JP7721393B2 - Electric hoist and method for monitoring the electric hoist - Google Patents

Description

The present invention relates to an electric hoist and a method for monitoring the electric hoist.

An electric hoist or other electric lifting machine is an industrial machine that moves a load attached to a crane hook up by winding up a wire rope with a motor-equipped hoisting device, and moves it down by lowering it. The hoist brake is an electromagnetic brake attached to the motor's rotating shaft, and by activating the electromagnetic brake, the motor can be stopped, allowing the load to be held suspended in any position.

An electromagnetic brake consists of a brake wheel fastened to the motor's rotating shaft and a brake disc that is in frictional contact with the brake lining attached to the brake wheel. The brake is activated when the brake wheel and brake disc are in close contact via the brake lining, and conversely, the brake is released when they are not in close contact. The brake disc is driven by a brake lever. The brake mechanism is fastened to the moving core of the solenoid by a link mechanism; passing or stopping current through the solenoid moves the moving core, which also moves the brake lever via the link mechanism.

The brake linings of hoist brakes gradually wear out as the brakes are repeatedly applied. As the amount of wear on the brake lining increases, the friction between the brake wheel and brake disc decreases when braking, which can lead to slippage when stopping a suspended load. Therefore, it is important to regularly inspect the brakes and check the amount of wear on the linings.

Brake inspection methods include having workers disassemble and visually inspect brake components, and calculating the estimated amount of lining wear using information from various sensors installed on the hoist. Estimating lining wear using sensor information eliminates the need to open and inspect the brakes, allowing for constant monitoring. Patent Document 1 describes a known technique for estimating brake lining wear using sensor information.

International Publication No. 2020/044569

Patent Document 1 states that "the wear amount estimation unit estimates the amount of wear of the friction material of the brake disc based on the output of a current sensor that detects the current flowing through the brake coil of the brake device." The friction material here corresponds to the brake lining in this invention. It also states that "as the amount of wear of the friction material increases, the distance between the armature and field core increases during brake operation, and therefore the time required for attraction of the armature becomes longer."

In the configuration described in this document, the output value of the current sensor is a DC current (Figure 4 of Patent Document 1), making it difficult to apply directly to AC-driven electromagnetic brakes. Furthermore, when the electromagnetic brake is driven by a commercial AC power source, the current phase differs for each operation, so there is a need for a method that can detect the amount of brake wear using the same indicator even when the phases differ.

The present invention solves the problems of the prior art described above and provides an electric hoist equipped with an AC-driven electromagnetic brake, and a monitoring direction for the electric hoist that enables the amount of brake wear to be detected using the same indicator even when the current phases are different.

In order to solve the above-mentioned problems, the present invention provides an electric hoist comprising a hoisting motor, an electromagnetic brake unit, a power supply unit that supplies power to the hoisting motor and the electromagnetic brake unit, a diagnostic unit that estimates the wear state of the electromagnetic brake unit, and a diagnostic result output unit,
The electromagnetic brake unit includes a brake wheel connected to the hoisting motor, a brake lining fixed to the brake wheel, a brake disc facing the brake lining, a link mechanism unit that presses the brake disc against the brake lining and releases it, and a brake solenoid that drives the link mechanism unit.
The diagnosis unit includes a current measurement unit that measures the AC current supplied from the power supply unit to the electromagnetic brake unit, a time series data calculation unit that calculates time series data of the AC current values measured by the current measurement unit, a time calculation unit that calculates a time width of time series data calculated by the time series data calculation unit that is equal to or greater than a predetermined threshold, and a brake wear amount estimation unit that estimates the amount of wear of the brake lining based on the time width calculated by the time calculation unit.The diagnosis unit estimates the amount of wear of the brake lining based on data obtained by measuring the AC current supplied from the power supply unit, and outputs an alarm to the diagnosis result output unit when information related to the estimated amount of wear of the brake lining exceeds a predetermined value.

