Input contact diagnosis device

Abstract

To provide a contact diagnostic device whereby, before a failure of a contact, deterioration of the contact can be diagnosed with a simple configuration.SOLUTION: A contact diagnostic device includes: an inspection circuit 20 including a contact 1 to be diagnosed, a contact power supply 21, a load capacitor 2, and a switching element 4 connecting the contact 1 and the contact power supply 21; an input state determination element 5 configured to output an input signal that is High when a voltage applied to the contact 1 is equal to or higher than a predetermined threshold and is Low when the voltage applied to the contact is lower than the predetermined threshold; and a diagnosis unit 22 configured to drive the switching element 4 to switch a connection state between the contact 1 and a contact power supply 21 and diagnose deterioration of the contact 1, based on a change rate of the input signal associated with the switching of the connection state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification discloses an input contact diagnosis device for diagnosing deterioration of contacts.

Background Art

[0002] The input contacts used in a sequencer or the like may gradually deteriorate due to ON / OFF operations and suddenly stop functioning.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the input contacts used in a sequencer or the like, when deterioration progresses and the contacts suddenly stop functioning, a situation occurs where the machine cannot be operated until the repair is completed.

[0005] In the method and apparatus for diagnosing deterioration of electrical contacts disclosed in Patent Document 1, the deterioration of the input contacts is determined by the contact resistance of the contacts. However, since Patent Document 1 directly measures the resistance value of the contacts, cost and component mounting area are issues for practical implementation.

[0006] Also, in the technique disclosed in Patent Document 2, a predetermined diagnostic pulse is used to diagnose whether the contacts are operating normally. However, in Patent Document 2, deterioration of the contacts cannot be detected before the contacts fail.

[0007] Therefore, this specification discloses a contact diagnosis device that can diagnose deterioration of the contacts with a simple configuration before the contacts fail.

Means for Solving the Problems

[0008] The input contact diagnosis device disclosed in this specification Connection includes a point power source, a load capacitance, Located between the contact power supply and the load capacity an inspection circuit including a contact to be diagnosed and a switching element that connects the contact and the contact power source, an input state determination element that outputs an input signal that becomes High when the voltage applied to the contact is equal to or higher than a specified threshold value and becomes Low when the voltage is lower than the threshold value, and a diagnosis unit that drives the switching element to switch the connection state between the contact and the contact power source and diagnoses the deterioration of the contact based on the change rate of the input signal accompanying the switching of the connection state. For diagnosing the contact, the diagnosis unit cuts off the connection between the contact and the contact power supply with the contact closed, and after the input signal switches to Low and a specified reference OFF time has elapsed, resumes the connection. When the return time, which is the time from when the connection is resumed until the input signal switches to High, is equal to or greater than a specified comparison value, it is determined that deterioration due to an increase in the contact resistance of the contact has occurred. It is characterized by this.

[0011] In this case, the diagnosis unit performs a process of disconnecting the connection between the contact and the contact power source in a normal state of the contact and then reopening the connection after a predetermined standby time has elapsed, while gradually increasing the standby time, Process of resuming the connection and repeats the process until the return time from the time when the input signal becomes High is the same as the previous return time. Process of resuming the connection When the return time from the time when the input signal becomes High is the same as the previous return time, a value larger than the return time at that time is set as the comparison value, and a value larger than the standby time at that time when the return time is the same as the previous return time may be set as the reference OFF time.

[0012] Also, The input contact diagnosis device includes an inspection circuit including a contact power supply, a load capacity, a contact to be diagnosed located between the contact power supply and the load capacity, and a switching element that connects the contact and the contact power supply, and an input state determination element that outputs an input signal that becomes High when the voltage applied to the contact is equal to or greater than a specified threshold value and becomes Low when it is less than the threshold value. The diagnosis unit drives the switching element to switch the connection state between the contact and the contact power supply, and diagnoses the deterioration of the contact based on the change rate of the input signal accompanying the switching of the connection state. For diagnosing the contact, the diagnosis unit cuts off the connection between the contact and the contact power supply with the contact closed, and after the input signal switches to Low and a specified reference OFF time has elapsed, resumes the connection. when the time from the timing when the input signal switches to Low until the input signal switches to High is equal to or longer than a specified comparison value Deterioration due to an increase in the contact resistance of the contact has occurred it is determined that Do.

