JP3222017B2 - Electronic water meter - 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 water meter.

[0002]

2. Description of the Related Art An electronic water meter using a magnetoresistive element as a rotation detector for detecting the rotation direction of an impeller is rotated by flowing water flowing inside as shown in, for example, Japanese Patent Application Laid-Open No. 54-141166. In order to detect the rotation direction (forward rotation and reverse rotation) of the impeller, two pulse outputs having different phases are obtained.

[0003] Such an electronic water meter will be described with reference to FIG. In the figure, a pair of detectors 1A and 1B using a magnetoresistive element are radially arranged on a substrate so as to form an included angle of 45 ° with respect to an axis, and rotation detection circuits 9A and 9B are incorporated in this substrate. Have been. In the rotation detecting circuits 9A and 9B, power is constantly supplied to each of the detectors 1A and 1B and the comparators 2A and 2B.
The pulses output from A and 1B are detected.

That is, when the shaft of the impeller is rotating forward,
An impeller rotating clockwise with this axis is first detected by a detector 1B incorporated in a rotation detection circuit 9B, and the resistivity of a magnetoresistive element inside the detector 1B changes.
The voltage between the ground potentials due to this change is determined by the comparator 2B.
Is input to the positive side of.

On the negative side of the comparator 2B, the cathode side of the Zener diode 6B is connected between a ground conductor (not shown), and when a signal passing through the impeller is input from the detector 1B, as shown in FIG. The square pulse pulse Pa to C
Output to PU3.

When the shaft of the impeller further rotates clockwise,
The voltage between the ground potential due to the change in the resistivity of the magnetoresistive element inside the detector 1A, which is arranged at 45 ° clockwise with respect to the detector 1B, is applied to the comparator 2A incorporated in the rotation detection circuit 9A. Input to the positive side. Then, at the timing of the center of the pulse Pa of the comparator 2B, the comparator 2A outputs the pulse
To enter. Hereinafter, this is repeated for each rotation of the shaft 8. Note that, similarly to the comparator 2B, the cathode side of the Zener diode 6A is connected to the negative side of the comparator 2A.

On the other hand, the other side of the detectors 1A and 1B, one side of which is connected to the ground bus, and each of the comparators 2A, 2B and C
The power terminals of the PU 3 are connected to the power source 5 of the battery.

FIG. 10B shows the output from each of the comparators 2A and 2B when the axis of the impeller is reversed in the counterclockwise direction due to, for example, a rupture of the water pipe on the upstream side of the electronic water meter. FIG. 7 is a diagram showing timings of the applied pulses Pa and Pb.
Contrary to FIG. 10A, the pulse Pb is applied at the center of the pulse Pa.
Is standing up.

Therefore, the CPU 3 determines the forward / reverse rotation of the impeller based on the timing and manner of the pulses Pa and Pb input from the comparators 2A and 2B using the matrix shown in Table 1.

[0010]

[Table 1]

That is, when the pulse Pa is at or before the rising and the pulse Pa is “high”, or when the pulse Pa is at or before the rising and the pulse Pb is “low”, the normal rotation is determined. . In addition, when the pulse Pa is rising or before or after the rising and the pulse Pb is “low”, or when the pulse Pa is rising or before or after the rising and the pulse Pb is “high”, it is determined that the rotation is reverse.

On the load side of the power supply 5, switches 4A and 4B are provided, for example, as shown in JP-A-6-66615, in order to reduce the consumption of the battery serving as the power supply 5.
Detectors 1A and 1B and comparators 2A and 2 only when necessary
B and the CPU 3 are energized.

[0013]

Such an electronic water meter, as disclosed in Japanese Patent Application Laid-Open No. 6-66615, has a problem that when sampling is performed at a period following a change of two output pulses, a forward rotation is performed. -The status of the sampling result at the time of reverse rotation changes as shown in Table 2. However, when the phases of the two pulses are extremely deviated due to errors in the arrangement of the rotation detector, sensitivity, magnet magnetization, and the like, for example, as shown in Table 3, sampling follows the change in the status of the two output pulses. In other words, there is a possibility that the direction of rotation of the rotating body is erroneously determined.

For this reason, it is necessary to always perform sampling at very short intervals in consideration of the phase shift between the two output pulses. However, if the difference between the two output pulses is not large, an extra current is consumed by the rotation detector, and the current consumption cannot be reduced sufficiently efficiently.

