CN110595138A

CN110595138A - Air return device, refrigerator and refrigerator control method

Info

Publication number: CN110595138A
Application number: CN201910948121.1A
Authority: CN
Inventors: 韩鹏; 卢起彪; 邓涵; 郭瑞水; 刘畅; 王铭坤; 孙哲
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2019-10-08
Filing date: 2019-10-08
Publication date: 2019-12-20

Abstract

The invention relates to an air return device, a refrigerator and a refrigerator control method, wherein the air return device comprises an air return pipe, a cold air pipe and a bypass pipe, an air return inlet of the air return pipe can be communicated with a refrigerating chamber, an air return outlet of the air return pipe can be communicated with the refrigerating chamber, a cold air inlet of the cold air pipe can be communicated with the refrigerating chamber, a cold air outlet of the cold air pipe can be communicated with the refrigerating chamber, the bypass pipe is communicated between the air return pipe and the cold air pipe and used for guiding an air return part in the air return pipe into the cold air pipe, a position on the cold air pipe, which is communicated with the bypass pipe, is a bypass inlet, a part on the cold air pipe, which is positioned between the bypass inlet and the cold air outlet, is a mixed pipe section, and. When the temperature in the mixed pipe section is lower than a certain value, the heating element is opened, so that the effect of defrosting or avoiding frosting is achieved, and the reliable implementation of refrigeration and humidity control in the refrigerating chamber is effectively guaranteed.

Description

Air return device, refrigerator and refrigerator control method

Technical Field

The invention relates to the field of household appliances, in particular to an air return device, a refrigerator and a refrigerator control method.

Background

With the improvement of living standard of people, the requirements on preservation and energy conservation of the refrigerator are higher and higher. The air return device is arranged in the refrigerator, so that air in the refrigerating chamber and the freezing chamber can circulate, the humidity of the refrigerating chamber is reduced, and an energy-saving effect is achieved. However, after the refrigerator runs for a period of time, the refrigerator is prone to have the problems that the refrigerating effect is poor, and the humidity in the refrigerating chamber cannot be reliably controlled.

Disclosure of Invention

Based on this, it is necessary to provide an air return device, a refrigerator, and a refrigerator control method to secure the reliability of the cooling effect and the humidity control.

The utility model provides an air return device, includes return air pipe, cold wind pipe and bypass pipe, the return air entry of return air pipe can communicate with the walk-in, the return air export of return air pipe can communicate with the freezer, the cold wind entry of cold wind pipe can communicate with the freezer, the cold wind export of cold wind pipe can communicate with the walk-in, the bypass pipe intercommunication is in return air pipe with between the cold wind pipe, be used for with return air part among the return air pipe is leading-in the cold wind pipe, the cold wind pipe on with the position of bypass pipe intercommunication is the bypass entry, lie in on the cold wind pipe bypass entry with the part between the cold wind export is the mixing tube section, the mixing tube section is equipped with the heating member.

The above-mentioned scheme provides an air return device, the return air pipe can with the air in the freezer is leading-in the freezer, then the cold air in the freezer is followed again the cold-blast main flows in the freezer realizes the regulation to freezer humidity and temperature. By further arranging the bypass pipe, when the humidity in the refrigerating chamber is smaller than a humidity set value, the circulation of the bypass pipe is increased, and the proportion of return air in the mixed pipe section is increased. However, there is a risk of frost formation when the relatively humid return air is mixed with the relatively cold air flowing from the freezer compartment into the cold air duct at a relatively low temperature in the mixing duct section. And when the temperature in the mixing pipe section is lower than a certain value, the heating element is opened to achieve the effect of defrosting or avoiding frosting, so that the reliable operation of refrigeration and humidity control in the refrigerating chamber is effectively guaranteed.

In one embodiment, the heating element is arranged on the wall of the cold air pipe, or the heating element is arranged in the pipe cavity of the cold air pipe.

In one embodiment, the heating element is disposed at the bypass opening.

