Electric hoist and method for monitoring the electric hoist

Abstract

To make it possible to detect a wear amount of a brake of an electrically-driven hoist using the same index even when current phases are different.SOLUTION: An electrically-driven hoist includes a hoisting motor, an electromagnetic brake part, a power supply part for supplying power to the hoisting motor and the electromagnetic brake part, a diagnostic part for estimating the state of wear of the electromagnetic brake part, and a diagnosis result output part. The electromagnetic brake part 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 for pressing and releasing the brake disc to and from the brake lining, and a brake solenoid for driving the link mechanism. The diagnostic part estimates the wear amount of the brake lining on the basis of data obtained by measuring an AC current supplied to the electromagnetic brake part from the power supply part, and when a preset value is exceeded, outputs an alarm to the diagnostic result output part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electric hoist and a method for monitoring an electric hoist. [Background technology]

[0002] Electric hoists and other electric hoists are industrial machines that raise and lower a load attached to a crane hook by using a motor-equipped hoisting device to wind up a wire rope, and then lower it to lower the load.The hoist brake is an electromagnetic brake attached to the motor's rotating shaft, and by operating the electromagnetic brake, the motor can be stopped, allowing the load to be held suspended in any position.

[0003] 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 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; by passing or stopping current through the solenoid, the moving core moves, and the brake lever also moves through the link mechanism.

[0004] The brake lining of a hoist brake gradually wears out as the brake is repeatedly applied. As the wear on the brake lining increases, the friction between the brake wheel and brake disc decreases when braking, which can cause slippage when stopping a suspended load. Therefore, it is important to regularly inspect the brake parts and check the wear on the lining.

[0005] Brake inspection methods include a method in which an operator disassembles brake components and visually inspects them, and a method in which an estimated amount of lining wear is calculated using information from various sensors installed on a hoist. Methods that estimate the amount of lining wear using sensor information do not require open inspection of the brakes, making it possible to monitor them constantly. The technology described in Patent Document 1 is known as a method for estimating the amount of brake lining wear using sensor information. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 044569 Summary of the Invention [Problem to be solved by the invention]

[0007] 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 the field core during braking increases, and therefore the time required for attraction of the armature becomes longer."

[0008] In the configuration described in the document, the output value of the current sensor is a DC current (Figure 4 of Patent Document 1), making it difficult to apply as is to an AC-driven electromagnetic brake. Furthermore, when the electromagnetic brake is driven by a commercial AC power source, the phase of the current differs for each operation, so there is a need for a method that can detect the amount of brake wear using the same index even when the phases differ.

[0009] 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 an electric hoist and a monitoring direction for the electric hoist that make it possible to detect the amount of brake wear using the same indicator even when the current phase is different. [Means for solving the problem]

[0010] 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. 、 and The electromagnetic brake unit consists of 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 that presses and releases the brake disc against the brake lining, and a brake solenoid that drives the link mechanism. and, Equipped with 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 that is equal to or greater than a predetermined threshold value from the time series data calculated by the time series data calculation unit; 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; The amount of wear of the brake lining is estimated based on data obtained by measuring the AC current supplied from the power supply unit to the electromagnetic brake unit, and an alarm is output to the diagnostic result output unit when information regarding this estimated amount of wear of the brake lining exceeds a preset value.

[0011] Furthermore, in order to solve the problems of the above technique, the present invention configures 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 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 each arbitrary section 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 this estimated amount of wear of the electromagnetic brake unit exceeds a preset value.

[0012] Furthermore, in order 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 each arbitrary section 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 related to the estimated amount of wear of the brake unit exceeds a preset value. [Effects of the Invention]

[0013] 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. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing an example of a diagnostic system according to a first embodiment of the present invention. [Figure 2] 3 is a schematic diagram showing a brake operating state according to the first embodiment. FIG. [Figure 3] FIG. 3 is a schematic diagram showing a brake release state according to the first embodiment. [Figure 4] 4 is a schematic diagram showing a brake operating state when the brake is worn according to the first embodiment. FIG. [Figure 5A] 4 is a schematic diagram showing an example of the results of measuring a solenoid current according to the first embodiment. FIG. [Figure 5B] 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. [Figure 5C] 3 is a schematic diagram showing an example of a diagnosis model of a brake wear diagnosis unit according to the first embodiment. FIG. [Figure 6] FIG. 2 is a schematic diagram showing a brake wear diagnosis flow according to the first embodiment. [Figure 7A]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. [Figure 7B] FIG. 10 is a front view of a display screen that displays an abnormality as a result of the brake wear diagnosis according to the first embodiment. [Figure 7C] FIG. 10 is a front view of a display screen that displays an abnormality as a result of the brake wear diagnosis according to the first embodiment. [Figure 8] FIG. 10 is a schematic diagram showing a configuration when an automatic brake adjustment function according to a second embodiment is applied. [Figure 9] FIG. 10 is a schematic diagram showing an example of a diagnosis result taking into consideration an automatic brake adjustment function according to the second embodiment. [Figure 10] FIG. 10 is a schematic diagram showing a diagnostic flow taking into consideration an automatic brake adjustment function according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention relates to an electric hoist equipped with a brake diagnostic system and a method for monitoring the hoist.

