JPS593368A - Detector for abnormality in resistance bridge circuit - Google Patents

Abstract

PURPOSE:To detect exactly the abnormal state such as disconnection in a resistance bridge circuit, by executing the detection at intervals of a specified period in the program for discriminating overload which is normally executed to detect whether the potentials at a pair of arm junctions are within a prescribed permissible range or not. CONSTITUTION:The output terminal of an exciting power source 2 is connected between a pair of mutually opposed arm junctions 11 and 12 of a resistance bridge circuit 1, and a square wave signal is applied thereto in accordance with the latched output from a microprocessor 3. The (a), (b) contacts of a signal reception circuit 4 constituted of an analog switch are connected to a pair of the other arm junctions 13, 14 of the circuit 1, and are pulled up by a resistance 9. The output potential is taken into the circuit 4 by the command signal of the microprocessor 3 and is taken into the microprocessor 3 through an A/D converter 5. The decision of abnormality is accomplished at a specified interval in the program, and the abnormality is discriminated by the comparison of the permissible upper and lower limit values stored in a data ROM32.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that accurately detects abnormal conditions such as disconnection of a resistor bridge circuit.

Resistance bridge circuit wires are widely used as stress detectors, and are also used as moment detectors by being attached to the rods of boom hoisting cylinders of crane vehicles, aerial work vehicles, etc. If an abnormality such as a disconnection or the like occurs in such a resistor circuit, it is difficult to accurately detect the load, so a device that constantly monitors the presence or absence of such an abnormality is desired. The present invention was devised in view of the above circumstances and provides a complete installation that can quickly and accurately detect abnormalities.

The present invention will be explained below based on examples. Fig. 1 is a block diagram of this embodiment, where 1 is the moment acting on the boom of a crane vehicle, aerial work vehicle, etc.) 1 - A resistor bridge circuit for detecting 0 The relative of the resistor bridge circuit 1 An output terminal of an excitation power source 2 is connected between a pair of arm connection points 11% and 12 facing each other, and this excitation power source 2 applies a rectangular wave signal based on the latch output of the microprocessor 3. There is. The other pair of opposing arm connection points 13 and 14 of the resistor bridge circuit 1 are connected to the a contact and the b contact of the receiving circuit 4 constituted by an analog switch. + is added. Note that this pull-up voltage is set to exceed the allowable upper limit value of abnormality determination reference data, which will be described later. The receiving circuit 4 is configured to switch to receive the output potential from the connection point a and the connection point b in response to a command signal from the microprocessor 3, and to transmit the signal to the connected A/D converter 5. It has become. The digitally converted output potential is then taken into the microprocessor 3 via the gate 35. Reference numeral 3 denotes a microprocessor of known construction, which functions as a monitoring device in the embodiment of the present invention. That is, it compares the output potential taken in according to the judgment program built in the program ROM 31 with the abnormality judgment reference data built in the data ROM, performs all comparison judgments, and issues the output command to the latch 36 and the receiving circuit 4 necessary for its execution. Address decoder that decodes various commands of the a PU 30 and outputs them as control signals to auxiliary equipment such as latches and gates. 341 data is temporarily stored R
It is composed of AM33 etc. Reference numeral 6 denotes an alarm device such as a lamp or a buzzer used to notify of a disconnection or the like occurring in the resistor bridge circuit 1. In this figure, arm connection point 13.
14 is connected to the next amplifier 7. The sample and hold circuit 8 is provided in order to amplify the detected potential when the resistor bridge circuit 1 acts as a normal moment detection time and hold the sample in accordance with the processing of the receiving circuit 4.
In the normal state, the microprocessor 3 also functions as an overload determining device.Now, in the embodiment of the present invention having such a configuration, the entire abnormality determining process will be explained based on the flowchart of FIG. 2. The abnormality determination program shown in the illustrated flowchart is continuously executed at regular intervals in the normally executed overload determination program, and when this program starts, abnormality determination is performed in the following order.

First, the 0PU 30 issues a rectangular wave rise command to all latches 36 to cause the excitation power source 2 to output a rectangular wave signal.

Next, after a time lag for the rectangular wave to become stable, a contact a connection command is issued to the receiving circuit 4, and a gate opening command is issued to the gate 35. As a result, the output potential of the arm connection point 13 is a of the receiving circuit 4.
The signal enters the A/D converter 5 from the contact, is converted into a digital value, and is temporarily stored in the RAM 33 via the gate 35. Similarly, when a b contact connection command is issued, the output potential of the arm connection point 14 is input from the b contact of the receiving circuit 4 to the A/D converter 5.
．． The data is stored in the RAM 33 via the gate 35. Next, 0PU30 receives the output potential ■,
A determination step is entered in which the data ROM 32 is completely compared with the permissible upper limit value and permissible lower limit value stored in the data ROM 32. Here, the allowable upper limit value and allowable lower limit value should be set based on the appropriate range of output potential when the resistor bridge circuit 1 is normal, and if these upper/lower limit values are exceeded, it may be determined as abnormal. It becomes.

Now, what are the output potentials Va and Vb of the resistor bridge circuit 1?

