Abstract:
Apparatus is disclosed for repairing a flaw in a surface, partcularly in the field of vehicle glass repair. The apparatus has a housing adapted to engage the surface to be repaired, a repair seal for sealing between the housing and around the flaw to be repaired to define a repair space over the flaw. A reservoir communicates with the repair space and, in use, contains liquid repair material. A vacuum pump communicates with the repair space and the reservoir to apply a partial vacuum to the repair space and to the reservoir without repair liquid from the reservoir being drawn into the repair space in order to degas separately the flaw and repair liquid in the reservoir. After appropriate degassing, repair liquid from the reservoir is caused to flow into the repair space to fill the repair space with repair liquid.

Description:
This application claim the benefit of International Application No. GB9926864 1, filed on Nov. 12, 1999. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to apparatus for and methods of damage repair, more particularly but not exclusively in the field of repair of vehicle glass which is frequently chipped by flying stones or other material. The term “flaw” used herein is to cover chips defects or other surface faults. 
     BACKGROUND OF THE INVENTION 
     Existing apparatus and methods for repair of damaged vehicle glass involve subjecting a space around the area of damage to a partial vacuum to allow satisfactory penetration of an optically compatible resin into the area of damage, and extraction of air from the resin itself, curing the resin once the damaged area has been filled, and finishing the repair by removing excess cured resin and polishing the surface of the previously damaged area. 
     Problems which arise concern adequate degassing of both the damaged area and the resin. For example, the apparatus described in U.S. Pat. No. 4,419,3005 and U.S. Pat. No. 4,385,015 has a suction cup connected to a vacuum pump. A tube extends through the suction cup and seals against the surface of the glass around the flaw to be repaired. The inside of the tube communicates through a radial vacuum port with the space inside the suction cup. Resin is introduced into the tube and a piston is then introduced into the tube, at which time the vacuum pump acts on the flaw and the resin in the flaw to degas both the resin and the flaw. De-gasification in this way needs more time and is less effective, since gas from the flaw has to leave through the resin. 
     U.S. Pat. No. 4,776,780 describes a hand-operated suction cup through which a passage is provided for receiving repair liquid, such as a curable resin. The passage seals against the surface of the glass when a vacuum is applied to the suction cup, and the passage is completely isolated then from the suction cup interior. Resin is introduced into the passage and a piston is moved up and down in the passage to evacuate or pressurising the space within the passage. This apparatus encounters similar degassing problems described above. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, there is provided apparatus for repairing a flaw in a surface, which apparatus comprises: 
     housing adapted to engage the surface, 
     a repair seal for sealing between the housing and around the flaw to be repaired to define between the surface and the housing a repair space over the flaw, 
     a reservoir communicating with the repair space for containing liquid repair material, 
     vacuum means communicating with the repair space and the reservoir to apply a partial vacuum to the repair space and to the reservoir without repair liquid from the reservoir being drawn into the repair space in order to degas separately the flow and repair liquid in the reservoir, and means for causing repair liquid, in use, to flow from the reservoir into the repair space to fill the repair space with repair liquid. 
     The apparatus preferably includes means for exerting pressure on the repair space. 
     The invention further provides apparatus for repairing a flaw in a surface, which apparatus comprises: 
     a housing adapted to engage the surface, 
     a repair seal for sealing between the housing aid around the flaw to be repaired to define between the surface and the housing a repair space over the flaw, first vacuum means communicating with the repair space for applying a partial vacuum to the repair space, second vacuum means for applying an enhanced vacuum to the repair space, and 
     a reservoir for supplying repair liquid to the repair space. 
     The second vacuum means preferably comprises a piston slidably located in a bore in the housing, which bore communicates with the repair space. 
     The piston is preferably movable between a first position in which the partial vacuum applied by the vacuum means exists in the repair space and a second position in which the enhanced vacuum is applied to the repair space. 
     Valve means are preferably located in the housing between the first vacuum means and the second vacuum means such that when the second vacuum means is in use, the first vacuum means is isolated from the repair space. 
     The piston is preferably movable to a third position in which the bore and repair space are returned to external pressure, movement of the piston back towards the first position thereby exerting pressure on the repair space. 
     The piston positions are preferably defined by a cam extending from one of the piston and the bore wall, and a groove in the other of the piston and the bore wall to control piston travel within the bore. 
