Patent Description:
The technology disclosed herein relates generally to fastener driving tools and is particularly directed to such tools of the type which use pressurized air to drive a piston that, in turn, causes a driver blade to force a fastener into a target workpiece. Embodiments are specifically disclosed which use lubricant-saturated porous media, such as a foam material, surrounding a portion of the outside of a piston, inside a working cylinder, to continually lubricate and clean the piston and working cylinder, enhancing the performance over a greater lifetime of the tool.

In an exemplary embodiment fastener driving tool, the lubricant-saturated porous media (e.g., foam material) has a first portion above a seal, and a second portion below a seal. This "double" foam material improves the lubrication below the seal, and also cleans beneath the seal.

In an exemplary embodiment, a two-part piston is mechanically attached to a driver assembly for a fastener driving tool. The upper portion of the piston is made of a non-metallic material and serves as guidance bearings against the cylinder wall that will not scratch the surface of the anodized cylinder wall. The guidance bearings are very beneficial in maintaining the position of the piston during a drive and return stroke. A rubber seal serves as the sealing surface. A lower portion of the piston is metal, which is capable of withstanding the stresses associated with the impact and other forces during the drive and return strokes. This lower portion is rigidly attached to the driver so that rocking and other changes in position of the driver are minimized.

Many conventional fastener driving tools use a piston to move a driver blade that forces a nail or staple into a target workpiece, as part of their operational cycle. These pistons are typically driven by pressurized gas, or in some cases, by combustion air. In a product line of pressurized gas tools known as FUSION® that are sold by Kyocera Senco Industrial Tools, Inc. , pressurized gas is stored in a main storage chamber and that gas is not vented to atmosphere, but instead is re-used multiple times, and can drive multiple driving strokes (including operational cycle counts in the tens of thousands, per charge of pressurized gas).

One of the challenges is to provide a lubricated surface between the piston and the inner cylinder wall to reduce friction, wear, and eventual loss of charge pressure. This surface is difficult to lubricate during the life of the tool due to the fact that the main storage chamber and the working cylinder are sealed. The motion of the piston tends to wipe the lubricant off the sliding surfaces over time, which then begins to wear the sealing surface. Such a worn sealing surface can result in pressure loss, as the charge of air escapes past the sealing surface.

In a conventional FUSION® tool sold by Kyocera Senco, such as illustrated in <FIG>, a working cylinder portion <NUM> of the tool, has a movable piston subassembly <NUM>. The tool has a main storage chamber <NUM>, exhibiting an outer pressure vessel wall <NUM>. Within the main storage chamber is a working cylinder <NUM>, and the working cylinder exhibits a cylinder wall <NUM>. Inside the cylinder wall <NUM> is a movable piston <NUM>, and above the piston is a gas pressure chamber <NUM>, whereas below the piston is a venting chamber <NUM> (in this view of <FIG>).

The piston <NUM> has a seal <NUM>, and above the seal (in this view) is a first slidable bearing <NUM>, and below the seal (in this view) is a second slidable bearing <NUM>. Between the second slidable bearing <NUM> and the seal <NUM> is a grease reservoir <NUM>. The grease reservoir provides lubrication for the tool.

At the lower end of the piston <NUM> is an opening in which a top end portion <NUM> of a driver <NUM> is held in place by a connecting pin <NUM>. The driver <NUM> exhibits driver teeth <NUM>, and extends out of the cylinder base <NUM>. Between the bottom of the main storage chamber <NUM>, and the cylinder base, is a stationary piston stop <NUM>.

The current FUSION® tool utilizes a lubricant that during manufacture is deposited on the cylinder wall and on the piston seal. This lubricant is important to the operation of the tool. However, the lubricant cannot be resupplied without disassembling the tool.

