JP2795152B2 - DC electromagnetic brake abnormality detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of a DC electromagnetic brake mainly used for an overhead traveling crane or the like.

[0002]

2. Description of the Related Art For example, a DC electromagnetic brake used for an overhead traveling crane has a structure shown in FIGS. That is, brake arms 2B, 2B and 2A, 2A are arranged on the left and right sides of the brake table 1, and brake shoes 4, 4 for holding linings 3, 3 which are in sliding contact with the outer peripheral surface of the brake drum D are attached thereto. .

The bottoms of the brake arms 2A and 2B are pivotally supported on the brake table 1 by pins 5A and 5B.
A structure is provided in which the same distance is simultaneously approached and separated in the left and right directions with A and 5B as the centers. To make this contact,
The brake rods 6A and 6B are connected. Specifically, a connecting block 7 is integrated with an end of the brake rod 6A by screwing, and a spring receiver 8A is integrated with the connecting block 7. On the other hand, the brake rod 6B passes through the spring receiver 8B with play and passes through the inside of the brake spring 9 to be integrated with the spring receiver 8A. As shown in FIG. 1, a pair of spring force adjusting support rods 10, 10 are disposed in the horizontal direction, and the right ends of the support rods 10, 10 correspond to the brake arms 2B, 2B.
1 are supported by support shafts 12 and 12 erected between them. The left ends of the spring force adjusting support rods 10 and 10 are provided on both sides of the spring receiver 8B with the brake spring adjusting nuts 13 and 1 respectively.
3 and a corresponding lock nut.
Further, a braking spring 9 is interposed between the spring receiver 8A and the spring receiver 8B.

The left end of the brake rod 6B is fixed to the brake arm 2B by adjusting nuts 14,14. Reference numeral 15 denotes a manual loosening nut. An electromagnetic coil 16 is fixed to the upper right side of the brake arm 2A, and a brake rod 6A is inserted through the electromagnetic coil 16. A movable core 17 is fixed to an end of the brake rod 6A, and faces the electromagnetic coil 16 so as to be in contact with or separated therefrom.

In such an electromagnetic brake, when the electromagnetic coil 16 is energized during traveling of the overhead traveling crane, the movable core 17 is attracted to the electromagnetic coil 16. As a result, relatively, the electromagnetic coil 16 moves the movable core 17 sideways, and tilts the brake arm 2A clockwise about the pin 5A. This tilt limit is regulated by the tip of the clearance adjusting bolt 18. Further, when the movable core 17 is attracted by the electromagnetic coil 16, the brake rod 6A moves leftward so as to be compressed against the repulsive force of the brake spring 9, and as a result, the brake rod 6B and the brake arm 2B also move. Move to the left. As a result, the brake arm 2B tilts counterclockwise about the pin 5B. As a result, the linings 3, 3 and the brake shoes 4, 4 are separated from the outer peripheral surface of the brake drum D, so that the brake is released and the overhead traveling crane can travel.

On the other hand, when energization is stopped, the electromagnetic coil 1
6 is eliminated, and the movable core 17 is
, The braking spring 9 to which the compressive force has been applied is released, and the brake spring 6 is restored to the initial state, the brake rod 6A moves to the right, and then the left brake arm 2B
At the same time, the right brake arm 2A also falls to the left, and the linings 3, 3 slidably contact the outer peripheral surface of the brake drum D via the brake shoes 4, 4, and the illustrated brake operation state is established.

As a method for detecting the occurrence of an abnormality in this type of electromagnetic brake, a method disclosed in Japanese Patent Application Laid-Open Nos.
No. 63-290935 is disclosed. Japanese Patent Application Laid-Open No. 58-100086 discloses that the time required from the actuation of a brake on a drive motor to the stop of the drive motor or the number of revolutions of the drive shaft of the drive motor during that time is measured. This is a method of detecting an abnormality of the brake by comparing with the value of.

On the other hand, Japanese Patent Application Laid-Open No. 63-290935 discloses a method in which a strain gauge is attached to a tie rod of a brake to detect a control torque abnormality and a contact of a brake shoe from a strain signal at the time of brake operation.

[0009]

The main abnormality that occurs in the electromagnetic brake is that the distance between the electromagnetic coil 16 and the movable core 17 is too large due to the wear of the brake shoes or due to an adjustment error (hereinafter referred to as gap abnormality). Foreign matter is caught between the electromagnetic coil 16 and the movable core 17 (hereinafter referred to as "being caught by foreign matter"), and the links and pins in the link mechanism are rusted or seized (hereinafter referred to as an abnormality of the link mechanism section).

