間（Ｔ１）と、Ａ相の立下りからＢ相の立上がりまでの時間（Ｔ３）内に、夫々少なくとも１回ずつサンプリングを行う必要がある。そのため、最低、サンプリングパルスの周波数（単位時間当りのサンプリング回数）は、磁気センサからの出力信号の最大周波数の４倍（単位時間当りの回転体の最大回転数の８倍）とする必要がある。 In the case of the sampling method (time division method), in order to correctly detect the rotation direction of the rotating body, the time from the rise of the A phase to the fall of the B phase (T1) and the fall of the A phase in FIG. In this case, it is necessary to perform sampling at least once each in the time (T3) from the start to the rise of the B phase. Therefore, at a minimum, the frequency of the sampling pulse (number of samplings per unit time) needs to be four times the maximum frequency of the output signal from the magnetic sensor (eight times the maximum number of rotations of the rotating body per unit time). .

しかし、前記電子式水道メータに用いる磁気センサは、その出力信号（方形信号）のデューティ比が５０：５０であることが望ましいが、製造された磁気センサのデューティ比にはバラつきがある。電子式水道メータに用いることができる磁気センサのデューティ比の範囲を広くすることができれば、磁気センサの歩留まりを上げ、コストを低減することができる。 However, it is desirable that the duty ratio of the output signal (square signal) of the magnetic sensor used in the electronic water meter is 50:50, but the duty ratio of the manufactured magnetic sensor varies. If the range of the duty ratio of the magnetic sensor that can be used in the electronic water meter can be widened, the yield of the magnetic sensor can be increased and the cost can be reduced.

仮に、磁気センサを、その出力の位相差が９０°となるように配置し、その２つの磁気センサの出力信号のデューティ比が３０：７０の場合には、２つの磁気センサの出力信号は図８のようになる。この図８において、Ｔ１：Ｔ２：Ｔ３：Ｔ４＝０．５：２．５：４．５：２．５となる。前述のように、サンプリング方式の場合には、図８のＴ１とＴ３の時間内に、少なくとも１回ずつサンプリングする必要がある。そのためには、サンプリングパルスの周波数を、最低、磁気センサからの出力信号の最大周波数の２０倍（単位時間当りの回転体の最大回転数の４０倍）とする必要がある。このように、使用できる磁気センサのデューティ比の範囲を広くするほど、そのデューティ比においても、回転方向を正確に検知するには、サンプリングパルスの周波数を高くする必要が生じ、それとともに消費電力も大きくなってしまうという問題がある。 If the magnetic sensors are arranged so that the phase difference between the outputs is 90 °, and the duty ratio of the output signals of the two magnetic sensors is 30:70, the output signals of the two magnetic sensors are It becomes like 8. In FIG. 8, T1: T2: T3: T4 = 0.5: 2.5: 4.5: 2.5. As described above, in the case of the sampling method, it is necessary to sample at least once within the times T1 and T3 in FIG. For this purpose, the frequency of the sampling pulse must be at least 20 times the maximum frequency of the output signal from the magnetic sensor (40 times the maximum number of rotations of the rotating body per unit time). In this way, the wider the range of the duty ratio of the magnetic sensor that can be used, the higher the sampling pulse frequency is required to accurately detect the rotational direction even at that duty ratio, and the power consumption is also reduced. There is a problem that it gets bigger.

この消費電力を減らす方法として、回転体の回転数が一定以上となった場合には、回転方向が変化せず継続しているものとして、回転方向の判別を行わず、直前に判別した回転方向を用いて流量等を演算するようにした流量計が知られている（特許文献１参照）。 As a method of reducing this power consumption, when the rotational speed of the rotating body exceeds a certain value, it is assumed that the rotation direction has not changed, and the rotation direction is determined without performing the rotation direction determination. There has been known a flow meter that calculates a flow rate using a sensor (see Patent Document 1).

この特許文献１においては、高速回転時においては、一方の磁気センサからの出力信号のレベルの変化を検知できればよく、全ての回転域において、回転体の回転方向の判別を行う場合と比較して、サンプリング周波数を低くすることができ消費電力を低く抑えることができる。 In this Patent Document 1, it is only necessary to detect a change in the level of the output signal from one magnetic sensor during high-speed rotation, and compared with the case where the rotation direction of the rotating body is determined in all rotation regions. The sampling frequency can be lowered and the power consumption can be kept low.

特開平３−２０６９１７号公報Japanese Patent Laid-Open No. 3-206917

前記特許文献１の流量計において、サンプリングを行った直後に、回転体が直前のサンプリング時の回転方向とは逆方向に回転するとともに、一気に回転体の回転数が、所定値以上となってしまった場合には、その後、回転体の回転数が所定値以下となるまでの間は、回転体の回転方向の判別を行わないため、高速回転時の回転方向と、流量等の算出に使用している回転方向とは異なってしまい、正確な流量を測定できない虞がある。 In the flow meter of Patent Document 1, immediately after sampling, the rotating body rotates in a direction opposite to the rotating direction at the time of the previous sampling, and the rotational speed of the rotating body immediately exceeds a predetermined value. In this case, the rotational direction of the rotating body is not discriminated until the rotational speed of the rotating body falls below a predetermined value. Therefore, there is a possibility that the accurate flow rate cannot be measured.

そこで、本発明は、使用できる磁気センサのデューティ比の範囲を広くした場合においても消費電力を低く抑えるとともに、高速回転時においても回転体の回転方向を正しく判別できる流量計を提供することを目的とするものである。 Accordingly, an object of the present invention is to provide a flow meter that can reduce power consumption even when the duty ratio range of a magnetic sensor that can be used is widened, and that can correctly determine the direction of rotation of a rotating body even during high-speed rotation. It is what.

前記の課題を解決するために、請求項１記載の発明は、流体の流れに応じて回転する回転体とともに回転する磁石の回転を検出して方形波信号として出力し、その出力が互いに位相差を有するように配置された第１の磁気センサと第２の磁気センサと、
前記２つの磁気センサに間欠的に所定時間ずつ電源を供給して駆動させる駆動回路と、
前記駆動回路から磁気センサへの電源供給時における前記第１の磁気センサの出力を記憶する第１記憶部と、前記駆動回路から磁気センサへの電源供給時における前記第２の磁気センサの出力を記憶する第２記憶部と、
第１記憶部からの出力をカウント信号、第２記憶部からの出力を回転方向信号とする第１の状態と、第２記憶部からの出力をカウント信号、第１記憶部からの出力を回転方向信号とする第２の状態とを切替える切替部と、
前記カウント信号の立上がりエッジ、又は／及び、カウント信号の立下がりエッジの際の前記回転方向信号の状態により、加算動作又は減算動作を行なう演算部と、を有し、
前記演算部からの切替信号により、前記第１の状態と第２の状態とを切替えるようにしたことを特徴とする流量計である。 In order to solve the above-mentioned problem, the invention according to claim 1 detects the rotation of the rotating magnet together with the rotating body rotating in accordance with the flow of the fluid and outputs it as a square wave signal, and the outputs are mutually different in phase difference. A first magnetic sensor and a second magnetic sensor arranged to have
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A first storage unit that stores an output of the first magnetic sensor when power is supplied from the drive circuit to the magnetic sensor, and an output of the second magnetic sensor when power is supplied from the drive circuit to the magnetic sensor. A second storage unit for storing;
The first state where the output from the first storage unit is the count signal, the output from the second storage unit is the rotation direction signal, the output from the second storage unit is the count signal, and the output from the first storage unit is rotated A switching unit for switching between the second state as the direction signal;
An arithmetic unit that performs an addition operation or a subtraction operation depending on the state of the rotation direction signal at the rising edge of the count signal or / and the falling edge of the count signal;
The flowmeter is characterized in that the first state and the second state are switched by a switching signal from the arithmetic unit.

