JPH0311740Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fluid flow detection device that can easily detect whether or not fluid is currently flowing through a fluid guiding pipe.

[Technical background of the invention and its problems] Conventionally, as a means for detecting whether or not fluid is flowing through a pipe, a method in which a flow meter is interposed in the middle of the pipe has been exclusively adopted.

However, with the method of interposing a flowmeter, it can be installed with relatively simple work when installing new pipes, but when trying to install it on existing pipes, it is affected by the building and underground conditions, etc. is often extremely difficult. Furthermore, providing a flowmeter solely for the purpose of detecting whether or not fluid is flowing is inevitably economically disadvantageous since the flowmeter itself is generally expensive. This has a particularly large impact when configuring a home security system.

[Purpose of the invention] The present invention was created in view of the above circumstances, and its purpose is to be able to easily install it in piping, whether new or existing, and to allow fluid to flow through the piping. It is possible to accurately detect whether or not
The object of the present invention is to provide a fluid flow detection device that can contribute to the simplification of home security systems and the like.

[Structure of the invention] According to the invention, an acoustic sensor with a built-in piezoelectric element is attached to the outer surface of the fluid guiding pipe. The above-mentioned acoustic sensor is mounted near a position where sound is likely to be generated during fluid flow, such as a bend in a pipe or near a valve or a cock. Further, a transmitter that sends out an output pulse of a constant period, and an output signal outputted from the acoustic sensor for a time interval of the output pulse based on a time point at which the output pulse of the transmitter changes in a specific direction. means for transmitting an output when the proportion of the period of the output signal portion having an amplitude level above a certain value exceeds a predetermined value; and a period longer than the cycle of the oscillator from the time when the output is transmitted from the means; A determining device is provided, which comprises a means for performing a notification operation.

[Effects of the invention] As described above, in the device of the invention, an acoustic sensor with a built-in piezoelectric element is attached to the outer surface of the fluid guide pipe,
The sensor converts the sound that always occurs when fluid flows through the pipe into an electrical signal, and this electrical signal is sent to the determination device. Therefore, according to the present invention, it can be easily installed without special processing on the piping, regardless of whether it is newly installed or existing piping, and it is possible to perform flow detection without being subject to installation restrictions. can. Therefore, when incorporated into a home security system or the like, for example, it is possible to prevent the system from increasing in price. In addition, since the determination device is configured as described above, the ratio of the period of the output signal portion whose amplitude level is above a certain level among the output signals output from the acoustic sensor to the time interval of the output pulse of the oscillator is When the value is less than a predetermined value, no notification operation is performed. Therefore, even if acoustic noise enters the fluid guiding pipe from the outside for a short period of time, false detection due to the influence of this acoustic noise can be prevented, and a highly reliable detection device can be constructed.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described with reference to the drawings.

FIG. 1 schematically shows an example of detecting the flow of tap water using the device according to the present invention.

That is, in the figure, 1 indicates a water pipe, 2 indicates a valve, and 3 indicates a wall material that supports the pipe 1.

An acoustic sensor 11 is mounted on the outer surface of the pipe 1 and in a portion close to the valve 2. As shown in FIG. 2, this acoustic sensor 11 is made of a piezoelectric film 1 made of, for example, PVF ₂ , with electrodes on both sides.
An insulating sheet 13 is applied to one side of the metal plate 14a, which has an electromagnetic shielding function.
14b, and covered with metal plates 14a and 14b watertightly.
On one end side, in the cavity 15 formed between both metal plates, as shown as an equivalent circuit in FIG. A field effect transistor 16, a resistor 17, and a diode 18 are housed therein, and a three-core cable 19 connected thereto is drawn out from the cavity 15 in a liquid-tight manner. The acoustic sensor 11 is attached with its tip end wrapped around the outer peripheral surface of the pipe 1. In addition, in FIG. 2, 20 and 21 indicate insulating materials, and 22 indicates a joint wire.

Of the three core wires of the three-core cable 19, core wires 19a and 19 equivalently shown in FIG.
b is connected to a DC power supply (not shown), and core wire 1
9c and 19b are connected to a determination device 31, which will be described next.

