Patent Publication Number: US-7587872-B2

Title: Telescoping chair for supporting bars

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application is a Non-Provisional Utility application which claims benefit of co-pending U.S. Patent Application Ser. No. 60/899,525 filed Feb. 5, 2007, entitled “Telescoping Chair For Supporting Bars” which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   Reinforced concrete construction frequently utilizes reinforcing bars suspended within the concrete. Often these bars are suspended on chairs at specified heights. The present invention relates generally to a chair for suspending bars within reinforced concrete. The chair can be used to support reinforcing bars as well as other long bodies, such as pipes, ducting or conduit. 
   2. Description of the Prior Art 
   Reinforced concrete construction has been around for many years. Reinforcing bars are embedded in the concrete to improve the strength of the final concrete. Concrete has a very high compressive strength, but the tensile strength is improved significantly by utilizing reinforcing bars within the concrete. These reinforcing bars are typically suspended at a specified height which varies from one job to the next depending on the concrete specifications for each job. In the past, metal chairs have been used to support the bars; however metal chairs have many disadvantages. Metal at the bottom of the chair is exposed and provides an initiation point for rust. This rusting causes the chairs to expand because the metal oxide takes up a larger volume than the metal. As the rusting chair expands, the concrete cracks and the concrete structure is weakened. 
   There are many chair designs in existence today. For example, Liuzza, in U.S. Pat. No. 4,060,954, discloses a base plate with lugs for receiving the legs of a chair. The height of the support is varied by stacking one chair on another. In a stack of these chairs, bars can be supported on each chair so that bars can be simultaneously supported at several different elevations within the stack of chairs. 
   Vigh, in. U.S. Pat. No. 4,080,770, discloses a plastic base and a metal wire spacer. The metal wire spacer is received in the plastic base. The plastic base may have tabs which can be used to secure the base to a substructure. The bars are supported at different heights by inserting different size wire spacers into the plastic base. 
   U.S. Pat. No. 4,835,933 by Yung discloses a support that has a base and a central vertical post that ends in a saddle, wherein the saddle is adapted for receiving a bar. A separate clamp member has arms and is received in holes in the saddle, wherein these holes are beside the central post. The arms of the clamp member hold the first bar and hooks in the clamp member hold the second bar transverse to the first bar. Different size supports are used to hold bars at different heights, and small adjustments can be made by placing an extender on top of the saddle portion of the support. 
   Lowery, in U.S. Pat. No. 5,595,039, discloses another chair. This chair has a base and a cap which are connected by a stem. The stem can be rebar, which is available at most job sites. The cap has a slot for holding the reinforcing bar and the height of the support can be adjusted by cutting the stem to the desired size. Thus, the stem can be cut at the job site to position the bar at the correct height. 
   Verelli et al., in U.S. Pat. No. 6,354,054, discloses a rebar chair with a body and four legs below the body. Two transverse bars are received between the four legs and are wired to the body or are supported on another chair of a different design placed between the legs. At least a third bar can be received in a saddle on top of the body. 
   U.S. Patent Published Application Number 2004/0261352 A1 by Bennett et al. discloses a support chair with a tapered body and a plurality of legs. The body is generally tapered so that the legs get further apart as they get lower, and there are notches on top of the body to hold transverse bars. The body is designed so additional chairs can be stacked on top of the supporting chair to adjust the height at which the bars are supported. 
   Screed supports are also used in concrete construction to level a concrete slab. Pilj, in U.S. Pat. No. 1,852,673 discloses a screed support which has a post and a separate support section. The post is driven into an underlying base, and the support section is attached to the post. The height of the support is adjusted by attaching the support at different positions on the post. The support is adapted to receive a leveling device for leveling the concrete. 
   Another screed support is disclosed by Cox in U.S. Pat. No. 2,551,826. Cox describes a post with a bottom portion which is adapted to be attached to an underlying base. The bottom of this post is pointed and threaded so that it can be screwed into the underlying base. A separate saddle has a sleeve which is slid over the top of the post. The height of the saddle is determined by sliding a nail through nail holes in the sleeve wherein the nail is engaged in notches in the post. The saddle is adapted to receive a leveling device. 
   Hillberg, in U.S. Pat. No. 3,006,115, describes another screed support. This screed support also has two parts. The first is a base which supports a socket and the second part is a cradle. The cradle has a threaded shank with an adjusting nut. The shank fits into the socket and the height of the cradle is set by the adjusting nut which abuts the socket. The cradle is adapted to receive a straight edge or a bar for leveling the concrete. 
