Patent Description:
<CIT> discloses an impact rotary tool attachment for measuring a torque applied to a shaft portion that transmits the impacting force produced by an impact rotary tool to a tip tool.

<CIT> describes a router attachment that is mounted to a conventional screw gun with a router bit mounted in a chuck. The screwdriver tip and the screwdriver shaft of the screw gun are received in the router housing and drive the input shaft which in turn, via a step-up gear, drives the output shaft and thus the router bit. The output shaft therefore rotates at a higher rate than the input shaft. The router attachment is used in the construction of interior walls and partitions covered in drywall material so that only one tool is needed to both install the screws and to cut the sheets of drywall.

<CIT> describes a rotary hand tool attachment that is intended for coupling to a rotary power hand tool of the type that has a housing with a substantially cylindrical nose portion and a motor having an output shaft with a mounting coupling for receiving a drive shaft extending forwardly therefrom.

<CIT> describes an angle impact tool that comprises a handle assembly extending along a first axis and supporting a motor, the motor including a shaft configured to rotate about the first axis, and a work attachment coupled to the handle assembly.

<CIT> describes an equipment or fixture comprising an internal combustion engine, a reduction member or unit coupled to the engine through a friction clutch member, a tool holding assembly drivingly coupled to the reduction unit and ventilating means for cooling the clutch.

<CIT> describes a right angle drive including an input shaft, an output shaft, a housing, a pair of input shaft bearings and a pair of output shaft bearings.

<CIT> describes an electric drill multifunctional converter having a shell, a rocking bar that is arranged on the shell through a bearing, wherein one end of said rocking bar is a rotating shaft connected with the mounting hole of the drill head, and the other end has an incline, on which a connecting shaft is provided.

<CIT> describes an adaptor which is designed to be attached to an existing screwgun having a bit with a polygonally shaped end. The adaptor has a recess designed to drivingly receive the hexagonally shaped end of the bit and may be fixedly attached to the existing screwgun.

<CIT> describes an electrical connector crimping tool head comprising a frame and a ram movably connected to the frame. The ram comprises a first member and a second member longitudinally movable along the first member.

There has been a growing demand for an impact rotary tool attachment that comes in handy when the user needs to have various types of machining work done using an impact rotary tool.

In view of the foregoing background, it is therefore an object of the present disclosure to provide a tool system comprising an impact rotary tool attachment, which is designed to allow the user to have various types of machining work done more easily and more conveniently using an impact rotary tool.

This object is solved by a tool system having the features of independent claim <NUM>. Additional embodiments are defined in the dependent claims.

Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. In the following description, any constituent element, having the same function and forming part of multiple embodiments, will be designated by the same reference numeral and a redundant description thereof will be omitted herein. Note that the embodiment to be described below is only an exemplary one of various embodiments of the present disclosure and should not be construed as limiting. Rather, the exemplary embodiment may be readily modified in various manners depending on a design choice or any other factor without departing from the scope of the present disclosure. The drawings to be referred to in the following description of embodiments are all schematic representations. That is to say, the ratio of the dimensions (including thicknesses) of respective constituent elements illustrated on the drawings does not always reflect their actual dimensional ratio. Note that the arrows indicating respective directions on the drawings are only examples and should not be construed as defining the directions in which the tool system <NUM> is supposed to be used. Furthermore, those arrows indicating the respective directions are shown on the drawings only for the sake of description and are insubstantial ones.

As used herein, if one direction is "perpendicular to" another direction, this expression means that these two directions are substantially perpendicular to each other. That is to say, these two directions may naturally form an angle of exactly <NUM> degrees between themselves but may also form an angle within <NUM> ± several degrees (e.g., <NUM> ± less than <NUM> degrees) between themselves.

First, an overview of a tool system <NUM> according to a first embodiment will be described with reference to <FIG>, <FIG>, and <FIG>.

As shown in <FIG>, a tool system <NUM> according to the first embodiment includes an impact rotary tool <NUM> and an impact rotary tool attachment <NUM> (hereinafter referred to as an "attachment <NUM>"). As shown in <FIG>, the attachment <NUM> is attached to, and used integrally with, the impact rotary tool <NUM>.

The impact rotary tool <NUM> according to this embodiment operates with motive power (such as electric power) supplied from a motive power source such as a battery pack <NUM>. Specifically, as shown in <FIG>, a motor <NUM> supplied with electric power from the battery pack <NUM> (see <FIG>) turns to transmit rotational driving force to a first output shaft <NUM>. If a tip tool such as a screwdriver bit is attached to the first output shaft <NUM>, a fastener such as a screw as the target of machining work may be attached to the impact rotary tool <NUM>.

In addition, the impact rotary tool <NUM> according to this embodiment further includes an impact mechanism <NUM>. The impact mechanism <NUM> applies, when the load torque of the first output shaft <NUM> exceeds a predetermined level, impacting force in the direction of rotation to the first output shaft <NUM>. This allows the impact rotary tool <NUM> to give a greater fastening torque to the workpiece such as a fastener. Examples of such impact rotary tools <NUM> include an impact wrench, an impact screwdriver, and various other types of tools. The impact rotary tool <NUM> according to this embodiment is implemented as an impact screwdriver including the first output shaft <NUM> which may hold a bit such as a screwdriver bit thereon.

The attachment <NUM> is attached to the impact rotary tool <NUM> as shown in <FIG>. The attachment <NUM> includes an input shaft <NUM>, to which rotational driving force is transmitted from the first output shaft <NUM> of the impact rotary tool <NUM>, and a second output shaft <NUM>, to which the rotational driving force is transmitted from the input shaft <NUM> as shown in <FIG>. The attachment <NUM> further includes a driving force conversion mechanism <NUM> for transmitting the rotational driving force from the input shaft <NUM> to the second output shaft <NUM>. The driving force conversion mechanism <NUM> translates, when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>, the rotational axis Ax0 of the rotation produced by the rotational driving force.

The attachment <NUM> according to this embodiment includes the driving force conversion mechanism <NUM>, thus allowing the user to have even a type of machining work, which has been troublesome to do with a known impact rotary tool, done easily.

Next, a detailed configuration for the tool system <NUM> according to this embodiment will be described with reference to <FIG>.

As shown in <FIG>, the tool system <NUM> according to this embodiment includes the impact rotary tool <NUM> and the attachment <NUM>. Also, as shown in <FIG>, the attachment <NUM> is fixed to the impact rotary tool <NUM> by an attachment mechanism <NUM> (see <FIG>) of the attachment <NUM> at a tip portion <NUM> (see <FIG>) of the impact rotary tool <NUM>.

First, a configuration for the impact rotary tool <NUM> of the tool system <NUM> according to this embodiment will be described with reference to <FIG>. In the following description, the direction in which a drive shaft <NUM> (see <FIG>) to be described later and the first output shaft <NUM> are arranged side by side is hereinafter defined as a forward/backward direction with the first output shaft <NUM> supposed to be located forward of the drive shaft <NUM> (i.e., with the drive shaft <NUM> supposed to be located backward of the first output shaft <NUM>). In addition, in the following description, the direction in which a barrel <NUM> and a grip portion <NUM> to be described later are arranged one on top of the other will be hereinafter defined as an upward/downward direction with the barrel <NUM> supposed to be located upward of the grip portion <NUM> (i.e., with the grip portion <NUM> supposed to be location downward of the barrel <NUM>).

As shown in <FIG> and <FIG>, the impact rotary tool <NUM> according to this embodiment is used in the tool system <NUM>. A rechargeable battery pack <NUM> is attached removably to the impact rotary tool <NUM>. The impact rotary tool <NUM> according to this embodiment operates by being powered by the battery pack <NUM>. That is to say, the battery pack <NUM> is a power supply that supplies a current for driving the motor <NUM> (see <FIG>). In this embodiment, the battery pack <NUM> is not a constituent element of the impact rotary tool <NUM>. However, this is only an example and should not be construed as limiting. Alternatively, the impact rotary tool <NUM> may include the battery pack <NUM> as one of constituent elements thereof. The battery pack <NUM> includes an assembled battery formed by connecting a plurality of secondary batteries (such as lithium-ion batteries) in series and a case in which the assembled battery is housed.

As shown in <FIG>, the impact rotary tool <NUM> includes a body <NUM>, the motor <NUM>, a transmission mechanism <NUM>, and a trigger volume <NUM>.

