Drive arrangement

Abstract

A drive arrangement for driving a work machine includes a motor configured to generate a torque, and a transmission apparatus configured to transmit the torque from the motor to the work machine. The transmission apparatus includes a fluid coupling and at least one controllable torque transmitter configured to control transmission of the torque from the motor to the work machine.

Claims

1. A drive arrangement for driving a work machine, said drive arrangement comprising: a motor configured to generate a torque; and a transmission apparatus configured to transmit the torque from the motor to the work machine, said transmission apparatus including a fluid coupling and at least one controllable torque transmitter configured to control transmission of the torque from the motor to the work machine, wherein the fluid coupling is cooled by load-free driving by the motor.

2. The drive arrangement of claim 1, wherein the at least one torque transmitter comprises at least one coupling selected from the group consisting of autoswitched coupling and externally-switched coupling.

3. The drive arrangement of claim 2, wherein the autoswitched coupling is a free-wheel.

4. The drive arrangement of claim 2, wherein the externally-switched coupling is a multiple-disc coupling.

5. The drive arrangement of claim 1, wherein the at least one torque transmitter is provided in addition to the fluid coupling.

6. The drive arrangement of claim 1, wherein the at least one torque transmitter is arranged between the motor and the fluid coupling.

7. The drive arrangement of claim 1, wherein the at least one torque transmitter is arranged between the fluid coupling and the work machine.

8. A work machine, comprising at least one drive arrangement which includes a motor configured to generate a torque, and a transmission apparatus configured to transmit the torque from the motor to the work machine, said transmission apparatus including a fluid coupling and at least one controllable torque transmitter configured to control transmission of the torque from the motor to the work machine, wherein the fluid coupling is cooled by load-free driving by the motor.

9. The work machine of claim 8, wherein the at least one torque transmitter comprises at least one coupling selected from the group consisting of autoswitched coupling and externally-switched coupling.

10. The work machine of claim 9, wherein the autoswitched coupling is a free-wheel.

11. The work machine of claim 9, wherein the externally-switched coupling is a multiple-disc coupling.

12. The work machine of claim 8, wherein the at least one torque transmitter is provided in addition to the fluid coupling.

13. The work machine of claim 8, wherein the at least one torque transmitter is arranged between the motor and the fluid coupling.

14. The work machine of claim 8, wherein the at least one torque transmitter is arranged between the fluid coupling and the work machine.

15. The work machine of claim 8, constructed in the form of a vertical mill.

16. The work machine of claim 8, further comprising at least one further said drive arrangement.

17. A method for operating a drive arrangement for a work machine, comprising: temporarily interrupting a torque transmission between a motor and a fluid coupling of the drive arrangement, or temporarily interrupting a torque transmission between the fluid coupling and the work machine, wherein the torque transmission is interrupted between the fluid coupling and the work machine by separating the motor from the work machine, and further comprising: powering up the motor to a predetermined speed; re-establishing the torque transmission between the fluid coupling and the work machine; driving the work machine by using a torque transmission from the motor via a transmission apparatus to the work machine; and driving the fluid coupling by the motor without load to cool the fluid coupling, during or after powering up the motor.

18. The method of claim 17, wherein the torque transmission is interrupted between the motor and the fluid coupling by separating the motor from the fluid coupling and the work machine, and further comprising: powering up the motor to a predetermined speed; re-establishing the torque transmission between the motor and the fluid coupling, when the motor runs at the predetermined speed; and driving the work machine by using a torque transmission from the motor via a transmission apparatus to the work machine.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

(2) FIG. 1 is a sectional view of a drive arrangement for driving a vertical mill, in which a torque transmitter is arranged between the fluid coupling and the vertical mill;

(3) FIG. 2 is a sectional view of a drive arrangement for driving a vertical mill, in which a torque transmitter is arranged between the motor and the fluid coupling;

