[0001] The invention relates to cleaning apparatus and methods.
[0002] Where objects are to be cleaned, various types of cleaning apparatus have been used
depending upon the type of object that is to be cleaned and the degree of cleaning
that is desired. For example, ultrasonic cleaning apparatus has conventionally been
used in cases where a fluid detecting element of the type disclosed in Japanese Patent
Publication (Kokoku) No. 59-47256 is to be cleaned. In that publication, the fluid
detecting element comprises a pair of conductors which are separated by continuously
porous, expanded polytetrafluoroethylene (EPTFE) containing a conducting substance
which is sandwiched between the conductors. This fluid detecting element is utilized,
for example, as an oil leakage sensor. Specifically, the abovementioned substance
exhibits an increase in insulation resistance when it is permeated by an oil, such
as heavy oil or gasoline. This electrical change is detected by a detector which is
connected to the abovementioned conductors, so that the presence or absence of oil
leakage is determined electronically. Such an oil leakage sensor must be regenerated
by cleaning after it has detected oil leakage, or periodically when the sensor has
been used over a long period of time even if no oil leakage is detected. In the past,
an ultrasonic cleaning apparatus of the type mentioned above has been used for such
cleaning.
[0003] However, oil leakage sensors of the type mentioned are of various shapes and sizes.
Accordingly, in cases where, for example, a long oil leakage sensor is to be ultrasonically
cleaned, a large ultrasonic cleaning apparatus capable of accommodating this sensor
is required. However, a conventional large ultrasonic cleaning apparatus is extremely
expensive.
[0004] Accordingly, there exists a demand for inexpensive cleaning apparatus which has cleaning
thoroughness comparable to that of ultrasonic cleaning apparatus.
[0005] According to the invention, there is provided cleaning apparatus, comprising a cleaning
tank for receiving a cleaning solution and an object to be cleaned, and fluid supply
means for supplying a fluid comprising air which is injected as bubbles into said
cleaning solution, said fluid striking the object to be cleaned, said fluid supply
means supplying said fluid at a high velocity and with such force that said air bubbles
burst upon striking said object, thereby producing shock waves, including ultrasonic
waves, which provides thorough cleaning of said object.
[0006] According to the invention, there is also provided a method of cleaning an object
comprising the steps of placing the object in a cleaning solution, and injecting air
as bubbles into the cleaning solution such that the velocity at which the bubbles
strike the object causes them to burst thereby producing shock waves including ultrasonic
waves which provide thorough cleaning of the object.
[0007] Cleaning apparatus embodying the invention, and cleaning methods according to the
invention, will now be described, by way of example only, with reference to the accompanying
drawing which is an exploded perspective view, partly broken away, of the apparatus.
[0008] The cleaning apparatus to be described comprises a cleaning tank which accomodates
a cleaning solution and an object to be cleaned, and fluid supply means for supplying
a fluid containing air which is injected as bubbles into the cleaning solution, the
fluid striking the object to be cleaned. The fluid supply means supplies the fluid
at a high velocity and with sufficient force that the air bubbles burst upon striking
the object, thereby producing shock waves, including ultrasonic waves, which provides
thorough cleaning of the object. The fluid may be air or a cleaning solution. The
cleaning solution preferably is xylene or methyl ethyl ketone.
[0009] More specifically, the cleaning apparatus to be described is characterized by the
fact that it is equipped with (a) a cleaning tank which accomodates a cleaning solution
and the object to be cleaned, and (b) a fluid supply means which supplies a fluid
containing air that is released into the cleaning solution so that it strikes the
object that is to be cleaned in the cleaning tank.
[0010] The air that is released into the cleaning solution forms air bubbles, which strike
the object that is to be cleaned in the cleaning solution with sufficient force that
they burst. When these air bubbles burst, shock waves, including ultrasonic waves,
are generated, and these waves excite a vibration in the object that is to be cleaned.
The cleaning solution is thus agitated by the fluid containing air that is released
into the cleaning solution, so that the cleaning solution is constantly in fluid motion.
As a result, these two effects act in combination so that the object that is to be
cleaned can be cleaned with extreme thoroughness.
[0011] The principal constituent elements of the cleaning apparatus 1 are a supporting cart
2, a cleaning tank 3 and a compressor including fluid supply means 4.
[0012] The supporting cart 2 consists of a base 2b which is equipped with wheels 2a so that
it is free to move. A pair of supports 2c are installed upright facing each other
on the top surface of the base 2b in order to support the cleaning tank 3.
[0013] The cylindrical cleaning tank 3 is preferably made of stainless steel, is open at
the top and is supported by the supports 2c so that the tank 3 is free to rotate about
a diameter of the tank as the axis of rotation. The axis of rotation is positioned
at a point above the midpoint on the axial line of the cleaning tank 3, so that when
the cleaning tank 3 is in a state of natural rest, the open end of the tank is positioned
at the top as shown in the figure. Xylene is a preferred cleaning solution 5 and is
accomodated in the cleaning tank 3 as an oil solvent.