   BRIEF SUMMARY OF THE INVENTION 
   The current invention comprises a chair for supporting bars in concrete. The chair is comprised of a series of concentric telescoping sections which lock when telescoped to an extended position. Each section is locked independent of the others so that if the chair had three sections, the top section could be extended and locked in place while the intermediate section remained collapsed relative to the bottom section. 
   Three embodiments of the lock are described. The first consists of a protrusion and a J slot. The protrusion is defined in a first section and the J slot is received in a second section wherein the first and second sections are adjacent so that one extends from the other. The protrusion is engaged in the J slot and as the sections are extended the protrusion slides up and finally catches in the end of the J slot. The end of the J slot forms a catch point and when the chair is upright, gravity pushes the protrusion into the catch point, thus locking the sections in an extended position. 
   A second embodiment of the lock is comprised of a detent and indentation. The detent is defined in a first section and the indentation is in a second, adjacent section. When the sections are extended relative to each other, the detent engages the indentation so as to lock the sections in the extended position. 
   The third embodiment of the lock comprises a spring tab defined in a first section and a window defined in a second section. The spring tab engages the window when the sections are extended relative to each other, so the sections lock in the extended position. 
   There is also a retaining ring which is attached near the top of the top section. This helps to keep the sections together so they do not fall apart before being positioned. The top section has a seat defined in it for receiving the bar, and the bottom section has a base extending horizontally to increase the stability of the chair. 
   The current invention provides several advantages to the user, such as the need for only one chair to support a bar at a variety of heights. This allows the store room to only stock one chair, which reduces inventory and thereby lowers cost. The chair is also very easy to use and the height can be adjusted in the field when the bars are being supported. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of the chair with the J slot lock. 
       FIG. 2  is an exploded perspective view of the chair with the detent lock. 
       FIG. 3  is an exploded perspective view of the chair with the spring tab lock. 
       FIG. 4  is a perspective view of the chair with the spring tab lock in the locked position. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The preferred embodiment of the chair  10  is shown in an exploded perspective view in  FIG. 1 . The chair  10  is comprised of concentric sections which telescope between a collapsed position and an extended position. In the preferred embodiment, three sections are utilized, including a top section  12 , an intermediate section  14 , and a bottom section  16 . The top section  12  is received in the intermediate section  14 , which is received in the bottom section  16  so that all three sections are received together one after the other. It is also possible that the chair  10  comprise only top and bottom sections  12 ,  16 , or more than three sections with a plurality of intermediate sections  14 , as needed. 
   Generally, the chair  10  is used to support bars that are to be encased in concrete, so the chair  10  is also encased for the life of the concrete. Chairs  10  are placed under the lowest bars which become the supporting bars. Crossing bars are then placed on top of the supporting bars, and are supported by the supporting bars. Of course, more than just the lowest bars could be supported, up to all of the bars used, as needed. The chair  10  is comprised of plastic, which does not provide an access point for rust to begin in the concrete. This helps to sustain the soundness and strength of the concrete over a longer period than if a metal support were used. 
   In the preferred embodiment the sections all have a common axis, and the axis is vertical when the chair is upright. Each section can be extended independent of the others so that the top section  12  could be extended relative to the intermediate section  14  at the same time that the intermediate section  14  was collapsed relative to the bottom section  16 . It is just as possible to have every section extended or every section collapsed. So, the height at which the chair  10  supports a bar depends on which sections are extended. 
   Preferentially, the shape of each section is cylindrical. Depending on the type of lock used, the sections could also be squares, rectangles, ovals or almost any other shape which is able to extend or telescope relative to an adjacent shape. To effectively support a bar at a variety of heights, the sections have to lock when extended relative to each other. Therefore, the chair  10  has at least one lock, and preferentially a plurality of locks, such that the sections lock in the extended position. Of course, there is at least one lock for each extending section. 
   Three embodiments of the locks utilized are described. The first embodiment comprises protrusions  18 A and  18 B which are received in J slots  20 B and  20 C. Similar components on different sections are given different suffixes for clarity, with the top section having the suffix A, the intermediate section having the suffix B, and the bottom section having the suffix C. Therefore, the top section protrusion is designated as  18 A, and the intermediate section protrusion is designated as  18 B. Each telescoping portion of the chair  10  involves a first and a second section, where one of the sections extends relative to the other section. The extending section can be either the first or the second section wherein the supporting section is the other section. Therefore the intermediate section  14  could serve as a supporting section for the top section  12 , and at the same time the intermediate section  14  could serve as an extending section for the bottom section  16 . Throughout this disclosure the terms first and second sections, or alternatively the extending and supporting sections, are used to refer to any two adjacent sections. The J slot is also referred to as the slot. The embodiments of the lock are described for the top and intermediate sections, but apply to all the sections. 
