Elongated-member-driving apparatus – With means to move or guide member into driving position – Including supply magazine for constantly urged members
Reexamination Certificate
2001-01-24
2004-06-08
Sipos, John (Department: 3721)
Elongated-member-driving apparatus
With means to move or guide member into driving position
Including supply magazine for constantly urged members
C227S008000
Reexamination Certificate
active
06745928
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a trigger valve apparatus preferably employed in a pneumatic tool, such as a nailar or a similar pneumatic tool.
FIG. 17
shows a conventional pneumatic fastener.
FIG. 18
shows a trigger valve apparatus employed in the pneumatic fastener shown in FIG.
17
.
A trigger valve
106
comprises a plunger
107
shiftable in an axial direction in response to a movement of a trigger
139
, and a valve piston
109
shiftable in an opposed direction in response to the shift movement of the plunger
107
. The valve piston
109
directly controls compressed air supplied to or discharged from a sleeve valve chamber
108
. The trigger valve
106
further comprises valve bushes
110
and
111
supporting the plunger
107
and the valve piston
109
so as to be slidable in the axial direction thereof. A spring
112
is interposed between the plunger
107
and the valve piston
109
.
An air passage
116
connects a valve piston chamber
113
and the atmosphere. An O-ring
125
, provided at a lower portion of the plunger
107
, selectively opens or closes the air passage
116
in accordance with a shift movement of the plunger
107
. An air passage
114
connects an accumulator chamber
102
to the valve piston chamber
113
. An O-ring
115
, provided on a cylindrical surface of an axial bore of the valve piston
109
, selectively opens or closes the air passage
114
in response to a shift movement of the plunger
107
. An air passage
120
connects the accumulator chamber
102
to the sleeve valve chamber
108
located below a sleeve valve
119
. An O-ring
121
selectively opens or closes the air passage
120
in accordance with a shift movement of the valve piston
109
. An air passage
147
connects the air passage
120
to the atmosphere. An O-ring
123
selectively opens or closes the air passage
147
in accordance with a shift movement of the valve piston
109
. An O-ring
124
, coupled around the valve piston
109
, seals a clearance between the valve piston
109
and the bush
110
. Thus, the valve piston chamber
113
is always isolated from the air passage
147
by the O-ring
124
.
When the valve piston
109
is positioned at its top dead center, the accumulator chamber
102
communicates with the sleeve valve chamber
108
while the sleeve valve chamber
108
is isolated from the atmosphere because the air passage
147
is closed by the O-ring
123
as shown in FIG.
19
. When the valve piston
109
is positioned at its bottom dead center, the sleeve valve chamber
108
communicates with the atmosphere via the air passage
147
while the sleeve valve chamber
108
is isolated from the accumulator chamber
102
by the O-ring
121
as shown in FIG.
20
.
A sleeve valve portion
126
, serving as a main valve, comprises a sleeve valve
119
, a sleeve valve rubber
127
, a sleeve valve spring
128
, an exhaust rubber
130
, and O-rings
131
and
132
. The sleeve valve rubber
127
is coupled around an upper end portion of the sleeve valve
119
so as to selectively connect or disconnect the cylinder
103
to or from the accumulator chamber
102
. The sleeve valve spring
128
resiliently urges the sleeve valve
119
toward its top dead center. An air passage
129
is provided for exhausting compressed air from an upper space of the piston
104
a
of the cylinder
103
. The exhaust rubber
130
is coupled with the upper portion of the cylinder
103
and selectively brought into contact with the sleeve valve
119
to open or close the air passage
129
. The O-rings
131
and
132
are provided to always isolate the sleeve valve chamber
108
from the air passage
129
.
When the sleeve valve
119
is lowered, the sleeve valve
119
is brought into contact with the exhaust rubber
130
to close the air passage
129
while the accumulator chamber
102
communicates with the upper space of the piston
104
a
in the cylinder
103
. When the sleeve valve
119
is raised, the upper end of the cylinder
103
is closed and the sleeve valve
119
separates from the exhaust rubber
130
to open the air passage
129
. The air passage
129
communicates with the atmosphere via an air passage (not shown).
A return air chamber
133
, provided around a lower portion of the cylinder
103
, stores compressed air to return the driver blade
104
b
to its top dead center. An air passage
135
, having a check valve
134
, is provided near an axial center of the cylinder
103
. An air passage
136
is provided at the lower portion of the cylinder
103
. A piston bumper
137
is located near the lower end of the cylinder
103
. The piston bumper
137
absorbs excessive energy of the driver blade
104
b
after the driver blade
104
b
has struck the nail
105
.
An operating portion
138
comprises a trigger
139
operated by a user, an arm plate
140
positioned between the trigger
139
and the plunger
107
, and a push lever
142
extending from the lower end of a nose
141
to the vicinity of the arm plate
140
. The push lever
142
is resiliently urged toward the nose
141
and slidable along the nose
141
. The plunger
107
is raised upward only when the trigger
139
is pulled by the user and the push lever
142
is shifted against the resilient force with the tip of the push lever
142
being pressed to a member into which the nail
105
is struck.
Hereinafter, an operation of the above-described pneumatic fastener
101
will be explained with reference to
FIGS. 17 through 21
.
FIGS. 17 and 18
show the pneumatic fastener
101
and the trigger valve
106
in a condition where the accumulator chamber
102
is filled with compressed air. Part of the compressed air stored in the accumulator chamber
102
flows into the valve piston chamber
113
via the air passage
114
. The plunger
107
is positioned at its bottom dead center as it receives a differential force caused by a diameter difference between the O-ring
115
and the O-ring
125
as well as a resilient force of the spring
112
. Furthermore, part of the compressed air stored in the accumulator chamber
102
flows into the sleeve valve chamber
108
via the air passage
120
. The sleeve valve
119
is positioned at its top dead center as it receives a differential force caused by a diameter difference between the sleeve valve rubber
127
and an O-ring
146
as well as another differential force caused by a diameter difference between the O-ring
131
and the O-ring
132
in addition to a resilient force of the sleeve valve spring
128
.
FIG. 19
shows a condition of the trigger valve
106
at a moment where the plunger
107
is positioned at its top dead center. The O-ring
115
closes the air passage
114
. The valve piston chamber
113
communicates with the atmosphere via the air passage
116
. So, the compressed air can go out of the valve piston chamber
113
.
FIG. 20
shows a condition of the trigger valve
106
at a moment where the valve piston
109
has moved at its bottom dead center in response to the shift movement of the plunger
107
to its top dead center.
When the pressure in valve piston chamber
113
is substantially equalized with the atmospheric pressure, the valve piston
109
receives a differential force caused by a diameter difference between the O-ring
121
and the O-ring
124
and therefore shifts to its bottom dead center against the resilient force of the spring
112
. The O-ring
121
closes the air passage
120
. The sleeve valve chamber
108
communicates with the atmosphere via the air passages
120
and
147
. The compressed air is exhausted from the sleeve valve chamber
108
.
When the pressure in the sleeve valve chamber
108
is substantially equalized with the atmospheric pressure, the sleeve valve
119
receives a differential force caused by a diameter difference between the sleeve valve rubber
127
and the O-ring
146
and therefore starts shifting toward its bottom dead center against the resilient force of the sleeve valve spring
128
. When the accumulator chamber
102
communicates with the cylinder
103
, the sleeve valve
119
recei
Aoki Masanori
Ishizawa Yoshinori
Kitagawa Hiroki
Connolly Bove & Lodge & Hutz LLP
Hitachi Co., Ltd
Sipos John
Tran Louis
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