Furthermore, in order to solve the above-mentioned problems, the present invention configures an electric hoisting machine comprising a hoisting motor, an electromagnetic brake unit, a power supply unit that supplies power to the hoisting motor and the electromagnetic brake unit, a diagnostic unit that estimates the wear state of the electromagnetic brake unit, and a diagnostic result output unit. The diagnostic unit estimates the amount of wear of the electromagnetic brake unit based on time-series data for any interval of the AC current value obtained by measuring the AC current supplied to the electromagnetic brake unit from the power supply unit, and outputs an alarm to the diagnostic result output unit when this estimated amount of wear of the electromagnetic brake unit exceeds a preset value.

Furthermore, to solve the above-mentioned problems, in a monitoring method for an electric hoist equipped with a hoisting motor, an electromagnetic brake unit, and a power supply unit that supplies power to the hoisting motor and the electromagnetic brake unit, the electric hoist is further configured to include a diagnostic unit that estimates the wear state of the electromagnetic brake unit, and a diagnostic result output unit, and the diagnostic unit estimates the amount of wear of the electromagnetic brake unit based on time-series data for any interval of the AC current value obtained by measuring the AC current supplied to the electromagnetic brake unit from the power supply unit, and outputs an alarm to the diagnostic result output unit when information related to this estimated amount of wear of the brake unit exceeds a preset value.

According to the present invention, it is possible to estimate the amount of wear of the electromagnetic brake of an electric hoist with high accuracy.
Other objects, configurations and effects of the present invention will become apparent from the following description.

1 is a schematic diagram illustrating an example of a diagnostic system according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing a brake operating state according to the first embodiment. FIG. 4 is a schematic diagram showing a brake release state according to the first embodiment. 4 is a schematic diagram showing a brake operating state when the brake is worn according to the first embodiment. FIG. FIG. 4 is a schematic diagram showing an example of a measurement result of a solenoid current according to the first embodiment. FIG. 4 is a schematic diagram illustrating an example of a calculation result of a time-series data calculation unit according to the first embodiment. FIG. 3 is a schematic diagram illustrating an example of a diagnosis model of a brake wear diagnosis unit according to the first embodiment. FIG. 3 is a schematic diagram showing a brake wear diagnosis flow according to the first embodiment. FIG. 10 is a front view of a display screen that displays that there is no abnormality as a result of the brake wear diagnosis according to the first embodiment. FIG. 10 is a front view of a display screen displaying an abnormality as a result of the brake wear diagnosis according to the first embodiment. FIG. 10 is a front view of a display screen displaying an abnormality as a result of the brake wear diagnosis according to the first embodiment. FIG. 10 is a schematic diagram showing a configuration when an automatic brake adjustment function according to a second embodiment is applied. FIG. 10 is a schematic diagram illustrating an example of a diagnosis result that takes into account an automatic brake adjustment function according to the second embodiment. FIG. 10 is a schematic diagram showing a diagnostic flow taking into consideration an automatic brake adjustment function according to a second embodiment.

The present invention relates to an electric hoist equipped with a brake diagnostic system and a method for monitoring the hoist.

In more detail, the present invention relates to an electric hoist equipped with a brake diagnostic system that includes a current measurement unit that measures the AC current that drives the electromagnetic brake unit, a time series data calculation unit that calculates time series data for each arbitrary interval of the AC current value measured by the current measurement unit, a time calculation unit that calculates the time at which the value of the time series data calculation unit exceeds a threshold value, and a brake wear amount estimation unit that estimates the amount of wear of the electromagnetic brake unit based on the time calculated by the time calculation unit, and a monitoring method for the electric hoist.

An electric hoist equipped with the brake diagnostic system of the present invention makes it possible to estimate the amount of wear on the electromagnetic brake of the electric hoist with high accuracy and issue a warning for maintenance of the electromagnetic brake at an appropriate time.

The following describes in detail the embodiments of the present invention using the drawings. In all drawings used to explain this embodiment, parts with the same functions are designated by the same reference numerals, and repeated explanations will generally be omitted.

However, the present invention should not be construed as being limited to the description of the embodiments shown below. Those skilled in the art will readily understand that the specific configuration can be modified without departing from the spirit or intent of the present invention.

Figure 1 shows a power system diagram of the hoist motor 10 and electromagnetic brake unit 60 of the hoist associated with the electric hoist of this embodiment. A commercial three-phase power source 100 is connected to the hoist motor 10, and the application of three-phase power to the hoist motor 10 causes it to rotate forward and reverse, lifting and lowering a load (not shown). The electromagnetic brake unit 60 includes a brake mechanism unit 20, a link mechanism unit 30, and a brake solenoid 40. Power to the brake solenoid 40 is supplied by branching any two-phase current from the three-phase power source 100.

