Patent Publication Number: US-8123592-B2

Title: Heatless slurry system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority on U.S. Provisional Application No. 60/984,867, filed on Nov. 2, 2007 and which is herein incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a heatless slurry system. More specifically, the present invention is concerned with a slurry system for restoring a surface such as glass. 
     BACKGROUND OF THE INVENTION 
     Glass restoration systems are used to remove scratches, mineral deposits or other stains from a valuable piece of glass to save the cost of replacing it. The main components of a known glass restoration system are a pump, a tool for polishing or fining, a water supply tank, hoses, and a slurry container. The container contains the slurry, a mixture of minerals and water forming an abrasive polishing solution. Hoses run from the container to the tool, comprised of a drill to which is attached a polishing or fining pad or disc. Also connected to the hoses, there is a submersible pump placed inside the container for recirculation of the slurry. The slurry goes from the pump through the tool, onto the disc and working surface interface and back into the container before being pumped again. When the pump operates, a vacuum is created between the tool and the working surface. 
     With the above known glass restoration system, the flow of slurry cools the working surface and allows a faster rotation of the tool, resulting in a rapid completion of the work. However, this known glass restoration system causes a considerable heat of the slurry. Indeed, the heat created by the working pump located inside the slurry container is transferred directly to the re-circulated slurry thereby overheating it. When the slurry reaches a certain temperature, chemical reactions with catalysts within the slurry slow down and the slurry thus loses its ability to remove scratches by over 50% and has to be replaced. The work must be interrupted for a considerable period of time since the slurry has to be pre-mixed by hand in the container before starting back the pump. 
     Furthermore, if the slurry is used beyond a certain temperature, the tool shroud melts and the polishing or fining disc or pad becomes warped. Since this known glass restoration system heats the slurry considerably, the user needs to be constantly aware of the slurry temperature to avoid damage to the tool. For example, the user typically needs to stop working to wait for the slurry compound and the tool to cool down, thus leading to wasted time. 
     In order to overcome heat problems associated conventional slurry systems, the prior art teaches the use of systems for cooling the slurry compound as it circulates through the grinding/polishing system. Such a cooling system typically includes a cooling module, such as a refrigeration unit, connected to a heat-transfer device. In operation, the cooling module cools the heat-transfer device, which in turn cools the slurry compound. However, such cooling systems are typically used to overcome heat generated by the various sources within the slurry system and, as such, the pump itself has not been identified as the major source of heat to be overcome. 
     Consequently, there exists a need for a slurry recirculation system linked to the tool, used for polishing or fining or the like, that does not overheat the abrasive polishing solution or slurry and allows continuous use of the polishing tool. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a heatless slurry system for restoring a surface comprising a container containing an abrasive slurry solution; a tool adapted to be moved across the surface for restoration thereof, the tool comprising a housing having mounted thereto a first connection line in fluid communication with the container for drawing the abrasive slurry solution into the housing and a second connection line for removing the drawn abrasive slurry solution from the housing; and a pump comprising an inlet and an outlet connected to the container for providing fluid communication therewith. The outlet comprises a pressurized vessel for creating a vacuum pressure as the abrasive slurry solution is pumped from the container through the inlet and expelled through the outlet. The pressurized vessel is connected to the second connection line. The vacuum pressure draws the abrasive slurry solution into the housing via the first connection line and subsequently removes the drawn abrasive slurry solution from the housing via the second connection line, thereby creating a flow of the abrasive slurry solution within the housing for restoring the surface. A surface of the pump is removed from the abrasive slurry solution for thermally isolating the pump therefrom, thereby preventing a rise in a temperature of the abrasive slurry solution as a result of operation of the pump. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the appended drawings: 
         FIG. 1  is a perspective view of a heatless slurry system in accordance with an illustrative embodiment of the present invention; 
         FIG. 2  is a top perspective view of an opened slurry container of the heatless slurry system of  FIG. 1 ; 
         FIG. 3  is a top perspective view of a slurry container of the heatless slurry system of  FIG. 1 ; 
         FIG. 4  is a sectional, part schematic view of the heatless slurry system of  FIG. 1 ; 
         FIG. 5   a  is a sectional, part schematic view of a heatless slurry circulation system in accordance with an alternative illustrative embodiment of the present invention; 
         FIG. 5   b  is a sectional, part schematic view of a heatless slurry circulation system in accordance with a further alternative illustrative embodiment of the present invention; and 
         FIG. 5   c  is a sectional, part schematic view of a heatless slurry circulation system in accordance with yet a further alternative illustrative embodiment of the present invention. 
