Coupling device for connecting a damper unit to a shaft

Abstract

A coupling device (8) for coupling a damper unit (7) to a rotatable shaft (3) is able to be placed between the shaft (3) and the damper unit (7). The coupling device comprises a first yoke (9), fastenable to the shaft (3), and a second yoke (10) parallel to the first one and fastenable to the damper unit (7), and at least two mutually parallel bending springs (12) arranged between the first yoke (9) and second yoke (10). The free ends of the bending springs (12) are connected to the first yoke (9) and second yoke (10) respectively, such that the two yokes (9, 10) form a parallelogram together with the bending springs (12).

Description

[0001] COUPLING DEVICE FOR CONNECTING A DAMPER UNIT TO A SHAFT

[0002] The invention relates to a coupling device for coupling a damper unit to a rotatable shaft, so that forces and movements can be transmitted to the damper unit by means of the coupling device. Furthermore, the invention relates to a damper system with at least two damper units and two coupling devices. Furthermore, the invention relates to a spin test bench with a damper system.

[0003] To determine their fatigue strength, rotationally symmetrical components are typically subjected to a test procedure performed on a spin test rig, where the test specimens are spun to burst speed or another predefined speed. In addition, the rotor can be subjected to cyclic speed changes or temperature fluctuations, for example. Such a test rig is known from DE 1 125 206 A.

[0004] The rotor can be suspended from a thin, elastic shaft, for example, via its shaft journal, and accelerated. The rotor then rotates around its mass axis of inertia instead of its geometric axis, so that the rotor moves virtually free of imbalance forces. Since the shaft's elastic natural frequencies are usually passed through, and large deflections can occur, dampers are often used to limit the shaft deflection, thus limiting the amplitudes of the spin waves.

[0005] Common damping units are oil dampers. These consist of an oil-filled cylinder tube sealed at both ends by end pieces. A piston rod passes through one of the end pieces. This rod is connected inside the cylinder tube to a piston that slides sealed against the inner wall of the cylinder tube. A channel can run through the piston, acting as a throttle to slow the speed at which the piston is adjusted. Oil dampers are known, for example, from DE 37 26 031 C2.

[0006] DE 10 2011 087 909 B3 describes an arrangement for a component test bench, comprising a shaft for transmitting torque from a rotary drive to a component under test. The shaft is rotatably mounted in a bearing on both the component and drive sides. The component-side bearing is connected to a damping system in a hexapod arrangement, so that vibrations generated by imbalance are damped.

[0007] DE 10 2004 014 458 A1 discloses a damper for damping a front fork, e.g., of a motorcycle. The fork has an inner oil chamber with two inner oil chamber sections separated by a moving piston but fluidly connected by a line. The oil in the inner oil chamber sections can escape through a gap into an outer oil chamber, e.g., due to temperature changes.

[0008] EP 2 562 440 B1 discloses a damper system with a magnetic coupling. The magnetic coupling comprises two magnets to exert radial counterforces at radially opposite points around the rotor, so that no resultant force is exerted on the rotor when the rotor is centered in the damper system.

[0009] WO 2023 / 116979 A1 discloses an oil damper with an oil-filled inner oil chamber configured as a hollow chamber, which is connected via at least one passage to an outer oil chamber also containing oil. A piston rod extends through the passage and the inner oil chamber, which is movable in its longitudinal direction and connectable to an object to be damped. A piston attached to the piston rod divides the inner oil chamber into two inner oil chamber parts. The inner oil chamber parts are fluidly connected to one another via at least one oil passage means. A shaft guide element, which is not sealed with respect to the inner oil chamber, is arranged in the at least one passage, so that oil can flow from the inner oil chamber into the outer oil chamber.

[0010] US 2012 / 0 279 286 A1 deals with a spindle lock. In order to machine a tool holder in a balancing machine, the spindle unit must be locked to prevent damage to the spindle mount or even the sensor system. For this purpose, US 2012 / 0 279 286 A1 proposes a first and a second clamping jaw unit, with clamping strips that are elastic in a direction perpendicular to the spindle's rotational axis and perpendicular to the measuring direction of the sensor device. The sensor device is integrated into the spindle mount. The spindle unit is attached to the machine base by means of the spindle mount, which is detachably attached to the spindle holder, and not to a damper system.