[0016] More specifically, the present invention relates to an electric hoist equipped with a brake diagnostic system having 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 becomes equal to or greater than 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 an electric hoist.

[0017] According to an electric hoist equipped with the brake diagnostic system of the present invention, it is possible to estimate the amount of wear of the electromagnetic brake part of the electric hoist with high accuracy and issue a warning for maintenance of the electromagnetic brake part at an appropriate time.

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all drawings for explaining the present embodiments, components having the same functions are assigned the same reference numerals, and repeated explanations thereof will be omitted as a general rule.

[0019] 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 configurations can be modified without departing from the spirit or intent of the present invention. [Example]

[0020] 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, thereby hoisting up and lowering a suspended 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.

[0021] When current is applied to the hoist motor 10 from the three-phase power supply 100, current is also applied to the brake solenoid 40 at the same time. 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, thereby releasing the brake, and the suspended load can be raised and lowered as the hoist motor 10 rotates.

[0022] On the other hand, when the power supply to the hoist motor 10 is cut off, the current to the brake solenoid 40 is also cut off. This activates the brake mechanism unit 20, mechanically locking the rotating shaft of the hoist motor 10 and stopping the load in that position. In this way, the operations of the hoist motor 10 and the brake solenoid 40 are linked. The detailed operation of the electromagnetic brake unit 60 will be described later.

[0023] Next, a 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. Information relating to brake wear estimated by the brake wear amount estimation unit 54 is output to a diagnostic result output unit 55.

[0024] In FIG. 1, a current sensor 51 is installed on an electric wire to measure the AC current flowing through a 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 becomes 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 result is displayed, for example, on a diagnostic result output unit 55. Details of each calculation method will be described later.

[0025] The configuration of the electromagnetic brake unit 60 and its operation when activated (the 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, a brake lining 22, a brake disc 23, a protrusion 23b, and a brake lever 24. The link mechanism 30 includes a drive rod 31, a drive link 32, a fulcrum 33 for the drive link 32, and a 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.

[0026] As shown in the figure, a brake wheel 21 of a brake mechanism unit 20 is attached to a 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, a 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, although the present embodiment has been described as an example in which there is one brake wheel 21 and one brake disc 23, the number of brake wheels 21 and brake discs 23 can be any number.

[0027] Next, the operation of the brake disc 23 will be described. The brake disc 23 is provided with 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 provided in the center of the brake disc 23.

[0028] A compression type brake spring 34 is attached to the drive rod 31, and when the brake solenoid 40 is not activated, the elastic force of the brake spring 34 causes the brake lever 24 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 FIG. 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.

[0029] The operation when the brake is released (brake solenoid 40 is energized) will be described using Figure 3. As shown in the figure, a drive link 32 is connected to a drive rod 31, and the other end of the drive link 32 is connected to a movable core 42 of the brake solenoid 40. The movable core 42 reciprocates along a coil 41 in the vertical direction in the figure.

[0030] 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.

[0031] 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 (the direction of the arrow) from the brake disc 23 via the drive link 32. At this time, the drive rod 31 starts moving in the direction of the arrow at the timing when the force attracting the drive rod 31 exceeds the elastic force of the brake spring 34. As a result, the brake lever 24 is released from pressing the protrusion 23b, the brake wheel 21 and the brake disc 23 are no longer in close contact with each other, and the brake is released.

[0032] The brake solenoid 40 consisting of the coil 41 and the movable core 42, the link mechanism 30 consisting of the drive rod 31, the drive link 32 and the brake spring 34, and the adjustment screw 44 are fixed to a brake stand 43.

[0033] Using Figure 4, we will explain the state of the brake when it is worn. Repeated use of the brake causes the brake lining 22, which is provided between the brake wheel 21 and the brake disc 23, to wear. If the amount of wear of the brake lining 22 is d, the gap between the brake wheel 21 and the brake disc 23 becomes Gd (the gap when the brake lining 22 is in good condition is G). As a result, the position of the protrusion 23b also moves toward the brake wheel 21 by the amount of wear d, so that in order to apply the brake, the brake lever 24 and the drive rod 31 must be positioned further forward than normal by an amount corresponding to the amount of wear d of the brake lining 22.

[0034] If the amount of advance 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'' (which is the stroke amount S when in a healthy state).

[0035] 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 the brake disc 23 via the brake lever 24 also reduces.