If a disconnection occurs in the applied voltage connection path, both potentials become zero, which means that the potential is below the allowable lower limit. In addition, if a break occurs in the ground side connection path, the applied voltage will be equal to the allowable upper limit value. Furthermore, if a disconnection occurs in the output line, a pull-up voltage is applied, which also exceeds the allowable upper limit value. On the other hand, if all the lines of the resistor bridge circuit 1 are normal, the output voltage will be 172 of the applied voltage, so it should fall within the above-mentioned allowable upper/lower limits. If the upper and lower limit values are matched and it is determined whether it is within the frame or outside the frame, the presence or absence of wire breakage can be completely detected.

This is the result of executing all the determination steps in this way.

If it is determined that there is an abnormality, the 0PU 30 issues an alarm command to the latch 37, executes the nine abnormality routines such as displaying the abnormal location, and returns to the initial position. If it is determined to be normal, the 0PU30 issues a rectangular wave signal fall command to the latch 36 in accordance with the rectangular wave period timing, and thereafter returns to execution of the load determination program in order to emit all the drive signals at the time of moment detection. .

When the alarm command is issued, the latch output 37 is given and the alarm 6 is activated, so that the occurrence of wire breakage can be accurately detected. Furthermore, if the abnormality routine is executed, the location of the disconnection is displayed on an appropriate display, which facilitates subsequent repairs.

However, the present invention is practically useful because it can accurately detect abnormalities such as disconnections in resistor bridge circuits in the same way as vaporization.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a flowchart showing an abnormality determination program of the apparatus of the present invention. 1: Resistance bridge circuit 2: Excitation power source 3: Monitoring device 4: Receiving circuit 5: A/D converter 6: Alarm device procedure amendment (method) November 1939 4-[1 Commissioner of the Japan Patent Office 1. Matters Display of f'l Patent application 1987-//'l! ;/
No. 7 No. 2, Title of the invention Abnormality detection W of resistor bridge circuit; 3. Relationship with small name f1 to be amended Patent Applicant I1 Location Kagawa +1! If, Matsu City Shin 111-cho Ko 3
Address 4 fj Name 5 Date of amendment order Showa JFY 19 September 9
11 (Showa Tough Q Wa month, 2g [J shipping) and 1st invention of 1st line of Ω] shall be amended to F present invention J. Description ■1 Name of the invention An abnormality detection device for a resistor bridge circuit 2, Claims (11) An excitation device connected to apply a rectangular wave signal between a pair of opposing arm connection points of a resistor bridge circuit (1) A power source (2), a monitoring device (
3), wherein the monitoring device (3) determines whether the output potential taken in from the receiving circuit (4) is within a predetermined tolerance range. . (2) The monitoring device (3) consists of a microprocessor;
An abnormality in a resistor bridge circuit according to claim 1, characterized in that it is determined based on a determination program whether the output potential of the resistor bridge circuit (1) exceeds a permissible upper limit value and a permissible lower limit value. Detection device. 3. Detailed Description of the Invention The present invention relates to a device that accurately detects abnormal conditions such as disconnection of a resistor bridge circuit. Resistance bridge circuits are widely used as stress detectors, and are also used as moment detectors by being attached to the rond of the boom hoisting cylinders of crane vehicles, aerial work vehicles, etc. If an abnormality such as a disconnection occurs in such a resistor bridge circuit, it is difficult to accurately detect the load, so a device that constantly monitors the presence or absence of such an abnormality is desired. The present invention was devised in view of such circumstances, and provides a device capable of quickly and accurately detecting abnormalities. The present invention will be explained below based on examples. FIG. 1 is a block diagram of this embodiment, and symbol (2) is a resistance bridge circuit for detecting the moment acting on the boom of a crane vehicle, aerial work vehicle, etc. An output terminal of an excitation power supply 2 is connected between a pair of opposing arm connection points 11 and 12 of the resistor bridge circuit 1, and this excitation power supply 2 generates a rectangular wave signal based on the launch output from the microprocessor 3. Mark 1k17 Returns to execution of the load determination program. When the alarm command is issued, the latch output 37 is given and the alarm 6 is activated, so that the occurrence of wire breakage can be accurately detected. Furthermore, by executing the abnormality routine, displaying the location of the disconnection on an appropriate display can facilitate subsequent repairs. In summary, the present invention is industrially useful because it can accurately detect abnormalities such as disconnections in resistor bridge circuits using vapor deposition methods. 4. Brief Description of the Drawings FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2 is a flowchart showing an abnormality determination program of the apparatus of the present invention. l: Resistance bridge circuit 2: Excitation power supply 3: Monitoring device 4: Receiving circuit 5: A/D converter 6: Alarm device 345

Claims (2)

[Claims] (1) An excitation power supply (2) connected to apply a square wave signal between a pair of opposing arm connection points of the resistance bridge circuit (1), and another pair of arm connection points of the resistance bridge circuit (1). A monitoring device (
3) Karanashi. An abnormality detection device for a resistor bridge circuit, characterized in that the monitoring device (3) determines whether the output potential received from the receiving circuit (4) is within a predetermined tolerance range. (2) The monitoring device (3) is a system 1 based on a microprocessor.
A resistor bridge circuit according to claim 1 of the utility model registration claim, which is characterized in that it determines whether the output potential of the resistor bridge circuit (1) exceeds an upper limit value and a lower limit value based on a determination program. abnormality detection device