[0015]

[Table 2]

[0016]

[Table 3] An object of the present invention is to provide a high-precision electronic water meter capable of efficiently reducing current consumption.

[0017]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a plurality of rotation detecting means for detecting rotation of a rotating body based on a flow rate and outputting a plurality of pulse signals having different phases. Determining means for determining the rotation direction of the rotating body from the output pulse signal of the means, sampling means for sampling the output pulse signal of the rotation detecting means, and comparing the sampling result of the sampling means with the normal sampling result to determine that the abnormality has occurred. An adjusting means for adjusting the sampling period of the sampling means when the judgment is made.

[0018]

In such a configuration, the sampling means,
The pulse signals output from the plurality of rotation detectors having different phases are sampled, and the rotation direction of the rotating body is detected by the discriminator from the sampling results. At this time, when the obtained sampling result is determined to be abnormal as compared with the normal sampling result, the adjusting means adjusts the sampling cycle of the sampling means, so that it is not necessary to always shorten the sampling cycle, and Erroneous determination of the rotation direction of the body can be prevented.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. Note that the same components as those in the related art are denoted by the same reference numerals and description thereof is omitted. FIG. 1 is a configuration diagram showing a first embodiment of an electronic water meter according to the present invention. In the figure,
Rotation detectors 10A and 10B detect the rotation of the rotating body based on the flow rate and output pulse signals having different phases, similarly to the conventional rotation detector shown in FIG. And Japanese Patent Laid-Open No. 6-6
As indicated by 6615, the switches 4A, 4 operated by the CPU 3 output the output pulse signals of the rotation detectors 10A, 10B.
Sampling is performed by controlling the opening and closing of B. This sampling result is monitored by the sampling result monitoring circuit 11.

In such a configuration, as shown in FIG. 2A, rotation detectors (for example, magnetic sensors) 10A, 10B
When the phases of the two output pulses Pa and Pb are extremely deviated from each other, the monitored sampling results Pas and Pbs are as shown in Table 3, and compared with Table 2, the sampling timings (7) to (8) In both, Pas and Pbs are changing. In such a state, (Pas, Pbs)
= (1,0) → (0,1) cannot be determined whether the change is due to normal rotation or reverse rotation, and the rotation direction of the rotating body may be erroneously determined.

Therefore, the sampling period follows the change in the status of the two output pulses Pa and Pb, and the sampling results shown in Table 2 are obtained.
As shown in (2), the CPU 3 shortens the sampling cycle. This can prevent erroneous determination of the rotation direction of the rotating body. Then, when the phase difference between the two output pulses Pa and Pb returns to the original state and the sampling result returns to the normal state as shown in Table 2, the sampling period also returns to the original state.

FIG. 3 shows a second embodiment.
When the phases of the two output pulses Pa and Pb of the rotation detectors 10A and 10B are extremely shifted as shown in FIG.
At 3, the sampling period is shortened. But the rotation detector
The output of 10A and 10B may include an irregular abnormal pulse due to the vibration of the rotating body other than the magnetic detection pulse due to the rotation of the normal magnet, and therefore two output pulses Pa and Pb of the rotation detectors 10A and 10B. Sampling results Pas, Pbs
Even if there is one sampling timing that changes at a time, the original normal state as shown in Table 2 may be immediately restored.

For this reason, the CPU 3 is provided with a storage section 6c for storing the number of times such a state continues, and the sampling period is shortened as shown in FIG. And, as a result of sampling, Table 2
When the normal state as shown in (1) is obtained continuously for the set number of times, the sampling cycle is returned to the original state.

FIG. 5 is a block diagram showing a third embodiment, in which two output pulses Pa, Pa of the rotation detectors 10A and 10B are shown.
When the phase of Pb is extremely shifted as shown in FIG. 6A, the sampling period is shortened as shown in FIG. 6B. However, in this case, the change in the status of the two output pulses Pa and Pb of the two rotation detectors 10A and 10B cannot be completely followed only by changing the sampling cycle once.

For this reason, the sampling cycle selection circuit 12 uses the sampling cycle selection circuit 12 until the change of the status of the two output pulses Pa and Pb can be followed within the set number of times in the range shown in FIG.
The sampling period is gradually shortened as shown in FIG.
Then, as the phase shift between the two output pulses Pb, Pb becomes smaller and the sampling result becomes as shown in Table 2, the sampling period is also gradually reduced from FIG. 6 (c) to FIG. 6 (b). Back to.

