Method for testing the braking force of disc-type electromagnetic brakes

Abstract

To provide a braking force inspection method of a disk type electromagnetic brake capable of obtaining a braking torque prediction value which can be evaluated in inspection by using a measured value of an element affecting the brake braking force which can be easily measured.SOLUTION: A braking force inspection method includes a calculation formula setting step for previously setting a regression formula in which braking torque (Nm) is an objective variable and at least static friction torque (Nm) is an explanatory variable as a calculation formula acquiring a prediction value of the braking torque at the time of subsequent inspection, with respect to a disk type electromagnetic brake provided in a device to be an inspection object. The calculation formula setting step includes: an actual measurement step in which a braking torque measurement step and a measurement step of the explanatory variable, which includes at least a step of measuring the static friction torque at the time of starting manual rotation by a torque wrench with respect to a motor rotation shaft from a stop state of the motor, are repeated plural times; and a regression analysis step for determining a regression coefficient and an intercept of the explanatory variable by performing a regression analysis regarding to all measured values obtained by the actual measurement step so as to obtain the regression formula.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for inspecting the braking force of a disk-type electromagnetic brake, such as an elevator hoisting machine. Specifically, when inspecting the brake braking force, the measured value of the static friction torque by a torque wrench that can be measured with a relatively simple operation, or the measured value of the static friction torque, the measured value of the brake surface temperature, and the measured value of the brake air gap are applied, and a calculation formula for obtaining a predicted value of the braking torque is preset. Further, the present invention is a method for inspecting the braking force of a disk-type electromagnetic brake that applies each measured value to this calculation formula during actual inspection to easily obtain a predicted value of the braking torque, and preferably evaluates the brake performance based on the lower limit value of the predicted interval.

Background Art

[0002] Currently, the rope type is widely used as a passenger and cargo elevator for various buildings and facilities. In a rope type elevator, a wire rope connecting a car room and a counterweight is wound around a sheave in a pulley type, and an electric hoisting machine is used to efficiently raise and lower by utilizing the frictional force (traction) between the rope and the sheave. In addition, an increasing number of hoisting machines adopt an inverter control method in which the acceleration, deceleration, and stop of the motor are controlled by variable control of the supply power frequency to achieve an energy-saving effect.

[0003] Regular inspections are necessary for any elevator, and many inspection items are set. Among them, the inspection of the brake is important. In a regular inspection, usually, it is confirmed that the amount of change as a decrease in performance with respect to the reference value is within the specified value.

[0004] On the other hand, drum-type and disc-type electromagnetic brakes are widely used in the hoisting machines of current passenger and freight elevators. The drum-type brake performs braking by pressing friction material such as brake pads against the side of a brake drum that rotates with the rotating shaft via a pair of brake arms. The disc-type brake performs braking by clamping and pressing friction material such as brake pads or linings against both sides of a disc-shaped brake disc fixed coaxially with the motor's rotating shaft. In both cases, braking and release operations are performed using the biasing force of a spring and the attractive force of an electromagnetic drive unit that opposes it. In particular, for emergency braking and holding of the equipment, mainly de-excitation type brakes, that is, those that function as brakes when the power is cut off, are used. Compared to the drum-type brake, the disc-type brake is considered more desirable because its moving parts are smaller and it operates faster.

[0005] In the case of a non-excitation type, when energized, the energized movable part is attracted to the fixed part made of a permanent magnet and moves in the release direction against the spring biasing force relative to the brake disc. However, when the energization is cut off and the movable part is in a non-excitation state, the spring biasing force presses the friction material against the brake disc, suppressing its rotation and bringing it to a stop.

[0006] In periodic inspections of such disc-type electromagnetic brakes, not only structural inspections such as checking the thickness of the friction material and determining the amount of wear are performed, but also braking force inspections are considered an important item. In normal operation, the rotation of the sheave is stopped by the rotation control of the motor, and the holding force that maintains this stopped state is the so-called static torque (static friction torque). This static friction torque was measured and used to determine the braking force.

[0007] Conventional inspection methods include, for example, first placing a specified weight on the elevator car while it is stopped with the brakes applied and confirming that the car does not move; then placing a certain load on the car to balance it and measuring the torque value at the motor's rotating shaft using a torque wrench, confirming that the torque value is not lower than the specified torque value; there are also methods of moving the elevator car at a low speed and inspecting the stopping distance when it is suddenly braked; and for electric motors, from a stopped state with the car braked, applying a specified torque value electrically to the motor and confirming that the car does not move. However, none of these conventional methods are accepted under current certification.

[0008] On the other hand, in situations such as emergency stopping of the cage, a braking force must be generated on the motor's rotating shaft to immediately stop the sheave rotation. Therefore, it seems necessary to inspect and evaluate this braking force as part of the brake performance. Although this braking torque is fundamentally different from static friction torque, it has been conventionally believed that braking torque is approximate to static friction torque, so periodic inspections have only required the measurement of static friction torque.

[0009] In recent years, the installation of door-open travel protection devices (UCMPs) has become mandatory for newly installed elevators. These door-open travel protection devices prevent accidents by avoiding situations where the elevator car moves before all the car doors and landing doors are closed due to a malfunction in the elevator's drive unit or control unit. They are equipped with two independent brakes and a separate safety control circuit from the one used for normal operation, and if the car moves beyond a certain distance from the landing with any door open, the hoisting machine motor is immediately stopped.

