JPS628493Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a parent-child meter that accurately measures the flow rate of fluid with less error.

Generally, the range in which a flow meter such as a water meter or a gas meter can accurately measure is limited depending on its diameter, and it is difficult to measure from a minute flow rate to a large flow rate with a single meter. For this purpose, a parent-child meter with an auxiliary pipe has been developed, which is a combination of a large-diameter parent meter and a small-diameter child meter. In such a parent-child meter, four transmission lines are required to transmit the flow rate signals of the parent and child meters as electrical pulses to distant locations. A permanent magnet is attached to the rotating shaft of each parent and child meter, and a reed switch is placed close to each of these rotating permanent magnets.
Each reed switch of the parent and child meters is opened and closed at each constant rotation, converting it into an electric pulse signal (flow rate pulse) for each constant flow rate of each meter, and one 2-core cable is connected to each reed switch, resulting in a total of 4 The drawback was that it required a core transmission line, making the cable expensive.

In view of the above, this invention proposes a parent-child meter whose transmission line requires only one cable with two cores, and will be explained below based on the embodiments shown in the drawings.

Reference numeral 1 denotes a measuring section of a parent-child meter, and a known permanent magnet and a mechanism for rotating it are omitted and not shown. 2 is the reed switch of the parent meter,
3 is the reed switch of the secondary meter, 4 and 5 are diodes connected in series to reed switches 2 and 3 respectively, and the series connection of reed switch 2 and diode 4 of the parent meter is connected to the series connection of reed switch 3 and diode 5 of the secondary meter. The connection and diodes 4 and 5 are connected in parallel so that their directions are reversed, and one end of each of the two transmission lines L ₁ and L ₂ is connected to both ends of the connection, and the other end of the transmission line is located at a separate location. They are connected to the collectors of transistors Q ₁ and Q ₂ of receiver 6, respectively.
_R1 to _R4 are resistors, 7 and 8 are D-type flip-flops, and 9 is a buffer amplifier, which are connected as shown in the figure.

Note that only the main parts of the electric circuit of the receiver 6 are shown.

Reed switches 2 and 3 open and close at a speed proportional to the rotation speed of the corresponding permanent magnet, that is, the flow speed of each parent and child meter. The receiver 6 has a clock oscillator (not shown), and sampling pulses generated from the clock and having a phase difference of 180 degrees (half cycle) are applied to terminals A and B. Terminal A,
The voltage waveform of voltage B is shown in FIGS. 2A and 2B, and normally it is at the "H" level, and a sampling pulse at the "L" level is applied for a short time every period T. Terminal A
When a sampling pulse is applied to the transistor Q 2 , the transistor Q ₂ becomes conductive and its collector becomes “H” level. When the reed switch 2 is closed, the voltage is applied to the D-type flip-flop via the diode 4 and the reed switch 2. Applied to terminal D of 7,
At the same time, a sampling pulse is applied to the terminal CL of the D-type flip-flop 7, so that the D-type flip-flop 7 latches the state in which the reed switch 2 is closed as an "H" level. At this time,
Since transistor Q ₁ is cut off, if reed switch 2 of the parent meter is open, D
Since the terminal D of the flip-flop 7 is at the "L" level, the D-type flip-flop 8 latches the open state of the reed switch 2 as the "L" level. In this way, the D-type flip-flop 7
latches and stores the open/closed state of the reed switch 2 of the parent meter as an "H" or "L" level for each sampling pulse. The period of the sampling pulse is determined by the reed switches 2 and 3 of the parent or child meter.
It is set to be relatively shorter than the opening/closing cycle of When a sampling pulse is applied to terminal B,
Since the transistor _Q2 is in the cut-off state and the transistor _Q1 is conductive, the voltage of VDD is transmitted to the terminal D of the D-type flip-flop 8 through the reed switch 3 and the diode 5, and the D-type flip-flop 8 is connected to the reed switch 3. The open/closed state is latched and stored as an "H" or "L" level. Thus,
The flow rate pulse signals of the parent and child meters are reproduced at the Q output terminals of the D-type flip-flops 7 and 8. Since the rise and fall of this regenerated (latched) flow rate pulse signal are synchronized with the sampling pulses shown in Figure 2 A and B, the rise and fall of the regenerated pulse signal of the parent meter and child meter The falling and falling edges are not simultaneous, but are shifted by at least half the period T of the sampling pulse. Therefore, the rise of the reproduction pulse signals of the parent and child meters is detected by an edge detection circuit (not shown) to generate a short pulse signal, and this pulse signal is sent to both the parent meter and child meters via an OR gate (not shown). By counting with one counter circuit, the sum of the flow rate pulses of both the parent and child meters can be counted in an integrated manner.

As mentioned above, according to this invention, a reed switch with a diode connected in series is installed in the parent meter and the slave meter, and both ends of the series connection are connected in parallel with the diodes facing in opposite directions. Since the open/closed state of the reed switch of each parent and child meter is detected by changing the polarity of the voltage applied to both ends, there is an advantage that the flow rate pulses of both the parent and child meters can be transmitted using two transmission lines.

Note that in the embodiment, since the sampling pulse is a short pulse, less power is required for sampling.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit of an embodiment of this invention, and FIG. 2 is a timing chart explaining its operation. 1... Measuring unit, 2... Main meter reed switch, 3... Sub meter reed switch, 4, 5...
...Diode, 6...Receiver, 7, 8...D-type flip-flop, _L1 , _L2 ...Transmission line, _Q1 , _Q2 ...
...Transistor, A, B...Sampling pulse terminal.

Claims (1)

[Scope of utility model registration request] In a flowmeter with an auxiliary pipe, each parent and child meter is equipped with a diode connected in series to a reed switch that detects the rotation of the permanent magnet installed on the rotating shaft of each parent and child meter, and the direction of the diode is reversed at both ends of the series connection. To detect the open/closed state of the reed switch provided on each parent and child meter by connecting them in parallel so that A parent-child meter featuring