FIG. 7 is a block diagram showing a fourth embodiment, in which sampling is performed for an extreme phase shift between two output pulses Pa and Pb of the rotation detectors 10A and 10B as shown in FIG. Not only changing the cycle of the rotation, but also correcting the rotation direction of the rotating body and correcting the counting error of the integrated value of the flow rate when the sampling cannot follow the change in the status of the two output pulses Pa and Pb. .

That is, when the sampling results Pas and Pbs of the two output pulses Pa and Pb are different from the previous status, the previous status is stored.
When the sampling can follow the change of the status of the two output pulses Pa and Pb, the rotation is corrected by the rotation direction correction unit 6d and the integrated value correction unit 6e of the CPU 3 based on the stored sampling result. Correct the direction of rotation of the body and correct the error in the integrated value of the flow rate.

As described above, in an electronic water meter that uses a magnetoresistive element as a rotation detector for detecting the rotation direction of an impeller and intermittently drives the magnetoresistive element, the function of changing the sampling period of the magnetic sensor is provided. With this configuration, sampling can be performed at a sampling cycle that sequentially corresponds to the phase difference between the output pulses of the two magnetic sensors, thereby preventing erroneous determination of the rotation direction of the impeller and erroneous counting of the integrated value of the flow rate. . Further, it is possible to provide a low-current-consumption circuit capable of driving a meter for a long time with a relatively small capacity battery.

In addition, this makes it possible to secure long-term reliability of the meter by reducing the size of the case and circuit board accompanying the downsizing of the built-in battery and reducing the current consumption.

[0030]

As described above, according to the present invention, a plurality of rotation detecting means for detecting rotation of a rotating body based on a flow rate and outputting a plurality of pulse signals having different phases, and an output pulse signal of the rotation detecting means. Discriminating means for discriminating the rotation direction of the rotator, sampling means for sampling the output pulse signal of the rotation detecting means, and comparing the sampling result of the sampling means with the sampling result at the time of normal operation, when it is determined that there is abnormality. Since the adjusting means for adjusting the sampling period of the sampling means is provided, the current consumption can be reduced efficiently and a highly accurate electronic water meter can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an electronic water meter according to the present invention.

FIG. 2 is a diagram for explaining the operation of FIG. 1;

FIG. 3 is a configuration diagram showing a second embodiment of the electronic water meter according to the present invention.

FIG. 4 is a diagram for explaining the operation of FIG. 3;

FIG. 5 is a configuration diagram showing a third embodiment of the electronic water meter according to the present invention.

FIG. 6 is a view for explaining the operation of FIG. 5;

FIG. 7 is a configuration diagram showing a fourth embodiment of the electronic water meter according to the present invention.

FIG. 8 is a diagram for explaining the operation of FIG. 7;

FIG. 9 is a configuration diagram of a conventional electronic water meter.

FIG. 10 is a view for explaining the operation of FIG. 9;

[Explanation of symbols]

3: CPU, 10A, 10B: rotation detector, 11: sampling result monitoring circuit

Claims (4)

(57) [Claims] 1. A plurality of rotation detecting means for detecting rotation of a rotating body based on a flow rate and outputting a plurality of pulse signals having different phases, and determining a rotating direction of the rotating body from output pulse signals of the rotation detecting means. Determining means for sampling, a sampling means for sampling an output pulse signal of the rotation detecting means, and a sampling cycle of the sampling means when the sampling result of the sampling means is compared with a sampling result in a normal state and it is determined that there is an abnormality. Electronic water meter having an adjusting means for adjusting the temperature. 2. A plurality of rotation detecting means for detecting rotation of a rotating body based on a flow rate and outputting a plurality of pulse signals having different phases, and determining a rotating direction of the rotating body from output pulse signals of the rotation detecting means. Determining means, sampling means for sampling the output pulse signal of the rotation detecting means, storage means for comparing the sampling result of this sampling means and the normal sampling result and storing the number of times determined to be abnormal, An electronic water meter having adjusting means for adjusting the sampling cycle of the sampling means when the number of storages in the storage means reaches a predetermined number. 3. The electronic water meter according to claim 1, wherein the adjusting unit adjusts a sampling cycle of the sampling unit in a stepwise manner. 4. A control means for correcting the rotation direction of the rotating body and the integrated value of the flow rate determined by the determining means when the sampling result of the sampling means returns from abnormal to normal. The electronic water meter according to any one of claims 1 to 3.