However, in the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 58-100086, the measurement data changes due to the fluctuation of the mechanical efficiency from the drive motor to the suspended load. It is very difficult to judge.

On the other hand, in the method disclosed in Japanese Patent Application Laid-Open No. 63-290935, the mechanical distortion signal is directly obtained from the brake. It is not possible to determine whether any abnormalities have occurred in the brakes, and in the end there is no other choice but to an expert.
Further, since the strain gauge has poor durability, regular maintenance of the strain gauge is inevitable.

Further, in any of the methods, the above-mentioned abnormalities cannot be distinguished and detected.

Accordingly, an object of the present invention is to provide an electromagnetic brake abnormality detecting method capable of distinguishing and detecting an electromagnetic brake abnormality, and having a highly stable and highly reliable detection mode. It is in.

[0014]

In order to solve the above-mentioned problems, the present invention is characterized in that, when an electromagnetic coil is energized, a movable core opposed thereto is attracted, and the movement of the movable core releases a brake and cuts off the energization. Then, in the DC electromagnetic brake having a structure in which the movable core separates due to the repulsive force of the braking spring and the brake operates, during energization, the current value increases from the start of energization to the start of movement of the movable core, and the movement of the movable core starts. The current value decreases from the time to the completion of the suction of the movable core, and thereafter, the current value increases again. The change with time of the energizing current is continuously measured. (1) The period from the start of energization to the start of the movable core movement The rising speed of the current value at normal time and the rising speed at normal time; or the time interval from the start of movement of the movable core or any time to the end of adsorption, and normal Detecting the gap abnormality of the movable core with respect to the electromagnetic coil by comparing with the time interval at the time; (2) comparing the current value at the time of completion of the suction with the current value at the time of completion of the suction in the normal state; (3) The current value decreasing gradient from the start of the movement of the movable core to the completion of the attraction of the movable core is compared with the decreasing gradient in the normal state, thereby detecting the brake. An abnormality detection method for a DC electromagnetic brake, comprising: detecting an abnormality in a link mechanism for moving a shoe;

[0015]

[0016]

Further, as a third specific example, the brake shoe is moved by comparing the decrease gradient of the current value from the start of the movement of the movable core to the completion of the attraction of the movable core with the decrease gradient in the normal state. An abnormality of the link mechanism to be performed can be detected.

[0018]

According to the present invention, the time-dependent change of the energizing current during energization is continuously measured, and the measured time-dependent change of the energizing current is compared with the time-dependent change of the energizing current during normal energization. This is to detect abnormalities in the data. That is, the manner in which the energizing current changes over time varies depending on the gap abnormality of the movable core, the abnormality of foreign matter being caught between the electromagnetic coil and the movable core, and the abnormality of the link mechanism for moving the brake arm.

Therefore, each abnormality can be classified based on a change with time of a specific conduction current caused by each abnormality.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows an embodiment in which an abnormality detection device according to the present invention is added via a terminal box 30 to the DC electromagnetic brake having the above-described structure.
FIG. 3 is an electric circuit diagram of the electromagnetic brake. That is, in the present invention, a saving resistor 32 having a resistance R ₁ is provided for the electromagnetic coil 16 having an inductance L connected to a power supply having a voltage E via a contactor 31. A resistor R ₂ is connected in parallel to the electromagnetic coil 16. In the present invention, the contactor 3
A shunt 33 is provided between the electromagnetic coil 1 and the electromagnetic coil 16, and a minute current is taken into an arithmetic unit 35 as a digital signal by an A / D converter 34, and a temporal change of the current value is calculated by the arithmetic unit 35. After processing, each abnormality is discriminated, and if an abnormality is detected, the abnormality is output to a display or an alarm 36, or displayed on a CRT display device 37, and further recorded as necessary. Now, assuming that a current i (t) flows through a circuit constituting the electromagnetic brake, when the electromagnetic brake is energized for traveling of the crane, the current i
(T) shows a change with time generally shown in FIG. 4 from the start of energization. Also, the current i (t) at this time can be expressed by Equation 1.

[0021]

(Equation 1)

In FIG. 4, a period S ₁ is a period in which the movable core 17 has not yet moved, and
In the period S ₂ after 7 starts moving, since the gap is gradually decrease between the electromagnetic coil 16, the inductance L is sequentially increased, as it is apparent from Equation 1, the current i (t) is small Become. In a period S ₃ after the adsorption of the movable core 17 is completed, the current i (t) is increased sequentially. Period S ₃ ends and period S ₄ after it has stabilized
In, the transient phenomenon due to the inductance L stops,
Constant current determined by the resistor R ₁ and the resistor R ₂ flows.