The determination device 31 is configured as shown in FIG. That is, the core wire 19 of the acoustic sensor 11
The signal appearing between c and 19b is introduced into an amplifier 33 via a filter 32, and the signal amplified by this amplifier 33 is introduced into a window comparator 34, and when the signal from this window comparator 34 exceeds a predetermined level A pulse signal with a pulse width corresponding to the period is sent out. Then, the pulse signal sent from the window comparator 34 is introduced as an input pulse to the binary counter 35. The counter 35 is, for example,
It is reset at the falling edge of the output pulse of the oscillator 36, which sends out an output pulse with a period of 1 second and a width of 0.5 seconds. Then, the output of the final stage bit of the counter 35 and the output of the oscillator 36 are connected to a monostable multivibrator 38 via an AND gate 37.
is introduced as an input signal. The monostable multivibrator 38 is set to maintain an output output state for, for example, two seconds when an input signal is introduced. The output of the monostable multivibrator 38 is then given as a display control signal to the display device 39.

With such a configuration, if the valve 2 is now operated to discharge tap water, frictional noise will be generated in the pipe 1 due to the flow of tap water. According to experiments, the above-mentioned fricative noise is largest in the bent portion of the flow path, especially in the vicinity of the valve 2. Therefore, when water is supplied through the valve 2 as described above, the sound is detected by the acoustic sensor 11, and the output end of the acoustic sensor 11, that is, between the core wires 19c and 19b, as shown in _FIG.
As shown in the figure, a continuous signal with large amplitude appears. This signal is converted by the window comparator 34 into a pulse signal as shown in the figure. The pulse output of the window comparator 34 is counted by a counter 35. Since the counter 35 is set to be reset by the falling edge of the output pulse of the oscillator 26, the final bit will be "1" within the period (1 second) from the time it is reset until the next reset. ”, the output is sent out as shown in FIG. Therefore, as shown by X ₂ in Figure 5, 0.5
Sound that disappears within seconds, that is, noise, is so-called cut out by the above-described operation of the counter 35. Thus, when the final bit of the counter 35 is "1" and the output of the oscillator 36 is at a high level, the AND gate 37 opens, thereby driving the monostable multivibrator 38.
As a result, the display device 39 displays an indication that the current is flowing. Since the operating period of the monostable multivibrator 38 is set to 2 seconds, even if the flow stops for a very short time as shown by X ₃ in Figure 5 within 2 seconds, the flow will be displayed. continue the condition,
Furthermore, if the AND gate 37 is opened again within 2 seconds, the flow display state continues. Therefore, valve 2
When the pipe 1 is opened and tap water is flowing through the pipe 1, a display to that effect is reliably displayed on the display device 39.

In this case, since the acoustic sensor 11 is used, which can be installed on the pipe 1 by simply wrapping it around the outer circumference of the pipe 1, it can be easily installed on various types of pipes, whether new or existing. Therefore, a fluid flow detection device can be easily realized. Further, it is possible to prevent erroneous detection based on acoustic noise entering the pipe 1 from the outside, and it is possible to realize a highly reliable fluid flow detection device that is suitable for actual situations.

Note that the present invention is applicable not only to tap water but also to various types of flow detection. The piezoelectric element is not limited to a film-like element.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an example in which a fluid flow detection device according to an embodiment of the present invention is applied to tap water flow detection, and FIG. 2 is a cross-sectional view of an acoustic sensor in the same embodiment. 3 is an equivalent circuit diagram of the same acoustic sensor, and FIG. 4 is a configuration explanatory diagram of the determination device in the same embodiment.
FIG. 5 is a diagram showing waveforms of various parts in the same embodiment. 1... Piping, 11... Acoustic sensor, 31... Judgment device, 39... Display device.

Claims (1)

[Scope of utility model registration request] An acoustic sensor with a built-in piezoelectric element is installed on the outer surface of the fluid guide pipe and near the part where sound is generated inside when fluid flows through the fluid guide pipe, and sends out output pulses at a constant period. an oscillator that outputs an oscillator, and an output signal portion of the output signal outputted from the acoustic sensor that has an amplitude level above a certain level with respect to the time interval of the output pulse, based on the time point at which the output pulse of the oscillator changes in a specific direction. means for transmitting an output when a ratio of the period of the oscillator reaches a predetermined value or more; and means for performing a notification operation for a period equal to or longer than the cycle of the oscillator from the time when the output is transmitted from the means. A fluid flow detection device characterized by: