Elongated-member-driving apparatus – With means to move or guide member into driving position – Including supply magazine for constantly urged members
Reexamination Certificate
2003-05-29
2004-08-31
Smith, Scott A. (Department: 3721)
Elongated-member-driving apparatus
With means to move or guide member into driving position
Including supply magazine for constantly urged members
C227S156000
Reexamination Certificate
active
06783050
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a nail gun provided with an air duster which ejects compressed air for removing dust, wood chips and wood shavings out of an intended nail driving area.
Laid open Japanese Patent Application publication No. Hei 10-109280 discloses, as shown in
FIGS. 1 and 2
, a nail gun
601
having nail driving function A and duster function B. The nail gun
601
includes a main housing
602
and a handle
602
A. In the main housing
602
a compressed air chamber
603
is provided, and a cylinder, a piston and a driver blade are disposed. The piston is reciprocally movable in the cylinder by pneumatic pressure applied in the compressed air chamber
603
through a hose
602
B, and the driver blade extends from the piston for driving a head of a nail. A safety arm
611
is axially movably provided at a lower portion of the main housing
602
. The safety arm
611
has a tip end abuttable on a workpiece. A magazine
620
is also provided at the lower portion of the main housing
602
for accommodating therein nails. A trigger lever
610
is provided near the handle
602
A and cooperated with the safety arm
611
for driving the nail into the workpiece upon pulling the trigger lever
610
by the pneumatic pressure applied to the piston from the compressed air chamber
603
after depressing the safety lever
611
onto the workpiece.
An exhaust cover
621
is provided at an upper end of the main housing
602
, and an duster nozzle
624
is provided in the exhaust cover
621
. The duster nozzle
624
has a nozzle opening with a reduced diameter. A pressure release valve
622
is provided in the exhaust cover
621
for selectively communicating the compressed air chamber
603
with the duster nozzle
624
through first and second air passages
625
and
626
. The pressure release valve
622
is connected to an operation button
623
positioned near the handle
602
A, so that an operator can push the operation button
623
by a finger while gripping the handle
602
A with remaining fingers of the same hand. For cleaning a surface of the workpiece before nail driving operation, the duster nozzle
624
is directed toward the surface and the operation button
623
is depressed. As a result, a compressed air in the compressed air chamber
603
is ejected out of the duster nozzle
624
to remove the dust, wood chips and wood shavings.
FIG. 2
shows a detail of the pressure release valve
622
. The compressed air chamber
603
is communicated with the pressure release valve
622
through the first air passage
625
, and the pressure release valve
622
is communicated with the duster nozzle
624
through the second air passage
626
. The pressure release valve
622
includes a valve stem
622
A axially movable within a valve bush
629
. An O-ring
627
is disposed over the valve stem
622
A for constantly shutting off air communication between atmosphere and the second air passage
626
. Another O-ring
628
is disposed over the valve stem
622
A and is seatable on a valve seat section of the valve stem
622
A for shutting off air communication between the first and second air passages
625
and
626
when the operation button
623
is not manipulated, and for communicating the first air passage
625
with the second air passage
626
when the operation button is depressed. The O-ring
628
and the valve bush
629
provide a first cylindrical sealing area with a diameter C, and the O-ring
627
and the valve bush
629
provide a second cylindrical sealing area with a diameter D which is smaller than the diameter C. The O-ring
628
defines a pressure release valve chamber
631
in which a compression spring
630
is interposed between an end wall of the valve chamber
631
and an inner end of the valve stem
622
A. The valve stem
622
A is biased toward the operation button
623
by the biasing force of the compression spring
630
and the pneumatic pressure in the compressed air chamber
603
.
For driving the nail, the pneumatic pressure ranging from 0.98 to 2.45 Mpa is required, whereas for duster function the required pneumatic pressure is in a range of from 0.39 to 0.83 Mpa, which is lower than the nail driving pressure. Here, compressed air in the compressed air chamber
603
serves as a power source for driving the nail as well as for ejecting air through the duster nozzle
624
. Therefore, the duster pressure must be the same as the nail driving pressure. Because the nail driving pressure cannot be lowered, the duster pressure is undesirably high. When the excessively high pressure is ejected from the nozzle
624
, the air can raise up a cloud of dust around the user, or the nail gun
601
can move around uncontrollably due to reaction force, or loud ejection noise may be generated. If the inner diameter of the nozzle opening of the duster nozzle
624
is reduced in an attempt to reduce the pressure level of the ejected air, treble sound is generated at the nozzle opening, or the first O-ring
628
may be disengaged from an annular O-ring groove formed in the outer peripheral surface of the valve stem
622
A due to application of high pressure to the first O-ring
628
from the compressed air chamber
603
.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the above-described problems and to provide an improved nail gun having a duster function providing a pressure level of air ejected out of the duster nozzle sufficiently lower than that of the compressed air chamber.
Another object of the invention is to provide such nail gun capable of lowering ejection sound at the duster nozzle and maintaining the O-ring at its given position without disengagement from the associated O-ring groove.
These and other objects of the present invention will be attained by a pneumatically operated nail gun including a main body defining therein a compressed air chamber, a cylinder, a piston, a driver blade, a control valve, and an improved duster mechanism. The cylinder is fixedly disposed in the main body and provides a cylinder space. The piston is slidably movable in the cylinder between its upper dead center and a lower dead center and divides the cylinder space into an upper cylinder space and a lower cylinder space. The driver blade extends from the piston in the lower cylinder space and is protrudable from a lower end of the main body for striking against a head of the nail in accordance with the movement of the piston toward its lower dead center. The control valve is supported to the main body and selectively introduces a compressed air into the upper cylinder space from the compressed air chamber and discharges the compressed air in the upper cylinder space to an atmosphere. The duster mechanism includes a duster nozzle, an air passage section, a pressure release valve, and a pressure reducing section. The duster nozzle is provided at the main body for ejecting a compressed air therethrough. The air passage section extends between the duster nozzle and the compressed air chamber. The pressure release valve is disposed at the air passage section for selectively shutting off a fluid communication between the compressed air chamber and the duster nozzle. The pressure reducing section is disposed at the air passage section for providing a compressed air passing through the duster nozzle at a pressure lower than that in the compressed air chamber.
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patent: 3905535 (1975-09-01), Novak et al.
patent: 4039113 (1977-08-01), Males
patent: 4384668 (1983-05-01), Tutomu et al.
patent: 4736879 (1988-04-01), Yamada et al.
patent: 5259465 (1993-11-01), Mukoyama
patent: 5715986 (1998-02-01), Sauer
patent: 5829660 (1998-11-01), White
patent: 5850961 (1998-12-01), Braun et al.
patent: 5878936 (1999-03-01), Adachi et al.
patent: 5918788 (1999-07-01), Moorman et al.
patent: 6572000 (2003-06-01), Hirai et al.
Ishizawa Yoshinori
Nakano Yoshihiro
Hitachi Koki Co,. Ltd.
Sughrue & Mion, PLLC
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