   In the preferred embodiment at least one protrusion  18 A, and preferably two, are defined in each extending section. At least one J slot  20 B, and preferably two, are defined in each supporting section such that the J-slot  20 B receives the protrusion  18 A of the extending section. One end of the J slot  20 B comprises an opening  22 B wherein the other end comprises a catch point  24 B. Preferentially, the opening  22 B is received at the bottom end of the supporting section  26 B. The catch point  24 B is angled such that the protrusion  18 A is urged into the catch point  24 B when the protrusion  18 A is engaged in the catch point  24 B and the chair  10  is upright. Gravity serves as the force which urges the protrusion  18 A into the catch point  24 B. When the protrusion  18 A and J slot  20 B locking mechanism is used, the sections comprise cylinders to allow the extending section to rotate in the supporting section. As the extending section is extended the protrusion  18 A remains engaged in the J slot  20 B, which requires the sections to rotate within each other. 
   During assembly, the top section  12  is inserted into the intermediate section  14  from the bottom such that the protrusion  18 A engages the J slot  20 B. Then the intermediate section  14  is inserted into the supporting bottom section  16  from the bottom, again with the protrusion  18 B engaging the J slot  20 C. The J slot opening  22 B is on the bottom end  26 B of the supporting section. The opening  22 B provides a location where the protrusion  18 A can be introduced into the J slot  20 B when the sections are assembled. As can be seen, the J slot  20 B and protrusion  18 A could be reversed, so the protrusion  18 A was in the supporting section and the J slot  20 B was in the extending section. If the J slot  20 B were in the extending section, the J slot opening  22 B would be in the top end  28 B of the sections having the J slots. Regardless of which section has the protrusion  18 A and the J slot  20 B, the top or extending section  12  is introduced to the intermediate or supporting section  14  from the bottom during assembly. 
   It is also possible to construct the chair  10  with the bottom section  16  being smaller and received inside the intermediate section  14 . Then the top section  12  would be even larger and the intermediate section  14  would be received inside the top section  12 . The locking function would still operate in the same manner. 
   A second embodiment of the lock comprises detents  30 D,  30 E and indentations  32 E,  32 F as shown in  FIG. 2 . In the second embodiment, the top section is designated by the suffix D, the intermediate section by the suffix E, and the bottom section by the suffix F, similar to the first embodiment. The components in the embodiment shown in  FIG. 2  are distinguished from similar components in the embodiment shown in  FIG. 1  by the suffix G when the suffix of D, E, or F is not appropriate, so the chair in  FIG. 2  is labeled  10 G. The detent  30 D is the projection which is received in the associated indentation  32 E. The detent  30 D is defined in a first section, and the indentation  32 E is defined in a second section such that the detent  30 D engages the indentation  32 E when the sections are extended relative to each other. This serves to lock the sections in the extended positions. In the preferred embodiment, the sections are cylinders, and each extending section has two detents  30 D. The supporting sections have one indentation  32 E going all the way around on the inside. 
   When the detent  30 D and indentation  32 E lock system is used, the sections could be a variety of shapes. They could be square, oval, rectangular or any other shape which is able to slide up and down within an adjacent shape. There is no need for the detent  30 D to engage the indentation  32 E until the sections are completely extended, so the sections don&#39;t need to rotate within one another. Therefore, there is no need for cylindrical shaped sections. If a non-cylindrical shape were used, there would be one indentation  32 E positioned above each detent  30 D so the sections would lock when extended. For any shape used, there could be any number of detents for each locking section. 
   The detent  30 D is constructed such that it can be released from the indentation  32 E if desired. The detent  30 D is on the end of a finger  31 D which urges the detent  30 D into the indentation  32 E. By pressing in on the finger  31 D, the detent  30 D can be disengaged from the indentation  32 E, which allows a section to be collapsed after it has been locked in the extended position. 
   The third embodiment of the lock comprises a spring tab  44  defined in the top section  12 H and a window  46  defined in the bottom section  161 , as shown in  FIGS. 3 &amp; 4 . Comparable components in  FIGS. 3 &amp; 4  are designated by the suffix J, with the top section components having the suffix H and the bottom section components having the suffix I, as described for the detent lock system. Preferably, each extending section is secured by two spring tab locks, but any number of locks are possible. 
   The spring tab  44  engages the window  46  and locks the sections when extended relative to each other. The spring tab  44  naturally sits in the position held when engaged with the window  46 , so the resiliency of the spring tab  44  presses outward when the spring tab  44  is held inside of the bottom section  16 I. The window  46  passes completely through the bottom section  16 I, so the spring tab  44  is accessible from outside the bottom section  16 I when the sections are locked. In the preferred embodiment, the spring tab  44  has a step  48  to more securely engage the window  46 . In the locked position, the step  48  extends below the window  46  on the outside surface of the bottom section  16 I. Once locked, the sections  12 H,  16 I can be unlocked by pulling the top section  12 H upwards until the step  48  no longer extends below the window  46 , then pressing the spring tab  44  and step  48  inward past the inner surface of the bottom section  16 I, and then pushing the top section  12 H down. 
