Abstract:
Gear wheel and method for reducing vibrations transmitted by a rotating shaft. The gear wheel includes an inner part, which is connectable to a cause of vibration, a connection element and a ring gear. The connection element is structured and arranged to reduce vibrations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority under 35 U.S.C. §119(a) of German Patent Application No. 10 2012 001 703.0 filed Jan. 31, 2012, the disclosure which is expressly incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the invention relate to a gear wheel and in particular a gear wheel which includes several components. The gear wheel according to embodiments of the invention can be used particularly advantageously in connection with stepper motors on satellites. However, use of the gear wheel is not limited to this field of application, but can be used advantageously in any arrangement or assembly in which the influence of vibrations, in particular micro-vibrations, should or has to be reduced or minimized. 
         [0004]    2. Discussion of Background Information 
         [0005]    With the use of stepper motors in arrangements or assemblies, micro-vibrations (micro jitter) are caused by the cogging torque of the rotor. These micro-vibrations are transmitted to the structural parts of the arrangement or the assembly. This leads for example to disturbances in the arrangement or assembly in particular in the instruments thereof or to directing errors. The micro-vibrations are produced for example by permanent magnets in the rotating part of the motor and transmitted as accelerations via the gear wheel to the arrangement or assembly. 
       SUMMARY OF THE EMBODIMENTS 
       [0006]    Embodiments of the invention provide a gear wheel structured so that the effects of vibrations, in particular of micro-vibrations, are reduced. 
         [0007]    According to embodiments, the gear wheel includes an inner part, which is connected to a cause of vibrations, a connection element and a ring gear. The connection element is embodied or formed so that the vibrations caused are reduced. 
         [0008]    The gear wheel according to embodiments includes an inner part, which is connected to a causer or source of vibrations, in particular micro-vibrations, e.g., a drive shaft of a motor, in particular a stepper motor on a satellite, a connection element and a ring gear. The connection element is embodied or formed so that the vibrations, in particular micro-vibrations, caused are reduced. To this end in particular, the connection element can be connected to the inner part of the gear wheel and the ring gear in a non-positive manner. The invention advantageously reduces vibrations, in particular micro-vibrations, which act on the ring gear. 
         [0009]    According to embodiments, the connection element of the gear wheel can be embodied or formed as a spring sheet. It is particularly advantageous when the spring sheet is produced from aluminum, titanium or spring steel. It is furthermore particularly advantageous when the spring sheet has a thickness of at least 0.1 mm. 
         [0010]    According to further embodiments, the connection element of the gear wheel can be embodied or formed as a cast plastic ring. It is particularly advantageous when the plastic ring is produced from an elastic synthetic material, e.g., RTV plastic, silicone or a resin system. It is furthermore particularly advantageous if the plastic ring has a thickness of at least 1/10 mm to several millimeters. 
         [0011]    Embodiments of the invention are directed to a gear wheel that includes an inner part, which is connectable to a cause of vibration, a connection element and a ring gear. The connection element is structured and arranged to reduce vibrations. 
         [0012]    According to embodiments of the invention, the connection element can be coupled to the inner part and to the ring gear in a non-positive manner. 
         [0013]    In accordance with embodiments, the connection element can be structured and arranged as a spring sheet. The spring sheet may include at least one of aluminum, titanium and spring steel. Further, the spring sheet can have a thickness of at least 0.1 mm. 
         [0014]    Moreover, the connection element may include a cast plastic ring. The plastic ring can include elastic synthetic material. The elastic synthetic material may include at least one of RTV plastic, silicone and a resin system. Further, the plastic ring can have a thickness of at least 1/10 mm. 
         [0015]    In embodiments, the inner part can be connectable to a motor via a drive shaft. The motor can be a stepper motor on a satellite. 
         [0016]    According to other embodiments, the vibrations can be micro-vibrations and the cause of the vibrations can be a motor of a satellite. 
         [0017]    Embodiments of the invention are directed to a gear wheel for connection to a vibrating shaft of a motor. The gear wheel includes an inner part coupleable to the vibrating shaft, a ring gear surrounding the inner part and a connection element structured and arranged to couple the inner part to the ring gear so as to reduce an amplitude of vibrations in the vibrating shaft transmitted to the ring gear. 
         [0018]    According to embodiments, the vibrations in the vibrating shaft may be micro-vibrations. 
         [0019]    In accordance with other embodiments, the motor can be structured for use in a satellite. 
