JPH0639308Y2 - Electromagnetic flow meter pseudo input device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a pseudo input device for an electromagnetic flow meter that measures the flow rate of a fluid flowing through piping or the like.

[Conventional technology]

Conventionally, as a pseudo input device of this kind of electromagnetic flow meter,
Some are shown in the figure.

In the figure, the exciting current output from the exciting circuit 2 in the converter 1 of the electromagnetic flow meter is input to the terminals X and Y of the pseudo input device 3. Then, the exciting current is input to the parallel circuit of the series circuit of the high resistances R1 to R4 and the low resistance R5, most of which flows through the resistance R5, but a part thereof flows into the series circuit of the resistances R1 to R4. The exciting current flowing through this series circuit is
The voltage is divided by R4, and the divided voltage is input as a pseudo signal to the amplifier 4 in the converter 1 via the terminals A, B, and C. This input signal is regarded as a detection voltage generated by the fluid flowing in the pipe to which the magnetic flux is applied, and is converted into a flow rate display signal by the signal processing circuit 5 to be output, so that the converter 1 operates normally. Used for confirmation of operation.

[Problems to be solved by the device]

However, in the above-described conventional pseudo input device, the exciting circuit 2 is adjusted to a predetermined value and then the converter 1 is adjusted.
Therefore, it is necessary to change the excitation current value once set according to the customer's specifications at the time of factory shipment to check the converter. For this reason, the process work involved in the inspection of the converter is increased, and forgetting the work of returning the excitation current value changed for checking after the inspection to the original setting value again, the electromagnetic flowmeter is shipped as it is and malfunctions. Had the problem of causing.

[Means for Solving the Problems]

The present invention has been made in order to solve such a problem, and a pseudo input device (3) of an electromagnetic flowmeter is replaced with a converter (1).
Input terminals (X, Y) for connecting to the output terminals of, low resistance (R6) with a relatively low resistance value connected between these input terminals, and parallel connection with this low resistance. A constant voltage generator circuit that has a high resistance (R7, R8, R9, R10) with a high resistance value and that generates a constant voltage in the high resistance regardless of the current value of the exciting current flowing in the low resistance. The output terminal (A, B, C) for connecting to the input terminal of the converter connected to the high resistance voltage output terminal of the generating circuit.

[Action]

The constant voltage generating circuit is supplied with power from the exciting circuit, and a constant pseudo signal that does not depend on the exciting current is output to the amplifier.

〔Example〕

 The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and the same parts as in FIG.

In the figure, the exciting current from the exciting circuit 2 is supplied to the low resistance R6, and a part of the exciting current is supplied to the constant current generating circuits CCS1 and CCS.
Supplied to 2. The constant current generating circuits CCS1 and CCS2 always output a constant current regardless of the value of the exciting current, and this output current is supplied to the series circuit of the resistors R7 to R10.

Therefore, the voltage generated by each resistor is always constant, and the amplifier 4 of the converter 1 via the terminals A, B, and C receives a constant pseudo signal regardless of the excitation current value of the excitation circuit 2. It

The diodes D1 and D2 constitute a return path in which the exciting current flows through the resistors R7 to R10 and then returns to the exciting circuit 2. Also,
Normally, the respective resistance values are set so that the resistance R7 = R10 and the resistance R8 = R9.

FIG. 2 is a circuit diagram showing another embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In the figure, constant voltage ICs 6 and 7 are provided in place of the constant current circuits CCS1 and CCS2 in FIG. 1, and the grounded common line is connected to the connection point between the resistors R8 and R9.

Also in this embodiment, a constant voltage is always supplied to the series circuit of the resistors R7 to R10 by the constant voltage circuits IC6, 7 regardless of the exciting current from the exciting circuit 2, so that the amplifier 4 of the converter 1 is supplied with the constant voltage. The input pseudo input signal is always constant regardless of the exciting current of the exciting circuit 2.

FIG. 3 is a circuit diagram showing another embodiment of the present invention. The same parts as those in FIG.

In the figure, instead of the constant current circuits CCS1 and CCS2 in FIG. 1, transistors Tr1 and Tr2, resistors R11 and R12, zener diodes ZD1 and ZD2, and diodes D3 and D4 are connected as shown.

The exciting current from the exciting circuit 2 corresponds to each current direction,
The resistor R11 and the zener diode ZD1 are input to each series circuit of the resistor R12 and the zener diode ZD2, and a constant voltage determined by the breakdown voltage characteristic of each zener diode ZD1,2 is applied to the base of each transistor Tr1,2. Therefore, the transistors Tr1 and Tr2 always amplify the exciting current with a constant amplification degree and always supply a constant current to the series circuit of the resistors R7 to R8. The diodes D3 and 4 prevent the current flowing from the connection point of the resistors R8 and R9 from flowing in the forward direction of the zener diodes ZD1 and ZD2.

As described above, also in this embodiment, a constant pseudo signal is always supplied to the amplifier 4 regardless of the exciting current from the exciting circuit 2.

[Effect of device]

As described above, the present invention provides a pseudo signal which is connected to the exciting circuit of the electromagnetic flowmeter and is connected in parallel to this low resistance regardless of the exciting current value of the exciting current and at the same timing as this exciting current. Since the constant voltage generating circuit is provided with a high resistance constant voltage generating circuit for transmitting the power, the constant voltage generating circuit is supplied with power from the exciting circuit, and a constant pseudo signal that does not depend on the exciting current is output to the amplifier.

Therefore, there is an effect that the step of changing the setting of the exciting current value once set at the time of factory shipment for the inspection of the converter and the steps associated therewith are omitted, and the check is performed after the inspection of the converter. There is an effect that the problem of forgetting the operation of returning the exciting current value changed for the setting to the original setting value again and causing the electromagnetic flow meter to be shipped as it is to cause a malfunction is solved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment in which the present invention is realized by using a constant current circuit CCS, and FIG. 2 shows another embodiment in which the present invention is realized by using a constant voltage IC. Circuit diagram, third
FIG. 4 is a circuit diagram showing another embodiment in which the present invention is realized by using a transistor and a zener diode, and FIG. 4 is a conventional circuit diagram. 1 ... Converter, 2 ... Excitation circuit, 3 ... Pseudo input device,
4 ... Amplifier, 5 ... Signal processing circuit, CCS1, CCS2 ... Constant current generation circuit, D1, D2 ... Diode, R6 ... Low resistance, R
7-R10 …… High resistance.

Claims (1)

[Scope of utility model registration request] 1. An electromagnetic flow meter for measuring a flow rate of a fluid by applying a magnetic flux generated by exciting the coil to the fluid, detecting and amplifying a voltage generated by the flow of the fluid, and supplying the same to the coil. An exciting circuit for generating an exciting current, an output terminal for outputting the exciting current, an input terminal for inputting the detection voltage, an amplifier for amplifying the voltage input to the input terminal, and an amplified output of the amplifier. A pseudo input device for inputting a pseudo signal by connecting to a converter of an electromagnetic flowmeter having a signal processing circuit for converting the signal into a flow signal, the pseudo input device being connected to an output terminal of the converter. For input, a low resistance with a relatively low resistance value connected between the input terminals, and a high resistance with a relatively high resistance value connected in parallel with this low resistance, Exciting current flowing Constant voltage generating circuit for generating a constant voltage in a high resistance irrespective of the current value of, and connected to the input terminal of the converter, which is connected to the high resistance voltage output terminal of the constant voltage generating circuit. An electromagnetic flowmeter pseudo-input device characterized by being configured with an output terminal.