Abstract:
A ramming device for compacting soil includes an upper mass and a lower mass. The lower mass is driven linearly back and forth with respect to the upper mass to compact material therebelow. An engine drives the lower mass and is supported by the upper mass. A muffler is fluidly connected to the engine and is contoured such that a majority of the muffler is positioned inboard of a footprint of a side of the ramming device. Preferably, the muffler has a shape that substantially matches a shape of the upper mass adjacent to the muffler thereby further reducing the distance that the muffler extends beyond a footprint of a sidewall of the device.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to grade compacting devices and, more particularly, to a rammer-type compactor having an exhaust system constructed to be positioned snuggly near the body of the compactor. 
     2. Description of the Related Art 
     Compaction is generally performed in preparation of other building processes. Commonly, freshly excavated work sights require compaction of the underlying material, be it soil or gravel, prior to the placement of building materials, such as concrete, over the soil. This compaction can be performed by any of a number of devices including rollers, plate compactors, or rammers. Rammers are a class of compaction device in which an operator can hand-guide a vertically-reciprocating plate or “shoe” over the area to be compacted. The shoe is located on a lower mass driven to reciprocate via a gear crank. The operator&#39;s handle is located on an upper mass that is vibrationally isolated from the lower mass and that supports an engine that powers the gear crank. The compact, relatively light nature of rammers, permit them to be guided even if the grade is at a substantial incline or decline. Rammers are also commonly used in trenches or the like due to their compact and generally elongated vertical shape as well as the ease of mobility of such devices in confined spaces. An operator standing in a trench can relatively easily redirect the direction of travel of the rammer with generally minimal interference from the walls of the trench. 
     A substantial consideration of rammer construction is protection of some of the comparatively fragile components of the rammer assembly from impacts. Commonly, such impacts cause damage due to contact with, debris which may fall from above, or adjacent building materials or structures such as exposed reinforcing rods, etc. Although some such damage may be considered generally cosmetic in nature, such as blemishes to the finish of the machine, other components of the rammer, notably the exhaust system, may be damaged during use. 
     Rammers are also susceptible to damage during transit. The generally upright orientation of rammers complicates the transportation of such devices. When it is impractical to transport the rammer in its normal, upright position, many users lay the rammer on its side so as to avoid undesired tipping of the rammer. Placement of the rammer in such a horizontal orientation presents an additional opportunity for damage to the comparatively fragile or deformable components of the rammer assembly. 
     Others have recognized the importance of protecting the lateral surfaces of rammers from damage. Unfortunately, these solutions are not without their respective drawbacks. One such device includes the positioning of multiple guards around the exhaust system and other relatively fragile components of the rammer. The guards are secured to the comparatively robust components of the engine housing and the gear case. Unfortunately, such a configuration communicates the impact loading of the guards directly to components which, if damaged, render the rammer inoperable. That is, an impact that previously would have resulted merely in “cosmetic” damage now has the potential to render the machine unusable due to fractures of either of the engine block or the crankcase. 
     Such guard systems also undesirably increase the volume occupied by the machine. That is, they increase the space occupied by the machine in storage, during transit, and in use. The guards also increase the weight of the machine, add to manufacturing costs, and complicate maintenance procedures. To mitigate the detrimental weight considerations, some manufactures have formed the guards out of thick-walled aluminum which in turn detrimentally increases the material costs associated with manufacturing the rammer. The guards also must be removed to replace or maintain the components protected by them. Complex fastener assemblies that secure the guards to the machine only further frustrate service efforts. 
     Guard systems assemblies also commonly include a number of openings to allow adequate airflow into the cavity behind the guard. The air flow is necessary for cooling of machine components and combustion. Unfortunately, the number and size of the openings has the tendency of allowing debris to pass through the guards. The holes also provide the potential for poking damage to the components positioned behind the guard. Roots or other structures may also snag on the holes. 
     Therefore, there is a need for a rammer that is constructed to protect the deformable systems of the rammer with consideration given to the weight of the machine and the spatial occupation of the machine. 
     SUMMARY OF THE INVENTION 
     The present invention provides a rammer compactor that overcomes one or more of the above-mentioned drawbacks. A rammer according to one aspect of the invention includes an exhaust system that is maintained in close association with the body of the rammer and shaped such that at least a majority of the exhaust system is positioned inboard with respect to a line that extends between adjacent portions of the body of the rammer, i.e., the “footprint” of those adjacent structures. 
