JPH0894401A - Electronic water meter - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a highly accurate electronic water meter that can efficiently reduce current consumption. [Configuration] Switches 4A, 4B by the CPU 3 when necessary
Is closed and current is supplied to the rotation detectors 10A and 10B,
The rotation detectors 10A and 10B detect the rotation of the rotating body based on the flow rate and output pulse signals having different phases. This pulse signal is sampled in order to determine the rotation direction of the rotating body. The sampling result monitoring circuit 11 compares the sampling result with the sampling result in the normal state, and shortens the sampling cycle when it is determined to be abnormal.

Description

Detailed Description of the Invention

[0001]

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 running water flowing inside, as disclosed in, for example, JP-A-54-141166. Two pulse outputs with different phases are obtained in order to detect the rotation direction (forward rotation and reverse rotation) of the impeller that rotates.

Such an electronic water meter will be described with reference to FIG. In the figure, a pair of detectors 1A and 1B using magnetoresistive elements are radially arranged on a substrate so that an included angle of 45 ° is formed with respect to an axis, and rotation detection circuits 9A and 9B are incorporated in the substrate. Has been. In the rotation detection circuits 9A and 9B, electric power is constantly supplied to the detectors 1A and 1B and the comparators 2A and 2B, and the detectors 1A and 1B are supplied.
The pulses output from A and 1B are detected.

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

On the negative side of the comparator 2B, the cathode side of the Zener diode 6B is connected between ground conductors (not shown), and when a signal of passage of the impeller is input from the detector 1B, as shown in FIG. 10 (a). A square wave pulse Pa to C
Output to PU3.

When the shaft of the impeller further rotates clockwise,
The voltage between the ground potential and the ground potential due to the change in the resistivity of the magnetoresistive element inside the detector 1A, which is arranged at a 45 ° clockwise angle with respect to the detector 1B, is stored in the rotation detection circuit 9A. Input on the positive side. Then, the comparator 2A outputs the rectangular wave pulse Pa to the CPU 3 at the timing of the central portion of the pulse Pa of the comparator 2B.
To enter. Hereinafter, this is repeated for each rotation of the shaft 8. The negative side of the comparator 2A is also connected to the cathode side of the Zener diode 6A, like the comparator 2B.

On the other hand, the other side of the detectors 1A and 1B, one side of which is connected to the ground bus, and the respective comparators 2A, 2B and C.
The power terminals of PU3 are connected to the battery power source 5, respectively.

Further, FIG. 10 (b) shows the output from each comparator 2A, 2B when the shaft of the impeller is reversed in the counterclockwise direction due to, for example, the rupture of the water pipe on the upstream side of the electronic water meter. In the figure which shows the timing of the pulses Pa and Pb,
Contrary to FIG. 10A, the pulse Pb is generated at the center of the pulse Pa.
Is standing up.

Therefore, the CPU 3 determines whether the impeller rotates normally or reversely according to the matrix shown in Table 1 according to the timings and modes of the pulses Pa and Pb input from the comparators 2A and 2B.

[0010]

[Table 1]

That is, when the pulse Pa is rising or before and after it, and the pulse Pa is "high", or when the pulse Pa is rising or before and after it, and the pulse Pb is "low", the forward rotation is determined. . When the pulse Pa is rising or before and after it, and the pulse Pb is "low", or when the pulse Pa is rising or before and after it, and the pulse Pb is "high", it is determined to be reverse.

Further, in order to reduce the consumption of the battery serving as the power source 5, the load side of the power source 5 is provided with switches 4A and 4B, respectively, as shown in Japanese Patent Laid-Open No. 6-66615.
Detectors 1A, 1B and comparators 2A, 2 only when needed
B and the CPU 3 are energized.

[0013]

Such an electronic water meter, as disclosed in Japanese Patent Laid-Open No. 6-66615, has a normal rotation when sampling is performed at a cycle that follows changes in two output pulses.・ The status of sampling results when reversing changes as shown in Table 2. However, if the phases of the two pulses are extremely deviated due to errors such as the position and sensitivity of the rotation detector, the magnetization of the magnet, etc., the sampling can follow the changes in the status of the two output pulses as shown in Table 3, for example. Instead, there is a possibility that the forward and reverse of the rotation direction of the rotating body may be erroneously determined.

For this reason, it is necessary to always perform sampling at a very short interval in consideration of the phase shift between the two output pulses. However, when the difference between the two output pulses is not so large, an extra current is consumed by the rotation detector, and it is not possible to achieve a sufficiently efficient low current consumption.

[0015]

[Table 2]

[0016]

[Table 3] An object of the present invention is to provide an electronic water meter with high accuracy that can efficiently reduce current consumption.

[0017]

In order to achieve the above object, the present invention provides 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 rotation detecting means. A discriminating means for discriminating the rotation direction of the rotating body from the output pulse signal of the means; a sampling means for sampling the output pulse signal of the rotation detecting means; The gist is to have an adjusting unit that adjusts the sampling period of the sampling unit when it is determined.