請求項２記載の発明は、流体の流れに応じて回転する回転体とともに回転する磁石の回転を検出して方形波信号として出力し、その出力が互いに位相差を有するように配置された第１の磁気センサと第２の磁気センサと、
前記２つの磁気センサに間欠的に所定時間ずつ電源を供給して駆動する駆動回路と、
前記駆動回路から磁気センサへの電源供給時における前記２つの磁気センサの一方の出力を記憶する第１記憶部と、他方の出力を記憶する第２記憶部と、
第１の磁気センサからの出力を第１記憶部へ入力し、第２の磁気センサからの出力を第２記憶部へ入力する第１の状態と、第１の磁気センサからの出力を第２記憶部へ入力し、第２の磁気センサからの出力を第１記憶部へ入力する第２の状態とを切替える切替部と、
第１記憶部からの出力と第２記憶部からの出力のうち一方をカウント信号とし、他方を回転方向信号として、前記カウント信号の立上がりエッジ、又は／及び、カウント信号の立下がりエッジの際の前記回転方向信号の状態により、加算動作又は減算動作を行なう演算部と、を有し、
前記演算部からの切替信号により、前記第１の状態と第２の状態とを切替えるようにしたことを特徴とする流量計である。 In the first aspect of the invention, the rotation of the magnet that rotates together with the rotating body that rotates according to the flow of the fluid is detected and output as a square wave signal, and the outputs are arranged so as to have a phase difference from each other. A magnetic sensor and a second magnetic sensor,
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A first storage for storing one output of the two magnetic sensors at the time of power supply from the drive circuit to the magnetic sensor; a second storage for storing the other output;
The first state in which the output from the first magnetic sensor is input to the first storage unit and the output from the second magnetic sensor is input to the second storage unit, and the output from the first magnetic sensor is the second A switching unit that switches between a second state of inputting to the storage unit and inputting an output from the second magnetic sensor to the first storage unit;
One of the output from the first storage unit and the output from the second storage unit is used as a count signal, and the other is used as a rotation direction signal. At the rising edge of the count signal or / and at the falling edge of the count signal A calculation unit that performs an addition operation or a subtraction operation depending on the state of the rotation direction signal;
The flowmeter is characterized in that the first state and the second state are switched by a switching signal from the arithmetic unit.

請求項３記載の発明は、請求項１又は２記載の流量計において、カウント信号の立上がりエッジ、又は／及び、カウント信号の立下がりエッジの際の前記回転方向信号の状態により、回転体の回転方向の判別を行い、
回転体の回転数が所定値以上の場合において、回転体の回転方向の判別で、正転と逆転が混在しているときに、前記第１の状態と第２の状態とを切替えるようにしたことを特徴とするものである。 According to a third aspect of the present invention, in the flowmeter according to the first or second aspect, the rotation of the rotating body is determined according to the state of the rotation direction signal at the rising edge of the count signal and / or the falling edge of the count signal. Determine the direction,
When the rotational speed of the rotating body is greater than or equal to a predetermined value, when the rotation direction of the rotating body is determined, when the forward rotation and the reverse rotation are mixed, the first state and the second state are switched. It is characterized by this.

請求項４記載の発明は、請求項１又は２記載の流量計において、カウント信号の立上がりエッジ、又は／及び、カウント信号の立下がりエッジの際の前記回転方向信号の状態により、回転体の回転方向の判別を行い、
回転体の回転数が、所定値以上の場合において、回転体の回転方向の判別が、直前の判別と異なるときに、前記第１の状態と第２の状態とを切替えるようにしたことを特徴とするものである。 According to a fourth aspect of the present invention, in the flowmeter according to the first or second aspect , the rotation of the rotating body is determined according to the state of the rotation direction signal at the rising edge of the count signal and / or the falling edge of the count signal. Determine the direction,
When the rotational speed of the rotating body is equal to or greater than a predetermined value, the first state and the second state are switched when the rotational direction of the rotating body is different from the previous determination. It is what.

請求項５記載の発明は、流体の流れに応じて回転する回転体とともに回転する磁石の回転を検出し、その出力信号が互いに位相差を有するように配置された第１の磁気センサと第２の磁気センサと、
前記２つの磁気センサに間欠的に所定時間ずつ電源を供給して駆動する駆動回路と、
第１の磁気センサからの出力信号と、第２の磁気センサからの出力信号から回転体の回転方向の判別を行って、加算動作又は減算動作を行なう演算部と、を有し、
前記駆動回路は、前記磁気センサへ第１駆動間隔で電源を供給し、所定間隔で所定の時間の間は、該第１駆動間隔より短い第２駆動間隔で磁気センサへ電源を供給し、
前記回転体の単位時間当りの回転数が、所定値より大きい場合には、前記第２駆動間隔時のみ回転体の回転方向の判別を行い、第１駆動間隔時の場合は回転体の回転方向の判別を行わず、直前に判別した回転方向に基づいて、前記加算動作又は減算動作を行なうことを特徴とする流量計である。 According to a fifth aspect of the present invention, the first magnetic sensor and the second magnetic sensor are arranged so that the rotation of the magnet that rotates together with the rotating body that rotates according to the fluid flow is detected, and the output signals thereof have a phase difference from each other. Magnetic sensor of
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval, and supplies power to the magnetic sensor at a second drive interval shorter than the first drive interval for a predetermined time at a predetermined interval;
When the number of rotations of the rotating body per unit time is larger than a predetermined value, the rotation direction of the rotating body is determined only at the second driving interval, and at the first driving interval, the rotating direction of the rotating body is determined. The flowmeter is characterized in that the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before the determination.

請求項６記載の発明は、流体の流れに応じて回転する回転体とともに回転する磁石の回転を検出し、その出力信号が互いに位相差を有するように配置された第１の磁気センサと第２の磁気センサと、
前記２つの磁気センサに間欠的に所定時間ずつ電源を供給して駆動する駆動回路と、
第１の磁気センサからの出力信号と、第２の磁気センサからの出力信号から回転体の回転方向の判別を行って、加算動作又は減算動作を行なう演算部と、を有し、
前記駆動回路は、前記磁気センサへ第１駆動間隔で電源を供給し、前記回転体の単位時間当りの回転数が、所定値より大きい場合には、所定間隔で所定の時間の間は、該第１駆動間隔より短い第２駆動間隔で磁気センサへ電源を供給し、
前記回転体の単位時間当りの回転数が、所定値より大きい場合には、前記第２駆動間隔時のみ回転体の回転方向の判別を行い、第１駆動間隔時の場合は回転体の回転方向の判別を行わず、直前に判別した回転方向に基づいて、前記加算動作又は減算動作を行なうことを特徴とする流量計である。 According to a sixth aspect of the present invention, the first magnetic sensor and the second magnetic sensor are arranged such that the rotation of the magnet rotating together with the rotating body rotating according to the fluid flow is detected and the output signals thereof have a phase difference from each other. Magnetic sensor of
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval, and when the number of rotations of the rotating body per unit time is larger than a predetermined value, Supplying power to the magnetic sensor at a second driving interval shorter than the first driving interval;
When the number of rotations of the rotating body per unit time is larger than a predetermined value, the rotation direction of the rotating body is determined only at the second driving interval, and at the first driving interval, the rotating direction of the rotating body is determined. The flowmeter is characterized in that the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before the determination.

請求項７記載の発明は、流体の流れに応じて回転する回転体とともに回転する磁石の回転を検出し、その出力信号が互いに位相差を有するように配置された第１の磁気センサと第２の磁気センサと、
前記２つの磁気センサに間欠的に所定時間ずつ電源を供給して駆動する駆動回路と、
第１の磁気センサからの出力信号と、第２の磁気センサからの出力信号から回転体の回転方向の判別を行って、加算動作又は減算動作を行なう演算部と、を有し、
前記駆動回路は、前記磁気センサへ第１駆動間隔で電源を供給し、
前記回転体の単位時間当りの回転数が、所定値より大きくなった場合には、回転体の回転方向の判別結果において、その判別した回転方向が、所定の回数以上同じとなるまでの間は、該第１駆動間隔より短い第２駆動間隔で磁気センサへ電源を供給し、それ以後、前記回転体の単位時間当りの回転数が、所定値以下となるまで、回転体の回転方向の判別を行わず、直前に判別した回転方向に基づいて、前記加算動作又は減算動作を行なうことを特徴とする流量計である。 According to the seventh aspect of the present invention, the first magnetic sensor and the second magnetic sensor are arranged so that the rotation of the magnet rotating together with the rotating body rotating according to the fluid flow is detected and the output signals thereof have a phase difference from each other. Magnetic sensor of
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval;
When the number of rotations per unit time of the rotating body is greater than a predetermined value, in the determination result of the rotating direction of the rotating body, until the determined rotating direction is the same as a predetermined number of times. The power source is supplied to the magnetic sensor at a second driving interval shorter than the first driving interval, and thereafter, the rotational direction of the rotating body is determined until the rotational speed per unit time of the rotating body becomes a predetermined value or less. The flowmeter is characterized in that the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before without performing the operation.