[0010] In this mechanism, even if one of the two independent brakes fails to provide braking force for any reason, the other brake can still hold the car in place. Furthermore, even if the normal driving control program malfunctions, the UCM control circuit can safely stop the car. In other words, the door-open driving protection device is a device that provides double safety in terms of both brakes and control.

[0011] In periodic inspections of such door-open travel protection devices, the inspection items naturally include checking the braking force of the hoisting machine. One method for this is to run the cage at a low speed for inspection and check the braking distance during braking. In this method, the braking distance is calculated as the distance between the cage position at the time the braking signal is output and the cage position when it actually stops, and a judgment is made after confirming that this braking distance is below a standard value (see, for example, Patent Documents 1 to 3). However, this method has the problem that it does not take into account the slip distance of the rope.

[0012] Furthermore, a method for checking the brake force specified for the inspection of door-open travel protection devices in recent years involves applying motor torque in the upward direction to an unloaded basket with one of the two brakes engaged and the other released, measuring the motor current value at the start of rotation, and then similarly measuring the motor current value with one of the two brakes released and the other engaged. The braking torque is then estimated from these current values. The determination is made by comparing the braking torque during this inspection with the standard value or by checking the amount of change. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 8-108983 [Patent Document 2] Japanese Patent Publication No. 2010-52875 [Patent Document 3] Japanese Patent Publication No. 2018-135197 [Overview of the project] [Problems that the invention aims to solve]

[0014] As described above, in conventional elevator periodic inspections, measuring braking torque using the inertia braking method was rarely used to verify braking force. This is because it is too cumbersome to perform every periodic inspection, and because the moment of inertia differs from site to site, setting up measuring equipment is complicated and prone to human error, making it impractical. Therefore, a simple method for obtaining effective braking force for use in evaluation during periodic inspections had not been established.

[0015] The object of the present invention is to provide a braking force inspection method for disc-type electromagnetic brakes that can determine a predicted braking torque value that allows for evaluation of the actual braking force during inspection, simply by using measured values ​​of each element that affects the brake torque, which can be measured relatively easily without requiring elaborate setup. [Means for solving the problem]

[0016] A method for testing the braking force of a disc-type electromagnetic brake according to claim 1, wherein a braking force is generated on the rotating shaft of a motor by pressing a friction material against a brake disc fixed coaxially with the rotating shaft of the motor using a movable part, The system includes a calculation formula setting step, in which, in advance, a regression equation is set for the disc-type electromagnetic brake installed on the device to be inspected, to be used as a calculation formula to obtain a predicted value of the braking torque at a later inspection. In this equation, braking torque (Nm) is the dependent variable and at least static friction torque (Nm) is the independent variable. The above calculation formula setting step is: Regarding the aforementioned disc-type electromagnetic brake, the braking torque used to stop the rotation of the motor is defined as the actual braking time Tab(s) from the start of braking (when the brake begins to take effect) to the stop when the brake is activated by cutting off the power supply while the motor is rotating, and the actual rotational speed n(min) of the brake shaft at the start of braking. -1 ) and the measured value and the motor shaft equivalent total moment of inertia ΣJ(kg·m) 2A measurement step which involves repeating multiple times the following: a braking torque measurement step which determines the braking torque (Nm) = (ΣJ / 9.55) × (n / Tab) based on the above; and a measurement step which includes measuring the static friction torque at the start of manual rotation with a torque wrench on the motor rotation shaft from at least the stopped state of the motor. The present invention is characterized by comprising a regression analysis step, in which, for all measurements obtained in the above measurement step, a regression analysis is performed between the measured value of the braking torque used as the objective variable and the measured values ​​of one or more explanatory variables, including the static friction torque, to determine the regression coefficients and intercepts of the explanatory variables and obtain the regression equation.

[0017] The braking force testing method for a disc-type electromagnetic brake according to claim 2 is the braking force testing method for a disc-type electromagnetic brake according to claim 1, wherein the explanatory variable is, in addition to the static friction torque, the brake after the measurement of the static friction torque. disk The invention is characterized by including either or all of the temperature of the brake disc, the brake surface temperature of the movable part near the brake disc, and the brake air gap, which is the gap between the brake disc and the friction material as the range of motion of the brake in a fastened state.

[0018] The braking force inspection method for a disc-type electromagnetic brake according to claim 3 is a braking force inspection method for a disc-type electromagnetic brake according to claim 1 or 2, wherein the periodic inspection step is performed as a periodic brake inspection following the usage period after a target device equipped with a disc-type electromagnetic brake of the same type as the disc-type electromagnetic brake for which the calculation formula has been set in advance has been installed at a place of use, An inspection measurement step that includes measuring the explanatory variables, which at least includes measuring the static friction torque when the motor rotation is started manually with a torque wrench from a stopped state of the motor, A calculation step of predicting braking torque by applying measured values ​​of explanatory variables, including at least the static friction torque, to a predetermined calculation formula, A determination step of determining the braking performance based on the braking torque predicted in the calculation step and a predetermined reference value, characterized by comprising the same.

[0019] The braking force inspection method for a disc type electromagnetic brake according to the invention of claim 4 is the braking force inspection method for a disc type electromagnetic brake according to claim 3, wherein when the device to be inspected is a hoist for a rope type elevator and includes two of the disc type electromagnetic brakes independent of each other, The calculation formula setting step measures the respective braking torques for the two Disc-type electromagnetic brake and sets the calculation formula, the two Disc-type electromagnetic brake The regular inspection step, which is a regular brake inspection performed as the usage progresses after a hoist equipped with two Disc-type electromagnetic brake of the same type is installed in an elevator, performs the inspection actual measurement step for each of the two Disc-type electromagnetic brake , The calculation step predicts the braking torque of each of the two Disc-type electromagnetic brake by applying the measurement values obtained in the inspection actual measurement step performed for each of the two Disc-type electromagnetic brake to the calculation formula, characterized by the above.