[0036] When the amount of wear of the brake lining 22 exceeds a certain predetermined value, slippage may occur between the brake lining 22 and the brake disc 23. In order to prevent this slippage from occurring, an example of a method for estimating the amount of wear of the brake lining 22 will be described below, which will enable adjustment of the electromagnetic brake unit 60 before slippage occurs.

[0037] 5A is a graph showing the results of measuring the change over time in the AC current (hereinafter referred to as the solenoid current) flowing through the coil 41 of the brake solenoid 40. The time 501 indicates the transient period immediately after the current starts to flow through the coil 41 until the current stabilizes, and the time 502 indicates the static period when the current flowing through the coil 41 becomes constant.

[0038] FIG. 5B shows the solenoid current in the graph of FIG. 5A at an arbitrary section t dlt 5 is a graph showing the standard deviation value ST of the solenoid current Vcc in a time series. The standard deviation value ST rises significantly as shown in waveform 511 immediately after the solenoid current Vcc is energized. Thereafter, as the solenoid current stabilizes, the standard deviation value ST converges to a constant value as shown in waveform 512.

[0039] Here, any interval t dlt The length of the period 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.

[0040] The time period during which the standard deviation value ST is greater than the threshold value 510 is defined as T f When the time span T f 5C shows an example of the results of measuring the relationship between the time width T f 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 non-energized state until the attraction of the movable core 42 is completed (corresponding to time 501 in FIG. 5A) also increases.

[0041] Here, the normal range time T f is experimentally obtained in advance, and the normal range time width T f is defined as t2, the time span T f By detecting the timing when t2 or more is reached, it is possible to predict the limit of normal operation of the electromagnetic brake unit 60 and issue an abnormality alert.

[0042] In addition, in FIG. 5B, an example of detecting an abnormality is explained in which the time at which the standard deviation value of an arbitrary section becomes greater than a threshold is obtained from the standard deviation value of the arbitrary section, but instead of the standard deviation value, an abnormality may be detected using time series data of the maximum or minimum value of the solenoid current for each arbitrary section.

[0043] This embodiment is based on the new concept described above, and makes it possible to estimate and diagnose the amount of wear of the brake lining 22, and to predict and issue an alarm about an abnormality (time for electromagnetic brake maintenance) before an abnormal situation occurs.

[0044] FIG. 6 shows a flow chart for diagnosing brake wear according to this embodiment. In S101, the AC current (hereinafter referred to as solenoid current) flowing through coil 41 of the brake solenoid is measured by current sensor 51, and data such as that shown in Fig. 5A is acquired by time-series data calculation unit 52 of diagnostic device 50. In addition to a method of measuring by clamping current sensor 51 to an electric wire, there is also a method of using a value measured by existing current measurement means (for example, a current sensor used for controlling an inverter).

[0045] In S102, the time series data calculation unit 52 calculates the solenoid current in an arbitrary section t based on the data acquired in S101. dlt The standard deviation ST of the solenoid current is calculated to obtain the time series data of the standard deviation ST shown in Figure 5B. As shown in the figure, the standard deviation ST rises significantly immediately after the solenoid current is energized. Thereafter, as the solenoid current stabilizes, the standard deviation ST also converges to a constant value.

[0046] In step S103, the time series data calculation unit 52 calculates the solenoid current in an arbitrary section t dlt Based on the standard deviation value ST, the time calculation unit 53 calculates the time duration T during which the standard deviation value ST is equal to or greater than a preset threshold value. f The threshold is set to a value greater than the fixed value at which the standard deviation value ST converges.

[0047] In S104, based on the time width T during which the standard deviation value ST calculated by the time calculation unit 53 is equal to or greater than a preset threshold value, the brake wear amount estimation unit 54 determines whether the time width T f is within the normal range. As described in FIG. 5C, based on the tendency that the time width T f increases as the wear amount of the brake lining 22 increases, if the time width T f within the normal range is defined as <t2, in S104, when the time width T f <t2, it is determined that the time width T f is within the normal range (Yes), and when the time width T f becomes ≧t2, it is determined as abnormal (No). f ≧t2, it is determined as abnormal (No).

[0048] If in S104 it is determined that the time width T f is within the normal range (Yes), the process proceeds to S105. As shown in FIG. 7A, in the diagnosis result output unit 55, "Normal" is displayed on the display unit 553 in the brake wear diagnosis result display area 552 of the display screen 551. Next, the process proceeds to S107 to determine whether to continue the measurement. If Yes in S10​​​​​​​​​According to 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 it is possible to issue a maintenance warning for the electromagnetic brake of the electric hoist at an appropriate time. [Example]

[0051] Some hoists are equipped with a function for automatically adjusting the pressing force of the drive rod 31 when the amount of brake wear reaches a certain level. Therefore, in this embodiment, a brake wear diagnosis method for a hoist equipped with an automatic adjustment function will be described.