When current is applied to the hoist motor 10 from the three-phase power supply 100, the brake solenoid 40 is also simultaneously energized. When current is applied to the brake solenoid 40, the brake mechanism 20 releases the rotating shaft of the hoist motor 10 via the link mechanism 30, releasing the brake, allowing the load to rise and fall as the hoist motor 10 rotates.

On the other hand, when the power supply to the hoisting motor 10 is cut off, the current to the brake solenoid 40 is also cut off. This activates the brake mechanism 20, mechanically locking the rotating shaft of the hoisting motor 10 and stopping the load in that position. In this way, the operation of the hoisting motor 10 and the brake solenoid 40 are linked. The detailed operation of the electromagnetic brake unit 60 will be described later.

Next, the configuration of the diagnostic device 50 according to this embodiment will be described. The diagnostic device 50 includes a time series data calculation unit 52, a time calculation unit 53, and a brake wear amount estimation unit 54, and information relating to brake wear estimated by the brake wear amount estimation unit 54 is output to the diagnostic result output unit 55.

In FIG. 1, a current sensor 51 is installed on an electric wire to measure the AC current flowing through the brake solenoid 40. A time series data calculation unit 52 divides the AC current measured by the current sensor 51 into arbitrary intervals and calculates the effective value or standard deviation value to calculate time series data. A time calculation unit 53 calculates the time at which the value of the time series data calculated by the time series data calculation unit 52 is equal to or greater than a certain threshold as a diagnostic feature. A brake wear amount estimation unit 54 estimates the amount of brake wear based on the diagnostic feature extracted by the time calculation unit 53. The estimated results are displayed, for example, on a diagnostic result output unit 55. Details of each calculation method will be described later.

The configuration of the electromagnetic brake unit 60 and its operation when activated (brake solenoid is de-energized) will be described using Figure 2. The brake mechanism 20 of the electromagnetic brake unit 60 includes a brake wheel 21, brake lining 22, brake disc 23, protrusion 23b, and brake lever 24. The link mechanism 30 includes a drive rod 31, drive link 32, fulcrum 33 for drive link 32, and brake spring 34. The brake solenoid 40 includes a coil 41, a movable core 42, and an adjustment screw 44. One end of the brake spring 34, the coil 41, and the adjustment screw 44 are supported by a brake stand 43.

As shown in the figure, a brake wheel 21 of the brake mechanism unit 20 is attached to the portion of the rotating shaft 12 of the hoist motor 10 that is exposed from the motor case 11. A movable brake disc 23 is provided opposite the brake wheel 21. A brake lining 22 is provided on the brake wheel 21, and when the brake disc 23 is pressed against the brake wheel 21 by the link mechanism unit 30, frictional force acts between the brake disc 23 and the brake lining 22, making it possible to lock the rotating shaft 12 of the hoist motor 10. Note that while this embodiment has been described as an example in which there is one brake wheel 21 and one brake disc 23, any number of brake wheels 21 and brake discs 23 may be used.

Next, we will describe the operation of the brake disc 23. The brake disc 23 has a protrusion 23b. The brake lever 24 is able to swing freely around the contact surface with the adjustment screw 44 as a fulcrum. A drive rod 31 is attached to the side of the brake lever 24 opposite the side that contacts the adjustment screw 44. The brake lever 24 also comes into contact with the protrusion 23b located in the center of the brake disc 23.

A compression brake spring 34 is attached to the drive rod 31. When the brake solenoid 40 is not activated, the elastic force of the brake spring 34 causes it to be guided by a linear guide mechanism (not shown) and pushed in the direction of the arrow toward the brake disc 23. As a result, the brake lever 24 rotates counterclockwise in Figure 2, with the point of contact with the adjustment screw 44 as the fulcrum, and presses the brake disc 23 toward the brake wheel 21 via the protrusion 23b, thereby applying the brake.