In one embodiment, the air return device further comprises a water drainage channel, and the water drainage channel penetrates through the side wall of the cold air pipe and is used for guiding out defrosting water in the cold air pipe.

In one embodiment, a defrosting water collecting tank is arranged on the inner wall of the cold air pipe, the defrosting water collecting tank is distributed along the circumferential direction of the inner wall of the cold air pipe, the defrosting water collecting tank is located below the heating element, and a water inlet formed on the inner wall after the water drainage channel penetrates through the side wall of the cold air pipe is communicated with the defrosting water collecting tank.

In one embodiment, the defrosting water collecting tank is communicated with the water inlet at a position lower than other parts of the defrosting water collecting tank.

In one embodiment, the air return device further comprises a water receiving tray, and a water outlet of the drainage channel corresponds to the water receiving tray and is used for guiding defrosting water into the water receiving tray.

In one embodiment, the number of the return air pipes and the number of the bypass pipes are two, the two return air pipes are respectively located at two sides of the cold air pipe, the bypass pipes correspond to the return air pipes one by one, the water receiving tray is located below the return air pipes and the cold air pipe, the middle of the water receiving tray corresponds to the cold air pipe, and the middle of the water receiving tray is recessed downwards to form a collecting area.

The utility model provides a refrigerator, includes walk-in, freezer and foretell return air device, the return air entry of return air pipe with the walk-in intercommunication, the return air export of return air pipe with the freezer intercommunication, the cold wind entry of cold blast pipe with the freezer intercommunication, the cold wind export of cold blast pipe with the walk-in intercommunication.

According to the scheme, the refrigerator is provided, by arranging the air return device in any one of the embodiments, when the air return pipe, the bypass pipe and the cold air pipe realize the control of the humidity and the temperature in the refrigerating chamber, the heating element further guarantees the reliable operation of the refrigerating process and the humidity control process in the refrigerating chamber.

In one embodiment, the refrigerating chamber is provided with a humidity detection part, the cold air pipe is internally provided with a temperature detection part, the return air pipe is provided with a return air door, the return air door is positioned at the lower part of the return air pipe communicated with the bypass pipe, a bypass air door is arranged at the inlet of the bypass pipe, a bypass air mixing door is arranged at the outlet of the bypass pipe, the cold air pipe is provided with a cold air mixing door, the cold air mixing door is positioned below the bypass inlet, the humidity detection part is electrically connected with the return air door, the bypass air mixing door and the cold air mixing door, and the temperature detection part is electrically connected with the heating part.

In one embodiment, the temperature sensing member is located in the mixing section.

In one embodiment, the refrigerator further comprises an evaporator located between the return air outlet and the cold air inlet.

A refrigerator control method is used for controlling the refrigerator and comprises the following steps:

acquiring a humidity value H in the refrigerating chamber, and comparing the size relation between the humidity value H and a humidity set value H1;

if H is less than H1, increasing the circulation of the bypass pipe and reducing the circulation of return air flowing into the freezing chamber from the return air pipe;

acquiring the temperature T of the pipe wall of the mixing pipe section, and comparing the size relation between the temperature T and a temperature set value T1;

if T is less than T1, the heating element is activated.

The above-mentioned scheme provides a refrigerator control method for controlling the refrigerator described in any of the above-mentioned embodiments, and when the humidity value H in the refrigerating chamber is smaller than the humidity set value H1, it proves necessary to increase the humidity in the refrigerating chamber. Thereby increasing the flow of the bypass line and decreasing the flow of return air from the return air duct into the freezer compartment. And detecting the temperature T of the pipe wall of the mixing pipe section, and if the temperature T is less than a set temperature value T1, proving that the temperature of mixed air mixed with return air and cold air in the mixing pipe section is low, and frosting and risks exist. Therefore, the heating element is started to heat the mixing pipe section, the effect of defrosting or avoiding frosting is achieved, and the reliable operation of the humidity adjustment and the refrigeration process in the refrigerating chamber is guaranteed.

