Torque Transmission Device

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS [0001] This patent application claims the benefit of German patent application 10 2005 004 819.6 filed February 1, 2005, German patent application 10 2005 004 821.8 filed February 1, 2005, German patent application 10 2005 004 822.6 filed February 1, 2005, German patent application 10 2005 004 823.4 filed February 1, 2005, German patent application 10 2005 027 631.8 filed June 14, 2005, and German patent application 10 2005 039 428.0 filed August 18, 2005, the disclosures of which are incorporated in their entirety herein by reference.

FIELD OF THE INVENTION

[0002] This invention pertains generally to a torque transmission device, and more particularly to a device for transferring torque from a constant angular velocity driveshaft to another shaft, which may vary in angular velocity.

BACKGROUND OF THE INVENTION

[0003] In many mechanical devices it is necessary to transmit torque or rotational movement from one shaft to another. As known in the art, one simple way transmit torque from one shaft to another is by a rigid connection of the two shafts. However, a rigid connection of rotating shafts constrains both shafts to, somewhat disadvantageously, have the same angular velocity. For a static system constantly operating at the same angular velocity, rigid connection of rotating shafts is acceptable. However, problems arise with using a rigid connection of shafts when the angular velocity of the system varies dynamically, due to, for example, a disturbance by external influences.

[0004] Various mechanisms such as transmissions are known for transferring torque or rotational movement from one shaft to another without a rigid connection of the two shafts. However, a torque transmission device with reliable operation and a more efficient transfer of torque from the driveshaft to the output shaft would be a significant improvement in the art.

Furthermore, an improved torque transmission device that compensates for differences between the angular velocities of two shafts in a short time would be welcomed.

BRIEF SUMMARY OF THE INVENTION

[0005] The present invention provides a torque transmission device comprising at least one lever system and at least one preload force device interacting with said lever system in order that torque is transmitted from one shaft to another. In one embodiment the device includes: a preload force device extending radially from the driveshaft, the preload force device including a proximal end affixed to the first shaft and a distal end; a lever extending radially from the first shaft, the lever including a proximal end in communication with the first shaft, a distal end coupled with the distal end of the preload force device, and a fulcrum intermediate the proximal and distal ends; and an arm including a proximal end affixed to the second shaft and a distal end coupled to the fulcrum, wherein the lever is configured to rotate on the arm about the fulcrum.

BRIEF DESCRIPTION OF THE DRAWINGS [0006] FIG. 1 shows a side view of an embodiment of a torque transmission device according to the present invention;

[0007] FIG. 2 shows an end view of a portion of the device of FIG. 1, illustrating operation thereof; and

[0008] Fig. 3 illustrates another embodiment of the present invention in which a stator of an electric motor is driven by another motor.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0009] Referring now to FIGS. 1-3, a torque transmission device is described. As shown in FIG. 1, a driveshaft 1 is coupled by an embodiment of the subject torque transmission device to an output shaft 2. The driveshaft 1 may be made of steel or any other suitable material for bearing an imposed load coupled thereto. The driveshaft 1 may be driven by a rotational actuator such as a motor (not shown) that is powered by electricity, steam or any other suitable energy source known in the art. The motor applies a torque to the driveshaft 1 for rotating a load. The torque of driveshaft 1 is intended to be transmitted to an output shaft 2, which may be made of steel or any other suitable material.

The output shaft 2 may be integral with or separate from a device (e.g., a generator) that is to be driven by driveshaft 1

[0010] In the embodiment of the present invention depicted in FIG. 1 the driveshaft 1 is reduced in diameter at its end adjacent to the output shaft 2 (i.e., the end distal from the motor). Thus, the driveshaft 1 is configured at its end to support a bearing (e.g., bearing cone or the like) within a hollow portion of the output shaft 2. This illustrated configuration of the driveshaft 1 and output shaft 2 is by no means limiting and the driveshaft 1 and output shaft 2 may be configured otherwise. Furthermore, a person of ordinary skill in the pertinent arts will appreciate that the support of the shafts 1, 2 at their adjacent ends can also be provided by a housing. In this case the aligning or centring of the shafts 1, 2 could be accomplished by using collars connected to the shafts 1, 2 at their adjacent ends.

[0011] As best illustrated in FIG. 1, the subject device for transmitting torque from the driveshaft 1 to the output shaft 2 includes at least one lever system and at least one preload force device interacting with the lever system. As shown, the at least one lever system includes two lever systems comprising first lever system including elements 3 and 4, and second lever system including elements 5 and 6. Although two lever systems are illustrated, fewer or additional lever systems may be provided.

[0012] As shown, the first lever system comprises an extension arm 4 and a lever 3. Similarly, the second lever system comprises an extension arm 6 and a lever 4. As shown, the first and second lever systems are substantially similar, however, the first and second lever systems are not limited to being substantially similar. The embodiment illustrated in FIGS. 1 and 2 shows the two lever systems (i.e., first lever system 3, 4 and second lever system 5, 6) arranged to be diametrically opposing, that is, oriented approximately 180 degrees apart from each other with respect to a central axis through the shafts 1, 2.