Using Figure 3, we will explain the operation when the brake is released (brake solenoid 40 is energized). As shown in the figure, a drive link 32 is connected to the drive rod 31, and the other end of the drive link 32 is connected to the movable core 42 of the brake solenoid 40. The movable core 42 reciprocates in the vertical direction of the figure along the coil 41.

In other words, when the coil 41 is not energized, the drive rod 31, which is pushed toward the brake disc 23 by the brake spring 34, and the movable core 42, which is connected by the drive link 32, are floating a distance S from the coil 41, as shown in Figure 2.

On the other hand, when current is applied to the coil 41, the movable core 42 is attracted, resulting in the state shown in Figure 3, and the drive rod 31 is moved in the opposite direction (in the direction of the arrow) from the brake disc 23 via the drive link 32. At this time, the drive rod 31 begins to move in the direction of the arrow when the force attracting the drive rod 31 exceeds the elastic force of the brake spring 34. This releases the brake lever 24 from pressing the protrusion 23b, releasing the contact between the brake wheel 21 and brake disc 23 and releasing the brake.

The brake solenoid 40, which is composed of a coil 41 and a movable core 42, the link mechanism 30, which is composed of a drive rod 31, a drive link 32, and a brake spring 34, and the adjustment screw 44 are fixed to a brake stand 43.

Using Figure 4, we will explain what happens when the brakes are worn. Repeated use of the brakes causes the brake linings 22, located between the brake wheel 21 and the brake disc 23, to wear. If the amount of wear on the brake lining 22 is d, the gap between the brake wheel 21 and the brake disc 23 is G-d (where G is the gap when the brake lining 22 is in good condition). As a result, the position of the protrusion 23b also moves toward the brake wheel 21 by the amount of wear d, so in order to activate the brakes, the brake lever 24 and drive rod 31 must be positioned further forward than normal by an amount corresponding to the amount of wear d on the brake lining 22.

If the amount of advancement of the drive rod 31 at this time is d' (which depends on the amount of wear d of the brake lining 22), the stroke amount of the movable core 42 connected via the drive link 32 is S + d'' (where S is the stroke amount when in good condition).

The effect of brake wear on the link mechanism 30 will now be described. When the brake lining 22 wears by an amount d, the position of the drive rod 31 advances by an amount d' when the brake is applied, extending the stroke of the brake spring 34 and reducing the elastic force of the brake spring 34. As a result, the force with which the drive rod 31, pressed by the brake spring 34, presses against the brake disc 23 via the brake lever 24 also decreases.

When the amount of wear on the brake lining 22 exceeds a certain predetermined value, slippage may occur between the brake lining 22 and the brake disc 23. Therefore, to prevent this slippage from occurring, we will show an example of a method for estimating the amount of wear on the brake lining 22 so that the electromagnetic brake unit 60 can be adjusted before slippage occurs.

Figure 5A is a graph showing the results of measuring the change over time in the AC current (hereafter referred to as the solenoid current) flowing through the coil 41 of the brake solenoid 40. Time 501 represents the transient period immediately after current begins to flow through the coil 41 until the current stabilizes, and time 502 represents the static period during which the current flowing through the coil 41 becomes constant.

5B is a graph showing the standard deviation ST of the solenoid current in a given section t _dlt of the graph in FIG. 5A in a time series. The standard deviation ST rises significantly immediately after the coil 41 is energized, as shown in waveform 511. Thereafter, as the solenoid current stabilizes, the standard deviation ST converges to a constant value, as shown in waveform 512.

Here, the length of the arbitrary section t _dlt may be equal to or greater than one period of the AC current flowing from the three-phase power supply 100 to the coil 41 of the brake solenoid 40 .

5C shows an example of the results of actual measurements of the relationship between the time duration _Tf and the amount of wear of the brake lining 22, where _Tf is the time duration during which the standard deviation value ST exceeds the threshold value 510. As shown in the figure, it can be seen that the time duration _Tf tends to increase as the amount of wear of the brake lining 22 increases. This is because, as the amount of wear of the brake lining 22 increases, the stroke amount of the movable core 42 of the brake solenoid increases, and accordingly, the time from the de-energized state until the attraction of the movable core 42 is completed (corresponding to time 501 in FIG. 5A ) also increases.