Another challenge is to construct the piston with a hard material that also slides along the cylinder wall. The current FUSION® tool, as depicted in <FIG>, illustrates the piston as a solid piece of material typically made of metal. Piston slidable bearings <NUM> and <NUM> are necessary to maintain the guidance of the piston during a drive and return stroke, without scoring the cylinder inner wall. The document <CIT> discloses a nailing apparatus. A strip of nails according to the disclosure can be wound into a spiral and is made up of a plurality of headed nails, the head of which is asymmetrical relative to the axis of the body and extends on only one side of said body, over a distance that is sufficiently small to prevent the initiation of buckling when the nail is driven in, said nails being juxtaposed so that their bodies are substantially contiguous and joined by a flexible separable connecting element, such as a flexible glue or adhesive tape, for example. The disclosure provides a nailing device using strips of spikes as defined above. The device comprises, in a body provided with a handle, a magazine of a spirally wound strip of spikes, a barrel for receiving one end of said strip of spikes, a punch for driving the spike of said end of the strip housed in said barrel, means for imparting, to said punch, a sharp impulse in the direction of the spike to be driven, means for leading the strip from the magazine to the barrel, and feed means for advancing the strip step by step and bringing, into the barrel, a new spike following the evacuation of the spike which was there. In an embodiment, of <CIT>, a ram is provided for actuating the punch, wherein the ram comprises a cylinder inside which is mounted a sleeve held in place, in said cylinder, by a cylinder plug screwed into the corresponding open lower end of the cylinder. A buffer, consisting of a natural or synthetic rubber washer interposed between the upper end of the liner and the bottom of the cylinder, serves as a shock absorber at the upper end of the stroke of the piston. In a similar manner, the other end of the stroke of the piston is damped by a buffer also made of natural or synthetic rubber which rests in the bottom of the cylinder plug. The piston is provided with two O-rings and a felt seal housed, respectively, in three annular grooves of the piston. The felt seal contains a lubricant, such as, for example, molybdenum disulfide, which ensures permanent lubrication. Between the piston and the bottom of the cylinder plug, there is interposed a helical compression spring whose role is to return the piston towards the bottom of the cylinder, when the jack is not supplied with compressed air.

Accordingly, it is an advantage to include a small volume or recess in the outer perimeter of the piston of a power tool that retains a porous media, such as foam material, that holds and dispenses a liquid lubricant, which increases the life of the piston, cylinder, and the piston seals.

It is another advantage to provide a lubricant used with a piston of a fastener driving tool, by storing the lubricant in open cell foam material in a recess of the piston outer surface, in which the foam holds and continuously deposits the lubricant along the piston and cylinder wall during the life of the tool. This provides improved wear characteristics that result in improved pressure retention over a longer tool life. The lubricant captured in the foam will tend to be constrained regardless of tool orientation.

It is yet another advantage to provide a two-part piston that is mechanically attached to a driver assembly for a fastener driving tool. The upper material is non-metal and serves as guidance bearings against the cylinder wall that will not scratch the surface of the anodized cylinder.

It is yet a further advantage to provide a piston with two separate portions of porous media, such as a foam material, for use in a fastener driving tool. At least the top foam portion stores and dispenses lubricant over the life of the tool. The lower foam portion acts as a debris "cleaner," removing debris that may enter the cylinder such as wood, gypsum, metallic particles, collation tape, sand, dirt, and moisture, or other items that are commonly found on construction jobsites. This debris build-up is due to the underside of the piston being exposed to ambient air.

Additional advantages and other novel features will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the technology disclosed herein.

To achieve the foregoing and other advantages, and in accordance with one aspect, a driver assembly according to claim <NUM> is provided.

In accordance with another aspect, a driver assembly according to claim <NUM> is provided.

Still other advantages will become apparent to those skilled in this art from the following description and drawings wherein there is described and shown a preferred embodiment in one of the best modes contemplated for carrying out the technology. As will be realized, the technology disclosed herein is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects within the scope defined by the appended claims. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the technology disclosed herein, and together with the description and claims serve to explain the principles of the technology. In the drawings:.

