Patent Description:
<CIT> (family member of <CIT>) is prior art in the sense of Article <NUM>(<NUM>) EPC.

According to its abstract, <CIT> describes two 18V-type rechargeable batteries which are attached in series so as to allow a 36V-type tabletop cutting device to be utilized. By utilizing the 18V batteries which are highly prevalent for electric tools, it is possible to use the 36V-type tabletop cutting device as well as to reduce costs for the batteries.

According to its abstract, <CIT> describes a motor drive circuit <NUM> that is provided with a changeover switch <NUM> for switching the connection form over into the condition (series mode) where two battery packs <NUM> and <NUM> are connected in series or the condition (parallel mode) where they are connected in parallel. Consequently, when the user turns on a main switch <NUM> in series mode by turning off the changeover switch <NUM>, an electric motor <NUM> start with the total voltage of the battery packs <NUM> and <NUM>, so that this system can perform heavy work. On the other hand, when he turns on the main switch <NUM> in parallel mode by turning on the changeover switch <NUM>, it starts with the average voltage of the battery packs <NUM> and <NUM>, so that the service life of the battery packs <NUM> and <NUM> extends sharply more than in the case of series mode.

The invention a miter saw comprising the combination of features of appended claim <NUM>.

With reference to <FIG> and <FIG>, a miter saw <NUM> includes a base assembly <NUM> and a saw unit <NUM> pivotably coupled to the base assembly <NUM> about a horizontal chop axis <NUM>. The base assembly <NUM> includes a base <NUM> and a turntable <NUM> that collectively define a work piece support surface <NUM>. The turntable <NUM> is pivotably coupled to the base <NUM> about a vertical miter axis <NUM> for performing a first angled cut (e.g., a miter cut) with the saw unit <NUM> on a work piece supported on the work piece support surface <NUM>. The turntable <NUM> and saw unit <NUM> are adjustable about the miter axis <NUM> to vary the miter angle of the saw unit <NUM> anywhere between a maximum left miter angle (e.g., <NUM> degrees) and a maximum right miter angle (e.g., <NUM> degrees).

The miter saw <NUM> also includes a bevel arm <NUM> pivotably coupling the saw unit <NUM> to the turntable <NUM> about a horizontal bevel axis <NUM> for performing a second angled cut (e.g., a bevel cut) with the saw unit <NUM> on a work piece supported on the work piece support surface <NUM>. With reference to <FIG> and <FIG>, the miter saw <NUM> also includes a bevel angle stop mechanism <NUM> for selectively limiting adjustment of the bevel angle anywhere between a maximum left bevel angle (e.g., <NUM> degrees) and a vertical bevel angle (e.g., <NUM> degrees), or anywhere between the maximum left bevel angle (e.g., <NUM> degrees) and a maximum right bevel angle (e.g., <NUM> degrees; <FIG>). In the illustrated embodiment of the miter saw <NUM>, the bevel angle stop mechanism <NUM> includes a pin <NUM> extending through an aperture <NUM> in the bevel arm <NUM> (<FIG> and <FIG>). The pin <NUM> includes a gripping portion <NUM> accessible by the user of the miter saw <NUM> to adjust the bevel angle of the saw unit <NUM>, and a distal end <NUM> protruding into a bevel arm mount <NUM> affixed to the turntable <NUM>. The bevel arm mount <NUM> includes a first stop <NUM> that is selectively engaged by the distal end <NUM> of the pin <NUM> coinciding with a vertical bevel angle of <NUM> degrees. In some embodiments of the miter saw <NUM>, the pin <NUM> may be biased toward the bevel arm mount <NUM> by a spring, thereby positioning the distal end <NUM> of the pin <NUM> in a location where it would contact the first stop <NUM> in response to pivoting the bevel arm <NUM>.

The illustrated bevel angle stop mechanism <NUM> also includes a protrusion <NUM> affixed to the bevel arm mount <NUM> and extending toward the bevel arm <NUM> (<FIG>), a second stop <NUM> affixed to the bevel arm <NUM> (<FIG>), and a third stop <NUM> affixed to the bevel arm <NUM> spaced <NUM> degrees circumferentially about the horizontal bevel axis <NUM>. The stops <NUM>, <NUM> are engageable with the protrusion <NUM> coinciding with the maximum left bevel angle (i.e., <NUM> degrees) and the maximum right bevel angle (i.e., <NUM> degrees), respectively. Specifically, engagement between the second stop <NUM> and the protrusion <NUM> coincides with the maximum left bevel angle, and engagement between the third stop <NUM> and the protrusion <NUM> coincides with the maximum right bevel angle.

Therefore, in the biased position of the pin <NUM>, the distal end <NUM> is engageable with the first stop <NUM> and the protrusion <NUM> is engageable with the second stop <NUM> to limit adjustment of the bevel angle anywhere between the vertical bevel angle of <NUM> degrees and the maximum left bevel angle of <NUM> degrees. When the user pulls the pin <NUM> rearward to an extent where the distal end <NUM> clears the first stop <NUM>, the bevel angle of the bevel arm <NUM> may be adjusted anywhere between the maximum left bevel angle of <NUM> degrees and the maximum right bevel angle of <NUM> degrees.