[0013] Also, The input contact diagnosis device includes an inspection circuit including a contact power supply, a load capacity, a contact to be diagnosed located between the contact power supply and the load capacity, and a switching element that connects the contact and the contact power supply, and an input state determination element that outputs an input signal that becomes High when the voltage applied to the contact is equal to or greater than a specified threshold value and becomes Low when it is less than the threshold value, and a diagnosis unit that drives the switching element to switch the connection state between the contact and the contact power supply, and diagnoses the deterioration of the contact based on the change rate of the input signal accompanying the switching of the connection state. For diagnosing the contact, the diagnosis unit cuts off the connection between the contact and the contact power supply with the contact closed, and after the input signal switches to Low and a specified reference OFF time has elapsed, resumes the connection. when the time from when the connection is disconnected until the input signal switches to High is equal to or longer than a specified comparison value Deterioration due to an increase in the contact resistance of the contact has occurred it is determined that Do.

Advantages of the Invention

[0014] According to the technology disclosed in this specification, it becomes possible to grasp the deterioration status of the contact at low cost. As a result, it becomes possible to plan the maintenance of the machine before the contact fails, and it is possible to prevent the unexpected stop of the machine.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0016] Hereinafter, an embodiment of the input contact diagnosis device will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the input contact diagnosis device. The input contact diagnosis device includes an inspection circuit 20, an input state determination element 5, and a diagnosis unit 22. The inspection circuit 20 includes a contact 1 to be diagnosed, a contact power supply 21, a load capacitance 2, and a switching element 4. The contact 1 is connected to the input state determination element 5 through a filter circuit 3. Note that the contact resistance 1a is the contact resistance existing in the contact 1, and the load capacitance 2 exists on the wiring. The input state determination element 5 compares the voltage level of an electrical signal (hereinafter referred to as the "inspection signal") output from the filter circuit 3 with a predetermined threshold value. Note that the filter circuit 3 is a low-pass filter provided for the purpose of noise removal, and the voltage level of the inspection signal can be regarded as the voltage applied to the contact 1, that is, the contact voltage. If the level of the inspection signal is equal to or higher than the threshold value, the input state determination element 5 outputs a High signal, and if the level of the inspection signal is lower than the threshold value, the input state determination element 5 outputs a Low signal. Hereinafter, the High or Low signal output from the input state determination element 5 will be referred to as the "input signal".

[0017] The contact power supply 21 connected to the contact 1 is controlled by the switching element 4. A check signal generated by a check signal generation unit 6, which will be described later, is input to the control input of the switching element 4. During the period when the check signal is input, the switching element 4 turns OFF, and the connection between the contact 1 and the contact power supply 21 is interrupted.

[0018] The output of the input state determination element 5 is input to the input signal monitoring unit 12. When the input signal is Low, the input signal monitoring unit 12 outputs an input OFF confirmation signal, and when the output signal is High, the input signal monitoring unit 12 outputs an input ON confirmation signal. The input OFF confirmation signal is input to the OFF time counter 13. The OFF time counter 13 counts the duration during which the input signal is OFF (Low) as the "OFF time". Further, the OFF time counter 13 compares the current OFF time with the reference OFF time input from the OFF time storage unit 10. The reference OFF time is the time for temporarily turning off the switching element 4 for the inspection of the contact 1. Such reference OFF time is a fixed value determined in advance by experiments. The procedure for determining this reference OFF time will be described later. As a result of the comparison, if the current OFF time reaches the reference OFF time, the OFF time counter 13 outputs a check signal OFF request to the check signal generation unit 6. When receiving this check signal OFF request, the check signal generation unit 6 stops the output of the check signal to the switching element 4. Thereby, the switching element 4 turns ON, and the contact 1 and the contact power supply 21 are connected again.

[0019] The input ON confirmation signal is input to the return time counter 7 and the determination unit 8. The return time counter 7 counts the time from when the switching element 4 switches from OFF to ON until the input signal becomes ON (High) as the "return time". For this counting, the return time counter 7 receives the check signal output from the check signal generation unit 6 and the input ON confirmation signal output from the input signal monitoring unit 12.