In one embodiment, the refrigerator control method further includes the steps of:

after the heating element is activated for a time period of t1, the heating element is turned off, the humidity value H is continuously acquired, and the size relation between H and H1 is compared.

and if H is larger than H1, reducing the flow of the bypass pipe, increasing the flow of return air flowing into the freezing chamber from the return air pipe, and then continuously acquiring the humidity value H and comparing the humidity value H with the size relation of H1.

if T is larger than T1, the humidity value H is continuously acquired and the size relation between H and H1 is compared.

Drawings

Fig. 1 is a schematic structural view of an air returning device according to the present embodiment;

fig. 2 is a flowchart illustrating a control method of a refrigerator according to the present embodiment.

Description of reference numerals:

10. an air return device; 11. a return air duct; 111. a return air door; 112. an air return inlet; 113. an air return outlet; 12. a cold air pipe; 121. a mixing pipe section; 122. a cold air mixing damper; 123. a cold air inlet; 124. a cold air outlet; 13. a bypass pipe; 131. a bypass damper; 132. bypassing the mixing damper; 14. a heating member; 15. a drainage channel; 16. a water pan; 17. an evaporator.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

In one embodiment, as shown in fig. 1, a return air device 10 is provided. The air return device 10 can be applied to a refrigerator to control the humidity in a refrigerating chamber and the refrigerating process in an energy-saving manner.

Specifically, as shown in fig. 1, the air returning device 10 includes a return air duct 11, a cold air duct 12, and a bypass duct 13, wherein a return air inlet 112 of the return air duct 11 can communicate with the refrigerating chamber, and a return air outlet 113 of the return air duct 11 can communicate with the freezing chamber. The air conditioner is used for guiding return air with certain humidity in the refrigerating chamber into the freezing chamber. The cold air inlet 123 of the cold air pipe 12 can be communicated with the freezing chamber, and the cold air outlet 124 of the cold air pipe 12 can be communicated with the refrigerating chamber. After the return air entering the freezing chamber from the refrigerating chamber is subjected to low-temperature dehumidification in the freezing chamber, the cold air flows back to the refrigerating chamber from the cold air pipe 12. The bypass pipe 13 is communicated between the return air duct 11 and the cold air duct 12, and is used for guiding the return air part in the return air duct 11 into the cold air duct 12. And the bypass pipe 13 can directly guide part of the return air in the return air pipe 11 into the refrigerating chamber, so that the amount of the return air entering the freezing chamber is reduced. And then adjusting the humidity and the temperature in the refrigerating chamber.

As shown in fig. 1, a position of the cold air pipe 12, which is communicated with the bypass pipe 13, is a bypass inlet, a portion of the cold air pipe 12, which is located between the bypass inlet and the cold air outlet 124, is a mixing pipe segment 121, and the mixing pipe segment 121 is provided with a heating element 14.

The return air with higher humidity and the cold air with lower temperature flowing into the cold air duct 12 from the freezing chamber run into the mixing duct section 121 at the time of mixing, and there is a risk of frost formation. When the temperature in the mixing pipe section 121 is lower than a certain value, the heating element 14 is turned on to achieve the effect of defrosting or avoiding frosting, so that the smoothness of the cold air pipe 12 is guaranteed, and the reliable operation of the refrigeration process and the humidity control in the refrigerating chamber is effectively guaranteed.

Specifically, in one embodiment, the heating element 14 may be disposed on the wall of the cool air duct 12, or the heating element 14 may be disposed in the lumen of the cool air duct 12. As long as the mixing section 121 can be defrosted or frost formation avoided by heating.

Of course, the heating element 14 is arranged on the wall of the cold air pipe 12, so that the mixed air in the mixing pipe section 121 can be prevented from being heated while the frost accumulated on the wall of the cold air pipe 12 is heated and melted. The effects of avoiding frosting and blocking of the cold air pipe 12 and ensuring refrigeration of the refrigerating chamber by mixed air are achieved.

Further, in one embodiment, as shown in FIG. 1, the heating element 14 is disposed at a bypass opening.

