Abstract:
An environmental shield for reducing or eliminating leakage of materials from transit vehicles, including truck-mounted concrete mixers, is provided. The environmental shield preferably engages at least a portion of an opening on a mixer drum such that the leakage that generally occurs in such situations as travel along hilly or bumpy terrain, surging, etc. may be prevented or minimized. The environmental shield preferably includes a discharge cover and a combination steel/rubber abrasion resistant sealing member and may be preferably coupled to a charging hopper of the transit vehicle.

Description:
TECHNICAL FIELD OF THE INVENTION 
   The present invention relates generally to preventing the leakage of wet concrete from a concrete mixer and, more particularly, to an environmental shield for preventing leakage from a truck-mounted concrete mixer. 
   BACKGROUND OF THE INVENTION 
   In part to enable transit concrete mixers to transport greater payloads, a reduction in weight of the concrete mixers has been commonly pursued. One technique to reduce the weight of truck mounted concrete mixers has been to eliminate a rear, closing door previously associated with such mixers. The elimination of the rear, closing door has given rise to the problem of leakage or spillage of wet concrete through the open end of the mixer drum. Such spillage or leakage may result from increased loads, transport across hilly terrain as well as surging of loads during transit. 
   While some efforts have been made to address the problem of leakage or spillage, they have generally been less than satisfactory. For example, the configuration of mixing blades within a mixer have some effect on maintaining wet concrete within the mixer. However, the mixing blades generally have an effect on minimizing leakage only when the mixer is rotated in the mixing direction. Other methods to address the problem of leakage have been directed principally towards returning any leakage or spillage to the mixer as opposed to preventing or reducing the leakage. 
   SUMMARY OF THE INVENTION 
   In accordance with teachings of the present disclosure, a system and apparatus are described for reducing or eliminating the leakage of wet concrete from truck-mounted concrete mixers. In one aspect of the present invention, a charging hopper for use in charging a rotatable mixer is provided. The rotatable mixer preferably includes a drum having a drum opening at one end for receiving and discharging contents. The charging hopper preferably includes a chute having a charging opening and a discharge opening at respective ends thereof. The charging hopper is preferably operable to couple to the drum such that the discharge opening is disposed proximate the drum opening. The charging hopper preferably further includes a discharge cover operably coupled to the chute proximate the discharge opening. At least one flexible sealing member having respective first and second faces may be disposed on the discharge cover such that the flexible sealing member engages at least a lower portion of the drum opening when the rotatable mixer is being charged. 
   In another aspect, a mixer having a rotatable drum maintained in a frame is provided. The rotatable drum preferably includes a drum opening at one end of the drum operable to receive contents to be agitated and further operable to discharge agitated contents from the drum. A motor preferably coupled to the drum and operable to rotate the drum in the frame is also preferably included on the mixer. The mixer preferably further includes a charging hopper having a chute, a charging opening and a discharge opening disposed proximate the drum opening. The charging hopper preferably further includes an environmental shield disposed proximate the discharge opening of the charging hopper. The environmental shield generally includes a discharge cover having respective first and second faces, a first edge and a generally curved second edge operably coupled to the chute along the first edge. The environmental shield generally includes a discharge cover having respective first and second faces, a first edge and a generally curved second edge operably coupled to the chute along the first edge. The environmental shield preferably further includes a generally cupped sealing member disposed on the second generally curved edge of the discharge cover. The generally cupped sealing member is preferably operable to engage the drum opening such that leakage of contents therefrom may be reduced. 
   In yet another aspect, a concrete mixer truck having a rotatable mixer mounted thereon is provided. The rotatable mixer preferably includes a drum with a drum opening at one end for receiving contents into and discharging contents from the drum. The mixer preferably farther includes a charging hopper having a discharge opening proximate a first end of a chute and a charging opening proximate a second end of the chute disposed proximate the drum opening. An environmental shield operably disposed proximate the discharge opening of the charging hopper is also preferably included on the concrete mixer truck. The environmental shield preferably includes a discharge cover and at least one sealing member operably coupled thereto. The sealing member is preferably operable to engage at least a lower portion of the drum opening such that leakage of contents therefrom may be reduced. 
