Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1999-08-30
2001-12-25
Larkin, Daniel S. (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S049800, C073S040700
Reexamination Certificate
active
06332350
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to leak testers used for defect tests of iron wheels and aluminum wheels of automobiles, for example. Particularly, this invention relates to leak testers which are capable of performing leak tests on multiple kinds of works, having different diameters, with a long life.
This application is based on Patent Application No. Hei 10-248760 filed in Japan, the content of which is incorporated herein by reference.
2. Description of the Related Art
Conventionally, engineers use leak testers for inspecting casting defects of iron wheels and aluminum wheels (hereinafter, simply referred to as “wheels”) of automobiles, for example.
FIG. 4
is a schematic illustration showing an example of a leak tester conventionally known. The leak tester of
FIG. 4
is basically constructed by a base
24
, a bell jar
25
, and a chamber
21
. Herein, the bell jar
25
is capable of moving up and down on the base
24
by way of chamber seals
32
, such as O-rings. A pipe
31
a
is arranged beneath the base
24
to introduce trace gas into the chamber
21
. Herein, the pipe
31
a
penetrates through an introduction opening
22
of the base
24
to communicate with the chamber
21
. A pipe
31
b
is arranged on an upper surface of the bell jar
25
to lead “leaked” trace gas, leaked in an inside of the chamber
21
, to a detector. The pipe
31
b
penetrates through a detection opening
23
of the bell jar
25
to communicate with the chamber
21
. A support rod
26
is inserted into a center hole of an upper portion of the bell jar
25
by way of a seal
33
, such as an O-ring. An end portion of the support rod
26
is interconnected to a work press plate
27
in the chamber
21
. Upper seals
28
having ring-like shapes are fixed to a lower surface of the work press plate
27
. In addition, lower seals
29
having ring-like shapes are fixed to an upper surface of the base
24
. As the seals
28
and
29
, it is possible to use plate rubber materials, which are cut in ring-like shapes.
A work (
30
) is supplied to the aforementioned leak tester, as follows:
First, a human operator (or worker) inserts a plug into a valve hole of a wheel, which serves as a work, by fingers. Then, the human operator moves the bell jar
25
upward to open the chamber
21
and pull up the work press plate
27
. The work
30
is arranged between the upper seals
28
and the lower seals
29
. Such arrangement of the work
30
is performed manually or automatically by using a robot, for example. Thereafter, the work press plate
27
is forced to descend down, so that rims
34
of the work
30
are tightly sandwiched between the upper seals
28
and the lower seals
29
. At the same time, the bell jar
25
is forced to descend down, so that the chamber
21
is closed.
FIG. 5
is a schematic illustration showing a contact state established between the lower seal
29
and the rim
34
of the work
30
. Due to compressive force being supplied from the work press plate
27
, the rim
34
is pressed against the lower seal
29
. Thus, the lower seal
29
partially becomes depressed at a contact area, surrounding areas of which are forced to rise.
After completion in arrangement of the work
30
in the leak tester, the leak tester evacuates air, which exists inside of the work
30
, from the introduction opening
22
by way of the pipe
31
a
. Then, the leak tester introduces trace gas such as helium gas into the work
30
from the introduction opening
22
by way of the pipe
31
a
. At the same time, the detector detects gas, which exists inside of the chamber
21
and which is lead thereto from the detection opening
23
by way of the pipe
31
b
. If the work
30
has a defect, the trace gas leaks from the inside of the work
30
, so that the chamber
21
will be filled with the trace gas. The detector detects the leaked trace gas. Thus, it is possible to detect existence of the defect and a size of the defect.
After completion of the test, the leak tester evacuates the trace gas from the work
30
, while air is flown into to chamber
21
. Then, the human operator takes the inserted plug by fingers and pulls it out from the valve hole. Thereafter, the human operator installs the next work having a valve hole into which a plug is inserted in the chamber
21
. Thus, it is possible to proceed to testing of the next work.
In the conventional leak tester described above, the work
30
is sealed while being sandwiched between the upper seals
28
and the lower seals
29
. So, compressive force is locally imparted to the upper seals
28
and the lower seals
29
. However, the conventional leak tester does not provide a support which supports the upper seals
28
and the lower seals
29
from their peripherals. For this reason, the upper seals
28
and the lower seals
29
must be noticeably deformed. That is, as shown in
FIG. 5
, the upper seal
29
(and the lower seal
28
) becomes partially depressed at the contact area, surrounding areas of which swell up. When the work is changed with another work having a different diameter, a position that compressive force affects changes as well, so an area of the seal being deformed is correspondingly changed. If such deformation repeatedly occurs, surfaces of the seals
28
and
29
must be abraded so as to cause formation of cracks. In that case, there is a problem that the leak test cannot be performed.
In addition, the surfaces of the lower seals
29
are formed like flat planes. So, when the work
30
is installed into the leak tester or when the work
30
is sandwiched between the seals, the work
30
is easily changed in location. That is, it is difficult to automatize supply process or removal process of the work
30
.
Further, when the plug is inserted into the valve hole of the wheel, the human operator uses his or her fingers to insert or extract it. Such manual operations for insertion and extraction are not good in work efficiency. Once the air is evacuated from the work so that the inside of the work is placed in a decompressed state, the plug must be tightly attached to the work. In that case, a large force is required to extract the plug from the work. However, it is difficult to apply sufficient extraction force to the plug by fingers. In addition, reliability of the leak test is reduced due to abrasion of the plug.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a leak tester which is capable of improving a reliability of a leak test by reducing abrasion of sealing members.
It is another object of the invention to provide a leak tester which is capable of easily installing a work therein.
A leak tester of this invention is basically designed to perform a leak test on a work such as a wheel by detecting trace gas being leaked from the work. Herein, the work is installed in a chamber and is tightly held between seals.
This invention employs a leak tester seal constructed using a work seal base, on which a number of channels are formed like circular rings, which are sequentially arranged with equal intervals. In addition, a number of sealing members are formed like circular rings, which are fitted into the channels, respectively. Herein, the sealing members are made of elastic material providing desired elasticity, while the work seal base is made of material whose hardness is higher than the sealing members. For this reason, even if the sealing member is depressed by the work, the work seal base is hard to deform, so that it is possible to reduce deformation of the leak tester seal as a whole. In addition, the sealing members are fitted into the channels of the work seal base, so each sealing member is not deformed greatly in response to a compressive force applied thereto from the work. Thus, it is possible to reduce friction between the sealing member and the work. As a result, it is possible to improve reliability in leak testing.
It is preferable that the upper surfaces of the channels differ from each other in heights like steps. In that case, it is possible to use an interior w
Inoue Akifumi
Katoh Takeshi
Kubota Kazushige
Takahashi Hidemi
Larkin Daniel S.
Ostrolenk Faber Gerb & Soffen, LLP
Yamaha Corporation
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