Patent Publication Number: US-2010129153-A1

Title: Vibration reducing link for vibrating screed

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority, under 35 U.S.C. § 119(e), on U.S. provisional patent application serial No. 61/118,033, filed on Nov. 26, 2008, which is incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a vibration dampening handlebar link. More specifically, the present invention is concerned with a vibration reducing link for vibrating screed. 
     BACKGROUND OF THE INVENTION 
     Known in the art, there are vibrating screeds including, for instance, an elongated blade extending horizontally and transversally at lower ends of a pair of handles adapted to be hand held and operated for displacing the screed over a concrete surface. A motor is provided above the blade and between the handles and has its shaft extending vertically downwards from the motor to the blade and is connected thereat such that, with a counterweight or a cam-like arrangement, it imparts oscillatory movement to the blade of high frequency but low amplitude. 
     Generally, such devices are guided and controlled by a pair of handlebars to be gripped by an operator to permit easy and constant correction of the level of the concrete with minimum effort. For example, U.S. Pat. No. 6,296,467 (Rouillard) discloses a handlebar with textured rubber grip members attached thereto. Furthermore, the screed has adjustable handles including a main elongated handle member. Each handle has a first element mounted to a proximal end of the main handle member. The handle has second and third elements capable of relative rotatable displacement and capable of being secured in a desired relative position thereof with a grip member being mounted to the third element such that the grip member may be swiveled at least partly around an axis of the second element. 
     However, the operation of such devices usually occurs over many hours during which period vibrations from the oscillatory movement of the blade will be transferred to the operator through the handles means leading to increased operator fatigue. 
     While the prior art teaches of vibration isolators which act to reduce the vibration produced by a vibration exciter mechanism, such vibration reducing isolators are located near the vibration exciter mechanism itself and away from the operator handles. 
     The Applicant has discovered that even with such vibrating reducing isolators located near the vibration exciter mechanism, there are still substantial remaining oscillatory movements transferred to the operator. There is therefore a need for a solution to this problem of vibrations felt by the user when grasping handlebar grip members of vibrating screed. 
     SUMMARY OF THE INVENTION 
     More specifically, in accordance with the present invention, there is provided vibrating screed comprising:
         a surfacing blade;   a vibration-causing assembly in communication with the surfacing blade;   a steering assembly in communication with the surfacing blade, the steering assembly comprising a handle assembly;   a grip member in communication with the handle assembly; and   a vibration reducing link disposed between the grip member and the handle assembly;
 
wherein when the vibration-causing assembly imparts a vibratory motion to the blade and the handle assembly, the vibration reducing link dampens the vibratory motion transmitted between the handle assembly and the grip member.
       

     Preferably, the reducing link comprises: a first member in communication with the handle assembly; a vibration reducing coupling disposed circumferentially about the first member; a second member in communication with the grip, the second member receiving the vibration reducing coupling and the first tubular member; and a clamp for securing the first tubular members and the vibration reducing coupling within the second tubular members when received therein; wherein the vibration reducing coupling dampens vibration transmitted between the first and second members. 
     Preferably, the vibration reducing coupling is disposed circumferentially within the second member, the first member received within the vibration reducing coupling and the second member. 
     Preferably, the first member and the vibration reducing coupling are rotatable within the second member. 
     Preferably, the vibration reducing coupling has a non-elastomeric layer disposed circumferentially about the vibration reducing coupling. 
     Preferably, the vibration reducing link includes a coupling made of elastomeric material such as vulcanized rubber to couple handlebar members in order to dampen vibration and shock. 
     Preferably, the first member in substantially perpendicular in communication to the handle assembly, the second member is substantially perpendicular in communication to the first member. 
     Preferably, the clamp is circumferentially disposed about the second member. 
     Advantageously, compared to prior art screed, the present invention localizes vibration isolators closer to the handles such that the remaining vibrations not suppressed by the isolators located closer to the vibration exciter mechanisms are further and substantially reduced. 
     Another advantage of the present invention over the prior art involves the capability of easily retrofitting the vibration reducing link to the handle assemblies of existing screeds. 
     Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the appended drawings: 
         FIG. 1  is a perspective view of a handlebar assembly for vibrating screed incorporating a vibration reducing link used to couple handlebar assembly elements; 
         FIG. 2  is a perspective view of a vibration reducing link for vibrating screed; 
         FIG. 3  is a cross-sectional view of the vibration reducing link of  FIG. 2 ; 
         FIG. 4  is a longitudinal sectional view of the invention in  FIG. 1  wherein the section plane is indicated by the arrows A-A of  FIG. 3 ; 
         FIG. 5  is a perspective view of a handlebar element for vibrating screed; 
         FIG. 6  is a perspective view of a handlebar assembly for vibrating screed demonstrating the relative rotational and longitudinal motions of handlebar elements. 
     