[0014] The compressor 4 is installed on the base 2b of the supporting cart 2. Tube 4a, which
preferably is made of Teflon (trade mark) fluorocarbon resin and which is connected
to the compressor 4, is inserted into the cleaning tank 3, and the tip of this tube
4a is fastened to the bottom of the interior of the cleaning tank 3 so that the tip
points upwardly.
[0015] In the Figure, basket 6, preferably a mesh made of stainless steel, is used when
an oil leakage sensor or other object 7 to be cleaned is inserted into the cleaning
tank 3. Specifically, the oil leakage sensor 7 is accomodated inside the mesh basket
6, and is inserted into the cleaning tank 3 along with the mesh basket 6. A flange
6a at the upper end of the mesh basket 6 catches on the upper edge of the cleaning
tank 3, so that the oil leakage sensor 7 is suspended inside the cleaning tank 3,
and so that the sensor 7 is submerged in the xylene cleaning solution 5.
[0016] As described above, the oil leakage sensor 7 may comprise a pair of conductors 7a,7b
and a continuously porous EPTFE separator 7c containing a conductive substance interposed
between the conductors.
[0017] In operation of the cleaning apparatus 1, the oil leakage sensor 7 is accomodated
inside the cleaning tank 3 and submerged in xylene cleaning solution 5 as described
above, and the compressor 4 is started. Compressed air or other fluid containing air
fed from the compressor 4 passes through the tube 4a and is continuously released
into the xylene cleaning solution 5 as air bubbles from the tip of the tube inside
the cleaning tank 3. Because compressed air is thus continuously released into the
xylene cleaning solution 5, the xylene cleaning solution 5 inside the cleaning tank
3 is constantly in a state of highly agitated fluid motion. The air bubbles released
into the xylene cleaning solution 5 rise and strike the oil leakage sensor 7 with
sufficient force that they burst. Shock waves, including ultrasonic waves, are generated
at this point, and these waves excite a vibration in the oil leakage sensor 7.
[0018] As a result of a synergistic effect of the fluid motion of the xylene cleaning solution
5 and the excitation of vibration in the oil leakage sensor 7, the oil permeating
the oil leakage sensor 7 is dissolved in the xylene cleaning solution 5, so that the
oil leakage sensor 7 is cleaned and regenerated to approximately the same degree as
when a similar cleaning is performed using a conventional ultrasonic cleaning apparatus.
[0019] Thus, although the cleaning apparatus 1 described has an extremely simple structure,
it has a cleaning efficiency and thoroughness which is appoximately the same as that
of an ultrasonic cleaning apparatus. Compared to an ultrasonic cleaning apparatus,
the cleaning apparatus 1 is extremely inexpensive, and this reduced expense becomes
more pronounced as the size of the apparatus required increases.
[0020] The invention is not limited to the above example. Various configurations may be
employed. For example, in the apparatus as described above, the fluid containing air
consisted only of air. However, this fluid could also be a cleaning solution containing
air bubbles. In such case, the fluid supply means used would be a pump. The cleaning
apparatus could also be applied to various other objects besides oil leakage sensors,
and the cleaning solution used could be a cleaning agent other than xylene, such as,
for example, methyl ehtyl ketone.
[0021] As described above, the apparatus makes it possible to obtain a very inexpensive
cleaning apparatus which has a simple structure, but which has a cleaning effect comparable
to that of conventional ultrasonic cleaning apparatus.
[0022] While the invention has been disclosed herein in connection with certain embodiments
and detailed descriptions, it will be clear to one skilled in the art that modifications
or variations of such details can be made without deviating from the gist of this
invention, and such modifications or variations are considered to be within the scope
of the claims hereinbelow.
1. Cleaning apparatus, comprising a cleaning tank (3) for receiving a cleaning solution
(5) and an object (7) to be cleaned, and characterised by fluid supply means (4,4a)
for supplying a fluid comprising air which is injected as bubbles into said cleaning
solution (5), said fluid striking the object (7) to be cleaned, said fluid supply
means (4,4a) supplying said fluid at a high velocity and with such force that said
air bubbles burst upon striking said object (7), thereby producing shock waves, including
ultrasonic waves, which provides thorough cleaning of said object.
2. Apparatus according to claim 1 characterised in that said fluid consists of air.
3. Apparatus according to claim 1, characterised in that said fluid is a cleaning
solution containing air.
4. Apparatus according to any preceding claim, in that the or each said cleaning solution
is xylene.
5. Apparatus according to any one of claims 1 to 3, characterised in that the or each
said cleaning solution is methyl ethyl ketone.
6. A method of cleaning an object, comprising the step of placing the object (7) in
a cleaning solution (5) and characterised by the step of injecting air as bubbles
into the cleaning solution (5) such that the velocity at which the bubbles strike
the object (7) causes them to burst thereby producing shock waves including ultrasonic
waves which provide thorough cleaning of the object (7).
7. A method according to claim 6, characterised in that the air is injected contained
in a fluid.
8. A method according to claim 7, characterised in that the fluid is a cleaning solution.