In the present invention, such a temporal change in the supplied current is continuously measured, and an abnormality is detected based on a comparison with a normal state. Since the supplied current shows a specific change according to the type of the abnormality, the following describes each abnormal item. Anomalies in the gap of the movable core When the gap G of the movable core 17 with respect to the electromagnetic coil 16 changes, it appears as a change in the inductance L of the electromagnetic coil 16 and thus the current i (t) changes. For example, when the gap becomes large, the inductance L of the electromagnetic coil 16 becomes small. Therefore, the current change curve when the gap is large has a faster increasing speed of the current value as compared with the normal change curve shown in FIG. The state in which the suction start and the suction completion time of the movable core are also late is shown.

Therefore, the difference of the current value or the rate of change of the current value at an appropriate time within the period S ₁ from the start of energization to the start of suction of the movable core 17 is compared with that at normal time; By setting the suction start time Ts or the suction completion time Te of the movable core 17 based on an appropriate time, and comparing with the normal time,
Gap size or anomalies can be detected.

FIG. 6 shows a current change curve when the gap is normal, and FIG. 7 shows a current change curve when the gap is increased. It can be seen from the comparison between FIG. 6 and FIG. 7 that the above-described phenomenon is remarkably exhibited.

In the case of such a gap abnormality, the gap can be adjusted by adjusting the degree of screwing of the end of the brake rod 6A into the connecting block 7. Although not shown, scales and hands are provided on the outer surface of the connecting block 7 so that the scale can be adjusted while viewing the adjustment range.

Abnormality of foreign matter biting between electromagnetic coil and movable core As shown in FIG. 8, foreign matter M may be bitten between the electromagnetic coil 16 and the movable core 17. In this case, the magnetic resistance is increased by the foreign matter M, the magnetic flux is reduced, and the inductance L is reduced.
Becomes large, and as a result, the adsorption completion time Te
Is larger than the case where no foreign matter is caught.

That is, as shown in FIG. 9, the current value i when the foreign matter M is caught is higher than the minimum value in of the current change curve in the normal state. Therefore,
Whether or not i-in exceeds the reference value K can determine whether or not foreign matter has been caught. In this case, the above-mentioned change in the gap may occur at the same time. Therefore, the change in the gap causes various current change curves C ₁ , C ₂ ,.
Also shows the C _n, curve connecting each local minimum is usually approximated as a straight line X, the biting of the foreign matter can be easily determined by determining the deviation between the approximate line of the minimal value.
Note that the approximate straight line can be obtained by reading the current value when the voltage is changed stepwise in a state where the movable core 17 is attracted.

In the state in which the foreign matter M is caught, as shown in FIG. 9, the current value becomes higher after the movable core 17 is completely attracted. The foreign matter M
Can be eliminated by removing.

Abnormality of the link mechanism for moving the brake shoe In this case, an excessive force is required to suck the movable core 17. Therefore, the time from the start of suction of the movable core 17 to the completion of suction is lengthened. As a result, as shown in FIG. 10, in the normal state, the suction completion time Te ₁ with respect to the suction start time Ts of the movable core 17 is short. Te ₂ becomes longer. Therefore, (Te ₂ −Ts) is compared with (Te ₁ −Ts), and if the deviation is larger than the reference value, it can be determined that the link mechanism is abnormal.

Further, as shown in FIG.
After the maximum value of the suction start is shown, the gradient of the current value decrease line in the region that can be regarded as a straight line up to the minimum value of the adsorption completion can be regarded as constant irrespective of factors such as the aforementioned increase in the gap. . Therefore, as shown in FIG. 10, the slopes of the current value decrease straight lines Y ₁ and Y ₂ are compared, and the decrease straight line Y 1
In the case where the deviation between the _second slope and the slope of the decrease linear Y ₁ in the normal is greater than the reference value, it can be determined that abnormality of the linkage mechanism. This link mechanism is abnormal
The problem can be solved by lubricating the link and pin.

As long as the movable core 17 can be sucked, the curve connecting the minimum values of the current change curves is the same as the current minimum curve at the time of completion of the suction shown in FIG. However, when the link mechanism does not operate and the movable core 17 cannot be attracted, the current change curve is a simple first-order lag curve that does not show the maximum value and the minimum value, and conversely, the phenomenon can be captured.

From the above points, it is possible to detect each abnormality separately and to detect the occurrence of a simultaneous abnormality even when a simultaneous abnormality occurs.