Reference will now be made in detail to the present preferred embodiment, an example of which is illustrated in the accompanying drawings, wherein like numerals indicate the same elements throughout the views.

It is to be understood that the technology disclosed herein 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 drawings. The technology disclosed herein is capable of other embodiments and of being practiced or of being carried out in various ways within the scope defined by the appended claims. Unless limited otherwise, the terms "connected," "coupled," and "mounted," and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms "connected" and "coupled" and variations thereof are not restricted to physical or mechanical connections or couplings. Furthermore, the terms "communicating with" and "in communications with" refer to two different physical or virtual elements that somehow pass signals or information between each other, whether that transfer of signals or information is direct or whether there are additional physical or virtual elements therebetween that are also involved in that passing of signals or information. Moreover, the term "in communication with" can also refer to a mechanical, hydraulic, or pneumatic system in which one end (a "first end") of the "communication" may be the "cause" of a certain impetus to occur (such as a mechanical movement, or a hydraulic or pneumatic change of state) and the other end (a "second end") of the "communication" may receive the "effect" of that movement/change of state, whether there are intermediate components between the "first end" and the "second end," or not.

The terms "first" and "second" preceding an element name, e.g., first inlet, second inlet, etc., are used for identification purposes to distinguish between similar or related elements, results or concepts, and are not intended to necessarily imply order, nor are the terms "first" and "second" intended to preclude the inclusion of additional similar or related elements, results or concepts, unless otherwise indicated.

Referring now to <FIG>, a piston subassembly for use in a fastener driving tool generally designated by the reference numeral <NUM> has two main halves: a piston top <NUM>, and a piston bottom <NUM>. The piston top <NUM> is constructed of a hard plastic, or other non-metallic material, preferably Delrin, whereas the piston bottom <NUM> is constructed of metal, preferably aluminum. The piston bottom is constructed with a stem that has a plurality of male threads <NUM>, and the piston top has a threaded opening to receive the stem, in which the threads are female. The piston top is threadably attached using the piston bottom's male threads (see <FIG>), such that both piston parts move together as a single piston subassembly <NUM>.

It should be noted that the piston design described above is merely a preferred embodiment for constructing the overall piston, and other two-piece piston designs could be used without departing from the principles of this technology. For example, as one alternative design, the two piston halves <NUM> and <NUM> may be attached to one another through any type of reliable mechanical connection, including a pin connector. Alternatively again, the two piston halves <NUM>, <NUM> could be constrained without mechanical fasteners so that they always move together. Furthermore, the gas pressure of the working cylinder <NUM> (see <FIG>) will tend to keep the top piston half <NUM> firmly pressed against the bottom piston half <NUM> under almost all circumstances of tool operation.

The general shape of piston subassembly <NUM> includes a cylindrical outer surface which has a circular cross-section, as can be seen in <FIG>. The center of the circular cross-section is located along a longitudinal axis of the piston, in which that longitudinal axis can be seen at "L" on <FIG>. It will be understood that the exact shape of the outer perimeter of the piston, and the exact shape of the corresponding inner surface of the cylinder sleeve, do not necessarily have to be precisely circular. Instead, these surfaces could have other geometric shapes, so long as they are "mating shapes," and still fall within the principles of the technology disclosed herein. With regard to the disclosure presented herein, it will be assumed that the piston indeed has a circular cross-section, and therefore, the inner surface of the cylinder sleeve is also circular.

A driver <NUM> (see <FIG>) has an upper attachment portion <NUM> that is installed during manufacture into an opening in the piston bottom half <NUM>. The piston bottom <NUM> exhibits two through openings <NUM> and <NUM> that are transverse to the driver opening. Two connecting pins <NUM> and <NUM> are used to secure the driver, at the driver upper portion <NUM>, to the piston bottom <NUM>. It will be understood that the various directional nomenclature provided above is with respect to the illustration of <FIG>, and the first embodiment can be used in many other angular positions, without departing from the principles of this technology. The use of these two connecting pins <NUM> and <NUM> help to keep the piston subassembly <NUM> aligned with the driver <NUM>.

