Coupling arrangement

The present invention relates to a coupling arrangement in accordance with the preamble of claim 1.

When operating printing machines, it is advantageous, for example, to drive certain rolls, e.g. the rolls of a dampening unit of a printing machine, at different peripheral speeds in various operating and setup phases. A known way of achieving this from the practical experience of the applicant is to use printing machines, the dampening unit rolls of which are driven selectively at one of two predetermined transmission ratios by way of a drive train.

A drive train of this kind typically comprises at least one spur gear stage. In this case, the desired transmission ratio is selected by means of a coupling arrangement, for example, by connecting in each case one of two loose wheels rotating about a drive output shaft to the drive output shaft for conjoint rotation. On the drive input side, both loose wheels are continuously operatively connected to a drive motor by the drive train. The known coupling arrangement is pneumatically actuated and is designed in such a way that, in the unpressurized state of the coupling arrangement, the roll is driven at a first transmission ratio by means of a first coupling and by means of the first loose wheel, and that, when pressure is applied to the coupling arrangement, the roll is driven at a secondtransmission ratio by means of a second coupling and by means of the second loose wheel. To achieve different transmission ratios, the two loose wheels have different diameters. Each loose wheel is connected to the outer plates of the associated coupling for conjoint rotation, while the inner plates of each coupling are connected to the drive output shaft for conjoint rotation. In this coupling arrangement, therefore, just two operating positions are possible, in each of which there is a torque-transmitting connection between the drive motor and the roll.

It is the object of the present invention to develop a coupling arrangement described at the outset in such a way that another operating position can be selected in addition to the existing operating positions. At the same time, the outlay on construction and the required installation space should be kept as small as possible. It is likewise the intention to provide a printing machine having a coupling arrangement of this kind.

This object is achieved by means of a coupling arrangement in accordance with patent claim 1 and by means of a printing machine in accordance with patent claim 10. The dependent claims contain preferred developments of the invention.

The coupling arrangement according to the invention accordingly has a first and a second loose wheel, both of which are arranged in such a way as to be rotatable about a drive output shaft, wherein in each case one of the two loose wheels can be selectively connected to a drive output shaft for conjoint rotation by means of a first and a second coupling respectively. The two couplings can be actuated by means of a piston-cylinder unit to which a pressure medium can be applied. According to the invention, the piston of the piston-cylinder unit is designed as a stepped piston. A "stepped piston" is taken to refer to a piston which is of multi-part construction and, as a result, can trigger a plurality of predeterminable actuating strokes in succession, depending on the pressure applied.

The individual actuating strokes can differ in direction and magnitude.

It is possible, for example, for the drive output shaft to be arranged directly and rigidly on a roll, e.g. on a dampening roll of a printing machine, or the roll is driven by means of further transmission stages.

With a coupling arrangement of this kind, it is possible to achieve two different transmission ratios and hence two different peripheral speeds of the driven roll by means of the two loose wheels, which are operatively connected to a drive motor by way of the drive train, when the piston-cylinder unit is in its two end positions. In addition, the stepped piston makes it possible to select a central operating position, in which both couplings are open and there is no torque-transmitting connection between the drive and the drive output shaft, i.e. the roll. Three operating positions are thus possible, even with a piston to which a pressure medium can be applied on only one side, if the piston is preloaded in the opposite direction by a spring. As compared with a double-acting piston-cylinder unit, the outlay on construction and the outlay on control are small. Thus, the piston-cylinder unit to which a pressure medium can be applied on one side needs only one pressure space, for example, requiring appropriate sealing. Moreover, only one compressed air connection has to be fitted to the rotating shaft.

The stepped piston preferably has a fixed piston, which is connected in an axially fixed manner to the drive output shaft, and a drag piston, which can be moved axially, while the cylinder of the piston-cylinder unit is preferably arranged in such a way relative to the drive output shaft that it can be moved axially. The two couplings are each operatively connected to the cylinder in such a way that the axially movable cylinder closes one of the two couplings in each of the two end positions, thus transmitting the drive torque to the drive output shaft and onward to the roll via the respectively closed coupling and the loose wheel associated therewith.