(4) FIG. 3 is a sectional view of a drive arrangement for driving a vertical mill, in which a first torque transmitter is arranged between the motor and the fluid coupling and a second torque transmitter is arranged between the fluid coupling and the vertical mill;

(5) FIG. 4 is a top view onto a vertical mill having four drive arrangements; and

(6) FIG. 5 is a graphical illustration of cooling curves of a stationary and a rotating fluid coupling, showing the temperature as a function of the time.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments may be illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

(8) Turning now to the drawing, and in particular to FIG. 1, there is shown a sectional view of a drive arrangement for driving a vertical mill, generally designated by reference numeral 2. The drive arrangement includes a torque transmitter 12 and a fluid coupling 8, with the torque transmitter 12 being arranged between the fluid coupling 8 and the vertical mill 2.

(9) The vertical mill 2 operates as a work machine and has a grinding table 20 which is rotatable about a vertical rotation axis A. A grinding track is embodied on the top side of the grinding table 20, upon which one or a number of grinding rollers 21 roll. The grinding table 20 is arranged in a torsion-resistant manner on a vertical upper end of a drive shaft 22 mounted in an axial bearing 23 and extending along the rotation axis A. A horizontally arranged gear rim 24 is arranged in a torsion-resistant manner on the shaft 22 below the grinding table 20. A drive arrangement, comprising a motor 4, a gearing 6 and a shaft 41 connecting the motor 4 and the gearing 6 serves to drive the drive shaft 22. The shaft 41 comprises a first part, namely a drive shaft of the motor 4, and a second part, a drive shaft of the gearing 6. Both parts are coupled by means of a fluid coupling 8. The motor 4 drives an output-side pinion 61 of the gearing 6 by way of the fluid coupling 8, said pinion 61 cogging with the gear rim 24.

(10) A torque transmitter 12 is arranged between the fluid coupling 8 and the gearing 6. This can be an automatically switching coupling, e.g. a free-wheel, if necessary with hydraulic support, or an externally-switched coupling, e.g. an electromagnetically or hydraulically switched multiple-disc coupling.

(11) During the milling operation, the torque of the motor 4 is transmitted via the shaft 41, the fluid coupling 8, the free-wheel 10 and the gearing 6 to the pinion 61 and the gear rim 24. A rotation of the motor 4 therefore results in a rotation of the grinding table 20 in the work direction of the mill 2. Since the fluid coupling 8 in this case transmits the motor power to the gearing 6, heat is generated in the fluid coupling 8 on account of the slip of the fluid coupling 8.

(12) When operation of the mill 2 is now temporarily stopped, the fluid coupling 8 can be cooled down in this break of the drive by the torque transmission between the fluid coupling 8 and the mill 2 being temporarily interrupted and the fluid coupling 8 being rotated idling by the motor.

(13) Since on account of the free-wheel 10 in this case the fluid coupling 8 transmits no power to the gearing 6, the slip of the fluid coupling 8 is almost zero and there is no significant heat generation in the fluid coupling 8. However, the rotation causes the fluid coupling 8 to ventilate and a large heat discharge from the fluid coupling 8 takes place so that the fluid coupling 8 essentially cools down more quickly than when stationary; as a result the drive is ready to start again relatively quickly.

(14) In the case of the free-wheel, the motor 4 can be operated counter to the work direction of rotation, i.e. backwards. In the case of the detached multiple-disc coupling, the motor 4 can be operated in any direction, forwards or backwards.

(15) In the event that the mill has to be started up from stationary, the switchable torque transmitter 12 is also advantageous. By the torque transmission between the fluid coupling 8 and the mill 2 being temporarily interrupted, the motor can be brought to a predetermined speed without load. Only after a defined speed of the motor has been achieved will the torque transmission between the fluid coupling and the work machine be re-established, i.e. the motor is coupled to the work machine again.