     The housing preferably includes an outer seal, the outer seal and the repair seal defining an annular space between the housing and the surface in use, the annular space having a connection to a vacuum source for reducing the pressure in the annular space to hold the housing to the surface in use. 
     The invention further provides a flexible patch for use with apparatus for repairing a flaw in a surface, which apparatus is of the type in which liquid repair material is introduced into a partly evacuated repair space adjacent the flaw, the patch being of gas and liquid impermeable sheet material and having a ring of adhesive on one side thereof for adhering to the surface around the flaw to be repaired, the patch including at least one slit therein within the ring of adhesive to allow liquid and gas to pass through the or each sit. 
     The patch preferably has two slits. 
     The adhesive ring is preferably of a thickness greater than 200 microns extending proud of the patch surface. A preferred adhesive ring thickness is 350 microns. 
     The invention further provides apparatus for repairing a flaw in a surface comprising a housing adapted to engage the surface, a repair seal for sealing between the housing and around the flaw to be repaired to define between the housing and the surface a repair space over the flaw, vacuum means communicating with the repair space for applying a partial vacuum to the repair space and a reservoir for supplying liquid repair material to the repair space, the reservoir comprising a capsule containing liquid repair material and a capsule holder in the housing, the capsule holder communicating with the repair space and including a release element for releasing liquid repair material from the capsule into the capsule holder when the capsule is inserted into the capsule holder. 
     The capsule is preferably cylindrical and includes an annular seal extending around the cylindrical outer surface thereof intermediate the ends of the capsule to form a seal with the interior surface of the capsule holder in the housing. 
     The capsule preferably includes an internal membrane to retain liquid repair material in the capsule, and the release element is preferably a spike to break the membrane when the capsule is inserted in the capsule holder. 
     When the liquid repair material is first released from the capsule into the capsule holder, the volume of the capsule holder is preferably sufficient to contain the liquid repair material without any liquid repair material reaching the repair space. 
     Upon full insertion of the capsule into the capsule holder, the repair space is preferably filled with liquid repair material. 
     The apparatus preferably includes a capsule position locating element on the housing for locating the capsule in a first position in which the liquid repair material is released and retained in the capsule holder or a second position in which the capsule is retained in a fully inserted position. The capsule preferably has a flange at the end thereof away from the end for insertion with the capsule holder, and the capsule position locating element is preferably an element spring biased to engage the flange to prevent movement of the capsule beyond the first position until moved inwardly, and engageable with the flange to prevent removal of the capsule when fully inserted, until moved inwardly towards the housing. 
     The invention further provides a method of repairing a flaw in a surface comprising the steps of forming a repair space adjacent the flaw; 
     applying a vacuum to the repair space and to liquid repair material while the liquid repair material is held outside the repair space; 
     introducing the liquid repair material into the repair space; 
     removing the vacuum applied to the repair space and then pressurising the repair space; 
     removing the repair space; 
     curing the liquid repair material until hard, and smoothing the repaired surface. 
     There is preferably an initial step of securing a patch over the flaw, the patch having a ring of adhesive surrounding the flaw, before forming the repair space, the patch being removed after curing the liquid repair material. 
    
    
     By way of example, one embodiment of apparatus and a method for repairing a flaw in a surface, together with an embodiment of a patch, according to the invention will now be described with reference to the accompanying drawings, in which: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of apparatus for repairing a flaw: 
     FIG. 2 is an underneath view of the apparatus of FIG. 1; 
     FIG. 3 is a sectional view of the apparatus of FIGS. 1 and 2 before commencement of a repair sequence; 
     FIG. 4 is a sectional view similar to figure after initial insertion of a capsule containing liquid repair material; 
     FIG. 5 is a sectional view of the apparatus after creation of an enhanced vacuum; 
     FIG. 6 is a sectional view similar to that of FIG. 5 with liquid repair material introduced above the flaw; 
     FIG. 6A shows in a view and position corresponding to FIG. 6, an alternative arrangement for retaining a capsule in its associated reservoir; 
     FIG. 7 is a sectional view of the apparatus with the vacuum released; 
     FIG. 8 is a sectional view of the apparatus with pressure applied to liquid repair material; 
     FIG. 9 is a plan view of a patch; 
     FIG. 10 is a sectional view of a patch along lines x—x in FIG. 9; 
     FIG. 11 is a side view illustrating a guide groove in a piston; and 
     FIG. 12 is a further side view of the piston of FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Apparatus for repairing a flaw in a surface is shown at  10  in FIG.  1 . The apparatus  10  is designed primarily for repairing flaws such as cracks or chips in glass, notably vehicle windscreens which are often subjected to impact from stones or other debris. 