[0020] The braking force inspection method for a disc type electromagnetic brake according to the invention of claim 5 is the braking force inspection method for a disc type electromagnetic brake according to claim 4, wherein the calculation formula setting step includes a prediction interval calculation formula setting step of setting a prediction interval upper limit value (or lower limit value) Nm = predicted value + (or -) reliability coefficient × standard error × prediction error, which is a prediction interval calculation formula for obtaining the upper limit value and the lower limit value of the prediction interval of the predicted value of the braking torque from the reliability coefficient, standard error, and prediction error obtained by the regression analysis, The determination step is characterized by using the upper limit value and the lower limit value of the prediction interval obtained by applying the predicted value of the braking torque to the prediction interval calculation formula for the determination of the braking performance.

Advantages of the Invention

[0021] As described above, the present invention provides a method for testing the braking force of a disc-type electromagnetic brake. By simply applying measured values ​​of one or more elements affecting braking torque, including at least static friction torque, which can be measured relatively easily during the actual test, a calculation formula is pre-set that can accurately predict the braking torque equivalent to the actual brake force. Therefore, in testing brake force, the brake performance can be easily determined based on this predicted value without the need for elaborate setups or complicated equipment. Furthermore, safety can be ensured by obtaining a predicted interval based on the predicted value of the brake and adopting its lower limit for determining brake performance. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic partial diagram of a hoisting machine used for testing the braking force of a disc-type electromagnetic brake according to the present invention, and is an explanatory diagram showing the inspection shaft for measuring static friction torque. [Figure 2] This is a simple linear scatter plot showing the results of a demonstration test in an embodiment of the present invention (horizontal axis: static friction torque Nm, vertical axis: braking torque Nm). [Modes for carrying out the invention]

[0023] The present invention includes a calculation formula setting step, which involves setting a regression equation in advance for a disc-type electromagnetic brake installed in a device to be inspected, as a calculation formula to obtain a predicted value of the braking torque at a later inspection. In this regression equation, braking torque (Nm) is the dependent variable and at least static friction torque (Nm) is the independent variable. The calculation formula setting step involves setting a regression equation for the disc-type electromagnetic brake as the braking torque that stops the rotation of the motor, using the actual braking time Tab(s) from the start of braking when the brake begins to take effect when the brake is activated by cutting off the power supply while the motor is rotating, to the point where it stops, and the actual rotational speed n(min) of the brake shaft at the start of braking as the braking torque. -1 ) and the measured value and the motor shaft equivalent total moment of inertia ΣJ(kg·m) 2The system comprises: a braking torque measurement step of determining the braking torque (Nm) = (ΣJ / 9.55) × (n / Tab) based on the above; a measurement step of explanatory variables which includes measuring the static friction torque at the start of manual rotation with a torque wrench from at least the stopped state of the motor; a measurement step which repeats the above multiple times; and a regression analysis step which determines the regression coefficient and intercept of the explanatory variables by performing a regression analysis on all the measured values ​​obtained in the measurement step between the measured value of the braking torque, which is the objective variable, and the measured values ​​of one or more explanatory variables, including the static friction torque, to obtain the regression equation.

[0024] The present invention was conceived when the inventors first focused on the correlation between braking torque and static friction torque, and after various studies, as shown in the embodiments described later, they discovered for the first time that a regression equation obtained by regression analysis with braking torque as the dependent variable and at least static friction torque as the independent variable for a disc-type electromagnetic brake under inspection could be set as a calculation formula that can accurately predict braking torque. Furthermore, it was confirmed that a regression equation obtained by multiple regression analysis, in addition to static friction torque, with a combination of the temperature of the brake disc after measurement of static friction torque or the brake surface temperature at the movable part near the brake disc and the brake air gap, which is the gap between the brake disc and the friction material as the range of motion of the brake in the fastened state, can be set as a calculation formula that can accurately predict braking torque.

[0025] Therefore, with respect to disc-type electromagnetic brakes installed in drive devices such as elevator hoisting machines, for example, by setting up a calculation formula that can predict the braking force of the disc-type electromagnetic brake in advance, according to the calculation formula setting process described above, before the sale and shipment of the device, the braking torque can be predicted with high accuracy during periodic inspections that occur after the installation and use of a device equipped with a disc-type electromagnetic brake of the same type as the brake in question. This is achieved by applying a relatively easy-to-measure measurement of static friction torque to this calculation formula, or by applying the measurement values ​​of static friction torque and other explanatory variables. Based on this predicted braking torque, the brake performance can be easily determined. In this way, the pre-set calculation formula can be used in common for disc-type electromagnetic brakes of the same type.

[0026] Furthermore, the moment of inertia J used when measuring the braking torque in the computer setting process of the present invention may be the sum of the moments of inertia of the devices. In the case of a hoisting machine installed in an elevator, the efficiency of the elevator should be taken into consideration. In addition, the actual rotational speed and actual braking time can be measured, for example, by attaching a voltage-type tachometer such as a tachogenerator to the motor shaft end directly connected to the brake shaft and observing the brake voltage signal with an oscilloscope such as a memory recorder.

