Abstract:
This invention relates generally to an impact tool. The present invention provides a vibration isolated impact tool wherein an impact mechanism and a motor assembly are arranged into a cartridge assembly. An elastomeric member resiliently connects the cartridge assembly with a housing. The cartridge assembly is free to move axially and rotationally within the housing. The elastomeric member absorbs axial vibration and torsional vibration, reducing the vibration transmitted to an operator.

Description:
This application is a divisional of Ser. No. 09/410,915, filed on Oct. 1, 1999, pending. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to impact tools and, more particularly, to an impact wrench including vibration isolation. 
     BACKGROUND OF THE INVENTION 
     Impact tools such as impact wrenches are well known in the art. Generally, the impact tools include an air motor and a clutch mechanism. Typically, the impact tool transmits shock and vibration from the tool head to the handle. In turn, the shock and vibration is transmitted from the handle to an operator holding the handle. 
     SUMMARY OF THE INVENTION 
     The present invention provides a vibration isolated impact tool wherein an impact mechanism and a motor assembly are arranged into a cartridge assembly. An elastomeric member resiliently connects the cartridge assembly with a housing. The cartridge assembly is free to move axially and rotationally within the housing. The elastomeric member absorbs axial vibration and torsional vibration, reducing the vibration transmitted to an operator. 
     The present invention generally provides an apparatus comprising: a housing; an impact mechanism generating an axial force and a torsional force; a motor for rotating the impact mechanism; and an elastomeric member connecting the impact mechanism and the motor with the housing, and wherein the elastomeric member is attached such that the elastomeric member absorbs both axial and torsional forces. This aspect provides for a vibration isolated impact tool that reduces the axial and torsional forces received by the user of the tool. 
     The second aspect in accordance with the present invention provides a method comprising the steps of: providing a housing; providing a cartridge assembly including a motor and an impact mechanism; slidably receiving the cartridge assembly into the housing; and providing an elastomeric member connecting the cartridge assembly with the housing, wherein the elastomeric member absorbs axial and torsional vibrational forces. The second aspect provides similar advantages to those of the first aspect. 
     The third aspect in accordance with the present invention provides a cartridge, slidably received within a housing of an impact tool, comprising: a motor, having a first end adapted to be coupled to an elastomeric member; an impact mechanism, generating an axial force and a torsional force, having a first end operatively coupled to a second end of the motor; and an anvil operatively coupled to a second end of the impact mechanism. This aspect provides similar advantages to those of the first aspect. 
     The fourth aspect in accordance with the present invention provides an elastomeric member, resiliently mounted within a housing of an impact tool, comprising a first surface adapted to be coupled to a motor, a second surface adapted to be coupled to the housing of the impact tool, and means for attachment for allowing the elastomeric member absorb axial and torsional forces created within the impact tool. This aspect provides similar advantages as those in the first aspect. 
     The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the present invention will best be understood from a detailed description of the invention and a preferred embodiment thereof selected for the purposes of illustration and shown in the accompanying drawings in which: 
     FIG. 1 illustrates a cross-sectional view of an impact tool, in accordance with a preferred embodiment of the present invention; 
     FIG. 2 illustrates a cross-sectional view of a cartridge assembly; 
     FIG. 3 illustrates a cross-sectional view of an elastomeric member; 
     FIG. 4 illustrates a front view of the elastomeric member; and 
     FIG. 5 illustrates a cross-sectional view of an impact mechanism. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although certain preferred embodiments of the present invention will be shown and described in detail, it should be understood that various changes and modifications may be made without departing from the scope of the appended claims. The scope of the present invention will in no way be limited to the number of constituting components, the materials thereof, the shapes thereof, the relative arrangement thereof, etc., and are disclosed simply as an example of the preferred embodiment. The features and advantages of the present invention are illustrated in detail in the accompanying drawings, wherein like reference numerals refer to like elements throughout the drawings. Although the drawings are intended to illustrate the present invention, the drawings are not necessarily drawn to scale. 
     Referring to FIG. 1, there is a cross-sectional view of a tool  10  depicted, including generally, a handle  12  fixedly mounted to a housing  14 . A cartridge assembly  16  is slidably received within housing  14 . An elastomeric member  18  is resiliently mounted within the rear of housing  14 . 