As shown in <FIG>, the body <NUM> houses the motor <NUM> and a part of the transmission mechanism <NUM>. The body <NUM> includes the barrel <NUM>, the grip portion <NUM>, and a battery attachment portion <NUM> as shown in <FIG>. The barrel <NUM> has the shape of a cylinder having an opening at the tip (front end) thereof and a closed bottom at the rear end thereof. The grip portion <NUM> protrudes downward from the barrel <NUM>. The battery attachment portion <NUM> is configured such that the battery pack <NUM> is attachable to, and removable from, the battery attachment portion <NUM>. In this embodiment, the battery attachment portion <NUM> is provided at the tip portion (i.e., at the bottom) of the grip portion <NUM>. In other words, the barrel <NUM> and the battery attachment portion <NUM> are coupled together via the grip portion <NUM>.

The trigger volume <NUM> protrudes from the grip portion <NUM>. The trigger volume <NUM> is an operating member for accepting an operating command for controlling the rotation of the motor <NUM> (see <FIG>). The ON/OFF states of the motor <NUM> may be switched by pulling the trigger volume <NUM>. In addition, the rotational velocity of the motor <NUM> is adjustable by the manipulative variable indicating how deep the trigger volume <NUM> has been pulled. Specifically, the greater the manipulative variable is, the higher the rotational velocity of the motor <NUM> becomes.

The motor <NUM> shown in <FIG> may be a brushless motor, for example. The motor <NUM> includes a rotary shaft <NUM> and transforms the electric power supplied from the battery pack <NUM> (see <FIG>) into the rotational driving force to be applied to the rotary shaft <NUM>.

The transmission mechanism <NUM> shown in <FIG> is located forward of the motor <NUM> in the internal space of the barrel <NUM>. The transmission mechanism <NUM> includes the impact mechanism <NUM> and a planetary gear mechanism <NUM>. The impact mechanism <NUM> includes the drive shaft <NUM>, a hammer <NUM>, a return spring <NUM>, an anvil <NUM>, and two steel balls (rolling elements) <NUM>. The rotational driving force of the rotary shaft <NUM> of the motor <NUM> is transmitted to the drive shaft <NUM> via the planetary gear mechanism <NUM>. The drive shaft <NUM> is provided between the motor <NUM> and the first output shaft <NUM>.

The hammer <NUM> moves with respect to the anvil <NUM> to apply rotational impact to the anvil <NUM> with the motive power supplied from the motor <NUM>. The hammer <NUM> includes a hammer body <NUM> and two projections <NUM> (only one of which is shown in <FIG>). The two projections <NUM> protrude from one surface, facing the first output shaft <NUM>, of the hammer body <NUM>. The hammer body <NUM> has a through hole <NUM>, through which the drive shaft <NUM> is passed. In addition, the hammer body <NUM> has two groove portions <NUM> on an inner peripheral surface of the through hole <NUM>. The drive shaft <NUM> has two groove portions <NUM> on an outer peripheral surface thereof. The two groove portions <NUM> are connected together. The two steel balls <NUM> are interposed between the two groove portions <NUM> and the two groove portions <NUM>. These two groove portions <NUM>, two groove portions <NUM>, and two steel balls <NUM> together form a cam mechanism. While the two steel balls <NUM> are moving, the hammer <NUM> is not only movable along the axis of the drive shaft <NUM> with respect to the drive shaft <NUM> but also rotatable with respect to the drive shaft <NUM>. As the hammer <NUM> moves along the axis of the drive shaft <NUM> toward, or away from, the anvil <NUM>, the hammer <NUM> rotates with respect to the drive shaft <NUM>.

The anvil <NUM> includes the first output shaft <NUM>, two impacting portions <NUM>, and a base portion <NUM>. The base portion <NUM> has a disk shape when viewed in plan in the forward/backward direction. The center of the base portion <NUM> substantially agrees with the center axis of the drive shaft <NUM>. The first output shaft <NUM> holds either a tip tool or a coupling shaft <NUM> (see <FIG>) thereon. The first output shaft <NUM> has a cylindrical shape and protrudes forward from the base portion <NUM>. The two impacting portions <NUM> protrude from the base portion <NUM> along the radius of the base portion <NUM>. The anvil <NUM> faces the hammer body <NUM> along the axis of the drive shaft <NUM>. Also, while the impact mechanism <NUM> is not performing the impacting operation, the hammer <NUM> and the anvil <NUM> rotate along with each other with the two projections <NUM> of the hammer <NUM> and the two impacting portions <NUM> of the anvil <NUM> kept in contact with each other in the direction in which the drive shaft <NUM> rotates. Thus, at this time, the drive shaft <NUM>, the hammer <NUM>, and the anvil <NUM> (first output shaft <NUM>) rotate along with each other.

The return spring <NUM> is interposed between the hammer <NUM> and the planetary gear mechanism <NUM>. The return spring <NUM> according to this embodiment is configured as a conical coil spring. The impact mechanism <NUM> further includes a plurality of (e.g., two in the example illustrated in <FIG>) steel balls <NUM> and a ring <NUM>, both of which are interposed between the hammer <NUM> and the return spring <NUM>. This makes the hammer <NUM> rotatable with respect to the return spring <NUM>. The hammer <NUM> receives, from the return spring <NUM>, force directed toward the first output shaft <NUM> in the direction aligned with the axis of the drive shaft <NUM>.

In the following description, the movement of the hammer <NUM> toward the anvil <NUM> along the axis of the drive shaft <NUM> will be hereinafter referred to as a "forward movement of the hammer <NUM>. " On the other hand, the movement of the hammer <NUM> away from the anvil <NUM> along the axis of the drive shaft <NUM> will be hereinafter referred to as a "backward movement of the hammer <NUM>.

The impact mechanism <NUM> starts performing the impacting operation when the load torque becomes equal to or greater than a predetermined value. Specifically, as the load torque increases, the proportion of the component of force that causes the hammer <NUM> to move backward increases with respect to the force produced between the hammer <NUM> and the anvil <NUM>. When the load torque becomes equal to or greater than a predetermined value, the hammer <NUM> starts moving backward while compressing the return spring <NUM>. Then, as the hammer <NUM> moves backward, the hammer <NUM> rotates with the two projections <NUM> of the hammer <NUM> allowed to go over the two impacting portions <NUM> of the anvil <NUM>. Thereafter, the hammer <NUM> is caused to start moving forward upon receiving the force of restitution from the return spring <NUM>. Then, when the drive shaft <NUM> makes approximately a half turn, the two projections <NUM> of the hammer <NUM> collide against the side surfaces of the two impacting portions <NUM> of the anvil <NUM>. In this impact mechanism <NUM>, every time the drive shaft <NUM> makes approximately a half turn, the two projections <NUM> of the hammer <NUM> collide against the two impacting portions <NUM>. That is to say, every time the drive shaft <NUM> makes approximately a half turn, the hammer <NUM> applies rotational impact to the anvil <NUM>.

In this manner, in this impact mechanism <NUM>, collision occurs repeatedly between the hammer <NUM> and the anvil <NUM>. The torque produced by this collision allows fasteners such as screws, bolts, or nuts to be fastened more tightly than in a situation where no collision occurs between the hammer <NUM> and the anvil <NUM>.

Such a transmission mechanism <NUM> is housed in the metallic hammer case <NUM>. The hammer case <NUM> has a circular through hole <NUM>, which is provided through a front surface <NUM> thereof and allows the first output shaft <NUM> to pass therethrough. In addition, the hammer case <NUM> also includes a protruding portion <NUM> protruding forward from a circumferential edge of the through hole <NUM>. The protruding portion <NUM> has a cylindrical shape. The protruding portion <NUM> has a plurality of (e.g., two in the example illustrated in <FIG>) recesses <NUM>, which are provided on an outer peripheral surface thereof. As shown in <FIG>, pawls <NUM> of the attachment <NUM> are engaged with the recesses <NUM>.