With continued reference to <FIG> and <FIG>, the miter saw <NUM> further includes a bevel angle lock mechanism <NUM> for securing the bevel arm <NUM> in any desired bevel angle between the maximum left and right bevel angles. The bevel angle lock mechanism <NUM> includes a threaded fastener <NUM> extending through an arcuate slot <NUM> in the bevel arm <NUM> and received in a corresponding threaded bore <NUM> in the bevel arm mount <NUM>. The illustrated arcuate slot <NUM> spans an arc length of at least about <NUM> degrees about the bevel axis <NUM> to provide sufficient clearance for the bevel arm <NUM> to be adjusted between the maximum left and right bevel angles. By tightening the threaded fastener <NUM> into the threaded bore <NUM>, a clearance which otherwise exists between the bevel arm <NUM> and the bevel arm mount <NUM> is closed, and a clamping force is exerted on the bevel arm <NUM> by a combination of the threaded fastener <NUM> and the bevel arm mount <NUM>. The clamping force, in turn, creates a frictional force between the bevel arm <NUM> and the bevel arm mount <NUM> that prevents the bevel arm <NUM> from being pivoted about the bevel axis <NUM>, thereby locking the bevel arm <NUM> and the saw unit <NUM> into a desired bevel angle.

With reference to <FIG> and <FIG>, the miter saw <NUM> also includes a fence assembly <NUM> against which a work piece on the work piece support surface <NUM> is abuttable during a cutting operation. The fence assembly <NUM> includes a stationary fence <NUM> affixed to a left side <NUM> of the base <NUM> and a removable fence <NUM> on a right side <NUM> of the base <NUM>, with the miter axis <NUM> being positioned between the stationary fence <NUM> and the removable fence <NUM>. The removable fence <NUM> is slidable relative to the base <NUM> in a direction <NUM> toward or away from the stationary fence <NUM> (e.g., in a direction transverse to the miter axis <NUM>). To perform a cutting operation with the saw unit <NUM> pivoted to the maximum right bevel angle (i.e., <NUM> degrees), the removable fence <NUM> is detached and removed from the base <NUM> (<FIG>).

As shown in <FIG>, the miter saw <NUM> further includes a pair of guide rails <NUM> interconnecting the saw unit <NUM> and the bevel arm <NUM> to permit the saw unit <NUM> to slide relative to the base assembly <NUM> in a direction <NUM> transverse to the chopping axis <NUM>. In the illustrated embodiment of the miter saw <NUM>, the guide rails <NUM> are supported within corresponding bores <NUM> in the bevel arm <NUM> by respective bearings (not shown) that facilitate sliding movement between the guide rails <NUM> and the bevel arm <NUM>. And, the saw unit <NUM> is connected to the guide rails <NUM> by a saw unit mount <NUM>, which includes a pivot joint <NUM> defining the chopping axis <NUM>.

With reference to <FIG>, the saw unit <NUM> includes a saw blade <NUM> rotatable about a blade axis <NUM> parallel with the chop axis <NUM> and a motor <NUM> having an output shaft <NUM> inclined relative to the blade axis <NUM> by an oblique included angle θ. In the illustrated embodiment of the miter saw <NUM>, the output shaft <NUM> has an integral pinion <NUM> enmeshed with a bevel gear <NUM> affixed to an arbor <NUM> of the saw blade <NUM>. Alternatively, a different transmission or gear train may be used to connect the motor <NUM> and the saw blade <NUM>. Also, in the illustrated embodiment of the miter saw <NUM>, the motor <NUM> is a brushless direct current (i.e., DC) motor. However, in other embodiments of the miter saw <NUM>, the motor <NUM> may be a brushed DC motor.

With reference to <FIG> and <FIG>, the saw unit <NUM> also includes a motor housing <NUM> in which the motor <NUM> is supported. The motor housing <NUM> includes a top surface <NUM> defining a plane <NUM> (<FIG>) that is substantially transverse to a saw blade plane <NUM> which, in turn, is perpendicular to the blade axis <NUM>. With reference to <FIG>, the saw unit <NUM> further includes dual battery receptacles <NUM> on the top surface <NUM> of the motor housing <NUM> that are generally positioned between the blade axis <NUM> and the chop axis <NUM> viewed from a side of the miter saw <NUM>. With reference to <FIG>, the battery receptacles <NUM> are sized and configured to receive respective post-style battery packs <NUM>, posts <NUM> of which are insertable into the respective battery receptacles <NUM> along parallel insertion axes <NUM> that are substantially transverse to the top surface plane <NUM>. Accordingly, when installed, the battery packs <NUM> are located on the top surface <NUM> of the motor housing <NUM> in a side-by-side relationship. In the illustrated embodiment of the miter saw <NUM>, the battery packs <NUM> are <NUM> volt lithium-ion power tool battery packs that are also usable with other power tools (e.g., drills, circular saws, and the like). The battery receptacles <NUM> are wired in series to provide the combined voltage of the batteries, <NUM> volts, to the motor <NUM> when activated. In other embodiments of the miter saw <NUM>, battery packs <NUM> having different nominal voltages (e.g., <NUM> volts, <NUM> volts, <NUM> volts, etc.) may be used.

