Apparatus and method for cleaning condenser tubes of a refrigerator

In a refrigerator of a compression type or an absorption type, including a condenser and an evaporator, an apparatus for cleaning condenser tubes in which a cleaning brush movably mounted in each tube is moved through the tube by reversing a flow of cooling fluid therethrough so that the inner wall of the tube can be cleaned by the moving cleaning brush. Switching means switches from a temperature control means which controls refrigeration capacity depending upon temperature of a cooling and heating medium within the evaporator during the refrigeration operation, to control by pressure restriction means which restricts the pressure within the condenser to not exceed a predetermined value, before the flow of the cooling fluid in the tube is changed for cleaning the tube. When the inner pressure of the condenser is lowered at least by a fixed value from the predetermined value, the flow of cooling fluid may be changed within the condenser without changing from the temperature control to the pressure restriction control. Method for cleaning the condenser tubes of a refrigerator in this fashion is also provided.

BACKGROUND OF THE INVENTION 
The present invention relates to an apparatus and method for cleaning 
condenser tubes as well as absorber tubes, within a refrigerator of the 
absorption type or in a compression type refrigerator having a centrifugal 
or a screw compressor. 
In conventional apparatus and methods for cleaning condenser tubes of a 
refrigerator having a condenser and an evaporator, a cleaning brush is 
movably mounted within each respective tube that has chambers for 
capturing the cleaning brush at the opposite ends thereof. Thus the 
cleaning brush resides in one or the other of these oppositely-disposed 
chambers during normal operation of the refrigerator. When the tubes are 
to be cleaned, the cleaning brush is moved through the tube by reversing 
the flow of fluid such as cooling water therethrough. This is carried out 
by altering the flow path of the fluid such as cooling water by means of a 
flow path change valve, so that the inner wall of the tube can be cleaned 
by the moving cleaning brush. 
However, in these conventional cleaning apparatus and methods, a period of 
time arises in which the amount or the rate of the cooling water flow is 
slight or non-existent, when the flow of the same is reversed during the 
cleaning operation. In this period, the pressure within the condenser 
rises, resulting in a high pressure trip or an overload of a motor 
depending upon the loading condition, or a surging phenomenon within the 
centrifugal compressor, together with the occurrence of noises and 
vibrations, all being disadvantageous effects. 
FIG. 1, illustrates conditions during 100% operation of a conventional 
turbo refrigerator utilizing Freon 11 (trade name) as the refrigerant, 
when the flow path of the cooling water is changed. 
In a conventional refrigerator, a temperature controller for controlling a 
cooling and heating medium such as a cooling water and a brine within the 
evaporator is provided, which controls refrigeration capacity depending 
upon a temperature signal representing a temperature detected within the 
cooling and heating medium during the refrigeration operation. 
In order to eliminate such defects within conventional cleaning apparatus 
and processes, the timing for changing the flow path of the cooling water 
is advanced, or actuated when the load is low or the refrigerator is 
stopped. However, even when the timing for changing the flow path is 
advanced, the period inevitably arises where the flow amount or rate of 
the cooling water is slight or non-existent. Therefore, it is extremely 
difficult, if not impossible, to eliminate the aforementioned 
disadvantages. 
Furthermore, while changing the cooling water flow direction through the 
condenser tubes during the period of low loading or stands still of the 
refrigerator might help to alleviate the above-noted problems, the 
cleaning operation naturally can not then be conducted at fixed intervals 
or at desired times. Thus, this just results in an undesirably smaller 
cleaning effect. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an 
apparatus and method for cleaning condenser tubes within a refrigerator, 
eliminating the above-noted disadvantages. 
It is also an object of the present invention to provide for feasible 
cleaning of condenser tubes within a refrigerator at any fixed or 
conveniently desired time. 
It is another object of the present invention to provide for feasible, 
effective cleaning of condenser tubes within a refrigerator without 
unwanted pressure build-up occurring within the condenser. 
It is also another object of the present invention to minimize or totally 
eliminate noise and vibrations and unwanted surging that occur during the 
cleaning of condenser tubes within a refrigerator. 
It is a further object of the present invention to provide for effective 
control of pressure within the condenser of a refrigerator, so that such 
pressure will not exceed a predetermined, fixed value. 
It is even a further object of the present invention to provide for smooth, 
steady refrigeration, with minimal interruption thereof during a cleaning 
operation of tubes within the refrigerator. 
