GEAR-SYSTEM ARRANGEMENT FOR DRIVING A VACUUM ROLL AND FOR SUPPORTING THE INTERNAL STRUCTURES OF A VACUUM ROLL

The present invention relates to a gear-system arrangement for driving a vacuum roll and for supporting the internal structures of a vacuum roll, which gear-system arrangement includes: a machine frame fitted to a supporting foundation, a carrier-bearing assembly attached inside the machine frame, for supporting the vacuum roll on the machine frame from outside the vacuum roll, a gearwheel attached to the vacuum roll, for driving the vacuum roll, a gear housing for transmitting torque, a drive-bearing assembly between the gearwheel and the gear housing, and a carrier ring for supporting the vacuum roll's internal structures from the machine frame.

A vacuum-roll gear-system arrangement, which is shown in Figure 1, is known from the prior art. The gear-system arrangement includes a machine frame, on which the vacuum roll is supported by a carrier-bearing assembly. The carrier-bearing assembly is generally attached to the inside of the machine frame, so that the vacuum roll is supported from its outer surface on the machine frame by the carrier-bearing assembly. The internal structures of the vacuum roll are supported by a carrier ring, which is attached to the machine frame. A gearwheel for driving the vacuum roll is attached to the vacuum roll. The gearwheel is supported by a drive-bearing assembly on a gear-system housing, from which the torque is transmitted through a torque support to the machine frame. The gearwheel is attached to a flange shaft that is a continuation of the shell of the roll. As the gearwheel and the gear-system housing are supported on each other, the gear-system housing is also supported on the flange shaft. The flange shaft, which is a continuation of the shell of the roll, is in turn supported with the aid of a

carrier-bearing assembly on the machine frame. The gear-system housing and the carrier ring are on the opposite side of the carrier-bearing assembly to the shell of the vacuum roll. A gear-system arrangement implemented using a construction of this kind is long, extending far out from the carrier-bearing assembly.

The drive gear system of a vacuum roll can also be set in bearings as disclosed in patent US 5 860 322. In the patent in question, a carrier-bearing assembly is used, by means of which the vacuum roll is supported from inside the vacuum roll. The gearwheel can then be attached to the outside of the vacuum roll, at the location of the carrier bearing, thus considerably shortening the length of the gear-system arrangement. In order for the carrier-bearing assembly inside the vacuum roll to be supported on the machine frame, the machine frame must be made more complex. In addition, as the vacuum roll is supported from the inside of the shaft of the vacuum roll on the machine frame inside the shaft, the vacuum connection is considerably reduced in size.

The invention is intended to create a gear-system arrangement, which is shorter than previously, for driving a vacuum roll and for supporting the internal structures of the vacuum roll. The characteristic features of the present invention are stated in the accompanying Claim 1. As the gear-system housing is on the opposite side of the carrier-bearing assembly to the carrier ring, the gear-system arrangement protrudes axially out from the centre point of the carrier-bearing assembly less than previously and thus less from the machine frame. This leaves more space on the drive side of the paper machine.

In the press in the press section of a paper machine, vacuum rolls are used to improve water removal from the press nips . Structures on the inside of the vacuum roll are used to guide the vacuum to the desired Darts of the surface of the vacuum

roll. A gear-system arrangement is used to drive the vacuum roll and to support the internal structures of the vacuum roll. The gear-system arrangement includes a machine frame supported on the foundation, in which machine frame the vacuum roll is in turn supported on a carrier-bearing assembly. In other words, the carrier-bearing assembly is on the inside of the machine frame, supporting the vacuum roll from outside indirectly on the machine frame. A gearwheel, through which the vacuum roll is driven, is attached to the vacuum roll. More specifically, the gearwheel attached to the vacuum roll is attached to the flange shaft of the vacuum roll. A gear housing, supporting the gearwheel, is attached to the machine frame. Between the gearwheel and the gear housing there is a drive-bearing assembly. In other words, the gearwheel and the drive-bearing assem- bly are supported on each other. In addition, a carrier ring, which is used to support the internal structures of the vacuum roll, is attached to the machine frame. Surprisingly, the gear housing is on the opposite side of the carrier-bearing assembly to the carrier ring. The solution according to the invention shortens considerably the length of the gear system and the flange shaft. The solution according to the invention is suitable for both slow and high-speed machines, so that there are extensive opportunities to apply it. In addition, the solution reduces costs, as the carrier ring is shortened and simplified. Further, the internal structures of the vacuum roll need not extend as far as previously, so that the dimension of the flange shaft can be shortened.

In one embodiment, the gearwheel has a single ring, thus mini- mizing the axial space requirement.

In a second embodiment, the gearwheel has helical gear toothing, which considerably reduces noise.

In a third embodiment, the helical gear toothing is at an angle of 1 - 10°, preferably 2 - 6°. As the anσle of the helical αear

toothing is small, it creates only a small axial force. Thus the load can be easily carried by groove ball bearings, which are preferably angular-contact bearings, and the total construction is economical.

In a fourth embodiment, the drive-bearing assembly is spring loaded. The spring loading acting on the bearings ensures that the bearings operate normally when using the gear-system arrangement even with a lighter loading, or even with a zero loading. In the construction according to the invention, a zero loading could cause considerable problems for the bearings . A zero loading can be avoided by using spring loading.