     Apparatus  10  has a housing  11  machined from a solid block of polymeric material suitable for machining. The shape of the housing  11  is such that it would convenient to machine housing out of round stock of machineable polymeric material. 
     Internal features of the housing  11  will be described in more detail later but FIG. 1 shows a port  12  for connection to a vacuum pump, a handle  13  attached to a piston (described later) moveable up and down in a bore in the housing  11  and features at the base of the housing  11 , shown in more detail in FIG.  2 . 
     The base includes a peripheral elastomeric seal  14 , a poppet valve assembly  15  an O-ring seal  16  to form a seal around the flaw to be repaired and an opening  17  connected to the vacuum port  12  through a bore in the housing. The feature shown at  18  is a base portion of part of a resin capsule holder to be described later. The poppet valve assembly  15  is held in place by a pair of screws  19 ; base support  20  has cutouts  21  and  22  so that when rotated through 90°, the poppet valve assembly can be removed completely from the housing for cleaning. 
     FIG. 3 shows the apparatus  10  held by suction against laminated glass sheet  30  having a flaw  31  in it to be filled and repaired. The housing  11  is formed in two parts  32 ,  33  held together by a threadedly engaged retaining ring  34  and sealed by a gasket  36 . An O-ring seal  35  seals between the two housing parts  33  and  34  a piston  40  is moveable within a cylindrical bore  41  in the housing  11 . An O-ring  42  located near the base of the piston  40  seals between the piston  40  and the bore  41 . The piston  40  has a recess  43  at the base thereof designed to accept a top portion  44  of the poppet valve assembly  15 . The poppet valve assembly  15  has an annual portion  45  locating O-ring  46  which is biased by spring  47  to seal against valve seat  50 . When the piston  40  is fully down, the piston forces down the poppet valve to unseat the O-ring  46  to open the valve. 
     The housing is held in place by application of a partial vacuum from a vacuum pump (not shown) acting through the opening  17  in the annular space between the O-ring  16  and the seal  14 . The housing is held against the glass  30  in this way. 
     Before mounting the housing  11  on to the glass  30 , a clear patch of a suitable polymer is fixed over the flaw  31 . The patch is indicated at  60  and is shown in more detail in FIGS. 9 and 10. The patch  60  is a circular disc of a suitable polymeric material and carries an annular adhesive band  61  extending under the O-ring  16  when the housing  11  is in position. The patch  60  has a pair of slits  62 ,  63  to allow gas and liquid to pass therethrough. 
     As can be seen in FIG. 2, the material of the housing  11  inside the O-ring  16  if further away from the glass than the material of the housing outside the O-ring  16 . The O-ring  16  together with the glass and the material of the housing  11  defines a repair space  65 . 
     The bore  41  communicates with the repair space  65  through a passageway  70 . When the poppet valve  45  is open, there is communication between the repair space  65  and the annular space between the O-ring  16  and the external seal  14 . When the poppet valve is closed, the repair space  65  is isolated from the annular space between the O-ring  16  and the external seal  14 . 
     The housing  11  includes a holder  80  for holding a resin capsule  81 . The resin capsule  81  is of a suitable plastics material and has a cylindrical portion  82  carrying an O-ring  83  in a circumferential seat. The capsule  81  has a flared opening  84  at one end and an angular flange  85  at the end opposite the opening  84 . 
     The capsule holder  80  in the housing  11  is cylindrical and designed to accept the cylindrical portion of the capsule  85  with the O-ring  83  sealing against the inside of the holder wall  90 . The capsule  81  holds liquid repair material  86  retained by a membrane  87 . The holder  80  has a central spike  91  located in the material of the housing  11  and sealed with an O-ring  92 . When the capsule  81  is inserted into the holder  80  over the spike  91 , the spike breaks the membrane to release the resin  86  into the holder  80 . 
     The holder  80  defines an internal space in communication wish the repair space  65  through communicating bores  93 ,  94 . 