The first output shaft <NUM> has an insert hole <NUM> and a fixing mechanism <NUM>. Into the insert hole <NUM>, a tip tool such as a screwdriver bit or the coupling shaft <NUM> (bar-shaped member) of the attachment <NUM> is attached. The insert hole <NUM> according to this embodiment has a regular hexagonal shape when viewed along the axis of the coupling shaft <NUM> (i.e., in the forward/backward direction). As used herein, the "regular hexagonal shape" refers to not only a regular hexagon, of which the six sides have exactly the same length and the six interior angles are exactly equal to each other, but also a shape which is similar to, and may be regarded as, a regular hexagon.

For example, if a screwdriver bit is attached to the first output shaft <NUM>, the transmission mechanism <NUM> transmits the rotational driving force of the rotary shaft <NUM> of the motor <NUM> to the screwdriver bit via the first output shaft <NUM>, thus causing the screwdriver bit to turn. Causing the screwdriver bit to turn while keeping in contact with a fastener (such as a screw) enables machining work such as fastening or loosening the fastener to be performed. The transmission mechanism <NUM> includes the impact mechanism <NUM>. The impact rotary tool <NUM> according to this embodiment is an electric impact screwdriver that enables a screw to be fastened while making the impact mechanism <NUM> perform an impacting operation. The impacting operation applies impacting force to the fastener, such as a screw, via the first output shaft <NUM>.

Meanwhile, if the coupling shaft <NUM> of the attachment <NUM> is attached to the first output shaft <NUM> (see <FIG>), the transmission mechanism <NUM> transmits the rotational driving force of the rotary shaft <NUM> of the motor <NUM> to the coupling shaft <NUM> via the first output shaft <NUM>. This causes the coupling shaft <NUM> to turn. Causing the coupling shaft <NUM> to turn allows the coupling shaft <NUM> to transmit the rotational driving force to the input shaft <NUM> of the attachment <NUM>. It will be described later in the "(<NUM>) Configuration for attachment" section how the attachment <NUM> operates after the rotational driving force has been transmitted to the input shaft <NUM>.

The fixing mechanism <NUM> includes a plurality of (e.g., two in the example illustrated in <FIG>) holes <NUM>, a plurality of (e.g., two in the example illustrated in <FIG>) steel balls <NUM> (spherical members), a spring <NUM>, a bit holder <NUM>, and another spring <NUM>. The fixing mechanism <NUM> is a mechanism for holding a tip tool such as a screwdriver bit with respect to the impact rotary tool <NUM>. The two holes <NUM> are respectively provided at upper and lower ends of the insert hole <NUM> so as to be located forward of the tip of the protruding portion <NUM> of the hammer case <NUM>. Each of the two holes <NUM> is a hole with the shape of an ellipse, of which the major axis is aligned with the forward/backward direction. The two steel balls <NUM> are respectively fitted into the two holes <NUM>. The bit holder <NUM> has the shape of a cylinder, of which the front and rear surfaces are open, and covers the outer periphery of the first output shaft <NUM> at the tip of the first output shaft <NUM>. The spring <NUM> is a helical spring covering the outer periphery of the first output shaft <NUM> between the first output shaft <NUM> and bit holder <NUM>. When a tip tool is inserted into the insert hole <NUM>, the tip tool pushes the two steel balls <NUM> obliquely upward and obliquely downward, respectively, by overcoming the elastic force of the spring <NUM>. In a state where the tip tool is inserted into the insert hole <NUM>, the two steel balls <NUM> are allowed to clamp the tip tool between themselves by the elastic force of the spring <NUM>. If the tip tool is provided with a groove to receive the steel balls <NUM>, then the steel balls <NUM> are fitted into the groove of the tip tool, thereby fixing the tip tool with respect to the impact rotary tool <NUM>. The spring <NUM> is a helical spring which is located forward of the spring <NUM> and covers the outer periphery of the first output shaft <NUM> between the first output shaft <NUM> and the bit holder <NUM>. Causing the bit holder <NUM> to move forward against the elastic force applied by the spring <NUM> leaves a space between the bit holder <NUM> and the spring <NUM> in the upward/downward direction between the two holes <NUM>. The steel balls <NUM> fitted into the groove of the tip tool may be disengaged from the groove by making the two steel balls <NUM> move into the space.

As described above, the two (i.e., a pair of) steel balls <NUM> are movable in both the forward/backward direction and the upward/downward direction. In a state where the tip tool does not push the two steel balls <NUM> obliquely upward and obliquely downward, respectively, by overcoming the elastic force of the spring <NUM> (i.e., in a default state), the gap distance as measured in the upward/downward direction between the two steel balls <NUM> is a minimum gap distance W1. Meanwhile, the coupling shaft <NUM> of the attachment <NUM> according to this embodiment has no groove into which the steel balls <NUM> are fitted.

As can be seen, the first output shaft <NUM> is a constituent element for holding a tip tool such as a screwdriver bit. Note that in this embodiment, the tip tool is not one of the constituent elements of the impact rotary tool <NUM>.

Next, a configuration for the attachment <NUM> of the tool system <NUM> according to this embodiment will be described with reference to <FIG>.

As shown in <FIG>, the attachment <NUM> according to this embodiment includes a housing <NUM>, the input shaft <NUM>, the coupling shaft <NUM>, a second output shaft <NUM>, the attachment mechanism <NUM>, and the driving force conversion mechanism <NUM>.

The housing <NUM> houses the input shaft <NUM>, the coupling shaft <NUM>, a part of the second output shaft <NUM>, a part of the attachment mechanism <NUM>, and the driving force conversion mechanism <NUM>.

The coupling shaft <NUM> couples the first output shaft <NUM> to the input shaft <NUM> and drives the first output shaft <NUM> and the input shaft <NUM> integrally with each other. The coupling shaft <NUM> transmits the rotational driving force of the first output shaft <NUM> from the first output shaft <NUM> to the input shaft <NUM>.

In addition, the coupling shaft <NUM> further includes an input part <NUM> and an output part <NUM>.

The input part <NUM> is located at one end along the axis of the coupling shaft <NUM> (i.e., in the forward/backward direction), to which the rotational driving force is transmitted from the impact rotary tool <NUM>. In addition, the input part <NUM> is a part to be inserted into the insert hole <NUM> of the impact rotary tool <NUM>. The input part <NUM> has a regular hexagonal prism shape as a whole and has a shape corresponding to that of the insert hole <NUM> of the impact rotary tool <NUM>. Specifically, the cross-sectional shape of the input part <NUM> is the same as the shape of the insert hole <NUM>. For example, if the insert hole <NUM> has a regular hexagonal shape as in this embodiment, then the input part <NUM> has a regular hexagonal cross-sectional shape and the insert hole <NUM> also has a regular hexagonal shape. As used herein, the "regular hexagonal prism shape" refers to not only a regular hexagonal prism, of which the bottom and top surfaces both have a regular hexagonal shape, in which six sides, each connecting a pair of associated vertices of the bottom and top surfaces, have an equal length, and in which those six sides, the bottom surface, and the top surface intersect with each other at right angles, but also a shape which is similar to, and may be regarded as, a regular hexagonal prism as well.

The input part <NUM> has a thinner shaft portion <NUM>. The thinner shaft portion <NUM> includes a part thinner than the output part <NUM> in at least a range from a position where the thinner shaft portion <NUM> faces the two steel balls <NUM> to one tip located closer to the impact rotary tool <NUM>. As shown in <FIG>, the thinner shaft portion <NUM> includes a part thinner than the output part <NUM> in a direction in which the thinner shaft portion <NUM> faces the two steel balls <NUM>. This allows the attachment <NUM> according to this embodiment to be inserted into, and removed from, the impact rotary tool <NUM> more easily.

The thinner shaft portion <NUM> according to this embodiment is provided with a plurality of recesses <NUM> (see <FIG>) in the range from the position where the thinner shaft portion <NUM> faces the two steel balls <NUM> to the tip located closer to the impact rotary tool <NUM>, and therefore, is thinner than the output part <NUM>. In the example illustrated in <FIG> and <FIG>, when measured in a direction (upward/downward direction) perpendicular to the axis of the coupling shaft <NUM> (forward/backward direction), the width W2 between the two (i.e., the pair of) recesses <NUM> of the thinner shaft portion <NUM> is smaller than the width W3 of the output part <NUM>. On the other hand, the rest of the input part <NUM> according to this embodiment, other than the thinner shaft portion <NUM>, has the same shape and the same dimension as the output part <NUM>. That is to say, when measured in the upward/downward direction, the width of the non-thinner shaft portion <NUM> of the input part <NUM> is equal to the width W3 of the output part <NUM>.

