Technical Field of the Invention

The invention relates to a method and apparatus for reducing deformation and vibration of shafts.

State-of-the-art

The existing shafts deform under the action of an external force load and transfer the force load to the connected other devices. The force load is given either by the force acting on the driven part or by the gyroscopic effects acting on the shaft during its rotation. Deformation is reduced either by increasing the shaft diameter or by bearings with greater stiffness. Bearings with greater stiffness do not solve the reduction of the shaft deformation under force load at the overhanging end of the shaft and increasing the shaft diameter increases the weight or design dimensions.

It is an object of the present invention to provide a method and apparatus for reducing shaft deformation under force loading so as not to increase the weight and structural dimensions of the shaft.

Subject Matter of the Invention

The essence of the method of reducing shaft deformation under force load is that the working shaft is connected to at least one auxiliary shaft, at least one inner bearing or gear or drive is inserted between the working shaft and the auxiliary shaft, between the auxiliary shaft bearing and the frame or working shaft the operating elements of at least one actuator or drive are inserted, which are connected to the position or motion sensors of the working shaft or the auxiliary shaft and a force or torque acting against the force load is derived by the actuator or the drive on the basis of the signals from the position or motion sensors. To generate signals to the actuator or drive, the working shaft position relative to the frame is measured by the working shaft position sensor and the auxiliary shaft position relative to the frame is measured by the auxiliary shaft position sensor, or the working shaft position relative to the frame is measured by the working shaft position sensor or the auxiliary shaft position relative to the frame is measured by the auxiliary shaft position sensor and the relative position of the working shaft and the auxiliary shaft is measured by the sensor of the relative position of the working shaft and the auxiliary shaft, or the value of the movement of the working shaft is measured by the sensor of the movement of the working shaft and the mutual position of the working shaft and the auxiliary shaft is measured by the sensor of the mutual position of the working shaft and the auxiliary shaft, or the value of the movement of the auxiliary shaft is measured by the sensor of the movement of the auxiliary shaft and the mutual position of the working shaft and the auxiliary shaft is measured by the sensor of the mutual position of the working shaft and the auxiliary shaft, or the value of the working shaft movement is determined by the working shaft movement sensor and the value of the auxiliary shaft movement is determined by the auxiliary shaft movement sensor.

The essence of the device for reducing shaft deformation under force load consists in that it consists of a working shaft which is connected to the at least one auxiliary shaft by at least one inner bearing or gear or drive, whereas between the auxiliary shaft bearing and the frame or working shaft, the operating elements of at least one actuator or drive are being arranged and connected to the movement or position sensors of the working shaft or the auxiliary shaft. The actuator is arranged on the frame or between the auxiliary shaft bearing and the frame or the working shaft. The drive is arranged between the frame and the auxiliary shaft or between the auxiliary and working shaft. The working shaft is eventually forcibly connected to several auxiliary shafts.

The axis of the auxiliary shaft is coaxial or parallel or intersecting or skew to the axis of the working shaft. The auxiliary shaft and the working shaft are optionally provided with mating gear wheels. The auxiliary shaft is possibly counter-rotating to the working shaft.

Overview of Figures in Drawings

The attached figures schematically show an apparatus for reducing the deformation of a shaft under a force load, where

Fig. 1 shows the existing basic shaft support

Figures 2 to 15 show an alternative shaft support according to the invention, Fig. 16 shows an example of the application of the invention