The cylinder assumes a first end position when no pressure is being applied to the piston-cylinder unit and the cylinder is pushed into the first end position by a spring, e.g. one or more helical compression springs. The spring can preferably be supported against the axially immobile fixed piston. In the first end position of the cylinder, the first coupling is closed and thus transmits a first torque supplied on the drive input side from the first loose wheel to the drive output shaft. In the first end position, the second coupling is open and cannot transmit any torque.

The cylinder assumes a second, opposite, end position when a high pressure is applied to the piston-cylinder unit. In the second end position of the cylinder, the second coupling is closed and transmits to the drive output shaft a second torque supplied on the drive input side. In the second end position, the first coupling is open and does not transmit any torque.

The cylinder assumes the central operating position, in which the coupling arrangement does not transmit any torque, when a low pressure is applied to the piston-cylinder unit.

The low pressure must be at least sufficient to ensure that the resulting pressure force exceeds the spring force of the spring described above, thus moving the cylinder out of the first end position, against the spring force, until it rests against the drag piston. In this state, the pressure can be increased by a certain additional amount without the cylinder moving further. However, the low pressure must not be so large that the cylinder is pushed into the second end position, taking the drag piston along with it.

The piston-cylinder unit is preferably of annular design and arranged coaxially with the drive output shaft. This advantageously enables the piston-cylinder unit to be arranged between the two loose wheels on the drive output shaft, thereby making optimum use of the installation space required.

The fixed piston and the drag piston are each preferably designed as annular pistons, with the fixed piston being arranged within the annular piston and the drag piston being arranged on the outside. In this case, the drag piston is arranged in such a way that it can be moved axially both relative to the fixed piston and relative to the cylinder.

According to another preferred embodiment of the coupling arrangement, the fixed piston is designed as an annular piston, and the drag piston consists of a plurality of individual pistons which are arranged in a manner distributed over the circumference of the fixed piston and in such a way that they can be moved axially relative to the fixed piston.

Another preferred embodiment of the invention provides for the pressure medium of the piston-cylinder unit to be supplied by means of at least one bore in the drive output shaft.

This saves additional installation space and makes it possible to dispense with further separate lines and connection elements for supplying the pressure medium.

Said couplings are preferably designed in such a way that each coupling has at least one outer plate, which is connected to the respectively associated loose wheel for conjoint rotation, and at least one inner plate, which is connected to the drive output shaft for conjoint rotation, on a plate ring. In the two end positions of the cylinder, one coupling in each case is acted upon by the cylinder in such a way that the corresponding outer plate is connected in a torque-transmitting manner to the associated inner plate. Each coupling is preferably designed as a multi-disk friction clutch having a plurality of outer and inner plates which are pressed against one another by the cylinder in the corresponding end position.

Finally, the present invention relates to a printing machine having a dampening unit transmission, which has a coupling arrangement described above.

The invention is explained in greater detail with reference to a preferred embodiment, which is illustrated in the following figures.

Of the figures,

Fig. 1 shows a prior-art coupling arrangement having two operating positions, Fig. 2 shows a first embodiment of the coupling arrangement according to the invention,
having an annular piston as a drag piston, and Fig. 3 shows a second embodiment of the coupling arrangement according to the invention, having a plurality of individual drag
pistons.

In the prior-art coupling arrangement 1 illustrated in figure 1, as in the coupling arrangement according to the invention, the essential components are arranged either in a fixed manner on the drive output shaft 2 or in such a way as to be rotatable about the center line 3 thereof.

The coupling arrangement 1 includes a first loose wheel 4 and a second loose wheel 5, to which a first coupling 6 and a second coupling 7 arranged adjacent thereto are respectively assigned. Both loose wheels 4 and 5 are rotatably supported on the drive output shaft 2 by means of rolling contact bearings 16 and 17, and both loose wheels are embodied as gearwheels in this embodiment. Arranged between the two couplings 6 and 7 in the axial direction is a piston-cylinder unit 20, wherein the piston 21 is arranged rigidly with respect to the drive output shaft 2, and the cylinder 22 is arranged in such a way that it can be moved axially relative to the drive output shaft.

Each coupling 6, 7 consists of outer plates 8, 9 and of the plate ring 10, 11 having inner plates arranged in a fixed manner. In this embodiment, each coupling 6, 7 is designed as a multi-disk friction clutch, and therefore the outer plates 8, 9 and the inner plates of the plate rings 10, 11 are arranged alternately in series, facing each other, in the axial direction. The outer plates 8, 9 of the first and the second coupling 6 and 7 are each connected to the respectively associated loose wheel 4 and 5 for conjoint rotation by a plate driver 12 and 13, respectively, and arranged in such a way that they can be moved in the axial direction.