   The present invention provides the advantage of reducing or eliminating material blow-back during the charging cycle of a mixer. 
   The present invention also provides the technical advantage of a reduction or elimination of dust emissions from a mixer. Such a reduction in dust emissions may result in a reduced environmental impact as well as in reduced maintenance of the mixer. 
   Additional technical advantages provided by the present invention include safety and clean-up benefits that may result from a reduction or elimination of leakage or spillage from a mixer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
       FIG. 1  is a view in elevation illustrating a concrete mixer truck having a truck-mounted mixer incorporating teachings of the present invention; 
       FIG. 2A  is a schematic drawing in elevation with portions cut away of the rear portion of the concrete mixer truck of  FIG. 1  illustrating a charging hopper and environmental shield assembly incorporating teachings of the present invention; 
       FIG. 2B  is a schematic drawing in elevation with portions cut away showing a side view of the charging hopper and environmental shield assembly of  FIG. 2A ; 
       FIG. 3A  is a schematic drawing illustrating one embodiment of a discharge cover incorporating teachings of the present invention; 
       FIG. 3B  is a view in elevation with portions cut away of a discharge lip weldment that may be included on the discharge cover of  FIG. 3A ; 
       FIG. 4A  is a plan view illustrating one embodiment of a shield finger incorporating teachings on the present invention; 
       FIG. 4B  is a schematic drawing in elevation with portions cut away showing a side view of the shield finger of  FIG. 4A ; 
       FIG. 5A  is an illustration of a side plan view of a gusset. 
       FIG. 5B  is an illustration of an edge view of the gusset illustrated in  FIG. 5A . 
       FIG. 6  is a plan view illustrating a sealing member incorporating teachings of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Preferred embodiments of the invention and their advantages are best understood by reference to  FIGS. 1 through 6 , wherein like numbers are used to indicate like and corresponding parts.  FIG. 1  is a schematic drawing elevation illustrating a concrete mixing truck having a truck-mounted mixer incorporating teachings of the present invention. 
   Preferably included on transit mixer or concrete mixer truck  100  is mixer  103 . Mixer  103  is preferably maintained in a frame that may include mounts  104  and  105 . Mixer  103  preferably includes motor  106  operable to rotate drum  109 , discharge chute  112  operable to direct contents discharged from drum  109 , and charging hopper  115  operable to aid in charging drum  109  with contents, among other components. 
   Charging hopper  115  is preferably operable to be repositioned. As such, charging hopper  115  may be pivoted or displaced about a pivot point on bracket  118  to allow such repositioning. Other methods and apparatuses for repositioning charging hopper  115  are considered within the scope of the present invention. 
   One position which charging hopper  115  may assume is a first or charging position. In its first or charging position, illustrated in  FIG. 1 , charging hopper  115  preferably allows wet concrete, the materials, cement, water and gravel, to make concrete, and/or other materials to be placed into drum  109  through a drum opening preferably included thereon. During charging of drum  109 , i.e., when charging hopper  115  is in its first, charging position, an environmental shield preferably disposed thereon may be employed to reduce the amount of leakage or spillage commonly experienced during drum  109  charging operations. 
   During travel of truck  100 , such as after charging drum  109 , in route to a job site, charging hopper  115  may be maintained in the first or charging position illustrated in  FIG. 1 . Maintaining charging hopper  115  in its first or charging position preferably maintains the environmental shield  203  coupled thereto in generally sealably engagement with drum opening  233  (see  FIG. 2A ) preferably included on drum  109 . As a result and in such instances as the surging of contents contained in drum  109  or the travel of concrete mixer truck  100  over sloped or hilly terrain, maintaining charging hopper  115  in its first position enables environmental shield  203  of the present invention to prevent or reduce leakage of contents from drum  109 . 
