Abstract
A switch mechanism for a pneumatic tool comprises a choke ring having
an air hole disposed in an air passage of the pneumatic tool; A control
rod is swayably inserted through the air hole with a first end of
corresponds to a trigger of the pneumatic tool; A choke member is
provided for insertion of a second end of the control rod and pushed
by a spring to seal the choke ring. A bushing is disposed in an air
passage and located between the choke member and the inner wall of
the air passage of the base body and between the choke member and
the choke ring. By such arrangement, the inner wall of the air passage
of the base body and the choke ring can be avoided from being abraded
by the choke member.
Claims
1. A switch mechanism for a pneumatic tool comprising: a choke ring
disposed in an air passage of a pneumatic tool, at a center of the
choke ring formed with an air hole; a control rod swayably inserted
through the air hole of the choke ring, and a first end of the control
rod corresponds to a trigger of the pneumatic tool; a choke member
provided for insertion of a second end of the control rod, the choke
member pushed by a spring so that the choke ring is sealed by an end
surface of the choke member; wherein a bushing is provided in the
air passage of the base body and located between the choke member
and inner wall of the air passage of the base body, and between the
choke member and the choke ring, so as to prevent the inner wall of
the air passage of the base body and the choke ring from being worn
or abraded by the choke member.
2. The switch mechanism for a pneumatic tool as claimed in claim
1, wherein the bushing has annular abutting portion, and an annular
shoulder portion that is formed at an end surface of the annular
abutting portion, the annular abutting portion is located between
the inner wall of the air passage of the base body and used to abut
against the inner wall of the air passage of the base body, the
annular shoulder portion is located between the choke member and
the choke ring.
3. The switch mechanism for a pneumatic tool as claimed in claim
1, wherein an annular protrusion is formed about a periphery of
the air hole and abuts against inner periphery of the annular shoulder
portion of the bushing.
4. The switch mechanism for a pneumatic tool as claimed in claim
1, wherein hardness of the bushing is greater than that of the choke
member.
5. The switch mechanism for a pneumatic tool as claimed in claim
1, wherein the bushing is made of metal.
6. The switch mechanism for a pneumatic tool as claimed in claim
4, wherein the bushing is made of metal.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a pneumatic tool, and more particularly
to a switch mechanism for a pneumatic tool.
[0003] 2. Description of the Prior Arts
[0004] All pneumatic tools are equipped with a switch mechanism
that is actuated by trigger to allow the air enter the inside of
the pneumatic tool to perform pneumatic operation. The switch mechanism
is an indispensable part of the pneumatic tool, which has many different
structural forms. The motivation of the present invention is to
develop a switch mechanism that will not damage the base body of
the pneumatic tool, and part of the switch mechanism is easy to
be replaced after it is worn or broken.
[0005] As shown in FIGS. 1 and 2, a conventional switch mechanism
for a pneumatic tool generally includes a choke ring 12, a control
rod 13 and a choke member 14. The choke ring 12 is fixed in an air
passage 11 of a base body 10 of the pneumatic tool, and an air hole
121 is formed at the center of the choke ring 12. The control rod
13 is swayably inserted through the air hole 121 of the choke ring
12 with a first end of the control rod 13 corresponds to a trigger
15 of the pneumatic tool and a first end of which is inserted in
a choke member 14. The choke member 14 is provided around the outer
periphery thereof with a choke portion 141 that is pushed by a spring
16 and to seal the choke ring 12. When the pneumatic tool is in
use, the choke portion 141 of the choke member 14 is pushed by the
spring 16 to seal the air hole 121 of the choke ring 12, so that
the air in the air passage 11 of the base body 10 is unable to enter
the inside of the base boy via the air hole 121 of the choke ring
12. As shown in FIG. 3, if the user presses the trigger 15, the
control rod 13 will be pushed by the trigger 15 to sway an angle
and the choke portion 141 of the choke member 1 will disengage from
the air hole 121 of the choke ring 12. At this moment, air is allowed
to enter the base body through the air hole 121 of the choke ring
12. This conventional switch mechanism still has some disadvantages
that are explained as follows:
[0006] First, in operation, the trigger 15 pushes the control rod
13 to make it sway an angle and synchronously make the choke member
14 sway an angle too. Since there is no any component arranged between
the choke member 14 and the choke ring 12, and between the choke
member 14 and the inner wall of the air passage 11 of the base body
10. The choke portion 141 of the choke member 14 directly contacts
the choke ring 12 and the air passage 11 of the base body 10. After
a certain time of use, the choke ring 12 and the inner wall of the
air passage 11 of the base body 10 will be worn or broken due to
different hardness of the respective components.
[0007] Second, once the choke ring 12 is worn or broken, not only
the choke ring 12 and the choke member 14 will lose their air-tightness,
but also the choke ring 12 will be difficult to be replaced since
it is preset in the air passage 11 of the base body 10.
[0008] The present invention has arisen to mitigate and/or obviate
the afore-described disadvantages of the conventional switch of
a pneumatic tool.
SUMMARY OF THE INVENTION
[0009] The primary object of the present invention is to provide
a switch mechanism for a pneumatic tool which is capable of preventing
abrasion and broken of the inner wall of the air passage of the
base body and the choke ring.