請求項８記載の発明は、流体の流れに応じて回転する回転体とともに回転する磁石の回転を検出し、その出力信号が互いに位相差を有するように配置された第１の磁気センサと第２の磁気センサと、
前記２つの磁気センサに間欠的に所定時間ずつ電源を供給して駆動する駆動回路と、
第１の磁気センサからの出力信号と、第２の磁気センサからの出力信号から回転体の回転方向の判別を行って、加算動作又は減算動作を行なう演算部と、を有し、
前記駆動回路は、前記磁気センサへ第１駆動間隔で電源を供給し、
前記回転体の単位時間当りの回転数が、所定値より大きくなった場合には、所定時間、該第１駆動間隔より短い第２駆動間隔で磁気センサへ電源を供給し、それ以後、前記回転体の単位時間当りの回転数が、所定値以下となるまで、回転体の回転方向の判別を行わず、直前に判別した回転方向に基づいて、前記加算動作又は減算動作を行なうことを特徴とする流量計である。 According to the eighth aspect of the present invention, the first magnetic sensor and the second magnetic sensor are arranged so that the rotation of the magnet rotating together with the rotating body rotating in accordance with the fluid flow is detected and the output signals thereof have a phase difference from each other. Magnetic sensor of
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval;
When the number of rotations of the rotating body per unit time is greater than a predetermined value, power is supplied to the magnetic sensor at a second driving interval shorter than the first driving interval for a predetermined time, and thereafter the rotation is performed. Until the number of rotations per unit time of the body becomes a predetermined value or less, the rotation direction of the rotating body is not determined, and the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before. This is a flow meter.

請求項９記載の発明は、請求項５乃至８の何れか１項に記載の流量計において、一方の磁気センサからの出力をカウント信号とし、他方の磁気センサからの出力を回転方向信号として回転体の回転方向の判別を行い、
前記回転体の回転方向の判別を行わない場合には、回転方向信号として用いる磁気センサへの電源を供給しないことを特徴とするものである。 According to a ninth aspect of the present invention, in the flowmeter according to any one of the fifth to eighth aspects, the output from one magnetic sensor is used as a count signal, and the output from the other magnetic sensor is used as a rotation direction signal. Determine the direction of body rotation,
When the rotation direction of the rotating body is not discriminated, power is not supplied to the magnetic sensor used as the rotation direction signal.

請求項１乃至４記載の発明によれば、切替部により、カウント信号又は回転方向信号として用いる、第１と第２の磁気センサからの出力を入れ替えることできるようにしたことにより、サンプリングパルスの周波数をそれほど上げることなく、回転体の回転方向の判別を精度良く行え、低消費電力とすることができる。 According to the first to fourth aspects of the present invention, the output of the first and second magnetic sensors used as the count signal or the rotation direction signal can be exchanged by the switching unit, so that the frequency of the sampling pulse is changed. Without increasing so much, the direction of rotation of the rotating body can be determined with high accuracy and low power consumption can be achieved.

また、磁気センサの出力信号のデューティ比が悪い場合にも、前記従来技術のように、サンプリングパルスの周波数を大幅に上げることなく、デューティ比が５０：５０の場合とほぼ同じサンプリングパルスの周波数で対応することができるため、消費電力をほとんど上げることなく、広範囲の磁気センサを使用することができるため、磁気センサの歩留まりを上げ、コスト低減を図ることができる。 In addition, even when the duty ratio of the output signal of the magnetic sensor is poor, the sampling pulse frequency is substantially the same as when the duty ratio is 50:50, without significantly increasing the sampling pulse frequency as in the prior art. Therefore, it is possible to use a wide range of magnetic sensors with almost no increase in power consumption. Therefore, the yield of the magnetic sensors can be increased and the cost can be reduced.

請求項５乃至９記載の発明によれば、回転体の単位時間当りの回転数が、所定値より大きくなった場合に、第１駆動間隔より短い第２駆動間隔で、所定間隔、又は、所定時間、又は、所定回数の回転方向の判別を行うことにより、前記特許文献１のような回転方向の誤検知を防止し、消費電力をそれほど増加することなく、回転体の回転方向の判別を精度良く行える。 According to the fifth to ninth aspects of the present invention, when the number of rotations of the rotating body per unit time is larger than a predetermined value, the second driving interval is shorter than the first driving interval, the predetermined interval, or the predetermined interval. By discriminating the rotation direction for a time or a predetermined number of times, it is possible to prevent erroneous detection of the rotation direction as in Patent Document 1 and to accurately determine the rotation direction of the rotating body without significantly increasing power consumption. Can do well.

また、磁気センサの出力信号のデューティ比が悪い場合にも、前記従来技術と比較して、高周波数のサンプリングパルスで磁気センサに電源を供給する時間を減らし、消費電力をあまり増加することなく、広範囲の磁気センサを使用することができ、磁気センサの歩留まりを上げ、コスト低減を図ることができる。 In addition, even when the duty ratio of the output signal of the magnetic sensor is bad, compared with the conventional technique, the time for supplying power to the magnetic sensor with a high frequency sampling pulse is reduced, and the power consumption is not increased so much. A wide range of magnetic sensors can be used, the yield of magnetic sensors can be increased, and costs can be reduced.

本発明の実施例１の流量計における回転体と計測部との関係を示す図。The figure which shows the relationship between the rotary body and measurement part in the flowmeter of Example 1 of this invention. 本発明の実施例１の流量計の全体構成を示すブロック図。1 is a block diagram illustrating an overall configuration of a flow meter according to a first embodiment of the present invention. 本実施例１を説明するための磁気センサからの出力波形。The output waveform from the magnetic sensor for demonstrating the present Example 1. FIG. 本実施例１を説明するための磁気センサからの出力波形。The output waveform from the magnetic sensor for demonstrating the present Example 1. FIG. 本発明の実施例２の流量計の全体構成を示すブロック図。The block diagram which shows the whole structure of the flowmeter of Example 2 of this invention. 本発明の実施例３の流量計の全体構成を示すブロック図。The block diagram which shows the whole structure of the flowmeter of Example 3 of this invention. ２つの磁気センサの出力信号のデューティ比が５０：５０の場合の出力波形。The output waveform when the duty ratio of the output signals of the two magnetic sensors is 50:50. ２つの磁気センサの出力信号のデューティ比が３０：７０の場合の出力波形。The output waveform when the duty ratio of the output signals of the two magnetic sensors is 30:70.

本発明の流量計は、水道水等の液体や、ガス等の気体の被計測流体の流れに応じて、羽根車等の回転体が回転し、この回転体の回転を磁気センサで検出し、該磁気センサからの出力信号に基づいて流量を計測する流量計である。この流量計は、水道メータやガスメータに用いることができ、以下の実施例においては、水道メータに適用した実施例に基づいて説明する。 The flow meter of the present invention rotates a rotating body such as an impeller according to the flow of a fluid to be measured such as a liquid such as tap water or a gas, and detects the rotation of the rotating body with a magnetic sensor. It is a flow meter that measures a flow rate based on an output signal from the magnetic sensor. This flow meter can be used for a water meter or a gas meter, and the following embodiments will be described based on an embodiment applied to a water meter.

図１乃至図４は本発明の実施例１を示す。
図２は、本実施例１の流量計の全体構成を示すブロック図である。 1 to 4 show Embodiment 1 of the present invention.
FIG. 2 is a block diagram illustrating the overall configuration of the flow meter of the first embodiment.

水道メータは、内部に図１に示すような回転体である羽根車１を備え、該羽根車１の上端部には、磁石２が固設されている。該磁石２は、羽根車１の軸方向と直交する方向に磁化され、すなわち、１つのＮ極と１つのＳ極とが、羽根車１の軸の周方向において１８０度離れて設けられている。 The water meter includes an impeller 1 that is a rotating body as shown in FIG. 1, and a magnet 2 is fixed to the upper end of the impeller 1. The magnet 2 is magnetized in a direction orthogonal to the axial direction of the impeller 1, that is, one N pole and one S pole are provided 180 degrees apart in the circumferential direction of the impeller 1 axis. .

前記羽根車１の上方近傍には、計測部３が設けられている。該計測部３内には、第１の磁気センサ４と，第２の磁気センサ５が備えられている。２つの磁気センサ４，５は、磁気抵抗素子を用いた磁気センサであり、前記磁石２が羽根車１とともに回転する際の磁界の変化を磁気抵抗素子で検出して、例えば図３に示すような、方形波信号として出力する。また、磁気センサ４，５は、羽根車１が１回転する間に、２周期（２パルス）の方形波信号を出力する。２つの磁気センサ４，５からの出力信号が、互いに電気的に９０度位相がずれるように、２つの磁気センサ４，５は配設されている。 A measuring unit 3 is provided near the upper portion of the impeller 1. The measurement unit 3 includes a first magnetic sensor 4 and a second magnetic sensor 5. The two magnetic sensors 4 and 5 are magnetic sensors using a magnetoresistive element, and the change of the magnetic field when the magnet 2 rotates with the impeller 1 is detected by the magnetoresistive element. For example, as shown in FIG. It outputs as a square wave signal. The magnetic sensors 4 and 5 output a square wave signal of two periods (two pulses) while the impeller 1 makes one rotation. The two magnetic sensors 4 and 5 are arranged so that the output signals from the two magnetic sensors 4 and 5 are electrically 90 degrees out of phase with each other.

