Locking mechanism for an articulating oscillating power tool

An oscillating power tool includes a tool mount which can be articulated through a range of positions including less than zero degrees to ninety degrees. The tool mount can accept a variety of accessory tools which move in a reversing angular displacement as well as articulate throughout the range of positions. A locking mechanism is provided that can be manually actuated to prevent articulation or rotation of the articulator to thereby fix the tool mount to a pre-selected orientation.

FIELD

This disclosure relates to the field of power tools, and more particularly to a handheld power tool having an oscillating tool which can be articulated through a range of positions including less than zero degrees to ninety degrees.

BACKGROUND

Oscillating power tools are lightweight, handheld tools configured to oscillate various accessory tools and attachments, such as cutting blades, sanding discs, grinding tools, and many others. The accessory tools and attachments can enable the oscillating power tool to shape and contour workpieces in a many different ways. Previously known oscillating tools, however, are limited in their ability to perform certain tasks in work areas that are difficult to access. These oscillating power tools have fixed tool heads which can limit the number of tasks that can be performed. Oscillating power tools with fixed tool heads can also cause the user to locate the tool in less convenient positions when performing work. Sometimes the position of the power tool necessitated by the nature of the workpiece can be inadequate to effectively complete a task. The user may be forced to either select another tool to complete the task, or resort to non-powered tools, both of which can increase the amount of time to complete a task as well as reduce the amount of time the user can work on the workpiece due to fatigue.

For example, while different types of accessory tools are available to perform cutting, scraping, and sanding operations, the use of such accessory tools is limited in an oscillating power tool where the tool head is fixed with respect to the tool, the tool body or tool handle. The range of uses for these accessory tools, consequently, can be rather narrow, since the output orientation of the oscillating tool head is fixed according to the position of the power tool, the tool body or tool handle. For example, a flush cutting blade accessory for an oscillating power tool can be used to trim or shave thin layers of material from the surface of a workpiece. Because this type of accessory can present a risk that the blade can gouge the surface and possibly ruin the workpiece, orientation of the tool head is important and made more difficult in power tools with fixed tool heads. What is needed, therefore, is a handheld articulating oscillating power tool that provides access to areas that are otherwise inaccessible or difficult to access.

SUMMARY

In accordance with one embodiment of the disclosure, there is provided an articulating power tool including a housing and a motor located in the housing. An actuator is operatively coupled to the drive shaft of the motor and configured to convert the rotation of the drive shaft to a reversing angular displacement. A tool holder is coupled to the actuator and configured to move in response to movement of the actuator. An articulator is operatively coupled to the housing and to the tool holder, wherein the articulator is configured to adjust the tool holder through a range of positions. A locking mechanism is provided that is manually operable to lock the articulator to an articulated position. In one aspect, the locking mechanism includes a translatable locking plate and a ball and ramp clamping mechanism that is operable to translate the locking plate between a locking position in which the locking plate bears against a surface of the articulator to prevent further articulation, and a free position in which the locking plate is offset from the articulator surface to permit further articulation. The locking mechanism of this embodiment provides a low friction mechanism that can be easily manually actuated. The locking mechanism does not require lateral translation of the tool mount so that no modifications are required to other components of the tool, such as dust shielding.

In other embodiments, the locking mechanism can comprise a friction plate or spring plate pack with a manually tightened pressure screw that presses the articulator against the friction plate pack to fix the articulator against articulation. An additional actuator may be in the form of an eccentric lever with an eccentric cam element operable to apply pressure to the articulator.

DETAILED DESCRIPTION

FIG. 1illustrates an oscillating power tool10having a generally cylindrically shaped housing12and a tool holder14, or tool head, located at a front end16of the tool10. The tool holder14is adapted to accept a number of different tools or tool accessories, one of which is illustrated as a scraping tool18. The scraping tool18oscillates from side to side or in a reversing angular displacement along the direction20. Other oscillating accessory tools are known and include those having different sizes, types, and functions including those performing cutting, scraping, and sanding operations. The housing12can be constructed of a rigid material such as plastic, metal, or composite materials such as a fiber reinforced polymer. The housing12can include a nose housing (not shown) to cover the front of the tool, the tool head, and related mechanisms.

The housing12includes a handle portion22which can be formed to provide a gripping area for a user. A rear portion24of the housing can include a battery cover which opens and closes to accept replaceable or rechargeable batteries. The cover can also be part of a replaceable rechargeable battery so that the cover stays attached to the rechargeable battery as part of a battery housing. In other embodiment, the tool10can be powered by another energy source such as harvesting from adjacent power tool, vessel (tool box), solar energy, DC, AC, or the like. Housing12includes a power switch26to apply power to or to remove power from a motor (to be described later) to move the tool18in the oscillating direction20. The power switch26can adjust the amount of power provided to the motor to control motor speed and the oscillating speed of the tool18.

