Abstract:
A C-shaped clamp having elongated flanges at its ends defining the open portion of the &#34;C&#34;. A bolt is inserted through holes provided in the flanges. A nut tightened on the bolt against one of the flanges compresses the C-shaped clamp. A U-shaped key slideably fitted in a lengthwise slot in the threaded end of the bolt engages the inside wall of one flange and the outwardly facing side of the nut and pulls the flanges apart when the nut is loosened on the bolt thus expanding the C-shaped clamp.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to electrical cable connector clamps and, more particularly, to self-expandable connector clamps utilized with lead storage batteries. 
     It is well known in the art to utilize ring or C-shaped electrically conductive clamps to connect high current capacity cables to the terminals of electrical storage batteries and the like. The prior art clamp is typically a C-shaped clamp utilizing a bolt and nut assembly to compress the clamp around the battery terminal thus retaining the clamp securely in place on the battery terminal. To remove the clamp from around the battery terminal the nut is loosened thus allowing the C-clamp to be expanded and removed. Since the clamp is typically fabricated from a relatively soft, plastic or pliable material that retains its shape, it is necessary to manually expand the clamp after the nut has been loosened, prying open the C-clamp with the blade of a screw driver, for example, or using a special tool or wrench. 
     Accordingly, it is a primary object of the present invention to provide a battery terminal clamp which is self-expanding and thus removable when the securing nut has been loosened without further manipulation of the clamp or its component parts. 
     It is another object of the present invention to provide a self-expandable battery terminal clamp which is simple and inexpensive in construction. 
     SUMMARY OF THE INVENTION 
     In accordance with the principles of the present invention, a self-expandable battery terminal clamp comprises a C-shaped clamp having slightly extended, flattened end portions which define the open portion of the C-shaped clamp with a bolt inserted through holes provided in the end portions and a nut which compresses the clamp when it is tightened on the bolt. The threaded portion of the bolt is slotted to receive an elongated U-shaped key such that when the U-shaped key is installed, the nut is coupled to one flattened end portion of the C-shaped clamp. As the nut is loosened on the bolt, the flattened end portion of the clamp will be pulled outwardly by the nut thus expanding the clamp and allowing it to be removed from a battery terminal. 
     Other objects and features and a more clear understanding of the present invention will become apparent from the detailed description taken in conjunction with the accompanying drawings, in which like reference numbers refer to like parts as illustrated in the different figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of a battery terminal clamp according to the principles of the present invention; 
     FIG. 2a is a sectional view taken along line A-A&#39; of the battery terminal clamp shown in FIG. 1; 
     FIG. 2b is a sectional view taken along line A-A&#39; of the nut and U-shaped key shown in FIG. 1; 
     FIG. 2c is a sectional view taken along line B-B&#39; of the battery terminal clamp shown in FIG. 1 illustrating the clamp installed on a battery post; 
     FIG. 3 is a top plan view of a battery illustrating the battery terminal clamp of FIG. 1 installed; and 
     FIG. 4 is a sectional view taken along line B-B&#39; of the battery and battery terminal clamp shown in FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1, 2a and 2b, a self-expandable battery cable clamp 10 constructed in accordance with the principles of the present invention is shown. A C-shaped clamp 1 having elongated or extended and flattened end portions or flanges 3 and 5 which define the open portion 7 of the C-shape is formed from lead or other suitable, electrically conductive material. The material should be relatively soft and pliable or easily deformed when used for electrical applications such a battery cable clamp 10. The clamp 10, when fabricated from a material having sufficient tensile strength may also be used to connect cables or rods to posts or pilings and the like. A hole 9, 11 through each of the flattened end portions 3 and 5, respectively, is provided to receive a threaded bolt 13. When bolt 13 is inserted through holes 9 and 11, a nut 15 having matching threads engages and is tightened on bolt 13 against flattened end 3 thereby compressing the C-shaped clamp 1. As the nut 15 is tightened or loosened on bolt 13, the bolt head 17 engages flat shoulder 19 formed in the end portion 5 and is prevented from rotating. Alternatively, pin 21 may be inserted through bore 23 provided in end portion 5 and into bore 25 formed in the shaft of bolt 13 thereby preventing rotation of bolt 13 when nut 15 is tightened or loosened on bolt 13. The pin 21 is also used to retain bolt 13 in place when the nut 15 is loose or has been removed. 