駆動回路６は、２つの磁気センサ４，５に、所定の間隔で間欠的に所定の短時間ずつ電源を供給して、磁気センサ４，５を駆動する。本実施例においては、駆動回路６から、周波数５１２Ｈｚ、パルス幅が、その周期より大幅に短い（実施例では、２０μＳ）のサンプリングパルスを出力し、該サンプリングパルスが磁気センサ４，５の電源電圧として印加されて磁気センサ４，５を駆動する。 The drive circuit 6 drives the magnetic sensors 4 and 5 by supplying power to the two magnetic sensors 4 and 5 intermittently at predetermined intervals for a predetermined short time. In this embodiment, the driving circuit 6 outputs a sampling pulse having a frequency of 512 Hz and a pulse width that is significantly shorter than the period (in the embodiment, 20 μS), and the sampling pulse is the power supply voltage of the magnetic sensors 4 and 5. To drive the magnetic sensors 4 and 5.

前記第１の磁気センサ４からの出力が、第１記憶部７に入力され、第２の磁気センサ５からの出力が、第２記憶部８に入力されている。２つの記憶部７，８には、駆動回路６から磁気センサ４，５への電源供給と同じタイミングで記憶タイミング信号が入力され、記憶部７，８は、記憶タイミング信号の入力の際の磁気センサ４，５の出力の状態（ＨｉｇｈレベルかＬｏｗレベル）を記憶し、記憶した状態を切替部９へ出力する。 An output from the first magnetic sensor 4 is input to the first storage unit 7, and an output from the second magnetic sensor 5 is input to the second storage unit 8. A storage timing signal is input to the two storage units 7 and 8 at the same timing as the power supply from the drive circuit 6 to the magnetic sensors 4 and 5, and the storage units 7 and 8 are magnetic when the storage timing signal is input. The output state (High level or Low level) of the sensors 4 and 5 is stored, and the stored state is output to the switching unit 9.

前記切替部９は、第１記憶部７からの出力をカウント信号、第２記憶部８からの出力を回転方向信号として演算部１０へ入力する第１の状態と、第１記憶部７からの出力を回転方向信号、第２記憶部８からの出力をカウント信号として演算部１０へ入力する第２の状態とに切替えることができるようになっている。 The switching unit 9 includes a first state in which the output from the first storage unit 7 is input to the arithmetic unit 10 as a count signal and the output from the second storage unit 8 is a rotation direction signal. The output can be switched to the second state in which the output is input to the calculation unit 10 as the rotation direction signal and the output from the second storage unit 8 as the count signal.

前記演算部１０は、カウント信号の立上がりエッジ（ＬｏｗレベルからＨｉｇｈレベルへの反転時）と、立下がりエッジ（ＨｉｇｈレベルからＬｏｗレベルへの反転時）における回転方向信号の状態（Ｈｉｇｈレベル又はＬｏｗレベル）から、羽根車１の回転方向を判別して、羽根車１の回転方向が正転と判別した場合は、羽根車１／４回転に相当する値を記憶していた直前の積算値に加算し、羽根車１の回転方向が逆転と判別した場合は、羽根車１／４回転に相当する値を、記憶していた直前の積算値から減算し、新しい積算値を記憶するとともに、図示しない表示部に新しい積算値から流量等を演算し更新表示する。 The arithmetic unit 10 determines the state of the rotation direction signal (High level or Low level) at the rising edge (when inversion from Low level to High level) and the falling edge (when inversion from High level to Low level) of the count signal. ), The rotational direction of the impeller 1 is determined, and when the rotational direction of the impeller 1 is determined to be normal rotation, the value corresponding to the 1/4 rotation of the impeller is added to the previous integrated value. When it is determined that the rotation direction of the impeller 1 is reverse rotation, a value corresponding to ¼ rotation of the impeller 1 is subtracted from the previous integrated value stored, a new integrated value is stored, and not shown. The display unit calculates and updates the flow rate from the new integrated value.

前記演算部１０は、所定時間（本実施例では３．６秒間）における前記積算値の変化から羽根車１の単位時間当りの回転数を演算するようになっている。この単位時間当りの回転数が、所定値（本実施例においては、カウント信号の周波数が２０Ｈｚ、すなわち、羽根車１の回転数が１０回転／ｓ）より大きいときに、羽根車１の回転方向の判別が、直前に行った回転方向の判別結果と異なる場合には、羽根車１の回転方向が安定しないとして、切替え信号を前記切替部９に出力し、切替部９は他方の状態へと切替える。すなわち、第１の状態の場合には第２の状態に、第２の状態の場合には第１の状態に切替えるようになっている。 The computing unit 10 computes the rotational speed per unit time of the impeller 1 from the change of the integrated value in a predetermined time (3.6 seconds in this embodiment). When the rotational speed per unit time is greater than a predetermined value (in this embodiment, the frequency of the count signal is 20 Hz, that is, the rotational speed of the impeller 1 is 10 revolutions / s), the rotational direction of the impeller 1 Is different from the determination result of the rotation direction performed immediately before, the rotation direction of the impeller 1 is not stable, and a switching signal is output to the switching unit 9, and the switching unit 9 is switched to the other state. Switch. That is, the first state is switched to the second state, and the second state is switched to the first state.

図３は、２つの磁気センサ４，５の出力信号のデューティ比が３０：７０で、第１記憶部７からの出力信号をカウント信号と、第２記憶部８からの出力信号を回転方向信号として用い、［１］〜［１０］のときに、演算部１０からタイミング信号が入力されてサンプリングを行った場合を示す。羽根車１の回転方向の判別は、カウント信号におけるレベルが反転した際、この図３においては、［３］、［５］、［８］、［１０］において行われ、その判別結果は、［３］は逆転、［５］は正転、［８］は正転、［１０］は正転と判別される。しかし、［２］〜［３］の間における第１磁気センサ４からの出力信号における立上がりエッジの際、回転方向信号はＨｉｇｈレベルであり、羽根車１の正しい回転方向は正転であり、［３］においては、羽根車１の回転方向が正しく判別されていないことが分る。なお、羽根車１の回転方向の判別としては、カウント信号の立上がりエッジにおいて回転方向信号がＨｉｇｈレベル、又は、カウント信号の立ち下がりにおいて回転方向信号がＬｏｗレベルならば正転と判別し、カウント信号の立上がりエッジにおいて回転方向信号がＬｏｗレベル、又は、カウント信号の立ち下がりエッジにおいて回転方向信号がＨｉｇｈレベルならば逆転と判別するようになっている。 In FIG. 3, the duty ratio of the output signals of the two magnetic sensors 4 and 5 is 30:70, the output signal from the first storage unit 7 is the count signal, and the output signal from the second storage unit 8 is the rotation direction signal. In the case of [1] to [10], a timing signal is input from the calculation unit 10 and sampling is performed. The determination of the rotation direction of the impeller 1 is performed in [3], [5], [8], [10] in FIG. 3 when the level in the count signal is reversed. 3] is determined as reverse rotation, [5] is determined as normal rotation, [8] is determined as normal rotation, and [10] is determined as normal rotation. However, at the rising edge of the output signal from the first magnetic sensor 4 between [2] to [3], the rotation direction signal is at a high level, and the correct rotation direction of the impeller 1 is normal rotation. 3], it can be seen that the rotational direction of the impeller 1 is not correctly determined. The rotation direction of the impeller 1 is determined as normal rotation if the rotation direction signal is at a high level at the rising edge of the count signal or if the rotation direction signal is at the low level at the falling edge of the count signal. If the rotation direction signal is at the low level at the rising edge of the signal or the rotation direction signal is at the high level at the falling edge of the count signal, it is determined that the rotation is reverse.

この、図３におけるカウント信号と回転方向信号を入れ替えると、すなわち、第２記憶部８からの出力信号をカウント信号、第１記憶部７からの出力信号を回転方向信号とすると、図４に示す状態となる。この図４においては、［２］、［３］、［７］、［９］全てにおいて正転と判別される。なお、羽根車１の回転方向の判別としては、図３とは逆に、カウント信号の立上がりエッジにおいて回転方向信号がＬｏｗレベル、又は、カウント信号の立ち下がりエッジにおいて回転方向信号がＨｉｇｈレベルならば正転と判別し、カウント信号の立上がりエッジにおいて回転方向信号がＨｉｇｈレベル、又は、カウント信号の立ち下がりエッジにおいて回転方向信号がＬｏｗレベルならば逆転と判別するようになっている。 When the count signal and the rotation direction signal in FIG. 3 are exchanged, that is, when the output signal from the second storage unit 8 is the count signal and the output signal from the first storage unit 7 is the rotation direction signal, FIG. It becomes a state. In FIG. 4, all of [2], [3], [7], and [9] are determined to be normal rotations. Note that the rotation direction of the impeller 1 is determined in contrast to FIG. 3 if the rotation direction signal is at the low level at the rising edge of the count signal or the rotation direction signal is at the high level at the falling edge of the count signal. When the rotation direction signal is High level at the rising edge of the count signal or when the rotation direction signal is Low level at the falling edge of the count signal, it is determined that the rotation is reverse.