     A capsule position locating assembly  100  is mounted on the housing  11  and has a capsule position locating element  101  mounted on a spring  102  such that the element  101  can be pushed in in order to allow the flange  85  of the capsule  81  to pass. Operation of the assembly  100  and movement of the capsule  81  win be described in more detail in connection with the operating sequence, as will movement of the piston  40 . 
     Once the housing is held to the glass  30  over the flaw  31  and the patch  60  by application of a partial vacuum to the annular space between the O-ring  16  and the seal  14 , the capsule  81  is inserted into the capsule holder  80  until the capsule flange  85  engages the element  100 . During this operation, the spike  91  breaks the membrane  87  to release resin from the capsule into the capsule holder, as shown in FIG.  4 . At this stage the piston  40  remains at its lowest position and the poppet valve is open to cause the repair space  65  to be at the same reduced pressure as the annular space between the O-ring  16  and the seal  14 . Based on experimental tests, the apparatus should be kept in the state as described above with reference to FIG. 4 for about 1 minute and this will allow degassing of the flaw and partial degassing of the resin  86  in the resin holder  80 . It is important to note that the capsule  81  seals against the side of the capsule holder  80  by means of the O-ring  83  and the reduced pressure in the capsule holder  80  is therefore the same as the reduced pressure in the repair space  65 . 
     In order to carry out further degassing (degassing of the flaw should take place in a matter of seconds, but degassing of the resin is a much slower process) the piston  40  is raised a shown in FIG.  5 . Raising of the piston  40  causes closure of the poppet valve such that the poppet valve O-ring  46  seals against the valve seat  50 . In this way, the repair space  65  is isolated from the annular space between the O-ring  16  and the seal  14 . Raising of the piston  40  significantly enhances evacuation of the repair space  65  and the space at the base of the capsule holder  80 . Application of enhanced vacuum by raising the piston  40  should be for about 30 seconds. The piston position shown in FIG. 5 is intermediate its low position and the position for fully enhanced vacuum (the position shown in FIG.  6 ). 
     After the piston  40  has been held in the enhanced vacuum position (FIG.  6 ), the element  101  is pressed in to allow the capsule  81  to be inserted fully into the capsule holder until the element  101  can spring out over the flange  85  (FIG.  6 ). With the body of the capsule occupying the space in the capsule holder  80 , the resin  86  is forced through the bores  93  and  94  to the repair space  65  and into the passage  70  leading to the bore  41 . In this way, the repair space  65  is filled with the resin  86 , the flaw  31  and the resin  86  having been substantially degassed. Experimentation has shown that it is important to keep the position shown in FIG. 6 for about 30 seconds as it has been observed that the resin stream injected into the repair space  65  often contains many small bubbles, and a few larger ones, in spite of the previous degassing. Video evidence shows that these bubbles float slowly upwards into the overflow space but that it takes approximately 30 seconds to do so. 
     FIG. 6A shows a modified form of apparatus  10 , insofar as retention of the capsule in the reservoir is concerned. The capsule position locating assembly  100  is omitted, and a simpler form of location is provided. 
     Capsule  81 ′ is internally the same as the capsule  80  of FIG. 6, and lower cylindrical portion of the capsule  80 ′ engages holder  81 ′ in the same way as capsule  80  engages the holder  81  of FIG.  6 . However, the capsule  81 ′ has a non-circular flange  85 ′ (in the embodiment shown, of oval shape, although other shapes are possible), in contrast to the circular flange of the capsule  85  of FIG. 6, and the housing  11  has a groove  200  formed therein of dimension to accept and locate the flange  85 ′ when the capsule is twisted to move the wider part of the flange  85 ′ into the groove  200  (as shown in FIG.  6 A). When oriented such that the narrower part of the oval flange  85 ′ is adjacent the groove  200 , the flange can pass the housing without contact to allow the capsule to slide into or out of the holder  80 ′. 