The front end16of the tool10includes a drive shaft support28which receives a drive shaft coupled to the motor, an end portion30of which is supported for rotation within the support28. An articulator32includes an articulating support having a first articulation arm34and a second articulation arm36, each having a first end pivotally coupled to the drive shaft support28at an axis of rotation38. A second end of the arms34and36are coupled to the tool holder14by respective bolts40. Each of the bolts40can fix the arms34and36to the tool holder14such that rotation of the tool holder14does not occur at the location of the bolts40. The interface between the arms34and36and the tool holder can, however, be configured to allow rotational movement of the tool holder around an axis42to provide an additional location of tool head adjustment.

As shown inFIG. 2the motor drive shaft52projects from the housing12and is generally aligned along a longitudinal axis of the housing12. An eccentric drive shaft56is mounted to the end of the drive shaft50and includes a central portion to which an eccentric drive bearing60is mounted. The eccentric bearing60operates as an “eccentric” to convert the rotational motion of the drive shaft52to a linear motion. A link66is operatively coupled to the eccentric drive bearing60and to a tool mount67located within the tool holder14that is configured to engage a bolt70(FIG. 3) to fasten the tool18in a fixed position with respect to the tool mount67. Bearings71, operatively coupled to the tool mount67, provide for rotational movement of the tool mount67within the tool holder14. The tool mount67engages an end74of the link66.

As further illustrated inFIG. 2, the link66is operatively coupled to and actuated by the eccentric bearing60to move responsively to the rotation of the drive shaft52. The end74therefore actuates the tool18bi-directionally in the direction20ofFIG. 1. In one embodiment of the disclosure, the link includes a first branch76and a second branch78coupled at one end to the connecting end74and at an opposite end to the eccentric bearing60.

FIG. 3provides a view of the oscillating power tool10in which the articulating arms are located at approximately ninety (90) degrees with respect to the longitudinal axis of the tool. While articulation is illustrated at less than zero degrees and ninety degrees, the embodiments are not limited to this range of motion. Articulation at greater than ninety degrees is also possible. In another embodiment, articulation at less than zero degree is possible (from the zero degree position).

As shown inFIG. 1, the first articulation arm34and the second articulation arm36are pivotably coupled to a support28to move in an arc about the axis38. Because the arms34and36rotate about the axis38and the link66is coupled to the tool head14, the branches76and78of the link66also generally rotate about the axis38. Consequently, side-to-side movement of the branches76and78(and thus the tool holder14) occurs at a predefined pivot axis due to the location of the pivot axis38, the location of the arms34and36, and the location of the drive bearing60.FIG. 2is a partial sectional perspective view of a portion of the power tool10ofFIG. 1along a line2-2with the housing for the tool holder14removed to illustrate the connection of the link66to the tool mount67.FIG. 3additionally illustrates the rotational axis38and its location through the pivot points of the arms34and36, and through the pivot point of the link66.

In the embodiment ofFIGS. 1-3, the articulated position of the tool mount14is fixed by tightening the bolt40. When the bolt40is loosened, the arms34,36of the articulator32and the branches76,78of the link66act as an articulating linkage as the tool mount14is moved between the parallel position shown inFIG. 1and the perpendicular position shown inFIG. 3. Once the operator has positioned the tool mount and tool18at the desired orientation, the bolt40can be manually tightened to hold the articulating linkage fixed.

In another embodiment, the tool10is provided with a locking mechanism100, as shown inFIGS. 4-7. The mechanism utilizes a ball-in-ramp clamping mechanism to fix the tool mount14′ at a user selected angle relative to the longitudinal axis of the tool. The locking mechanism100incorporates modifications to the tool mount14′ to include a barrel element102that encloses the eccentric drive shaft56, eccentric drive bearing60and link66, and their associated components, as shown inFIGS. 4-5. The barrel element102is integrated with the tool mount14′ by an extension103in lieu of the arms34,36of the embodiment ofFIG. 1.

The tool mount barrel element102includes a pivot surface105at an outboard end of the barrel and a clamping surface106at an inboard end. The clamping surface106may be provided with some form of surface treatment for enhanced engagement or frictional engagement, such as radial splines in one specific embodiment. The clamping surface106is configured for a tight anti-rotation engagement with an opposing clamping surface as described in more detail herein.

The locking mechanism100further includes a locking mechanism housing110that is concentrically disposed around the barrel portion102of the tool mount. The locking mechanism housing110is fixed to the tool housing12in a suitable manner, including being integrally formed with the tool housing. The mechanism housing110defines a cylindrical chamber111that receives the barrel portion102and that is open at one side for passage of the extension103, as shown inFIG. 4. The mechanism housing110includes an inner pivot surface112for sliding rotational contact with the pivot surface103of the tool mount barrel element102. The mechanism housing further includes a cylindrical portion114extending along the longitudinal axis of the mechanism housing and perpendicular to the tool housing12. The cylindrical portion receives the clamping mechanism120and opens to the chamber111so that the clamping mechanism can engage the tool mount barrel portion to fix the articulated position of the tool mount.