本実施例では、羽根車１の単位時間当りの回転数が、所定値以上の高回転において、羽根車１の回転方向が変わることがないため、演算部１０は、高回転において、図３のように、正転と逆転が混在している場合には、羽根車１の回転方向の判別が安定しないとして判別し、切替部９により第１と第２の状態を切替えるようになっている。これにより、回転方向の誤検知を防止することができる。 In the present embodiment, since the rotational speed of the impeller 1 does not change when the rotational speed per unit time of the impeller 1 is higher than a predetermined value, the calculation unit 10 does not change the rotation direction of FIG. Thus, when the normal rotation and the reverse rotation are mixed, it is determined that the determination of the rotation direction of the impeller 1 is not stable, and the switching unit 9 switches between the first and second states. Thereby, erroneous detection of the rotation direction can be prevented.

従来であれば、図３の［３］の誤検知を無くすためには、サンプリング間隔をより短くする（サンプリングパルスの周波数を上げる）必要があるが、本実施例は、サンプリングパルスの周波数を上げることなく、カウント信号と回転方向信号に用いる信号を、一方の記憶部７（８）からの出力信号を、他方の記憶部８（７）からの出力信号に入れ替えるのみで、回転方向の誤検知を防止することができる。 Conventionally, in order to eliminate the false detection of [3] in FIG. 3, it is necessary to shorten the sampling interval (increase the frequency of the sampling pulse), but this embodiment increases the frequency of the sampling pulse. Without using the count signal and the rotation direction signal, the output signal from one storage unit 7 (8) is replaced with the output signal from the other storage unit 8 (7). Can be prevented.

前記従来技術では、図８のＴ１、と、Ｔ３の間に、夫々少なくとも１回サンプリングをする必要があるが、本実施例は、第１と２記憶部７，８からの出力信号を入れ替えるようにしたことにより、Ｔ１又はＴ２、と、Ｔ３又はＴ４の夫々の間に少なくとも１回サンプリングすればよくなり、サンプリングパルスの周波数を、最低、磁気センサ４，５からの出力信号における最大周波数の４倍（単位時間当りの回転体の最大回転数の８倍）とすればよい。本実施例においては、羽根車１の最大回転数を５０回転／ｓ、磁気センサ４，５からの出力信号の最大周波数では１００Ｈｚとし、そのサンプリングパルスの周波数を５１２Ｈｚとした。このように、従来であれば、２つの磁気センサの出力信号のデューティ比が３０：７０の場合には、サンプリングパルスの周波数を最低２０００Ｈｚに設定する必要があるところを、本実施例では、羽根車１の回転方向の誤検知をすることなく、サンプリングパルスの周波数を５１２Ｈｚとすることができ、消費電力を大幅に減らし、電池寿命をのばすことができる。また、全ての回転域において、羽根車１の回転方向の判別を行うため、前記特許文献１のような回転方向の誤検知を防止することができる。 In the prior art, it is necessary to sample at least once between T1 and T3 in FIG. 8, but in this embodiment, the output signals from the first and second storage units 7 and 8 are exchanged. As a result, it is only necessary to sample at least once during each of T1 or T2 and T3 or T4. The frequency of the sampling pulse is at least 4 of the maximum frequency in the output signals from the magnetic sensors 4 and 5. It may be doubled (8 times the maximum number of rotations of the rotating body per unit time). In this embodiment, the maximum rotation speed of the impeller 1 is 50 rotations / s, the maximum frequency of the output signals from the magnetic sensors 4 and 5 is 100 Hz, and the frequency of the sampling pulse is 512 Hz. Thus, conventionally, when the duty ratio of the output signals of the two magnetic sensors is 30:70, it is necessary to set the frequency of the sampling pulse to a minimum of 2000 Hz. Without erroneous detection of the rotation direction of the car 1, the frequency of the sampling pulse can be set to 512 Hz, power consumption can be greatly reduced, and the battery life can be extended. In addition, since the rotational direction of the impeller 1 is determined in all rotational regions, erroneous detection of the rotational direction as in Patent Document 1 can be prevented.

このように、磁気センサ４，５からの出力信号におけるデューティ比が３０：７０と悪い場合においても、デューティ比５０：５０の場合とほぼ同じサンプリングパルスの周波数で対応することができ、消費電力をあまり増加することなく、広範囲の磁気センサを使用することができ、磁気センサの歩留まりを上げ、コスト低減を図ることができる。 Thus, even when the duty ratio in the output signals from the magnetic sensors 4 and 5 is as bad as 30:70, it is possible to cope with the sampling pulse frequency almost the same as in the case of the duty ratio 50:50, and the power consumption can be reduced. A wide range of magnetic sensors can be used without much increase, and the yield of the magnetic sensors can be increased and the cost can be reduced.

なお、前記実施例１においては、羽根車１の単位時間当りの回転数が、一定以上の高回転において、羽根車１の回転方向の判別が安定しないときに、切替部９は、演算部１０からの切替え信号により、第１と第２の状態を切替えたが、羽根車１の回転数に関係なく、羽根車１の回転方向の判別が安定しないときに、切替部９により第１と第２の状態を切替えるようにしてもよい。 In the first embodiment, when the rotational speed per unit time of the impeller 1 is high at a certain level or higher, the switching unit 9 is not operated when the rotational direction of the impeller 1 is not stable. The first and second states are switched by the switching signal from the first and second states. When the determination of the rotational direction of the impeller 1 is not stable regardless of the rotational speed of the impeller 1, the switching unit 9 causes the first and second states to be switched. The state 2 may be switched.

また、カウント信号の立上がりエッジと、立下がりエッジの双方で、羽根車１の正逆方向の判別を行ったが、カウント信号の立上がりエッジ又は立下がりエッジの何れか一方のみで羽根車１の回転方向の判別を行うようにしても良い。 Further, although the forward / reverse direction of the impeller 1 is determined at both the rising edge and the falling edge of the count signal, the rotation of the impeller 1 is detected only by either the rising edge or the falling edge of the count signal. The direction may be determined.

図５は実施例２を示す。
図５は、本実施例２の流量計の全体構成を示すブロック図である。 FIG. 5 shows a second embodiment.
FIG. 5 is a block diagram showing the overall configuration of the flow meter of the second embodiment.

磁気センサ４，５、駆動回路６、記憶部７，８、演算部１０は、前記実施例１と同様であり、本実施例２は、前記実施例１の切替部９の位置が異なる。 The magnetic sensors 4 and 5, the drive circuit 6, the storage units 7 and 8, and the calculation unit 10 are the same as in the first embodiment, and the position of the switching unit 9 in the first embodiment is different in the second embodiment.

本実施例２は、２つの磁気センサ４，５からの出力信号を、切替部１１に入力し、該切替部１１は、第１の磁気センサ４からの出力を第１記憶部７へ、第２の磁気センサ５からの出力を第２記憶部８へ入力する第１の状態と、第１の磁気センサ４からの出力を第２記憶部８へ、第２の磁気センサ５からの出力を第１記憶部７へ入力する第２の状態とに切替えることができるようになっている。この第１状態と第２状態の切替るタイミングは、前記実施例１と同様に行なわれる。 In the second embodiment, output signals from the two magnetic sensors 4 and 5 are input to the switching unit 11, and the switching unit 11 outputs the output from the first magnetic sensor 4 to the first storage unit 7. The first state in which the output from the second magnetic sensor 5 is input to the second storage unit 8, the output from the first magnetic sensor 4 to the second storage unit 8, and the output from the second magnetic sensor 5 to the second storage unit 8 It is possible to switch to the second state to be input to the first storage unit 7. The timing for switching between the first state and the second state is the same as in the first embodiment.

前記第１記憶部７はカウント信号と、第２記憶部８は回転方向信号として演算部１０へ出力する。 The first storage unit 7 outputs the count signal and the second storage unit 8 outputs the rotation direction signal to the calculation unit 10.

その他の構成は、前記実施例１と同様に構成されている。
本実施例２においても、前記実施例１と同様の効果を奏する。 Other configurations are the same as those in the first embodiment.
Also in the second embodiment, the same effects as in the first embodiment are obtained.

図６は実施例３を示す。
図６は、本実施例３の流量計の全体構成を示すブロック図である。 FIG. 6 shows a third embodiment.
FIG. 6 is a block diagram illustrating the overall configuration of the flow meter of the third embodiment.

