JP3055360B2 - Flowmeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic flow meter for detecting a flow rate and a flow direction using two sensors.

[0002]

2. Description of the Related Art In a flow meter such as a water meter or a gas meter, the rotation of a rotating body such as an impeller provided with a magnet is detected by a magneto-electric conversion element and converted into an electric signal. An electronic type that measures the amount of gas or gas used is used.

In such an electronic type flow meter, two sets of sensor units for detecting rotation are provided in order to detect whether the flow direction is forward flow or reverse flow, and the output signal of one sensor unit is used for detecting the flow direction. The sensor of one sensor unit is displaced in the rotational direction with respect to the sensor of the other sensor unit so as to obtain a signal advanced by 90 degrees in electrical angle from the output signal of
A forward / reverse determination unit that compares the phases of the output signals of both sensor units and determines whether the flow is forward or reverse depending on which sensor unit has the advanced output signal phase.

[0004] In such a flowmeter, analog signals detected by a magnetoelectric conversion element or the like are compared by a comparator or the like using a certain threshold value, and a binary value is used as a signal of a sensor unit. .

[0005]

However, according to the above conventional method, when the output of the magneto-electric conversion element becomes close to the threshold,
When a flow rate occurs and the rotating body is rotating, the output of the sensor section does not greatly differ from the ideal output even if a slight change in duty occurs, but no flow rate occurs and the rotating body is rotated. If the rotation stops at a position where the output of the magneto-electric conversion element is near the threshold, the output signal of the sensor unit is not stable because the output of the comparator is not stable. A signal may be output as if a flow rate is occurring. Stochastically, it is rare for the rotating body to stop at such a position, and even if it stops, there is no effect to some extent by sampling the output signal of the sensor unit at a fixed cycle or by giving the comparator hysteresis. I was able to do it. On the other hand, instead of such noise, a change in the surrounding environment, such as the use situation of the neighbor, causes a slight change in pressure, causing the rotating body to vibrate, and as if the flow rate was generated. Output such a signal,
There was a problem that the flow rate measurement was adversely affected.
As a countermeasure in such a case, it is conceivable to increase the hysteresis of the comparator.However, by increasing the hysteresis, the sensitivity of the sensor unit is reduced, and the detection becomes impossible unless the magnetic flux density change is sufficient. Due to the possibility, it was not easy to take countermeasures.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flow meter which can take measures against noise and the like to correctly detect a flow rate without changing the configuration of a sensor section in order to solve the above-mentioned problems.

[0007]

In order to solve the above-mentioned problems, a flow meter according to the present invention comprises first and second sensor sections having different output signal phases, and a change in the first and second sensor sections. A first and a second change detecting unit for detecting a flow rate, a calculating unit for calculating a flow rate in accordance with a change in an output of the first sensor unit detected by the first change detecting unit, and the second change An operation permitting unit that permits the operation of the operation unit when a change in the output of the second sensor unit is detected by the detection unit.

Further, a forward / reverse determining unit for determining a flow direction from output signals of the first and second sensor units, and a forward / reverse determining unit for detecting that the flow direction determined by the forward / reverse determining unit has changed. An inverse change detection unit.

[0009]

In the above configuration, the first and second sensor units convert the flow rate into an electric signal and transmit the electric signal to the first and second change detecting units. The first and second change detection units detect a change in the signal from the first and second sensor units and transmit the detected change to the calculation unit and the calculation permission unit, respectively. The calculation permission unit permits the calculation of the calculation unit when a change in the output signal of the first sensor unit is transmitted from the second change detection unit, and the calculation unit is permitted to perform the calculation by the calculation permission unit. Then, the first
The flow rate is calculated according to the change in the output of the first sensor unit transmitted from the change detection unit. On the other hand, the calculation permission means inhibits the calculation of the calculation means again when the calculation of the flow rate by the calculation means ends, and until the change of the output signal of the second sensor unit is detected by the second change detection means. It works so as not to perform the flow rate calculation and does not accept the noise of the output signal of the first sensor unit.

The forward / reverse determining unit determines the direction of the flow from the output signals of the first and second sensor units and transmits the result to a forward / reverse change detecting unit. Is detected and transmitted to the calculation permission unit. The calculation permitting unit functions to permit the calculation of the calculation unit when a change in the direction of the flow is detected by the forward / reverse change detection unit, enables a flow rate calculation when the direction of the flow changes, and Reduce the measurement error when inverted.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a flow meter according to the present invention. Reference numeral 1 denotes a first sensor unit, 2 denotes a second sensor unit, 3 denotes a first change detection unit, and 4 denotes a second change detection unit. Reference numeral 5 denotes an operation unit, reference numeral 6 denotes an operation permission unit, and reference numeral 7 denotes a rotating body. FIG. 2 is a time chart for explaining the operation of the flow meter.

The first and second sensor units 1 and 2 detect a magnetic field generated from a rotating body 7 having a built-in magnet which rotates according to the flow rate and the direction of the flow, and correspond to flow rates having different phases. It is provided so as to output a rectangular wave (MR1, MR2) having a frequency. In this embodiment, the signal MR1 of the first sensor unit 1 advances by about 90 electrical degrees from the signal MR2 of the second sensor unit 2 when the flow direction is the forward direction (forward flow), and in the reverse direction (reverse flow). About 90 degrees behind.