Examples of Embodiments of the Invention

Fig. 1 shows a standard rotating working shaft 1 mounted in outer bearings 4 on a frame 5. This and other figures show situations in sectional view. This and other figures do not include the drive of the working shaft 1, which can be driven by an electric motor from the frame 5 or driven by flowing and/or expanding fluid in internal combustion engines, turbines, compressors, etc. On the right the working shaft 1 has overhanging end outside the support of bearings on which the external force load 12 acts from the driven equipment, for example from forces acting on the propeller, the fan, unbalances, uneven running, etc. Due to the force load 12, it occurs the bending deformation of the working shaft 1 and/or the increased load of the outer bearings 4 and/or (whirling) vibration of the working shaft 1 and equipment powered by it. Increasing the diameter of the working shaft 1 or increasing the stiffness of the outer bearings 4 does not solve the problem. In addition, the deformation of the working shaft 1 causes an increase in imbalances, thus adding/ increasing the force load 12. The needed solution would be to place under the force load 12 the support of other outer bearings 4 connected to the frame 5. However, this is not possible because the frame 5 and the working shaft

1 have nothing to lean on.

Fig. 2 shows a solution which reduces the deformation of the working shaft 1. from Fig. 1 and replaces the bearing support from the inaccessible frame 5. The working shaft 1 is formed as a hollow shaft. Inside the working shaft 1 there is placed a parallel, in this case coaxially immovable auxiliary shaft 2 connected to the frame 5. The working shaft 1 is mounted on external bearings 4 on the frame 5. In the area of external force load 12 the working shaft 1. is mounted on another (additional, auxiliery) inner bearing 10 which is connected to the auxiliary shaft

2 by an actuator 3 provided with controls acting on both the working shaft 1 and the auxiliary shaft 2. The actuator 3 removes or reduces the bending deformation of the working shaft 1 according to the deformation measurement, otherwise the inner bearing 10 would suffice located in the area of action of the external force load 12. The use of the actuator 3 is primarily necessary due to the flexibility of the auxiliary shaft 2, the deformation of which must be measured and compensated by the actuator 3. However, the actuator 3 is also used to improve the dynamic response of the working shaft 1 to a variable force load 12, e.g. damping the oscillation of the working shaft 1. The inner bearing 10 connected to the actuator 3 can advantageously be replaced by a magnetic bearing which contains control of forces acting from the bearing on the shaft.

Bearings can be rolling, sliding, hydraulic (hydrostatic, hydrodynamic), pneumatic (aerostatic, aerodynamic), magnetic.

The position of the working shaft 1 is measured by the position sensor 6 of the working shaft 1 and the position of the auxiliary shaft 2 is measured by the position sensor 7 of the auxiliary shaft 2 relative to the frame 5. These sensors 6 and 7 serve to control the actuator 3 arranged between the auxiliary shaft 2 and the auxiliary inner bearing 10.

The actuator 3 acts on the working shaft 1 against the action of the external force load 12 and thus reduces/compensates for the deformation of the working shaft 1 caused by the external force load 12, and measured by the position sensor 6 of the working shaft 1.

The actuator 3 leans on the auxiliary shaft 2, which eventually deforms, which deformation can be compensated by the action of the actuator 3 on the working shaft 1 on the basis of information from the position sensor 7 of the auxiliary shaft 2.

However, the deformation and damping of the vibration of the working shaft 1 is improved only by the use of internal bearings 10 located in the area of external force load 12. Bringing the auxiliary shaft 2 into the area of external force load 12 substantially replaces the needed support of the working shaft 1 with the frame 5, which, however, is inaccessible in this area of action of the external force load 12. However, the actuator 3 connected to the inner bearing 10 makes it possible to increase the dynamic rigidity of the inner bearing 10.

The actuators 3 can be controlled drives, but also passive dampers or dampers connected to springs. Drives can be electric, hydraulic, pneumatic, electromagnetic, magnetic, piezoelectric and others.

Fig. 3 shows a variant of the solution of Fig. 2. Here the working shaft 1 is mounted on the outer bearing 4 on the frame 5 and on the inner bearings 10 on the auxiliary shaft 2. Here the inner bearing 10 connected to the auxiliary shaft 2 by the actuator 3 is used next to the place of application of the external force load 12 and in a place which is outside the action of the external force load 12.

