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  Power tool with spindle lockUSPTO Application #: 20080014844Title: Power tool with spindle lock Abstract: A spindle lock equipped hand-held power tool, such as a grinder or circular saw, includes a housing assembly, a motor including a rotating armature shaft, a spindle carried externally of the housing adapted for selectively affixing and releasing a rotating cutting tool and a drive train which drivingly interconnects the motor armature shaft and spindle for the application of torque to the tool upon electrical energization of the motor. A lock member carried in the housing is selectively displaceable along a fixed axis between a locked position wherein it engages a rotating element of the drive train to prevent rotation of the spindle, and a released position. A spring continuously urges the lock member toward the released position. A manually operable lever selectively displaces the lock member between the released and locked positions. (end of abstract) Agent: J. Gordon Lewis - Bloomfield Hills, MI, US Inventor: James Matthew Pontieri USPTO Applicaton #: 20080014844 - Class: 451359 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080014844. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATION [0001]The present application claims the benefit of U.S. Provisional Application No. U.S. Ser. No. 60/831,436, entitled "POWER TOOL SPINDLE LOCK" filed 17 Jul. 2006. TECHNICAL FIELD [0002]The present invention relates generally to hand-held power tools, and, more particularly, to such tools which include a driven spindle configured for drivingly engaging a sacrificial cutting or forming accessory. BACKGROUND OF THE INVENTION [0003]Hand-held grinders are common tools that are used for a variety of applications. Typically, a grinder includes a motor that drives a wheel (such as a grinding wheel, wire brush, or cutting disc). Many grinders include a drive shaft from the motor and a gear system coupled to the drive shaft that changes the direction of rotation. Often, the direction of rotation is changed by 90.degree.. Also, many grinders include a lock pin that can be pressed inwardly to lock the drive shaft relative to the housing of the grinder so that a clamping screw can be loosened or tightened to mount the wheel on the grinder or remove the wheel from the grinder. [0004]Hand held grinders are useful because they are portable and, thus, can be taken to the part to be worked, rather than the part having to be moved to a stationary grinder. Such grinders are often useful in working surfaces of large or bulky machines or parts. As such, they are often used in automobile repair, metal fabrication, welding shops, heavy equipment repair, and woodworking. However, previously known hand grinders have not been able to reach many hidden or obstructed work surfaces or have required excessive work or modification to reach many work surfaces. [0005]U.S. Pat. No. 6,386,961 B1 to Cureton discloses a hand-held grinder which includes a motor and a mounting surface coupled to the motor. A housing supports the mounting surface and the motor. A grinding wheel abuts and is secured to the mounting surface, and the grinding wheel extends beyond an end of the housing. A line that is tangential with the grinding wheel distal from the housing, and that is tangential with the end of the housing, may be at an angle of less than about 45.degree. relative to a plane of rotation of the grinding wheel. The grinder may also include a drive shaft coupled to the motor, a driving gear coupled to the drive shaft, and a driven gear engaging the driving gear and fixed to the mounting surface. The driven gear and the mounting surface are part of a unitary member. The housing defines a bottom housing surface that is substantially coplanar with the mounting surface. The housing defines a tapered end. The grinder includes a telescoping feature wherein the housing includes a first member that is movable relative to a second member to change the length of the grinder. The grinder includes a lock pin that is selectively forced into engagement with the drive shaft, thereby preventing rotation of the drive shaft relative to the housing. [0006]In other power tools, such as a circular saw or router, an internal electric motor has a rotating shaft coupled to a cutting tool at an exposed end. These cutting tools are selectively mounted to or removed from the shaft depending upon the work to be performed by the cutting tool. It is a convenience to the operator, if the rotation of the shaft can be inhibited during the mounting or removal of the cutting tool since the mounting or removal of the cutting tool requires rotary motion about an axis concentric with the shaft. Preferably, the mechanism for locking the shaft should also inhibit electrical power from being applied to the electric motor when the rotation of the shaft is inhibited to prevent damage to the motor or causing it to overheat. [0007]Shaft locking mechanisms which include electrical cut-out switches to prevent electrical power from being applied to the motor when the shaft is locked are known in the art. U.S. Pat. No. 2,897,302 to Godfrey et al. discloses a control mechanism for an ON/OFF switch of a router which automatically locks the shaft when the electrical switch is placed in the OFF position and release the shaft when the electrical switch is placed in the ON position. In an alternate arrangement disclosed in U.S. patent application Ser. No. 07/764,239, filed 23 Sep. 1991 to McCurry, a shaft lock mechanism has a first position in which the shaft is locked and a cut-out switch is placed in an open position. The shaft lock mechanism is manually displaceable to a second position in which the shaft is free to rotate and the cut-out switch is placed in a closed position. [0008]U.S. Pat. No. 5,346,342 to Winchester discloses a shaft lock arrangement having a shaft lock slidably mounted in the housing of a power tool. The shaft lock has a keyhole-shaped aperture having a circular portion circumscribing the output shaft of the power tool when the shaft lock is in the RUN position and a rectangular portion, the sides of which straddle flat portions of the output shaft preventing the output shaft preventing the output shaft from rotating when the shaft lock is in the LOCKED position. The shaft lock further has a run detent resiliently engaged by a toggle of a cut-out switch to hold the shaft