The inner plates of the plate rings 10 and 11 are connected to the drive output shaft 2 for conjoint rotation and are likewise arranged in such a way that they can be moved in the axial direction. The plate rings 10 and 11 furthermore have a pressure plate 14 and 15, respectively, each of which is arranged on the opposite side of the plate packs from the piston-cylinder unit 20 and is connected securely to the drive output shaft 2. The axially movable outer and inner plates of the two couplings 6 and 7 are supported on the pressure plates 14 and 15, respectively, when the associated coupling 6, 7 is closed, and the plates are pushed against one another by the piston-cylinder unit 20 for this purpose.

The piston-cylinder unit 20 has an annular cylinder 22, which can be moved axially relative to the drive output shaft 2 and which consists of a cylinder casing 23 and two cylinder caps 24 and 25, which are connected rigidly to the cylinder casing 23. Arranged within the annular cylinder 22 is a piston in the form of an annular piston 21, which is connected rigidly to the drive output shaft 2 by way of a bush 18. The annular cylinder 22 is thus arranged in such a way that it can be moved axially relative to the annular piston 21 and to the drive output shaft 2. To secure the connection for conjoint rotation, the drive output shaft 2 has inserted into it a key 19, which engages in corresponding key slots in the bush 18 and in the plate rings 10 and 11.

The movable annular cylinder 22 is acted upon continuously by a compression spring 26, which is supported against the annular piston 21 and pushes the annular cylinder 22 in the direction of the first coupling 6. On the side of the annular piston 21 facing the second coupling 7 there is a pressure space 27, to which a pressure medium can be applied.

When a pressure medium is applied to this pressure space 27, the annular cylinder 22 is pushed in the direction of the second coupling 7. The pressure medium, which is provided by a pressure medium source that is not shown, is supplied to the pressure space 27 by means of a pressure medium channel 31 which leads through the drive output shaft 2 and the bush 18 to the pressure space 27. The supply of pressure medium is controlled by means of control valves (not shown), which are connected to an electronic control unit, for example, in a manner which allows signal transmission. The annular pressure space 27 is bounded at the inner circumference by the bush 18, on which the cylinder cap 25 is mounted in a manner which prevents the pressure medium from leaking and allows axial movement. At the outer circumference, the pressure space 27 is bounded by the cylinder casing 23 and, at the side, by the cylinder cap 25 and the piston 21.

The operation of the coupling arrangement is described below. Both loose wheels 4 and 5 are continuously operatively connected to a drive motor by means of a drive train (not shown) . As long as no compressed air is applied to the pressure space 27, the annular cylinder 22 is pushed in the direction of the first coupling 6 by the compression spring 2 6 until the first coupling 6 is closed. The annular cylinder 22 is thus in a first end position. In this case, the axially movable outer plates 8 are pressed against the inner plates of the plate ring 10, giving rise to frictional engagement between the plates and ensuring that the outer plates 8 and the plate ring 10 with the inner plates no longer turn relative to one another. A flow of power is thus established from the drive motor, via the first loose wheel 4, to the drive output shaft 2 and onward to the roll concerned.

As soon as compressed air is applied to the pressure space 27 via the pressure medium channel 31 and the pressure in the pressure space 27 is so great that the pressure force on the annular cylinder 22 is greater than the spring force due to the compression spring 26, the annular cylinder 22 moves out of the first end position thereof in the direction of the second end position, in which the annular cylinder 22 is pressed against the second coupling 7, with the result that the second coupling 7 is closed. In this case, the outer plates 9 are pressed against the inner plates of the plate ring 11, giving rise to frictional engagement and ensuring that the outer plates 9 can no longer turn relative to the plate ring 11. A flow of power is thus established from the drive motor, via the second loose wheel 5, to the drive output shaft 2 and onward to the roll concerned.

As explained at the beginning of this document, a coupling arrangement of this kind has just two operating positions, namely a first operating position, in which the annular cylinder is held in the first end position by the compression spring 26, and a second operating position, in which the annular cylinder 22 is held in the second end position by the application of pressure. In both operating positions, a flow of power is established from the drive train on the drive input side to the roll on the drive output side.