[0052] The automatic adjustment function will be explained using Figure 8. In the state shown in Figure 4 described in the first embodiment, 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 weakened accordingly. In order to restore this weakened pressing force (elastic force of the brake spring 34), in this embodiment, the position of the branch relative to the brake lever 24 can be adjusted by rotating the adjustment screw 44 using a drive device (not shown).

[0053] That is, as shown in FIG. 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 de-energized (when the brake is applied) can be made to be the same as that in the normal state shown in FIG. 2 described in the first embodiment. As a result, the elastic force of the brake spring 34 also becomes the same as that in the normal state, and the force pressing the brake disc 23 becomes the same as that in the normal state. This makes it possible to maintain the brake in a sound condition even when the brake lining 22 is worn.

[0054] Furthermore, by adjusting the adjusting 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 T shown in FIG. 5C in the first embodiment is reduced. f The wear of the brake lining 22 also decreases 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 by using the automatic brake adjustment function with the adjustment screw 44. Therefore, it is necessary to diagnose the brake wear state before the braking force cannot be restored.

[0055] Figure 9 shows the relationship between the number of brake adjustments and the brake pressing time T f 1 is a graph showing the relationship between the brake pressing time T f is the arbitrary section t of the solenoid current described in the first embodiment with reference to FIGS. 5A and 5B. dlt The time period during which the standard deviation value ST of the signal is greater than the threshold value 510.

[0056] The waveform 901 shows that immediately after the automatic brake adjustment is performed by driving the adjustment screw 44 with a driving means (not shown), the T f The value of T reaches a minimum value t1, and as the number of times the brake is used increases, it increases for the same reasons as explained in the first embodiment. f When the value of the brake pressure reaches a preset upper limit value t2 (in the example of FIG. 9, the time points 911, 912, and 913), the adjusting screw 44 is adjusted using a driving device (not shown) to automatically adjust the brake, thereby setting the brake pressing time width T f returns to the minimum value t1.

[0057] When the number of times that 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.

[0058] 10 shows a flow for diagnosing brake wear when the automatic brake adjustment function according to this embodiment is used. 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 FIG. 6 in the first embodiment, and are common regardless of whether the automatic brake adjustment function is used or not, so a description thereof will be omitted.

[0059] In S204, the time T calculated by the time calculation unit 53 in S203 is f The brake wear amount estimating unit 54 checks whether or not T has reached the upper limit value t2 of the preset time width. f If it is determined that t2 has not yet been reached (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 the measurement, and if the answer is Yes, the process returns to S201. If the answer is No, the measurement is ended.

[0060] If Yes, the diagnostic result output unit 55 that receives the normal signal displays "Normal" on the display unit 553 of the brake wear diagnostic result display area 552 on the display screen 551, as shown in Figure 7A, as in Example 1.

[0061] On the other hand, S204 T f If it is determined that the number of adjustments n 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.

[0062] If it is determined that the number of adjustments n has not reached N (No), the process proceeds to S206, where the brake is automatically adjusted by adjusting the adjustment screw 44 using a drive device (not shown) as explained in FIG. 8. After this automatic adjustment of the brake is completed, the process proceeds to S207, where 1 is added to the number of adjustments n, where a normal signal is output to the diagnosis result output unit 55, and where a check is made to see if measurement should be continued. If the answer is Yes, the process returns to S201. By performing the automatic adjustment of the brake in S206, the set time width T of the brake pressing is f On the other hand, if the answer is No in S209, the measurement is terminated.

[0063] 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 is issued), and measurement ends. Upon receiving the abnormality issue signal in S210, the diagnosis result output unit 55 displays "Abnormal" on the display unit 553 as shown in Fig. 7B or "Replace brake lining" as shown in Fig. 7C.

[0064] The time width T calculated from the solenoid current in the diagnostic flow described in this embodiment f By diagnosing this as a feature, it becomes possible to carry out maintenance according to the actual state of brake wear, 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).

[0065] This eliminates the need for excessively frequent maintenance, contributing to reduced maintenance costs and downtime costs. Also, unlike regular maintenance, even if brake wear progresses rapidly, it is possible to diagnose brake wear at any time, which contributes to reducing downtime costs caused by hoist brake failure.

[0066] Although the brake described above has been applied to the hoisting motor of a hoist, it 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 more than just hoists and hoists.

[0067] The invention made by the inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the invention. For example, the above embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0068] 10····Hoisting motor 11···Motor case 12···Rotating shaft 20 Brake mechanism 21 Brake wheel 22 Brake lining 23 Brake disc 23b Projection 24 Brake lever 30 Link mechanism 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 section 53... Time calculation section 54... Brake wear amount estimation section 55... Diagnostic result output section 60... Electromagnetic brake section 100... Three-phase power supply

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

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