Furthermore, the width W2 between the pair of recesses <NUM> according to this embodiment is equal to or less than the minimum gap distance W1 (see <FIG>) between the pair of steel balls <NUM>. In other words, when measured in the upward/downward direction, the width W2 of the part, facing the pair of steel balls <NUM>, of the thinner shaft portion <NUM> is equal to or less than the minimum gap distance W1 between the pair of steel balls <NUM>. Stated otherwise, it can also be said that the width W2 is the width of the thinner shaft portion <NUM> as measured in the direction in which the thinner shaft portion <NUM> faces the steel balls <NUM>. Since the width W2 between the pair of recesses <NUM> is equal to or less than the minimum gap distance W1 between the pair of steel balls <NUM>, the thinner shaft portion <NUM> according to this embodiment may reduce the pressing force applied by the steel balls <NUM>.

As shown in <FIG>, the thinner shaft portion <NUM> is provided with the recess <NUM> in each of the six side surfaces of its regular hexagonal prism. In other words, the thinner shaft portion <NUM> according to this embodiment has six recesses <NUM>.

As shown in <FIG>, each of the six recesses <NUM> has the shape of an arc, corresponding to the shape of the steel balls <NUM>, when viewed in plan along the axis of the coupling shaft <NUM>.

In addition, the thinner shaft portion <NUM> also has six raised portions <NUM>, each of which is provided between an associated pair of adjacent recesses <NUM> out of the six recesses <NUM>. In this example, each of the six raised portions <NUM> according to this embodiment corresponds to an associated one of the six vertices of the regular hexagon. When the input part <NUM> is inserted into the insert hole <NUM> of the impact rotary tool <NUM>, the six raised portions <NUM> are in contact with the inner walls <NUM> of the insert hole <NUM>. Since the raised portions <NUM> and the inner walls <NUM> of the insert hole <NUM> are in contact with each other, the rotational driving force is transmitted from the impact rotary tool <NUM> to the thinner shaft portion <NUM> as well.

As shown in <FIG>, the output part <NUM> is a part extended forward in the forward/backward direction from the input part <NUM> and located on an end of transmitting the rotational driving force to the input shaft <NUM>. The output part <NUM> according to this embodiment has a regular hexagonal shape corresponding to the shape of the insert hole <NUM> of the input shaft <NUM>. Specifically, the cross-sectional shape of the output part <NUM> is the same as the shape of the insert hole <NUM>. For example, if the output part <NUM> has a regular hexagonal prism shape as in this embodiment, then the output part <NUM> has a regular hexagonal cross-sectional shape and the insert hole <NUM> also has a regular hexagonal shape. The output part <NUM> according to this embodiment is press-fitted into the insert hole <NUM> of the input shaft <NUM>. In other words, the coupling shaft <NUM> and the input shaft <NUM> according to this embodiment are formed integrally with each other and the coupling shaft <NUM> and the input shaft <NUM> are driven integrally with each other.

The attachment mechanism <NUM> is used to fix the housing <NUM> of the attachment <NUM> to the tip portion <NUM> of the impact rotary tool <NUM>. The attachment mechanism <NUM> includes a plurality of (e.g., two in the example illustrated in <FIG>) pawls <NUM> and a plurality of (e.g., two in the example illustrated in <FIG>) springs <NUM>.

Each of the pawls <NUM> includes a surface portion <NUM>, a base portion <NUM>, a shaft portion <NUM>, a protruding portion <NUM>, and a hook <NUM>. The surface portion <NUM> is exposed on the housing <NUM> and has a rectangular shape when viewed in plan in the upward/downward direction. The base portion <NUM> protrudes toward the coupling shaft <NUM> under a rear part of the surface portion <NUM>. The shaft portion <NUM> is a shaft extending in the rightward/leftward direction and provided for a tip <NUM>, facing the coupling shaft <NUM>, of the base portion <NUM>. The shaft portion <NUM> is rotatably supported by a bearing <NUM> provided for the inner walls <NUM> of the housing <NUM>. The protruding portion <NUM> protrudes from the back surface (inside surface) of the surface portion <NUM> toward the coupling shaft <NUM> and has a cylindrical shape. A helical spring <NUM> is wound around the outer periphery of the protruding portion <NUM>. The spring <NUM> is arranged between the surface portion <NUM> and the inner walls <NUM> while housing the protruding portion <NUM> inside. The hook <NUM> protrudes backward from a rear end, facing the coupling shaft <NUM>, of the base portion <NUM> and has the shape of a hook. A tip <NUM> (i.e., either a lower end or an upper end) of the hook <NUM> is engaged with the recess <NUM> of the hammer case <NUM>, thus allowing the pawl <NUM> to fix the housing <NUM> of the attachment <NUM> to the impact rotary tool <NUM>. The pawl <NUM> presses the recess <NUM> of the hammer case <NUM> toward the coupling shaft <NUM> with the elastic force applied by the spring <NUM>.

The pawl <NUM> further includes an operating member <NUM>. When the user of the impact rotary tool <NUM> applies force to the operating member <NUM> such that the force is transmitted toward the coupling shaft <NUM> against the elastic force applied by the spring <NUM>, the hook <NUM> moves outward (i.e., away from the coupling shaft <NUM>) around the shaft portion <NUM>. In other words, when the user applies force to the operating member <NUM> against the elastic force applied by the spring <NUM>, the tip <NUM> of the hook <NUM> may be brought out of engagement with the recess <NUM>. That is to say, the pawl <NUM> is displaced by the elastic force applied by the spring <NUM> from a position where the pawl <NUM> is engaged with the recess <NUM> to a position where the pawl <NUM> is disengaged from the recess <NUM>, and vice versa.

The input shaft <NUM> is arranged forward of the coupling shaft <NUM> such that the center axis of the input shaft <NUM> substantially agrees with the center axis of the coupling shaft <NUM>. As described above, the input shaft <NUM> and the coupling shaft <NUM> are driven integrally with each other and the rotational driving force is transmitted to the input shaft <NUM> from the coupling shaft <NUM>. The input shaft <NUM> is supported rotatably by a bearing <NUM> fixed on two inner walls <NUM> of the housing <NUM>.

The driving force conversion mechanism <NUM> includes a first gear <NUM> provided on the outer periphery of the input shaft <NUM> and a second gear <NUM> provided on the outer periphery of the second output shaft <NUM>. The first gear <NUM> and the input shaft <NUM> are driven integrally with each other. In addition, the second gear <NUM> and the second output shaft <NUM> are also driven integrally with each other. In addition, as shown in <FIG>, the driving force conversion mechanism <NUM> further includes a third gear <NUM> located in the upward/downward direction between the first gear <NUM> and the second gear <NUM>. The third gear <NUM> has a shaft <NUM> parallel to the input shaft <NUM> and the second output shaft <NUM>. Each of the first gear <NUM>, the second gear <NUM>, and the third gear <NUM> is a spur gear with a plurality of teeth protruding in the radial direction. The first gear <NUM> and the third gear <NUM> mesh with each other. The third gear <NUM> and the second gear <NUM> mesh with each other.

The driving force conversion mechanism <NUM> further includes a pair of supporting plates <NUM>. The pair of supporting plates <NUM> is located forward of the tip (front end) of the coupling shaft <NUM>. The pair of supporting plates <NUM> are provided at an interval larger than the axial length of any of the first gear <NUM>, the second gear <NUM>, or the third gear <NUM> as measured in the forward/backward direction. The pair of supporting plates <NUM> rotatably supports the input shaft <NUM>, the shaft <NUM> of the third gear <NUM>, and the second output shaft <NUM>.

When the rotational driving force is transmitted to the input shaft <NUM>, the input shaft <NUM> and the first gear <NUM> turn integrally with each other. The first gear <NUM> and the third gear <NUM> mesh with each other. Thus, as the first gear <NUM> turns, the rotational driving force is transmitted from the first gear <NUM> to the third gear <NUM>. The third gear <NUM>, to which the rotational driving force has been transmitted from the first gear <NUM>, turns in the opposite direction from the direction in which the first gear <NUM> turns. In addition, the third gear <NUM> and the second gear <NUM> also mesh with each other. Thus, as the third gear <NUM> turns, the rotational driving force is transmitted from the third gear <NUM> to the second gear <NUM>. The second gear <NUM>, to which the rotational driving force has been transmitted from the third gear <NUM>, turns in the opposite direction from the direction in which the third gear <NUM> turns. That is to say, the second gear <NUM> turns in the same direction as the first gear <NUM>. The third gear <NUM> and the second output shaft <NUM> are driven integrally with each other. Thus, the rotational driving force transmitted to the third gear <NUM> is transmitted to the second output shaft <NUM>.