However, the two lever systems are not limited to being separated by approximately 180 degrees as shown. For example, if four lever systems were employed, adjacent lever systems could be separated by approximate 90 degree angles. The number of the used lever systems is neither restricted to a certain amount nor a certain range. In some embodiments it is preferable to a have a symmetric arrangement of the lever systems.

[0013] As shown, the extension arms 4, 6 are generally L-shaped with a long side and a short side. However, the extension arms 4, 6 may have any other suitable shape (e.g., polylinear, curvilinear, etc.) that permits rotation or pivoting of the lever 3, 5 about its connection point (i.e., fulcrum) with the respective extension arms 4, 6. The levers 3, 5 and the extension arms 4, 6 may be made from steel or any other suitable material to bear the imposed load. In some embodiments of the device, the cross-sectional form of the levers 3, 5 is rectangular while the extension arms 4, 6 have a circular or rectangular cross- sectional form. The levers 3, 5 or the extension arms 4, 6 may be made of various solid bars or hollow pipes with appropriate cross-sectional forms (e.g., round, square, rectangular, etc.) as known in the art.

[0014] Referring to the example embodiment shown in Fig. 1, the long sides of extension arms 4, 6 are joined to the output shaft 2 so that the extension arms 4, 6 rotate with the output shaft 2. The ends of the long sides of the extension arms 4, 6 may be affixed to the output shaft 2 by welding, but any other suitable fastening method or mechanism (e.g., use of a shaft to collar connection) may be employed.

[0015] The ends of short sides of extension arms 4, 6 are coupled to the levers 3, 5. The coupling of extension arms 4, 6 to the levers 3, 5 defines fulcrums dividing each of the levers 3, 5 so that the levers 3, 5 are free to pivot, tilt or rotate about the short sides of extension arms 4, 6 like a see-saw in a plane perpendicular to the output shaft 2. The fulcrum, which couples the extension arms 4, 6 and the levers 3, 5, in some embodiments can include a bearing or the like, but in other embodiments the fulcrum may comprise a pin sleeve or other mechanical fastening that allows rotation of one object with respect to another.

[0016] As previously mentioned, each of the levers 3, 5 is divided into two portions by the fulcrums. The ratio of the lengths of the lever portions in some embodiments may be 2:1 with the shorter portion being adjacent to the shafts 1, 2. However a 2:1 ratio of the lever portion lengths is by no means required. Indeed, the fulcrums may be configured on the levers 3, 5 to provide other ratios as desired. For example, as shown in FIG. 1, the extension arms 4, 6 may be coupled to the levers 3, 5 to give a ratio of about 1:1. Since the ratio influences the magnitude of a necessary preload force (i.e., F3, F4 of FIG. 2), which will be discussed hereinafter, it is desirable in some embodiments of the device to

choose the length of the portion of levers 3, 5 adjacent to the shafts 1, 2 to be considerably smaller than the distal portion of the levers 3, 6.

[0017] As best illustrated in FIGS. 1 and 2, during the transmission of torque, the innermost ends of the levers 3, 5 are in contact with the driveshaft 1 such that the forces Fl, F2 are exerted on the innermost ends of the levers 3, 5. The contact areas 9, 10 where the levers 3, 5 are in contact with the driveshaft 1 may be formed as protrusions from the surface of the driveshaft 1. These protrusions 9, 10 may have a generally quarter-circular or triangular shape with one surface being substantially perpendicular to the driveshaft' s surface for contacting the ends of the levers 3, 5. Of course the protrusions 9, 10 may be configured otherwise on the driveshaft 1 for contacting the levers 3, 5. For example, in other embodiments the contact areas 9, 10 may be configured to be substantially linear or planar (e.g., fins) and extend from the surface of the driveshaft 1. As known in the art, the contact areas 9, 10 may be integral with the driveshaft 1 or otherwise attached to the driveshaft 1, for example by welding the contact areas 9, 10 to the driveshaft's surface.

[0018] When driveshaft 1 rotates in a clockwise direction as shown in FIG. 2, the forces Fl, F2 that are exerted on the lever's innermost end by the contact areas 9, 10 would cause the levers 3, 5 to rotate about the extension arms 4, 6 if no reverse force held the levers 3, 5 in position. For this purpose, preload force devices 7, 8 (FIG. 1) are provided to maintain contact between the levers 3, 5 and the contact areas 9, 10 on the driveshaft 1. The preload force devices 7, 8 comprise devices that are configured with a bias to exert a force after being pre-stressed. Example preload force devices for use with the present device include a pre-stressed spring or a pre-stressed torsion rod.