[0027] Furthermore, multiple regression analysis can be performed using various existing calculation software, such as the "Regression Analysis" tool in Microsoft's spreadsheet software Excel (registered trademark) and the general-purpose design software "R". In regression analysis using these software programs, not only the regression equation with respect to the intercept and each regression coefficient is output, but also various analytical values ​​such as corrected R2 (adjusted coefficient of determination) and standard error are output as regression analysis results. In multiple regression analysis, the value of corrected R2 indicates whether it is appropriate to use the elements of the explanatory variables to calculate the dependent variable (how well they fit), and generally, a value of 0.5 or higher is considered to be a valid model. Also, if the p-value of an explanatory variable is less than 0.1%, the null hypothesis "the regression coefficient in each population is 0 (in this invention, each regression coefficient happens to affect the braking torque)" is rejected, and the significance of that explanatory variable is shown. Therefore, the validity of the obtained regression equation as a calculation formula for accurately predicting the braking torque during inspection can be confirmed by using the value of corrected R2 and the p-value obtained during the regression analysis as a guide.

[0028] In the present invention, the regression equation obtained by the multiple regression analysis of the measured values ​​obtained by the above-described computer setting step has been confirmed to be highly accurate, as will be described later, and can be used as a calculation formula to predict the braking torque for confirming and determining the braking force in periodic brake inspections that accompany the usage process after the target device has been installed at the place of use.

[0029] As part of the periodic inspection process to confirm the braking force of the brakes, first, in the actual measurement process for inspection, the static friction torque is measured when the motor starts rotating manually using a torque wrench for inspection readings, starting from a stopped state of the motor. In addition, if the calculation formula (regression formula) set in advance in the calculation formula setting process for use in predicting the braking torque has other elements combined as explanatory variables in addition to static friction torque, then measurements are performed for each element accordingly. For example, the brake surface temperature of the brake disc or the movable part near it, and the brake air gap, which is the gap between the brake disc and the friction material as the range of motion of the brake in the fastened state, are measured. Then, in the calculation process, the measured values ​​of static friction torque, or static friction torque and brake surface temperature and / or brake gap, are applied to the pre-set calculation formula to obtain a predicted value of the braking torque. In the judgment process, the brake performance can be judged based on this predicted value of braking torque.

[0030] Normally, brake force is judged by comparing the braking torque during inspection with a predetermined reference value, or by checking the change from the reference value to determine whether it passes or fails. Therefore, in the present invention, the braking torque obtained by applying the static friction torque measured during inspection, or elements that are used as explanatory variables in combination with the static friction torque, such as the measured values ​​of brake surface temperature and brake air gap, to the calculation formula set in advance as described above, can be used for judgment. Regardless of the measured values ​​of other elements, it is first confirmed that the measured value of static friction torque is above a predetermined level value that indicates the possibility of brake malfunction. If it does not exceed this level value, it can be determined that there is a possibility of brake malfunction and action can be taken immediately.

[0031] However, since the braking torque obtained by the above calculation formula is a predicted value, it is desirable to allow for a range in the predicted value to account for errors in actual inspection and judgment. That is, safety can be ensured by estimating a prediction interval (upper and lower limits) based on the predicted value and adopting at least the lower limit for judgment. The prediction interval can be calculated using the formula: Prediction interval lower limit (or upper limit) = Predicted value - (or +) Reliability coefficient (coefficient in sample size) × Standard error × Prediction error, but this is usually calculated using analysis software used in regression analysis. That is, these reliability coefficients, standard errors, and prediction errors are calculated during the regression analysis when obtaining the calculation formula (regression equation), and the prediction interval can also be obtained at the same time.

[0032] The braking force testing method for disc-type electromagnetic brakes of the present invention is widely applicable to drive systems equipped with disc-type electromagnetic brakes. For example, a specific object of inspection is a disc-type electromagnetic brake that applies braking force to the motor of a hoisting machine for a rope-type elevator. In particular, it is effective when dealing with two independently installed brakes (double brakes) in elevator hoisting machines equipped with door-open running protection devices of recent years.

[0033] In this case, the calculation formula setting step, which is performed in advance, involves measuring the braking torque for each of the two brakes and setting the calculation formula. Then, in the periodic inspection step, which is performed as a periodic brake inspection following the usage period after the elevator hoisting machine equipped with the same type of double brake as the one for which the calculation formula has been set in advance is actually installed in the elevator, the inspection measurement step is performed for each of the two brakes. That is, the calculation step determines the braking torque for each of the two brakes by applying the measured values ​​obtained in the inspection measurement step performed for each of the two brakes to the calculation formula. In the determination step, a determination can be made by comparing the braking torque of each brake obtained in the calculation step with a reference value for each brake, or by checking whether the amount of change from the reference value is within a predetermined specified amount. At this time, it is desirable to use the predicted interval estimated based on the predicted value. [Examples]

[0034] The following describes the process by which we established the calculation formula according to the present invention, which can predict braking torque with high accuracy during inspection.

[0035] -Conventional method comparison test: Calculation of static friction torque based on motor current value- First, a conventional comparative test was conducted using an inverter-controlled hoisting machine for a rope-type elevator equipped with a door-open travel protection device as the test device to verify its practicality. Specifically, in a double brake system in which two non-excitation-operated electromagnetic brakes are arranged for the upper and lower brake discs on the same axis and each generates braking force individually, torque was applied to the motor in the upward direction with one brake at a time, i.e., with one brake released and the other brake engaged. The motor current value at the start of rotation was measured using the inverter current value to estimate the braking torque.

