JPH03206917A - Flowmeter - Google Patents

Abstract

PURPOSE:To achieve low power consumption by judging the forward and reverse rotations only in a low-rotation region, and making the frequency of the sampling pulses of either one sensor lower than that of the other sensor. CONSTITUTION:The output pulse of an oscillator 12 is converted into the pulse having the short width with a monostable circuit 13. A frequency divider 14 decreases the frequency of the output pulses from the oscillator, e.g. 500 Hz, to 100 Hz. The sampling pulses from the circuit 13 and the frequency divider 14 are applied as the currents and the voltages for sensor parts 1 and 6. The phases of the output signals of the sensor parts 1 and 6 are compared so as to judge forward rotation or reverse rotation. The output signal of the sensor 1 is added at the time of the forward rotation and subtracted at the time of the reverse rotation. Thus the computation is performed. At this time, a frequency f2 which is applied to the sensor part 6 is made lower than a frequency f1 of the sampling pulses applied on the sensor part 1. At the time of high-speed rotation when the number of rotations exceeds a specified value, the judgment for the forward and reverse rotations is not performed. The output of the sensor part 1 is added or subtracted based on the rotating direction immediately before the number of rotations exceeds the specified value. Thus the computation is performed. For example, when the rotating direction immediately before is the forward rotation, the outputs of the sensor part 1 are continuously added.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic flowmeter such as a water meter or a gas meter.

[Prior art] In flowmeters such as water meters and gas meters, the rotation of a rotating body such as an impeller is detected by a magneto-electric conversion element and converted into an electrical signal, and this electrical signal is counted and integrated to be used in water supply or gas fields. An electronic type that measures the amount used is used.

In such electronic flowmeters, when a rotating body such as an impeller is rotating in the normal direction, the integrating section performs an adding operation, and when the rotating body is rotating in the reverse direction, the integrating section performs a subtracting operation. For this purpose, whether the rotation of the rotating body is normal or reverse is detected, and the integrator is added or subtracted.

To detect whether the rotation of the rotating body is normal or reverse, two sensor sections for detecting rotation are provided, and the output signal of one sensor section is 90 degrees electrical angle higher than the output signal of the other sensor section.
In order to obtain a signal that is ahead of the others, the sensor of one sensor section is arranged with its position shifted from the sensor of the other sensor section in the rotational direction, and the phases of the output signals of both sensor sections are compared. This is done using a forward/reverse discrimination circuit that determines whether the rotation is forward or reverse depending on which sensor section's output signal is leading in phase.

Since such electronic meters are battery-powered, C-MOS integrated circuits are used exclusively to reduce power consumption and extend battery life.

Among C-MOS integrated circuits, digital circuits can reduce power consumption, but analog circuits, especially amplifier circuits used in the waveform shaping circuit of the sensor section and bridge circuits containing magnetoelectric conversion elements, still consume a large amount of power. . Therefore, in order to reduce the power consumption of such a sensor section, a sampling method is used in which the power supply voltage is applied to the sensor section intermittently for short periods of time to reduce the average current. This sampling method is also called a time division method.

Generally, in order to accurately detect the rotation speed, it is necessary to set the frequency of the sampling pulse to at least twice the rotation speed of the rotating body, but in flowmeters such as water meters and gas meters, Since it is necessary to determine whether the rotation is forward or reverse and add or subtract the rotation signal, more detailed sampling is performed. Specifically, the sensor section was intermittently driven with a sampling pulse of 1000 Hz, which is 10 times the highest frequency of the rotating body.

[Problem to be solved by the invention]

In the above conventional technology, a C-MOS integrated circuit is used and the sensor section is driven for sampling with a sampling pulse, but there is a limit to reducing the frequency of the sampling pulse, and moreover, the two sensor sections are connected to the power supply voltage. Because of the need to supply power, sufficient reductions in power consumption have not been achieved.