These and other objects are attained by the present invention which in one 
aspect is directed to an apparatus for cleaning condenser tubes of a 
refrigerator including a condenser and an evaporator, wherein a cleaning 
brush is movably mounted within each respective tube and is moved 
therethrough by reversing flow of fluid such as cooling water through the 
tube so that an inner wall of each tube will be cleaned by the respective 
moving cleaning brush. Means for controlling the temperature of a cooling 
and heating medium in the evaporator is also provided, to control the 
refrigeration capacity depending upon a temperature of the cooling and 
heating medium within the evaporator, during the refrigeration operation. 
The improvement of the present invention in this aspect comprises pressure 
restriction means for restricting an internal pressure of the condenser so 
as not to exceed a predetermined value, and also switching means which 
selectively actuates control by either the temperature control means or by 
the pressure restricting means, wherein the control by the temperature 
control means is switched over to the control by the pressure restricting 
means before the flow of the cooling water through the condenser tubes is 
changed for cleaning the same. Thus the internal pressure of the condenser 
is controlled to not exceed the predetermined value, during the cleaning 
of the tubes therein. 
In another aspect, the present invention is directed to a method of 
cleaning tubes within a refrigerator, such as condenser tubes mounted 
within a condenser therein, in which a cleaning brush is movably mounted 
within each respective condenser tube. This is accomplished by controlling 
the internal pressure within the condenser, and then reversing the flow of 
fluid through the condenser tubes after the internal pressure of the 
condenser has been so controlled.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, where similar or corresponding components are 
designated by like reference numerals throughout the different figures, 
one embodiment of an apparatus and method for cleaning condenser tubes of 
a refrigerator is illustrated in FIG. 2. 
As illustrated in FIG. 2, a motor 1 drives a compressor 2 of a centrifugal 
type, with a suction vane 3 being provided for controlling an 
inspirational amount of fluid at an inlet of the compressor 2. The suction 
vane 3 is controlled by a vane motor 4. A condenser 5 and an evaporator 6 
are cooperatively coupled to one another, i.e. the condenser 5 is coupled 
onto the evaporator 6. Fluid such as cooling water is supplied to a tube 9 
or 10 within the condenser 5, via a four-way valve 8 by a pump 7. The 
cooling water is then passed out of the tube 9 or 10 to a cooling tower 11 
via the four-way valve 8, while the cooling water condenses a refrigerant 
vapor to liquify the same within the condenser 5. The cooling water cooled 
within the cooling tower 11 is then fed to the pump 7. 
A fluid to be cooled such as water or brine, is supplied to the tubes 12 
within the evaporator 6 and serves as a cooling and heating medium. This 
water or brine evaporates the refrigerant liquid within the evaporator 6 
as the water or brine flows through the tubes 12 therein, with the water 
or brine thereby being cooled at the same time by the latent heat of 
vaporization of the refrigerant liquid. In the illustrated embodiment, the 
evaporator 6 operates as a cooler. 
The compressor 2 inspires the refrigerant vapor from the evaporator 6 
through the suction vane 3, and discharges compressed refrigerant vapor 
into the condenser 5. The condensed refrigerant within the condenser 5 is 
then passed to the evaporator 6 via a float chamber and a float valve. A 
portion of the condensed refrigerant is circulated from the evaporator 6 
to the motor 1 for cooling, through a conduit which is splayed into the 
motor 1 as illustrated, and then is passed back to the evaporator 6 via 
another conduit after having cooled the motor 1. 
The temperature of the thus-cooled water or brine discharged from the tube 
12 of the evaporator 6 is detected by a temperature detector 13. The 
temperature detector 13 is connected to a controller 14 which controls the 
temperature of the cooling and heating medium such as the water or brine, 
and which controls refrigeration capacity by using a temperature signal 
sent from the temperature detector 13. The controller 14 sends a control 
signal the vane motor 4 in order to control the vane 3, thereby 
controlling the refrigeration capacity. The vane motor 4 controls the 
suction vane 3 as a capacity valve, depending upon the control signal 
received, so that the temperature of the cool water or brine at the outlet 
of the tube 12 from the evaporator 6, may attain a predetermined value. 
Switching means 23 is coupled with the controller 14. This switching means 
23 changes the functions of the controller 14, i.e. the function as the 
temperature control device for the cooling and heating medium such as the 
cool water and brine within the evaporator tubes 12 as described above, 
and the function as a pressure restriction device for controlling the 
internal pressure of the condenser 5, to not exceed a predetermined value, 
as described below. 
The cleaning operation will no be described with reference to FIG. 3, which 
illustrates one individual condenser tube 9. This condenser tube 9 is 
mounted to tube plates 15 at opposite ends thereof, and a cleaning brush 
16 is movably inserted into the tube 9. The opposite ends of the tube 9 
open into liquid chambers 17 and 18 respectively, as illustrated in FIG. 