In contrast, the coupling arrangement 1 according to the invention, which is illustrated in figure 2, allows three operating positions, although the construction of the coupling arrangement 1 is the same in many parts to the construction of the coupling arrangement described above. There are therefore many identical parts, and no additional installation space is required for the coupling arrangement according to the invention.

Because of the similar construction, identical parts are provided with identical reference numerals in all the figures of this document, and only the components and functions which differ from the prior-art embodiment described above are described in greater detail below.

The coupling arrangement 1 according to the invention, which is illustrated in figure 2, differs essentially from the known arrangement in accordance with figure 1 in the construction of the piston. According to the invention, the piston is constructed as a stepped piston and, in addition to the fixed piston 28 connected securely to the drive output shaft 2, also comprises an axially movable drag piston 29. The drag piston 29 can be moved axially both relative to the fixed piston 28 and the drive output shaft 2 and relative to the annular cylinder 22. The axial travel of the drag piston 29 relative to the annular cylinder 22 is limited by the caps 24 and 25 of the latter, and its axial travel relative to the fixed piston 28 is limited by a mechanical stop 30 on the drag piston 29.

The stepped piston is thus of multi-part construction and triggers a plurality of actuating strokes predetermined by the geometry of the components, depending on the level of the actuating pressure, e.g. that of an actuating medium and of a spring. Each actuating stroke corresponds to a particular operating position of the coupling arrangement.

In the unpressurized state, the annular cylinder 22 is pushed into the first operating position in the direction of the first coupling 6 and held there by the spring 26, with the result that the first coupling 6 is closed and torque transmission takes place from the drive train on the drive input side, via the first loose wheel 4, to the drive output shaft 2. This first operating position is maintained for as long as the pressure in the pressure space 27 is below a lower threshold value.

A second operating position is present when the cylinder is in a second end position. This occurs when high pressure above an upper threshold value is applied to the coupling arrangement, with the result that the annular cylinder 22 is pushed completely in the direction of the second coupling 7 by the pressure built up in the pressure space 27. In this case, the drag piston 2 9 is moved in the axial direction relative to the fixed piston 28.

In this second operating position, the second coupling 7 is closed, and torque transmission takes place from the drive train on the drive input side, via the second loose wheel 4, to the drive output shaft 2. The second operating position is set and held when the pressure in the pressure space 27 is above an upper threshold value.

Finally, a third operating position is obtained when the pressure in the pressure space is between the lower and the upper threshold value. In this case, the pressure is so high that the spring force of the compression spring 26 is overcome and the annular cylinder 22 is moved from the first end position thereof in the direction of the second end position, against the spring force, until cylinder cap 24 rests against the drag piston 29 after a certain travel. In this central operating position, the pressure in the pressure space 27 is then only effective on the surface of the fixed piston 28 because the effect of the pressure on the surface of the drag piston 29 is canceled out by the abutting cylinder cap 24 on the opposite side from the pressure space. The annular cylinder 22 therefore initially remains stationary in the central position, the third operating position, at a pressure above the lower threshold value. In this third operating position, both couplings 6 and 7 are open, and no torque is transmitted from the drive train to the drive output shaft 2.

If the pressure in the pressure space 27 rises further, the annular cylinder 22 takes the drag piston 29 along in the direction of the second end position from an upper threshold value. As long as the pressure in the pressure space 27 is maintained above the upper threshold value, the coupling arrangement remains in the second operating position, which corresponds to the second end position of the annular cylinder 22.

The upper and the lower threshold value of the pressure for the central position are determined essentially by the spring stiffness and the geometry of the drag piston.

Figure 3 shows another embodiment of the invention. This differs from the embodiment illustrated in figure 2 only in the design of stepped cylinder. According to figure 3, the stepped piston can consist of the fixed piston 28 and of a plurality of individual drag pistons 29a, 29b arranged in a manner distributed over the circumference of the fixed piston. Instead of the individual compression spring 26 in figure 2, each individual drag piston 2 9a, 29b in this embodiment is also assigned an individual compression spring 26a, 26b, which together perform the same function as the individual compression spring 2 6 in the embodiment described above. In addition to the two individual drag pistons 29a and 29b visible in figure 3, it is also possible for further individual drag pistons to be
arranged on the fixed piston 28.