In one aspect, the locking mechanism100further includes a clamping mechanism120, and more particularly a “ball-in-ramp” clamping mechanism. The clamping mechanism includes a locking plate122that includes a clamping surface123configured and arranged for anti-rotation clamping engagement with the clamping surface106of the tool mount barrel portion102. As seen in more detail inFIG. 6, the locking plate122includes a number of annular channels126defined in a facing surface127on the opposite face from the clamping surface123. The channels126are configured to receive a corresponding ball145(FIG. 4), which may be similar to a ball bearing, or other suitable movable member such as a roller. The channels are configured to become progressively more shallow from end126ato end126bso that as each ball145moves in the clockwise direction relative to the facing surface127it translates away from the facing surface.

The locking plate122is configured to interface with an input plate130, shown in detail inFIG. 7. The input plate130includes a like number of channels132defined in its own facing surface133, with each channel132likewise configured to receive a ball145. The channels132also become progressively more shallow from end132ato end132bso that clockwise rotation of the input plate130causes each ball145to move toward the shallow end132bof each channel which then causes the balls145to translate away from the facing surface133toward the locking plate122. In other words, as shown inFIG. 5, rotation of the input plate130in the direction of arrow R causes translation of the locking plate122in the direction of the arrow T toward the clamping surface106of the tool mount barrel element102. This transverse or perpendicular movement causes the clamping surface123of the locking plate122to bear against the clamping surface106to lock the barrel element102against rotation. The locking plate122may be provided with anti-rotation lugs128that ride within corresponding grooves (not shown) defined in the locking mechanism housing110to hold the locking plate against rotation while allowing it to translate toward and away from the barrel element102.

The input plate130includes a transversely projecting hub135that extends through the cylindrical housing portion114. A roller bearing assembly150may be mounted within the cylindrical housing portion114in contact with the hub135of the input plate130to facilitate rotation of the input plate relative to the locking mechanism housing110. The roller bearing assembly may be fixed within the housing in a conventional manner, such as with a snap-ring. The roller bearing assembly150may be separate from the input plate130or may be integrated with the input plate or hub135. The outboard end138of the hub135may be configured to mate with a tool, knob, handle, or other manually operable component capable of rotating the input plate130. In one embodiment, the end18may be configured to mate with a tool used to mount the tool18to the tool mount14′. The clamping mechanism120may include a centering pin145that extends through concentric bores in the input plate130, locking plate122and tool mount barrel element102, as shown inFIG. 4. The centering element also operates as an axle for rotation of the clamping mechanism components within the cylindrical housing portion114of the locking mechanism housing110.

The locking mechanism100is easily operated to lock the articulating tool mount14′ at a user-selected orientation. Once the tool mount and tool are situated in the desired orientation, the hub135of the input plate130is manually rotated in the clockwise direction, as indicated by the arrow R inFIG. 5. This rotation moves the ramps132of the input plate130in the clockwise direction so that the balls145trapped between the locking plate122and input plate130are gradually forced to the shallow ends132band126b, respectively, of the channels132and126. Since the transverse or translational position of the input plate130is fixed, the act of forcing the balls145into the shallow ends of the respective channels means that the balls145move away from the fixed facing surface133, toward the facing surface127of the locking plate, which in turn transmits force against the locking plate to cause it to translate transversely toward the clamping surface106of the tool mount barrel element102. Since the barrel element102is translationally fixed, pressure from the locking plate locks the respective clamping surfaces106and123together to prevent rotation of the barrel element and tool mount14′.

Rotation of the input plate hub135in the counterclockwise gradually moves the deeper end132aof the input plate to the balls145and continued counterclockwise eventually positions the plates and balls relative to each other so that the balls145are all situated in the deeper ends of both sets of channels126,132. In this position the clamping mechanism is no longer generating a clamping force against the tool mount barrel element102, so the tool mount14′ is free to be articulated to another position. A return spring (not shown) may be incorporated between the two clamping surfaces106and123, concentrically disposed about the centering pin140. The spring thus ensures disengagement of the two clamping surfaces106,123once the clamping pressure has been removed. It is contemplated that the slope of the ramps132can be customized to the user's desire. For instance, a collection of input plates130may be provided with different ramp configurations.