In the electromagnetic brake circuit shown in FIG. 3, if a certain time has elapsed after the end of the suction, the current applied to the electromagnetic coil is reduced to prevent overheating of the electromagnetic coil. According to this, by continuously monitoring i (t), the timing of the voltage drop can be detected, and the overheating and burning of the electromagnetic coil can be prevented. In addition, the method of the present invention can be applied not only to the electromagnetic brake but also to the operation of the DC electromagnetic coil by the same principle and method.

On the other hand, the adjustment of the braking torque by the braking spring 9 can be performed by adjusting the braking spring adjusting nuts 13 for the supporting rods 10 for adjusting the spring force. The stroke of the brake arms 2A, 2B can be performed by positioning the adjustment nuts 14, 14 with respect to the brake arm 2B. Further, the lining for the drum D when the brake is released,
The separation distance 3 can be set by the clearance adjusting bolt 18.

<Experimental Example> (Experimental Example 1) Time-dependent change of the current value when energizing four electromagnetic brakes (O to R) provided in a tilting device of a converter in a steelmaking plant (on the left side) FIG. 12 shows the relationship with time. From FIG. 12, it can be seen that in the change with time of the energizing current of the P electromagnetic brakes, the current value rises faster than the other three brakes, and the suction start of the movable core and the suction completion time are later. This result was displayed by the alarm indicating that the gap was abnormal, so the gap was readjusted. As a result, thereafter, as shown in FIG. 13, each of the four (OR) electromagnetic brakes showed the same change in the current value, and the normal operation of the electromagnetic brake became possible.

(Experimental Example 2) FIG. 14 shows a change curve U of an energizing current when a foreign matter is caught in an electromagnetic brake of an overhead traveling crane hoisting apparatus in a steel factory. When this change curve U was compared with the change curve V when no foreign matter was caught, it was found that the minimum value was large. Then, when the foreign matter was removed, it was clarified that the change in the current value was substantially the same as the change curve V.

[0038]

As is apparent from the above description, according to the present invention, the abnormality of the DC electromagnetic brake can be detected separately, and the detection mode is excellent in stability and high in reliability. And other advantages.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an example in which an abnormality detection device according to the present invention is added to an electromagnetic brake.

FIG. 2 is a plan view of the electromagnetic brake.

FIG. 3 is an electric circuit diagram thereof.

FIG. 4 is a graph showing a temporal change of a current flowing through the circuit.

FIG. 5 is a graph showing a temporal change of a current according to a gap change.

FIG. 6 is a graph showing a temporal change of a current when a gap is normal.

FIG. 7 is a graph showing a temporal change of a current when a gap is abnormal.

FIG. 8 is an explanatory diagram of a state in which a foreign object is caught.

FIG. 9 is a graph showing a temporal change of a current when a foreign substance is caught.

FIG. 10 is a graph showing a temporal change in current when an abnormality occurs in a link mechanism.

FIG. 11 is a graph emphasizing a temporal change in current from the start of moving coil suction to the completion of suction.

FIG. 12 is a graph showing changes over time of currents of four electromagnetic brakes.

FIG. 13 is a graph showing the change over time in the current of four electromagnetic brakes after one brake is adjusted.

FIG. 14 is a graph showing a change with time of a current when a foreign substance is caught.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Brake stand, 2A, 2B ... Brake arm, 3 ... Lining, 4 ... Brake shoe, 6A, 6B ... Brake rod, 9 ... Brake spring, 16 ... Electromagnetic coil, 17 ... Movable core, 33 ... Divider, 34 ... A / D converter, 35 ... arithmetic unit.

Claims (1)

(57) [Claims] When an electric current is applied to an electromagnetic coil, a movable core opposed thereto is attracted, and a brake is released by the movement of the movable core. When the energization is interrupted, the movable core is separated by a repulsive force of a braking spring, and the brake is released. In a DC electromagnetic brake having a structure that operates, during energization, the current value increases from the start of energization to the start of movement of the movable core, and the current value decreases from the start of movement of the movable core to the end of adsorption of the movable core, Thereafter, the temporal change of the energizing current at which the current value increases again is continuously measured. Or by comparing the time interval from the start of movement of the movable core or an arbitrary time to the end of adsorption with the time interval in the normal state, And (2) detecting a foreign object caught between the electromagnetic coil and the movable core by comparing the current value at the time of completion of the suction with the current value at the time of completion of the suction in a normal state. (3) The abnormality of the link mechanism for moving the brake shoe is detected by comparing the decreasing gradient of the current value from the start of the movement of the movable core to the completion of the attraction of the movable core with the decreasing gradient in the normal state. An abnormality detection method for a DC electromagnetic brake, wherein the abnormality is detected separately.