Here, if the time width _Tf of the normal range is experimentally determined in advance and the time width _Tf of the normal range is defined as _t2 , then by detecting the timing when the time width _Tf ≥ _t2 , it is possible to predict the limit of normal operation of the electromagnetic brake unit 60 and issue an alarm to notify of an abnormality.

Note that Figure 5B describes an example of detecting an abnormality by determining the time at which the standard deviation value for an arbitrary section exceeds a threshold value, but instead of the standard deviation value, it is also possible to detect an abnormality using time series data of the maximum or minimum value of the solenoid current for each arbitrary section.

This embodiment is based on the new insight described above, and makes it possible to estimate and diagnose the amount of wear on the brake lining 22, predicting an abnormality (when electromagnetic brake maintenance is required) and issuing a warning before an abnormal situation occurs.

FIG. 6 shows a flow chart for diagnosing brake wear according to this embodiment.
In S101, the AC current (hereinafter referred to as the solenoid current) flowing through the coil 41 of the brake solenoid is measured by the current sensor 51, and the time-series data calculation unit 52 of the diagnostic device 50 acquires data such as that shown in Fig. 5A. In addition to a method of measuring by clamping the current sensor 51 to the electric wire, there is also a method of using a value measured by an existing current measurement means (for example, a current sensor used for controlling an inverter).

In S102, the time-series data calculation unit 52 calculates the standard deviation ST of the solenoid current for an arbitrary section t _dlt based on the data acquired in S101, thereby obtaining time-series data of the standard deviation ST as shown in FIG. 5B. As shown in the figure, the standard deviation ST rises significantly immediately after the coil 41 is energized. Thereafter, as the solenoid current stabilizes, the standard deviation ST also converges to a constant value.

In S103, the time calculation unit 53 calculates a time width Tf during which the standard deviation value ST is equal to or greater than a preset threshold value, based on the standard deviation value ST of the arbitrary section _tdlt of the solenoid current calculated by the time series data calculation unit _52. The threshold value is set to a value greater than a fixed value at which the standard deviation value ST converges.

In S104, the brake wear amount estimation unit 54 determines whether the time range _Tf is within the normal range based on the time range _Tf during which the standard deviation value ST calculated by the time calculation unit 53 is equal to or greater than a preset threshold. As explained in FIG. 5C , if the normal range time range Tf is defined as _Tf < _t2 based on the tendency for the time range _Tf to increase as the amount of wear of the brake lining 22 increases, in S104, if the time range _Tf < _t2 , the time range _Tf is determined to be within the normal range (Yes), and if the time range _Tf ≥ _t2 , the time range Tf is determined to be abnormal (No).

If it is determined in S104 that the time width _Tf is within the normal range (Yes), the process proceeds to S105, where the diagnosis result output unit 55 displays "Normal" in the display section 553 of the brake wear diagnosis result display area 552 on the display screen 551, as shown in Fig. 7A, and then the process proceeds to S107 to determine whether or not to continue measurement. If the answer is Yes in S107, the process returns to S101 and continues measurement, and if the answer is No, the measurement ends.

On the other hand, if it is determined in S104 that the time width _Tf is abnormal (No), the process proceeds to S106, where the diagnosis result output unit 55 displays "Abnormal" in the display unit 553 of the brake wear diagnosis result display area 552 on the display screen 551 as shown in Fig. 7B, issues a warning for electromagnetic brake maintenance, and ends the measurement. At this time, in addition to displaying "Abnormal" on the display unit 553, the diagnosis result output unit 55 may also sound an alarm. Furthermore, instead of the display in Fig. 7B, specific details of measures to be taken to address the abnormality, such as "replace the brake lining," may be displayed as shown in Fig. 7C.

In this embodiment, by constantly measuring the AC current (solenoid current) flowing through the coil 41 of the brake solenoid 40, it is possible to estimate and diagnose the amount of wear on the brake lining 22, and to issue a maintenance warning for the electromagnetic brake of the electric hoist at the appropriate time.

Some hoists are equipped with a function that automatically adjusts the pressing force of the drive rod 31 when the brake wear exceeds a certain level. Therefore, this example describes a brake wear diagnosis method for a hoist equipped with an automatic adjustment function.