2. A pair of chambers 19 and 20 for capturing the cleaning brush 16 are 
mounted at the opposite ends of the tube 9, to project into the liquid 
chambers 17 and 18 respectively, as illustrated. The chambers 19 and 20 
are provided with openings 21 and 22 respectively, through which the 
cooling water can flow to and from the respective liquid chambers 17 and 
18. 
During the refrigeration operation, the four-way valve 8 is positioned in 
one position as illustrated by the solid lines in FIG. 2, and the cooling 
water flows in the leftward direction through the tube 9, as illustrated 
by the arrows in FIG. 3. Therefore, the cooling water flowing through the 
tube 9 pushes the cleaning brush 16 to the left, so that the brush 16 is 
captured within the left-hand side chamber 20. 
When the tube 9 is to be cleaned, the four-way valve 8 is turned to another 
position as illustrated by the broken lines in FIG. 2, so that the flow of 
the cooling water within the tube 9 is reversed towards the right side 
thereof. Then, the cleaning brush 16 is pushed by the water flowing in the 
opposite direction to move in the rightward direction through the tube 9, 
resulting in the cleaning brush being captured in the right-hand side 
chamber 19. While the cleaning brush 16 is moving through the tube 9, the 
inner wall of the tube 9 is cleaned by the moving cleaning brush. Such a 
flow path change or alteration is conducted at proper intervals by turning 
the four-way valve 8, to thereby clean the condenser tubes 9 and 10. 
On beginning the cleaning of the tubes, in order to prevent an 
extraordinary rise in the pressure in the condenser 5 beyond the 
predetermined value, which is caused by changing the flow path of the 
cooling water as noted, the cleaning operation is carried out by an order 
illustrated in the accompanying flow diagram of FIG. 4. 
Referring to FIG. 4, a twenty-four hour timer or the like is used as the 
switching means 23, with the time for changing the flow path being 
predetermined by this timer, e.g. every eight hours or three times a day. 
Therefore, the cleaning operation will be automatically performed at 
regular intervals. 
The controller 14 which normally functions as the temperature control 
device for the cooling and heating medium such as the water and the brine 
within the evaporator tubes 12, thus controlling the refrigeration 
capacity by detecting the temperature of the water or brine, is switched 
to operate as the pressure restriction device, in preference to the 
temperature control device, by the switching means 23 when cleaning the 
tubes 9 and 10. 
Then, the controller 14 sends a control signal to the vane motor 4 for 
reducing refrigeration capacity by reducing the inspirational amount of 
refrigerant supplied to the compressor 2. Then, the vane motor 4 controls 
the suction vane 3 as a capacity valve to close the same either completely 
or to a predetermined minimum open amount. In other words, refrigeration 
capacity is controlled by the controller 14 as the pressure restriction 
device, in proportion to the amount of refrigerant inspired by the 
compressor 2. In this situation, the controller 14 functioning as the 
pressure restriction device results in lower refrigeration capacity as 
compared to the functioning as the temperature control device during the 
overall refrigeration operation, as described above. Thus it is quite 
clear that alteration in the direction of the cooling water through the 
condenser tubes 9 and 10 may be then conducted, after it has been 
determined that the refrigeration capacity is nonexistent or has reached 
the predetermined minimum level. 
When a screw-type compressor is used, a slide vane is opened completely or 
to a predetermined maximum level, in order to determine that the 
refrigeration capacity is nonexistent or has reached the predetermined 
minimum amount. 
The operation for changing the flow path of the cooling water through the 
condenser tubes 9 and 10 is completed in little time, in order to minimize 
influence on the burden or loads. Thus, this alteration in the flow path 
is completed within ten seconds, in the particular embodiment. 
The refrigerator illustrated in FIG. 2 is provided with a water shut-off 
detectional relay (not illustrated) which is a type of safety device for 
stopping operation of the refrigerator of FIG. 2 when the flow of the 
cooling water through the tubes 9 and 10 is shut-off or stops completely, 
or becomes nonexistent, in order to prevent breaking down of the 
refrigerator. 
Therefore, in general, when the flow path of the cooling water is altered, 
the flow of the cooling water inevitably stops or becomes nonexistent, and 
thus the water shut-off detection relay is actuated, which results in 
stopping the operation of the refrigerator itself. Therefore, according to 
the present invention, during the operation of altering the flow path of 
the cooling water through the condenser tubes 9 and 10, it is necessary to 
disable the water shut-off detection relay. This disabling is performed by 
short-circuiting the water shut-off detection relay before the flow path 
is changed, as illustrated in the schematic diagram of FIG. 4. 