磁気センサ４，５は、前記実施例１と同様である。駆動回路１６は、２つの磁気センサ４，５に、所定の間隔で間欠的に所定の短時間ずつ電源を供給して、磁気センサ４，５を駆動する。駆動回路１６は、所定の第１駆動間隔と、該第１駆動間隔よりも短い第２駆動間隔の２種類の間隔（周期）で電源を供給できるようになっている。駆動回路１６は、演算部１７からの選択信号により、第１駆動間隔か第２駆動間隔のいずれか一方を選択して、選択した駆動間隔で磁気センサ４，５に電源を供給するようになっている。 The magnetic sensors 4 and 5 are the same as in the first embodiment. The drive circuit 16 drives the magnetic sensors 4 and 5 by supplying power to the two magnetic sensors 4 and 5 intermittently at predetermined intervals for a predetermined short time. The drive circuit 16 can supply power at two types of intervals (cycles), which are a predetermined first drive interval and a second drive interval shorter than the first drive interval. The drive circuit 16 selects either the first drive interval or the second drive interval according to the selection signal from the calculation unit 17 and supplies power to the magnetic sensors 4 and 5 at the selected drive interval. ing.

本実施例３においては、駆動回路１６はサンプリングパルスを、第１駆動間隔における周波数：５１２Ｈｚ、第２駆動間隔における周波数：２０４８Ｈｚ、そのパルス幅は、その周期より大幅に短い時間（実施例では、２０μＳ）出力し、該サンプリングパルスが磁気センサ４，５の電源電圧として印加されて磁気センサ４，５を駆動する。 In the third embodiment, the drive circuit 16 uses the sampling pulse as the frequency at the first drive interval: 512 Hz, the frequency at the second drive interval: 2048 Hz, and the pulse width is a time significantly shorter than the cycle (in the embodiment, 20 μS), and the sampling pulse is applied as the power supply voltage of the magnetic sensors 4 and 5 to drive the magnetic sensors 4 and 5.

演算部１７は、所定間隔で所定の時間の間（本実施例においては、５秒間隔で０．５秒間）第２駆動間隔を選択する選択信号を、駆動回路１６へ出力している。すなわち、駆動回路１６は、通常は第１駆動間隔で、磁気センサ４，５に電源を供給し、所定間隔で所定の時間の間（本実施例においては、５秒間隔で０．５秒間）は、第１駆動間隔から第２駆動間隔へと切替えて、第２駆動間隔で、磁気センサ４，５に電源を供給するようになっている。 The computing unit 17 outputs a selection signal for selecting the second drive interval to the drive circuit 16 at a predetermined interval for a predetermined time (in this embodiment, 0.5 second at a 5-second interval). That is, the drive circuit 16 supplies power to the magnetic sensors 4 and 5 usually at a first drive interval, and for a predetermined time at a predetermined interval (in this embodiment, 0.5 seconds at an interval of 5 seconds). Is switched from the first drive interval to the second drive interval, and power is supplied to the magnetic sensors 4 and 5 at the second drive interval.

前記第１の磁気センサ４からの出力が、第１記憶部１８に入力され、第２の磁気センサ５からの出力が、第２記憶部１９に入力されている。２つの記憶部１８，１９には、駆動回路１６から磁気センサ４，５への電源供給と同じタイミングで記憶タイミング信号が入力され、記憶部１８，１９は、記憶タイミング信号の入力の際の磁気センサ４，５の出力の状態（ＨｉｇｈレベルかＬｏｗレベル）を記憶する。 An output from the first magnetic sensor 4 is input to the first storage unit 18, and an output from the second magnetic sensor 5 is input to the second storage unit 19. A storage timing signal is input to the two storage units 18 and 19 at the same timing as the power supply from the drive circuit 16 to the magnetic sensors 4 and 5, and the storage units 18 and 19 are magnetic when the storage timing signal is input. The output state (High level or Low level) of the sensors 4 and 5 is stored.

第１記憶部１８は、記憶した状態をカウント信号として、第２記憶部１９は、記憶した状態を回転方向信号して演算部１７へ出力する。前記演算部１７は、前記実施例１の演算部１０と同様に、羽根車１の回転方向を判別して、羽根車１の１／４回転に相当する値を記憶していた直前の積算値に加算又は減算し、新しい積算値を記憶するとともに、図示しない表示部に新しい積算値から流量等を演算し更新表示する。 The first storage unit 18 uses the stored state as a count signal, and the second storage unit 19 outputs the stored state to the calculation unit 17 as a rotation direction signal. Similar to the calculation unit 10 of the first embodiment, the calculation unit 17 discriminates the rotation direction of the impeller 1 and stores the integrated value immediately before storing a value corresponding to ¼ rotation of the impeller 1. Is added or subtracted to store the new integrated value, and the flow rate and the like are calculated from the new integrated value on a display unit (not shown) and updated.

第１記憶部１８は、記憶した状態をカウント信号として、回転数判別部２０へ出力する。該回転数判別部２０は、カウント信号の１周期の時間を測定し、その時間より羽根車１の単位時間当りの回転数を演算し、その回転数が、所定値（本実施例においては１０回転／ｓ）より大きいか否かを判別するようになっている。 The first storage unit 18 outputs the stored state to the rotation speed determination unit 20 as a count signal. The rotational speed discriminating unit 20 measures the time of one cycle of the count signal, calculates the rotational speed per unit time of the impeller 1 from the time, and the rotational speed is a predetermined value (10 in this embodiment). It is determined whether or not the rotation is greater than (rotation / s).

前記回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別したときは、回転数信号を演算部１７へ出力する。演算部１７は、回転数信号が入力されると、第２駆動間隔のみで羽根車１の回転方向を判別し、第１駆動間隔では羽根車１の回転方向の判別を行わないようし、第１駆動間隔における羽根車１の回転方向は、直前に判別した回転方向を採用して、加算又は減算するようになっている。すなわち、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別したときは、第２駆動間隔のみで羽根車１の回転方向の判別を行い、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値以下と判別したときは、第１駆動間隔と第２駆動間隔の両方で羽根車１の回転方向の判別を行うようになっている。 When the rotational speed determination unit 20 determines that the rotational speed per unit time of the impeller 1 is greater than a predetermined value, the rotational speed signal is output to the calculation unit 17. When the rotation number signal is input, the calculation unit 17 determines the rotation direction of the impeller 1 only at the second drive interval, and does not determine the rotation direction of the impeller 1 at the first drive interval. As the rotation direction of the impeller 1 in one drive interval, the rotation direction determined immediately before is adopted and added or subtracted. That is, when the rotational speed determination unit 20 determines that the rotational speed per unit time of the impeller 1 is larger than a predetermined value, the rotational speed of the impeller 1 is determined only by the second drive interval, and the rotational speed determination is performed. When the rotational speed per unit time of the impeller 1 is determined to be equal to or less than a predetermined value, the unit 20 determines the rotational direction of the impeller 1 at both the first drive interval and the second drive interval. Yes.

磁気センサ４，５のデューティ比が３０：７０の場合で、羽根車１の全ての回転域において、羽根車１の回転方向を精度良く判別するには、羽根車１の最大回転数を５０回転／ｓとした場合には、前述のように、サンプリングパルスを２０００Ｈｚ以上にする必要がある。しかし、本実施例においては、サンプリングパルスを、４．５秒間：５１２Ｈｚ、０．５秒間：２０４８Ｈｚとなるように、５１２Ｈｚと２０４８Ｈｚを交互に切替えることにより、消費電力を、常に、サンプリングパルスの周波数を２０００Ｈｚにした場合の約１／３とすることができる。 In the case where the duty ratio of the magnetic sensors 4 and 5 is 30:70, the rotational speed of the impeller 1 can be accurately determined in the entire rotational range of the impeller 1 with the maximum rotational speed of the impeller 1 being 50 rotations. In the case of / s, it is necessary to set the sampling pulse to 2000 Hz or more as described above. However, in the present embodiment, the sampling pulse is alternately switched between 512 Hz and 2048 Hz so that the sampling pulse is 4.5 seconds: 512 Hz and 0.5 second: 2048 Hz, so that the power consumption is always equal to the frequency of the sampling pulse. Can be reduced to about of 2000 Hz.