In view of the above, an object of the present invention is to provide an electronic flow rate with lower power consumption.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a rotating body (11)
first and second sensors (1) and (6) with different output signals provided to distinguish between forward and reverse rotation, and a sampling pulse generation circuit that applies power supply voltage to these sensor sections intermittently for short periods of time. and both the sensor parts (1) and (6).
In the flowmeter, the phase of the output signal of the sensor section is compared to determine whether the rotation is normal or reverse, and the output signal of one of the sensor sections (1) is added during normal rotation and subtracted during reverse rotation to be integrated. The frequency f2 of the sampling pulse applied to the second sensor part (6) is lower than the frequency f2 of the sampling pulse applied to the first sensor part (1), and when the rotation speed exceeds a certain value, The output of the first sensor section (1) is added or subtracted and integrated based on the direction of rotation immediately before the rotation speed exceeds the certain value, without performing forward/reverse determination.

(Function) When the rotation speed of the rotating body is below a certain value, both sensor parts (1
) and (6) are compared to determine whether the rotation is forward or reverse, and depending on the result of the forward/reverse determination, the rotation signal is added or subtracted and integrated.

When the number of rotations exceeds a certain value, the output of the first sensor section (1) is added or subtracted and integrated based on the direction of rotation exceeded. For example, if the direction of rotation immediately before the rotational speed exceeds a certain value is normal rotation, after the certain value is exceeded, the output of the second sensor section is ignored and the output of the first sensor section is continuously added.

〔Example〕

In FIG. 1, l is the I-th sensor section, ! ! It consists of a conversion element 2, a voltage dividing resistor 3.4 connected to the magnetoelectric conversion element 2 to form a bridge circuit, and an amplifier circuit 5 for amplifying the output signal of the bridge circuit. Reference numeral 6 designates a second sensor section, which includes a magnetoelectric conversion element 7, a voltage dividing resistor 8.9 connected to the magnetoelectric conversion element 7 to form a bridge circuit, and an amplifier circuit 10 for amplifying the output signal of this bridge circuit. It consists of The magnetoelectric conversion elements 2 and 7 function as sensors that convert the rotation of the rotating body 11 into electrical signals. Magnetoelectric conversion element 2
and 7 are arranged with their phases shifted in the rotational direction of the rotating body 11 so as to obtain electrical signals with a phase difference of 90 degrees from each other. 12 is a rectangular wave oscillator with a frequency of 500 Hz, and the period T of its output pulse is 2 mS.

13 is a monostable circuit that converts the output pulse of the oscillator 12 into a short width pulse, and the period of the output pulse is 11. JIT+
is set to be 2 mS, and the frequency r1 is set to be 500 Hz, much shorter than the period T.
14 is a frequency divider with a frequency division ratio of 1/5, which changes the frequency of the output pulse of the oscillator 12 from 500 Hz to 100 Hz. 15 is a monostable circuit that converts the output pulse with the divided period 14 into a pulse with a short width t, and the output pulse of this monostable circuit has a frequency f
2 is 100 Hz, the period T2 is 10 mS, and the pulse width is t. Sampling pulses from the monostable circuits 13 and 14 are applied as power supply voltages to the first and second sensor sections 1 and 6, respectively, to drive these sensor sections. 16
is a high-speed detection circuit, and from the output signal of the first sensor section 1,
It is determined whether the rotational speed of the rotating body l1 exceeds a certain value, and the determination result is input into the microcomputer 17. The output signals of the first and second sensor units 1 and 6 are manually input to a microcomputer 17. The microcomputer 17 compares the phase relationship of the output signals from the first and second sensor parts to determine whether the rotation is normal or reverse, and when the rotation is normal, the output signal of the first sensor part 1 is The number of rotations of the rotary body 11 is summed by adding it up and subtracting it when the rotation is reversed, taking into account the forward and reverse rotations. When a signal indicating that the number of rotations of the rotating body 11 exceeds a certain value is input from the high-speed detection circuit 16, the immediately previous rotation direction is retained and memorized, and the rotation direction is determined based on the retained rotation direction. The output signals of the first sensor unit are added or subtracted while the number exceeds a certain value and are integrated.