It will be further understood that this piston subassembly <NUM> is designed to move in a reciprocating manner along a direction that will be referred to herein as a longitudinal axis. On <FIG>, such a longitudinal axis is designated by the letter "L. " The connecting pins <NUM> and <NUM> are placed in a perpendicular, transverse direction, which is indicated on <FIG> by the letter "T.

The piston top portion <NUM> has two circumferential recesses or grooves located on the outside surface of the piston. The upper groove (or recess) holds an annular-shaped material <NUM> that comprises a porous media such as foam, and the lower groove (or recess) holds an annular seal <NUM>, which in this illustrated embodiment is a lobed seal. (Note that the annular seal <NUM> is also sometimes referred to herein as a "perimeter seal," since it runs around the outer perimeter of the piston. ) The porous media <NUM> holds a liquid lubricant material (such as MOBIL VACTRA <NUM>™ oil, a premium ISO Viscosity Grade <NUM> slideway oil), and acts as a reservoir for the lubricant. The porous material can comprise various specific types of
materials, such as an open cell foam material, or a sponge-like foam material, or an air filter material that is resistant to oil. It is preferred that the foam material is soft, flexible, and nonabrasive.

An open cell foam material works well for the purposes described herein, and it will be understood that the terms "foam" or "foam material" as used hereinafter refer to all such types of porous media that are able to hold an appropriate liquid or grease lubricant material for use in these power tools. It will also be understood that, for the purposes of this disclosure, the phrase "circumferential recess" refers to a recess or "groove" in the outer surface of the piston, for example, regardless of the exact shape of the cross-section of that piston; in other words, the piston could have a circular or elliptical cross-section shape, or even a square or rectangular cross-section shape, yet the recess being referred herein would nevertheless be referred to as a "circumferential" recess, so that these recesses are better understood by the reader of this disclosure.

The porous media <NUM> may hold a variety of alternative liquid lubricant materials. The liquid lubricant material type used will alter the friction of the piston <NUM> during a lift cycle. It would be desirable for this liquid lubricant to be a lightweight oil having a viscosity around ISO <NUM> (about SAE 20W).

It should be noted that the "liquid" lubricant used for this purpose may contain solid particles as a form of grease in solution with a liquid; or possibly the "liquid" lubricant used could mainly comprise an appropriate grease material (with or without solid particles) that, when in use, acts as a semi-liquid or semi-solid material to spread out along the piston's surfaces as the piston undergoes reciprocating movements.

Preferably, the foam material <NUM> comprises open cell foam, such as a reticulated urethane foam, having an average cell density of about <NUM>-<NUM> pores per millimeter (<NUM>-<NUM> pores per inch). The foam material should be resistant to lubricating oils, and perhaps also to grease. Certain types of air filter material can be used for the foam material <NUM>, including pre-filters used for KOHLER® or BRIGGS & STRATTON® lawnmower engines.

The foam <NUM> is in constant contact with the inner cylinder wall, slowly dispensing lubricant over the life of the tool. The seal <NUM> is also in constant contact with the cylinder wall, and keeps the lubricant contained inside the cylinder; moreover, the seal retains the high gas pressure above the piston (in the variable displacement volume <NUM>). The cylinder and the seal may be pre-coated with an anti-seize lubricant, such as PERMATEX 133A™. (The anti-seize is wiped on, like a grease. ) The driver assembly according to the claimed invention has anti-seize grease pre-applied to the inner surface of the hollow cylinder. It is to be noted that the foam <NUM> does not act as a seal per se, but is intended to store and dispense lubricant along the cylinder wall. Also, a second seal "above" the foam <NUM> is not necessary, because any lubricant that moves "above" the seal will be re-used by subsequent piston movements.

