Patent Publication Number: US-2003226270-A1

Title: Level for indicating object tilt along user line of sight

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates generally to the field of levels which indicate the orientation of a surface relative to horizontal or vertical. More specifically the present invention relates to a level apparatus for indicating the tilt of an object surface toward or away from a user, or in other words along the user line of sight rather than across the user line of sight, such as for continuously indicating to a driver seated in a load-carrying fork lift truck the forward or rearward tilt of the truck to prevent hazardous forward or rearward instability, and for indicating to a construction worker whether an upright building element is truly vertical or is tilted toward or away from the worker. The level apparatus includes a fluid vessel containing an indicator fluid in the form of a liquid which preferably is pigmented for easy visibility, the fluid vessel having a vessel abutment region with a rearward abutment wall for placing flat against a surface to be evaluated for tilt and with a forward display wall including a fluid display window extending perpendicular to the user line of sight with a fluid level indicating mark, the fluid surface being visible in the fluid display window when the abutment wall is upright and the apparatus is thus oriented for use, and includes a vessel reservoir region extending either rearwardly or forwardly from the vessel abutment region along the user line of sight, the vessel abutment region and vessel reservoir region being in mutual fluid communication so that fluid in the vessel reservoir region either flows into or out of the vessel abutment region depending on the tilt of the level along the user line of sight. The vessel reservoir region contains a sufficient quantity of fluid that forward or rearward tilting of the rearward abutment wall a number of degrees considered significant for the intended use creates a readily apparent change in the position of the fluid surface in the fluid display window relative to the fluid level indicating mark to make the tilt of the apparatus and object surface noticeable to the user.  
       [0003] 2. Description of the Prior Art  
       [0004] There have long been levels for determining whether an upright surface of an object tilts to the left or to the right across the user line of sight. A problem with these prior levels has been that they do not indicate the tilt of an upright surface toward or away from the user, along the user line of sight. The user is forced to circle around an object, such as a post or column, to take a series of level readings, or two users must take simultaneous level readings, along perpendicular directions. What is needed is a level apparatus which indicates tilt toward or away from a user, and which can be structurally combined with or used in combination with a conventional level, to indicate the tilt of an upright member along and across the line of sight at the same time.  
       [0005] It is thus an object of the present invention to provide a level apparatus which indicates to a user the orientation of an upright object relative to vertical along the line of sight of the user.  
       [0006] It is another object of the present invention to provide such a level apparatus which can be structurally combined with or used in combination with a conventional level to simultaneously indicate the tilt of an upright object both along and across the user line of sight.  
       [0007] It is still another object of the present invention to provide such a level apparatus which is operable in a fully inverted position to be reversible and fit around a left hand corner or around a right hand corner of an upright object and give the user the level reading.  
       [0008] It is finally an object of the present invention to provide such a level apparatus which is simple in design, compact, light in weight, sturdy and inexpensive to manufacture.  
       SUMMARY OF THE INVENTION  
       [0009] The present invention accomplishes the above-stated objectives, as well as others, as may be determined by a fair reading and interpretation of the entire specification.  
       [0010] A level apparatus is provided for indicating the orientation relative to vertical of a surface of an object extending along a user line of sight, including a fluid vessel containing an indicator fluid including a liquid and having a fluid surface, the fluid vessel having a vessel abutment region with a rearward abutment wall for placing against a surface of an object to be evaluated for tilt and with a forward display wall including a fluid display window extending generally perpendicular to the user line of sight, the fluid surface being visible in the fluid display window when the abutment wall is substantially upright, and includes a vessel reservoir region extending at least one of: rearwardly and forwardly from the vessel abutment region along the user line of sight, the vessel abutment region and the vessel reservoir region being in mutual fluid communication so that the fluid in the vessel reservoir region flows into and out of the vessel abutment region depending on the tilt of the apparatus along the user line of sight and thereby alter the elevation of the fluid surface in the fluid display window; where the reservoir region contains a sufficient quantity of the fluid that substantial tilting of the abutment in one of a forward direction and a rearward direction creates a readily apparent change in the position of the fluid surface visible in the fluid display window to make the tilt of the apparatus and of the surface of the object noticeable to the user.  
       [0011] The fluid preferably is pigmented for easy visibility. The vessel abutment region and the vessel reservoir region are upright boxes which are joined in full fluid communication at box ends to form a vessel which is substantially L-shaped along a horizontal cross-section. The fluid display window optionally is a panel inset into a port in the display wall.  
       [0012] The level apparatus preferably additionally includes a fluid indicating mark on the display window for comparison with the position of the fluid surface. The level apparatus optionally includes several of the fluid level indicating marks to indicate the extent of apparatus and object surface tilt. The vessel abutment region and the vessel reservoir region optionally are each shaped substantially as hollow half circular cylinders.  
       [0013] The vessel alternatively is configured as a length of tube joined at its ends to form a continuous and substantially rectangular tube loop, the tube loop including upper and lower generally horizontal tube segments and first and second generally vertical tube segments, the tube being bent at opposing vessel region dividing points along the upper and lower horizontal tube segments to define on one side of the vessel abutment region and on the other side the vessel reservoir region, the tube containing the fluid.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014] Various other objects, advantages, and features of the invention will become apparent to those skilled in the art from the following discussion taken in conjunction with the following drawings, in which:  
     [0015]FIG. 1 is a perspective front view of the first preferred embodiment having an opaque housing with a transparent display window, the abutment and reservoir regions having the optional semi-cylindrical shape.  