The automatic adjustment function will be explained using Figure 8. In the state shown in Figure 4 described in Example 1, the amount of displacement of the brake spring 34 increases due to the wear amount d of the brake lining 22, and the pressing force of the brake spring 34 on the protrusion 23b is accordingly weakened. To restore this weakened pressing force (the elastic force of the brake spring 34), in this example, the adjustment screw 44 is rotated using a drive device (not shown) to adjust the position of the branch relative to the brake lever 24.

That is, as shown in Figure 8, the adjustment screw 44 is rotated using a drive device (not shown) to press the brake lever 24 toward the brake disc 23. When the pressing amount by the adjustment screw 44 is _d1 '', the drive rod 31 moves _d1 ' in the direction compressing the brake spring 34, with the protrusion 23b as the fulcrum. By making this adjustment, the spring length of the brake spring 34 when not energized (when the brake is applied) can be made to be the same value as in the normal state shown in Figure 2 described in Example 1. As a result, the elastic force of the brake spring 34 also becomes the same value as in the normal state, and the force pressing the brake disc 23 becomes the same as in the normal state. This makes it possible to maintain the brake in a sound condition even if the brake lining 22 is worn.

Furthermore, by adjusting the adjustment screw 44 and moving the drive rod 31 by _d1 ', the stroke amount S of the movable core 42 is reduced by _d1 ''' via the drive link 32. When the stroke amount S of the movable core 42 is reduced, the time width _Tf shown in Figure 5C in Example 1 also reduces from _t2 to _t1 . However, if the amount of wear of the brake lining 22 exceeds a certain value, the braking force cannot be restored even using the automatic brake adjustment function using the adjustment screw 44. Therefore, it is necessary to diagnose the brake wear state before the braking force cannot be restored.

9 is a graph showing the relationship between the number of brake adjustments and the brake pressing time duration _Tf , where _Tf is the time duration during which the standard deviation value ST of the arbitrary section _tdlt of the solenoid current becomes greater than the threshold value 510, as explained in the first embodiment with reference to FIGS.

In waveform 901, immediately after automatic brake adjustment is performed by driving adjustment screw 44 with a driving means (not shown), the value of _Tf reaches the minimum value _t1 , and as the number of times the brake is used increases, it increases for the same reasons as described in Example 1. When the value of _Tf reaches a preset upper limit value _t2 (times 911, 912, and 913 in the example of FIG. 9), automatic brake adjustment is performed by adjusting adjustment screw 44 using a driving device (not shown), and the set time width _Tf of brake pressing returns to the minimum value _t1 .

When the number of times automatic brake adjustment is required reaches a preset number (N times in the case of Figure 9) (time 920 in Figure 9), the brake wear amount estimation unit 54 outputs an abnormality signal to the diagnosis result output unit 55.

Figure 10 shows the flow for diagnosing brake wear when using the automatic brake adjustment function based on this embodiment. First, in S200, the number of adjustments n is set to zero. The following steps S201 to S203 are the same as steps S101 to S103 of the brake wear diagnosis flow described in Figure 6 for Example 1, and are common regardless of whether the automatic brake adjustment function is present or not, so a description thereof will be omitted.

In S204, the brake wear amount estimation unit 54 checks whether _Tf calculated by the time calculation unit 53 in S203 has reached the upper limit value _t2 of the preset time width, and if it is determined that _Tf has not yet reached _t2 (No), the process proceeds to S208, where a normal signal is output to the diagnosis result output unit 55, and the process proceeds to S209, where it is checked whether to continue measurement, and if Yes, the process returns to S201. If No, the measurement ends.

If the answer is Yes, the diagnostic result output unit 55 that receives the normal signal will display "Normal" in the display section 553 of the brake wear diagnostic result display area 552 on the display screen 551, as shown in Figure 7A, just as in Example 1.

On the other hand, if it is determined in S204 that _Tf has reached _t2 (Yes), the process proceeds to S205, where the brake wear amount estimation unit 54 determines whether the number of adjustments n has reached a preset upper limit value N.