   During the discharge of contents from drum  109 , such as at a job site, charging hopper  115  is preferably displaced from the rear opening  233  (see  FIG. 2A ) of drum  109 . Such a displacement of charging hopper  115  generally involves pivoting charging hopper  115  about bracket  118  such that charging hopper  115  may come to rest in its second position above or aside drum  109  and clear of the drum opening  233  (see  FIG. 2A ) preferably included thereon. In addition, such displacement of charging hopper  115  preferably alleviates the engagement between the environmental shield  203  and the discharge or drum opening  233  (see  FIG. 2A ) of drum  109 . 
   In  FIG. 2A , a plan view with portions cut away depicting the rear portion of concrete mixer truck  100  illustrating a charging hopper  115  and environmental shield  203  combination incorporating teachings of the present invention is shown. Environmental shield  203  may be preferably coupled to charging hopper  115  along a first edge as illustrated in  FIG. 2A  or by using alternative attachment methods. 
   Charging hopper  115  preferably includes charging opening  121 , chute  124  and discharge opening  127 . Charging hopper  115  may be employed in the filling or charging of drum  109 . Other embodiments of charging hopper  115  are considered within the scope of the present invention. During charging, charging hopper  115  is generally disposed proximately drum opening  233 . Charging opening  121  is preferably positioned near the top of drum  109  such that contents may be inserted therein. Discharge opening  127  is generally positioned proximate to drum opening  233  such that contents placed in charging opening  121  may travel along chute  124  to be released from discharge opening  127  into drum  109 . 
   Environmental shield  203  preferably includes discharge cover  206 , first  209 , second  212  and third  215  gussets, first  218 , second  221  and third  224  flexible sealing members as well as shield fingers  227 . Shield fingers  227  are preferably coupled to discharge cover  206  with studs  230  or other mechanical fasteners. 
   As illustrated in  FIG. 2A , environmental shield  203  preferably sealably engages drum opening  233  of drum  109 . As further illustrated in  FIG. 2A , environmental shield  203  has been designed to cover at least the lower portion of drum opening  233 . However, larger environmental shields may be designed to cover a greater portion of drum opening  233 . 
   Environmental shield  203  is preferably maintained in a generally sealed engagement with drum opening  233  such that leakage of contents from drum opening  233  may be reduced. To accomplish such an engagement, flexible sealing members  218 ,  221  and  224  are preferably held against rim  236  by shield fingers  227 . By using shield fingers  227  that are spring biased, a generally constant force may be applied to flexible sealing members  218 ,  221  and  224  such that they maintain engagement with rim  236  of drum opening  233 . A Drip ring may also be present on mixer  103  proximate drum opening  233 . 
     FIG. 2B  is a schematic drawing showing a side view with portions broken away of drum  109 , charging hopper  115  and environmental shield  203  assembly of  FIG. 2A . As mentioned above, environmental shield  203  preferably sealably engages drum opening  233  when charging hopper  115  is in its first or charging position illustrated in  FIG. 1 . When charging hopper  115  is in its charging position, environmental shield  203  may prevent or reduce leakage or spillage from drum opening  233 , and, as further illustrated in  FIG. 2B , environmental shield  203  may have a generally concave cupped shape. The concave configuration of flexible sealing members  218 ,  221  and  224  results, in part, from shield fingers  227 , and further enables sealing members  218 ,  221  and  224  of environmental shield  203  to sealably engage drum opening  233 . 
   In  FIG. 3A , a plan view illustrating an embodiment of discharge cover  206  for use in environmental shield  203  incorporating teachings of the present invention is shown. Discharge cover  206  may be made from various metals such as steel alloys or any other material having satisfactory characteristics. Discharge cover  206  preferably includes first  303  and second  306  discharge lips disposed thereon. Discharge lips  303  and  306  may be employed to maintain studs  230 . Studs  230  may be employed to couple sealing members  218 ,  221  and  224  as well as shield fingers  227  to discharge cover  206 . As mentioned above, other methods and apparatus for coupling discharge cover  206  to sealing members  218 ,  221  and  224  may be employed. 
