The present invention relates to power tools, and more particularly to impact tools.
Impact tools or wrenches are typically used for imparting a striking rotational force, or intermittent applications of torque, to a workpiece. For example, impact wrenches are typically used to loosen or remove stuck fasteners (e.g., an automobile lug nut on an axle stud) that are otherwise not removable or very difficult to remove using hand tools.
The invention provides, in one aspect, an impact tool comprising a housing, a motor having an output shaft defining a first axis, a drive shaft rotatably supported by the housing about a second axis oriented substantially normal to the first axis, and an impact mechanism coupled between the motor and the drive shaft and operable to impart a striking rotational force to the drive shaft. The impact mechanism includes an anvil rotatably supported by the housing and coupled to the drive shaft and a hammer coupled to the motor to receive torque from the motor and impart the striking rotational force to the anvil. The impact tool further comprises a ratcheting mechanism operable to prevent rotation of the drive shaft in a selected direction relative to the housing. The ratcheting mechanism includes first and second pawls movably coupled to one of the drive shaft and the housing and ratchet teeth defined on the other of the drive shaft and the housing with which the first and second pawls are engageable.
The invention provides, in another aspect, an impact tool comprising a housing, a motor having an output shaft defining a first axis, a drive shaft rotatably supported by the housing about a second axis oriented substantially normal to the first axis, a gear coupled for co-rotation with the drive shaft, an impact mechanism coupled between the motor and the drive shaft and operable to impart a striking rotational force to the drive shaft, the impact mechanism including, an anvil rotatably supported by the housing and coupled to the drive shaft, the anvil including a pinion engaged with the drive shaft gear, a hammer coupled to the motor to receive torque from the motor and impart the striking rotational force to the anvil, and a spring washer exerting a preload force on the pinion to maintain the pinion meshed with the drive shaft gear.
Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
With reference to
With reference to
With reference to
With continued reference to
The drive shaft 22 includes parallel flats 87 (
With reference to
With reference to
The locking mechanism 106 also includes multiple followers 118 positioned between the cam member 110 and the housing 14. In the illustrated embodiment of the impact tool 10, the locking mechanism 106 includes five followers 118 corresponding with five cam lobes 122 on the cam member 110. Alternatively, the locking mechanism 106 may include a different number of followers 118 and cam lobes 122. With reference to
With reference to
In operation of the impact tool 10, the motor support portion 38 is grasped by the user of the tool 10 during operation. During operation, the motor rotates the drive shaft 22, through the transmission 34, the impact mechanism 38, and the gear train 66, in response to actuation of the trigger switch. The hammer 58 initially co-rotates with the transmission output shaft 50 and upon the first impact between the respective lugs 78, 82 of the anvil 62 and hammer 58, the anvil 62 and the drive shaft 22 are rotated at least an incremental amount provided the reaction torque on the drive shaft 22 is less than a predetermined amount that would otherwise cause the drive shaft 22 to seize. However, should the reaction torque on the drive shaft 22 exceed the predetermined amount, the drive shaft 22 and anvil 62 would seize, causing the hammer 58 to momentarily cease rotation relative to the housing 14 due to the inter-engagement of the respective lugs 78, 82 on the anvil 62 and hammer 58. The transmission output shaft 50, however, continues to be rotated by the motor. Continued relative rotation between the hammer 58 and the transmission output shaft 50 causes the hammer 58 to displace axially away from the anvil 62 against the bias of the spring 98 in accordance with the geometry of the cam grooves 90, 94 within the respective transmission output shaft 50 and the hammer 58.
As the hammer 58 is axially displaced relative to the transmission output shaft 50, the hammer lugs 82 are also displaced relative to the anvil 62 until the hammer lugs 82 are clear of the anvil lugs 78. At this moment, the compressed spring 98 rebounds, thereby axially displacing the hammer 58 toward the anvil 62 and rotationally accelerating the hammer 58 relative to the transmission output shaft 50 as the balls move within the pairs of cam grooves 90, 94 back toward their pre-impact position. The hammer 58 reaches a peak rotational speed, then the next impact occurs between the hammer 58 and the anvil 62. In this manner, a fastener may be driven by a tool bit, socket, and/or driver bit attached to the drive shaft 22 relative to a workpiece in incremental amounts until the fastener is sufficiently tight or loosened relative to the workpiece.