     Another aspect of the invention includes a rammer having an upper mass and a lower mass. The upper mass supports the engine and a crankcase that houses a gear train driven by the engine. The lower mass includes a shoe that is reciprocatingly driven by the gear train to engage the material to be compacted. The rammer additionally includes an exhaust for discharging the gases associated with engine combustion. The exhaust is shaped to fit snuggly within a void formed between the engine and the gear case such that the exhaust is protected from damage simply via its shape. 
     Another aspect of the invention is to provide a rammer that meets the first principal aspect without interfering with the space required for efficient operation of the rammer compactor. 
     Yet another aspect of the invention is to provide a hand guided rammer that meets the first aspect and that does not otherwise hinder access to the serviceable components of the rammer. 
     These and other aspects, advantages, and features of the invention will become apparent to those skilled in the art from the detailed description and the accompanying drawings. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof. It is hereby disclosed that the invention include all such modifications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
         FIG. 1  is a left-side elevational view of a soil compaction device commonly referred to as a rammer and constructed according to the present invention; 
         FIG. 2  is a rear elevational view of the rammer shown in  FIG. 1 ; 
         FIG. 3  is rear-right perspective view of the rammer shown in  FIG. 2  and shows the exhaust wrapping about the rammer; 
         FIG. 4  is a side elevational view of the exhaust shown in  FIG. 3  removed from the rammer; 
         FIG. 5  is a left-rear perspective view of the muffler shown in  FIG. 4 ; 
         FIG. 6  is a right-front perspective view of the muffler shown in  FIG. 5 ; 
         FIG. 7  is a cross-sectional view of the muffler taken along line  7 - 7  shown in  FIG. 4 ; and 
         FIG. 8  is a partial cross-sectional view of the rammer shown in  FIG. 2  taken along line  8 - 8  proximate the muffler. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a hand guided compaction device or rammer  10  according to the present invention. Referring to  FIGS. 1-3 , rammer  10  includes an upper mass  12  and a lower mass  14 . Upper mass  12  includes an engine  16  connected to a crankcase  18  and lower mass  14  includes a compaction plate or shoe  20  and a spring body  22 . Lower mass  14  includes a bellows  24  that extends between a lower spring mount  26  and an upper spring mount  28 . Upper spring mount  28  secures lower mass  14  to upper mass  12 . Spring body  22  includes one or more springs that reciprocate in bellows  24  during operation of the gear train positioned in crankcase  18 . 
     Shoe  20  includes a work face  30  that is configured to engage a work material passed thereunder. Preferably, shoe  20  is replaceable and/or interchangeable such that different compaction performances can be achieved. A lower handle  32  is connected to rammer  10  proximate shoe  20  and is helpful in assisting with non-operating transportation of rammer  10 . The lower handle  32  is typically used only for transporting the rammer  10 . 
     Upper mass  12  includes a recoil starter  34  that is operationally connected to engine  16 . Recoil starter  34  includes a handle  38  connected to a pull rope  36  that facilitates manual starting of engine  16 . Alternatively, rammer  10  may be equipped within an electric start feature. Upper mass  12  additionally includes a fuel tank  40  and an oil tank  42  which provide a combustion charge to engine  16  via a delivery system  44 . Delivery system  44  could be provided as either a carburetor or a fuel injection system. Although engine  16  is shown as what is commonly understood as a two-cycle engine, as evidenced by the separate oil and fuel reservoirs, it is appreciated that engine  16  could be provided as a four-cycle engine. Understandably, such a configuration would commonly include an oil reservoir internal to the engine which would replace oil tank  42 . 
     Regardless of the specific construction of engine  16 , as shown in  FIG. 3 , a number of fasteners  45  secure a frame member  46  to upper mass  12 . Fasteners  45  pass through a flange  48  of frame member  46  and engage crankcase  18 . Alternatively, frame member  46  could be constructed to be supported by the block of engine  16 . Optionally, a number of bushings, or other shock or vibration dampening structures, may be disposed between flange  48  and crankcase  18  to isolate frame member  46  from vibration of rammer  10 . 
