JPH0524829Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a maintenance monitoring device for detecting an abnormal brake condition in a load hoisting and lifting device such as a crane.

[Conventional technology]

In equipment that hoists and lowers loads, if there is an abnormality in the brakes (wear of the lining, uneven contact, etc.), abnormal conditions may occur such as the load descending despite the brakes being applied, resulting in accidents, etc. There is a risk that it may lead to For this reason, it is desired to detect brake abnormalities early.

Conventionally, in order to discover this abnormal condition, an operator would periodically visually monitor the wear condition of the lining.

[Problem that the invention attempts to solve]

The visual inspection method has the drawback that it cannot be used in cases where the operator neglects regular inspections or when abnormalities suddenly occur during operation.

This invention solves the problems in the conventional technology and makes it possible to respond to sudden abnormalities without visual inspection by the operator, thereby reliably detecting brake abnormalities. It is an object of the present invention to provide a brake maintenance monitoring device for a load hoisting and lifting device.

[Means for solving problems]

This invention includes a means for measuring the amount of movement or time from when a brake activation command is given to a load hoisting and lifting device or when the brake is actually activated until the movable part stops or almost stops; A means for detecting that a predetermined reference value has been exceeded; a load detecting means for detecting the weight of a load being hoisted and lowered in a suspended state; and, when the weight detected by this load detecting means is large, the above reference value and a reference value control means for increasing the reference value and reducing the reference value when the detected weight is small.

[Effect]

A certain amount of slip occurs from when a brake activation command is given or from when the brake is actually activated until it stops (usually within 2 to 3 seconds), but this amount of slip increases if there is an abnormality in the brake. Therefore, in this invention, the amount of movement or time from when a brake activation command is given or when the brake is actually activated until the movable part stops or almost stops is measured, and this measured value is determined to be abnormal. By detecting that a predetermined reference value has been exceeded, sudden abnormalities can be detected without visual inspection by the operator, and safety can be improved. In addition, since the reference value is varied by detecting the load, it is possible to correctly determine whether it is abnormal or normal, regardless of the magnitude of the load.

〔Example〕

An embodiment of this invention is shown in FIG.

The hoisting and lifting device shown in FIG. 1 uses a motor 10 as a driving source to drive a drum 14 in forward and reverse rotation via a speed reducer 12, and raises and lowers a load 18 by winding a wire 16 around the drum 14. brake 20
is attached to the motor shaft 22. When the brake 20 is in a non-excited state, the brake lining comes into pressure contact with the brake drum due to the biasing force of the spring, inhibiting rotation of the motor 10 and entering the braking state.
In the energized state, the brake lining is pulled away from the brake drum against the biasing force of the spring, allowing the motor 10 to rotate.

A pulse generator, an incremental rotary encoder, or the like is directly connected to the motor shaft 22 as a position detector 24 for detecting the amount of rotation thereof. The position detector 24 generates a number of pulses corresponding to the amount of rotation thereof.

The brake sequence circuit 26 supplies the brake 20 with an excitation current for driving an electromagnet to keep the brake lining separated from the brake drum against the spring during non-braking operations. When a brake activation command is given by an operator, etc.,
This exciting current is cut off, and the brake lining is brought into pressure contact with the brake drum by the action of the spring, thereby applying the brake.

The slip amount counting circuit 28 is for measuring the amount of movement of the motor 10 from when a brake activation command is given until the rotation of the motor 10 completely stops. This slip amount counting circuit 28 is composed of a counter, for example, and is cleared when no brake operation command is given, and becomes enabled when a brake operation command is given, and the rotational position detector 2
Count the pulses output from 4. When the motor 10 completely stops, the rotational position detector 2
Since pulses are no longer output from 4 onwards, counting stops, and the final count value corresponds to the slip amount.

The slip reference amount selection circuit 34 outputs the slip amount at which the brake is determined to be abnormal as a reference value. The comparator 36 receives the slip amount detection signal from the slip amount counting circuit 28 and the slip reference amount selection circuit 3.
4, and if the detection signal exceeds the reference amount, it is determined that there is an abnormality in the brake 20, and an abnormality detection signal is output, and an alarm or the like is issued to notify the abnormality. Based on this, the operator stops the operation and inspects the brake 20.

Note that the amount of slip is 18% even under normal conditions.
It varies depending on the weight as shown in Figure 2. Therefore, if the slip reference amount is set constant, if the load 18 is heavy, there is a possibility that a malfunction such as a slip amount detection signal being issued may occur even if there is no abnormality in the brake 20.

Therefore, in the slip amount selection circuit 34, the slip reference amount is varied in accordance with the weight of the load 18. Here, taking advantage of the fact that the armature current of the motor 10 changes almost linearly depending on the load, a low resistor is inserted as a shunt circuit 32 in the armature current supply line 30, and a slip reference amount selection circuit 34 is inserted into the armature current supply line 30. The load is detected by the amount of voltage drop across the shunt circuit 32, and a slip reference signal corresponding to each load (the greater the load, the greater the slip reference amount) is output. Thereby, even if the load fluctuates, it is possible to detect an abnormality in the brake without malfunction.

[Example of change]

In the embodiment described above, the amount of movement since the brake activation command was issued is detected, but the brake 20
It is also possible to attach a limit switch or the like to the movable part of the brake 20 to detect the amount of movement after actually detecting the operation of the brake 20.

Further, in the embodiment described above, the amount of movement is measured by the rotational position detector 24, but the amount of slip can also be detected by measuring the time from activation to stoppage.

Further, in the above embodiment, the load is detected by armature current, but it can also be detected by attaching a load cell to the shaft of the drum 14.

[Effect of idea]

As explained above, according to this invention, the amount of movement or time from when a brake activation command is given or when the brake is actually activated until the movable part stops or almost stops, and this measured value is abnormal. Since it is detected that the predetermined reference value has been exceeded, abnormalities can be discovered suddenly without visual inspection by the operator, and safety can be improved. In addition, since the reference value is varied by detecting the load, it is possible to correctly determine whether it is abnormal or normal, regardless of the magnitude of the load.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment in which this invention is applied to a hoisting and lifting device such as a crane, and FIG. 2 is a diagram showing the relationship between load and slip amount. 10, 14...Motor, drum (movable part), 2
4...Rotational position detector, 28...Slip amount counting circuit, 32...Shunt circuit (load detection means),
34...Slip reference amount selection means (reference value control means), 36...Comparator.

Claims (1)

[Scope of utility model registration request] means for measuring the amount of movement or time from when a brake activation command is given to a load hoisting/lowering device or when the brake is actually activated until the movable part stops or substantially stops, and the measured value is set to a predetermined reference value. load detection means for detecting the weight of a hoisted load in a suspended state;
A load hoisting and lifting device comprising a reference value control means for increasing the reference value when the weight detected by the load detection means is large and decreasing the reference value when the detected weight is small. Brake maintenance monitoring device.