In this way the different modal shapes of the vibration of the working shaft 1 can be influenced. Further it is shown that the measurement of the position of the auxiliary shaft 2 relative to the frame 5 by the position sensor 7 can be replaced at the bearing on the left by a relative position sensor 8 of the working shaft 1 and the auxiliary shaft 2. A combination of position sensor 6 and relative position sensor 8 is used to measure the individual positions of the working shaft hand the auxiliary shaft 2, similarly to the measurement in Fig. 2. Similarly shaft 1 and auxiliary shaft 2, similarly to the measurement in Fig. 2, a combination of position sensor 6 and relative position sensor 8 is used. Similarly, instead of the position sensors 6 and 7, the combination of the position sensor 7 of the auxiliary shaft 2 relative to the frame 5 and the relative position sensor 8 of the working shaft 1 and the auxiliary shaft 2 is used for the bearing on the right.

Fig. 4 shows an alternative to the solution of Fig. 2. In contrast to Fig. 2, the outer bearings 4 are replaced by inner bearings 10 on the auxiliary shaft 2 to mount the working shaft 1. Furthermore, the actuator 3 acting on the inner bearing 10 is solved by an actuator 3_located on the frame 5 outside the shafts 1, 2. The actuator 3 here acts on the inner bearing 10 by means of control elements, in this case rods 14 and rotary joints 15,. Thus, the required space for the actuator 3 acting on the inner bearing 10 can be reduced. The actuator 3 is controlled in this bearing by the relative position sensor 8 of the working shaft 1 and the auxiliary shaft 2 and further by the movement sensor 9z of the auxiliary shaft 2 formed for example by an accelerometer, which replace the position sensor 6 of the working shaft 1 and the position sensor 7 of the auxiliary shaft 2. The implementation of the sensors 92 and 8 is easier, but the deformation of the auxiliary shaft 2 cannot be fully captured. However, it is possible to dampen the vibrations of the shafts.

Fig. 5 shows an alternative to the solution of Figs. 2-4. Here the working shaft 1 is with the original cross section. On the contrary, the stationary auxiliary shaft 2 is hollow and the working shaft 1 is arranged coaxially therein. The working shaft 1 is mounted on inner bearings 10, on which the actuators 3 from the auxiliary shaft 2 act. The auxiliary shaft 2 is shorter, the working shaft 1 is overhanging with respect to the inner bearings 10 and the inner bearings 10 cannot act on the working shaft 1 in the area of external force load 12, but the actuators 3 nevertheless reduce the deformation of the working shaft 1 and/or reduce the increased load on the inner bearings 10 and/or reduce the vibration of the working shaft 1 and the device driven by it. A possible combination of sensors is also shown here. Position sensors 6 and 7 or relative position sensors 8 of the shafts and movement sensor 9i of the working shaft 1 formed, for example, by an accelerometer can be used. The implementation of movement sensors 9i and 8 is easier, but the deformation of the auxiliary shaft 2 cannot be fully captured. However, it is possible to dampen the oscillations of the shafts.

The fixed (immobile attached) hollow auxiliary shaft 2, inside which the working shaft 1 is located, has the advantages that, without increasing the moment of inertia and increasing the requirements on balancing of the working shaft 1, the equivalent of good balance, high rigidity and little or no deformation of the working shaft 1 can be achieved. The position sensors 6 and 7 of the shafts 1 and 2 can be laser beam sources and a CCD or PSD element. The relative position sensors 8 of the working and auxiliary shafts 1 and 2 can be capacitive, eddy currents, magnetic, laser interferometers. The movement sensors 9i of movement of working and auxiliary shafts 1 and 2 can be accelerometers.

