Patent Application
20110255927
This invention relates to the design of a multi-functional power tool and its blade. The tool may be operated as either a rotary drill or a reciprocating saw. A compound bevel gear engages one of two gears to produce either of the two desired types of motion. The end user is able to toggle between rotary and reciprocating modes with a manual switch.
Over the course of a typical construction project including but not limited to framing, dry-walling, or custom woodworking it may be necessary to switch between an assortment of power tools, the primary ones being a drill and a saw. It is not always convenient or affordable to keep both of these tools on hand. To many it would be desirable to have a single tool capable of performing both of the required functions. It is thus an object of the present invention to provide a single tool capable of both sawing and drilling modes, and not requiring any attachments or disassembly in order to change between modes.
The applicant is aware of patents regarding reciprocating saw motion adapted from a rotary drill such as U.S. Pat. No. 6,264,211 titled “Reciprocating Saw Attachment for Electric Drill”, issued to Granado on Jul. 24, 2001. This describes an attachment that makes use of bevel gears with an eccentric peg and control arm that produces reciprocating motion from the rotation of the drill. The design includes a collar which permits manual tightening of the chuck. The internal components are typically hardened steel, while the case is a hard plastic. Objectives include the ability to attach to all models of drills, with quick connect and disconnect, and to be near maintenance free.
Applicant is also aware of U.S. Pat. No. 6,820,339 titled “Right Angle Accessory Saw for Use with Electric Drill”, which issued to Albrightson on Apr. 1, 2004, and which describes an accessory for an electric drill which produces reciprocating motion for a saw blade at a right angle to the axis of the drill. The motion is achieved through the use of a cam in the accessory which drives the forward motion of a push rod. The push rod is spring biased towards the cam to complete the cycle of motion. The present invention differs from this design by maintaining the same axis for both rotation and translation in a single compact unit.
The embodiment of the present invention ensures power is delivered through the entire cycle using a Scotch yoke mechanism to produce the reciprocating motion.
U.S. Pat. No. 5,766,293 titled “Drill/Saw Apparatus”, issued to Bourke on May 26, 1998, describes a compact drill attachment which converts rotary motion of the drill to reciprocating saw action. It does so using a set of bevel gears and an eccentric peg, which in turn drives a slotted arm to which &saw blade is attached. The patent seeks to cover a variety of speeds, stroke lengths, stroke speeds, and cutting angles in its design for a cordless drill attachment. A hex key fitting is described to enable easy insertion of a power drill into the apparatus at a variety of locations. Various mechanisms such as a worm gear, rack and pinion, and a counterbalancing flywheel are shown in differing adaptations of the original design.
U.S. Pat. No. 4,972,589 titled “Cutting and Sanding Attachments for a Hand Drill”, issued to Povleski on Nov. 27, 1990, describes an attachment that allows a rotary saw or drum sander to be attached to a cordless drill. The design does not produce reciprocating motion. It has a false trigger, which consists of a connecting rod that allows the trigger on the drill to be operated from a position closer to the saw blade. Changing between drilling, sawing, and sanding requires removal of the attachments. The patent also mentions the need to change gears in order to achieve the correct speeds, which does not appear ideal in terms of minimizing the lag time between mode changes.
The applicant is also aware of U.S. Pat. No. 6,641,467 titled “Power Tool”, issued to Robson and Wadge on Feb. 12, 2004: Applicant is also aware of U.S. Pat. Nos. 6,170,579 and 6,263,980 issued to Wadge. These describe a power tool with a rotary fitting onto which a plurality of adapting tool heads may be attached. These include a rotary drill, a jigsaw, as well as a sander. An attachment must be interchanged to switch from sawing to drilling.
Regarding a single power tool that can drive both a drill bit and an elongated saw blade, applicant is aware of:
U.S. Pat. No. 6,170,579 titled “Power Tool Having Interchangeable Tool Head” issued to Brian Wadge on Jan. 9, 2001 teaches a generic power tool having a motor driving a rotary output shaft. The power tool detachably engages one of a plurality of tool heads including a drill chuck, reciprocating saw, sander head and nibbler tool. The reciprocating saw attachment includes a complex mechanism for converting the rotary input motion to reciprocating linear output motion.