It should also be noted that, once the tool has been fully assembled, the foam <NUM> becomes the sole source of the liquid lubricant for the cylinder and piston. More specifically, the foam acts as an inhibiting factor that prevents the lubricant from being dispensed too quickly, thereby increasing the normal life of the entire tool.

Although the statement in the preceding paragraph is true for certain embodiments, alternative embodiments are envisioned where a grease material is used in conjunction with a liquid lubricant, and the grease is typically not directly applied to the foam material. Instead, the grease is applied to the inner surface of the cylinder sleeve (cylinder wall <NUM>) before the piston is installed. The driver assembly according to the claimed invention has anti-seize grease pre-applied to the inner surface of the hollow cylinder.

As discussed above, various types of lubricants may work well in this fastener driving tool working cylinder. The liquid lubricants are generally to be applied to the foam <NUM>, as discussed above. The grease lubricants are generally to be applied to the seal <NUM> and/or to the inner surface of the cylinder wall <NUM>. The driver assembly according to the claimed invention has anti-seize grease pre-applied to the inner surface of the hollow cylinder. In an exemplary embodiment, both a grease material and a liquid material are simultaneously used.

If a grease material is to be used in the working cylinder <NUM>, then it would be applied to the inner surface of the cylinder before the piston subassembly <NUM> is installed therein. The driver assembly according to the claimed invention has anti-seize grease pre-applied to the inner surface of the hollow cylinder. Furthermore, the grease can also be applied to the seal <NUM>, as per the tool designer's choice. If grease is used at the seal <NUM>, that grease can be applied into the recess where the seal goes either before or after the seal <NUM> is installed onto the upper piston <NUM>. In general, it is preferred to install the foam <NUM> into its recess in the upper piston <NUM> before any liquid lubricant is applied to that foam <NUM>. (It is difficult to install a "wet" piece of foam into that groove or recess. ) Finally, it is likely better if at least some of the grease is applied "beneath"
the seal <NUM>-i.e., into the small space between the seal and the bottom surface of the groove. The more grease-and the more liquid lubricant-that can be "stored" in this working cylinder and piston combination, the longer that combination will properly operate.

Referring now to <FIG>, the piston subassembly <NUM> is shown integrated into a working cylinder portion of a driving tool, which is generally referred to by the reference numeral <NUM>. An outer wall <NUM> contains a main storage chamber <NUM>, in which a working cylinder <NUM> encloses the piston subassembly <NUM>. The working cylinder portion includes a cylinder base <NUM> that fully encloses the main storage chamber <NUM>. A gas pressure chamber <NUM> is contained inside the working cylinder, above the piston top <NUM>. The gas chamber <NUM> contains a variable volume, or "displacement volume," of pressurized gas that is used to drive the piston during operation. Beneath the piston bottom <NUM> is a cylinder "venting chamber" <NUM>, which vents to atmosphere.

During operation, the piston subassembly <NUM> slides along a cylinder inner wall (or "sleeve") <NUM> of the working cylinder <NUM>. The bearing surfaces <NUM>, <NUM>, and <NUM> of piston top <NUM> contact the cylinder wall <NUM> during normal movement. The piston bottom <NUM> is slightly smaller in diameter and does not contact the cylinder wall. As the piston subassembly slides along the cylinder wall, the piston is stopped by a stationary piston stop <NUM>.

These bearing surfaces <NUM>, <NUM>, and <NUM> are quite different than previous designs using metal pistons with insert bearings. In previous designs, the insert bearings provided a slidable surface along the cylinder wall, which allowed the piston to not touch the cylinder wall at all. In this new design, the bearing surfaces <NUM>, <NUM>, and <NUM> of the piston subassembly <NUM> actually touch and slide along the cylinder wall surface, and they act as low-friction guide bearing surfaces, as well.