lock in the RUN position and a lock detent resiliently engaged by the toggle of the cut-out switch to hold the shaft lock in the LOCKED position. The cut-out switch prevents electrical power from being applied to the motor of the power tool when the shaft of the power tool is locked by the shaft lock. [0009]With devices such as hand-held power tools such as power screwdrivers, it is well known that the torque or force which must be applied to a screw can vary substantially as the screw is advanced into, or removed from, anchoring engagement with an associated work piece. In particular, very large forces may be required to ultimately "set" the screw during installation or to initially "break loose" the screw during removal. Difficulties have been encountered in generating these large driving forces, particularly in small hand-held tools where size and weight considerations necessarily limit the available motor horsepower. The problem is further aggravated where a cordless battery tool operation is contemplated. In such a tool it has been found that batteries of sufficient electrical capacity to power a high-torque cordless screw-driver tool are impractical due to inherent size and weight limitations. This is particularly true with respect to light duty power tools which feature compact, lightweight construction. [0010]U.S. Pat. No. 4,804,048 to Porth, Jr. Proposes a solution to the low torque problem by providing a hand-held power tool including a spindle which is adapted to receive and retain tool bits for rotation thereon. A collet ring is retained with a recess on the tool housing for slidable movement along the spindle axis. The collet functions as a selectable spindle locking device whereby the tool may be operated as a manual screwdriver or the like by selectively positioning the collet to rigidly lock the spindle in a fixed relationship to the tool housing. [0011]In manual work, for instance, by attaching various tools by mounting a chuck on the output shaft of a power tool, if the power switch is turned off, the output continues to rotate by inertia of the chuck or tool, and if the power tool is released from the user's hand during this rotation, the tool is still rotating and can pose a risk of injury. It is therefore preferred that the output shaft be stopped immediately when the power switch is turned off. [0012]In a chuck, there is known a chuck with a torque-up function capable of tightening or detaching the tool, only by turning the operation ring by hand, without having to use a chuck handle, but when using such chuck with torque-up function, while the motor source is off, the output shaft of the power tool is free to rotate. If an attempt is made to tighten the chuck by hand, the output shaft also rotates and it cannot be tightened by hand. Hence it is necessary to fix the output shaft by one hand, and the controllability is poor because of hand tightening of the chuck and holding of the tool. Accordingly, it has been proposed that the output shaft of the power tool be locked while the motor power source is off. [0013]U.S. Pat. No. 5,732,805 to Nakamura discloses a lock device of an output shaft which is capable of stopping the output shaft quickly when the output shaft is controlled to stop, and locking to prevent the output shaft from rotating when the output shaft side is stopped against the drive side. The output shaft is formed by connection of the drive shaft and a driven shaft. Play for a predetermined relative angle is formed in a mutual rotating direction, at a junction of connection of the drive shaft and driven shaft. A holding plate is fixed to the driven shaft side confronting the drive shaft in the axial center direction. An annular lock ring forming a lock pawl on the outer circumference is held movably to a concentric position and an eccentric position, at the holding plate side. A lock operation member is provided on the drive shaft confronting the lock ring, for allowing the lock ring to move to the concentric position when the play at the junction of the drive shaft and driven shaft is eliminated by initial rotation or rotation of the drive shaft, and allowing movement to the eccentric position when rotation of the drive shaft is stopped to reestablish a play at the junction by reaction. An internal ring forming a pawl for locking mutual rotation by mutually engaging with the lock pawl on the outer circumference of the lock ring when the lock ring is moved to the eccentric position is formed oppositely on the outer circumference of the lock ring. [0014]The present invention is an improved shaft lock mechanism for a power tool which overcomes many of the shortcomings of prior art approaches. SUMMARY OF THE INVENTION [0015]An object of the present invention is to develop a spindle locking mechanism for a hand-held power tool which employs a manually operable lever which displaces a locking pin between a retracted position which frees the spindle drive to rotate a tool, and a locked position which prevents rotation of the associated tool spindle, for repair or replacement of the tool, or the like. [0016]According to the present invention, a hand-held power tool includes a housing assembly, a motor with a rotating armature shaft disposed within the housing assembly, a spindle carried externally with the housing assembly for relative rotation about a drive axis and a drive train interconnecting the motor armature shaft and spindle for the application of torque therebetween upon electrical energization of the motor. A lock member [0017]FIG. 8, is a broken, cross-sectional view of a further alternative lock member construction including a rotating ball-type cam follower feature; [0018]FIG. 9, is an alternative embodiment of the present invention wherein the spindle-lock feature is adapted for aftermarket applications with a hand-held power tool; [0019]FIG. 10, is another alternative embodiment of the present invention wherein the spindle-lock feature is also adopted for an aftermarket application with a hand-held power tool; [0020]FIG. 11, is a cross-sectional view of an alternative "wrench-type" interconnection between the rotating transmission element and lock member; Continue reading... Full patent description for Power tool with spindle lock Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Power tool with spindle lock patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. 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