     Frame member  46  includes a handle portion  50  that extends outward from a rearward portion of rammer  10 . As used herein, reference to forward or rearward portions of rammer  10  are made with respect to a direction of travel during normal generally vertical operation of rammer  10 . A user interfacing with handle portion  50  during operation of rammer  10  is generally positioned rearward of the machine with respect to a normal forward direction of travel of rammer  10 . Similarly, the right and left sides of rammer  10  are referred to with respect to a user&#39;s left hand and right hand sides when positioned rearward of handle portion  50 . In accordance with this orientation, an operator positioned at handle portion  50  can conveniently manipulate a throttle lever  52  that is positioned proximate the user&#39;s left hand while maintaining control of rammer  10  with his or her right hand. Furthermore, such an orientation positions the operator generally in line with the direction of travel of rammer  10  such that the rammer can be operated in relatively narrow work spaces. 
     Preferably, engine  16  and a gear train (not shown) in crankcase  18  are coupled via a centrifugal clutch such that engine  16  will idle without the gear train generating a drive output. Increasing the operating speed of engine  16  through the manipulation of throttle lever  52  couples the drive shaft of engine  16  to the gear train, thereby generating movement of a rammer piston assembly that moves axially within lower mass  14 . Movement of the rammer piston assembly drives the shoe  20  up and down, thereby compacting the ground passing under shoe  20  in a ramming type manner. 
     Referring to  FIGS. 1 and 2 , a number of reference lines  54 ,  55 ,  56 ,  57  are shown which indicate the outermost “footprint” of respective vertical sides of rammer  10 . As shown in  FIG. 1 , if rammer  10  is positioned on its forward side, indicated by line  54 , rammer  10  is supported by frame member  46  and shoe  20 . Similarly, if rammer  10  is laid on its rearward side, as indicated by line  55 , rammer  10  is also supported by frame member  46  and shoe  20 . Similarly, as shown in  FIG. 2 , rammer  10  is also supported by frame member  46  and shoe  20  if rammer  10  is laid on either of its left or right hand sides, as indicated by lines  56  and  57 , respectively. Understandably, perfectly planar support surfaces are often unavailable. Accordingly, although supporting rammer  10  by one of shoe  20  and a combination of shoe  20  and frame member  46  is desired, less desirable positioning often occurs. Accordingly, rammer  10  is constructed to withstand periodic impacts at points between frame member  46  and shoe  20 , at least with respect to the exhaust side of rammer  10 . 
     As shown in  FIGS. 2-7 , an exhaust  60  that, in this case, comprises a muffler, is mounted on the rear surface of the rammer  10 . Muffler  60  is one of the components of rammer  10  that is desired to be protected from inadvertent impacts. Impacts to muffler  60  can result in damage to the muffler and/or detrimentally affect operation of engine  16  via undesirable exhaust back-pressures. Pursuant to the invention, the muffler is sized and shaped so that at least the majority of it fits within the “footprint” described above. More specifically, muffler  60  includes a body  61  having an inlet end  62  with a flange  64  position thereabout. A number of fasteners  66  secure flange  64  to an exhaust port  68  of engine  16 . Body  61  of muffler  60  includes a first portion  72  and a second portion  74 . First and second portions  72 ,  74  of muffler  60  are oriented in generally crossing directions relative to one another thereby providing for relatively compact spacing of muffler  60  relative to rammer  10 . Hence, first portion  72  of muffler  60  is oriented in a generally vertical orientation and extends in a generally downward direction from exhaust port  68 . Second portion  74  of muffler  60  is oriented in a generally horizontal orientation and extends generally under engine  16  toward the left hand side of rammer  10 . 
     As best shown in  FIGS. 4 and 5 , muffler  60  includes an exhaust opening  76  having a flange or flap  78  positioned thereabout. Exhaust opening  76  has a generally elongated slot-shape and allows for the expulsion of exhaust gases, indicated by arrow  80  proximate exhaust opening  76  in  FIG. 5 , from muffler  60 . Flap  78  reduces the potential of foreign particles entering muffler  60  and directs the exhaust gases away from engine  16  and the operator. 