As described above, the driving force conversion mechanism <NUM> according to this embodiment transmits the rotational driving force from the first gear <NUM> to the second gear <NUM> indirectly via the third gear <NUM>. The rotational axis Ax1 of the input shaft <NUM> and the rotational axis Ax2 of the second output shaft <NUM> are generally parallel to each other. That is to say, the driving force conversion mechanism <NUM> according to this embodiment translates the rotational axis Ax0 of the rotation produced by the rotational driving force when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>. Specifically, the driving force conversion mechanism <NUM> according to this embodiment translates the rotational axis Ax0 of the rotation produced by the rotational driving force from the rotational axis Ax1 of the input shaft <NUM> to the rotational axis Ax2 of the second output shaft <NUM>.

The second output shaft <NUM> is supported rotatably by a bearing <NUM> fixed on the housing <NUM> as shown in <FIG>. The second output shaft <NUM> is generally parallel to the input shaft <NUM> and arranged beside the input shaft <NUM> in the upward/downward direction and the rightward/leftward direction (i.e., directions perpendicular to the direction aligned with the input shaft <NUM>). The second output shaft <NUM> has an insert hole <NUM> and a fixing mechanism <NUM>. A tip tool such as a screwdriver bit is attached into the insert hole <NUM>. If a screwdriver bit is attached to the second output shaft <NUM>, as the second output shaft <NUM> rotates, the screwdriver bit also rotates along with the second output shaft <NUM>. Causing the screwdriver bit to rotate with the screwdriver bit kept in contact with a fastener (such as a screw) allows a type of machining work such as fastening or loosening the fastener to be done.

The fixing mechanism <NUM> includes a plurality of (e.g., two in the example illustrated in <FIG>) holes <NUM>, a plurality of (e.g., two in the example illustrated in <FIG>) steel balls <NUM>, a spring <NUM>, a bit holder <NUM>, and another spring <NUM>. The two holes <NUM> are respectively provided at upper and lower ends of the insert hole <NUM> so as to be located forward of the tip of the housing <NUM>. Each of the two holes <NUM> is a hole with the shape of an ellipse, of which the major axis is aligned with the forward/backward direction. The two steel balls <NUM> are respectively fitted into the two holes <NUM>. The bit holder <NUM> has the shape of a cylinder, of which the front and rear surfaces are open, and covers the outer periphery of the second output shaft <NUM> in a region forward of the tip of the housing <NUM>. The spring <NUM> is a helical spring covering the outer periphery of the second output shaft <NUM> between the second output shaft <NUM> and bit holder <NUM>. When a tip tool is inserted into the insert hole <NUM>, the tip tool pushes the two steel balls <NUM> obliquely upward and obliquely downward, respectively, by overcoming the elastic force of the spring <NUM>. In a state where the tip tool is inserted into the insert hole <NUM>, the two steel balls <NUM> are allowed to clamp the tip tool between themselves in the upward/downward direction by the elastic force of the spring <NUM>. If the tip tool is provided with a groove to receive the steel balls <NUM>, then the steel balls <NUM> are fitted into the groove of the tip tool, thereby fixing the tip tool with respect to the attachment <NUM>. The spring <NUM> is a helical spring which is located forward of the spring <NUM> and covers the outer periphery of the second output shaft <NUM> between the second output shaft <NUM> and the bit holder <NUM>. Causing the bit holder <NUM> to move forward against the elastic force applied by the spring <NUM> leaves a space between the bit holder <NUM> and the spring <NUM> in the upward/downward direction between the two holes <NUM>. The steel balls <NUM> fitted into the groove of the tip tool may be removed from the groove by making the two steel balls <NUM> move into the space.

The load torque of the second output shaft <NUM> is transmitted to the first output shaft <NUM> via the second gear <NUM>, the third gear <NUM>, the first gear <NUM>, the input shaft <NUM>, and the coupling shaft <NUM>. As described above, when the load torque of the first output shaft <NUM> exceeds a predetermined level, the impact mechanism <NUM> applies impacting force in the rotational direction to the first output shaft <NUM>. This impacting force in the rotational direction, as well as the rotational driving force, is transmitted to the second output shaft <NUM> via the coupling shaft <NUM>, the input shaft <NUM>, the first gear <NUM>, the third gear <NUM>, and the second gear <NUM>. This allows the second output shaft <NUM> (of the attachment <NUM>) to apply a greater fastening torque to the workpiece such as a fastener.

As described above, the tool system <NUM> according to this embodiment includes the impact rotary tool <NUM> and the attachment <NUM>. The attachment <NUM> includes the input shaft <NUM>, the second output shaft <NUM>, and the driving force conversion mechanism <NUM> for transmitting the rotational driving force transmitted from the first output shaft <NUM> of the impact rotary tool <NUM> from the input shaft <NUM> to the second output shaft <NUM>. The rotational axis Ax1 of the input shaft <NUM> and the rotational axis Ax2 of the second output shaft <NUM> are generally parallel to each other and are not aligned with each other. Thus, the driving force conversion mechanism <NUM> translates the rotational axis Ax0 of the rotation produced by the rotational driving force. By attaching the attachment <NUM> for translating the rotational axis Ax0 of the rotation produced by the rotational driving force to the impact rotary tool <NUM>, the tool system <NUM> according to this embodiment allows the user to have even a type of machining work, which has been troublesome to do with a known impact rotary tool, done easily.

In addition, the attachment <NUM> according to this embodiment further includes the housing <NUM> for housing the driving force conversion mechanism <NUM> at least partially and the attachment mechanism <NUM> for attaching and fixing the housing <NUM> onto the tip portion <NUM> of the impact rotary tool <NUM>. The housing <NUM> is fixed to the tip portion <NUM> of the impact rotary tool <NUM>, which is positioned relatively close to the attachment <NUM>. This may reduce the vibrations of the attachment <NUM> with respect to the impact rotary tool <NUM>. In addition, this may reduce the vibrations of the attachment <NUM> with respect to the impact rotary tool <NUM>, thus reducing the chances of the driving force conversion by the driving force conversion mechanism <NUM> being interrupted by the vibrations.

Furthermore, the attachment mechanism <NUM> is attached to a metallic part of the impact rotary tool. Specifically, the attachment mechanism <NUM> is attached to the hammer case <NUM> (metallic case) for housing the impact mechanism <NUM> at least partially. The metallic hammer case <NUM> will not chip easily. This reduces the chances of the part, to which the attachment mechanism <NUM> is attached, chipping due to the effect of the impact, for example.

Furthermore, the attachment mechanism <NUM> according to this embodiment includes the pawls <NUM>. Each of the pawls <NUM> is engaged with the recess <NUM> of the impact rotary tool <NUM> (hammer case <NUM>). This allows the attachment <NUM> to be fixed more firmly onto the impact rotary tool <NUM>.

In addition, the pawl <NUM> according to this embodiment is engaged with the recess <NUM> with the elastic force applied by the spring <NUM>, thus allowing the attachment <NUM> to be fixed even more firmly onto the impact rotary tool <NUM>.

Furthermore, the attachment <NUM> according to this embodiment includes the coupling shaft <NUM>. The coupling shaft <NUM> couples the first output shaft <NUM> and the input shaft <NUM> to each other and drives the first output shaft <NUM> and the input shaft <NUM> integrally with each other. The coupling shaft <NUM> transmits the rotational driving force of the first output shaft <NUM> to the input shaft <NUM>. Since the rotational driving force of the first output shaft <NUM> may be transmitted indirectly to the input shaft <NUM>, the input shaft <NUM> and the first output shaft <NUM> of the impact rotary tool <NUM> may be designed more flexibly.