The driver <NUM> moves with the piston subassembly <NUM> during operation. The driver exhibits driver teeth <NUM>. The driver moves along a driver track <NUM> through a guide body <NUM>. The guide body <NUM> is mounted beneath the cylinder base <NUM>. The guide body receives a fastener from a magazine (not shown), and guides the driver and the fastener to an exit portion of the tool, and into a workpiece. It will be understood that the various directional nomenclature provided above is with respect to the illustration of <FIG>, and the first embodiment can be used in many other angular orientations, without departing from the principles of this technology.

Referring now to <FIG>, a second piston subassembly for use in a fastener driving tool generally designated by the reference numeral <NUM> has two main halves: a piston top <NUM>, and a piston bottom <NUM>. The piston top <NUM> is constructed of a hard plastic, or other non-metallic material, preferably Delrin, whereas the piston bottom <NUM> is constructed of metal, preferably aluminum. The piston bottom is constructed with a stem that has a plurality of male threads <NUM>, and the piston top has a threaded opening to receive the stem, in which the threads are female. The piston top is threadably attached using the piston bottom's male threads (see <FIG>), such that both piston parts move together as a single piston subassembly. It should be noted that the two piston halves <NUM> and <NUM> may be attached to one another through any type of reliable mechanical connection, including a pin connector for example.

A driver <NUM> (see <FIG>) has an upper attachment portion <NUM> that is installed during manufacture into an opening in the piston bottom half <NUM>. The piston bottom <NUM> exhibits two through openings <NUM> and <NUM> that are transverse to the driver opening. Two connecting pins <NUM> and <NUM> are used to secure the driver, at the driver upper portion <NUM>, to the piston bottom <NUM>. It will be understood that the various directional nomenclature provided above is with respect to the illustration of <FIG>, and the first embodiment can be used in many other angular positions, without departing from the principles of this technology.

It will be again understood that this piston subassembly <NUM> is designed to move in a reciprocating manner along a direction that will be referred to herein as a longitudinal axis. On <FIG>, such a longitudinal axis is designated by the letter "L.

The piston top <NUM> has three circumferential recesses or grooves located on the outside surface of the piston. The upper groove holds a circular-shaped material <NUM> that comprises a porous media, such as a foam material, and the lower groove holds another circular-shaped material of porous media (e.g., foam material) <NUM>. The middle groove holds a circular seal <NUM>. (Note that the annular seal <NUM> is also sometimes referred to herein as a "perimeter seal," since it runs around the outer perimeter of the piston. Moreover, the porous media-or foam piece-<NUM> is sometimes referred to herein as a "first porous media," and the porous media-or foam piece-<NUM> is sometimes referred to herein as a "second porous media. ") In one embodiment, both foam pieces <NUM> and <NUM> hold a lubricant, and act as a reservoir for the lubricant. Preferably, the foam <NUM> and <NUM> comprises open cell foam. The foam <NUM> and <NUM> is in constant contact with the inner cylinder wall <NUM>, slowly dispensing lubricant over the life of the tool.

The seal <NUM> is also in constant contact with the cylinder, and keeps the lubricant contained inside the cylinder. It is to be noted that the foam pieces <NUM> and <NUM> do not act as a seal per se, but are intended to store and dispense lubricant along the cylinder. Also, a second seal "above" the foam <NUM> is not necessary, because any lubricant that moves "above" the seal will be re-used. The lower foam piece <NUM>, in addition to dispensing lubricant, also acts as a "wiper" or "catcher" for preventing outside debris from entering the seal's region of the tool in the area near the bottom of the cylinder <NUM>.

In an alternate embodiment, the foam <NUM> does not contain lubricant. Instead, the foam mainly acts as a "wiper" or "catcher" for debris that finds its way into the bottom area of the working cylinder <NUM>. If lubricant should happen to make its way past the seal <NUM> to this second foam piece <NUM>, then the foam piece <NUM> will re-distribute that lubricant. Optionally, the second foam piece <NUM> can receive a "light" amount of lubricant at the time of manufacture.