The first and second change detecting sections 3 and 4 output signals MR1 and MR of the first and second sensor sections 1 and 2, respectively.
2 is detected and signals (P1, P2) are output. When detecting the rising edge of the signal P1 output from the first change detection unit 3, the calculation unit 5 performs a calculation for converting the pulse into a flow rate. ) Is output. On the other hand, at the rising edge of the output signal P2 of the second change detection unit 4, the calculation permission unit 6 sets the signal (EN) for permitting the calculation of the flow rate of the calculation unit 5 with logic H to logic H (permission). The logic L (prohibited) is set at the fall of the output signal BUSY of the arithmetic unit 5.

Now, the output signal MR1 of the first sensor unit 1 will be described.
Is unstable at the rising edge and has a waveform as shown in FIG. 2, the first change detection section 3 outputs a pulse as a signal P1 at timings a, b, and c in synchronization with the rising edge of MR1. The calculation unit 5 calculates the flow rate by the rise of the signal P1 at the timing a because the signal EN is logic H. When the flow rate calculation ends and the signal BUSY falls (d), the calculation permission unit 6 sets the signal EN to logic L,
Until the rising edge (e) of the MR2 is detected and the signal EN becomes the logic H again, the flow rate calculation by the rising edge of the signal P1 at the timings b and c is prohibited, and two of the three rising edges of the MR1 are noise. The signal is ignored, and errors in flow measurement due to such noise are eliminated.

A second embodiment will be described with reference to the drawings. FIG. 3 is a block diagram for explaining the configuration of the second embodiment, wherein 1 to 7 have the same names and operations as in the first embodiment. Numeral 8 denotes a forward / reverse determination unit which determines the direction of flow if the logic of the output signal MR2 of the second sensor unit 2 after the rise and fall of the output signal MR1 of the first sensor unit is the same as that of MR1; If they are different, it is determined to be in the reverse direction and output as the forward / reverse signal FR. Reference numeral 9 denotes a forward / reverse change detecting unit which detects a rise or a fall of the forward / reverse signal FR and outputs a pulse signal (P3). FIG.
9 is a timing chart for explaining a second embodiment of the present invention.

When the rotation of the rotating body 7 changes from the reverse direction to the forward direction at the timing f, and the output signals MR1 and MR2 of the first and second sensor units have waveforms as shown in FIG. The change detection unit 3 outputs a pulse signal P1 at timings g, i, and k in synchronization with the rise of MR1.
The operation at timings g to i is the same as in the first embodiment. When the signal P1 rises at the timing i, the arithmetic unit 5
Calculates the flow rate because the signal EN is logic H. When the flow calculation ends and the signal BUSY falls (o), the calculation permission unit 6 sets the signal EN to logic L and prohibits the calculation by the calculation unit 5. On the other hand, when the direction of the flow changes at the timing f, the output signal FR of the forward / reverse determining unit 8 changes from the reverse rotation to the normal rotation at the falling edge (j) of the MR1. The forward / reverse change detecting section 9 detects this change and outputs a pulse signal as a signal P3. The rising edge of the signal P3 allows the operation permitting section 6 to permit the operation of the operation section 5;
The flow rate calculation at the rise of 1 is performed, and even when the direction of the flow changes, a more accurate flow rate measurement can be performed without missing a signal.

In the embodiments of the present invention, specific components have been described. However, if implemented by software using a program, in addition to the above-described effects, there is an effect that the configuration and realization can be made inexpensively and easily. .

[0018]

As is clear from the above description, the flowmeter of the present invention works so as to permit the calculation of the output of the first sensor unit by the calculation unit by allowing the output of the second sensor unit to change. Even if the noise component is mixed in one signal and it is unstable, the flow rate calculation is controlled by using the other signal in which the noise is not mixed. is there.

In addition, since the forward / reverse determination is performed and the flow rate calculation is permitted when the flow direction changes, the flow rate signal is not ignored as noise when the flow direction changes. There is the effect that more accurate flow measurement can be performed while obtaining.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the first embodiment of the present invention;

FIG. 3 is a block diagram for explaining the operation of the second embodiment of the present invention;

FIG. 4 is a time chart for explaining the operation of the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st sensor part 2 2nd sensor part 3 1st change detection part 4 2nd change detection part 5 calculation part 6 calculation permission part 7 rotating body 8 forward / reverse determination part 9 forward / reverse change detection part

────────────────────────────────────────────────── (5) References JP-A-61-288122 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 15/075 G01P 13/00

Claims (2)

(57) [Claims] A first sensor unit for detecting a flow rate and a direction of a flow, wherein the first and second sensor units have different phases of output signals;
And a first and a second change detecting section for detecting a change in an output signal of the second sensor section, and a flow rate according to a change in an output of the first sensor section detected by the first change detecting section. An operation unit that performs an operation, and an operation permission unit that permits the operation of the operation unit when a change in the output of the second sensor unit is detected by the second change detection unit. The flowmeter according to claim 1, wherein when the operation of the change of the output of the first sensor unit is completed by the operation unit, the operation of the operation unit is prohibited. 2. A forward / reverse determining unit for determining a flow direction from output signals of a first and a second sensor unit, and a forward / reverse change detection for detecting a change in a flow direction determined by the forward / reverse determining unit. 2. The flow meter according to claim 1, further comprising: a calculation unit configured to permit the calculation by the calculation unit when a change in the direction of the flow is detected by the forward / reverse change detection unit.