     The bolt 13 has a slot 27 formed in the threaded portion of its shaft which extends lengthwise from the end of the bolt 13 to the end of the threaded portion and into the shank portion of the bolt 13. The length of slot 27 must be such that when bolt 13 is inserted through holes 9 and 11 and the nut 15 has been tightened on bolt 13 compressing the C-shaped clamp 1, the slot 27 extends into the open portion 7 between the end portions 3 and 5 of the clamp 1. The width and depth of slot 27 must be such that an elongated, U-shaped key 29 will fit snugly in the slot 27 yet freely slide lengthwise in the slot 27. U-shaped key 29 is formed from metal, such as spring steel, or other suitable material which has a much greater tensile strength than the material that the C-shaped clamp 1 is made from. 
     To assemble the battery terminal clamp 10, the nut 15 is positioned adjacent the outside surface of flattened end portion 3, aligned with hole 9. U-shaped key 29 is inserted lengthwise through the nut 15 and hole 9 such that the legs 33, 31 of the &#34;U&#34; extend radially outwardly from the centerline of the hole 9 and the bore of the nut 15, respectively. One leg 31 is on the outside of the C-shaped clamp adjacent the outwardly facing side of the nut 15 and the other leg 33 is in the open portion 7 of the C-shaped clamp adjacent the inwardly facing side of end portion 3. The bolt 13 is then inserted through hole 11 in end portion 5 of the C-shaped clamp 1 and rotated to align the slot 27 with the key 29. The bolt 13 is then inserted through hole 9 in end portion 3, the key 29 slidingly engaging slot 27. The bolt 13 is further rotated to align a flat portion of bolt head 17 with shoulder 19 or to align bore 25 in the bolt 13 shank with bore 23 in end portion 5 and engaged with nut 15. The nut 15 is then tightened on bolt 13 drawing bolt 13 fully through the end portions 3 and 5 and bolt head 17 into engagement with shoulder 19 or allowing pin 21 to be inserted through bore 23 into bore 25 and thus prevent rotation of bolt 13 as the nut 15 is further tightened or loosened on bolt 13. Further tightening of the nut 15 on bolt 13 will urge nut 15 against the outside wall of flattened end portion 3 compressing the C-shaped clamp 1. Loosening of the nut 15 on bolt 13 urges nut 15 against leg 31 of U-shaped key 29 sliding key 29 in slot 27 and bringing leg 33 of key 29 into contact with the inside wall of flattened end portion 3. Further loosening of the nut 15 on bolt 13 urges the end portion 3 outwardly thereby expanding the C-shaped clamp 1. Preferably, the U-shaped key 29 is oriented in the plane of the C-shaped clamp 1 such that the legs 31, 33 engage the end of the elongated end portion 3 thereby requiring less force to expand the C-shaped clamp 1 as shown in FIG. 2c. 
     Referring now also to FIGS. 3 and 4, a partial view of a storage battery 30 with the self-expandable battery terminal clamp 10 installed on a battery terminal or post 35 is shown. Nut 15 is shown tightened against flattened end portion 3 with the C-shaped clamp 1 compressed tightly around battery post 35 and held securely in position and providing electrical connection between the battery 30 and the cable 39 attached to battery terminal clamp 10. U-shaped key 29 is shown in its installed position in slot 27 with one leg 33 projecting into the clamp open portion 7 adjacent the inside wall of end portion 3 and the other leg 31 adjacent the outwardly facing side of the nut 15. The bolt head 17 is engaged with shoulder 19 to prevent rotation of the bolt 13 whenever the nut 15 is loosened or tightened on bolt 13. Connector 37 is a metal coupling means either molded with or otherwise physically and electrically attached to C-shaped clamp 1 to facilitate connecting battery cable 39 to the battery terminal clamp 10. 
     Another feature of the preferred embodiment is shield 41 which surrounds and encloses battery post 35 and battery terminal clamp 10 to prevent personal injury due to sparking or arcing when the battery terminal clamp 10 is installed on or removed from battery post 35 or resulting from personal contact with any battery acid residue which may be present at the battery post 35. Shield 41 is preferably attached to battery terminal clamp 10 at points 45 as an integral part, but may be installed on the battery 30 separately. Opening 43 in the shield 41 sidewall adjacent the nut 15 is provided to allow the use of a socket or wrench (not shown) to tighten or loosen the nut 15 to allow installation or removal of the battery terminal clamp 10. The shield 41 may be fabricated from sheet metal or plastic or other suitable material. 
     Although the present invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred embodiment has been by way of example and that numerous changes in the details of construction and the combination and arrangements of elements may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.