U.S. Pat. No. 6,782,781 titled “Saw Blade For Reciprocating Saw Apparatus” issued to Allan A. Rack on Aug. 31, 2004 discloses a saw blade having a toothed, rounded tip for use with a reciprocating saw. In order to start a cut, the user places the tip of the blade on the material to be cut and holds the reciprocating saw such that the blade forms approximately a 45-degree angle with the material. In this way, the tip of the saw blade cuts a groove into the material and eventually cuts through the material so that the blade can pass through and the primary cutting edge can come into contact with the sheet.
U.S. Pat. No. 2,529,157 titled “Routing Tool” issued to Robert J. Higerd on Nov. 7, 1950 teaches a power tool cutting attachment for use with a router. The router bit is rotated at high speeds and cuts sheet material with a plurality of cutting edges spaced evenly around its circumference.
The present invention combines the two common power tool options of a rotary drill and a reciprocating saw into a single compact device. One can change between the two modes by flipping a switch on the side of the case. A compound bevel gear allows power to be transferred to either a spur gear to drive the drill, or to a larger bevel gear with an eccentric peg to drive a Scotch yoke mechanism for the reciprocating saw. The toggling mechanism contains a shaped slide pin which restricts the tool holder to either rotation in the drill mode or translation in the saw mode. A magnetic sensor is used to detect position of the shaft and stop it in the appropriate location to allow for accurate toggling between modes. The gears are mounted in a hard plastic casing which is fixed to a pistol grip style handle housing a motor and the triggering device. A toothed blade for the tool has a spade drill bit tip that can ream holes as well as cut slots. The blade comprises an elongate body similar to a conventional reciprocating saw blade having cutting teeth angled towards the power tool on its lower surface such that the blade will cut the material on its backward stroke. The blade is provided with power-tool engaging means at one end such that it can be driven in linearly as well as rotationally. At its other end, the cutting tool has the profile of a spade bit for a drill, such that the same tool can be used for drilling a pilot hole and cutting the sheet of material.
In summary the drill saw according to one aspect of the present invention may be characterized as including:
a) a motor,
b) a drive shaft rotationally driven by the motor for rotation of the drive shaft about a corresponding drive axis,
c) a transmission cooperating with the drive shaft to convert the rotation of the drive shaft to a driven output,
d) an output shaft lying on an output axis and cooperating with the transmission for imparting the driven output to the output axis,
wherein the transmission includes:
i) a housing,
ii) a shuttle member having first and second gears mounted thereon, wherein the shuttle member is slidably mounted to the housing for translation between first and second positions,
iii) a rotary motion-to-linearly reciprocating motion converter mounted in the housing and operatively cooperating with the first gear when the shuttle member is in the first position, and wherein when the shuttle member is in the first position the driven output is a first driven output driving the output shaft reciprocatingly and linearly along the output axis,
iv) a rotary motion-to-rotary motion coupler mounted in the housing and operatively cooperating with the second gear when the shuttle member is in the second position, and wherein when the shuttle member is in the second position the driven output is a second driven output driving the output shaft rotationally about the output axis,
e) an actuator for selectively actuating the shuttle member between the first and second positions.
In one embodiment the output shaft includes a groove extending linearly along an outer surface of the output shaft and parallel to output axis. A guide member is slidably mounted in the housing for sliding translation between an engaged position wherein the guide member engages in the groove as the output shaft is driven by the first driven output, and a disengaged position wherein the guide member is disengaged from the groove as the output shaft is driven by the second driven output.
The guide member may be actuated between the engaged and disengaged positions by an actuating linkage extending between the guide member and the actuator and cooperating with the actuator so as to actuate the guide member into the engaged position when the shuttle member is actuated into the first position and so as to actuate the guide member into the disengaged position when the shuttle member is actuated into the second position. For example, the actuating linkage may include a portion of the shuttle member, and in particular where the portion of the shuttle member is a protrusion of the shuttle member, the protrusion driving the guide member upon actuation.
The guide member may be resiliently biased into the groove by a resilient biasing means such as a spring. The guide member may further include a collar through which the output shaft is journalled so as to pass therethrough, in which embodiment the protrusion may then drive the collar so as to drive said guide member against the resilient biasing of the resilient biasing means.