[0020] The determination unit 8 determines the state of contact 1 based on the return time output from the return time counter 7. Specifically, the determination unit 8 compares the return time with a specified comparison value. If the return time is greater than the comparison value, it is determined that an abnormality has occurred in contact 1, and a warning is output. The comparison value is a fixed value obtained in advance through experiments and stored in the comparison value storage unit 9. The procedure for determining this comparison value will also be described later. The display 11 outputs text, images, sounds, etc. corresponding to the warning to prompt the operator.

[0021] The above-described check signal generation unit 6, return time counter 7, determination unit 8, comparison value storage unit 9, OFF time storage unit 10, input signal monitoring unit 12, and OFF time counter 13 constitute the diagnosis unit 22. This diagnosis unit 22 may be composed of an FPGA (field-programmable gate array) or a computer having a processor and a memory.

[0022] Next, the principle of diagnosing the contact in this input contact diagnostic device will be briefly explained. When contact 1 deteriorates, the resistance value of the contact resistance 1a increases, and the change in the contact voltage accompanying the ON / OFF of the contact power supply 21 becomes gentle. In this example, this characteristic is utilized to diagnose the deterioration of contact 1. Specifically, a check signal is output to turn off the switching element 4. This OFF state is continued for a specified reference OFF time. Accordingly, the contact voltage decreases and the input signal switches to OFF. If the contact voltage has sufficiently decreased, the output of the check signal is stopped and the switching element 4 is turned on. Accordingly, the contact voltage increases and the input signal switches to ON. When contact 1 is deteriorated, the time (hereinafter referred to as the "return time") from when the switching element 4 is switched to ON until the input signal is switched to ON becomes longer. Therefore, in this example, if this return time is equal to or greater than the specified comparison value, it is determined that the contact is deteriorated and a warning is output. The "reference OFF time" and the "comparison value" are obtained in advance through experiments as described above.

[0023] Next, the flow of the process for determining the comparison value and the reference OFF time will be described. FIG. 2 is a flowchart showing the operations for determining the comparison value stored in the comparison value storage unit 9 and the reference OFF time stored in the OFF time storage unit 10.

[0024] In step S1, the initial values of the OFF time storage unit 10 and the comparison value storage unit 9 are set. In the case of this example, the initial value of the comparison value is "0", and the initial value of the reference OFF time is "1". Subsequently, in step S2, the check signal is turned ON. In step S3, if the input signal becomes Low, the process proceeds to step S4. In step S4, the OFF time counter 13 is started. In step S5, it is confirmed whether the count value of the OFF time counter 13 has reached the reference OFF time stored in the OFF time storage unit 10. If the count value becomes equal to or greater than the reference OFF time, the process proceeds to step S6.

[0025] If the count value reaches the reference OFF time, after stopping the OFF time counter 13, 1 is added to the value of the reference OFF time stored in the OFF time storage unit 10, and the count value of the OFF time counter 13 is cleared. Also, if the count value reaches the reference OFF time, the check signal is turned OFF (S7).

[0026] If the count value reaches the reference OFF time, further, the return time counter 7 is started (S8). If the input signal is switched to High (S9), the process proceeds to step S10. If the count value of the return time counter 7 (i.e., the return time) is less than or equal to the comparison value stored in the comparison value storage unit 9, the process proceeds to step S12, and if the return time is greater than the comparison value, the process proceeds to step S11.

[0027] When the return time is greater than the comparison value, the return time counter 7 is stopped (S11). Also, after storing the count value of the return time counter 7 (i.e., the return time) in the comparison value storage unit 9 as a new comparison value, the count value of the return time counter 7 is cleared, and the process proceeds to step S2. When the return time is greater than or equal to the comparison value, a value obtained by adding margin A to the current comparison value is determined as the formal comparison value, and a value obtained by adding margin B to the current reference OFF time is determined as the formal reference OFF time (S12).

[0028] Next, with reference to FIG. 3, the method for determining the reference OFF time and the comparison value will be described. When determining the reference OFF time and the comparison value, first, the initial values of the reference OFF time and the comparison value are set. In this example, the initial value of the reference OFF time is 1, and the initial value of the comparison value is 0.

