Patent Document

BACKGROUND OF THE INVENTION 
     This is a continuation-in-part of Ser. No. 045,781, filed Apr. 30, 1988, now Pat. No. 476,840. This co-pending continuation-in-part Ser. No. 07/045,781 is directed to an improved locking arrangement. My Continuation In Part application filed Aug. 24, 1988, now assigned Ser. No. 07/235,287 is an improvement in the control bar locking assembly. The present Continuation In Part assembly appertains to a unique retainer for use in power driven tool. Patent, No. 4,480,511, is directed to a locking arrangement for retaining sockets on a shank. 
    
    
     DISCUSSION OF THE PRIOR ART 
     The typical power-operated wrench is an impact wrench which utilizes a calibrated rotary hammer to exert torque of a selected value. This is used to drive a socket to tighten or loosen a fastener such as a nut or bolt. Several factors make this application significantly different than that of hand operated tools. First the torque generated is significantly greater than can be generated by a hand tool. Second, the speed of rotation is greater than and is maintained over a longer period of time than a manual tool. Third, when the load is released as when a fastener is completely removed, a mechanical element breaks, or the power tool is accidentally operated without load, the tool may rotate at an unwantedly fast speed. Fourth, the cyclical nature of the forces used to impart rotation creates higher stress peaks. Under these circumstances it is desirable to have a retainer element with a more positive engagement on the socket than can be accomplished using a ball-bearing type retainer, or other retainer with a projecting hemispherical surface. 
     In the prior art impact tools utilize sockets designed specifically for the purpose of being driven by impact wrenches. These sockets differ from standard sockets in the addition to mass and composition of the metals used and by having a parallel walled bore extending through the outer surface to one driven wall. This bore is analogous to the retention recess in many manually driven socket extensions but is uniquely adapted to the conditions of impact or power driven wrench driving. 
     The driving end of the tool in the prior art uses a pin projecting from a retainer element instead of a ball or hemispherical surface. The pin extends farther into the bore of the aforementioned socket and provides a greater surface area to retain the socket. 
     Release of prior art impact tool retention devices is accomplished through the use of an implement inserted in the bore in the socket and depressing the pin against a spring which forces it outward. This has a number of disadvantages. A separate tool is prone to loss, breakage or misuse. There may be delays and inefficiencies in changing sockets because of the need to manipulate the tool. There may be a tendency to misuse tools not intended to be used as pin depressing implements, such as screwdrivers or the like, and other disadvantages. 
     BACKGROUND OF THE INVENTION 
     My invention utilizes a positive locking feature of the control bar and first an extension of spring to urge the control bar into a locking position to force a retaining pin into a locked position. In the prior art arrangement a spring directly forces a pin into a locked position. Conversely in my invention I use a second spring to retract the pin from locked position. I use a control bar to engage the retainer assembly a ball and pin, to force the pin into a positively locked position. In my arrangement my device does not use the same spring to maintain the pin in locked position. My arrangement presents a number of advantages. 
     One advantage is the use of a transverse spring to push the pin through the control bar into the locked position. The axial spring is a larger and less fatigue-prone spring. 
     Another advantage is that the locking motion is generated by the axial spring in a direction perpendicular to the direction of motion of the locking pin. 
     Another advantage is that in the locked position, the pin is held in place by the contact of solid elements rather than by spring pressure of a spring. The solid components are less prone to fatigue than said springs used in prior art devices. 
     Another advantage of my invention is that removal of sockets for changing is simplified. 
     Another advantage of my invention is that it facilitates the placement of sockets on the tool for use or when changing sockets. 
    