(16) This is particularly important when the mill has a number of drives, as shown in the exemplary embodiment shown in FIG. 4. The top view onto the vertical mill shows four drive arrangements arranged evenly around the mill axis A at the positions 0, 90, 180, and 270 degrees, each comprising an electric motor 4, a shaft 41, a fluid coupling 8, a switchable torque transmitter 12 and a gearing 6 with an output-side pinion 61. The output pinions 61 of the drive arrangements all cog with a shared gear rim 24, which is connected to a milling table 20 in a torsion-resistant manner.

(17) In this case the motors 4 can generally not be accelerated at the same time, because this would result in the electricity-supply system becoming overloaded. Therefore, all motors 4 of the multiple point machine can be brought successively to idle speed, without the energy network being loaded with excessive current intensities. When all the motors 4 of the multiple point machine are up to speed, the clutch couplings 12 can be coupled simultaneously or according to a predetermined switching strategy. Therefore all drive trains in an optimal case simultaneously generate the drive torque, wherein the drive torque is not restricted in terms of level and its temporal availability is at a maximum.

(18) FIG. 2 shows a section of a drive arrangement for driving a vertical mill, in which a torque transmitter 11 is arranged between the motor 4 and the fluid coupling 8. Besides the difference that the torque transmitter 11 is arranged between the motor 4 and the fluid coupling 8 in the exemplary embodiment in FIG. 2, and not between the fluid coupling and the vertical mill in the exemplary embodiment in FIG. 1, the exemplary embodiment in FIG. 2 corresponds to that in FIG. 1.

(19) When a temporary interruption in the torque transmission between the motor 4 and the fluid coupling 8 is effected by means of the switchable torque transmitter 11, the motor 4 can be started up without the load of the work machine 2. Only after a defined speed of the motor 4 has been achieved will the torque transmission between the motor 4 and the fluid coupling 8 be re-established, i.e. the motor 4 is coupled to the work machine 2 again.

(20) This is particularly important when the mill has a number of drives, which cannot be started up simultaneously, because this would result in the electricity-supply system becoming overloaded. Therefore, all motors of the multiple point machine can be successively brought to idle speed, without the energy network being loaded with excessive current intensities. When all motors of the multiple point machine are up to speed, the clutch couplings can be engaged simultaneously or according to a predetermined switching strategy. Therefore in an optimal case all the drive trains generate the drive torque simultaneously, wherein the drive torque is not restricted in terms of degree and its temporal availability is at a maximum.

(21) FIG. 3 shows a section of a drive arrangement for driving a vertical mill, in which a first torque transmitter 11 is arranged between the motor 4 and the fluid coupling 8 and a second torque transmitter 11 is arranged between the fluid coupling 8 and the vertical mill 2. In this way the operator of the vertical mill 2 has complete freedom in terms of the manner in which he would like to perform the torque transmission, in order to achieve the afore-described advantageous technical effects.

(22) FIG. 5 shows a time-temperature diagram with cooling curves of a stationary fluid coupling and a rotating fluid coupling, which clarifies the temporal advantage which can be achieved by the invention. The time t is plotted in the unit hours h and minutes min from 0 to 5 hours to the right on the horizontal axis. The temperature is plotted in the unit degrees Celsius from 0 to 180 C. to the top on the vertical axis. The starting point of both curves is a fluid coupling heated to 160 C.

(23) The dashed curve is the cooling curve of the stationary fluid coupling. The stationary fluid coupling cools down relatively slowly and even after five hours of cooling time has still not reached the ambient temperature Tu of 50 C.

(24) The solid curve is the cooling curve of the rotating fluid coupling. The fluid coupling can be operated by the motor without load due to a temporary interruption in the torque transmission between the fluid coupling and the work machine, i.e. can be rotated. This results in a cooling ventilation of the fluid coupling. The load-free rotating fluid coupling cools down considerably faster than the stationary fluid coupling and has reached the ambient temperature Tu of 50 C. after approx. 50 minutes of cooling time.

(25) While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.