     Referring to  FIGS. 5-7 , a mounting flange  82  extends from an inboard side  84  of body  61  of muffler  60  whereas a shroud  86  extends from an outboard side  87 . (As used herein, inboard refers to that portion of muffler  60  that generally faces adjacent structure of rammer  10  whereas outboard refers to that portion of muffler  60  that faces toward the operating environment.) Shroud  86 , preferably formed from a light-weight resilient material, such as plastic or a generally thin metal material, is offset from body  61  of muffler  60  such that a space or gap  88  is formed between shroud  86  and body  61  of muffler  60 . As shown in  FIG. 7 , gap  88  provides a degree of thermal isolation between body  61  of muffler  60  and shroud  86 , thereby reducing the potential of an operator being burned by a hot exhaust. Gap  88  also allows for deformation of shroud  86  toward body  61  of muffler  60  such that, in the event a foreign object or particle would impact muffler  60 , shroud  86  absorbs some or all of the energy associated with the impact. As shown in  FIG. 5 , shroud  86  includes a number of openings or passages  90  that are oriented to cooperate with mounting structures of muffler  60 . That is, passages  90  are sized, shaped, and positioned to allow uninterrupted passage of common tools beyond shroud  86  for servicing and/or mounting muffler  60  to rammer  10 . 
     Referring to  FIGS. 4-7 , mounting flange  82  includes a number of fastener holes  94  that are aligned with corresponding holes formed in the block of rammer engine  16  when muffler  60  is secured thereto. Understandably, holes  94  could also be configured to correspond with holes formed in crankcase  18  or a combination of holes formed in each of block of engine  16  and crankcase  18 . Mounting flange  82  is also vertically offset from body  61  of muffler  60  such that the flange  82  abuts rammer  10  when inlet flange  64  is secured to the exhaust port  68  of engine  16 . Such a construction allows muffler  60  to be quickly aligned with and secured to the mating structures of rammer  10 . Furthermore, slightly offsetting muffler  60  from the remainder of rammer  10  provides an additional impact absorbing feature in that any impact loading of muffler  60  is communicated to the respective connection points. Alternatively, where an even more compact absorption capability is desired, it is appreciated that mounting flange  82  could extend from body  61  of muffler  60  such that body  61  is maintained in very near direct contact with engine  16  or crankcase  18 . 
     Referring now to  FIG. 7 , exhaust gas  80  enters muffler  60  at inlet end  62 , traverses the passages associated with first portion  72  and second portion  74 , and is expelled from muffler  60  at exhaust opening  76 . Flap  78  directs exhaust gas  80  is a direction downward and away from an operator. Optionally, an exhaust gas passage  98 , or that volume defined by body  61  between inlet end  62  and exhaust opening  76 , is wholly or partially traversed by an optional catalyst  100 . Optional catalyst  100  converts one or more of the less desirable constituents of the exhaust gas mixture to a less environmentally detrimental composition. It is further appreciated that optional catalyst  100  could be configured to be replaceable or sized to be operable for a designed operating life of rammer  10 . 
     Referring to  FIG. 8 , engine  16  and crankcase  18  each have an exterior surface  102 ,  104 , respectively. Engine  16  and crankcase  18  are constructed such that, when connected, a void or cavity  106  is formed proximate the interface of engine  16  and crankcase  18 . Muffler  60  is constructed to be snuggly received within cavity  106  such that at least a substantial portion  108  of muffler  60  is positioned inboard of a line  110  that is tangent to both the exterior surface  102  of engine  16  and the exterior surface  104  of crankcase  18 . Preferably, muffler  60  is constructed such that at least a majority of the cross-section of the vertical first portion  72  of muffler  60  is positioned in cavity  106 . Referring to  FIGS. 2 and 8 , in the event an obstruction passes inboard of line  57  shown in  FIG. 2 , exhaust gas passage  98  of muffler  60  is protected from collapse by both shroud  86  and the snug positioning of muffler  60  inboard of the adjacent contours of engine  16  and crankcase  18 . 
     Hence, rammer  10  is constructed with multiple features for protecting the operational integrity of the muffler  60 . Furthermore, these protection protocols do not overly complicate the serviceability of the rammer. Therefore, the inventive system reduces the potential of inadvertent damage to the deformable components of the rammer without unduly complicating servicing and/or maintenance of such components. 
     It is appreciated that many changes and modifications could be made to the invention without departing from the spirit thereof. Some of these changes, such as its applicability to rammers having two or four cycle engines, are discussed above. Other changes will become apparent from the appended claims. It is intended that all such changes and/or modifications be incorporated in the appending claims.