JPH0124710Y2 - - Google Patents

Description

[Detailed description of the invention] To read the measured value of a water meter or gas meter from a remote location, a start signal for reading is sent to the meter, and the meter receives this start signal and transmits the data. A method is adopted in which a command is given to an electronic circuit within the meter, and the electronic circuit transmits the measured value as a flow rate signal. Some of these known remote readout devices have a transmission cable that can be detached from the meter by connecting it to a connector, but they have the disadvantage that noise from the outside can penetrate the electronic circuit inside the meter through the cable, and the water meter When used in a submerged environment, the disadvantage is that it is difficult to connect and disconnect the connector underwater.

In view of the above, this idea was developed by isolating the transmission cable from the electronic circuit inside the meter so that the transmission cable can be attached and detached even underwater, and to prevent the intrusion of electrical noise from the outside, thereby achieving energy efficient transmission. The object of the present invention is to provide a remote readout device that is easy to handle.

Next, this invention will be explained with reference to the drawings.

In Fig. 1, 1 is a measuring instrument, 2 is a reading board placed apart from the measuring instrument, 3 is a transmission line, and 4 is an inductive coupling means provided at one end of the transmission line. Not shown in Figure 1. When the reading switch 5 of the reading board 2 is closed, an AC voltage is applied from the AC voltage source 6 to the coil 7 of the inductive coupling means 4. Note that the resistance R ₁ is set to a relatively small resistance value compared to the impedance of the coil 7. The coil 7 is wound around a yoke 8, and a yoke 9 facing the yoke 8 is provided on the measuring instrument 1, and the yokes 8 and 9 are butted against each other to form a closed magnetic circuit. There is. York 9
A coil 10 is wound around the yoke, and these two yokes and the two coils constitute an inductive coupling having a structure similar to that of a transformer. The inductive coupling means 4 constituting half of this inductive coupling can be attached to or removed from the measuring instrument 1 facing the yoke 9. When the reading switch 5 is closed as described above, the coil 7
An alternating current voltage is applied to the coil 10, and an induced voltage is generated in the other coil 10. Voltage detection means 11 detects this induced voltage and sends a transmission command to a one-shot multivibrator to be described later in the electronic circuit of the meter. The voltage detection means 11 has a high internal resistance,
Since it consumes almost no current, a very small current is generated at this time.
I ₁ flows, and a minute current kI ₁ flows in the transmission line 3.
Note that k is a constant determined by the winding ratio of inductive coupling, etc. When the meter electronic circuit receives a transmission command, the electronic circuit converts the measured value into a serial digital signal as a flow rate signal, and turns the switch 12 ON or OFF depending on whether the flow rate signal is "1" or "0". When the switch 12 is turned on, a current _I2 larger than _I1 flows through the coil 10. Therefore, a current of kI ₂ flows through the coil 7, and currents of kI ₂ and kI ₁ flow through the resistor R ₁ inserted in series in the transmission line in response to the on/off state of the switch 12. The voltage drop across the resistor _R1 due to this current is detected by the detection circuit 13, and the measured value "1" or "0" can be read as a voltage change in the serial digital signal, that is, the flow rate signal.

In the case of FIG. 2, the voltage detection means 11 is connected to the rectifier 1.
1a and a resistor 11b, and a switch composed of an active element (transistor) 14 is connected in parallel with the resistor 11b. R ₂ is a current limiting resistor. The values of resistors R ₂ and 11b are made relatively larger than the resistance values of the coils, and the winding ratio of both coils is set to 1:1. When a voltage with an effective value of 5V is applied from the reading side, a direct current of approximately 7V is generated across the resistor 11b. If resistor _R2 is 14KΩ and 11b is 70KΩ, coil 10 is turned on and off by transistor 14.
A current of 500μA and 100μA flows through the sensor, and almost the same current flows through the detection resistor on the reading side, allowing signal transmission.

Fig. 3 differs from Fig. 2 in that a battery 6' is used as the voltage source for the reading board 2, and an efficient transmitter 15 is provided near the end of the transmission line 3 to convert direct current to alternating current. There is. In this case, the current consumption Io of the oscillator 15 is added to the signal currents kI ₁ and kI ₂ flowing through the transmission path, but if it is set as Io<<kI ₁ and kI ₂ , there is substantially no effect. Using direct current transmission in this way is more convenient in terms of circuit separation, etc.