[0036] The specifications of the test equipment are as follows: The hoisting machine (CDH50 type) is for a 5-ton load (compatible with loading C2), has a reduction ratio of 1 / 38.5, a sheave diameter of 660 mm, and a brake shaft moment of inertia of 0.84 kg / m. 2 The motor is an IE3 manufactured by Fuji Electric Co., Ltd., with a capacity of 30kW 4P, a rated torque of 194Nm, a rated current of 115A, and a torque constant of 1.68Nm / A. The brake is a 08 type manufactured by KEB Japan Co., Ltd., with a braking torque of 150Nm~300Nm. The inverter is a G7-37kW manufactured by Yaskawa Electric Corporation. The specifications of the test elevator are: lifting / lowering distance 12.2m, CW (counterweight) 50% (shaft unbalance torque 88Nm), lost torque: [(no-load upward current 50A - no-load processing current 107A) × torque constant 194Nm / A]÷2 = -43.6Nm.

[0037] Under the above conditions, the torque constant to be checked was set as follows: braking torque (one side of brake) 150 Nm - (unbalanced torque 88 Nm - lost torque 43.6 Nm) = 105.6 Nm, and the current value to be checked was set as follows: 105.6 Nm ÷ 1.68 Nm / A = 62.9 A. The brakes were tested four times each on one side during an unloaded ascent at a cage speed of 1 m / min.

[0038] Table 1 shows the motor current value (A) measured for each brake (upper and lower) during rotation 4 seconds after startup, and Table 2 shows the static friction torque (Nm) obtained using the torque constants shown from each current value.

[0039] [Table 1]

[0040] [Table 2]

[0041] The results in Tables 1 and 2 show that the average values ​​of the measured current and torque differ between the upper and lower brakes. This is likely due to the difference in brake stroke between the upper and lower brakes, resulting in differences in spring pressure, as well as the difference in brake disc temperature during the test. In this test, the upper brake was tested first, so the brake disc temperature was higher during the lower brake test than during the upper brake test. This is because brakes have a characteristic where the coefficient of friction increases proportionally with temperature up to 100°C. In actual hoisting machines, the brake strokes of the upper and lower brakes are made to match.

[0042] Based on the several problems observed in the above control tests, it was found that this conventional method is not practical for verifying brake force during periodic elevator inspections. The problems include, firstly, the need to short-circuit a portion of the safety control (UCMP) circuit before the test, which increases the risk of human error when performed during periodic inspections. Secondly, a characteristic of this type of brake is that rotating the motor with the brake closed causes a rapid increase in the friction coefficient due to temperature rise and frictional friction, potentially damaging the brake lining and other friction materials. Furthermore, in this test, the braking torque was estimated using the motor's torque constant while monitoring the inverter's current value; however, the displayed current value was rounded using a moving average method performed within the measuring instrument, and in reality, the current fluctuated significantly in 10 msec increments. Since static friction torque is greater than braking torque, a large current is required to initiate movement, and even after movement, it takes a certain amount of time for the current to stabilize. Whether this stabilization time falls within 2-3 seconds is difficult to determine due to variations between individual brakes.

[0043] Furthermore, a similar test was conducted on another hoisting machine (CDH35 type, 3.5 ton capacity, sheave diameter 660 mm, brake shaft moment of inertia 0.275 kg / m). 2 In addition, the same type of brake (KEB Japan Co., Ltd. 08 model, braking torque 150Nm~300Nm), with a motor (Hitachi Industrial Systems Co., Ltd. 18.5kw, rated current 70A, rated torque 119.4Nm, torque constant 1.7Nm / A, inverter (Hitachi Industrial Systems Co., Ltd. SJ700-22kw) was tested multiple times, but the same problems as above occurred, and the current was unstable, making it impossible to acquire data. Furthermore, smoke was generated due to the temperature rise of the brake disc after several attempts.

[0044] For the reasons stated above, it is questionable whether the current value itself can be accurately measured using this conventional method, and it is difficult to say that it is appropriate to confirm and evaluate brake force based on this current value during periodic inspections.

[0045] Therefore, the inventors considered the possibility of quantifying the relationship between static friction torque and braking torque as a function, given that in the field of elevator hoisting machines, it had been empirically believed that braking (dynamic friction) torque is correlated with static friction torque. Specifically, by performing regression analysis with braking torque as the dependent variable and static friction torque as the independent variable, if a highly accurate regression equation can be obtained, then during actual periodic inspections and other brake performance evaluations, the relatively easy-to-measure value of static friction torque can be applied to this regression equation to obtain a predicted value of braking torque that can be used for evaluation. Furthermore, by combining static friction torque with other factors that affect braking torque as independent variables, it may be possible to obtain a regression equation that can predict braking torque with even higher accuracy. Therefore, braking torque and static friction torque were measured, and other independent variables were also examined in the following demonstration tests.