[0019] In the illustrated embodiment depicted in Fig. 1, the preload force devices 7, 8 comprise pre-stressed torsion rods, which may be made of steel. The pre-stressed torsion rods 7, 8 at one end include a flange such that it can be attached to the driveshaft 1, for example, by means of screwing the flange to the driveshaft 1 so that which the pre-stressed torsion rods 7, 8 are aligned with the respective first and second lever systems 3, 4 and 5, 6. At the opposite end of the pre-stressed torsion rods 7, 8 a metal plate may be welded to the pre-stressed torsion rods 7, 8 in such a way that the metal plate contacts the outermost ends of the levers 3, 5 so that the preload forces F3, F4 are exerted on the levers 3, 5.

[0020] The preload forces F3, F4 act in the same direction as the respective forces Fl, F2 exerted on the levers 3, 5 by the contact areas 9, 10 and is needed to compensate the forces Fl, F2 to maintain the levers 3, 5 in contact with the driveshaft 1, thus allowing the transmission of torque from the driveshaft 1 to the output shaft 2. Therefore, as can be appreciated, the maximum amount of torque transmittable from driveshaft 1 to output shaft 2 by a lever system 3, 4 or 5, 6 with a certain ratio (e.g., 2:1, 1:1, etc.) of the lever portions is limited by the magnitude of the preload force F3, F4.

[0021] As shown in FIG. 1, further extension arms 11, 12, which may be similar to the extension arms 4, 6, can be joined at their longer sides to the outermost end of the extension arms 4, 6 such that the shorter end of the further extension arms 11, 12 supports the outermost ends of the levers 3, 5 when the levers 3, 5 are in the positions for transmitting torque, but still allowing said levers 3, 5 to rotate in the direction opposite to the shafts 1, 2. The joining of the further extension arms 11, 12 to the respective extension arms 4, 6 may be done by mechanical fastening, welding or the like.

[0022] In order to further describe the operation of a torque transmission device according to the present invention, the transmission of torque from the driveshaft 1 to the output shaft 2 will be described in detail as follows. In order to avoid duplication, the torque transmission will be described with reference to the upper lever system 3, 4 shown in figures 1 and 2. It however should be emphasized that torque will also be transmitted in the same manner through the lower lever system 5, 6.

[0023] The torque applied by a motor to the driveshaft 1 is distributed to the lever system 3, 4 by the fact that the driveshaft 1 exerts the force Fl on lever 3 at the contact area 9. Because the force Fl would cause the lever 3 to deflect (i.e., rotate or pivot counter clockwise about the fulcrum where extension arm 4 couples with lever 3), the force F3 is exerted on the opposite end of lever 3 by the preload force device 7 in order to keep lever 3 in contact with the contact area 9 of driveshaft 1. The resultant of the forces including Fl and F3 being applied to lever 3 act on the lever's fulcrum at the extension arm 4. The extension arm 4 is joined to the output shaft 2 such that the force acting on the extension arm 4 applies a torque to the output shaft 2.

[0024] It should be appreciated that the arrangement of the lever system 3, 4 or 5, 6 on the output shaft 2 and the preload force device 7 or 8 on the driveshaft 1 can be reversed

with respect to the shafts 1, 2 without degrading the functionality of a torque transmission device according to the present invention.

[0025] Since the lever systems 3, 4 or 5, 6 and the preload force device 7 or 8 interact on the principle of a see-saw, those of ordinary skill in the pertinent arts will appreciate that a torque transmission device according to the present invention is flexible with respect to the angular velocities of the shafts 1, 2 and therefore can compensate dynamically for short-time (i.e., momentary) differences in the angular velocities of the shafts 1 and 2.

[0026] In another embodiment, a torque transmission device according to the present invention may be part of or used in cooperation with a brake (e.g., an eddy-current brake, not shown). For example, a brake acting on the output shaft 2 may cause differences between angular velocities of the shafts 1 and 2 and the torque transmission device may be used to ensure a smooth operation of the brake by causing the shafts 1, 2 to have the same angular velocity. Differences in the angular velocities of the shafts 1, 2 can occur when, for example, the electrical load on a generator connected to the output shaft 2 varies due to fluctuations in the energy consumption of the device being fed by the generator, while the motor driving the driveshaft 1 operates constantly at the operating point of maximum efficiency. Use of the present torque transmission device allows for operation of the motor driving the driveshaft 1 substantially constantly at the operating point of maximum efficiency to not only reduce the "wear and tear" on the electric motor, but also leads to an overall more efficient transfer of energy between the motor and generator.

[0027] In a further embodiment of the present invention, schematically depicted in FIG. 3, the output shaft 2 is coupled with an electric motor to drive its stator 13. The rotation of the rotor 14 of the electric motor is then compensated by the rotation of the stator 13 driven by the output shaft 2 in the opposite direction. According to this embodiment, an improved electric motor is provided such that the relative rotation of the rotor 14 and the stator 13 increase the performance of the electric motor.

[0028] Alternatively, it is also envisioned that instead of driving the stator 13 in addition to the rotor 14, an electric motor may be provided in which the rotor 14 is connected to and driven by the output shaft 2. The electric motor may then be used to drive a generator or at least compensate the existing drive unit of a generator.

[0029] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0030] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non- claimed element as essential to the practice of the invention.

[0031] Various embodiments of this invention are described herein. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.