[0011] The invention is based on the object of providing a device with which movements or forces of a rotating shaft can be transmitted to a damper unit.

[0012] The problem is solved by the features of claim 1. Preferred embodiments are described in the dependent claims.

[0013] The object is achieved according to the invention in that a coupling device for coupling a damper unit to a rotatable shaft is provided, which can be attached between the shaft and the damper unit, with a first yoke on the shaft and a second yoke parallel to the first and fixable to the damper unit, and with at least two spiral springs arranged parallel to one another between the first and second yoke, the free ends of which are each connected to the first and second yoke, so that the two yokes, together with the spiral springs, form a parallelogram. Due to the inventive design of the coupling device, movements or forces of a rotatable shaft can be transmitted to a damper unit without causing damage to the coupling device, for example due to twisting of the springs.In addition, it is possible to subject rotors with high imbalances to a setting process without causing damage to the spin test bench.

[0014] In the sense of the invention, a damper unit can be, in particular, a linear actuator, such as, but not limited to, an oil, air or other fluid damper, a spring, a gas spring, an active actuator for controlled vibration compensation or combinations thereof.

[0015] It is preferred that the first and second yokes comprise a first and a second side, with connecting means for connecting to a shaft bearing being provided on the first side of the first yoke and connecting means for connecting to the damper unit being provided on the first side of the second yoke. Depending on the application, the connecting means can be designed in various ways. For example, screw connections via a flange or material-to-material connections may be advantageous.

[0016] In one embodiment, the spiral springs are designed as leaf springs or round bar springs. Advantageously, the spiral springs are designed to be as soft as possible to keep the restoring force as low as possible.

[0017] The spiral springs advantageously engage with their free ends near the outer ends of the yokes. The springs can be attached to the respective yoke via known connecting means. The yoke can also have spring plates to accommodate a spring, in which the free end of each spring is supported. The invention further relates to a damper system for damping rotary movements performed by a shaft, comprising at least two damper units and two coupling devices as previously explained, which can be attached between the shaft and a respective damper unit. Each coupling device is operatively connected to a first yoke via a bearing to the shaft and a second yoke parallel to the first to the damper unit, so that forces and movements exerted by the shaft on the coupling devices can be transmitted to the damper units. The damper system is versatile and can be used to stabilize a flexible shaft.The coupling devices achieve a particularly backlash-free transmission of force and displacement between the shaft and the damper units, so that the shaft's rotary movements are converted into linear movements that can be damped by linear damper units. For this purpose, the coupling devices advantageously engage the shaft bearing, in particular the bearing outer ring, which is preferably designed as a backlash-free bearing. A backlash-free bearing can prevent discontinuities.

[0018] It has proven advantageous if the coupling devices are arranged in a plane running radially to the shaft or its longitudinal axis. If necessary, more than two damper units and consequently coupling devices can be used, with one coupling device being provided for each damper unit. By arranging the coupling devices in one plane, the rotary movements of the shaft can be efficiently coupled. It can be provided to arrange several coupling devices and consequently damper units one above the other in several planes lying radially to the shaft. It has proven particularly advantageous if the coupling devices are at an angle of 90° to one another in the respective plane. This allows movements of the shaft in the x and y directions to be recorded.Furthermore, the invention relates to a spin test rig with a damper system as described above and a mount for a rotor to be tested, so that forces and movements exerted by the shaft on the coupling devices can be transmitted to the damper units. A spin test rig designed in this way can also be used to test test specimens with high levels of unbalance. Due to the efficient damping of the damper system, prior unbalance correction is not necessarily required.

[0019] The invention will be explained in more detail below with reference to an embodiment of the invention, which is illustrated in the drawing.

[0020] Figure 1 is a schematic representation of a spin test bench according to the state of the art and

[0021] Figure 2 is a schematic representation of damping of a rotating shaft.

[0022] Figure 1 shows a schematic representation of a vertical spin test rig according to the prior art. In addition to a housing (not shown), the spin test rig 1 comprises a drive 2 for supplying torque. The drive 2 can be configured, for example, as an electric motor. The torque of the drive 2 is transmitted to a vertically extending shaft 3 by connecting the shaft 3 on the drive side to the drive 2 via a bearing element 4 in a torque-transmitting manner. The bearing element 4 can be configured, for example, as a bearing, coupling, or the like, into which the shaft journal of the shaft 3 engages.