     The insertion steps of the capsule  81 ′ are similar to those described in relation to FIGS. 3 to  6  for the capsule  81 . The capsule  81 ′ is first inserted sufficiently into the holder  80 ′ to break the capsule seal  87  and release the resin into the reservoir. Oriented with the wider part of the flange  85 ′ towards the housing  11 , the flange  85 ′ engages a shoulder on the housing to locate the capsule  81 ′ in a position similar to that of FIG.  4 . Rotation of the capsule  81 ′ such that the narrower part of the flange  85 ′ extends towards the housing  11  allows the capsule to be inserted fully into the holder  80 ′, and twisted again until the wider part of the capsule flange  85 ′ enters the groove and is located thereby to hold the capsule  81 ′ in the fully engaged position (FIG.  6 A). The capsule  81 ′ can be withdrawn simply by rotating to disengage the flange  85 ′ from tee groove  200  and withdrawing the capsule  81 ′ from the holder  80 ′. 
     The next stage is to release the vacuum in the bore  41  by raising further the piston  40  until the O-ring  42  rises above an exhausting groove  110  extending downwardly into the bore  41  from the upper end thereof. The poppet valve remains closed so that the housing  11  remains attached to the glass  30  but the bore  41  and the repair space  65  are returned to atmospheric pressure (FIG.  7 ). 
     It is now important to ensure that the resin  86  is filling the entire space of the flaw  31 . In order to urge the resin  86  into the flaw  31 , the piston  41  is pushed down into the bore  40  once again, causing air in the bore  41  to be compressed and to exert pressure on the repair space  65 , thereby ensuring that the flaw  31  is filled with resin. The pressure phase (FIG. 8) requires a significant time to ensure that the flaw  31  is completely filled. While some flaws fill very quickly, others seem to be much slower to fill. Even cracks that seem not to be filling properly sometimes respond to extremely long pressure phase times. For this reason, it is appropriate for the pressure phase to be at least 3 minutes. In the pressure phase, the piston  40  does not engage the poppet valve, which remains closed so that a vacuum is retained in the annular space between the O-ring  16  and the seal  14  while pressure is exerted on the repair space  65 . 
     After completion of the pressure phase, the vacuum pump is turned off to release the vacuum in the annular space between the O-ring  16  and the seal  14  and the apparatus  10  can be removed carefully from the glass  30 . At this stage, any excess resin can be wiped away and, if a UV curing resin is used, a UV source can be played on the resin retained in the flaw  31  by the patch  60  until hardened. The patch  60  can then be removed and the hardened resin levelled so that an unblemished surface due to filling of the flaw  31  is produced. The area can the be polished and, with a resin of an appropriate optical characteristic to match that of the glass  30 , an effective repair would have been cried out. 
     Positions of the piston  40  in the bore  41  are defined by engagement of a pin (not shown) into the bore  41  from the bore wall with a cam track  120  formed in the piston external surface. FIGS. 11 and 12 show the nature of the cam track  120 . The fully inserted position is shown where the pin engages the cam track a  121 . The piston is then rotated and pulled out to reach the vacuum enhancing position shown in FIG. 6, when the pin engages circumferential section  122  of the cam track. Vacuum release position (at maximum piston height) is achieved when the pin engages the cam track ax  123 . The piston is then twisted and returned to a lowered (but not fully lowered) position is shown in FIG. 8 where the pin engages the cam track at  124 . To give an operator an audible or tangible indication of a particular position, cam track may have locating positions of increased depth and the pin may be spring loaded to engage the positions of increased depths and thereby indicate to an operator that a particular position has been reached. 
     This embodiment of a method and apparatus according to the invention provides significant advantages over the existing apparatus and methods, notably that provision of enhanced vacuum improves degassing efficiency, application of enhanced vacuum to both the flaw and resin while the resin is separated from the flaw maximises the opportunity for the flaw to be evacuated properly. This enables substantial reduction in the time required for degassing to take place and a considerable increase in both efficiency and effectiveness of the repair. The system is designed to provide an initial roughing vacuum produced by the vacuum pump of 20 kPa absolute, pressure being reduced during the enhanced vacuum stage to 10 kPa absolute. During the pressure cycle, pressure is increased to 400 kPa absolute (these figures are based on calculations involving the volumes involved and do not allow for possible leakage. The values have not been measured experimentally). 
     Use of a patch has been found to be particularly effective; previous methods involved application of resin to a flaw and subsequent covering of the resin by a cover strip before curing. The presence of a patch from the start of the operation ensures minimum disturbance to the resin during the operation and during curing. 
     Use of a resin capsule minimises the risk of contact between the resin and the skin of an operator, as does the use of the patch. 
     It will be appreciated that modifications to the apparatus and matters may be the scope of the invention being defined in the appended claims.