Fig. 6 shows another alternative solution of Figs. 2-4. Here, the working shaft 1 with the original cross section is fixed and attached to the frame 5. A rotating part 16 is movably mounted on the working shaft 1, which is subjected to an external force load 12, which is transmitted to the working shaft 1 via the connection of the working shaft 1 and the rotating part 16. On the other hand, the stationary auxiliary shaft 2 is hollow and the working shaft 1 is arranged coaxially therein. The working shaft 1 is mounted on inner bearings 10 on which the actuators 3 from the auxiliary shaft 2 act. The auxiliary shaft 2 is shorter, the working shaft 1 is overhanging with respect to the inner bearings 10 and the inner bearings 10 cannot act on the working shaft 1 in the area of connection with the rotating part 16 and thus in the area of external force load 12, but the actuators 3 nevertheless reduce the deformation of the working shaft 1 and/or reduce the increased load on the inner bearings 10 and/or reduce the vibration of the working shaft 1 and the rotating part 16.

Fig. 7 shows a solution by means by means of an auxiliary shaft 2 which is not coaxial but parallel to the working shaft 1. The auxiliary shaft 2 acts on the working shaft 1 through co-engaging gears 13. The actuator 3 acts on the outer bearing 4 on the auxiliary shaft 2, and thus acts on the auxiliary shaft 2, which acts on the working shaft 1 via the gears 13 and reduces its deformation and/or dampens its vibrations. The external force load 12 acts outside the outer bearings 4 between the gear support 13 and the outer bearings 4. The shafts 1 and 2 can be intersecting or skew with a suitable choice of the gear teeth of gears 13.

Fig. 8 shows an alternative solution of Fig. 7. A gear wheel 13 on the stationary auxiliary shaft 2 is mounted on an inner bearing 10 with an actuator 3. The actuator 3 acts on the working shaft 1 via an inner bearing 10 and gears 13. External force load 12 acts outside the outer bearings 4 and outside the support by the gears 13, but the support by the gears 13 is closer to the external force load 12, which can be thus compensated. The shafts 1 and 2 can be intersecting or skew with a suitable choice of the gear teeth of gears 13.

Fig. 9 shows a solution for the case where the working shaft 1 is subjected to a gyroscopic moment due to the rotation of the working shaft 1 about another axis 20 of rotation besides the axis 11 of rotation. The working shaft 1 is located coaxially in a hollow auxiliary shaft 2 which rotates counter-rotating to the working shaft 1. Then the gyroscopic moment acting on the auxiliary shaft 2 has the opposite sign than the gyroscopic moment acting on the working shaft 1. The opposite action of the gyroscopic moments on shafts is compensated by actuators 3. It is also shown here that the movement sensors 9 can be used as a movement sensor 9g of the auxiliary shaft 2 or a movement sensor_9i of the working shaft 1. The data from movement sensors 9i and 92 can be used primarily for damping of shaft vibration.

Fig. 10 shows an alternative to the solution of Fig. 8. The axis 11 of the auxiliary shaft 2 is intersecting and/or skew to the axis 11 of the working shaft L

Fig. 11 shows a hollow auxiliary shaft 2 led out of the frame 5 into the area of action of an external force load 12, caused for example by an unbalanced rotor formed, maybe, by an aircraft propeller. From the hollow auxiliary shaft 2, the actuator 3 acts on the working shaft 1 by means of the inner bearing 10.

The traditional solution would be to increase the cross- section of the working shaft 1 to reduce its compliance and deformation, which would increase the moment of inertia of the rotating working shaft L Here the cross-section of the working shaft 1 and thus its moment of inertia is maintained and the required increase in stiffness is achieved by supporting the inner bearing 10 from the auxiliary shaft 2. In addition, an actuator 3 controlled by the data from the position sensors 6 and 7 of the shafts j. and 2 relative to the frame 5 is used here. This makes it possible to dynamically compensate for the deformation of the working shaft 1 and/or to dampen its vibrations.