In a fifth embodiment, the gear-system arrangement includes a torque support to transmit the torque acting on the gear housing to the foundation. The gear housing is typically secured by the torque support to the machine frame, so that a slight degree of mutual play is allowed between the gear housing and the machine frame.

In a sixth embodiment, the axial protrusion of the carrier ring from the axial centre of the carrier-bearing assembly is less than 80 %, preferably less than 60 %, of the internal diameter of the carrier-bearing assembly. When the axial protrusion of the carrier ring is as small as this, the carrier ring can be manufactured with considerable economy.

In the following, the invention is described in detail with reference to the accompanying drawings showing some embodiments of the invention, in which

Figure 1 shows a gear-system arrangement according to the prior art, seen from the side of the vacuum roll, and

Figure 2 shows the gear system arrangement according to the invention, seen from the side of the vacuum roll, and

Figure 3 shows the gear-system arrangement according to the invention, seen from the end of the vacuum roll.

Figure 1 shows a gear-system arrangement 10 according to the 5 prior art on a foundation 18. The gear-system arrangement 10 includes a machine frame 16, to which the vacuum roll 12 is attached by means of a carrier-bearing assembly 20. The carrier-bearing assembly 20 is attached to the inside of the machine frame 16, so that the vacuum roll 12 is supported by

10 means of the carrier-bearing assembly 20 on the machine frame 16 from its flange shaft 32. The structures 14 inside the vacuum roll are supported by a carrier ring 28' which is attached to the machine frame 16. The carrier ring 28' can consist of several components, such as a carrier component 27' and

15 an extension component 29'. There is a breather hole 30 in the extension component 21' of the carrier ring 28'. The vacuum roll 12 includes a flange shaft 32 and a shell 34. A gearwheel 22, for driving the vacuum roll 12, is attached to the vacuum roll 12, more specifically to the flange shaft 32 of the vacuum

20 roll. The vacuum connection of the vacuum roll is connected to the carrier ring, or to the internal structures of the vacuum roll that are carried by it. The gear housing is secured to the carrier ring through a torque support. The gearwheel 22 is supported by a drive-bearing assembly 26 on the gear housing

25 24', which is secured to the machine frame 16. The gear housing 24' and the carrier ring 28' are on the opposite side of the carrier-bearing assembly 20 to the shell 34 of the vacuum roll 12. A gear-system arrangement implemented using a construction of this kind according to the prior art extends a long way from

30 the end of the machine frame and thus takes up a great deal of space.

Figure 2 shows the gear-system arrangement 10 according to the invention, which is used to drive the vacuum roll 12 through

35 the flange shaft 32 and support the internal structures 14 of the vacuum roll 12. The vacuum roll 12 includes a flange shaft

32, which is attached to the shell 34 of the vacuum roll 12. The gear-system arrangement 10 includes the machine frame 16, which is supported on a foundation 18. A carrier-bearing assembly 20, which usually consists of a single carrier bearing 21, is attached inside the machine frame 16. The carrier-bearing assembly 20 is used to support the vacuum roll 12 on the machine frame 16. More specifically, the carrier-bearing assembly 20 attached inside the machine frame 16 is used to support the vacuum roll 12 on the machine frame 16, from outside its flange shaft 32. A gearwheel 22 for driving the vacuum roll 12 is attached to the vacuum roll 12. The said gearwheel 22 is driven using a second smaller gearwheel, which is, in turn, driven by a motor. The gearwheel 22 is supported on a gear housing 24, which is secured to the machine frame 16. There is a drive- bearing assembly 26 between the gear housing 24 and the gearwheel 22. The gear-system arrangement 10 includes a carrier ring 28 for supporting the internal structures 14 of the vacuum roll 12 on the machine frame 16. In addition, the gear housing 24 is on the opposite side of the carrier-bearing assembly 20 to the carrier ring 28. Thus the carrier ring 28 is on the opposite side of the carrier-bearing assembly 20 to the shell 34 of the roll 12. The construction according to the invention permits the carrier ring to be made as a lighter structure. In addition, the carrier ring can be easily made as a single piece.

In the gear-system arrangement 10 shown in Figure 2, the carrier-bearing assembly 20 and the drive-bearing assembly 26 are in the same oil chamber 36. The construction becomes very compact, as the carrier and drive bearings can be lubricated using the same oil, i.e. the gear system and the carrier bearing are in the same oil chamber. In addition, only a single set of pipes are needed to transport the oil, which simplifies the totality of the construction. There is a breather hole 30 in the carrier ring 28.

In the gear-system arrangement shown in Figure 2, the internal diameter of the carrier-bearing assembly is 400 - 1200 mm, preferably 700 - 1000 mm and it is arranged to transmit a power of 100 - 1500 kW, preferably 600 - 1100 kW. The internal diame- ter of the carrier-bearing assembly 20 is two times the internal radius r.

In the gear-system arrangement shown in Figure 2, the axial protrusion 1 of the carrier ring 28 from the axial centre of the carrier-bearing assembly 20 is less than 80 %, preferably less than 60 %, of the internal diameter of the carrier-bearing assembly 20.

Figure 3 shows the gear-system arrangement 10 according to the invention, which includes a torque support 38 for transmitting the torque acting of the gear housing to the foundation 18. The transmission of the torque acting on the gear housing 24 to the foundation by using a torque support 38 permits the gear housing and the machine frame to be supported flexibly on each other. In turn, the flexible support between the gear housing and the machine frame permits the gearwheel to be attached rigidly to the vacuum roll.