また、羽根車１の高回転域では、羽根車１の回転方向が変化することは殆どないため、前記特許文献１では、高回転域では羽根車１の回転方向の判別を行わないようにしている。しかし、前述のように、羽根車１の回転方向の判別を行った直後に、羽根車１が直前の判別方向とは逆方向に回転するとともに、一気に回転数が、所定値以上となってしまった場合には、羽根車１の回転方向の誤検知をしてしまい、その回転方向の誤検知は、回転数が下がるまで訂正することが出来ない虞がある。しかし、本実施例では、高回転域において、判別精度の低い第１駆動間隔では羽根車１の回転方向を判別せず、時々、判別精度の高い第２駆動間隔で、羽根車１の回転方向を判別するようにしたことにより、前記特許文献１のような問題点を解消することができる。 In addition, since the rotation direction of the impeller 1 hardly changes in the high rotation range of the impeller 1, in the above-mentioned Patent Document 1, the rotation direction of the impeller 1 is not determined in the high rotation range. Yes. However, as described above, immediately after the determination of the rotation direction of the impeller 1, the impeller 1 rotates in the direction opposite to the immediately previous determination direction, and the number of rotations suddenly becomes a predetermined value or more. In such a case, the rotational direction of the impeller 1 is erroneously detected, and the erroneous detection of the rotational direction may not be corrected until the rotational speed is decreased. However, in this embodiment, in the high rotation range, the rotation direction of the impeller 1 is not determined at the first drive interval with low determination accuracy, and sometimes the rotation direction of the impeller 1 at the second drive interval with high determination accuracy. Therefore, the problem as in Patent Document 1 can be solved.

なお、前記実施例３においては、第１記憶部１８からの出力を、カウント信号とし、第２記憶部１９からの出力を回転方向信号としたが、第２記憶部１９からの出力を、カウント信号とし、第１記憶部１８からの出力を回転方向信号としてもよい。 In the third embodiment, the output from the first storage unit 18 is a count signal and the output from the second storage unit 19 is a rotation direction signal. However, the output from the second storage unit 19 is counted. It is good also as a signal and making the output from the 1st memory | storage part 18 into a rotation direction signal.

また、第１駆動間隔と第２駆動間隔における、夫々のサンプリングパルスの周波数を５１２Ｈｚ、２０４８Ｈｚ以外にも、羽根車１の回転方向の判別が精度良く行えれば任意の周波数に設定することができる。 In addition to the sampling pulse frequencies in the first driving interval and the second driving interval other than 512 Hz and 2048 Hz, any frequency can be set as long as the rotational direction of the impeller 1 can be accurately determined. .

前記実施例３においては、羽根車１の全ての回転域において、所定間隔で所定の時間の間、第１駆動間隔から第２駆動間隔へと切替えて、磁気センサ４，５に電源供給を行うようにしたが、回転数判別部２０で羽根車１の単位時間当りの回転数が所定値以下と判別したときは、第２駆動間隔へ切替えることなく、常に第１駆動間隔で磁気センサ４，５に電源供給を行い、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別したときに、所定間隔で所定の時間の間は、第１駆動間隔から第２駆動間隔へと切替えて磁気センサ４，５に電源供給を行うようにしてもよい。 In the third embodiment, power is supplied to the magnetic sensors 4 and 5 by switching from the first drive interval to the second drive interval at predetermined intervals for a predetermined time in all rotation regions of the impeller 1. However, when the rotational speed discriminating unit 20 determines that the rotational speed of the impeller 1 per unit time is equal to or less than a predetermined value, the magnetic sensor 4 is always switched at the first driving interval without switching to the second driving interval. 5, and when the rotational speed determination unit 20 determines that the rotational speed per unit time of the impeller 1 is greater than a predetermined value, the first drive interval starts at a predetermined interval. The magnetic sensors 4 and 5 may be supplied with power by switching to the second drive interval.

回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別した場合は、前記実施例３と同様に、第２駆動間隔のみで羽根車１の回転方向を判別し、第１駆動間隔では羽根車１の回転方向の判別を行わないようし、第１駆動間隔における羽根車１の回転方向は、直前に判別した回転方向を採用するようになっている。なお、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値以下と判別した場合は、第１駆動間隔で羽根車１の回転方向の判別を行う。 When the rotational speed discriminating unit 20 determines that the rotational speed per unit time of the impeller 1 is larger than a predetermined value, the rotational direction of the impeller 1 is discriminated only by the second drive interval as in the third embodiment. The rotation direction of the impeller 1 is not determined at the first drive interval, and the rotation direction determined immediately before is employed as the rotation direction of the impeller 1 at the first drive interval. In addition, when the rotation speed discrimination | determination part 20 discriminate | determines that the rotation speed per unit time of the impeller 1 is below a predetermined value, it discriminate | determines the rotation direction of the impeller 1 at a 1st drive space | interval.

その他の構成は、前記実施例３と同様に構成されている。
本実施例４においても、前記実施例３と同様の効果を奏する。 Other configurations are the same as those in the third embodiment.
Also in the fourth embodiment, the same effects as in the third embodiment are obtained.

更に、本実施例４は、羽根車１の低回転域においては、第１駆動間隔のみとしたことで、前記実施例３よりもより消費電力を抑えることができる。 Further, in the fourth embodiment, the power consumption can be suppressed more than that in the third embodiment by setting only the first drive interval in the low rotation range of the impeller 1.

前記実施例４においては、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値以下と判別したときは、第２駆動間隔へ切替えることなく、常に第１駆動間隔で磁気センサ４，５に電源供給を行い、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別したときに、所定間隔で所定の時間の間は、第１駆動間隔から第２駆動間隔へと切替えるようにしたが、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別したときに、第２駆動間隔に切替えて所定の時間（本実施例においては０．５ｓ）第２駆動間隔で磁気センサ４，５に電源供給を行い、その後、回転数判別部２０が羽根車１の単位時間当りの回転数が所定値以下と判別するまでの間は、第２駆動間隔に切替えることなく、第１駆動間隔で磁気センサ４，５に電源を供給行うようにしてもよい。 In the fourth embodiment, when the rotational speed determination unit 20 determines that the rotational speed of the impeller 1 per unit time is equal to or less than a predetermined value, the magnetic force is always generated at the first driving interval without switching to the second driving interval. When power is supplied to the sensors 4 and 5 and the rotational speed discriminating unit 20 determines that the rotational speed per unit time of the impeller 1 is larger than a predetermined value, the first time is maintained at a predetermined interval for a predetermined time. Although the drive interval is switched to the second drive interval, when the rotational speed determination unit 20 determines that the rotational speed per unit time of the impeller 1 is larger than a predetermined value, the rotational interval is switched to the second drive interval. Power is supplied to the magnetic sensors 4 and 5 at a second drive interval for a predetermined time (0.5 s in this embodiment), and then the rotational speed discriminating unit 20 determines that the rotational speed per unit time of the impeller 1 is a predetermined value. It is possible to switch to the second drive interval until it is determined that Without the power to the magnetic sensors 4 and 5 may be carried out provided in the first driving distance.

その他の構成は、前記実施例４と同様に構成されている。
本実施例５においても、前記実施例４と同様の効果を奏する。 Other configurations are the same as those in the fourth embodiment.
Also in the fifth embodiment, the same effects as in the fourth embodiment are obtained.

更に、本実施例５は、第２駆動間隔で磁気センサ４，５に電源を供給行う時間を前記実施例４よりも更に短くすることで、前記実施例４よりもより消費電力を抑えることができる。 Further, in the fifth embodiment, the time for supplying power to the magnetic sensors 4 and 5 at the second drive interval is further shortened than that in the fourth embodiment, so that the power consumption can be suppressed more than in the fourth embodiment. it can.

羽根車１が、ある回転方向で高速回転をしている場合に、第１駆動間隔の間に、低速回転をへることなく反対方向へ高速回転に転じる可能性は極めて低いために、本実施例５でも羽根車１の回転方向を正確に判別することができる。 When the impeller 1 rotates at a high speed in a certain rotation direction, the possibility of turning to a high speed rotation in the opposite direction without going through a low speed rotation is extremely low during the first drive interval. Even in Example 5, the rotational direction of the impeller 1 can be accurately determined.

前記実施例５においては、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別したときに、所定の時間（本実施例においては０．５ｓ）第２駆動間隔で磁気センサ４，５に電源供給を行い、その後、羽根車１の単位時間当りの回転数が所定値以下と判別するまでの間は、第２駆動間隔に切替えることなく、第１駆動間隔で磁気センサ４，５に電源を供給行うようにしたが、回転数判別部２０が、羽根車１の単位時間当りの回転数が所定値より大きいと判別したときに、第２駆動間隔に切替えて磁気センサ４，５に電源供給を行い、第２駆動間隔に切替えた後の羽根車１の回転方向の判別で、回転方向の判別結果が、所定回数（本実施例においては２回）同じとなるまで第２駆動間隔で磁気センサ４，５に電源供給を行い、その後、回転数判別部２０が羽根車１の単位時間当りの回転数が所定値以下と判別するまでの間は、第２駆動間隔に切替えることなく、第１駆動間隔で磁気センサ４，５に電源を供給行うようにしてもよい。 In the fifth embodiment, when the rotational speed determination unit 20 determines that the rotational speed per unit time of the impeller 1 is larger than a predetermined value, the predetermined time (0.5 s in this embodiment) is the second time. The first drive is performed without switching to the second drive interval until power is supplied to the magnetic sensors 4 and 5 at the drive interval and then the rotational speed per unit time of the impeller 1 is determined to be equal to or less than a predetermined value. The power is supplied to the magnetic sensors 4 and 5 at intervals, but when the rotation speed determination unit 20 determines that the rotation speed per unit time of the impeller 1 is greater than a predetermined value, the second drive interval is set. By switching the power supply to the magnetic sensors 4 and 5 and determining the rotation direction of the impeller 1 after switching to the second drive interval, the determination result of the rotation direction is a predetermined number of times (in this embodiment, twice). Provide power to magnetic sensors 4 and 5 at the second drive interval until the same. After that, until the rotational speed discriminating unit 20 determines that the rotational speed per unit time of the impeller 1 is equal to or less than a predetermined value, the magnetic sensor 4 is switched at the first driving interval without switching to the second driving interval. , 5 may be supplied with power.