[0023] The rotor-side end of the shaft 3 opposite the drive 2 is connected to a rotor 5 to be tested in a torque-transmitting manner. The rotor 5 is accommodated in a clamping fixture 6 and clamped in a rotationally fixed manner. The clamping fixture 6 can be constructed differently depending on the shape and structure of the rotor 5. An interchangeable clamping fixture 6 is advantageous here, so that the clamping fixture 6 can be changed depending on the test object. The clamping fixture 6 can be connected to the shaft 3 in a rotationally fixed manner via a flange connection.

[0024] A schematically illustrated damper unit 7 is arranged on the shaft 3 between the bearing element 4 and the clamping fixture 6. It is operatively connected to the shaft 3 by means of a fixed housing. Rotation of the rotor 5 imparts an oscillating excitation movement to be damped to the shaft 3, which leads to vibrations of the shaft 3 in the direction of the rotation radius.

[0025] Due to the design of the spin test rig 1, the rotational axis of the rotor 5 being tested is not fixed. Due to its essentially freely suspended bearings, the rotor 5 can move in such a way that it can freely choose its rotational axis. This means that unbalanced rotors 5 can rotate around their mass axis of inertia instead of their geometric axis, which essentially results in no unbalance forces. Larger imbalances can lead to damage due to stresses and forces in the shaft 3 and the clamping fixture 6.

[0026] To stabilize the shaft in the spin test bench 1, a damper system can be provided, as indicated in Figure 2. It should be noted that the use of the damper system is not limited to a spin test bench 1. Rather, its functionality will be illustrated using a spin test bench 1.

[0027] The damper system comprises at least two coupling devices 8 that operatively connect two damper units 7 to the shaft 3. Depending on the application, more damper units 7 can be used, each of which can be connected to the shaft 3 via a coupling device 8. The following explains the structure of a coupling device 8 as an example, with at least two damper units 7 and consequently at least two coupling devices 8 being provided for the damper system according to the invention.

[0028] A coupling device 8 is installed between each shaft 3 and a respective damper unit 7. The coupling device 8 comprises two yokes arranged at a distance from one another, namely a first yoke 9 near the shaft and a second yoke 10 near the damper. The first yoke 9 can be fixed to the shaft 3, more precisely to a shaft bearing 11, or to an outer bearing ring of the bearing 11, and the second yoke can be fixed to the damper unit 7. In particular, the second yoke 10 engages an operating mechanism of the damper unit 8, such as a piston. The first yoke 9 is arranged parallel to the second yoke 10.

[0029] Each yoke 9, 10 comprises a first and a second side, with connecting means on the first side for connecting the first yoke 9 near the shaft to the shaft bearing 11 and the second yoke 10 near the damper to the damper unit 7. The connecting means can be designed, for example, as screw connections. The yokes 9, 10 are preferably made of metal, but can also be made of plastic, a fiber-reinforced plastic, or combinations thereof.

[0030] Between the first and second yokes 9, 10 are two parallel spiral springs 12. On the second side of the respective yoke 9, 10, opposite the first side, there are means for attaching at least two spiral springs 12. These means can be designed, for example, as spring plates. At least two spiral springs 12 are provided in a preferred embodiment of the coupling device. However, more spiral springs 12 can also be attached.

[0031] The bending springs 12 are arranged near or at the outer ends of the yokes 9, 10.

[0032] The bending springs 12 can, for example, be designed as round bar springs.

[0033] The spiral springs 12 are preferably designed to be flexible. It is preferred that the spiral springs 12 be designed such that they do not exhibit resonance phenomena within a targeted speed range and that no buckling of the spiral springs 12 occurs due to the transmitted damping. Furthermore, the spiral springs 12 can have constrictions, for example, two or more constrictions. This has the advantage that any pitching movements of the shaft 3 are not hindered. The unit comprising the two spiral springs 12 and the first and second yokes 9, 10 can be connected to one another in such a way that the spiral springs 12 are replaceable as needed. For example, depending on the rotor mass, coupling devices 8 with appropriately dimensioned spiral springs 12 can be used, which can be easily replaced.