FIG. 4 shows an example of the internal configuration of the meter 1, which is a water meter. Blade wheel 1 with magnet 16 attached
When 7 rotates according to the flow rate, reed switch 1
8 opens and closes, and the frequency divider 19 converts this opening/closing signal into pulses for each unit flow rate, and the counter 20 integrates and measures the pulses. In the embodiment, the counter 20 has eight decimal digits.
A BCD (binary coded decimal) counter is used. In other words, it is a counter with 4 bits per decimal digit, totaling 32 bits, and always outputs 32 bits of accumulated content. Although not shown in FIG. 4, when displaying the accumulated contents, the contents of the counter 20 are made visible on a liquid crystal display or the like through a BCD-7 segment decoder. When you close the switch on the reading board located far away and start it up, a minute current of i ₁ = e/R ₁ + R ₃ + R ₄ flows through the transmission line 3, and the voltage across the resistor R ₁ of the reading board 2 is " 0”
level voltage is generated. Note that e represents the voltages R ₃ and R ₄ of the battery 6', respectively, representing the resistance 11b and the reciprocating line resistance of the transmission line 3, and the winding ratio of the coils 8 and 9 is considered to be 1:1. At this time, the voltage shown at a in FIG. 5 generated across the resistor 11b operates the one-shot multivibrator 22 as a transmission command to output one pulse shown at b in the figure. The contents of are transferred to the 32-bit parallel-in serial-out shift register 21. On the other hand, at the falling edge of the pulse of the one-shot multivibrator 22, the clock generator 23 starts operating and generates 32 clocks as shown in FIG. 5c. This clock is applied to the clock input of the shift register 21, and the integrated measurement values stored in the shift register 21 are sequentially output from left to right according to the number of clocks. (See timing chart d in Figure 5) This signal is applied to the base of the transistor 14, and the transistor 14 conducts (turns on) only when the signal is at the "H" level among the 32 bits, and the transmission line is connected to the i A current of ₂ = e/(R ₂ R ₃ /R ₂ +R ₃ )+R ₁ +R ₄ flows.

i ₁ and i ₂ are the line currents flowing in the transmission line 3, which are captured by the reading board as voltage drops across the resistor R ₁ ,
The "H" or "L" of each bit of the integrated measurement value is read. Since the number of digits of the water meter is known in advance and the signal transmission speed is determined, if the reading switch 5 is opened after a certain period of time required for reading has elapsed, the transmission command disappears and the reading ends. When the 32-bit output of the counter 20 is as shown in Fig. 5f, the signal current flowing through the resistor _R1 is as shown in Fig. 5f.
become that way. When performing double transmission to improve transmission quality, the serial output of the shift register 21 is connected to the serial input, and the number of clocks generated is 32 bits x n times, thereby making it possible to transmit the same data n times. If you want to transmit the water meter number or data start and end signals, extend the shift register forward and backward (left and right in the diagram) by the number of bits of the data, and connect the parallel inputs to the power supply inside the water meter by wire. V+, GND (ground)
By connecting the clock generated by the clock generator 23 to the same number of bits as the shift register, the meter number, data start, and end signals can be detected on the reading board side, and the reading switch 5 is activated by the end signal. Since it can be turned off, data can be transferred even if the reading board and water meter are asynchronous in time.

In Figure 6, 100 is an electronic water meter;
The rotation of the impeller 17 is counted by the electronic circuit 200 and stored as a measured value, and when a reading activation signal is received via the cable (transmission line) 3, the transmission command activates the circuit and the measured value is recorded as described above. to be sent out and transferred via the cable. A yoke 9 constituting the inductive coupling is fixed to a case 201 of the electronic circuit in a watertight manner, and a yoke 8 is disposed so as to butt against this yoke 9, and is attached to the case 201 with screws 101. 102 is a potted epoxy resin. Reference numeral 103 is a glass window for viewing the measured values displayed on the display element of the electronic circuit.

As is clear from the above explanation, according to this invention, there is no electrical connection by mechanical contact between the measuring instrument such as a meter and the cable, so there is little risk of electrical noise intruding, and it is easy to create a watertight structure. The measuring instrument and the transmission cable can be attached and detached underwater. In addition, data transmission is more energy efficient than optical coupling, etc., and depending on the design of the inductively coupled yoke and coil, high frequencies up to about 10KHz can be easily transmitted, so data can be sent at high speeds of about 1000 baud. This is possible and extremely effective in practice.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams explaining the basic concept of this invention, Figure 4 is a diagram showing an example of implementing this invention to a water meter, and Figure 5 is a timing chart explaining the operation of this invention. , FIG. 6 is a partial vertical sectional view of an embodiment of a water meter. 1... Measuring instrument, 2... Reading board, 3... Transmission line (cable), 4... Inductive coupling means, 6, 6'...
...Voltage source, 7, 10... Coil, 8, 9... Yoke, 11... Voltage detection means, 12... Switch.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In an electronic measuring instrument such as an electronic water meter, a yoke fixed to the measuring instrument and having a coil wound thereon, a voltage detecting means connected to the coil, and transmitting a measured value. In order to do this, a switch is provided that turns on and off according to the flow rate signal, while on the reading side there is provided a voltage source and inductive coupling means consisting of a coil connected to the end of the cable and wound around a yoke. A magnetically coupled remote reading device characterized in that the inductive coupling means is detachably attached to the measuring instrument so as to form a closed magnetic circuit with the yoke fixed to the measuring instrument. 2. The voltage detection means is comprised of a rectifier 11a that rectifies the voltage induced in the coil of the measuring instrument and a resistor 11b that receives the rectified voltage, and a switch is connected in parallel to this resistor 11b. 2. The magnetically coupled remote reading device according to item 1. 3. The magnetically coupled remote reading device according to claim 1, which is a utility model and is equipped with an oscillator 15 that uses a battery 6' as a voltage source on the reading side and converts direct current into alternating current and supplies the same to the inductive coupling means.