    
     These and other objects and advantages of the invention will become more apparent from the specification and the drawings, herein. 
     FIG. 1 is a perspective cut away view of my invention. 
     FIG. 2 is a sectional view of my invention in the locked position. 
     FIG. 3 is a view of my invention in the retracted position. 
     FIG. 4 is a sectional view of prior art power socket wrench retention devices. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a socket locking assembly with a driven portion (11) extension shank (9) and square driving portion (12). The driving portion (12) fits into socket (21) for imparting rotational movement. 
     The shank (9) terminates at a shoulder (27) at the end of the shank (9). A slot or channel (10) is formed in the surface of the shank and extends into one face or wall of the drive portion (11). 
     A control bar (14) which has an outer surface (13) is carried in a controlbar channel 10. A raised portion or spur (16) extends outwardly from the outer edge (13) and fits into a sleeve (15). The sleeve has internal annular engagement elements or flanges. In this embodiment these constitute an inner annular ring (28) and terminal annular ring (29) of the sleeve defining an annular groove (30) between them. This preferred embodiment sleeve does not foreclose the use of other methods of engagement. A first or axial spring (17) urges the sleeve and control bar into the locked position. The forward locked position motion of the sleeve toward the driving end is limited by a circular clip (18) fitted into an annular groove in the shank (9). The clip may also be used to limit radial outward movement of the control bar. Rearward movement of the assembly is limited by a limiting collar (52) which may be a raised annular ridge on the shank (9) or a separate piece which engages the sleeve. In the preferred embodiment the sleeve may be covered with a grip surface pattern such as knurling, or other arrangements making the sleeve easy to grip and retract. 
     FIG. 2 is a sectional view of the preferred embodiment. The socket (21) has a plurality of faces (31) which engage the drive portion (12). Apparent in this view is a transverse bore (19) in which a retainer ball (24 and a retainer pin (74) are carried. The control bar (14) carried in the control bar channel (10) extends forward or toward the distal end (95) (to the left). The outer surface (13) of the control bar which rides under the stop ring (18) engages a wall of the socket (31) when in the locked position. The inner surface (50) of the control bar slides on the floor (60) of the channel (10). The inner surface (50) merges into a bevel (25) which slides over ball (24). It has been found in development that a bevel angle of between approximately 10 and 30 degrees is preferable. For improved clearance and engagement of the socket, the tip of the control bar is also beveled at (51) adjacent to the outer surface (13). 
     Further apparent in this view are the sleeve-control bar engagement shoulders (28) and (29) which flank and engage the outwardly extending spur (16) of the control bar permitting fore and aft retraction and extension against a force through the action of a compressed coil spring (17). As noted in connection with FIG. 1 forward and radially outward motion is limited by the circular clip (18) snapped into groove (96) in the shank although other appropriate structures including the sleeve (15) may be used. 
     The locking or securement of the socket (21) to the driving end (12) is accomplished through the engagement of an outwardly projecting detent or pin (74) with a cylindrical opening (75) in the socket. Typically a socket design for power driven use has a single hole drilled through one wall of the socket. 
     The pin (74) has a cylindrical projecting portion (76) which projects through the transverse bore (19) in the shank and engages in the cylindrical opening (75) of the socket (21) to lock the socket in place when the control bar (14) is in the locked position. 
     With the control bar held in this position by the first or axial, spring (17), a positive lock is maintained by the other surface (13) of the control bar bearing on the socket wall (31) opposite the retainer opening (75), the inner surface (50) of the control bar bearing on the retainer ball (24) which in turn bears on the head (77) of the pin (74). This head is of a larger diameter than the projecting locking portion (76) and provides a bearing surface for the retainer ball (24) on one side and for a second, or transverse retracting or biasing spring (78) which reacts against the inside surface of the head and is sleeved on the pin (74) and bears against an opposing shoulder on the shank within the bore (19) at the outlet end (81) thereof. 
     As shown in FIG. 3, the spring (17) is compressed between the engagement shoulder (28) of the sleeve in the limiting collar (52) and an opposing shoulder (57) of the limiting collar. The limiting collar itself maybe a raised annular ridge of the shank a separate piece carried on the shank or other prosecution. The limiting collar incorporates an outwardly extending shoulder (54) extending from the circumferential surface and engages the rearward end (53) of the sleeve (15) at the rearward most extension of travel. Movement rearward (rightward) to the shoulder (54) retracts the control bar (14). The retainer ball (24) is permitted by movement of the bevel to move transversely outwardly. 
     When the control bar (14) is retracted upward biasing of the retainer ball (24) and pin (74) results from the pressure of the transverse or biasing spring (78) against the lower portion of the head (77). The action of the second, or transverse, spring (78) is the opposite of the action of the transverse spring in the prior art in that my transverse spring unlocks the pin (74) from engagement with the socket while the prior art uses a spring to hold a pin in a locked position. 
     FIG. 4 shows the prior art power wrench socket locking arrangement. In this arrangement the pin (274) is held in place by the outward pressure of the spring (278). This pin (274) engages the bore (275) in the socket (221). In this way the socket is retained from unwanted forward (to the left) motion while in operation. In order to remove the socket (221), an implement (280) must be inserted in the bore (275) to engage the projecting portion of the pin (276). The implement (280) is then forced transversely (upward) against the spring pressure while the socket is simultaneously withdrawn, the implement holding the pin in a retracted position. Whenever the force on the pin against the expansion of the spring is released, the pin returns to the locked position. Whenever the implement (280) is withdrawn, or the socket (221) is completely withdrawn, the pin returns to the locked position. Thus, two hands are typically required to manually remove a socket, one to manipulate the socket (221), the other to manipulate the implement (280 , or extreme dexterity is required to both exert the transverse force on the implement (280), and the longitudinal force on the socket (221), while still holding the power wrench itself. 
     Further, in order to replace the socket, the pin must also be retracted against the transverse spring pressure because the pin (274) is substantially parallel to the rear portion (269) of the socket (221). This may be done by the use of a fingernail, in small diameter power wrenches, but may require the use of an implement particularly against the higher spring pressure in larger diameter wrenches. The pin must be held with the spring compressed as the socket is inserted. My invention permits the retraction and holding of the tool with one hand while the socket can usually be manipulated with the other hand dispensing with the implement. Further, my tool uses positive locking to hold the pin in the extended, or projecting position.

Technology Category: 7