If it is determined that the number of adjustments n has not reached N (No), the process proceeds to S206, where the adjustment screw 44 is adjusted using a drive device (not shown) as described in FIG. 8 to perform automatic brake adjustment. After this automatic brake adjustment is completed, the process proceeds to S207, where 1 is added to the number of adjustments n, and to S208, where a normal signal is output to the diagnosis result output unit 55. The process proceeds to S209, where it is checked whether to continue measurement, and if Yes, the process returns to S201. By performing automatic brake adjustment in S206, the established time width _Tf of brake pressing returns to _t1 . On the other hand, if No in S209, measurement is terminated.

If it is determined in S205 that the number of adjustments n has reached N (Yes), the process proceeds to S210, where an abnormality signal is output to the diagnosis result output unit 55 (an abnormality alert), and measurement ends. Upon receiving the abnormality alert signal in S210, the diagnosis result output unit 55 displays "Abnormal" on the display unit 553 as shown in Figure 7B, or "Replace brake lining" as shown in Figure 7C.

By diagnosing the time width _Tf calculated from the solenoid current as a feature quantity using the diagnostic flow described in this embodiment, it becomes possible to perform maintenance according to the actual wear state of the brakes, without being affected by differences in the actual wear speed of the brakes (the wear speed in the N-2 to N-1 section is faster than that in the N-3 to N-2 section in Figure 9).

This eliminates the need for excessively frequent maintenance, contributing to reduced maintenance costs and downtime costs. Furthermore, unlike regular maintenance, even if brake wear progresses rapidly, it is possible to diagnose brake wear at any time, which also contributes to reducing downtime costs caused by hoist brake failure.

Also, while the brakes described so far have been applied to the hoisting motor of a hoist, they can also be applied to brakes used in the traverse section and traveling section. Furthermore, as long as the electromagnetic brake operates on a similar drive principle, this technology can be applied to applications other than hoists and hoists.

The invention made by the inventor has been specifically described above based on examples, but it goes without saying that the present invention is not limited to the above examples and can be modified in various ways without departing from the spirit of the invention. For example, the above examples have been described in detail to clearly explain the invention, and the invention is not necessarily limited to those that include all of the described configurations. Furthermore, it is possible to add, delete, or replace part of the configuration of each example with other configurations.

10: Hoisting motor 11: Motor case 12: Rotating shaft
20: Brake mechanism section 21: Brake wheel 22: Brake lining 23: Brake disc 23b: Protrusion 24: Brake lever 30: Link mechanism section 31: Drive rod 32: Drive link 34: Brake spring 40: Brake solenoid 41: Coil
42: Movable core 43: Brake stand 44: Adjusting screw 50: Diagnostic device 51: Current sensor 52: Time series data calculation unit 53: Time calculation unit 54: Brake wear amount estimation unit 55: Diagnostic result output unit 60: Electromagnetic brake unit 100: Three-phase power supply

Claims (13)