     FIG. 2 illustrates a cross-sectional view of cartridge assembly  16 , which includes an impact mechanism or generator  20  and a motor assembly  22 . Impact generator  20 , contained within an impact generator housing  24 , includes a clutch mechanism  26 , (FIGS.  2  and  5 ), a timing shaft  28 , a dog hammer  30  and a power output shaft or anvil  32 . Anvil  32  includes at least two rearwardly projecting lobes  36  which receive the axial impact transmitted from dog hammer  30 . Rotational energy is transmitted from an output shaft  34  to dog hammer  30 , which impacts anvil  32 . The anvil  32  is depicted as a spline, but may be various shapes, such as hex or square. 
     Timing shaft  28  includes a ball engaging track  38 . Similarly, dog hammer  30  includes a ball engaging track  40 . A ball  42  follows ball engaging tracks  38  and  40  of timing shaft  28  and dog hammer  30 , respectively. Timing of the impacts is determined by the relationship of ball engaging tracks  38  and  40 . Dog hammer  30  moves in an axial direction to strike lobes  36  of anvil  32 , which is subsequently returned to a non-impact position relative to dog hammer  30  by a spring  44 . Axial and torsional forces generated by clutch mechanism  26  are transmitted through anvil  32 . 
     FIG. 2 also depicts motor assembly  22  including output shaft  34  which supplies the rotational motion to clutch mechanism  26 . Motor assembly  22  is air powered, but can be powered by any other suitable means, such as, electric, hydraulic, gas, etc. Air is provided to motor assembly  22  via an air inlet port  48 . 
     FIG. 3 depicts a cross-sectional view of elastomeric member  18 , while FIG. 4 depicts a front view of elastomeric member  18 . Referring also to FIG. 1, a first side  56  of elastomeric member  18  is attached to a rear attachment plate  58  of motor assembly  22  using a plurality of fasteners  60  (two are shown as  60 A,  60 B). A plate  62  is located between fasteners  60 A,  60 B and a second side  64  of elastomeric member  18 . A raised portion  66  of second side  64  of elastomeric member  18  is received in a recessed portion  68  of the rear cover  15  of housing  14 . Raised portion  66  of elastomeric member  18  is held within recessed portion  68  of rear cover  15  by a stop  76 . The raised portion  66  increases the surface area and thus the frictional force for prevent slippage of the elastomeric member. Elastomeric member  18  absorbs both axial and torsional vibration generated by cartridge assembly  24 . This reduces the vibration transmitted through housing  14  to handle  12 , and ultimately to the operator. An advantage of elastomeric member  18  is the ease of replacement by removal of rear cover  15 , and fastens  50 A,  60 B. 
     Elastomeric member  18  is preferably made of neoprene rubber for durability, but may be made from any suitable dampening material, such as, polyurethane, rubber, neoprene rubber, etc. It should be noted that the shape and size of elastomeric member  18  may be varied to alter the torsional versus axial rigidity of elastomeric member  18  as needed for particular applications. Therefore, the size and shape of elastomeric member  18  are not limited by the preferred embodiment. For instance, elastomeric member  18  does not have to have raised portion  66 . Likewise, the fastening means by which elastomeric member  18  is secured within rear attachment plate  58  is not limited by the preferred embodiment. For instantce, elastomeric member  18  may be fastened to rear attachment plate  58  via glue, etc., not requiring stop  76 . 
     As in FIG. 1, cartridge assembly  16  is free to move both axially and rotationally within housing  14 . A stop  50 , also depicted in FIG. 1, prevents cartridge assembly  16  from sliding through the front opening  52  of housing  14 . A plurality of seals  54 A,  54 B, and  54 C prevent air from leaking beyond motor assembly  22 . 
     It should also be noted that the present invention was described utilizing a clutch mechanism  26 , but it is not limited to the use of a clutch. 
     The foregoing description of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in light of the above teaching. Such modifications and variations, that may be apparent to a person skilled in the art, are intended to be included within the scope of this invention as defined by the accompanying claims.