The constant value is determined from the lower frequency f2 of the sampling pulse that drives both sensor sections. Therefore, in the conventional technology, the sampling pulse frequency is 1000Hz.
Considering that the maximum rotation speed at which forward/reverse judgment could be made was 1/10 of the frequency of the sampling pulse, the first
In the example shown in the figure, 1/10 of the frequency fz of the sampling pulse of the second sensor section = 100 Hz is the maximum rotation speed at which forward/reverse determination is possible, and this maximum rotation speed is 1/10 of the maximum rotation speed of the conventional technology. .

With water meters, gas meters, etc., it is impossible for water meters, gas meters, etc. to reverse rotation when the flow rate exceeds a certain level, so it is only necessary to be able to determine whether the rotation is normal or reverse only in a relatively low flow range, and if the flow rate is higher than that, it is necessary to The principle of the present invention is to store and store the rotational direction of the rotational direction, and to add or subtract and integrate the rotational signal based on the retained rotational direction. By doing so, there is no need to determine whether the rotation is forward or reverse during high-speed rotation, so the frequency of the sampling pulse may be reduced accordingly. Therefore, in the embodiment, the sampling pulse of the l-th sensor section was lowered to 5001 Hz, which is half of the 1000 Hz of the prior art. As a result, power consumption is also reduced.

As in the prior art, both the first and second sensor sections are 100
Compared to driving with Hz sampling pulse,
In the above embodiment, the first sensor section is driven at 500 Hz and the second sensor section is driven at IOOHz, so that the power consumption of the sensor section can be significantly reduced. Since power consumption is approximately proportional to the number of sampling pulses, in this embodiment, the power consumption of the sensor unit is (500+100)/(IOOOX 2) = 0.3 compared to the conventional technology.
0, which was reduced to 30%.

In the above embodiment, the high-speed detection circuit 16 is provided separately from the microcomputer 17, but this function may be performed by the microcomputer 17.

Further, the function of holding and storing the rotational direction performed by the microcomputer 17 may be performed by providing a rotational direction holding circuit separately from the microcomputer 17.

(Effects of the Invention) Since the present invention is constructed as described above, there is no need to judge whether the rotation is forward or reverse in the high rotation range, so the sampling frequency can be lowered accordingly, and the forward/reverse judgment is only performed in the low rotation range. Furthermore, since the sampling pulse frequency of one sensor section is set lower than that of the other, power consumption can be further reduced by that amount, and as a battery-powered flowmeter, it is effective in improving battery life.

[Brief explanation of drawings]

FIG. 1 is an electrical circuit of an embodiment of the present invention. 1, 6...Sensor part, 11...Rotating body, 12...
Oscillator, 13. 15... Monostable circuit, 14... Frequency divider, 16... High-speed detection circuit, l7... Microphone mouth computer

Claims (1)

[Claims] First and second sensors (1) and (6) with different output signals are provided to distinguish between forward and reverse rotation of the rotating body (11), and a power supply voltage is intermittently applied to these sensor sections for short periods of time. The output signal from one of the sensor sections (1) is determined by comparing the phases of the output signals of the two sensor sections (1) and (6) to determine whether the rotation is normal or reverse rotation. In a flowmeter that adds up during normal rotation and subtracts during reverse rotation, the frequency f_1 of the sampling pulse applied to the first sensor section (1) is determined by
6) The frequency f_2 of the sampling pulse to be applied is lowered, and during high-speed rotation when the rotation speed exceeds a certain value, the rotation speed is determined based on the rotation direction immediately before the rotation speed exceeds the certain value, without performing forward/reverse determination A flow meter that integrates the output of a sensor section (1) by adding or subtracting the output.