An electric hoist including a hoisting motor, an electromagnetic brake unit, a power supply unit that supplies power to the hoisting motor and the electromagnetic brake unit, a diagnostic unit that estimates a wear state of the electromagnetic brake unit, and a diagnostic result output unit,
the electromagnetic brake unit includes a brake wheel connected to the hoisting motor, a brake lining fixed to the brake wheel, a brake disc facing the brake lining, a link mechanism unit that presses and releases the brake disc against the brake lining, and a brake solenoid that drives the link mechanism unit,
the diagnosis unit includes a current measurement unit that measures the AC current supplied from the power supply unit to the electromagnetic brake unit; a time series data calculation unit that calculates time series data of the AC current values measured by the current measurement unit; a time calculation unit that calculates a time width of the time series data calculated by the time series data calculation unit that is equal to or greater than a predetermined threshold; and a brake wear amount estimation unit that estimates a wear amount of the brake lining based on the time width calculated by the time calculation unit, wherein the electric hoist estimates the wear amount of the brake lining based on data obtained by measuring the AC current supplied from the power supply unit to the electromagnetic brake unit, and outputs an alarm to the diagnosis result output unit when information regarding the estimated wear amount of the brake lining exceeds a predetermined value. The electric hoist according to claim 1 ,
the brake wear amount estimation unit determines whether or not the number of adjustments of the link mechanism unit, which presses and releases the brake disc against the brake lining, has reached a predetermined number of times based on the amount of wear of the brake lining estimated based on the time width calculated by the time calculation unit, and outputs an alarm to the diagnosis result output unit when the number of adjustments has reached the predetermined number of times. The electric hoist according to claim 1 ,
The time series data calculation unit calculates, as the time series data, time series data of an effective value or a standard deviation value of the AC current value measured by the current measurement unit for each predetermined time interval. The electric hoist according to claim 1 ,
The time series data calculation unit calculates, as the time series data, time series data of a maximum value or a minimum value for each arbitrary section of the AC current value measured by the current measurement unit. An electric hoist including a hoisting motor, an electromagnetic brake unit, a power supply unit that supplies power to the hoisting motor and the electromagnetic brake unit, a diagnostic unit that estimates a wear state of the electromagnetic brake unit, and a diagnostic result output unit,
the diagnostic unit estimates the amount of wear of the electromagnetic brake unit based on time-series data for each arbitrary interval of the AC current value obtained by measuring the AC current supplied from the power supply unit to the electromagnetic brake unit, and outputs an alarm to the diagnostic result output unit when the estimated amount of wear of the electromagnetic brake unit exceeds a preset value. The electric hoist according to claim 5 ,
The diagnostic unit
a current measuring unit that measures an AC current supplied from the power supply unit to the electromagnetic brake unit;
a time-series data calculation unit that calculates time-series data of an effective value or a standard deviation value for each arbitrary section of the AC current value measured by the current measurement unit;
a time calculation unit that calculates a time width of the time series data calculated by the time series data calculation unit that is equal to or greater than a predetermined threshold;
a brake wear amount estimation unit that estimates the amount of wear of the electromagnetic brake unit based on the time width calculated by the time calculation unit. The electric hoist according to claim 6 ,
The time series data calculation unit calculates, as the time series data, time series data of an effective value or a standard deviation value of the AC current value measured by the current measurement unit for each predetermined time interval. The electric hoist according to claim 6 ,
The time series data calculation unit calculates, as the time series data, time series data of a maximum value or a minimum value for each arbitrary section of the AC current value measured by the current measurement unit. A monitoring method for an electric hoist including a hoisting motor, an electromagnetic brake unit, and a power supply unit that supplies power to the hoisting motor and the electromagnetic brake unit,
The electric hoist further includes a diagnostic unit that estimates a wear state of the electromagnetic brake unit, and a diagnostic result output unit ,
the diagnostic unit estimates the amount of wear of the electromagnetic brake unit based on time series data for each arbitrary interval of the AC current value obtained by measuring the AC current supplied from the power supply unit to the electromagnetic brake unit, and outputs an alarm to the diagnostic result output unit when information regarding the estimated amount of wear of the electromagnetic brake unit exceeds a preset value. A monitoring method for an electric hoist according to claim 9 ,
a diagnostic unit that measures the AC current supplied from the power supply unit to the electromagnetic brake unit, calculates time series data of the AC current values obtained by the measurement, calculates a time width of the calculated time series data that is equal to or greater than a predetermined threshold, and estimates the amount of wear of the electromagnetic brake unit based on the calculated time width. A monitoring method for an electric hoist according to claim 10 ,
A monitoring method for an electric hoist, characterized in that the calculation of the time series data of the AC current value is carried out by calculating time series data of an effective value or a standard deviation value of the AC current value obtained by the measurement for each predetermined time interval. A monitoring method for an electric hoist according to claim 10 ,
A monitoring method for an electric hoist, characterized in that the calculation of the time series data of the AC current value is carried out by calculating time series data of maximum or minimum values of the AC current value obtained by the measurement for each predetermined time interval. A monitoring method for an electric hoist according to claim 9 ,
the electromagnetic brake unit includes a brake wheel connected to the hoisting motor, a brake lining fixed to the brake wheel, a brake disc facing the brake lining, a link mechanism unit that presses and releases the brake disc against the brake lining, and a brake solenoid that drives the link mechanism unit,
a diagnostic unit that estimates the amount of wear of the brake lining based on the time series data obtained by measuring the AC current supplied to the electromagnetic brake unit, and outputs an alarm to the diagnostic result output unit when the number of adjustments of the link mechanism unit that presses and releases the brake disc against the brake lining based on the estimated amount of wear of the brake lining reaches a predetermined number.