JPH04361990A - Detecting method for abnormality of braking power in hoist apparatus - Google Patents

Abstract

PURPOSE:To grasp braking force at every braking operation so as to improve safety of a crane by obtaining a total mass amount comprising the speed of suspension tool, the number of revolutions of a motor the weight of a load to be suspended and the like at the start-up of braking operation, while obtaining the moving distance of suspension tool from the start-up of braking operation to stoppage, and comparing the braking force obtained from the total inertia amount and the moving distance. CONSTITUTION:When a stoppage operation is started by working a brake during lowering operation of a hook, a braking equipment finds the inertia amount GD<2> round the shaft of a motor based on the present position of the hook La, the lowering velocity V of the hook at this point of time, the number of revolution of a motor at the same point and the total weight of the hook & a hoisted cargo detected by a load detector, and it calculates the total inertia amount GD<2> in which the inertia amounts of the motor, a brake drum and a hoisting drum was added to the inertia amount G2. When the lowering operation stops, the present position of the hook Lb is found and the moving distance L is determined by the difference between the present positions of the hook La and Lb. The braking force is found by the lowering velocity V, the number of revolution N, the total inertia amount GD<2> and the moving distance L, of suspension tool and it is judged that the brake is good or bad comparing it with the standard value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the wear status of a braking device of a crane hoisting device.

0002

2. Description of the Related Art Conventional means for detecting the wear status of brakes is to operate a limit switch attached to a brake rod when a brake lining has worn down to a predetermined amount.

According to this method, it is possible to detect the absolute amount of wear of the brake lining, but it is not possible to detect abnormalities in the brake due to changes in the wear rate that vary depending on the ambient temperature and the like.

0004

[Problems to be Solved by the Invention] An object of the present invention is to control the braking force of a crane that is frequently operated, which constantly changes depending on the wear condition and temperature rise of the brake lining, the temperature of the brake drum, the adhesion of dirt, etc. The purpose is to detect.

[0005]

[Means for Solving the Problems] The present invention provides brake control by calculating the braking force of the brake from the suspended load mass, the moving speed of the suspended load at the start of braking, and the distance of the suspended load moved during braking. It directly detects a decrease in power.

Braking force T is determined by the mass of the suspended load, the total inertia of rotating bodies such as the drum, electric motor, brake, etc., the speed of movement of the suspended load at the start of braking, the distance until it stops, and the time at the start of braking of the motor. It can be determined by the following formula depending on the rotation speed of .

[0007]

[Math 1]

[0008]

[Math 2]

[0009]

[Math 3]

0010

[Math 4]

[0011] Here, GD2 (kg・m2): Total inertia in terms of motor shaft N (rpm): Motor rotation speed at the start of braking T (kg・m): Braking force v (m/s): Speed L at the start of braking of the suspended load
(m) : Braking distance t until the suspended load stops (sec) : Time from starting braking to stopping

0012

[Operation] From the output of the position detector of the suspended load, it is possible to detect the speed v at the time of starting braking of the suspended load, the braking distance L, and the rotational speed N of the motor at the time of starting braking. The mass of the suspended load can be detected by the load detector and converted into inertia GD2 around the motor drive shaft. Therefore, the braking force T is determined by (Equation 4). If this braking force T is smaller than a predetermined value, it is determined that the braking force of the brake has decreased.

[0013]

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIGS. 3 and 4 show the equipment configuration on a crane club trolley according to an embodiment of the present invention. The suspended load 6 is passed through a rope by a hook 7 and is hoisted up by a hoisting drum 5. The hoisting drum 5 is driven by an electric motor 3 via a reduction gear 4. A brake 1 that generates braking force, which is a target device of the present invention, is attached to a motor shaft. A rotation speed detector 2 is mounted on the same axis as the brake 1. The rotation speed detector 2 is a pulse encoder. A load cell 9 is mounted on the same axis as the hoisting drum 5.

In FIG. 2, a rotation speed detector 2, a load cell 7
The output of is input to the control device 10. The output pulses of the rotation speed detector 2 are constantly counted, and the speed v of the hook 7 and the rotation speed N of the brake drum, that is, the rotation speed N of the motor shaft are calculated from the position of the hook 7 and the amount of change in the count value per unit time. . Further, the amount of inertia GD2 around the motor axis is calculated from the total weight of the hook 7 and the suspended load 6 determined by the load detector 9. The electric motor G
The total GD2 including D2, brake drum GD2, and hoisting drum GD2 is determined as ΣGD2.

In FIG. 1, when the brake 1 is operated during the lowering operation of the hook 7 to start the stop operation, the control device 10 controls the current position La of the hook 7, the lowering speed v of the hook 7 at this point, Similarly, the rotation speed N of the motor 3 and ΣGD2 are determined. (Step S10) When the lowering operation is stopped, the current position Lb of the hook 7 is determined, and
The braking distance L is determined by the difference between a and Lb. (Steps S20, S30) Next, the braking force T is determined using (Equation 4). Then, the braking force T is compared with a reference value to determine whether the brake 1 is good or bad. If the braking force T is larger than the reference value, it is reported that the brake 1 is defective. (Step S
40, S50) According to this, the determination can be made using the rotation speed detector 2 and load detector 9, which are normally provided on the crane. Further, it can be recognized regardless of the weight of the suspended load or the braking start speed.

[0017]

According to the present invention, since the braking force can be grasped for each braking operation, the safety of the crane to which the present device is applied is improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart of an embodiment of the present invention.

FIG. 2 is a block diagram of control according to an embodiment of the present invention.

FIG. 3 is a top view of the trolley.

FIG. 4 is a front view of the trolley.

[Explanation of symbols]

1...brake, 2...rotation speed detector, 3...electric motor, 4...reducer, 5...hoisting drum, 6...hanging load, 7...hook, 9...
Load detection meter.

Claims (1)

[Claims] Claim 1: At the start of braking, the total GD2 consisting of the speed v of the hanging tool, the rotational speed N of the motor, the amount of hanging load, the motor, etc. is determined, and at the time of stopping the movement, the distance L of the lifting tool from the start of braking to the stop is determined. A method for detecting a braking force abnormality in a hoisting device, characterized in that the braking force T is obtained from v, N, total GD2 and L, and the braking force T is compared with a reference value.