The second foam material <NUM> in the embodiment of <FIG> is positioned "below" the seal <NUM> for a reason. As discussed above, the foam <NUM> acts as a "wiper" or "catcher" to keep outside debris from reaching the seal <NUM>, thereby enhancing the life of the seal <NUM>, and thereby extending the life of the tool by maintaining a high air pressure in the main storage chamber and in the spaces "above" the top of the piston (above the surface <NUM>) for a longer time.

The second foam material <NUM> in the embodiment of <FIG> also acts as a "retainer" to keep the beneficial lubricant "above" that foam piece <NUM>; i.e., it will tend to keep the lubricant where the piston travels inside the working cylinder. And, as such a "retainer," the foam material <NUM> tends to keep the lubricant from traveling "down" (in this view) to the workpiece surface, when a fastener is driven.

It should be noted that the porous media (such as foam pieces) <NUM>, <NUM>, and <NUM> in the various embodiments disclosed herein do not need to be formed of a single piece of material. For example, the foam pieces could be arranged as a stack of foam pieces each having a smaller thickness, such as the pieces <NUM> and <NUM> on <FIG>. The top annular shape of this stack of smaller thickness foam pieces would have the shape depicted on <FIG>.

Furthermore, the porous media (such as foam pieces) <NUM>, <NUM>, and <NUM> in the various embodiments could be layered as different inner and outer diameters, such as the pieces <NUM> and <NUM> on <FIG>, in which the outer layer <NUM> covers the inner layer <NUM>. The top annular appearance of the shapes of those layered foam pieces would have the form illustrated on <FIG>. In this configuration, the inner and outer foam pieces <NUM> and <NUM> could have different physical characteristics, if desired. For example, the inner foam piece <NUM> could be selected for having an ability to maximize a large quantity of lubricant that can be retained, whereas the outer foam piece <NUM> could be selected for having a superior wicking ability, which would more readily transfer lubricant from its inner diameter to its outer diameter, and hence to the piston's outer perimeter surfaces near the cylinder inner wall.

It will be understood that the references to an inner diameter or an outer diameter of the hollow cylinder or of the piston, seal, or foam pieces can be referred to by other words, such as an inner (or outer) width, or an inner (or outer) dimension, while referring to the same or a similar portion of the parts that make up the power tool design disclosed herein. This is especially true if the piston and working cylinder are not perfectly round in shape. For example, the piston's outer shape (in cross-section) and the working cylinder's inner shape (in cross-section) could be elliptical, rather than circular, if desired.

It will be further understood that the description of the piston <NUM> in <FIG>, or the piston <NUM> in <FIG>, for example, could be described as having "a top outer surface, a bottom outer surface, and a side wall outer surface that extends between the top and bottom outer surfaces," with reference to the characteristics of the combination of the upper piston portion <NUM> (in <FIG>), the lower piston portion <NUM> (in <FIG>), and the side walls <NUM>, <NUM>, and <NUM> (in <FIG>), for example. Of course, the lower portion of the piston <NUM> also has side walls, which are not numbered on <FIG>.

Finally, it will be additionally understood that the piston subassembly <NUM>, or <NUM>, could be constructed of a single piece of material, if desired by the designer of the power tool for which it will be used, without departing from the principles of the technology disclosed herein. Certain modifications would likely have to be made for that type of piston construction, but certainly the foam pieces (porous media) used to dispense lubricant could still be included so as to provide some important benefits, as described herein.

Note that some of the embodiments illustrated herein do not have all of their components included on some of the figures herein, for purposes of clarity. To see examples of such outer housings and other components, especially for earlier designs, the reader is directed to other U. patents and applications owned by Senco. Similarly, information about "how" the electronic controller operates to control the functions of the tool is found in other U. patents and applications owned by Senco. Moreover, other aspects of the present tool technology may have been present in earlier fastener driving tools sold by the Assignee, Kyocera Senco Industrial Tools, Inc. , including information disclosed in previous U. patents and published applications. Examples of such publications are patent numbers <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>; also published <CIT> and published <CIT>.