[0029] In this state, the check signal generation unit 6 sets the check signal to the high level and cuts off the connection between the contact 1 and the contact power supply 21 (t5). According to the characteristics of the inspection circuit 20, the voltage of the inspection signal (i.e., the contact voltage) begins to gradually drop. When the voltage level of the inspection signal falls below the threshold value of the input state determination element 5, the input signal becomes Low (t7). When the input signal switches to Low, the input signal monitoring unit 12 outputs an input OFF confirmation signal to the OFF time counter 13.

[0030] After the OFF time counter 13 receives the input OFF confirmation signal and after the reference OFF time stored in the OFF time storage unit 10 has elapsed, the OFF time counter 13 outputs a check signal OFF request to the check signal generation unit 6. Since the reference OFF time at timing t7 is the initial value "1", the check signal OFF request is output at timing t8, which is "1" elapsed from timing t7.

[0031] The check signal generation unit 6 that has received the check signal OFF request sets the check signal to the low level and resumes power supply to the contact 1. Also, the return time counter 7 starts counting (t8). At this time, 1 is added to the reference OFF time.

[0032] After the power supply is restarted after timing t8, according to the characteristics of the inspection circuit 20, the voltage level of the inspection signal starts to gradually increase. When this voltage exceeds the threshold value of the input state determination element 5, the input signal switches to High (t9). In this case, the input signal monitoring unit 12 outputs an input ON confirmation signal to the return time counter 7.

[0033] Upon receiving the input ON confirmation signal, the return time counter 7 stops counting, and the determination unit 8 compares the current comparison value (which is "0" at this time) with the count value (return time, which is "1" at this time) output by the return time counter 7.

[0034] In the case of the embodiment, since the count value (return time) is greater than the current comparison value, the process proceeds to step S11 in FIG. 2. That is, the return time at timing t9 (which is "1" in the example) is set as the new comparison value. Also, the return time counter 7 is cleared after stopping.

[0035] When this operation is repeated several times, the reference OFF time gradually becomes longer. Also, in the case of this example, at timing t32 when the above process has been performed three times, the count value (return time) becomes less than or equal to the comparison value. When the count value (return time) becomes less than or equal to the comparison value, in the comparison value storage unit 9, the value obtained by adding margin A (which is 1 in this embodiment) to the current comparison value is stored as the formal comparison value. Also, at this time, in the OFF time storage unit 10, the value obtained by adding margin B (which is 0 in this embodiment) to the current reference OFF time is stored as the formal reference OFF time.

[0036] As is clear from the above description, in this example, after the switching element 4 is turned OFF and the input signal switches to Low, the process of turning on the switching element 4 after a predetermined reference OFF time has elapsed is repeated while gradually increasing the reference OFF time. Then, when the return time measured at that time becomes the same as the previous return time, the reference OFF time at that point is determined as the formal reference OFF time, and a value greater than or equal to the return time at that point is determined as the formal comparison value.

[0037] Next, the operations in the initial state and when deterioration has progressed will be described with reference to FIG. 4. In the initial state, since the return time measured by the return time counter 7 is smaller than the preset comparison value, the warning will not turn on.

[0038] However, deterioration of the contact due to contact operation or the like increases the resistance value of the contact resistance 1a, and the change in the input voltage of the input state determination element 5 accompanying the ON / OFF of the contact power supply 21 becomes gradual. As this state progresses, the time taken for the voltage change associated with power supply voltage cut-off and return becomes longer, and the return time increases.

[0039] When this return time becomes equal to or greater than the preset comparison value, the warning will turn on. For example, in the case of FIG. 4, the return time at timing t35 is "3", and since the comparison value is "3", the warning turns on. When the warning turns on, the display 11 displays the content to inform the operator of the need for maintenance.

[0040] Next, another example will be described. In the example described above, the time from when the switching element 4 is turned on until the input signal becomes High is counted as the "return time". However, as long as the "return time" reflects the change rate of the contact voltage, the time at other timings may also be used. For example, as shown in FIG. 5, the time from when the input signal switches to Low until it switches to High may be counted as the "return time". In this case, the comparison value is the value obtained by adding the reference OFF time to the comparison value obtained by the procedure of FIG. 2. As another example, as shown in FIG. 6, the time from when the switching element 4 is turned off until the input signal switches to High may be counted as the "return time". In both cases of FIGS. 5 and 6, the return time tends to increase as the contact 1 deteriorates, so it is possible to diagnose the deterioration of the contact 1 in the same way as in the case of FIG. 4.