The return air in the bypass pipe 13 enters the cold air pipe 12 through the bypass inlet, the condition that the cold air and the return air are mixed and frosted at the bypass inlet is serious, and the heating element 14 is arranged at the bypass inlet, so that the defrosting effect is further improved, and the smoothness of the cold air pipe 12 is guaranteed.

Further, the heating element 14 may be circumferentially disposed at a position on the bypass pipe 13 where the bypass inlet is disposed, so as to further improve the defrosting effect.

Further, in an embodiment, as shown in fig. 1, the air returning device 10 further includes a water drainage channel 15, where the water drainage channel 15 penetrates through a side wall of the cold air duct 12, and is used for guiding out defrosting water in the cold air duct 12. The deposition of defrosted water in the cold air duct 12 or the freezing chamber is avoided.

Specifically, the drainage channel 15 may be a separately provided drainage pipe or a channel formed in a part of the refrigerator, and is not particularly limited herein.

Further, in an embodiment, the inner wall of the cold air pipe 12 is provided with defrosting water collecting tanks, the defrosting water collecting tanks are distributed along the circumferential direction of the inner wall of the cold air pipe 12, the defrosting water collecting tanks are located below the heating element 14, and a water inlet formed on the inner wall after the water drainage channel 15 penetrates through the side wall of the cold air pipe 12 is communicated with the defrosting water collecting tanks.

The heating element 14 flows the heated and melted defrosting water into the defrosting water collecting tank along the inner wall of the cold air pipe 12, and then flows out through the drainage channel 15. The defrosting water collecting tanks distributed circumferentially can effectively collect the defrosting water left along the inner wall of the cold air pipe 12.

Further, in one embodiment, the defrost water collection tank is lower in communication with the water inlet than other portions of the defrost water collection tank. Thereby enabling the defrost water to be efficiently and rapidly discharged from the water inlet.

Further, in an embodiment, as shown in fig. 1, the air returning device 10 further includes a water receiving tray 16, and a water outlet of the drainage channel 15 corresponds to the water receiving tray 16, and is used for guiding defrosting water into the water receiving tray 16. The water melted in the cold air pipe 12 is finally collected in the water pan 16.

Further, in an embodiment, as shown in fig. 1, the number of the return air pipes 11 and the number of the bypass pipes 13 are two, the two return air pipes 11 are respectively located at two sides of the cold air pipe 12, and the bypass pipes 13 are in one-to-one correspondence with the return air pipes 11, so that the return air efficiency is improved.

Moreover, in order to make the overall structure more compact, as shown in fig. 1, the water pan 16 is disposed below the return air duct 11 and the cold air duct 12. And the middle part of the water pan 16 corresponds to the cold air pipe 12, and the middle part of the water pan 16 is sunken downwards to form a collecting area. The dissolved defrosting water is gathered in the collecting area.

Further, in another embodiment, a refrigerator is provided, which includes a refrigerating chamber, a freezing chamber and the above air returning device 10, the air returning inlet 112 of the air returning pipe 11 is communicated with the refrigerating chamber, the air returning outlet 113 of the air returning pipe 11 is communicated with the freezing chamber, the cold air inlet 123 of the cold air pipe 12 is communicated with the freezing chamber, and the cold air outlet 124 of the cold air pipe 12 is communicated with the refrigerating chamber.

By arranging the air returning device 10 in any one of the above embodiments in the refrigerator, when the air returning pipe 11, the bypass pipe 13 and the cold air pipe 12 realize the humidity and temperature control in the refrigerating chamber, the heating element 14 further ensures the reliable performance of the refrigerating process and the humidity control process in the refrigerating chamber.