   As with the detent lock, the position of the spring tab  44  and the window  46  could be reversed, with the spring tab  44  in the bottom section  16 I and the window  46  in the top section  12 H. The sections could be a variety of shapes, and there could be more than two sections. For both the spring tab and detent lock system, inserting extending sections into supporting sections from the bottom simplifies assembly by avoiding engagement of the lock. 
   To more securely receive a bar, the chair  10  has a seat  34  defined at the top end  28 A of at least one section, as shown in  FIG. 1 . Of course, the seat  34  can also receive conduit, tubing, or other generally rod-shaped objects. Preferentially, the seat  34  comprises two concave recesses adapted to receive a reinforcing bar. These concave recesses are on opposite sides of the top end  28 A of the top section  12 . It is also possible that the seat  34  would comprise concave recesses received on more than just the top section  12 . In fact, the seat  34  could be defined in the top end of every section  28 A,  28 B, and  28 C. The recesses would have to be aligned when the sections were collapsed so that the bar would fit into all of the recesses at one time. As each section was extended, the recesses would be available at the top of the chair  10 . It is also possible for the seat  34  to be something other than concave recesses, such as fingers extending upwards from the top end  28 A of a section to hold the bar. 
   In the preferred embodiment the seat  34  comprises concave recesses in only the top section  12 . In this case, the top section  12  always has to be the highest section when the chair  10  is upright. A retaining ring  36  insures the top section  12  is the highest section. The retaining ring  36  is connected near the top end of the top section  28 A, just below the seat  34 . The retaining ring  36  is dimensioned to abut the intermediate and bottom sections  14 ,  16  so that the top end of the top section  28 A is always higher than the other sections. Keeping the seat  34  above the other sections prevents the intermediate and bottom sections  14 ,  16  from interfering with the placement of the bar in the seat  34 . 
   A second purpose of the retaining ring  36  is to prevent the sections from separating. The distance from the retaining ring  36  to the top section protrusion  18 A is less than the distance from the top end  28 B to the bottom end  26 B of the intermediate section  14 . Because the retaining ring  36  abuts the top end of the intermediate section  28 B, the protrusion  18 A has to remain engaged in the J slot  20 B, and the sections cannot separate. After the top section  12  is introduced into the intermediate section  14  from the bottom, and the rest of the chair  10  is similarly assembled, the retaining ring  36  is attached to the top section  12 . The retaining ring  36  can be a wide variety of shapes, as long as it abuts the intermediate and bottom sections  14 ,  16 . Also, the retaining ring  36  can be connected to the top section by any appropriate means, such as a tab and groove or glue. The retaining ring  36  includes at least one, and preferably two, finger notches  37  to facilitate handling. The finger notches  37  are defined in the retaining ring  36 , and are dimensioned to receive a human finger. 
   A base  38  is used to stabilize the chair  10 . The base  38  is connected at the bottom end of the bottom section  26 C. The base  38  is perpendicular to the central axis of the sections, so that when the chair  10  is upright, the base  38  is horizontal. The base  38  can be connected to the bottom section  16  by any appropriate means, including a tab  40  and groove  42 , wherein the tab  40  is inserted into the groove  42  and then rotated to a locked position. The base  38  can be any of a variety of shapes. It can be a round disk, or a plurality of legs extending from the bottom section  16 , or any other shape which would provide support to the chair  10 . The base  38  can extend inside of the bottom section  16  by passing under the bottom end  26 C, or it can just be attached to the outer surface of the bottom section  16 . If the base extended under the bottom end of every section  26 A,  26 B, and  26 C, it could be utilized to prevent the chair  10  from coming apart by preventing the extending sections from falling out of the bottom of the supporting sections. 
   The current invention also includes a method for supporting a bar. This method includes providing the chair  10  as described above, and extending the chair  10  to an extended height as desired. The chair  10  is then locked in the extended height and positioned below the bar to be supported. The seat  34  defined in the chair  10  is engaged with the bar when the chair  10  is positioned below the bar. Finally, the bar is supported at the extended height by the chair  10  underneath the bar. The chair  10  is stabilized by the base  38  which extends from the bottom section  16  of the chair  10 . The sections can be locked in an extended position by engaging a protrusion  18 A defined in one section with a slot catch point  24 B defined in anther section. 
   Thus, although there have been described particular embodiments of the present invention of a new and useful Telescoping Chair for Supporting Bars, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.