Explanation of Reference Numerals

[0041] 1 Contact, 1a Contact Resistance, 2 Load Capacity, 3 Filter Circuit, 4 Switching Element, 5 Input State Determination Element, 6 Check Signal Generation Section, 7 Recovery Time Counter, 8 Determination Section, 9 Comparison Value Storage Section, 10 OFF Time Storage Section, 11 Display, 12 Input Signal Monitoring Section, 13 OFF Time Counter, 20 Inspection Circuit, 21 Contact Power Supply, 22 Diagnosis Section.

Claims

1. An inspection circuit including a contact power supply, a load capacitance, a contact to be diagnosed located between the contact power supply and the load capacitance, and a switching element connecting the contact and the contact power supply; An input state determination element that outputs an input signal which becomes High when the voltage applied to the contact is equal to or higher than a specified threshold value and becomes Low when it is less than the threshold value; A diagnosis unit that drives the switching element to switch the connection state between the contact and the contact power supply, and diagnoses the deterioration of the contact based on the change rate of the input signal accompanying the switching of the connection state; Comprising: The diagnosis unit: For diagnosing the contact, with the contact closed, after cutting off the connection between the contact and the contact power supply, after the input signal switches to Low and a specified reference OFF time has elapsed, resume the connection; When the recovery time, which is the time from resuming the connection until the input signal switches to High, is equal to or longer than a specified comparison value, it is determined that deterioration due to an increase in the contact resistance of the contact has occurred. A contact diagnosis device characterized by the above.

2. The contact diagnosis device according to Claim 1, The diagnosis unit performs a process of cutting off the connection between the contact and the contact power supply in a normal state of the contact, and after a predetermined standby time has elapsed, resumes the connection, while gradually increasing the standby time, and repeats the process until the recovery time from resuming the connection until the input signal becomes High becomes the same as the previous recovery time; Set a value larger than the recovery time at the time when the recovery time from resuming the connection until the input signal becomes High becomes the same as the previous recovery time as the comparison value; Set a value larger than the standby time at the time when the recovery time becomes the same as the previous recovery time as the reference OFF time. A contact diagnosis device characterized by the above.

3. An inspection circuit including a contact power supply, a load capacitance, a contact to be diagnosed located between the contact power supply and the load capacitance, and a switching element connecting the contact and the contact power supply; An input state determination element that outputs an input signal which becomes High when the voltage applied to the contact is equal to or higher than a specified threshold value and becomes Low when it is less than the threshold value; A diagnosis unit that drives the switching element to switch the connection state between the contact and the contact power supply, and diagnoses the deterioration of the contact based on the change rate of the input signal accompanying the switching of the connection state; Comprising: The diagnostic unit: For diagnosing the contact, with the contact in a closed state, after cutting off the connection between the contact and the contact power supply, after the input signal switches to Low and a specified reference OFF time has elapsed, resume the connection; From the timing when the input signal switches to Low, if the time until the input signal switches to High is equal to or greater than a specified comparison value, determine that deterioration due to an increase in the contact resistance of the contact has occurred; A contact diagnostic device characterized by the above.

4. An inspection circuit including a contact power supply, a load capacitance, a contact to be diagnosed located between the contact power supply and the load capacitance, and a switching element connecting the contact and the contact power supply; An input state determination element that outputs an input signal that becomes High when the voltage applied to the contact is equal to or greater than a specified threshold value and becomes Low when it is less than the threshold value; A diagnostic unit that drives the switching element to switch the connection state between the contact and the contact power supply, and diagnoses the deterioration of the contact based on the change rate of the input signal accompanying the switching of the connection state; Comprising: The diagnostic unit: For diagnosing the contact, with the contact in a closed state, after cutting off the connection between the contact and the contact power supply, after the input signal switches to Low and a specified reference OFF time has elapsed, resume the connection; The diagnostic unit determines that deterioration due to an increase in the contact resistance of the contact has occurred if the time from when the connection is cut off until the input signal switches to High is equal to or greater than a specified comparison value; A contact diagnostic device characterized by the above.

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