Patent Application
20070266837
The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:
Referring to
With continued reference to
In the preferred embodiment shown in
The clamp assembly 106 preferably includes a body 108, a bolt assembly 110 located within the body 108, a planet gear assembly 102 including a plurality of planet gears 112 and a sun gear 114 contained within the body 108 (three planet gears are provided in the embodiments illustrated) and a cap 118. In the preferred embodiment, the outer surface of the body 108 includes a groove or channel 120 shaped to provide engagement between the body 108 and the cap 118 via pins 122 inserted in apertures 124 in the cap 118 so that the pins 122 slide in the channel 120 and retain the cap 118 to the body 108 while allowing the cap 118 to rotate with respect to the body 108. However, those of ordinary skill in the art will appreciate that the cap 118 may be secured to the body 108 in other ways without departing from the scope and spirit of the present invention. However, the securing method used should not unduly interfere with rotation of the cap 118 on the body 108, although some interference may be desirable, such as frictional interference or the like, for preventing unwanted movement of the cap 118.
The bolt assembly 110 is preferably seated in the body 108 and includes a spindle bolt 124 having threads 126. The spindle bolt 124 preferably extends through an aperture 128 formed in the bottom 130 of the body 108 for coupling the blade clamp assembly 100 to the spindle 14 of the power tool (e.g., power tool 10 shown in
In a preferred embodiment, the power tool 10 may include a spindle locking mechanism (not shown) that, when depressed by the user, engages a hole formed in the motor output drive shaft or spindle 14 of the power tool 10 to lock the spindle 14 in place. The spindle 14 is then prevented from spinning as the cap 118 is rotated by the user for tightening or loosening the clamp assembly 100, thereby clamping the accessory 16 against the flange 18 of the spindle 14 or releasing the accessory from the flange 18.
As shown in
In a preferred embodiment, the planetary gear system 102 further includes a ring gear 142 formed on an inner side surface 144 of the body 108. The planet gears 112 of the planet gear assembly 102 orbit about the sun gear 114 within the ring gear 142. In a preferred embodiment, shown in
The clutch plate 150 preferably includes a plurality of biasing arms 152 that are configured and dimensioned to be positioned in a recess 154, located between the plurality of engagement members 156. As the cap 118 is rotated by the user, the biasing arms 152 abut the sloped surfaces 158 of the engagement members 156. This causes the clutch plate 150 to rotate, turning the sun gear 114, which turns the planet gears 112 and rotates the carrier 146, which in turn rotates the spindle bolt 124 for threading the spindle bolt 124 into the spindle 14.
In a preferred embodiment, the gear teeth of the planet gears 112 are enmeshed between the gear teeth of the sun gear 114 and the gear teeth of the ring gear 142. Preferably, the planet gears 112 are rotationally connected to the pins 148 so that the planet gears 112 rotate while orbiting between the sun gear 114 and the ring gear 142 when the cap 122 is rotated by the user. The planet gears 112 rotate and orbit, causing the bolt assembly 110 to rotate in the same direction as the cap 118, though at a slower rate. In this manner, the spindle bolt 124, which is threaded to the spindle 14, rotates when the cap 118 is rotated, compressing accessory 16 between the washer 104 and the spindle flange 18 thereby securing the accessory 16 to the spindle 14. Alternately, when the cap 118 is rotated in the opposing direction, the bolt assembly 110 also rotates in the opposing direction, loosening the spindle bolt 124 from the spindle and unclamping the accessory 16 so that the accessory 16 may be released from the spindle 14.
Preferably, the size and pitch of the gear teeth of the planet gears 112, the sun gear 114 and the ring gear 142 are selected along with the respective diameters of the cap 118, the planet gears 112 and the body ring gear 142 to provide the desired torque multiplication. However, it will be appreciated by those of skill in the art that the present invention need not be limited to the configuration specifically disclosed herein. For example, it is contemplated that additional layers of planet gears may be provided without departing from the scope and spirit of the present invention.
The planetary design of the present invention is capable of providing a large torque advantage compared to a conventional hand-tightened spindle bolt since the torque applied to the spindle bolt 124 by hand-tightening the cap 118 may be multiplied many times over that which is typically applied by a user's hand. Those of ordinary skill in the art will appreciate that the torque magnification factor of the present invention will depend upon the size of the parts, pitch diameters chosen for the parts, and the like. In the case of a conventional power tool, such as power tool 10, for example, parts may be chosen for enabling a person of ordinary physical strength to hand-tighten the accessory clamp assembly 100 sufficiently to provide adequate axial force for retaining the accessory 16 against the flange 18 of the spindle 14. This may be desirable because the human hand is not typically capable of applying the needed torque for sufficiently tightening a conventional hex-head-type blade clamp assembly without the use of hand tools, such as wrenches, or the like, to provide the necessary additional mechanical advantage.
