HK1219088B - Drive train for hoisting gear - Google Patents

Description

Drive train for a lifting device

Technical Field

The invention relates to a drive train for a lifting device, in particular for dangerous transport, comprising a drive motor, a cable drum connected to the drive motor, a retarder arranged between the drive motor and the cable drum, a service brake arranged between the drive motor and the retarder, and a safety brake.

Background

If the lifting device is provided for the transport of hazardous goods, such as molten material or also radioactive material, a safety brake is usually provided in the drive train in addition to the service brake. Safety brakes serving emergency stop braking are normally carried on the axle of the cable drum.

In the case of emergency stop braking in the case of "low" loads, the load direction reverses and therefore a torque shock occurs in the transmission, due to the different application times for the safety brake and the service brake. The torque shock causes excessive loads and stresses in the transmission. The overload and transmission stresses that occur during emergency stop braking are caused in particular by the rotating inertial masses of the motor and of the transmission.

Disclosure of Invention

It is therefore an object of the invention to avoid torque shocks associated with reversal in the direction of the load and the stresses induced thereby in the transmission.

According to the invention, this object is achieved in that an automatic overrunning uncoupling device is provided between the drive motor and the service brake.

These features according to the invention provide that the rotating mass of the electric machine is decoupled from the drive train. Damage to the drive train and in particular to the gear unit is prevented by this decoupling. Furthermore, such a separation will result in a reduction of the stopping distance of the lifting device and the load suspended by the lifting device.

The automatic overrunning decoupling means arranged between the drive motor and the service brake may be an overrunning coupling, preferably in the form of a freewheel.

The free wheels can be designed according to different constructional modes, in which respect they are provided, for example, with clamping rollers, clamping members, toothed discs, coil springs or locking claws. A particularly advantageous freewheel structure suitable for the use according to the invention is a pinch roller freewheel, which not only operates efficiently but also completely noiselessly.

Alternatively, the override disconnect may also be in the form of a releasable coupling which may be switched on electrically in the event of an emergency stop brake. With such a structure, the rotating mass of the motor can also be quickly and efficiently decoupled from the drive train so that the reduction gear does not suffer any damage.

Drawings

The invention is illustrated by way of example in the accompanying drawings and will be described in detail below with reference to the accompanying drawings.

Detailed Description

The drive train for a lifting device according to the invention as shown in the figure comprises a drive motor 1, a freewheel 2, a coupling 3, a service brake 4, a retarder 5, a cable drum 6 and a safety brake 7, the safety brake 7 being specified in particular in relation to transport for hazardous goods. A safety brake 7 is carried on the same shaft 8 as the cable drum 6 and is arranged downstream of the cable drum 6 in the embodiment shown in the figures.

The service brake 4 comprises a brake disc 9, which is enclosed at least on one side by a brake caliper 10 and a corresponding brake pad.

The safety brake 7 further comprises a brake disc 11, which brake disc 11 is enclosed in at least one position by means of a brake caliper 12, which brake caliper 12 is suitably provided with an actuatable brake pad.

In the embodiment shown in the figures both the service brakes 4 and also the safety brakes 7 are designed in the manner of disc brakes.

The freewheel 2 arranged between the drive motor 1 and the coupling 3 is desirably in the form of a noiseless operating pinch roller freewheel.

The coupling 3 arranged between the freewheel 2 and the service brake 4 is in the form of a rigid coupling.

Alternatively, the coupling 3 can also be in the form of an electrically switchable releasable coupling to separate the drive motor 1 from the retarder 5. For that particular case, it would be possible to omit the freewheel 2.

If an emergency stop is triggered when the suspended load is reduced, the service brakes 4 and the safety brakes 7 are closed. As a result of the usual brake-sized safety brake 7, which acts as an emergency stop brake, a shorter application time than the service brake 4 is required. The result is that the rotational movement of the cable drum 6 is stopped before the rotational movement of the retarder input shaft has stopped. Thus, without the measures according to the invention, a percussion torque will occur, which acts in the opposite direction to the actual load direction.

This torque is transmitted through the inertial mass of the drive motor 1, which in a conventional drive train causes a jerky-like reversal in the direction of the torque in transmission. The time course of the reversal in the torque direction occurs at a different application time between the safety brake 7 and the service brake 4.

Thus, in the conventional power train, the inertial mass reacting to the load direction causes the reduction gear 5 tooth side to change from the load side to the opposite side (rearward load side). This will result in shock loads on the opposite side which in conventional drive trains will cause considerable damage to the variator. Such damage of the transmission ranges from light surface damage to tooth flank to tooth breakage, resulting in failure of the transmission.

Such damage can be very effectively avoided by the arrangement according to the invention of automatically overriding the uncoupling device or freewheel 2 in the drive train. It is already the case that, after the response of the safety brake 7 with a very short activation time, the freewheel 2 acts immediately after the stop of the retarder 5, i.e. the torque of the inertial rotating mass of the drive motor is no longer transmitted to the retarder 5 directly connected to the cable drum 6 due to the response of the freewheel 2. The action of the freewheel 2 takes place immediately with the actuation of the safety brake 7 and more particularly still before the service brake 4, which is provided with less action time, comes into engagement.

By the arrangement of the freewheel 2 in the drive train according to the invention, only one torque direction is set, so that in the event of emergency stop braking, no damage occurs to the retarder. The features according to the invention can in turn effectively protect the respective drive train for the lifting device from damage, thereby increasing its service life.

List of reference numerals

1 drive motor

2 free wheel

3 coupler

4 service brake

5 speed reducer

6 cable reel

7 safety brake

8 axle of cable drum 6

9 brake disc of service brake 4

10 brake caliper of service brake 4

11 brake disc of safety brake 7

12 brake caliper of safety brake 7

Claims (4)

1. A drive train for a lifting device, comprising a drive motor (1), a cable drum (6) connected to the drive motor, a retarder (5) arranged between the drive motor (1) and the cable drum (6), a service brake (4) arranged between the drive motor (1) and the retarder (5), a safety brake (7), and an overrunning uncoupling device arranged between the drive motor (1) and the service brake (4), characterized in that the overrunning uncoupling device is arranged between the drive motor (1) and the retarder (5), which overrunning uncoupling device acts immediately with the actuation of the safety brake (7) in a "reduced" load situation and still acts before the service brake (4) provided with less action time comes into engagement.

2. A drive train according to claim 1, wherein the overrunning decoupling means is in the form of an overrunning coupling.

3. A drive train according to claim 2, wherein the overrunning coupling is in the form of a freewheel (2).

4. A drive train according to claim 3, wherein the freewheel (2) is in the form of a pinch roller freewheel.