[0034] The coupling devices 8 are preferably arranged in a plane extending substantially radially from the shaft 3, wherein the two coupling devices 8 are at an angle of 90° to each other.

[0035] When the shaft 3 moves, for example, in the x-direction, the movement and the force are transmitted from the horizontally illustrated coupling device 8 to the damper unit 7. The vertically illustrated damper unit 7 experiences neither a force nor a movement in the y-direction, since the intermediate and vertically illustrated coupling device 8 compensates for the offset between the damper unit 7 and the shaft 3 by deflecting the spiral springs 12. The coupling device 8 deforms due to its parallelogram design. Due to an advantageous design of the flexible spiral springs 12, any spring restoring force is minimal.

[0036] Due to the advantageous design of the coupling device 8 as a parallelogram, the two yokes 9, 10 of the coupling device 8 remain parallel to each other, and the yokes 9, which are connected to the bearing 11, do not rotate (direction of rotation shown as "z"). As a result, the coupling is essentially resonance-free within a desired speed range, despite any soft-tuned spiral springs 12 in the direction of rotation, and can support the torque through bearing friction. Damage to the yokes 9, 10 is prevented.

[0037] The invention can also simplify the setting process for rotors 5 with high imbalance. Occasionally, rotors 5 must be centrifuged at high speeds (up to approximately 30,000 rpm) at the end of the manufacturing process so that the individual rotor components are seated together due to centrifugal force. After this setting process, a final balancing process takes place in which any existing imbalance in the rotor 5 is compensated. However, if the rotors 5 already exhibit excessive imbalance prior to the setting process, the imbalance may cause damage to the spin test rig. To prevent this, unbalance compensation can be performed prior to the setting process; however, this does not eliminate the need for unbalance compensation after the actual setting process. The invention makes it possible to achieve efficient damping of a shaft moving along a circular path by converting the shaft's movements into dampable linear movements.This means that even rotors 5 with a high imbalance can be spun in one setting process without prior imbalance compensation.

Claims

PATENT CLAIMS 1. Coupling device (8) for coupling a damper unit (7) to a rotatable shaft (3), which can be attached between the shaft (3) and the damper unit (7), with a first yoke (9, 10) on the shaft (3) and a second yoke (9, 10) which is parallel to the first and can be fixed to the damper unit (7), and with at least two spiral springs (12) arranged parallel to one another between the first and second yokes (9, 10), the free ends of which are each connected to the first and second yokes (9, 10), so that the two yokes (9, 10) together with the spiral springs (12) form a parallelogram.

2. Coupling device (8) according to claim 1, characterized in that the first and the second yoke (9, 10) comprise a first and a second side, wherein on the first side of the first yoke (9) there are connecting means for connection to a shaft bearing (11) and on the first side of the second yoke (10) there are connecting means for connection to the damper unit (7).

3. Coupling device (8) according to claim 1 or 2, characterized in that the bending springs (12) are designed as leaf springs or as round bar springs.

4. Coupling device (8) according to one of the preceding claims, characterized in that the spiral springs (12) engage with their free ends near the outer ends of the yokes (9, 10).

5. Damper system for damping rotary movements performed by a shaft (3) with at least two damper units (7) and two coupling devices (8) according to one of the preceding claims, which can be mounted between the shaft (3) and a respective damper unit (7), wherein each coupling device (8) is provided with a first Yoke (9) is operatively connected to the shaft (3) via a bearing (11) and to a second yoke (10) parallel to the first with the damper unit (7), so that forces and movements exerted by the shaft (3) on the coupling devices (8) can be transmitted to the damper units (7).

6. Damper system according to claim 5, characterized in that the bearing (11) is designed as a play-free bearing (11).

7. Damper system according to claim 5 or 6, characterized in that the coupling devices (8) are arranged in a plane extending radially to the shaft (3).

8. Damper system according to claim 7, characterized in that the coupling devices (8) are at an angle of 90° to one another in the plane.

9. Centrifugal test bench (1) with a damper system according to claims 5-8 and a holder (6) for a rotor (5) to be tested, so that forces and movements exerted by the shaft (3) on the coupling devices (8) can be transmitted to the damper units (7).

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