1.  Field of the Invention
The present invention relates to a power tool having a hook potion that is hookable onto a waist belt of an operator. 
2.  Description of the Related Art
A conventional power tool has a hook portion for hooking the power tool onto a waist belt of an operator.  When this hook portion is fixedly placed in a state in which the hook portion projects from, for example, a power tool body, the hook portion comes in contact with peripheral members during an operation.  Especially, when an operation is performed in a narrow place, the hook portion hinders an operator from performing an operation.  Thus, the conventional power tool has a problem in that the workability is lowered.  Further, because the hook portion is an obstacle to an operation, a certain conventional power tool is adapted so that the hook portion is detached therefrom as needs arise.  However, such a conventional power tool has encountered a problem in that the hook portion is missing.  Thus, another conventional power tool is adapted so that when the hook portion is unnecessary, the hook portion is accommodated therein or moved to a position, at which the hook portion is not a hindrance to an operation. 
An example of the aforementioned hook portion is described hereinbelow by referring to FIG.  17.  This hook portion comprises a hook 4 formed by coating the entire perimeter of a catching piece 2, which is formed by bending a threaded bar-like iron material, with a soft material 3, and also comprises a holding nut 5 for holding the hook 4, and a slip-off preventing nut (not shown), which is provided in the housing 1, for preventing the hook 4 from slipping off the power tool.  The catching piece 2 of this hook portion can be turned from an accommodating position, which is almost adjacent to a battery 18, to a gap formed between the catching piece 2b and a handle 9, as indicated by a two-dot dashed line.  Moreover, at the position of this gap, the catching piece 2 projects therefrom in such a way as to be able to be caught therein.  Furthermore, stability is obtained by hooking the catching piece to the belt when the hook 4 is in a state in which a tip end thereof is directed to the center of gravity of the power tool.  Thus, even when a continuous screw attachment 7 is removed from a power tool body, so that the position of the center of gravity of the power tool is changed, the power tool is adjusted to a stable position by turning the catching piece 2b.  Furthermore, it is often that the catching piece 2 of the hook 4 projects most sideways from the handle 9.  Therefore, even when the power tool is put on the slope of a tilted roof, the soft material 3, with which the hook 4 is coated, provides antislipping action.  Moreover, when the power tool is put on a member, such as a decorative panel, the soft material 3 also provides protecting action in such a way as to prevent the member from being damaged. 
Further, a certain conventional power tool is adapted so that the entire hook of a hook portion having been projected from and fixed to a power tool body is slidably accommodated in a concave portion provided in the power tool body, as disclosed in JP-A-2000-167785. 
Moreover, differently from the conventional hook of the accommodating type, another example of a conventional hook is adapted in such a way as to be able to turn around the outer periphery of a nearly-cylindrical motor housing of a power tool and to be positioned at a plurality of places by catching a hook portion, as disclosed in JP-A-6-285774. 
Furthermore, another conventional power tool has a hook portion of the turning type having a convex or concave portion, which can be fitted into a left-side surface of a motor housing having a convex or concave portion, and a hook is detachably attached to this hook portion with a single motion, as disclosed in JP-A-9-225861. 
On the other hand, a tip end of the tip tool, such as the bit, is liable to damage in a screwing operation.  Thus, it is necessary to exchange the bit.  However, it is trouble some that a bit attached to the power tool used during high-place work performed on a stepladder and a scaffold is replaced with another bit put on the ground.  Further, in the case that a replacement bit is put into a pocket, there is high possibility that the replacement bit is dropped and lost when, for instance, screws are taken out of the pocket.  Thus, there is provided a conventional power tool adapted so that a replacement bit is accommodated in a housing, as disclosed in JP-A-9-216171.  A bit accommodating portion of this power tool is formed in a battery receiving portion provided in a lower portion of a handle so that ribs are provided on both side surfaces thereof around a bit so as to prevent the bit from being caught in clothes and dropped, and that the bit is almost completely embedded therein.  Additionally, a metal latch fitting is provided in this bit accommodating portion in such a way as to pressure-attach and hold the bit at a single place.  Thus, when the bit is taken out, the metal latch fitting is bent and drawn out in the radial direction of the axis of the bit. 
The hook portion shown in FIG.  17 has encountered a problem that each time when the catching piece is turned for accommodation, pullout, and adjustment thereof, it is necessary and troublesome to perform an operation of rotating a holding nut by using a tool, such as a spanner. 