As shown in <FIG>, the motor housing <NUM> and both battery packs <NUM> are positioned on a first side <NUM> of the saw blade plane <NUM>. In other words, for example, when the saw unit <NUM> is pivoted to a right bevel angle of about <NUM> degrees, the motor housing <NUM> and both battery packs <NUM> are located between the saw blade plane <NUM> and the work piece support surface <NUM>.

As shown in <FIG>, the saw unit <NUM> further includes a handle <NUM> extending from the motor housing <NUM> having a gripping portion <NUM> located at a distal end thereof. The saw unit <NUM> also includes a trigger <NUM> on the gripping portion <NUM> of the handle <NUM>, which activates the motor <NUM> in response to being depressed. Like the motor housing <NUM>, the handle <NUM> is also positioned on the first side <NUM> of the saw blade plane <NUM>. As shown in <FIG>, the gripping portion <NUM> also includes a beveled edge <NUM> on the side of the handle <NUM> furthest from the saw blade plane <NUM>. In the illustrated embodiment of the miter saw <NUM>, the beveled edge <NUM> defines an angle β of about <NUM> degrees relative to the top surface plane <NUM> (<FIG>).

When the saw unit <NUM> is positioned at the maximum right bevel angle (i.e., <NUM> degrees) as shown in <FIG>, the beveled edge <NUM> of the gripping portion <NUM> is substantially parallel with the work piece support surface <NUM>, with a distance D between the work piece support surface <NUM> and the beveled edge <NUM> being at least about <NUM> (<NUM> inches).

The beveled edge <NUM> also defines a plane <NUM> that is substantially parallel with the work piece support surface <NUM> when the saw unit <NUM> is positioned at the maximum right bevel angle. In the illustrated embodiment of the miter saw <NUM>, no portion of the motor housing <NUM> extends below the plane <NUM> of the beveled edge <NUM> when the saw unit <NUM> is pivoted to the maximum right bevel angle (i.e., <NUM> degrees), thereby leaving a clearance of at least about <NUM> (<NUM> inches) to accommodate a work piece on the work piece support surface <NUM> to perform a cutting operation. Such a clearance is sufficient for work pieces having a nominal height of <NUM> (<NUM> inches) (e.g., a <NUM> × <NUM> (<NUM> × <NUM> inch), a5 × <NUM> (2x6 inch), etc.), with which the miter saw <NUM> is commonly used.

Claim 1:
A miter saw (<NUM>) comprising:
a base assembly (<NUM>) including a support surface (<NUM>) operable to support a work piece;
a bevel arm (<NUM>) pivotably coupled to the base assembly about a horizontal bevel axis (<NUM>);
a saw unit (<NUM>) pivotably coupled to the bevel arm about a horizontal chop axis (<NUM>), the saw unit including:
a saw blade (<NUM>) rotatable about a blade axis (<NUM>) parallel with the chop axis, the saw blade operable to cut the work piece,
a motor (<NUM>) having an output shaft (<NUM>) inclined at an oblique included angle relative to the blade axis, and
a motor housing (<NUM>) in which the motor is supported;
at least one guide rail (<NUM>) coupling the saw unit to the base assembly to permit the saw unit to slide relative to the base assembly in the direction of the bevel axis; and
a battery (<NUM>) selectively electrically connectable with the motor to provide power to the motor;
wherein the bevel arm and saw unit are pivotable relative to the base assembly, from an orientation in which the saw blade is substantially vertical, in both a first direction about the bevel axis by a bevel angle of at least about <NUM> degrees and an opposite, second direction by a bevel angle of at least about <NUM> degrees;
wherein the saw blade (<NUM>) defines a blade plane (<NUM>) transverse to the blade axis (<NUM>), and wherein the motor housing (<NUM>) is positioned on a first side (<NUM>) of the blade plane; and wherein the motor housing (<NUM>) includes a top surface (<NUM>) generally defining a plane (<NUM>) that is
substantially transverse to the blade plane (<NUM>); and
characterized in that:
the battery is supported by the motor housing, the saw unit (<NUM>) further includes a battery receptacle (<NUM>) on the top surface of the motor housing (<NUM>), and
in that the top surface of the motor housing (<NUM>) is oriented substantially parallel to the support surface (<NUM>) of the base assembly (<NUM>) when the saw blade (<NUM>) is substantially vertical and in the fully engaged cutting orientation.