In one embodiment the rotary motion-to-linearly reciprocating motion converter includes a driving wheel having a gear engaging surface which engages with the first gear on shuttle member when the shuttle member is in the first position, and a driving linkage eccentrically mounted at one end of the linkage to the wheel and mounted at its opposite end to the output shaft whereby rotation of the wheel drives the linkage to thereby linearly translate and reciprocate the output shaft along the output axis. For example, the wheel and the linkage may be collectively formed as a scotch yoke rotary-to-linear motion converter.
The rotary motion-to-rotary motion coupler may include a rotary output gear mounted on the output shaft cooperating with the second gear when the shuttle member is in the second position. Advantageously, the rotary output gear and the second gear are substantially parallel and, when the shuttle member is in the second position, are substantially co-planar.
In one preferred embodiment, the first gear is a first bevel gear and the gear engaging surface on the wheel is a second bevel gear, and the wheel is orthogonal to the first gear. For example, the first bevel gear and the second gear may form collectively a compound bevel gear where the first and second gears are parallel and adjacent.
In a further aspect of the present invention, a position sensor is mounted in the housing to sense an instantaneous rotary and linear position of the output shaft. A processor cooperates with the position sensor so that the processor may determine when the groove is aligned with the guide member when the shuttle member is in the first position, and so that the processor may determine when the rotary motion-to-rotary motion coupler are operatively connected when the shuttle member is in the second position.
In yet a further aspect, the drillsaw according to the present invention further includes a flat elongate blade having a chuck engaging end, an opposite distal end and a bottom edge extending therebetween along a lower edge of the blade. An array of cutting teeth are formed or mounted along the bottom edge. A drill bit, for example a spade drill bit is formed or mounted at the distal end. The chuck-engaging end is adapted for mounting the blade to the output shaft along the output axis.
a shows a cross-sectional view of the drill saw assembly from the side in its drill mode.
b shows a cross-sectional view of the drill saw assembly from the side in its saw mode.
a shows a side profile of the internal mechanisms within the drill saw in its drill mode.
b shows a side profile of the internal mechanisms within the drill saw in its saw mode.
a shows a plan view of the view of
b shows a plan view of the view of
The present invention includes a compact, cordless power tool, producing rotation or reciprocation of a cutting tool blade depending on the mode selected.
The following description is to be read in conjunction with a review of
The inner workings are shown in cross section in
a and 4b illustrates the internal components of the drill saw from a side view with the casing and covers removed. The toggle switch 7 shown pulled back in drill mode in
A circuit board 23 such as diagrammatically illustrated in
Thus, as mentioned above, the drill saw according to the present invention operates in two modes: drill or saw mode. The ability to switch between the modes in one preferred embodiment advantageously uses mechanical alignment when the device is stopping. To accomplish this function circuit 23 takes control of the drill saw after the ON button is released. A small processor monitors the status of the trigger button. If the button is released the processor takes control of the drill saw motor and provides a slow constant velocity. When the drill saw approaches the alignment point magnet 27 embedded into tool holder 9 triggers a hall effects sensor 23a on the controller board 23. The processor stops the motor and returns control to the drill saw. The drill saw is thus aligned and slide pin 12 may be elevated or lowered between drill and saw mode.
A plan view of the internal components of the drill saw shown in
The center bevel gear 15 which is pressed into a bearing 24, drives an eccentric pin 16 in a circular path. This is converted to linear motion by the Scotch yoke T-slot 10a on the end of push rod 10. The tool holder 9 is supported and able to both translate along and rotate about axis D within the linear-rotary bearing 11, which has a low-friction coated surface.
Cutting tool blade 6, illustrated in use in
In particular, as better seen in
A chip-clearing slot 64 is provided on each side of the cutting tool blade to remove the debris from the pilot hole during the drilling operation. Loose chips of the material being cut slide along the chip-clearing slot as the cutting tool blade rotates, so as to fall from the pilot hole.
The end of the cutting tool blade that engages tool holder 9 has a chuck-engaging tang 6b with a positioning tab 6d that slides into the chuck 9d of the tool holder 9. A spring-loaded pin assembly or set-screw 9e on tool holder 9 engages the hole 6e located in the chuck-engaging tang 6b to hold the cutting tool firmly in place.
The diameter d1 of the spade drill bit is somewhat larger than the height d2 of the saw blade as seen in
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