         [0020]    According to still other embodiments, the motor may include a stepper motor in a satellite. 
         [0021]    In further embodiments, the connection element can have a radial thickness of about 0.1 mm and may include one of spring sheet and a cast plastic ring. Moreover, when the connection element is spring sheet, the spring sheet can include at least one of aluminum, titanium and spring steel. When the connection element is a cast plastic ring, the cast plastic ring can include at least one of RTV plastic, silicone and a resin system. 
         [0022]    Embodiments of the invention are directed to a method for reducing vibrations transmitted by a rotating shaft. The method includes connecting a gear wheel to the rotating shaft, the gear wheel having a vibration damping element coupling an inner part for connection to the rotating shaft to a ring gear separated from the inner part. 
         [0023]    In accordance with still yet other embodiments of the present invention, the vibrations transmitted by the rotating shaft can be micro-vibrations in a satellite. 
         [0024]    Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein: 
           [0026]      FIG. 1  illustrates an embodiment of the gear wheel including a plastic ring; and 
           [0027]      FIG. 2  illustrates an embodiment of the gear wheel including spring sheet. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0028]    The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied or formed in practice. 
         [0029]      FIG. 1  shows an embodiment of the gear wheel. According to the embodiment, the gear wheel can include three parts, i.e., an inner part ( 1 ) of the gear wheel, a connection element ( 2 ) of the gear wheel and a ring gear ( 3 ) of the gear wheel. 
         [0030]    The inner part ( 1 ) of the gear wheel can be embodied or formed so that it can be connected, e.g., to a motor via a drive shaft. The motor and/or the drive shaft identified are merely exemplary possible devices or elements causing or acting as sources for vibrations, and more particularly for micro-vibrations. However, it is understood that any number of devices causing or acting as sources for vibrations and/or micro-vibrations are known and can be associated with the exemplary gear wheel without departing from the spirit and scope of the embodiments. Thus, it is understood that the embodiments of the invention can likewise be applied and used in combination with such other causes or sources of vibrations, in particular micro-vibrations. 
         [0031]    The connection element ( 2 ) is embodied or formed such that the vibrations, in particular micro-vibrations, which are caused, e.g., by the drive shaft of the motor and act on the ring gear ( 3 ), are reduced by the reduced stiffness (inertia of the system). To this end, the connection element ( 2 ) according to the invention is connected to the inner part ( 1 ) and the ring gear ( 3 ) in a non-positive manner. The reduction factor achieved thereby depends on the thickness and the stiffness of the connection element ( 2 ). 
         [0032]    According to the embodiments, the stiffness of the connection element ( 2 ), which can be embodied or formed, e.g., as individual sheets or ring, can be of particular significance. 
         [0033]    According to the embodiment in  FIG. 1 , the connection element ( 2 ) of the gear wheel is embodied or formed as a cast plastic ring. The plastic ring serves as a force transmission element. According to the invention, it is particularly advantageous if the plastic ring is produced from an elastic synthetic material, e.g., RTV plastic (RTV-S=961) silicone or resin systems. For advantageous reduction properties, the thickness of the plastic ring should be between 1/10 mm up to several millimeters. 
         [0034]    It is a technical advantage of this embodiment that the amplitude of the vibrations, in particular micro-vibrations, is reduced to a lower level. By way of example, ten times lower amplitudes are achieved as compared to the case without the plastic ring. In this way, the effect of the vibrations, in particular micro-vibrations, of the motor on instruments of a device, e.g., of a satellite, and on the device can thus be minimized. 
         [0035]    According to the embodiment in  FIG. 2 , the connection element of the gear wheel ( 2 ) is embodied or formed as a spring sheet. The spring sheet serves as a force-transmitting element. By way of example, connection element ( 2 ) can be milled out of the gear wheel or inserted into grooves. According to the embodiments, it is particularly advantageous if the spring sheet is produced from aluminum, titanium or spring steel. For advantageous oscillation properties, the thickness of the spring sheet should be at least 0.1 mm. 
         [0036]    A technical advantage of this embodiment is that the amplitude of vibrations, in particular micro-vibrations, is reduced to a lower level. For example, ten times lower amplitudes are achieved as compared to the case without spring sheet. The effect of the vibrations, in particular micro-vibrations, of the motor on instruments of a device, e.g., a satellite and on the device can thus be minimized. 
         [0037]    It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.