Fig. 12 shows a solution which, in contrast to the previous cases, reduces the torsional deformation of the working shaft 1 of Fig. 1 and provides a compensating torsional moment from the inaccessible frame 5. In Fig. 12, the working shaft 1 is loaded by an external force load 12 consisting of a torsional moment. The auxiliary shaft 2 is movable, is hollow and the working shaft 1 is located coaxially therein. The working shaft 1 is mounted on inner bearings 10 relative to the auxiliary shaft 2 and the auxiliary shaft 2 is mounted in outer bearings 4 on the frame 5. The auxiliary shaft 2 is driven by a drive 17 from the frame 5. The drive 17 here consists of an electric motor whose rotor is a control element for deriving the compensating torsional torque. The auxiliary shaft 2 acts on the working shaft 1 through the gears 13 with a torsional torque from the drive 17, thus reducing the torsional deformation and/or vibration of the working shaft 1. A position sensor 7 of the auxiliary shaft 2 relative to the frame 5 and a relative position sensor 8 of the working shaft 1 and the auxiliary shaft 2 are used. Here, the position sensors 7 and 8 measure the angular positions of the shafts about the axis 11 of rotation. According to the deviation of the angular position, the drive 17 is controlled, which acts on the working shaft 1 via the auxiliary shaft 2 and the gears 13 and compensates by the torsional moment the torsional deformation of the working shaft 1 caused by the external torsion moment 12. This solution can also be implemented in a manner similar to Fig. 2 with a hollow working shaft 1.

Fig. 13 shows another solution of the case of Fig. 12. Here, the auxiliary shaft 2 is fixed to the frame 5. The drive 17 is realized here by an electric motor between the auxiliary shaft 2 and the working shaft 1. Two drives 17 are used, which act on the working shaft 1 in several places and reduce torsional deformations and/or vibrations of the working shaft 1 in sections and thus more evenly and better.

Furthermore, an inner bearing 10 with an actuator 3 is used here to reduce the bending deformation and/or vibration of the working shaft 1. The working shaft 1 is subjected to an external force load 12 consisting of both a torsional moment and a bending force. This solution can also be implemented in a manner similar to Fig. 2 with a hollow working shaft 1.

Fig. 14 shows an alternative to the solution of Fig. 11 in that the auxiliary shaft 2 is not coaxial but parallel to the working shaft 1. The auxiliary shaft 2 can also be skew or intersecting to the working shaft 1. A position sensor 6 of the working shaft 1 and a position sensor 7 of the auxiliary shaft 2 relative to the frame 5 are used. The sensors measure the angular positions of the shafts about the axis 11 of rotation. It is further shown, similarly to Fig. 13, that the auxiliary shaft 2 is also used to compensate for bending deformations and/or vibrations of the working shaft 1 by an outer bearing 4 with an actuator 3. For them, the position sensors 6 and 7 also measure the bending deformation of the shafts.

Fig. 15 shows a solution in which more of the auxiliary shafts 2 is used. The working shaft 1 is inside three mutually inserted auxiliary shafts 2, of which the inner and outer ones are movable and the middle one is stationary (immovable). The movable and stationary auxiliary shafts 2 can be inserted between them in a different order of movability. The auxiliary shafts 2 act on the working shaft 1 in different places, thus improving the uniformity of the compensation of its bending and torsional deformations. However, the auxiliary shafts 2 can be different, not only coaxial. It is possible to combine auxiliary shafts 2 coaxial, parallel, intersecting, skew, which simultaneously act on one working shaft 1.

The drives 17 can be electric, hydraulic, pneumatic, electromagnetic, magnetic, piezoelectric and others.

Fig. 16 shows an aircraft 18 moving in a turn 19 about another axis of rotation 20 and the working shaft 1 of its propeller motors is equipped with the solution according to Fig. 9, which compensates for the gyroscopic effects acting on the working shaft L

Figures 7 to 10 do not show all the necessary sensors 6 to 9 for controlling the actuators 3.

The working shafts 1 and the auxiliary shafts 2 can be with full cross-section or hollow, movable or stationary (immovable), coaxial, parallel, intersecting, skew and there may be more auxiliary shafts.

If the shaft is movable and rotates, this is indicated by arrows in the figures.

All the variants described can be combined in various ways. Actuators 3 are computer controlled.