その他の構成は、前記実施例５と同様に構成されている。
本実施例６においても、前記実施例５と同様の効果を奏する。 Other configurations are the same as those in the fifth embodiment.
Also in the sixth embodiment, the same effects as in the fifth embodiment are obtained.

更に、本実施例６は、第２駆動間隔で磁気センサ４，５に電源を供給行う時間を前記実施例５よりも更に短くすることで、前記実施例５よりもより消費電力を抑えることができる。 Further, in the sixth embodiment, the time for supplying power to the magnetic sensors 4 and 5 at the second drive interval is further shortened than that in the fifth embodiment, so that the power consumption can be suppressed more than in the fifth embodiment. it can.

前記実施例３〜６においては、羽根車１の回転方向の判別を行わない際に、駆動回路１６から、その信号を回転方向信号として用いる磁気センサ５（４）も電源を供給していたが、羽根車１の回転方向の判別を行わない際には、駆動回路１６から、その信号を回転方向信号として用いる磁気センサ５（４）で電源を供給しないようにしてもよい。 In Examples 3 to 6, when the rotational direction of the impeller 1 is not determined, the magnetic sensor 5 (4) using the signal as the rotational direction signal is also supplied with power from the drive circuit 16. When the rotational direction of the impeller 1 is not determined, the drive circuit 16 may not supply power to the magnetic sensor 5 (4) using the signal as the rotational direction signal.

その他の構成は、前記実施例３〜６と同様に構成されている。
本実施例７においても、前記実施例３〜６と同様の効果を奏する。 Other configurations are the same as those in the third to sixth embodiments.
In Example 7, the same effects as those in Examples 3 to 6 are obtained.

１羽根車（回転体）
２磁石
４第１の磁気センサ
５第２の磁気センサ
６，１６駆動回路
７，１８第１記憶部
８，１９第２記憶部
９，１１切替部
１０，１７演算部 1 impeller (rotary body)
2 magnet 4 first magnetic sensor 5 second magnetic sensor 6, 16 drive circuit 7, 18 first storage unit 8, 19 second storage unit 9, 11 switching unit 10, 17 calculation unit

Claims

The first magnetic sensor and the second magnetism are arranged so that the rotation of the magnet that rotates together with the rotating body that rotates according to the flow of the fluid is detected and output as a square wave signal, and the outputs thereof have a phase difference from each other. A sensor,
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A first storage unit that stores an output of the first magnetic sensor when power is supplied from the drive circuit to the magnetic sensor, and an output of the second magnetic sensor when power is supplied from the drive circuit to the magnetic sensor. A second storage unit for storing;
The first state where the output from the first storage unit is the count signal, the output from the second storage unit is the rotation direction signal, the output from the second storage unit is the count signal, and the output from the first storage unit is rotated A switching unit for switching between the second state as the direction signal;
An arithmetic unit that performs an addition operation or a subtraction operation depending on the state of the rotation direction signal at the rising edge of the count signal or / and the falling edge of the count signal;
A flowmeter, wherein the first state and the second state are switched by a switching signal from the arithmetic unit.

The first magnetic sensor and the second magnetism are arranged so that the rotation of the magnet that rotates together with the rotating body that rotates according to the flow of the fluid is detected and output as a square wave signal, and the outputs thereof have a phase difference from each other. A sensor,
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A first storage for storing one output of the two magnetic sensors at the time of power supply from the drive circuit to the magnetic sensor; a second storage for storing the other output;
The first state in which the output from the first magnetic sensor is input to the first storage unit and the output from the second magnetic sensor is input to the second storage unit, and the output from the first magnetic sensor is the second A switching unit that switches between a second state of inputting to the storage unit and inputting an output from the second magnetic sensor to the first storage unit;
One of the output from the first storage unit and the output from the second storage unit is used as a count signal, and the other is used as a rotation direction signal. At the rising edge of the count signal or / and at the falling edge of the count signal A calculation unit that performs an addition operation or a subtraction operation depending on the state of the rotation direction signal;
A flowmeter, wherein the first state and the second state are switched by a switching signal from the arithmetic unit.

According to the state of the rotation direction signal at the rising edge of the count signal or / and the falling edge of the count signal, the rotation direction of the rotating body is determined,
When the rotational speed of the rotating body is greater than or equal to a predetermined value, when the rotation direction of the rotating body is determined, when the forward rotation and the reverse rotation are mixed, the first state and the second state are switched. The flow meter according to claim 1 or 2, wherein

According to the state of the rotation direction signal at the rising edge of the count signal or / and the falling edge of the count signal, the rotation direction of the rotating body is determined,
When the rotational speed of the rotating body is equal to or greater than a predetermined value, the first state and the second state are switched when the rotational direction of the rotating body is different from the previous determination. The flow meter according to claim 1 or 2 .

A first magnetic sensor and a second magnetic sensor arranged to detect rotation of a magnet that rotates together with a rotating body that rotates in accordance with a flow of fluid, and whose output signals have a phase difference from each other;
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval, and supplies power to the magnetic sensor at a second drive interval shorter than the first drive interval for a predetermined time at a predetermined interval;
When the number of rotations of the rotating body per unit time is larger than a predetermined value, the rotation direction of the rotating body is determined only at the second driving interval, and at the first driving interval, the rotating direction of the rotating body is determined. The flowmeter is characterized in that the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before the determination.

A first magnetic sensor and a second magnetic sensor arranged to detect rotation of a magnet that rotates together with a rotating body that rotates in accordance with a flow of fluid, and whose output signals have a phase difference from each other;
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval, and when the number of rotations of the rotating body per unit time is larger than a predetermined value, Supplying power to the magnetic sensor at a second driving interval shorter than the first driving interval;
When the number of rotations of the rotating body per unit time is larger than a predetermined value, the rotation direction of the rotating body is determined only at the second driving interval, and at the first driving interval, the rotating direction of the rotating body is determined. The flowmeter is characterized in that the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before the determination.

A first magnetic sensor and a second magnetic sensor arranged to detect rotation of a magnet that rotates together with a rotating body that rotates in accordance with a flow of fluid, and whose output signals have a phase difference from each other;
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval;
When the number of rotations per unit time of the rotating body is greater than a predetermined value, in the determination result of the rotating direction of the rotating body, until the determined rotating direction is the same as a predetermined number of times. The power source is supplied to the magnetic sensor at a second driving interval shorter than the first driving interval, and thereafter, the rotational direction of the rotating body is determined until the rotational speed per unit time of the rotating body becomes a predetermined value or less. The flowmeter is characterized in that the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before.

A first magnetic sensor and a second magnetic sensor arranged to detect rotation of a magnet that rotates together with a rotating body that rotates in accordance with a flow of fluid, and whose output signals have a phase difference from each other;
A drive circuit that drives the two magnetic sensors by supplying power intermittently for a predetermined time; and
A calculation unit that performs an addition operation or a subtraction operation by determining the rotation direction of the rotating body from the output signal from the first magnetic sensor and the output signal from the second magnetic sensor;
The drive circuit supplies power to the magnetic sensor at a first drive interval;
When the number of rotations of the rotating body per unit time is greater than a predetermined value, power is supplied to the magnetic sensor at a second driving interval shorter than the first driving interval for a predetermined time, and thereafter the rotation is performed. Until the number of rotations per unit time of the body becomes a predetermined value or less, the rotation direction of the rotating body is not determined, and the addition operation or the subtraction operation is performed based on the rotation direction determined immediately before. Flow meter to do.

The output from one magnetic sensor is used as a count signal, and the output from the other magnetic sensor is used as a rotation direction signal to determine the rotation direction of the rotating body,
The flowmeter according to any one of claims 5 to 8, wherein when the rotation direction of the rotating body is not determined, power is not supplied to the magnetic sensor used as the rotation direction signal.