Further, in one embodiment, the refrigerating chamber is provided with a humidity detector, and the cold air duct 12 is provided with a temperature detector. As shown in fig. 1, a return air door 111 is disposed on the return air pipe 11, the return air door 111 is located on the return air pipe 11 at a position downstream of a position communicated with the bypass pipe 13, a bypass air door 131 is disposed at an inlet of the bypass pipe 13, a bypass air mixing door 132 is disposed at an outlet of the bypass pipe 13, a cold air mixing door 122 is disposed on the cold air pipe 12, the cold air mixing door 122 is located below the bypass inlet, the humidity detection part is electrically connected to the return air door 111, the bypass air door 131, the bypass air mixing door 132 and the cold air mixing door 122, and the temperature detection part is electrically connected to the heating part 14.

When the humidity value detected by the humidity detection member is smaller than the humidity set value, the opening degrees of the return air door 111 and the cold air mixing door 122 are decreased, and the opening degrees of the bypass air door 131 and the bypass mixing door 132 are increased. At this time, if the temperature in the cold air duct 12 detected by the temperature detection part is low, the heating part 14 is started to heat and defrost.

Further, in one embodiment, the temperature sensing member is located in the mixing tube segment 121. The temperature of the mixing pipe section 121 is directly obtained, whether the mixing pipe section 121 frosts or not is judged, and the detection result is more accurate.

Of course, alternatively, the temperature detecting element may also be disposed at other parts of the cold air pipe 12, as long as it can reflect the temperature in the mixing pipe segment 121, and is not limited herein.

Further, as shown in fig. 1, in one embodiment, the refrigerator further includes an evaporator 17, and the evaporator 17 is located between the return air outlet 113 and the cool air inlet 123. The evaporator 17 is used for cooling the freezing chamber, and the return air discharged from the return air outlet 113 flows back to the cold air pipe 12 from the cold air inlet 123 after being cooled in the freezing chamber.

Further, as shown in fig. 2, in yet another embodiment, there is provided a refrigerator control method for controlling the above refrigerator, the refrigerator control method comprising the steps of:

if H is less than H1, increasing the circulation of the bypass pipe 13 and reducing the circulation of the return air flowing into the freezing chamber from the return air pipe 11;

acquiring the temperature T of the pipe wall of the mixing pipe section 121, and comparing the magnitude relation between the temperature T and a temperature set value T1;

if T is less than T1, the heating element 14 is activated.

When the humidity level H in the freezer compartment is less than the humidity set point H1, it is evident that the freezer compartment humidity needs to be increased. Thus increasing the flow rate of the bypass duct 13 and reducing the flow rate of the return air flowing from the return duct 11 into the freezing chamber. And detecting the temperature T of the pipe wall of the mixing pipe section 121, and if the temperature T is less than a set temperature value T1, proving that the temperature of the mixed air of the return air and the cold air mixed in the mixing pipe section 121 is low, so that frosting and risks exist. Therefore, the heating element 14 is started to heat the mixing pipe section 121, so that the effect of defrosting or avoiding frosting is achieved, and the reliable operation of the humidity adjustment and refrigeration process in the refrigerating chamber is guaranteed.

Further, in one embodiment, as shown in FIG. 2, after the heating element 14 has been activated for a time period t1, the heating element 14 is turned off, the humidity value H continues to be obtained and the magnitude relationship between H and H1 is compared. And circulating to the implementation process in the above embodiment, so that the refrigerator control process forms a dynamic process to ensure that the temperature of the mixing pipe section 121 of the cold air pipe 12 is within a proper range.

Further, in one embodiment, as shown in fig. 2, if H is greater than H1, the flow of the bypass duct 13 is reduced, increasing the flow of the return air from the return duct 11 into the freezer compartment. Thereby increasing the humidity in the refrigerating chamber. And then continuously acquiring the humidity value H and comparing the size relation of H and H1 so that the humidity of the refrigerating chamber is maintained within a target range value.