[0046] - Demonstration Test - First, using the inverter-controlled elevator hoisting machine 1 shown in the partial diagram of Figure 1, a double brake (upper brake 10, lower brake 20) of the same type as in the above-mentioned control test (KEB Japan Co., Ltd. Model 08, braking torque 150Nm~300Nm) was used. The braking (dynamic friction) torque and static friction torque were measured for each brake, and a regression analysis using the measurement data was performed to confirm the correlation between the two, as described below. In addition to static friction torque, other factors that could serve as explanatory variables were also measured, and multiple regression analysis was performed. Since braking torque is directly affected by the friction surface shape (coefficient of friction) of the friction material (brake pad) and the pressing force (spring load, etc.), regression analysis was performed by measuring the brake disc temperature immediately after braking torque measurement, which indirectly affects the friction coefficient of the brake pad, or the brake surface temperature of the movable part that presses the brake pad against the brake disc in the vicinity of that temperature, and the range of motion of the brake in a fastened state: the brake air gap, which is the gap between the brake disc and the brake pad, and which is directly related to the pressing force, as explanatory variables that affect braking torque.

[0047] The test equipment specifications are as follows. The hoisting machine used was the CDH35 type (3.5 ton capacity) used in the aforementioned control test. The motor was an 18.5 kW motor manufactured by Hitachi Industrial Systems Co., Ltd., and the inverter was an SJ700 manufactured by Hitachi Industrial Systems Co., Ltd. Braking torque was measured using the inertia braking method. As shown in Figure 1, a voltage-type tachometer (7V / 1000 rpm output manufactured by Hitachi Industrial Systems Co., Ltd.) was attached to the shaft end 30 of the motor 3, which is directly connected to the brake shaft 2 of the hoisting machine, and an oscilloscope (HIOKI-MR8870 memory recorder manufactured by HIOKI E.E. CORPORATION) was set up to record the brake voltage.

[0048] In the above setup, one of the two brakes is kept engaged, while the other is mechanically or electrically released. The brake is then activated by cutting off the power supply while the motor is rotating, while monitoring the brake voltage and brake shaft rotation speed with an oscilloscope. The oscilloscope shows that the brake voltage decreases after free-running, the actual brake torque rises, and the brake begins to engage, as confirmed by the waveform indicating a decrease in the brake shaft rotation speed. The time from the start of actual braking to a complete stop is measured as the actual braking time. The actual rotation speed of the brake shaft at the start of braking is also measured simultaneously. These measured values ​​and the mechanical design value of the moment of inertia are applied to the braking torque calculation formula to determine the braking torque (Nm).

[0049] Next, while keeping the other brake in the released state, the static friction torque of one brake was measured at the start of movement using a test reading torque wrench (DBE560N, manufactured by Higashi Nippon Seisakusho Co., Ltd.) attached to the motor shaft end for brake torque measurement. Immediately after measuring the static friction torque, the brake disc temperature, the brake surface temperature in its vicinity, and the surface temperature of the movable part that presses the brake pad against the brake disc were measured using a contact thermometer. The brake air gap of each brake was measured at three points on the brake disc at equal angular intervals of 120 degrees using a feeler gauge, and the average value of these measurements was taken as the measured value. The results of the tests performed in the above measurement process are summarized in Table 3.

[0050] [Table 3]

[0051] As summarized in Table 3, in this demonstration test, the measurement process for the upper and lower brakes was repeated 30 or 40 times in each test, and this was done in 9 tests (Test 1 to Test 9), for a total of 604 measurement processes. Here, the disclosure of all measurement data is omitted, and Table 3 shows the average values ​​of the braking torque and each explanatory variable for the upper and lower brakes for each of Tests 1 to 9.

[0052] First, a simple linear regression analysis was performed in Excel using the measurement data from the above tests, with braking torque as the dependent variable and static friction torque as the independent variable. The analysis results are shown in Table 4. A scatter plot of the simple linear regression is shown in Figure 2. Figure 2 also shows the regression line determined by the intercept and regression coefficients from the regression analysis.

[0053] [Table 4]

[0054] The above simple regression analysis yielded a regression coefficient of 0.2684 for static friction torque and an intercept of 194.93, resulting in the regression equation Y(Nm) = 0.2684X1 + 194.93(Nm), where X1 = static friction torque value (Nm). Furthermore, the adjusted R² value, which represents the adjusted coefficient of determination shown in Table 4, is 0.61, a value greater than 0.5 and closer to 1, indicating a good fit for the explanatory variables in this regression equation. In other words, the analytical model that uses static friction torque as an explanatory variable and returns braking torque as an dependent variable is sufficiently valid, and it was confirmed that the predicted braking torque obtained from measured static friction torque can be used for brake performance evaluation using this regression equation.

[0055] Next, considering the case where the brake air gap, which is thought to be a factor influencing braking torque, is combined with the static friction torque, the first explanatory variable, as the second explanatory variable, multiple regression analysis was performed in Excel using the measured values ​​of the two explanatory variables, static friction torque and brake air gap, against the measured value of the braking torque, which is the dependent variable, from the above measurement data. The results are shown in Table 5.

[0056] Table 5 shows the results of the multiple regression analysis. The regression coefficient for static friction torque is 0.2437, the regression coefficient for brake air gap is -48.07, and the intercept is 228.1. Therefore, the regression equation Y(Nm) = 0.2437X1 - 48.07X2 + 228.1(Nm), (X1 = static friction torque value (Nm), X2 = brake air gap value (mm)) was obtained. The corrected R2 shown in the regression statistics in Table 5 was 0.68, which is a value closer to 1 (greater than 0.5). This indicates that the explanatory variables in this regression equation fit well, and the analytical model that uses the combination of two explanatory variables, static friction torque and brake air gap, to return the dependent variable, braking torque, is sufficiently valid. Moreover, the significance was confirmed as the P-values ​​for the two explanatory variables were less than 0.1%. Thus, it was confirmed that the predicted value of braking torque obtained from the measured values ​​of static friction torque and brake air gap can be used for brake performance evaluation using this regression equation.