A short interval timer T is used for stabilizing the flow system of the 
fluid before changing the flow thereof to the return direction, as 
illustrated in FIG. 4. A red colored lamp RL is switched on when the 
refrigerator is operated, while an orange colored lamp OL is switched on 
when the time of the twenty-four hour timer is up for conducting the tube 
cleaning, i.e. when the order for changing the flow path is performed. The 
orange colored lamp is switched off when the flow path is returned to the 
original direction, i.e. when the cleaning of the tubes is completed. 
As described above, the controller 14 is switched from the temperature 
control device to the pressure restriction device by the switching means 
23, when cleaning the tubes. This results in a lower refrigeration 
capacity as compared with the refrigeration capacity resulted by the 
temperature control device during the normal operation. However, such a 
lower refrigeration capacity can be obtained by controlling the compressor 
to reduce its rotational speed. In other words, the refrigeration capacity 
may be controlled in proportion to the rotational speed of the compressor 
in a rotation-type of refrigerator. 
Another embodiment of the apparatus and method of the present invention for 
cleaning condenser tubes of a refrigerator is illustrated in FIG. 5. This 
illustrated embodiment has a similar structure to the first embodiment 
illustrated in FIG. 2, and thus description of the same or similar parts 
having the same reference numerals have been omitted for the sake of 
brevity. 
In the embodiment illustrated in FIG. 5, a compressor 2 inspires a 
refrigerant vapor from an evaporator 6 through a capacity valve 33, and 
discharges a thus-compressed refrigerant vapor to a condenser 5. A 
temperature detector 13 detects the temperature of the water or brine at 
the outlet of the evaporator tubes 12 within the evaporator 6, and then 
transmits a temperature signal to a temperature control means 34, for 
controlling a cooling and heating medium such as water or brine, to a 
predetermined temperature value. 
The temperature control means 34 receives the temperature signal from the 
temperature detector 13 and transmits a control signal for controlling the 
capacity valve 33, to switching means 35. A common contact point 35a of 
the switching means 35 is connected to the capacity valve 33. 
Pressure restriction means 36 for restricting the internal pressure within 
the condenser 5 in order not to exceed a predetermined value, detects the 
internal pressure within the condenser 5 and outputs a control signal for 
controlling the capacity valve 33, to the switching means 35. 
When the internal pressure within the condenser 5 is below the 
predetermined value, the common contact point 35a of the switching means 
35 leads to a contact point T which is in turn connected to the 
temperature control means 34, thereby conducting the temperature control 
of the cool water or brine within the evaporator tubes 12, by the 
temperature control means 34. When the internal pressure within the 
condenser 5 is above the predetermined value, then the common contact 
point 35a of the switching means 35 leads to a contact point P which is 
connected to the pressure restriction means 36, thereby conducting the 
pressure restriction control of the condenser 5 by the pressure 
restriction means 36, to prevent any extraordinary rise of the internal 
pressure within the condenser 5. 
According to the present invention, it is possible for the pressure 
restriction means 36 to detect the temperature within the condenser 5 and 
then control the capacity valve 33 depending upon the detected temperature 
therein in order not to exceed a predetermined temperature level, thereby 
controlling internal pressure within the condenser 5 to remain below the 
predetermined value. 
When a pressure or temperature which is obtained by detection within the 
condenser 5 preceding the cleaning of the tubes is then lowered by at 
least a fixed amount from the predetermined value, it may become 
unnecessary to switch over from the temperature control to the pressure 
restriction control. In other words, it may be possible to change the flow 
path of the cooling water through the condenser tubes 9 and 10 without 
switching over from the temperature control to the pressure restriction 
control, because, even when a high pressure trip occurs in the condenser 
5, the inner pressure within the condenser 5 cannot exceed the 
predetermined value. 
Although the invention has been explained with reference to preferred 
embodiments of a compression-type refrigerator, the present invention may 
be also applied to an absorption-type refrigerator. In this instance, 
components such as an absorber (means for absorbing a refrigerant gas), a 
solution pump (means for transferring to a high pressure portion), and a 
generator (means for generation of a refrigerant gas) correspond to the 
compressor on the refrigeration cycle in the absorption-type refrigerator. 
The present invention can be applied to the absorber and to the condenser 
having the tubes for the cooling liquid such as water within the 
absorption-type refrigerator, with the same results as those attained with 
compression-type refrigerators according to the present invention. 
In the above description of the preferred embodiments, the term "condenser" 
also includes an absorber of an absorption-type refrigerator. 
Although the present invention has been described with reference to 
preferred embodiments thereof illustrated in the accompanying drawings, it 
is quite clear to one of skill in the art that various changes and 
modifications can be made without departing from the scope of the present 
invention.