     
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The present invention is illustrated in further details by the following non-limiting examples. 
     Referring now to  FIG. 1 , a heatless slurry system, generally referred to using the reference numeral  10 , will now be described. The heatless slurry system  10  includes a slurry container  12  containing an abrasive slurry solution, a polishing tool  24  and a pump  16  illustratively positioned externally with respect to the container  12 . As it will be apparent to those skilled in the art, the polishing tool  24  may be replaced by a fining tool or other similar tools for restoring a surface. A separate water tank  14  may be used as it will be explained further herein below. The pump  16  creates a vacuum effect that eases the displacement of the polishing tool  24  on a surface (e.g. glass  26  or the like, shown in  FIG. 4 ) to be restored while also enabling the abrasive solution to be extracted from the container  12  into the tool  24  for restoring the surface. In particular, scratches, stains, deposits, splatters, spots caused by acid rains, and other alterations (e.g. as much as 0.001 inch deep and about two (2) inches wide) of the surface to be restored may be fixed using the system  10 . The purpose of the water tank  14  is to ease the displacement of the tool on the surface to be restored. Indeed, in use, water is directly brought by a hose  17  from the water tank  14  to the tool  24  and used as a lubrication means between the tool  24  and the surface to restore. 
     Referring now to  FIG. 2  and  FIG. 3 , the slurry container  12  is closed by a lid  18  and illustratively contains slurry supply liquid  20  containing abrasive or rubbing compound particles, solids or the like (not shown), in suspension, which act as catalysts that chemically react with the surface to restore in order to make ease treatment thereof and thus achieve the desired abrasive effect. A vacuum gauge  22  may be mounted to the container lid  18  to serve as an indicator of the good functioning of the pump (reference  16  in  FIG. 1 ) by measuring the vacuum pressure created in the heatless slurry system, as discussed in further detail herein below. A vacuum bleed valve  62  may also be attached to the container lid  18  to adjust the amount of vacuum circulation within the system  10 . 
     Referring now to  FIG. 4 , in operation, the heatless slurry system  10  is used in conjunction with a tool  24 , which can either be arranged for a polishing, fining and/or grinding step (with a grinding tool  24  shown in  FIG. 4  for illustrative purposes) with the arrangements described herein above being the same for tools as in  24  used in both operations. The tool  24  is illustratively supported on the surface of a plane of glass  26 , which for example has a scratch (not shown) to be removed. Such a tool  24  comprises a generally conically-shaped housing or shroud  28  made of semi-flexible plastic, such as ABS plastic. A grinding pad (or fining disc)  30  is mounted within the housing  28  such that a lower edge thereof defines a plane that is substantially flush with the surface of the glass  26  to be repaired, thus ensuring proper operation of the polishing pad  30 . A seal  32  is further provided around the perimeter of the housing  28  to seal the latter against the surface of glass  26  being worked on. A housing tube  34  is also connected to the shroud  28  and supports a drive shaft (not shown) for driving the polishing pad  30 . A motor support plate (not shown) is mounted to the upper end of the housing tube  34  for supporting a high speed electric motor  36  (e.g. 120 volt AC, 6000-7000 rpm) spaced laterally from the housing tube  34 . A retraction lever  38  is pivotally attached to the support plate, such that when the lever  38  is pivoted by causing an arm section (not shown) thereof to move towards the housing tube  34 , the polishing pad  30  is urged downwardly towards the surface of the glass  26  through the use of a spring assembly (not shown). 
     Still referring to  FIG. 4 , in order to carry out the grinding (or alternatively the fining or polishing) operation, the pump  16  illustratively does not itself supply the tool  24  with slurry  20  but rather creates a vacuum effect that promotes slurry circulation. For this purpose, a slurry intake tube  40  is connected to the polishing tool  24  through an adapter (e.g. a rotary fitting)  42  to draw the slurry  20  from the slurry container  12  up to the tool  24  using vacuum pressure created by the pump  16 , as discussed in further detail herein below, and circulate the drawn slurry  44  through the tool  24 . For this purpose, a vacuum and draw tube  46  is mounted through a fitting  48  to a lower portion of the housing  28  adjacent the glass surface  26 . The vacuum and draw tube  46  pulls from the tool  24  part of the slurry  44  previously drawn by the intake tube  40  and used during the grinding (or fining, polishing) operation back into the slurry container  12 . As such, when a lower surface of the housing  28  is placed on the inclined glass  26 , with the level of slurry  44  tilted relative to a longitudinal axis X of the housing  28 , a vacuum is established by action of the pump  16  and a continuous flow of slurry  20  circulates from the slurry container  12  into the housing  28  and back to the slurry container  12 , as further described herein below. Once such a slurry circulation is established, the motor  36  is turned on and the lever  38  actuated to allow the polishing pad  30  to be pulled from or extended onto the glass  26 , with the pad  30  momentarily holding the slurry  44  and forcing the latter against the glass  26  through an aperture (not shown). The tool  24  is then manually moved across the surface of the glass  26  to be repaired (with an axis of rotation X substantially normal to the surface) utilizing the slurry  44  to lap away a fine layer of the glass  26 . Once the grinding (or fining, polishing) action has been completed, the motor  36  can be turned off, resulting in the slurry  44  being fully drained from the housing  12  back into the slurry container  12  and the tool  24  being subsequently lifted away from the surface glass  26  by actuation of the retraction lever  38 . 