[0057] [Table 5]

[0058] Furthermore, we investigated brake disc temperature and the brake surface temperature, which is a moving part in the vicinity of the disc, as factors that can affect braking torque. Based on the measurement data obtained in this test, we confirmed the correlation between brake disc temperature and brake surface temperature, and as can be seen from the correlation coefficient in Table 6, the correlation coefficient was approximately 0.99. This indicates that only one of them is needed as an explanatory variable. This reduces the number of objects to be measured during inspection, improving the ease of inspection work and efficiency by reducing the time required. Therefore, brake surface temperature, which is easier to measure, was chosen as a candidate explanatory variable.

[0059] [Table 6]

[0060] Generally, the coefficient of friction increases proportionally with temperature up to a certain value; therefore, brake temperature, measured as brake surface temperature, is considered a reasonable explanatory variable for influencing braking torque. Thus, a one-way analysis of variance was performed using brake surface temperature measurement data to determine whether brake temperature affects braking torque. Because the measured temperature during the test ranged from 20 to 30 degrees Celsius, this study was conducted by dividing the data into five groups (G1, G2, G3, G4, G5) as shown in Table 7. The results of the analysis of variance are shown in Table 8.

[0061] [Table 7]

[0062] [Table 8]

[0063] The results of the above analysis of variance showed that brake temperature almost certainly affects braking torque. However, no regularity was found between braking torque and brake temperature, and simple linear regression revealed that there was no homogeneity of variances, meaning that the estimation model did not hold when brake temperature was used as the explanatory variable alone.

[0064] Based on the above, a multiple regression analysis was performed using the 604 measurement data summarized in Table 3, with braking (dynamic friction) torque as the dependent variable and static friction torque, brake surface temperature, and brake air gap as independent variables. The results of the analysis are shown in Table 9.

[0065] [Table 9]

[0066] As a result of the above analysis, the regression coefficient for static friction torque was 0.26, the regression coefficient for brake surface temperature was -0.16, the regression coefficient for brake air gap was -50.6, and the intercept was 230. Therefore, the regression equation for braking torque Y(Nm) was obtained as follows: (X1 = static friction torque value (Nm), X2 = brake surface temperature value (°C), X3 = brake air gap value (mm)).

[0067] The adjusted R² (coefficient of determination after adjustment for degrees of freedom) of the regression statistics is 0.7, which is greater than 0.5 and closer to 1, indicating a good fit of the explanatory variables in this regression equation. In other words, the analytical model that returns the dependent variable braking torque using three explanatory variables—static friction torque, brake surface temperature, and brake air gap—is sufficiently valid. Furthermore, the significance of these variables was also confirmed, as the P-values ​​for the three explanatory variables are less than 0.1%. Specifically, the conclusions drawn from this regression equation are that "a 1 Nm increase in static friction torque increases braking torque by 0.26 Nm (significant)", "a 1°C increase in brake surface temperature decreases braking torque by 0.16 Nm (significant)", and "a 0.1 mm increase in brake air gap decreases braking torque by 5.06 Nm (significant)".

[0068] Therefore, this regression equation allows for the prediction of the braking torque at a given time with a certain degree of accuracy by applying measured values ​​of static friction torque, brake surface temperature, and brake air gap for the same type of disc-type electromagnetic brake. Consequently, this regression equation can be used as a calculation formula for predicting braking torque for determining brake force in actual periodic inspections.

[0069] - Brake force testing of elevator hoisting machines using regression equations - As described above, an example of brake force testing for identical disc-type electromagnetic brakes in an elevator hoisting machine is shown below, using the test calculation formula (regression formula) set by the three set variables. Here, we show the case where the hoisting machine is the same type as in Verification Test 2, CDH35 model, and the same type of double brake (08 model manufactured by KEB Japan Co., Ltd.) is being tested. The test procedure is the same as the measurement process for static friction torque, brake surface temperature, and brake air gap that was used to determine the regression formula.

[0070] First, the elevator is set to either condition 1 (loading weights into the car and maintaining a balance with the counterweight while considering the difference in rope weight. To confirm the equilibrium balance, the motor current value during ascent and descent is measured and adjusted so that the difference is zero. At this time, the lost torque is calculated) or condition 2 (with no load, the counterweight load is placed in the pit, and the load transmitted to the sheave is made zero).

[0071] Next, with one of the double brakes held in the engaged position and the other electrically or mechanically released, the static friction torque X1 is measured using a test-readable torque wrench at the motor shaft end, which is coaxial with the brake shaft. Then, the brake surface temperature X2 near the brake disc is measured. In addition, the gap between the brake disc and the friction material, which is the brake air gap X3 representing the range of motion in the engaged brake state, is measured using a feeler gauge. The measurement is taken at three locations on the brake disc at equal angular intervals of 120 degrees, and the average value of these measurements is taken as the measurement value. The above measurement process is performed for both the upper and lower brakes.

[0072] The measured values ​​X1, X2, and X3 obtained above are applied to the predetermined calculation formula (regression formula) for this type of brake: Braking torque Y (Nm) = 0.26 × X1 (static friction torque Nm) - 0.16 × X2 (brake surface temperature °C) - 50.6 × X3 (brake air gap mm) + 230 to obtain a predicted value of braking torque Y. The prediction interval is then calculated to obtain the lower limit. Measurement examples 1 for the upper brake and 2 for the lower brake are shown below.