   In  FIG. 3B , a view in elevation with portions cut away of discharge lip  306  and discharge cover  206  incorporating teachings of the present invention are shown. Discharge lips  303  and  306  may be disposed on discharge cover  203  as illustrated in  FIG. 3B . Sloping discharge lips  303  and  306  as illustrated, enables sealing members  218 ,  221  and  224  to be influenced to take on the generally concave or cupped shape illustrated in  FIG. 2B  when coupled thereto. 
   In  FIG. 4A , a plan view illustrating one embodiment of a shield finger  227  incorporating teachings on the present invention is shown. Shield fingers  227  preferably include body  403 , first end  406  and second end  409 . Second end  409  preferably includes aperture  412  therein such that shield finger  227  may be attached to stud  230  and/or to discharge lips  303  and  306  and discharge cover  206 . 
   In  FIG. 4B , a view in elevation with portions cut away of shield finger  227  of  FIG. 4A  is shown. As mentioned above, shield finger  227  may be spring biased. One method to achieve such spring biasing of shield fingers  227  is to include bends in shield finger  227  where first end  406  joins body  403  as well as where second end  409  joins body  403 . The generally concave or cupped shape of environmental shield  203  illustrated in  FIG. 2B  is produced, in part, from the pressure applied by the spring biasing preferably included in the design of shield fingers  227  on sealing members  218 ,  221  and  224  as well as from the sloped disposition of discharge lips  303  and  306  illustrated in  FIGS. 3A and 3B  on discharge cover  206 . 
   In  FIGS. 5A and 5B , a plan view illustrating one embodiment of a gusset, such as gusset  209 ,  212  or  215 , for use with environmental shield  203  incorporating teachings of the present invention is shown. Gusset  209 ,  212  or  215  may be formed from various metals such as steel alloys, iron or other suitable material. Gussets  209 ,  212  and  215  preferably include sloped ends  506  and  506 . Sloped ends  503  and  506  enable gussets  209 ,  212  and  215  to be preferably attached to chute  124  of charging hopper  115  and to discharge cover  206  as illustrated in  FIGS. 2A and 2B . Gussets  209 ,  212  and  215  preferably provide structural support to the charging hopper  115  and environmental shield  203  assembly. Other methods of attaching one or more gussets to discharge cover  206  and chute  124  may be employed. 
   Also in  FIGS. 5A and 5B , a view in elevation of a gusset in accordance with teachings of the present invention is shown. Gussets  209 ,  212  and  215  may be formed from metal sheets. Forming gusset  209 ,  212  and  215  as illustrated preferably enables environmental shield  203  to be drum opening  233  when charging hopper  115  is disposed in its first or charging position. The force with which environmental shield  203  is held against rear opening  233  of drum  109  is preferably sufficient to create a generally leak-proof seal between drum opening  233  and sealing members  218 ,  221  and  224  of environmental shield  203  such that the leakage or spillage of materials from within drum  109  may be prevented or reduced. 
   In  FIG. 6 , a plan view illustrating a sealing member incorporating teachings of the present invention is shown. Sealing members  218 ,  221  and  224  may be made from any suitable elastomeric material. Preferably, the material chosen to form sealing members  218 ,  221  and  224  is abrasion resistant and semi-rigid. In one embodiment of the present invention, the sealing member employed on environmental shield  203  may be made from multiple smaller seals. However, other embodiments of forming sealing members  218 ,  221  and  224  are considered within the scope of the present invention. 
   Sealing members  218 ,  221  and  224  preferably include apertures  603  along one edge. Apertures  603  enable sealing members  218 ,  221  and  224  to be operably engaged with discharge lips  303  and  306  preferably using studs  230 . 
   Although the disclosed embodiments have been described in detail, it should be understood that various changes, substitutions and alterations can be made to the embodiments without departing from their spirit and scope.