In embodiments of the present invention, the cap 118 further includes an extensible lever 160 for providing additional mechanical advantage for tightening the accessory clamp assembly 100 onto the spindle 14. In the embodiment illustrated in
In accordance with an exemplary embodiment of the present invention, to install an accessory 16 onto the spindle 14 of the power tool 10, the accessory 16 is first placed on the spindle 14 against the spindle flange 18. The washer 104 is then placed on the spindle 14 against the accessory 16 with ridges or keys 136 facing outward away from the accessory 16. The spindle bolt 124 of the clamp assembly 112 is next threaded into the threaded hole 22 of the spindle 14 and the clamp assembly 112 is spun on until the spindle bolt 124 is hand tight. As the spinning body 108 of the clamp assembly 112 advances against the washer 104 and the keys 136 and 140 of the washer 104 and the body 108 mesh, the body 108 of the clamp assembly 112 stops rotating. The spindle lock (not shown) of the power tool is then engaged to prevent rotation of the spindle 14. Next, the extensible lever 160 is manually extended and used to rotate the cap 118, driving the cap 118 about the center axis of the spindle bolt 124. As the cap 118 is rotated, the torque from the cap 118 is transmitted through the sloped surfaces 158 of the engagement members 156 and the biasing arms 152 to the clutch plate 150 and the planetary gear system 102. The planetary gear system 102 multiplies the torque applied to the lever 160, causing the thread of the spindle bolt 124 to advance into the threaded hole 22 formed in the spindle 14 and forcing the body 108 against the washer 104 which is, in turn, forced against accessory 16 clamping the accessory 16 between the washer 104 and the flange 18 of the spindle 16. As the torque applied reaches a certain pre-set level, the biasing arms 152 deflect away from the sloped surfaces 158 of the engagement members 156, disengaging the cap 118 from the rest of the of the clamp assembly, allowing the cap 118 to rotate relative to the clutch plate 150, effectively stopping the transmission of torque from the cap to the rest of the clamp assembly. This clutching limits the torque to a pre-set value to prevent over tightening of the accessory clamp assembly 100 and produces a ratcheting noise providing the user with audible feedback that the clamping assembly is properly tightened. After the accessory clamp assembly 100 is tightened, the extensible lever 160 is slid back into the cap 118. In an another preferred embodiment, the lever 160 may be spring biased to automatically retract back into the cap 118 once the user is finished tightening the accessory clamp assembly 100. Removal of the accessory clamp assembly 100 for replacing accessory 16 is accomplished by reversing this process.
Turning to
In this preferred embodiment, cap 118 preferably includes a fixed handle 202 that extends from the cap 118 along with surface groves 204 to assist the user in rotating the clamp assembly 200. A wear ring 220 is also preferably included to assist in holding the clamp assembly 200 together.
In addition, accessory clamp assembly 200 preferably includes a loading system that provides an axial loading force to keep the planetary gear system 102 engaged at all times during the rotation of the accessory clamp assembly 200, during the tightening and loosening processes. In a preferred embodiment, the loading system includes a biasing element 210 and biasing arms 152 having a cam profile 224 to engage at least two of the engagement members 156 on cap 118.
The biasing element 210 preferably is a cone washer and provides axial loading by providing a downward biasing force against the body 108 and an upward biasing force against the bolt assembly 110. The axial loading prevents the cap 118 from rotating with the body 108 by creating a frictional force between the biasing element 210 and the body 108 preventing the body 108 from rotating when the user rotates the accessory clamp assembly 200 to either install the assembly 200 or remove the assembly 200. By preventing the cap 118 and the body 108 from rotating together, the planetary gear system 102 remains engaged. In other preferred embodiments, the biasing element 210 may be a spring washer, a flat washer, a wavy washer or a composite washer and the biasing element 210 may be placed in other locations within accessory clamp assembly 200.
In addition, in a preferred embodiment, during the installation process, when the accessory clamp assembly 200 is tightened such that it abuts the accessory 16, continued tightening of the accessory clamp assembly 200 will result in compression of the biasing element 210. With the biasing element 210 full compressed, it will no longer provide axial loading or a frictional force, however, the accessory 16 abutting against the body 108 will provide the requisite frictional force to prevent the body 108 from rotating with the cap 118.
The cam profile 224 is configured and dimensioned so that the biasing arm 152 is always slightly deflected by an engagement member 156 creating axial loading. This axial loading is transmitted to the body 108 to assist in preventing the body 108 from rotating with the cap 118 when the user rotates the accessory clamp assembly 200 to either install the assembly 200 or remove the assembly 200. Again, by preventing the cap 118 and the body 108 from rotating together, the planetary gear system 102 remains engaged.
It is believed that the present invention and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof.