[0073] In measurement example 1, when X1=245, X2=24.4, and X3=0.8, the predicted braking torque Y=245.73 (Nm), and the lower limit of the prediction interval was 219.98 (Nm). In measurement example 2, when X1=265, X2=23.1, and X3=0.6, the predicted braking torque Y=264.32 (Nm), and the lower limit of the prediction interval was 235.69. These lower limits can be used as the braking torque for determination.

[0074] Furthermore, although the above inspection process will be performed each time a periodic inspection is conducted, the inspection work itself does not require elaborate environmental setups or complicated equipment. It only involves relatively simple measurement processes such as measuring static friction torque, brake surface temperature, and brake air gap. Therefore, it is a method that reduces the burden on the inspector and takes less time, while still allowing for brake force testing with higher accuracy than conventional methods. [Industrial applicability]

[0075] Although the above embodiments have described the brakes of an elevator hoisting machine, the brake force testing method according to the present invention is broadly applicable to drive devices equipped with disc-type electromagnetic brakes. Examples include automobiles, motorcycles, and railway vehicles. [Explanation of Symbols]

[0076] 1: Elevator hoisting machine 2: Brake shaft 3: Motor 10: Upper brake 20: Lower brake 30: End of motor shaft

Claims

1. In a method for testing the braking force of a disc-type electromagnetic brake, which generates a braking force on the rotating shaft of a motor by pressing a friction material against a brake disc fixed coaxially with the rotating shaft of the motor using a movable part, The system includes a calculation formula setting step, in which, for a disc-type electromagnetic brake installed on the device to be inspected, a regression equation is set in which braking torque (Nm) is the dependent variable and at least static friction torque (Nm) is the independent variable, as a calculation formula to obtain a predicted value of the braking torque at a later inspection. The above calculation formula setting step is: Regarding the disc-type electromagnetic brake, the braking torque used to stop the rotation of the motor is defined as the actual braking time Tab(s) from the start of braking (when the brake begins to take effect) to the stop when the brake is activated by cutting off the power supply while the motor is rotating, and the actual rotational speed n(min) of the brake shaft at the start of braking. －１ ) and the measured value and the motor shaft equivalent total moment of inertia ΣJ (kg・m ２ A measurement step which includes a braking torque measurement step which determines the braking torque (Nm) = (ΣJ / 9.55) × (n / Tab) based on the above, and a measurement step which includes measuring the explanatory variable, which includes measuring the static friction torque at the start of manual rotation with a torque wrench on the motor rotation shaft from at least the stopped state of the motor, and repeating this multiple times, A method for testing the braking force of a disc-type electromagnetic brake, comprising: a regression analysis step in which, for all measurements obtained by the measurement step described above, a regression analysis is performed between the measured value of the braking torque used as the objective variable and the measured values ​​of one or more explanatory variables, including the static friction torque, to determine the regression coefficient and intercept of the explanatory variables and obtain the regression equation.

2. The method for testing the braking force of a disc-type electromagnetic brake according to claim 1, characterized in that the explanatory variables include, in addition to the static friction torque, the temperature of the brake disc after the measurement of the static friction torque or the brake surface temperature of the movable part near the brake disc, and the brake air gap, which is the gap between the brake disc and the friction material as the range of motion of the brake in a fastened state, or all of these.

3. A periodic inspection process is performed as a brake periodic inspection following the usage period after a target device equipped with a disc-type electromagnetic brake of the same type as the disc-type electromagnetic brake for which the calculation formula has been set in advance has been installed at the place of use, An inspection measurement step that includes measuring the explanatory variables, which at least includes measuring the static friction torque when the motor rotation is started manually with a torque wrench from a stopped state of the motor, A calculation step of predicting braking torque by applying measured values ​​of explanatory variables, including at least the static friction torque, to a predetermined calculation formula, A method for testing the braking force of a disc-type electromagnetic brake according to claim 1 or 2, comprising a determination step of determining the brake performance based on the braking torque predicted in the calculation step and a predetermined reference value.

4. When the device to be inspected is a hoisting machine for a rope elevator and is equipped with two independent disc-type electromagnetic brakes, The calculation formula setting step involves measuring the braking torque for each of the two disc-type electromagnetic brakes and setting the calculation formula accordingly. The periodic inspection process, which is performed as a periodic brake inspection following the usage period after a hoisting machine equipped with two disc-type electromagnetic brakes of the same type as the two disc-type electromagnetic brakes mentioned above is installed in an elevator, involves performing the inspection measurement process for each of the two disc-type electromagnetic brakes. The method for testing the braking force of a disc-type electromagnetic brake according to claim 3, characterized in that the calculation step predicts the braking torque of each of the two disc-type electromagnetic brakes by applying the measured values ​​obtained in the inspection measurement step performed on each of the two disc-type electromagnetic brakes to the calculation formula.

5. The calculation formula setting step includes setting a prediction interval calculation formula, which is a prediction interval calculation formula for obtaining the upper and lower limits of the prediction interval of the predicted value of the braking torque from the reliability coefficient, standard error, and prediction error obtained by the regression analysis, namely, prediction interval lower limit (or upper limit) Nm = predicted value - (or +) reliability coefficient × standard error × prediction error. The method for testing the braking force of a disc-type electromagnetic brake according to claim 4, characterized in that the determination step uses at least the lower limit of the predicted interval obtained by applying the predicted value of the braking torque to the predicted interval calculation formula for determining the brake performance.

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