Other locking mechanism may be provided for locking the articulator32at a user-selected orientation. One such locking mechanism170is shown inFIGS. 8-9. The locking mechanism170engages a modified barrel element102″ of a tool holder14″ between a pressure screw174and a friction disc stack177. The friction disc stack177is disposed between a housing172, which is configured similar to the housing110, and a locking surface105″ of the barrel element102″. The pressure screw174is threaded through a wall of the housing172to bear against a contact surface106″ of the barrel element. A knob175may be provided to facilitate rotation of the pressure screw. As the screw is rotated the screw pushes the barrel element102″ into the friction disc stack177which is then pressed into the housing172. With enough pressure the friction plate stack fixes the locking surface105″ relative to the housing to thereby hold the articulator, and ultimately the tool holder14″ in the user-selected position.

Another locking mechanism190shown inFIG. 10includes a housing192similar to the housing110. The tool holder14is modified to include a locking surface196that is acted on by a locking plate194. The surface196and plate196may be provided with anti-rotation or friction-enhancing features, such as radial splines. The locking plate194is pressed against the surface196by balls198moving between the housing192and ramp surfaces197on the locking plate. The balls198may be mounted within a carrier199that can be moved longitudinally to move the balls up the ramp surfaces197. This movement of the balls generates a transverse force between the locking plate194and the locking surface196to fix the tool holder14at its articulated orientation. A locator pin193may be provided in the housing192to act as a pivot axis for the tool holder14and to prevent disengagement of the tool holder from the locking mechanism190when no locking pressure is being applied.

The locking mechanism210shown inFIG. 11operates on a similar principle to the mechanism190. A ball217is disposed between a tapered surface214of the housing212and an engagement surface215of the tool holder14. Translating the ball217longitudinally toward the tool housing advances the ball along the tapered surface214to thereby exert a transverse force against the engagement surface215, to thereby fix the tool holder against rotation. The ball217may mounted within a carrier that is movably mounted to the housing212.

The locking mechanism220shown inFIGS. 12-13employs an eccentric lever222with an eccentric cam hub224. Pivoting the lever22causes the cam hub224to pivot eccentrically on the outside surface of the housing221. A pressure pin226pivotably mounted to the eccentric cam hub includes a flange227that presses against a contact surface228of the tool holder14. A spring pack229may be provided to push the pressure pin226away from the tool holder as the eccentric lever is moved to its unlocked position.

A locking mechanism240shown inFIG. 14includes a spring pack242that bears against a pressure plate248, which in turn presses against the barrel element102of the tool holder14to prevent further articulation of the tool holder. A locking screw244is threaded into the barrel element102to compress the spring pack242to apply locking pressure as described above. The head of the locking screw244may be provided with a tool-receiving recess configured to receive an Allen wrench or similar tool.

A locking mechanism300is shown inFIGS. 15-18that is configured to apply a preloaded clamping load to the tool holder14. The clamping load is created during the factory assembly process resulting in a more compact assembly. For the locking mechanism300the barrel element302is similar to the barrel element102with the additional feature of a pressure or friction surface304, an array of teeth303and a pivot opening305. The barrel element302is constrained between a pair of thrust bearings312and340. The thrust bearing312includes a pivot hub313that is rotatably mounted within the pivot opening305of the barrel element302. The thrust bearing340is mounted between a housing306and the pressure surface304.

The thrust bearing312includes an angled surface315extending into a bore307of the housing306. The bore supports a Belleville spring322that is captured within the bore by a locking disc325and a threaded adjustment disc327. An array of rolling elements320are disposed between the angled surface315and the Belleville spring322to transmit thrust from the spring to the thrust bearing312. The amount of thrust can be adjusted by adjusting the threaded adjustment disc327. The angled surface315of the thrust bearing allows rotation of the bearing under load while also ensuring that there is no translation of the tool holder14in the X, Y and Z axes. The angled surface315of the thrust bearing312allows the user to easily rotate the tool holder to a desired angular orientation with minimal effort while the clamping load is never released. The Belleville spring322also ensures that the clamping load maintains consistent even as the tool wears.

The second thrust bearing340interacts with a pivot mechanism that allows the user to adjust the angular orientation of the tool holder14. The mechanism includes a pivot lever330that is pivotably mounted to the housing306by a pivot pin342passing through pivot arms338. As shown inFIG. 18pivot lever330includes a pressure pad332that can be depressed by the user. The pivot lever further includes an engagement arm335with teeth336configured for meshed engagement with the teeth303on the barrel element302, as best seen inFIG. 17. The pivot lever can be spring biased so that the teeth336are engaged to the teeth303. The user can adjust the angle of the tool head by pressing the pad332to pivot the engagement arm335about the pivot arms338. The teeth336disengage the teeth303on the barrel element, thereby allow the barrel element302of the tool holder14to be pivoted until the tool holder is at a desired angle. The pressure pad can then be released so that the teeth336fall into meshed engagement with the teeth on the barrel element, thereby holding the tool holder in the desired orientation.