Further, in one embodiment, as shown in fig. 2, the refrigerator control method further includes the steps of:

if T is greater than T1, it is demonstrated that defrosting is not required in the mixing section 121, and therefore the moisture value H continues to be obtained and compared to the magnitude relationship of H to H1. The above process is cycled such that the temperature in mixing section 121 is maintained within the target range of values.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The utility model provides an air return device, its characterized in that, includes return air pipe, cold wind pipe and bypass pipe, the return air entry of return air pipe can communicate with the walk-in, the return air export of return air pipe can communicate with the freezer, the cold wind entry of cold wind pipe can communicate with the freezer, the cold wind export of cold wind pipe can communicate with the walk-in, the bypass pipe intercommunication be in return air pipe with between the cold wind pipe, be used for with the leading-in of return air part in the return air pipe in the cold wind pipe, the position that is the bypass inlet on the cold wind pipe with the bypass pipe intercommunication, the part that lies in on the cold wind pipe bypass entry with between the cold wind export is the mixing pipe section, the mixing pipe section is equipped with the heating member.

2. The air return device of claim 1, wherein the heating element is disposed on a wall of the cold air duct, or the heating element is disposed in a lumen of the cold air duct.

3. The return air device according to claim 1, wherein the heating member is provided at the bypass opening.

4. The air return device according to any one of claims 1 to 3, further comprising a water drainage channel, wherein the water drainage channel penetrates through a side wall of the cold air duct and is used for guiding out defrosting water in the cold air duct.

5. The air return device according to claim 4, wherein the inner wall of the cold air duct is provided with defrosting water collecting tanks, the defrosting water collecting tanks are circumferentially distributed along the inner wall of the cold air duct, the defrosting water collecting tanks are located below the heating element, and a water inlet formed in the inner wall of the cold air duct after the water drainage channel penetrates through the side wall of the cold air duct is communicated with the defrosting water collecting tanks.

6. The return air apparatus according to claim 5, wherein the defrosting water collecting tank is lower in position in communication with the water inlet than other portions of the defrosting water collecting tank.

7. The air return device as claimed in claim 4, further comprising a water pan, wherein the water outlet of the drainage channel corresponds to the water pan and is used for guiding defrosting water into the water pan.

8. The air return device according to claim 7, wherein the number of the return ducts and the number of the bypass ducts are two, the two return ducts are respectively located on both sides of the cold air duct, the bypass ducts correspond to the return ducts one to one, the water pan is located below the return ducts and the cold air duct, the middle portion of the water pan corresponds to the cold air duct, and the middle portion of the water pan is recessed downward to form a collection area.

9. A refrigerator is characterized by comprising a refrigerating chamber, a freezing chamber and the air returning device as claimed in any one of claims 1 to 8, wherein an air returning inlet of the air returning pipe is communicated with the refrigerating chamber, an air returning outlet of the air returning pipe is communicated with the freezing chamber, a cold air inlet of the cold air pipe is communicated with the freezing chamber, and a cold air outlet of the cold air pipe is communicated with the refrigerating chamber.

10. The refrigerator according to claim 9, wherein the refrigerating chamber is provided with a humidity detection member, the cold air pipe is provided with a temperature detection member, the return air pipe is provided with a return air door, the return air door is located at a downstream position of a position on the return air pipe, which is communicated with the bypass pipe, a bypass air door is arranged at an inlet of the bypass pipe, a bypass mixing air door is arranged at an outlet of the bypass pipe, the cold air pipe is provided with a cold air mixing air door, the cold air mixing air door is located below the bypass inlet, the humidity detection member is electrically connected with the return air door, the bypass mixing air door and the cold air mixing air door, and the temperature detection member is electrically connected with the heating member.

11. The refrigerator of claim 10 wherein the temperature sensing member is located in the mixing tube section.

12. The refrigerator according to any one of claims 9 to 11, further comprising an evaporator located between the return air outlet and the cold air inlet.

13. A refrigerator control method for controlling the refrigerator of any one of claims 9 to 12, the refrigerator control method comprising the steps of:

if T is less than T1, the heating element is activated.

14. The control method of the refrigerator according to claim 13, further comprising the steps of:

15. The control method of the refrigerator according to claim 13, further comprising the steps of:

16. The refrigerator control method according to any one of claims 13 to 15, further comprising the steps of: