Currently, hand tools utilizing ratchets are well-known. On a basic level, these ratchet tools operate so that rotation or drive in a first direction engages internal components so that the tool operates in the manner a traditional non-ratchet tool would to provide rotational drive to a workpiece such as a screw or a bolt, for instance. When the tool is rotated in a second direction opposite the first direction, the internal components are able to slip or ratchet over each other so that this rotation does not counter-drive the workpiece. Accordingly, a user of the tool can engage the tool with the work piece and maintain the tool engaged thereto while rotating and counter-rotating the tool to drive the workpiece. The user simply rotates the tool in the first direction for a portion of a circular sweep which provides drive, then counter-rotates the tool in the second direction without applying drive, then returns to the first direction to again apply drive force.
As is known, these ratchet tools allow a user to insert the operating or driving end of the tool into a tight space and operate the tool over a short sweep in a quick manner. For instance, a space in an engine compartment of an automobile is tightly packed and arranged. Therefore, access to a bolt may be limited, and a high torque is needed to tighten or loosen the bolt. A wrench used to tighten or loosen the bolt may only be able to rotate a small number of degrees before the path of the wrench brings the wrench into contact or interference with other components mounted in the engine compartment. This means that the tool must be rotated these few degrees many times. It is often awkward and difficult to use a traditional (non-ratcheting) tool in these spaces as such requires making a small turn, and then removing and reengaging the tool with the bolt or other workpiece. Thus, the advantage of a ratcheting tool is that it remains engaged and saves significant time and effort when compared to a traditional, non-ratcheting tool.
A ratcheting tool typically has a ratchet gear, the ratchet gear either cooperating with or being integral with a drive portion for delivering torque drive, and either one or two pawls. The single pawl has two sets of ratchet teeth which are alternately engaged with the ratchet gear. The two pawl device, known as a dual-pawl ratchet, has pawls that are moved into and out of engagement with the ratchet gear and have ratchet teeth that selectively engage with the ratchet gear.
An issue with these ratchet tools is that, once the tool has been counter-rotated, the pawls and their teeth must re-engage with the ratchet gear to provide torque drive. Generally speaking, the pawls are biased into engagement with the ratchet gear. However, in both single and dual-pawl arrangements, the bias member provides bias to the pawl(s) in a single direction. As a result, there is wasted rotational movement in order to dis-engage and re-engage the pawl. In common parlance, one would describe such a wrench as having “play” between a point where the wrench is in a fully engaged, driving position and a point at which the pawl slips or “clicks” over the ratchet gear by a single tooth.
By way of illustration, U.S. Pat. No. 6,691,594, to Chen, discloses a reversible dual-pawl ratchet wrench. When rotated in the drive direction, the engaged pawl is constrained by the wrench head, as well as the ratchet gear. When counter-rotated, the pawl does not immediately disengage so that a tooth of the pawl shifts to an adjacent tooth of the ratchet gear. Instead, the pawl slides along the interior of the wrench head until the pawl moves to a position allowing the pawl to shift radially away from the ratchet gear sufficient to allow the teeth of the gear and pawl to slip or, more precisely, to allow the gear teeth to cam the pawl out of engagement. Until the pawl shifts to such a position, the counter-rotation is wasted movement. When the tool is used in a space that provides little overall rotational sweep, this wasted movement can be significant.
Some ratchet tools provide structures that may limit the rotation of the pawl or pawls. For instance, a pawl may be provided with a spring which biases the pawl into engagement with the gear, and counter-rotation of the gear cams the pawl in a direction that compresses the spring. The pawl itself is positioned against one or more rigid portions formed in the ratchet head, such as a channel. For such devices, the pawl may bind with or grind against the channel so that operation of the tool is rendered difficult at times.
Accordingly, there has been a need for an improved arrangement and assembly for a ratcheting tool.
USPTO Backgrounds
USPTO Backgrounds