     [0016]FIG. 2 is a perspective side view of the embodiment of FIG. 1 fitted against a surface of an upright object such as a column, the housing being transparent and revealing the indicator fluid with a fluid surface indicating an object surface tilt toward the display window/apparatus user.  
     [0017]FIG. 3 is a front view of a variation of the first embodiment, having the optional, conventional bubble tube sight glass level integrated into the forward display wall of the abutment region, to give level readings across the user line of sight as the reservoir region abuts the object.  
     [0018]FIG. 4 is a perspective view of the second embodiment having the tube loop, the tube loop having a transparent tube wall revealing the indicator fluid.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0019] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.  
     [0020] Reference is now made to the drawings, wherein like characteristics and features of the present invention shown in the various Figures are designated by the same reference numerals.  
     [0021] First Preferred Embodiment  
     [0022] Referring to FIGS.  1 - 3 , a level apparatus  10  is disclosed for indicating the orientation relative to vertical of a surface of an object toward or away from a user. Level apparatus  10  includes a fluid vessel  20  containing an indicator fluid F in the form of a liquid which preferably is pigmented for easy visibility, the fluid vessel  20  having a vessel abutment region  22  with a rearward abutment wall  22   a  for placing flat against a surface S to be evaluated for tilt and with a forward display wall  22   b  including a fluid display window  26  extending perpendicular to the user line of sight LOS with a fluid level indicating mark  32 , the fluid surface FS being visible in the fluid display window  26  when the abutment wall  22   a  is generally upright and includes a vessel reservoir region  24  extending either rearwardly or forwardly from the vessel abutment region  22  along the user line of sight LOS, the vessel abutment region  22  and vessel reservoir region  24  being in mutual fluid communication so that fluid F in the vessel reservoir region  24  either flows into or out of the vessel abutment region  22  depending on the tilt of the level along the user line of sight LOS. The vessel reservoir region  24  must contain a sufficient quantity of fluid F that forward or rearward tilting of the rearward abutment wall  22   a  a number of degrees considered significant for the intended use creates a readily apparent change in the position of the fluid surface FS in the fluid display window  26  relative to the fluid level indicating mark  32  to make the tilt of the apparatus  10  and object surface S noticeable to the user.  
     [0023] For one embodiment the vessel abutment region  22  and vessel reservoir region  24  are upright boxes which are joined in full fluid communication at box ends to form substantially an L-shape along a horizontal cross-section. Fluid display window  26  can be an inset transparent or translucent panel in the forward display wall  22   b  or the entire vessel  20  can be translucent or transparent. Either a single indicating mark  32  in the form of a horizontal indicating line or a vertical series of horizontal indicating lines  32  is preferably provided for comparison to the position of the adjacent fluid surface FS to indicate tilt and, where present, the degree of tilt. The vessel abutment and reservoir regions  22  and  24  each may be shaped substantially as hollow half cylinders.  
     [0024] A conventional sight glass level  34  optionally is inserted into a sight glass level port  36  in the forward display wall  22   b  so that apparatus  10  simultaneously indicates the tilt of an upright object relative to vertical both along and across the user line of sight. The sight glass level  34  takes its reading from apparatus  10  orientation resulting from abutment of vessel reservoir region abutment wall  24   a  with an upright side of the object which is perpendicular to the side of the object which the rearward abutment wall  22   a  abuts from which fluid display window  26  takes its reading. See FIG. 3. In other words the addition of the sight glass level  40  to apparatus  10  permits the user to determine whether an object leans toward or away from the user, and simultaneously to determine whether the object leans to one side or the other as viewed by the user.  
     [0025] Second Preferred Embodiment  
     [0026] For another embodiment fluid vessel  20  is a length of tube  40  joined at its ends to form a generally rectangular loop including upper and lower horizontal tube segments  42  and  44 , respectively, and first and second vertical tube segments  46  and  48 , the tube  40  being bent at opposing bend points P along upper and lower horizontal tube segments  42  and  44  to divide vessel  20  and define on one side of the bend vessel abutment region  22  and on the other side vessel reservoir region  24 , the tube  40  containing the indicator fluid F. See FIG. 4. Vessel abutment region  22  includes first vertical tube segment  46  which in part or in whole is either translucent or transparent to function as the fluid display window  26  and preferably has at least one fluid level indicating mark  32 . The vessel reservoir region  24  includes second vertical tube segment  48  which receives added fluid F when fluid F flows out of vessel abutment region  22  during backward apparatus  10  and object surface S tilting and releases subtracted fluid F during forward apparatus  10  and object surface S tilting. A tube  40  in the configuration of a continuous loop rather than a broken loop divided by closed ends or a barrier is preferred because air or other gas above the fluid F moves around loop  40  together with the fluid F so that no portion of the gas can become compressed during fluid F flow and thereby cause fluid flow resistance.  
     [0027] While the invention has been described, disclosed, illustrated and shown in various terms or certain embodiments or modifications which it has assumed in practice, the scope of the invention is not intended to be, nor should it be deemed to be, limited thereby and such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved especially as they fall within the breadth and scope of the claims here appended.