Should the user of the impact tool 10 decide to use the tool 10 as a non-powered torque wrench to apply additional torque to the fastener to either tighten or loosen the fastener, the user need only to manually rotate the impact tool 10 without activating the motor. The resultant reaction torque supplied by the fastener is applied to the drive shaft 22 as a torque input, causing the cam member 110 to rotate relative to the followers 118. As the cam lobes 122 are increasingly misaligned with the respective followers 118, the cam lobes 122 engage and radially displace the followers 118 toward the ring 130 until the teeth 134, 138 of the followers 118 and the ring 130 become engaged. At this time, further rotation of the drive shaft 22 and the cam member 110 relative to the followers 118 is halted and the cam lobes 122 wedge against the corresponding followers 118. Thereafter, the drive shaft 22 remains seized or fixed relative to the housing 14 during continued manual rotation of the impact tool 10. Particularly, the user of the impact tool 10 may use the motor support portion 38 of the housing 14 as a lever for manually rotating the impact tool 10 relative to the workpiece for further tightening or loosening of the fastener. The locking mechanism 106 is operable to lock the drive shaft 22 relative to the housing 14 in this manner regardless of the direction that the impact tool 10 is rotated.
Should the user of the impact tool 10 decide to switch the tool 10 back to a powered impact driver, the user needs only to activate the motor by actuating the trigger switch, thereby co-rotating the ring gear 86, the drive shaft 22, and the cam member 110. The cam lobes 122 are rotated back into alignment with the followers 118 and the lugs 146 re-engage the followers 118, thereby radially inwardly displacing the followers 118 and re-establishing the clearance between the followers 118 and the ring 130. The drive shaft 22 is then free to rotate relative to the housing 14 to resume usage of the tool 10 as an impact driver.
With reference to
The ratcheting mechanism 214 also includes a switching member 234 operable to move the first pair of pawls 218 from the engaged position to the disengaged position while simultaneously moving the second pair of pawls 222 from the disengaged position to the engaged position, thereby toggling the ratcheting mechanism 214 from the first configuration to the second configuration. Likewise, the switching member 234 is operable to move the first pair of pawls 218 from the disengaged position to the engaged position while simultaneously moving the second pair of pawls 222 from the engaged position to the disengaged position, thereby toggling the ratcheting mechanism 214 from the second configuration to the first configuration. In the illustrated embodiment of the ratcheting mechanism 214, the switching member 234 includes axially extending posts 238 on opposite sides of the axis 26a, and the switching member 234 is rotated between two positions coinciding with the first and second configurations of the ratcheting mechanism 214. When in the first configuration of the ratcheting mechanism 214, the posts engage the second pair of pawls 222 to maintain the pawls 222 in the disengaged position. The pawls 218, therefore, are biased inward by the springs 230 into engagement with the ratchet teeth 226 (i.e., the engaged position). Likewise, when in the second configuration of the ratcheting mechanism 214, the posts 238 engage the first pair of pawls 218 to maintain the pawls 218 in the disengaged position. The pawls 222, therefore, are biased inward by the springs 230 into engagement with the ratchet teeth 226 (i.e., the engaged position). Alternatively, the switching member 234 may include different structure for moving the first and second pairs of pawls 218, 222 between their respective engaged and disengaged positions.
With continued reference to
Should the user of the impact tool 10a decide to use the tool 10a as a non-powered torque wrench to apply additional torque to a fastener to tighten the fastener, the user of the impact tool 10a may grasp the motor support portion 38a of the housing 14a as a lever for manually rotating the impact tool 10a relative to the workpiece for further tightening the fastener. Particularly, the user of the impact tool 10a would first rotate the switching member 234 to a position in which the pawls 218 engage the ratchet teeth 226 on the drive shaft 22a, and then rotate the housing 14a (and therefore the pawls 218) in a clockwise direction about the axis 26a (from the frame of reference of
Should the user of the impact tool 10a decide to resume using the tool 10a as a powered impact driver, the user needs only to activate the motor by depressing the trigger switch. The pawls 218 will ratchet over the ratchet teeth 226 in response to the motor rotating the drive shaft 22a in a counter-clockwise direction.
Likewise, should the user of the impact tool 10a decide to use the tool 10a as a non-powered torque wrench to apply additional torque to a fastener to loosen the fastener, the user of the impact tool 10a may grasp the motor support portion 38a of the housing 14a as a lever for manually rotating the impact tool 10a relative to the workpiece for further loosening the fastener. Particularly, the user of the impact tool 10a would first rotate the switching member 234 to a position in which the pawls 222 engage the ratchet teeth 226 on the drive shaft 22a, and then rotate the housing 14a (and therefore the pawls 222) in a counter-clockwise direction about the axis 26a (from the frame of reference of
Should the user of the impact tool 10a decide to resume using the tool 10a as a powered impact driver, the user needs only to activate the motor by depressing the trigger switch. The pawls 222 will ratchet over the ratchet teeth 226 in response to the drive shaft 22a being rotated in a clockwise direction by the motor.
With reference to
Various features of the invention are set forth in the following claims.
This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 14/210,812, filed on Mar. 14, 2014, which claims priority to U.S. Provisional Patent Application No. 61/781,075 filed on Mar. 14, 2013, the entire contents of both of which are incorporated herein by reference.
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Number | Date | Country | |
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Parent | 14210812 | Mar 2014 | US |
Child | 16278818 | US |