     Still referring to  FIG. 4 , in order to create the vacuum effect desired for operation of the tool  24 , an inlet tube  50  and an outlet tube  52  are provided to connect the slurry container  12  to the pump  16 . In particular, vacuum is created by slurry  20  being pumped from the slurry container  12  through tube  50  and expelled by the pump  16  back towards the slurry container  12  through a pressurized vessel, such as a venturi  54  or the like, mounted on the tube  52  well below the level of slurry  20 . As will be apparent to a person skilled in the art, a vessel other than the venturi  54  may be used so long as an outlet opening (not shown) thereof is substantially smaller than the openings of the tubes  50 ,  52  connected to the container  12 , thus achieving the desired vacuum effect. The venturi  54  illustratively provides a low pressure region in the center between converging and diverging portions thereof, thus creating vacuum when the pump  16  is in operation. The slurry  20  expelled through tube  52  into the slurry container  12  is then used to agitate the slurry  20  and maintain solids (not shown) in the slurry  20  forming the polishing compound in suspension, as desired to ensure proper abrasive effect of the slurry  20 . The vacuum created by the venturi  54  in cooperation with the pump  16  is further propagated to the tool  24  (to circulate slurry  20  therethrough) by acting on a tube  56  having a first end mounted to the low pressure region of the venturi  54  and a second end attached to a “Y” fitting  58 . 
     Still referring to  FIG. 4 , the Y fitting  58  is in turn connected to the vacuum and draw tube  46  as well as to another tube  60 , which is illustratively attached from underneath the container lid (reference  18  in  FIG. 2 ) to the vacuum gauge  22  and the vacuum bleed valve  62 . In this manner, the slurry  20  is only pumped from the slurry container  12  through the tube  40  when the vacuum bleed valve  62  is in the closed position, thus ensuring maximum pressure through the tube  40 . In particular, the amount of vacuum being drawn (and accordingly the flow of slurry  20 ) as well as the force holding the lower surface of the housing  28  against the glass can illustratively be regulated by opening the vacuum bleed valve  62  and adjusting an opening of the latter to vary the level of vacuum pressure. The vacuum created at the venturi  54  thus creates a vacuum in the intake tube  40  to draw the slurry  20  into the housing  28  in a conventional manner. A quantity of slurry  44  accumulates into the housing  28  and is subsequently removed therefrom into the venturi  54  and discharged (along with the slurry discharge from the pump  16 ) back into the slurry container  12 . As the slurry  44  is pulled through the vacuum and draw tube  46 , vacuum is further created in the housing  28  due to the action of the seal  32 , thus promoting circulation of the slurry  20  and maintaining a constant supply of slurry  44  in the interior of the housing  28  to keep the tool  24  in operation. 
     Still referring to  FIG. 4 , the adapter  42  illustratively comprises three (3) Allen screw locks including two (2) rubber washers (none shown) applied to the drive shaft (not shown) mounted within the housing tube  34  for driving the polishing pad  30 . In this manner, an increase of vacuum pressure of an extra four (4) inches can be achieved on the mercury gauge  22  due to reduced losses. Thus, the adapter  42  allows to overcome the problem of conventional prior art systems, in which a constant loss of pressure within the tool  24  is typically incurred due to leakage at the connection between the slurry intake tube as in  40  and the tool  24  and eventually results in malfunctioning of the tool  24 . 