Moreover, the driving force conversion mechanism <NUM> according to this embodiment further includes the first gear <NUM> provided for the input shaft <NUM> and the second gear <NUM> provided for the second output shaft <NUM>. The driving force conversion mechanism <NUM> transmits the rotational driving force indirectly (i.e., via the third gear <NUM>) from the first gear <NUM> to the second gear <NUM>, thereby transmitting the rotational driving force to the second output shaft <NUM> that is arranged beside the input shaft <NUM> in the upward/downward direction and the rightward/leftward direction. That is to say, the driving force conversion mechanism <NUM> according to this embodiment translates the rotational axis Ax0 of the rotation produced by the rotational driving force transmitted to the input shaft <NUM>. This allows, even when the workpiece such as a fastener is located at a local position, a great fastening torque to be obtained with little pressing force, thus facilitating having the machining work done.

Next, variations of the first embodiment will be enumerated one after another. Note that any of the variations to be described below may be adopted as appropriate in combination with the first embodiment described above.

The driving force conversion mechanism <NUM> may be configured to not only translate the rotational axis Ax0 of the rotation produced by the rotational driving force but also change the angle defined by the rotational axis Ax0 and/or convert the rotational driving force into thrust driving force applied along the rotational axis Ax0.

Optionally, the driving force conversion mechanism <NUM> may include an additional gear, besides the third gear <NUM>, as a member to form a path for transmitting the rotational driving force from the first gear <NUM> to the second gear <NUM>. That is to say, the driving force conversion mechanism <NUM> may include four or more gears in order to transmit the rotational driving force from the input shaft <NUM> to the second output shaft <NUM>.

The driving force conversion mechanism <NUM> does not have to include the third gear <NUM> but may transmit the rotational driving force directly from the first gear <NUM> to the second gear <NUM>. In that case, the first gear <NUM> and the second gear <NUM> are arranged to mesh with each other. Note that if the rotational driving force is transmitted directly from the first gear <NUM> to the second gear <NUM>, then the direction in which the first gear <NUM> (input shaft <NUM>) turns becomes opposite from the direction in which the second gear <NUM> (second output shaft <NUM>) turns.

The attachment mechanism <NUM> does not have to include the spring <NUM>. Alternatively, the hook <NUM> may be brought into engagement with the recess <NUM> of the hammer case <NUM> so that the hook <NUM> is pressed against the recess <NUM> with the elastic force of the hook <NUM> itself, for example.

Optionally, any part other than the hammer case <NUM> (e.g., a part of the barrel <NUM> of the impact rotary tool <NUM>) may be made of a metallic material such that the attachment mechanism <NUM> may be attached thereto.

The insert hole <NUM> does not have to have a regular hexagonal shape. Alternatively, the insert hole <NUM> may also have any other regular polygonal shape such as an equilateral triangular shape or a square shape. As used herein, the "regular polygonal shape" refers to not only a "regular polygon" in a strict sense, of which all sides have the same length and all interior angles are equal to each other, but also a shape which is similar to, and may be regarded as, a regular polygon. Still alternatively, the insert hole <NUM> may also have a circular or elliptical shape.

The input part <NUM> does not have to have the shape of a regular hexagonal prism. Alternatively, the input part <NUM> may also have the shape of any other regular polygonal prism such as an equilateral triangular prism or a square prism. As used herein, the "regular polygonal prism shape" refers to not only a "regular polygonal prism" in a strict sense, of which the bottom and upper surfaces are the same regular polygon, all sides, each connecting a pair of corresponding vertices of the bottom and upper surfaces, have the same length, and all sides, bottom surface, and upper surface intersect with each other at right angles, but also a shape which is similar to, and may be regarded as, a regular polygonal prism. Still alternatively, the input part <NUM> may also have a circular columnar shape or an elliptical columnar shape.

The thinner shaft portion <NUM> of the coupling shaft <NUM> does not have to have the recesses <NUM> and the raised portions <NUM>. As shown in <FIG>, a thinner shaft portion <NUM> according to a variation has no recesses <NUM> or raised portions <NUM>. The thinner shaft portion <NUM> according to this variation has a regular hexagonal shape when viewed in plan along the axis of the coupling shaft <NUM> and has the shape of a regular hexagonal prism extending along the axis of the coupling shaft <NUM> toward the output part <NUM>. As in the first embodiment described above, the width W2 of the thinner shaft portion <NUM> as measured in the upward/downward direction is smaller than the width W3 of the output part <NUM> as measured in the upward/downward direction.

Note that the thinner shaft portion <NUM> does not have to have the regular hexagonal prism shape but may also have any other regular polygonal prism shape or a circular or elliptical columnar shape. The thinner shaft portion <NUM> has any arbitrary shape as long as the width W2 thereof as measured in a direction in which the thinner shaft portion <NUM> faces the steel balls <NUM> is smaller than the width W3 of the output part <NUM> as measured in the same direction.

Likewise, the output part <NUM> does not have to have the regular hexagonal prism shape but may also have any other regular polygonal prism shape or a circular or elliptical columnar shape.

In the first embodiment described above, the impact rotary tool <NUM> is implemented as an impact screwdriver, for example. However, this is only an example and should not be construed as limiting. Alternatively, the impact rotary tool <NUM> may also be implemented as an impact wrench, for example.

A tool system <NUM> according to a second embodiment includes, as shown in <FIG>, an attachment 7a for converting the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force to be transmitted to the input shaft <NUM> (see <FIG>), which is a major difference from the tool system <NUM> according to the first embodiment (see <FIG>). In the following description, any constituent element of this second embodiment, having the same function as a counterpart of the first embodiment described above, will be designated by the same reference numeral as that counterpart's, and description thereof will be omitted as appropriate herein.

As shown in <FIG>, the attachment 7a according to this embodiment includes the housing <NUM>, the input shaft <NUM>, the coupling shaft <NUM>, the second output shaft <NUM>, the attachment mechanism <NUM>, and a driving force conversion mechanism 9a.

The input shaft <NUM> according to this embodiment is rotatably supported by a bearing <NUM> fixed to the housing <NUM>.

The second output shaft <NUM> according to this embodiment is positioned to cross the input shaft <NUM>. Specifically, the input shaft <NUM> extends in the forward/backward direction, while the second output shaft <NUM> extends in the upward/downward direction. The second output shaft <NUM> is rotatably supported by bearings <NUM> and <NUM> fixed to the housing <NUM>.

The driving force conversion mechanism 9a according to this embodiment includes a first gear 91a provided on the outer periphery of the input shaft <NUM> and a second gear <NUM> provided on the outer periphery of the second output shaft <NUM>. The first gear 91a and the input shaft <NUM> are driven integrally with each other. The second gear 92a and the second output shaft <NUM> are driven integrally with each other.

The first gear 91a and the second gear 92a according to this embodiment are bevel gears, of which the orientations are different from each other by <NUM> degrees and which mesh with each other (see <FIG>). For example, as the input shaft <NUM> and the first gear 91a turn clockwise around the rotational axis Ax1, the second output shaft <NUM> and the second gear 92a turn clockwise around the rotational axis Ax3. The rotational axis Ax1 and the rotational axis Ax3 extend in two directions that intersect with each other at right angles.

As can be seen from the foregoing description, the driving force conversion mechanism 9a according to this embodiment changes the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>. Specifically, the driving force conversion mechanism 9a according to this embodiment changes the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force from the angle defined by the rotational axis Ax1 of the input shaft <NUM> into the angle defined by the rotational axis Ax3 of the second output shaft <NUM>. As used herein, the angle defined by the rotational axis Ax0 refers to an angle defined by the rotational axis Ax0 with respect to a certain reference axis. In this embodiment, the rotational axis Ax1 of the input shaft <NUM> is used as the reference axis.

The driving force conversion mechanism 9a according to this embodiment includes: the first gear 91a provided for the input shaft <NUM>; and the second gear 92a provided for the second output shaft <NUM>. The driving force conversion mechanism 9a transmits the rotational driving force from the first gear 91a to the second gear 92a directly, thereby transmitting the rotational driving force to the second output shaft <NUM> that intersects with the input shaft <NUM>. That is to say, the driving force conversion mechanism 9a according to this embodiment changes the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force transmitted to the input shaft <NUM>. This allows, even when the workpiece such as a fastener forms such an angle that makes it difficult to apply force thereto, a great fastening torque to be obtained with little pressing force, thus facilitating having the machining work done easily.