It will be further understood that any type of product described herein that has moving parts, or that performs functions (such as computers with processing circuits and memory circuits), should be considered a "machine," and not merely as some inanimate apparatus. Such "machine" devices should automatically include power tools, printers, electronic locks, and the like, as those example devices each have certain moving parts. Moreover, a computerized device that performs useful functions should also be considered a machine, and such terminology is often used to describe many such devices; for example, a solid-state telephone answering machine may have no moving parts, yet it is commonly called a "machine" because it performs well-known useful functions.

As used herein, the term "proximal" can have a meaning of closely positioning one physical object with a second physical object, such that the two objects are perhaps adjacent to one another, although it is not necessarily required that there be no third object positioned therebetween. In the technology disclosed herein, there may be instances in which a "male locating structure" is to be positioned "proximal" to a "female locating structure. " In general, this could mean that the two male and female structures are to be physically abutting one another, or this could mean that they are "mated" to one another by way of a particular size and shape that essentially keeps one structure oriented in a predetermined direction and at an X-Y (e.g., horizontal and vertical) position with respect to one another, regardless as to whether the two male and female structures actually touch one another along a continuous surface. Or, two structures of any size and shape (whether male, female, or otherwise in shape) may be located somewhat near one another, regardless if they physically abut one another or not; such a relationship could still be termed "proximal. " Or, two or more possible locations for a particular point can be specified in relation to a precise attribute of a physical object, such as being "near" or "at" the end of a stick; all of those possible near/at locations could be deemed "proximal" to the end of that stick. Moreover, the term "proximal" can also have a meaning that relates strictly to a single object, in which the single object may have two ends, and the "distal end" is the end that is positioned somewhat farther away from a subject point (or area) of reference, and the "proximal end" is the other end, which would be positioned somewhat closer to that same subject point (or area) of reference.

It will be understood that the various components that are described and/or illustrated herein can be fabricated in various ways, including in multiple parts or as a unitary part for each of these components, without departing from the principles of the technology disclosed herein. For example, a component that is included as a recited element of a claim hereinbelow may be fabricated as a unitary part; or that component may be fabricated as a combined structure of several individual parts that are assembled together. But that "multipart component" will still fall within the scope of the claimed, recited element for infringement purposes of claim interpretation, even if it appears that the claimed, recited element is described and illustrated herein only as a unitary structure.

All documents cited in the Background and in the Detailed Description are not to be construed as an admission that it is prior art with respect to the technology disclosed herein.

Claim 1:
A driver assembly for use in a power tool, said driver assembly comprising:
a movable piston (<NUM>, <NUM>), exhibiting a top outer surface (<NUM>, <NUM>), a bottom outer surface (<NUM>, <NUM>), and a side wall outer surface extending between said top and bottom outer surfaces;
a hollow cylinder (<NUM>) having an inner surface (<NUM>) surrounding said side wall outer surface of the piston;
a movable driver (<NUM>) that is in mechanical communication with the piston;
a guide body (<NUM>) configured to guide said driver and configured to receive a fastener to be driven by the driver toward an exit portion of said guide body;
a first recess in said side wall outer surface of the piston; and
a porous media (<NUM>, <NUM>) positioned in said first recess along said side wall outer surface of the piston containing a liquid lubricant oil stored therein, wherein said porous media is configured to dispense said liquid lubricant oil onto said inner surface (<NUM>) of said hollow cylinder (<NUM>); and
an anti-seize grease pre-applied to said inner surface (<NUM>) of said hollow cylinder (<NUM>);
wherein: both said liquid lubricant oil and said anti-seize grease provide lubrication to at least a portion of said inner surface (<NUM>) of said hollow cylinder (<NUM>) proximal to said side wall outer surface of said piston (<NUM>, <NUM>), as said piston moves through said hollow cylinder.