The operation of the embodiment shown in figure 3 is the same as that described above. Starting from the unpressurized state of the piston-cylinder unit 20 which can be actuated by means of a pressure medium and from the corresponding first operating position, the annular cylinder 22 moves against the spring force of all the individual compression springs 2 6a, 2 6b etc. when the pressure is increased beyond the lower threshold value, into the central, third operating position, in which both couplings 6 and 7 are open and no torque is transmitted. In the central operating position, cylinder cap 2 4 rests against one end of the individual drag pistons 29a, 29b etc.

If the pressure is increased beyond the upper threshold value, the annular cylinder 22, together with the individual drag pistons 2 9a, 2 9b, moves further in the direction of the second operating position, until the latter is reached, and remains there for as long as the pressure in the pressure chamber 27 remains above the upper threshold value. In the second operating position, the second coupling 7 is closed, and a torque is transmitted from the drive train, via the second loose wheel 5, to the drive output shaft 2.

Reference signs

1 coupling arrangement

2 drive output shaft

3 center line

4 first loose wheel

5 second loose wheel

6 first coupling

7 second coupling

8 outer plates

9 outer plates

10 plate ring with inner plates

11 plate ring with inner plates

12 plate driver

13 plate driver

14 pressure plate

15 pressure plate

16 rolling contact bearing

17 rolling contact bearing

18 bush

19 key

20 piston-cylinder unit

21 piston

22 annular cylinder

23 cylinder casing

24 cylinder cap

25 cylinder cap

26 compression spring

26a, 26b individual compression spring

27 pressure space

28 fixed piston

29 drag piston

29a, 29b individual drag piston

30 stop

31 pressure channel

Patent claims

1. A coupling arrangement (1) having a first and a second loose wheel (4, 5) , a first and a second coupling (6, 7), and a drive output shaft (2), wherein the first and the second loose wheel (4, 5) are arranged in such a way as to be rotatable about the drive output shaft (2), and wherein the couplings (6, 7) can be actuated in such a way, by a piston-cylinder unit (20) to which a pressure medium can be applied, that one of the two loose wheels (4, 5) can be selectively connected to the drive output shaft (2) for conjoint rotation, characterized in that the piston-cylinder unit (20) has a stepped piston.

2. The coupling arrangement as claimed in claim 1, characterized in that the stepped piston has a fixed piston (28), which is connected in an axially fixed manner to the drive output shaft (2), and a drag piston (29), which can be moved axially.

3. The coupling arrangement as claimed in claim 2, characterized in that the cylinder (22) of the piston-cylinder unit (20) is arranged in such a way that it can be moved axially relative to the drive output shaft (2) .

4. The coupling arrangement as claimed in one of claims 1 to 3, characterized in that the piston-cylinder unit (20) is of annular design and is arranged coaxially with the drive output shaft (2).

5. The coupling arrangement as claimed in claim 4, characterized in that the fixed piston (28) and the drag piston (29) are each designed as annular pistons.

6. The coupling arrangement as claimed in claim 4, characterized in that the fixed piston (28) is designed as an annular piston, and in that the drag piston (29) consists of a plurality of separate individual drag pistons (29a, 29b) which are arranged in a manner distributed over the circumference of the fixed piston.

7. The coupling arrangement as claimed in one of the preceding claims, characterized in that the pressure medium of the piston-cylinder unit (20) is supplied by means of at least one pressure medium channel (31) in the drive output shaft (2).

8. The coupling arrangement as claimed in one of the preceding claims, characterized in that each coupling (6, 7) has at least one outer plate (8, 9) , which is connected to the respectively associated loose wheel (4, 5) for conjoint rotation, and at least one plate ring (10, 11), which is connected to the drive output shaft (2) for conjoint rotation and has at least one inner plate secured thereon, wherein the outer plates (8, 9) can each be connected to the inner plates in a torque-transmitting manner.

9. The coupling arrangement as claimed in one of the preceding claims, characterized in that both couplings (6, 7) are designed as multi-disk friction clutches.

10. A printing machine having a dampening unit transmission, characterized by a coupling arrangement (1) as claimed in one of the preceding claims.