[0018]

In this structure, the sampling means,
The pulse signals output from the plurality of rotation detecting means and having different phases are sampled, and the discriminating means detects the rotation direction of the rotating body from the sampling results. At this time, when the obtained sampling result is compared with the normal sampling result and judged to be abnormal, the adjusting means adjusts the sampling cycle of the sampling means, so that it is not necessary to shorten the sampling cycle at all times and further rotation is performed. It is possible to prevent erroneous determination of the body rotation direction.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the same components as those in the related art are designated by the same reference numerals and the description thereof will be omitted. FIG. 1 is a configuration diagram showing a first embodiment of an electronic water meter of the present invention. In the figure,
The rotation detectors 10A and 10B detect rotation of the rotating body based on the flow rate and output pulse signals having different phases, as in the conventional detectors of FIG. And, JP-A-6-6
As indicated by 6615, the switches 4A and 4 operated by the CPU 3 to control the output pulse signals of the rotation detectors 10A and 10B.
Sampling is performed by the open / close control of B. The sampling result is monitored by the sampling result monitoring circuit 11.

In such a structure, 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 shifted, 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 change. When this happens, (Pas, Pbs)
Since it cannot be determined whether the change of = (1,0) → (0,1) is due to normal rotation or reverse rotation, there is a possibility that the rotation direction of the rotating body is erroneously determined.

Therefore, the sampling cycle follows the change in the status of the two output pulses Pa and Pb, and the sampling result as shown in Table 2 is obtained so that the sampling result shown in FIG.
As shown in, the CPU 3 shortens the sampling period. This can prevent erroneous determination of the rotation direction of the rotating body. Then, when the phase shift 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 deviated as shown in FIG.
At 3, the sampling cycle is shortened. But the rotation detector
As the outputs of 10A and 10B, an irregular abnormal pulse due to the vibration of the rotating body other than the magnetic detection pulse due to the usual rotation of the magnet can be considered, so the two output pulses Pa and Pb of the rotation detectors 10A and 10B Sampling result of Pas, Pbs
Even if there is one sampling timing at which the value changes at one time, it may immediately return to the original normal state as shown in Table 2.

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

Next, FIG. 5 is a block diagram showing a third embodiment, in which two output pulses Pa of the rotation detectors 10A and 10B,
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, it is not possible to completely follow the change in the status of the two output pulses Pa and Pb of the rotation detectors 10A and 10B by only changing the sampling cycle once.

Therefore, until the change of the statuses of the two output pulses Pa and Pb can be followed within the set range number of times, the sampling cycle selection circuit 12 causes the sampling cycle selection circuit 12 shown in FIG.
As shown in, the sampling period is gradually shortened.
Then, as the phase shift between the two output pulses Pb and Pb becomes smaller and the sampling result becomes as shown in Table 2, the sampling period is also gradually changed from that shown in FIG. 6C to FIG. 6B. I will return to.

Next, FIG. 7 is a block diagram showing a fourth embodiment, in which sampling is performed for an extreme phase shift between the two output pulses Pa and Pb of the rotation detectors 10A and 10B as shown in FIG. Not only has the function of changing the cycle but also the function of correcting the rotating direction of the rotating body and correcting the count error of the integrated value of the flow rate when the sampling cannot follow the change of 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 both different from the previous status, the previous status is stored,
At the time when the sampling can follow the change of the status of the two output pulses Pa and Pb, the rotation direction correction unit 6d and the integrated value correction unit 6e of the CPU 3 rotate by calculation based on the stored sampling result. Correct the rotation direction of the body and correct the error in the integrated value of the flow rate.

As described above, in the electronic water meter in which the magnetoresistive element is used for the rotation detector for detecting the rotating direction of the impeller and the magnetoresistive element is intermittently driven, the sampling cycle of the magnetic sensor can be varied. With this, sampling can be performed at a sampling cycle that sequentially corresponds to the phase shift of the output pulses of the two magnetic sensors, and it is possible to prevent erroneous determination of the rotating 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 that can drive the meter for a long period of time with a battery having a comparatively small capacity and that does not waste.

Further, by doing so, it is possible to secure the long-term reliability of the meter due to the cost reduction due to the miniaturization of the case and the circuit board accompanying the miniaturization of the built-in battery and the low 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 output pulse signals of the rotation detecting means. When it is determined to be abnormal by comparing the sampling result of the sampling means with the sampling means for sampling the output pulse signal of the rotation detecting means Since the adjusting means for adjusting the sampling cycle of the sampling means is provided, it is possible to efficiently reduce the current consumption and obtain a highly accurate electronic water meter.

[Brief description of drawings]

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

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

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

FIG. 6 is a diagram for explaining the operation of [FIG. 5].

FIG. 7 is a configuration diagram showing a fourth embodiment of an electronic water meter of 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 diagram for explaining the operation of [FIG. 9].

[Explanation of symbols]

3 ... CPU, 10A, 10B ... Rotation detector, 11 ... Sampling result monitoring circuit

Claims (4)

[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 a rotation direction of the rotating body is discriminated from output pulse signals of the rotation detecting means. Discriminating means, sampling means for sampling the 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 the sampling result at the normal time and it is determined to be abnormal. An electronic water meter having an adjusting means for adjusting. 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 a rotation direction of the rotating body is discriminated from output pulse signals of the rotation detecting means. Discriminating means, sampling means for sampling the output pulse signal of the rotation detecting means, and storing means for storing the number of times judged to be abnormal by comparing the sampling result of the sampling means with the sampling result at the normal time, An electronic water meter having an adjusting means for adjusting the sampling cycle of the sampling means when the number of times of storage of the storage means reaches a predetermined number. 3. The electronic water meter according to claim 1, wherein the adjusting unit adjusts the sampling cycle of the sampling unit in a stepwise manner. 4. A control means for correcting the rotating direction of the rotating body and the integrated value of the flow rate, which are discriminated by the discriminating means, when the sampling result of the sampling means returns from an abnormality to a normal state. The electronic water meter according to any one of claims 1 to 3.