Next, variations of the second embodiment will be enumerated one after another. Note that any of the variations to be described below may be adopted as appropriate in combination with the first embodiment or the variation thereof described above.

The driving force conversion mechanism 9a may also be configured to not only change the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force but also translate the rotational axis Ax0 and/or convert the rotational driving force into thrust driving force applied along the rotational axis Ax0.

In the driving force conversion mechanism 9a, the first gear 91a and the second gear 92a do not have to directly mesh with each other. Alternatively, another gear or any other suitable member may be arranged between the first gear 91a and the second gear 92a such that the rotational driving force is transmitted indirectly from the first gear 91a to the second gear 92a.

A tool system <NUM> according to a third embodiment includes an attachment 7b as shown in <FIG>, which is a major difference from the tool system <NUM> according to the first embodiment. The attachment 7b according to this embodiment includes a driving force conversion mechanism 9b for converting the rotational driving force transmitted to the input shaft <NUM> into thrust driving force applied along the rotational axis Ax0. In the following description, any constituent element of this third embodiment, having the same function as a counterpart of the first embodiment described above, will be designated by the same reference numeral as that counterpart's, and description thereof will be omitted as appropriate herein.

As shown in <FIG>, the attachment 7b according to this embodiment includes the housing <NUM>, the input shaft <NUM>, the coupling shaft <NUM>, a second output shaft 73b, the attachment mechanism <NUM> (see, for example, <FIG>), a driving force conversion mechanism 9b, a moving blade <NUM>, and a fixed blade <NUM>.

The second output shaft 73b according to this embodiment has a longitudinal axis extending in a direction aligned with the rotational axis Ax1 of the input shaft <NUM>. The second output shaft 73b and the input shaft <NUM> are aligned with the rotational axis Ax0 of the rotation produced by the rotational driving force. The second output shaft 73b has the shape of a cylinder having an opening at the rear end thereof and a closed bottom at the front end (tip) thereof. The second output shaft 73b is arranged outside of the outer periphery of the input shaft <NUM> such that the inner periphery thereof covers the input shaft <NUM>. In addition, the second output shaft 73b is supported by the housing <NUM> so as not to rotate.

The driving force conversion mechanism 9b according to this embodiment includes a first thread portion <NUM> and a second thread portion <NUM>. The first thread portion <NUM> is provided on the outer periphery of the input shaft <NUM>. The second thread portion <NUM> is provided on the inner periphery of the second output shaft 73b and screwed into the first thread portion <NUM>. As the input shaft <NUM> rotates, the first thread portion <NUM> and the input shaft <NUM> rotate integrally with each other. As the first thread portion <NUM> rotates while being engaged with the second thread portion <NUM>, thrust driving force is applied in the forward/backward direction to the second thread portion <NUM>. That is to say, the driving force conversion mechanism 9b according to this embodiment converts the rotational driving force transmitted to the input shaft <NUM> into thrust driving force applied along the rotational axis Ax0 of the rotation produced by the rotational driving force and transmits the thrust driving force to the second thread portion <NUM> (the second output shaft 73b).

The direction of the thrust driving force transmitted in the forward/backward direction to the second thread portion <NUM> varies according to the rotational direction of the first thread portion <NUM>. For example, if the first thread portion <NUM> rotates clockwise around the rotational axis Ax0, forward thrust driving force is transmitted to the second thread portion <NUM>. When the forward thrust driving force is transmitted to the second thread portion <NUM>, the second output shaft 73b moves forward within its movable range. On the other hand, if the first thread portion <NUM> rotates counterclockwise around the rotational axis Ax0, backward thrust driving force is transmitted to the second thread portion <NUM>. When the backward thrust driving force is transmitted to the second thread portion <NUM>, the second output shaft 73b moves backward within its movable range.

As can be seen from the foregoing description, the driving force conversion mechanism 9b according to this embodiment converts, when transmitting rotational driving force from the input shaft <NUM> to the second output shaft <NUM>, the rotational driving force into thrust driving force applied along the rotational axis Ax0.

The moving blade <NUM> is a blade moving along with the second output shaft 73b. That is to say, as the second output shaft 73b moves forward, the moving blade <NUM> moves forward, too. As the second output shaft 73b moves backward, the moving blade <NUM> moves backward, too. The fixed blade <NUM> is a blade fixed to the housing <NUM>. A position of the moving blade <NUM> where the workpiece T1 of cutting may be arranged between the moving blade <NUM> and the fixed blade <NUM> as shown in <FIG> will be hereinafter referred to as a "first position. " On the other hand, a position of the moving blade <NUM> where the moving blade <NUM> and the fixed blade <NUM> overlap with each other in a direction perpendicular to the rotational axis Ax1 of the input shaft <NUM> as shown in <FIG> will be hereinafter referred to as a "second position. " While the moving blade <NUM> is being displaced from the first position to the second position with the rotational driving force transmitted to the input shaft <NUM>, the workpiece T1 of cutting is cut off by the moving blade <NUM> and the fixed blade <NUM>.

The driving force conversion mechanism 9b according to this embodiment includes: a first thread portion <NUM> provided for the input shaft <NUM>; and a second thread portion <NUM> provided for the second output shaft <NUM> and screwed into the first thread portion <NUM>. The driving force conversion mechanism 9b causes, when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>, the second thread portion <NUM> and the second output shaft 73b to move along the rotational axis Ax0 of the rotation produced by the rotational driving force by turning the first thread portion <NUM> with the rotational driving force transmitted to the input shaft <NUM>. That is to say, the driving force conversion mechanism 9b according to this embodiment converts the rotational driving force into the thrust driving force by causing the second thread portion <NUM> and the second output shaft 73b to move along the rotational axis Ax0 by turning the first thread portion <NUM>. The attachment 7b according to this embodiment converts the rotational driving force to be transmitted to the input shaft <NUM> into thrust driving force applied along the rotational axis Ax0 of the rotational driving force, thus allowing the user to have a broader variety of machining work done.

In addition, in the tool system <NUM> according to this embodiment, the load torque of the input shaft <NUM> is transmitted to the first output shaft <NUM> via the coupling shaft <NUM>. As described above, when the load torque of the first output shaft <NUM> exceeds a predetermined level, the impact mechanism <NUM> applies impacting force in the rotational direction to the first output shaft <NUM>. This impacting force in the rotational direction, as well as the rotational driving force, is transmitted to the input shaft <NUM> via the coupling shaft <NUM>, converted into thrust driving force by the driving force conversion mechanism 9b, and then transmitted to the second output shaft 73b. Thus, even when great force is required to cut off a workpiece T1, the workpiece T1 may also be cut off easily with the thrust driving force converted from the impacting force produced by the impact mechanism <NUM>.

Next, variations of the third embodiment will be enumerated one after another. Note that any of the variations to be described below may be adopted as appropriate in combination with the first embodiment or the variations thereof described above and/or the second embodiment or the variations thereof described above.

As shown in <FIG>, the attachment 7c may include a moving portion <NUM> instead of the moving blade <NUM> according to the third embodiment and a fixed portion <NUM> instead of the fixed blade <NUM> according to the third embodiment. The attachment 7c may be used as a pressure bonding attachment for bonding a pair of workpieces together with pressure by clamping the pair of workpieces between the moving portion <NUM> and the fixed portion <NUM>, for example.

The attachment 7c may function as a pressure bonding attachment by converting the rotational driving force to be transmitted to the input shaft <NUM> into thrust driving force applied along the rotational axis Ax0 of the rotational driving force. In addition, even if great force is required to bond a pair of workpieces together with pressure, the pair of workpieces may be easily pressure-bonded together with the thrust driving force converted from the impacting force produced by the impact mechanism <NUM>.

The driving force conversion mechanism 9b may be configured to not only convert the rotational driving force into thrust driving force applied along the rotational axis Ax0 of the rotation produced by the rotational driving force but also translate the rotational axis Ax0 and/or change the angle defined by the rotational axis Ax0.