[0010] The secondary object of the present invention is to provide
a switch mechanism for a pneumatic tool that can enable the user
to replace the worn or broke component of the switch mechanism with
ease.
[0011] A switch mechanism for a pneumatic tool in accordance with
the present invention comprises:
[0012] A choke ring is disposed in an air passage of the pneumatic
took and at a center of the choke ring is formed an air hole;
[0013] A control rod is swayably inserted through the air hole
of the choke ring in a manner that a first end of the control rod
corresponds to a trigger of the pneumatic tool;
[0014] A choke member is provided for insertion of a second end
of the control rod and pushed by a spring to seal the choke ring
with an end surface.
[0015] The characteristic of the present invention is that in the
air passage of the base body is disposed a bushing which is located
in between the choke member and the inner wall of the air passage
of the base body and between the choke member and the choke ring.
By such arrangement, the inner wall of the air passage of the base
body and the choke ring can be avoided from being abraded by the
choke member.
[0016] The present invention will become more obvious from the
following description when taken in connection with the accompanying
drawings, which show, for purpose of illustrations only, the preferred
embodiment in accordance with the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an assembly cross sectional view of a conventional
switch mechanism for a pneumatic tool;
[0018] FIG. 2 is a partial amplified view of FIG. 1;
[0019] FIG. 3 is an operational view of the conventional switch
mechanism for a pneumatic tool of FIG. 1;
[0020] FIG. 4 is an exploded view of a switch mechanism for a pneumatic
tool in accordance with the present invention;
[0021] FIG. 5 is an assembly cross sectional view of the switch
mechanism for a pneumatic tool in accordance with the present invention;
[0022] FIG. 6 is a partial amplified view of FIG. 5;
[0023] FIG. 7 is an operational view of the switch mechanism for
a pneumatic tool in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] Referring to FIGS. 4-6, a switch mechanism in accordance
with one aspect of the present invention is shown and generally
comprises: a choke ring 30, a control rod 40, a choke member 50
and a bushing 60. The switch mechanism is disposed in a base body
20 of a pneumatic tool.
[0025] The choke ring 30 is formed with a central air hole 31 and
disposed inside an air passage 21 of the base body 20. It is to
be noted that an annular protrusion 32 is formed downward about
the periphery of the air hole 31.
[0026] The control rod 40 is swayably inserted through the air
hole 31 of the choke ring 30 in a manner that a first end of the
control rod 40 corresponds to a trigger 22 of the base body 20.
[0027] The choke member 50 is provided for insertion of a second
end of the control rod 40, and about the periphery of the choke
member 50 is formed with a choke portion 51. A spring 52 is used
to push against a lower end surface 511 of the choke portion 51,
so that an upper end surface 511 of the choke 51 is pushed to seal
the air hole 31 of the choke ring 30.
[0028] The specialty of the present invention is that in the air
passage 21 of the base body 20 is installed with a metal-made bushing
60 whose hardness is greater than the hardness of the choke member
50. The bushing 60 has an annular abutting portion 61 and an annular
shoulder portion 62 located at an end of the annular abutting portion
61. The annular abutting portion 61 is used to abut against the
inner wall of the air passage 21 of the base body 20 and located
between the inner wall of the air passage 21 and annular periphery
513 of the choke portion 51 of the choke member 50. The annular
shoulder portion 62 is located between the upper end surface 511
of the choke portion 51 of the choke member 50 and a lower end surface
33 of the choke ring 30. The inner periphery of the annular shoulder
portion 62 is abutted by the annular protrusion 32 of the choke
ring 30, so that the lower end 321 of the annular shoulder 32 of
the choke ring 30 is able to closely abut against the upper end
surface 511 of the choke member 51 of the choke member 50.
[0029] Referring to FIG. 7, when the switch mechanism is in use,
the user can press the trigger 22 on the base body 20, such that
the control rod 40 is moved to swing an angle by the trigger 22
and synchronously enables the choke portion 51 of the choke member
50 to disengage from the annular protrusion 32 and the air hole
31 of the choke ring 30. At this moment, air is allowed to enter
the base body 20 for pneumatic operation via the air hole 31 of
the choke member 30. In addition, the control rod 40 also enables
the choke member 50 to swing an angle when being pushed by the trigger
22. Since the bushing 60 is disposed between the choke member 50
and the base body 20, and between the choke member 50 and the choke
ring 30. After the choke member 50 swings an angle, the choke portion
51 of which will press against the annular abutting portion 61 and
the annular shoulder portion 62 of the bushing 60 instead of pressing
directly against the inner wall of the air passage 21 of the base
body 20 and the choke ring 30. Thereby, the inner wall of the air
passage 21 of the base body 20 and the choke ring 30 can be avoided
from abrasion or broken.
[0030] Furthermore, the hardness of the bushing 60 is greater than
that of the choke member 50, the choke portion 51 of the choke member
50 will be worn after long time of abutting against the bushing
60. However, the choke member 50 is positioned inside the air passage
21 of the base body 20 by the spring 52, and the spring 52 is detachably
disposed in the air passage 21 of the base body 20. In this case,
it is easy for user to replace the choke member 50 after it is worn
or broken.
[0031] While we have shown and described various embodiments in
accordance with the present invention, it should be clear to those
skilled in the art that further embodiments may be made without
departing from the scope of the present invention. |