Further, although the hook portion disclosed in JP-A-2000-167785 is stable and constructed so that the pullout and accommodation of the hook are easily performed, an accommodating portion in which a hook is accommodated, a guide portion in which the hook can slide, and a supporting portion for supporting the hook should be embedded therein.  Thus, this conventional hook portion has encountered a problem that the size of the power tool increases. 
Moreover, the conventional hook portion disclosed in JP-A-6-285774 is constructed so that the hook is turned around a nearly cylindrical motor housing of the power tool, and that the hook is projected therefrom in such a way as to provide a uniform gap between the hook and the outer periphery of the motor housing.  However, this hook portion uses a leaf spring for elastically catching the gear provided on the hook.  Thus, this conventional hook portion has encountered a problem that when a force is applied in the turning direction of the hook, the hook is easily rotated and unstable.  Furthermore, this conventional hook portion has encountered another problem that when the hook is locked by a manually-operated lock knob, an operator needs to turn the hook by using one hand during the lock state is canceled by using the other hand, and that thus the operability thereof is poor. 
Furthermore, in the case of the hook portion disclosed in JP-A-9-225861, the position, at which the hook is mounted, is changed so that a narrow object to be hooked is caught in the gap formed between the hook and the motor housing.  On the other hand, a wide object to be hooked is caught in the gap formed between the hook and the handle.  However, the position of the turned hook is held by an elastic locking force applied between the materials.  Thus, this conventional hook portion has encountered a problem that when a force is applied to the hook in the turning direction, the hook is easily turned and thus has poor stability.  Moreover, although the holding portion enabled to be detached by performing a one-touch operation is provided on the left-side surface of the motor housing, it is necessary for enhancing the operability thereof for both a right-handed person and a left-handed person to provide the holding portion on the right-side surface thereof.  In this case, this hook portion has encountered another problem in that the holding portion provided at the side, at which no hook is attached, hinders the operation. 
On the other hand, the conventional power tool comprises a motor housing containing a motor and a gear, handle, battery, a battery receiving portion, and a bit accommodating portion, as disclosed in JP-A-9-216171.  Consideration is given hereinbelow to the place at the bit accommodating portion is provided.  The motor housing has no space, in which the bit is embedded, and is slid into a narrow space, in which a screwing operation is performed, so that the motor housing is unsuitable for being provided in such a way as to project from the tool body.  When provided in the handle, the bit accommodating portion becomes hard to grasp.  When provided in the battery, the versatility of the battery is lowered.  The battery receiving portion has no space in which the bit accommodating portion is embedded.  Therefore, it is preferable that the bit accommodating portion is provided in the battery receiving portion in such a way as to protrude therefrom.  However, this conventional power tool has encountered a problem that when the hook shown in, for example, FIG.  17 is provided in such a power tool, a pull-out piece (see FIG.  17) of the hook hits and is in the way of accessing the bit accommodating portion.  Moreover, this conventional power tool has encountered another problem that even when the pull-out piece (see FIG.  17) is provided at the side of the bit accommodating portion, a portable tool is not compact and thus, the efficiency in space utilization is poor.  Furthermore, when the metal latch fitting disclosed in JP-A-9-216171 is used, the cost and time needed for assembling the fitting to the tool are high.  Thus, preferably, the latch fitting is resin-molded in such a way as to be integral with the housing.  However, this conventional power tool has encountered a problem that when the metal latch fitting is simply replaced with a resin-molded latch fitting, the strength of the resin is lower than that of the iron and that it is thus necessary to increase the thickness of a resin layer to the extent that the fitting can hold the bit.  Conversely, it is necessary to reduce the thickness thereof so that the bit can be removed by bending the metal latch fitting.  Thus, this conventional power tool has encountered another problem that such contradictory necessities for setting the thickness of the resin fitting arise.  Additionally, the entire periphery of the catching piece is covered with a cap-like member made of a soft material in the example of a portable tool having the hook coated with the soft material as shown in FIG.  17.  However, when the bit accommodating portion disclosed in, for instance, JP-A-9-216171 is provided in the catching piece, this conventional power tool has encountered another problem that the bit is covered with the soft material and thus disabled to be detached therefrom, and that even when a part of the soft material is cut out, a the bit accommodating portion is cracked from the place at which the soft material is cut by performing an assembling operation or by wear.