As can be seen from the foregoing description, a tool system <NUM> includes an impact rotary tool attachment <NUM>; 7a; 7b; 7c and an impact rotary tool <NUM> to which the impact rotary tool attachment <NUM>; 7a; 7b; 7c is attached. The impact rotary tool attachment <NUM>; 7a; 7b; 7c includes an input shaft <NUM>, a second output shaft <NUM>, and a driving force conversion mechanism <NUM>; 9a; 9b. To the input shaft <NUM>, rotational driving force is transmitted from a first output shaft <NUM> of an impact rotary tool <NUM>. To the second output shaft <NUM>, the rotational driving force is transmitted from the input shaft <NUM>. The driving force conversion mechanism <NUM>; 9a; 9b performs, when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>, at least one operation selected from the group consisting of: translating a rotational axis Ax0 of rotation produced by the rotational driving force; changing an angle defined by the rotational axis Ax0; and converting the rotational driving force into thrust driving force applied along the rotational axis Ax0.

This allows the user to have even a type of machining work, which has been troublesome to do with a known impact rotary tool <NUM>, done more easily, because the impact rotary tool attachment <NUM>; 7a; 7b; 7c includes the driving force conversion mechanism <NUM>; 9a; 9b.

The impact rotary tool attachment <NUM>; 7a; 7b; 7c further includes a housing <NUM> and an attachment mechanism <NUM>. The housing <NUM> houses the driving force conversion mechanism <NUM>; 9a; 9b at least partially. The attachment mechanism <NUM> attaches and fixes the housing <NUM> onto a tip portion <NUM> of the impact rotary tool <NUM>.

The housing <NUM> is fixed to the tip portion <NUM> of the impact rotary tool <NUM>. The tip portion <NUM> of the impact rotary tool <NUM> may be positioned relatively close to the impact rotary tool attachment <NUM>; 7a; 7b; 7c, thus reducing the vibrations of the impact rotary tool attachment <NUM>; 7a; 7b; 7c with respect to the impact rotary tool <NUM>. In addition, reducing the vibrations of the impact rotary tool attachment <NUM>; 7a; 7b; 7c with respect to the impact rotary tool <NUM> reduces the chances of the driving force conversion by the driving force conversion mechanism <NUM>; 9a; 9b being interrupted by the vibrations.

The attachment mechanism <NUM> is attached to a metallic part hammer case <NUM> of the impact rotary tool <NUM>.

This allows the impact rotary tool attachment <NUM>; 7a; 7b; 7c to be fixed more firmly onto the impact rotary tool <NUM> because the metallic part (hammer case <NUM>) will not chip easily.

The impact rotary tool <NUM> includes: an impact mechanism <NUM>; and a metallic case hammer case <NUM>. The metallic case houses the impact mechanism <NUM> at least partially. The attachment mechanism <NUM> is attached to the metallic case.

This allows the impact rotary tool attachment <NUM>; 7a; 7b; 7c to be fixed more firmly onto the impact rotary tool <NUM> because the metallic part hammer case <NUM> will not chip easily.

The attachment mechanism <NUM> may include a pawl <NUM> to be hooked on the impact rotary tool <NUM>.

This allows the impact rotary tool attachment <NUM>; 7a; 7b; 7c to be fixed more firmly onto the impact rotary tool <NUM> because the pawl <NUM> of the impact rotary tool attachment <NUM>; 7a; 7b; 7c is hooked on the impact rotary tool <NUM>.

The pawl <NUM> may be hooked, by elastic force, on the impact rotary tool <NUM>.

This allows the impact rotary tool attachment <NUM>; 7a; 7b; 7c to be fixed more firmly onto the impact rotary tool <NUM> because the pawl <NUM> of the impact rotary tool attachment <NUM>; 7a; 7b; 7c is hooked, by elastic force, on the impact rotary tool <NUM>.

The impact rotary tool attachment <NUM>; 7a; 7b; 7c may further include a coupling shaft <NUM> to couple the first output shaft <NUM> and the input shaft <NUM> and to be driven in rotation along with the first output shaft <NUM> and the input shaft <NUM>. The coupling shaft <NUM> may transmit the rotational driving force of the first output shaft <NUM> from the first output shaft <NUM> to the input shaft <NUM>.

This allows the input shaft <NUM> and the first output shaft <NUM> to be designed more flexibly because the rotational driving force of the first output shaft <NUM> may be transmitted indirectly to the input shaft <NUM>.

A rotational axis Ax1 of the input shaft <NUM> and a rotational axis Ax2 of the second output shaft <NUM> may be arranged side by side. The driving force conversion mechanism <NUM> may include a first gear <NUM> and a second gear <NUM>. The first gear <NUM> may be provided for the input shaft <NUM>. The second gear <NUM> may be provided for the second output shaft <NUM>. The driving force conversion mechanism <NUM> may translate the rotational axis Ax0 of the rotation produced by the rotational driving force by transmitting the rotational driving force from the first gear <NUM> to the second gear <NUM> either directly or indirectly when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>.

This allows, even when the workpiece is located at a local position, a great fastening torque to be obtained with little pressing force, thus facilitating having the machining work done easily.

A rotational axis Ax1 of the input shaft <NUM> and a rotational axis Ax3 of the second output shaft <NUM> may intersect with each other. The driving force conversion mechanism 9a may include a first gear 91a and a second gear 92a. The first gear 91a may be provided for the input shaft <NUM>. The second gear 92a may be provided for the second output shaft <NUM>. The driving force conversion mechanism 9a may change the angle defined by the rotational axis Ax0 of the rotation produced by the rotational driving force by transmitting the rotational driving force from the first gear 91a to the second gear 92a either directly or indirectly when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>.

This allows, even when the workpiece forms such an angle that makes it difficult to apply force thereto, a great fastening torque to be obtained with little pressing force, thus facilitating having the machining work done easily.

The input shaft <NUM> and the second output shaft <NUM> may be aligned with the rotational axis Ax0 of the rotation produced by the rotational driving force. The driving force conversion mechanism 9b may include a first thread portion <NUM> and a second thread portion <NUM>. The first thread portion <NUM> may be provided for the input shaft <NUM>. The second thread portion <NUM> may be provided for the second output shaft <NUM> and screwed into the first thread portion <NUM>. The driving force conversion mechanism 9b may convert, when the rotational driving force is transmitted from the input shaft <NUM> to the second output shaft <NUM>, the rotational driving force into the thrust driving force by causing the second thread portion <NUM> and the second output shaft <NUM> to move along the rotational axis Ax0 of the rotation produced by the rotational driving force. The movement of the second thread portion <NUM> and the second output shaft <NUM> may be caused when rotation of the first thread portion <NUM> is produced by the rotational driving force transmitted to the input shaft <NUM>.

This allows the user to have various types of machining work done easily by converting the rotational driving force to be transmitted to the input shaft <NUM> into thrust driving force applied along the rotational axis Ax0 of the rotational driving force.

Claim 1:
A tool system (<NUM>) comprising:
an impact rotary tool attachment (<NUM>; 7a; 7b; 7c); and
an impact rotary tool (<NUM>) to which the impact rotary tool attachment (<NUM>; 7a; 7b; 7c) is attached, wherein
the impact rotary tool attachment (<NUM>; 7a; 7b; 7c) includes:
an input shaft (<NUM>), to which rotational driving force is transmitted from a first output shaft (<NUM>) of the impact rotary tool (<NUM>);
a second output shaft (<NUM>), to which the rotational driving force is transmitted from the input shaft (<NUM>);
a driving force conversion mechanism (<NUM>; 9a; 9b) configured to, when the rotational driving force is transmitted from the input shaft (<NUM>) to the second output shaft (<NUM>), perform at least one operation selected from the group consisting of: translating a rotational axis (Ax0) of rotation produced by the rotational driving force; changing an angle defined by the rotational axis (Ax0); and converting the rotational driving force into thrust driving force applied along the rotational axis (Ax0):
a housing (<NUM>) to house the driving force conversion mechanism (<NUM>; 9a; 9b) at least partially; and
an attachment mechanism (<NUM>) configured to attach and fix the housing (<NUM>) onto a tip portion (<NUM>) of the impact rotary tool (<NUM>), and
the impact rotary tool (<NUM>) including:
an impact mechanism (<NUM>); and
a metallic case (<NUM>) to house the impact mechanism (<NUM>) at least partially, and
the attachment mechanism (<NUM>) being attached to the metallic case (<NUM>), and
the impact mechanism (<NUM>) including an anvil (<NUM>) and a hammer (<NUM>) configured to apply rotational impact to the anvil (<NUM>).