Drive unit for machinery, especially mining machinery

Details Drive unit for machinery, especially mining machinery Drive unit for machinery, especially mining machinery

1999-03-23

2001-07-31

Bonck, Rodney H. (Department: 3681)

192 clutches and power-stop control

Vortex-flow drive and clutch

With brake

C192S01200R

Reexamination Certificate

active

06267211

ABSTRACT:

FIELD OF THE INVENTION
Our present invention relates to a drive unit for machinery, especially mining machinery, such as mining excavators and conveyor apparatus, wherein a drive motor, a turbocoupling, fluid coupling, hydrodynamic coupling, hydraulic coupling, and a transmission are connected in a drive train to operate the machine. The term “turbocoupling” is here used to describe a fluid coupling, hydrodynamic coupling or hydraulic coupling, also known as a Voith coupling, of the type having an impeller rotor and a driven rotor and wherein the coupling factor between the impeller or driving member and the driven member is controlled at least in part by the hydraulic filling of the fluid coupling. Usually the machinery is an excavator, for example a plow and/or conveyor and the driven element of that machine is a sprocket wheel to which the machine chain is operatively connected.
BACKGROUND OF THE INVENTION
Drive units having a drive train as described, utilizing a turbocoupling, initially should permit the generation of a high speed by the drive motor, for example an electric motor, with the turbocoupling empty. Upon attainment of the nominal speed of the drive motor, the turbocoupling is filled with its liquid medium, for example oil or water, and enables smooth startup and startup under load of the machine.
The control of the degree of filling of the turbocoupling, as has been noted above, affects the delivered torque and thus the operating state of the drive train. However, a hard blockage of the driven part of the system, i.e. the transmission of the driven element which receives the torque from the turbocoupling can cause on the one hand a delay in fuel-torque transmission between the turbine wheel and the pump wheel, i.e. the driven rotor and the impeller rotor of the fluid coupling to compensate for the blockage and, on the other hand, significant dynamic effects on the fly wheel mass forming the turbine rotor which can be detrimental. As a consequence the overload on the turbocoupling must be removed as quickly as possible in the event of such a hard blockage and in practice, load removal by emptying of the fluid coupling can only be done with a certain time delay. This, of course, can be detrimental to the mining machine or conveyor. For example, the chain may break and, in that case, it is important that the drive motor be decoupled rapidly from the transmission so that the run-out of the chain ends does not occur, thereby delaying repair. Furthermore, upon generation of an emergency signal, the mining machine or conveyor must be shut down immediately and that is not possible with conventional designs of the drive unit for such machines.
OBJECTS OF THE INVENTION
It is, therefore, an important object of the present invention to provide a drive unit for the aforedescribed purposes in which, upon hard blockage at the driven side of the drive train, an instantaneous or substantially instantaneous disconnection of the fluid coupling from the transmission and thus of the drive motor from the load can be effected in a reliable, automatic and rapid manner.
Another object of this invention is to provide a drive unit having an electric drive motor, a fluid coupling and a transmission connected in a drive train, for mining machinery such as a mining excavator and/or conveyor, whereby damage to the system in the event of the development of a hard blockage can be avoided and reliable decoupling of the motor from the remainder of the loaded part of the drive train is ensured.
Still another object of the invention is to provide a drive unit for mining machinery and conveyors utilized in mining applications in which drawbacks of earlier systems are avoided.
SUMMARY OF THE INVENTION
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in one embodiment thereof by providing between the turbocoupling and the transmission, a free-shifting clutch. Such a free-shifting clutch functions like an overload clutch and in the case of an overload, provides overload protection in the form of a decoupling of the load from the turbocoupling. Since such a clutch can only engage at standstill, i.e. allow the two clutch halves to couple together again at standstill, according to the present invention, each of the clutch halves has a respective brake disk and a cam disk, the brake disk being engaged between brake jaws acted upon by pneumatic brake cylinders while the cam disks are juxtaposed with electronic speed-monitoring devices or sensors so that the speed-monitoring system and the pneumatic brake wheels are connected by a control and evaluating system, e.g. a microprocessor based electronic controller. In this manner, the operating state of the free-shifting clutch can be continuously monitored.
In the coupled state, the pneumatic brake cylinders are vented and the brake jaws are freed from engagement with the brake disk, while in the decoupled state of the free-shifting clutch, as a consequence of overloading, the brake jaws are actuated by the pneumatic brake cylinders and bring about the standstill of the clutch halves so that the free-shifting clutch can once more engage and serve for the smooth start-up for start-up under load. This presumes a complete filling of the previously completely or partially empty turbocoupling while the drive motor can continue to operate. The free-shifting clutch enables adjustment of the overload and as a result, a selected or targeted load shedding for predetermined operating phases. The speed interrogation of the free-shifting clutch or its clutch halves by means of the speed-monitoring devices or sensors can be provided redundantly.
According to a feature of the invention, between the turbocoupling and the free-shifting clutch, a friction clutch, for example a multiplate clutch can be provided. The friction clutch can be connected with one half to the drive side of the turbocoupling and on the other hand to the driven side of the turbocoupling. The friction clutch enables the transmission of torque from the motor through the turbocoupling without using the hydrodynamic effect thereof to the free-shifting clutch, thereby eliminating slip or lag in torque transmission through the turbocoupling. The friction clutch thus allows the turbocoupling to act as a rigid slip-free connection along the drive track, and it is important that the operation is to utilize, rather than the drive characteristic of the turbocoupling, a drive characteristic of the drive motor so that after reaching operating speed, a multipower drive can be provided in which the slip of the turbocoupling can correspond to an order of magnitude of 4 to 5%. The friction clutch is thus capable of short-circuiting the turbine characteristic so that only the motor characteristic prevails. Alternatively, when that friction clutch is disengaged, the turbocoupling characteristic can prevail. The short-circuiting can be effective especially for the heaviest loaded startup. For such heaviest load startup, the friction clutch is opened, the free shifting clutch is closed and the turbocoupling emptied while the drive motor is operated at its nominal speed. The turbocoupling is then filled.
It will be understood that after complete filling of the turbocoupling, the chain of the mining machine or conveyor may not begin to run although the fuel transmittable torque has been applied by the turbocoupling through the transmission to the sprocket wheel. This case is detected by the sensors at the respective shaft segments. Via a controller, closure of the friction clutch, i.e. the sultiplate clutch, can be effected and in this manner the motor or drive shaft can be rigidly connected with the sprocket wheel shaft in a jerky action so that the fuel torque of the drive motor can be applied to the chain. The chain breaks loose and moves. Following this startup under load, the friction clutch remains closed only until the motor current lies below its nominal current. Upon opening of the friction clutch, load compensation by the turbocoupling commences.
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