     Referring now to  FIG. 5   a ,  FIG. 5   b , and  FIG. 5   c , according to alternative embodiments of the present invention, the pump  16  may be placed at different positions relative to the slurry container  12 , as long as the pump  16  is isolated from the slurry  20 . For example, instead of being positioned to a side of the slurry container  12  as illustrated in  FIG. 4 , the pump  16  may be suspended inside the slurry container  12  above the surface of the slurry  20  (see  FIG. 5   a ). Alternatively, the pump  16  may be positioned externally underneath the slurry container  12  (see  FIG. 5   b ). Also, the pump may be shelled away from the slurry container  12  within an outer container  64 , which illustratively holds the slurry container  12  therewithin, so that the pump  16  is isolated from the slurry  20  by the outer surface of the inner slurry container  12  (see  FIG. 5   c ). 
     Referring back to  FIG. 1 , the pump  16  is illustratively a dual purpose oil-filled pump (e.g. of the Little Giant® model) having a rating of 525 Gallons per hour (GPH) for a slurry container  12  of between two (2) and 60 gallons. With such a rating, maximum vacuum circulation can be achieved throughout the entire system  10  with stable average rate readings measured on the gauge  22  from about 17 inches of mercury up to 20 inches. Such a pump  16  could be used with a slurry intake tube  40  of up to 50 feet. The size (i.e. the ratings) of the pump  16  is selected in consideration with the size of the slurry container  12 : for a larger slurry container  12 , it is desirable to use a more powerful pump  16  capable of carrying a higher vacuum pressure. 
     Still referring to  FIG. 1 , the heatless slurry system  10  may also be used with two (2) pumps as in  16 . In this case, the elements of the system  10  are doubled except for the container  12 , the water tank  14  and the fining/grinding/polishing tool (reference  24  in  FIG. 4 ). The second pump as in  16  would be connected via a splitter (not shown) to the existing slurry container  12  and water tank  14  and would enable a higher vacuum pressure (e.g. up to 23 inches of mercury on the gauge, reference  22  in  FIG. 4 ) to be achieved. With two (2) pumps as in  16  connected in this manner, it then becomes possible to achieve such pressure readings using a slurry intake tube (reference  40  in  FIG. 4 ) having a length up to about 100 feet to connect the tool  24  to the pump  16  and slurry container  12 . Additional pumps as in  16  may further be added to a single slurry container  12  containing up to 60 gallons of slurry (reference  20  in  FIG. 4 ) in order to increase the vacuum pressure within the slurry container  12  up to a desired level, thus improving the performance of tool  24  and as such that of the overall system  10 , including additional operational modules, while still providing adequate manageability to the operator or operators. In particular, using additional pumps as in  16  enables a plurality of operators to each connect a tool  24  to a single slurry container  12 , thus allowing a plurality of operators to perform fining/polishing/grinding work at once. 
     Still referring to  FIG. 1 , in addition to decreasing costs due to the simplicity of the design, the heatless slurry system according to the present invention is advantageously more efficient than prior art slurry systems. Indeed, the system  10  improves agitation of the slurry  20  by ensuring an even flow in the slurry container  12  while at the same time achieving a stable vacuum pressure therewithin. More importantly, positioning the pump  16  externally with respect to the slurry container  12  overcomes most of the heating problem associated with conventional slurry systems. Indeed, in known systems, the heat produced by the working pump as in  16  is transferred to the slurry (reference  20  in  FIG. 4 ) since the pump  16  is typically submerged into the slurry container  12 . However, when the slurry  20  reaches a certain temperature, it loses its ability to remove scratches and the use of the tool (reference  24  in  FIG. 4 ) must be stopped to replace the slurry  20 . It is therefore desirable to evacuate the heat produced by the operating pump  16 . Indeed, it has been discovered by the present inventors that such heat represents the major part (e.g. 80%) of the heat problem faced by conventional slurry systems. Accordingly, the external location of the pump  16  advantageously enables the heat produced by the pump  16  to be evacuated in the air. Alternatively, the pump  16  may be removed or isolated or insulated from the abrasive solution  20  to achieve thermal isolation. As a result, an overheating of the abrasive polishing solution or slurry  20  is prevented and a less frequent change of the slurry  20  is required, thus decreasing the total amount of slurry  20  necessary. Therefore, when a larger area (reference  26  in  FIG. 4 ) needs restoring, less space is required to transport the slurry  20  onto the working site. Also, the restoration work becomes more efficient since the polishing or fining tool  24  can be used without interruption. 
     It should be noted that another way of reducing the heat in the slurry container  12  would be increase its size or volume. However, this poses transportation problems as the system would be too large to easily transport. 
     Advantageously, during operation of a system  10  according to a preferred embodiment of the present invention, the abrasive slurry solution  20  is returned back into the container  12  and agitates the abrasive slurry solution  20  within said container  12 . This is particularly useful as this avoids the need to use of a separate agitator. 
     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 as defined in the appended claims.