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The present invention is illustrated in further detail by the following non-limiting example.  FIG. 1  illustrates a vibration reducing link assembly for a vibrating screed handlebar means  10  comprising a first element  12 , a second element  13  and a third element  14 , the second element  13  and third element  14  capable of relative rotatable displacement and capable of being secured in a desired relative position by clamping means  11 . A vibration reducing assembly  15  (See  FIG. 2 ) according to a preferred embodiment of the present invention dampens vibrations which propagate between coupled second element  13  and third elements  14 . 
     Referring to  FIG. 2 , the vibration reducing assembly  15  is comprised of a vulcanized rubber tubular coupling  16  linking a handlebar element  17  of second element  13  to a tubular element  18 . Vibrations emanating from handlebar element  17  are reduced as they propagate outwardly through the vulcanized rubber tubular coupling  16  to tubular element  18 . 
     Now referring to  FIG. 3 , the vibration reducing assembly  15 , having a vulcanized rubber tubular coupling  16  enclosed by a tubular element  18  and used to link the second element  13  to the third element  14 , is readily visible. As is apparent from this figure, tubular element  18  is isolated from vibrations propagating from handlebar element  17  by a vulcanized rubber tubular coupling  16 . 
       FIG. 4  is a longitudinal sectional view of the invention in  FIG. 1  wherein the section plane is indicated by the arrows A-A of  FIG. 3 . From this figure, the configuration of the vibration reducing link is apparent. Vibrations propagating from handlebar element  17  to tubular element  18  are reduced by a vulcanized tubular coupling  16 . 
       FIG. 5  is a perspective view of the third element  14  of a vibration reducing link assembly for vibrating screed handlebar means  10 . Second element  13  and third element  14  are linked together by inserting the vibration reducing assembly  15  into space  19  of third element  14  and compressing them together by clamping means  11 . 
       FIG. 6  is a perspective view of third element  14  of a vibration reducing link assembly for vibrating screed handlebar means  10  capable of relative rotatable displacement and capable of being secured in a desired relative position to second element  13 . The vibration reducing assembly  15  engages space  19  (See  FIG. 5 ) along the longitudinal axis  21 . Once engaged, third element  14  is rotatably displaceable about the rotational axis  20  and secured to vibration reducing assembly  15  in space  19  by clamping means  11 . 
     In a preferred embodiment of the preferred invention, the use a vibration reducing link as part of screed&#39;s handle assembly has demonstrated a substantial reduction in the remaining vibrations transmitted to the upper sections of the handle assembly. The reduction in vibration is as much as 80% when compared to vibration experience in the handle assemblies of the prior art which do not have additional vibration isolators. 
     Although the present invention has been described hereinabove by way of specific embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention. For example, such a vibration reducing link described herein could be used whenever vibration dampening is needed for other construction equipment such as power trowels, concrete saws, and hand held or walk behind dirt and asphalt compactors utilizing handlebar assemblies. Furthermore, applications for such a vibration reducing grip may also include any situation where a vibrating handlebar needs to be grasped by a user such as is the case, for instance, for power tools, motorcycles, bicycles, and lawnmowers.