JP5861033B2 - refrigerator - Google Patents

Description

  The present invention relates to a refrigerator that forcibly circulates cold air generated by a cooler to cool each storage room having a different temperature range.

  FIG. 9 is a longitudinal sectional view of a conventional refrigerator.

  As shown in FIG. 9, the cabinet 1 shows a refrigerator constituted by a heat insulating box 5 filled with a heat insulating material 4 between an inner box 2 and an outer box 3. The refrigerator has a refrigerator compartment 6, a storage compartment 7, and a freezer compartment 8 from above, and a front side is a refrigerator compartment opening / closing door 9, a storage compartment opening / closing door 10, and a freezer compartment opening / closing door 11.

  The refrigerator compartment 6 and the storage room 7 are partitioned by a partition plate 12 having a heat insulation effect, and the storage room 7 and the freezer compartment 8 are partitioned by a partition plate 13 having a heat insulation effect. A duct 14 connected to the freezer compartment 8 is installed in the back of the partition plate 13.

  In the refrigerator compartment 6, a refrigerator compartment shelf for storing food and a refrigerator compartment case are arranged. In addition, a tube-on-sheet 15 (evaporator) is disposed in contact with the wall surface on the back surface of the inner box 2 of the refrigerator compartment 6, and the refrigerator compartment 6 has a cooling wall surface cooled by the tube-on-sheet 15. It has become. A cooler 16 is disposed on the back of the freezer compartment 8, and a fan 17 is disposed above the cooler 16.

  In addition, the inside of the warm room 7 has a warm room for storing food, and a duct 18 having a damper 19 inside is disposed on the back side.

  About the refrigerator comprised as mentioned above, the operation | movement is demonstrated below.

  As for cooling of the refrigerator compartment 6, the tube-on-sheet 15 is in contact with the back surface of the inner box 5 of the refrigerator compartment 6, and the inner box 5 surface of the refrigerator compartment 6 serves as a cooling wall, and the refrigerator compartment in the refrigerator compartment 6 is naturally cooled. Cooling of shelves and refrigerator compartment cases.

  On the other hand, the cooling of the freezer compartment 8 is performed by forcibly circulating the cool air of the cooler 16 in the cooling chamber by the fan 17 to cool the inside of the freezer compartment 8. The cold air circulated in the freezer compartment 8 returns to the cooler 16.

  Further, the cooling of the warming chamber 7 is partly cooled by the fan 17 and flows into the duct 14 and circulates to the duct 18 on the back of the warming chamber 7. The cold air that has flowed into the duct 18 passes through the damper 19, is discharged into the greenhouse case, exchanges heat with the air in the chamber, and is then sucked into the return duct to the cooler 16 on the back surface. Returned to

  As described above, in the present embodiment, the refrigerating room 6 and the storage room 7 do not form a passage through which the cold air is circulated by the partition plate 12, but are partitioned vertically, and the refrigerating room 6 is formed by cooling the tube-on-sheet 15. Cooling to an appropriate temperature, the warming chamber 7 circulates the latent heat of vaporization of the cooler 16 into the warming chamber 7 by the fan 17, and further controls the amount of cold air circulated by a damper that detects the temperature of the warming chamber 7. Thus, by keeping the temperature of the temperature-preserving chamber 7 constant, it becomes possible to keep the temperature of the food in the temperature-holding case constant, and the freshness of the food can be improved. (For example, refer to Patent Document 1).

JP 2005-195293 A

However, in the above-described conventional configuration, the air path is not configured in the refrigerator compartment 6, and the temperature difference inside the chamber tends to be large between a location close to the tube-on-seat 15 and a location far away.
In addition, in order to cool the inside of the thermal storage room 7 uniformly, cold air is discharged from a plurality of outlets 20 provided on the side of the thermal storage room 7, so that there is a dew condensation problem around the outlet 20 due to the temperature difference between the thermal storage room 7 and the cold air. There was a concern that it was likely to occur.
This invention solves the said conventional subject, and it aims at preventing the equalization | homogenization of the temperature in a refrigerator compartment and dew condensation, comprising the duct provided also with the cold air path which cools a refrigerator compartment on the back. .

  In order to solve the above-described conventional problems, a refrigerator according to the present invention includes a refrigerator compartment, a freezer compartment, a partition wall that insulates between the refrigerator compartment and the refrigerator compartment, and cool air behind the refrigerator compartment. Refrigeration having a cooler to be generated and a cooling chamber having a fan that is disposed above the cooler and forcibly blows the generated cool air to each chamber, and blows cool air to the refrigerating chamber by the fan A refrigerator having a room air duct and a duct device having a refrigerating room return duct for returning cold air discharged into the refrigerating room to the cooler, and a discharge port provided in the refrigerating room air duct Since the cross-sectional area of the discharge opening on the inside of the warehouse is larger than the minimum cross-sectional area in the discharge air passage, the air passage cross-sectional area of each can prevent the temperature in the refrigerator compartment from being uniform and prevent condensation. Uniform storage room temperature, reliability around duct device It can be ensured.

  The refrigerator of this invention can provide the refrigerator which improved the cooling efficiency and secured the reliability of the duct apparatus by improving the discharge port structure of the duct apparatus which ensures uniformity of each store room temperature.

The longitudinal cross-sectional view of the refrigerator in Embodiment 1 of this invention The front view of the main body in Embodiment 1 of this invention Main part schematic in Embodiment 1 of this invention The perspective view of the refrigerator compartment duct apparatus in Embodiment 1 of this invention The exploded view of the refrigerator compartment duct apparatus in Embodiment 1 of this invention The perspective view of the refrigerator compartment back part in Embodiment 1 of this invention Sectional drawing of the discharge port of the refrigerator compartment duct apparatus in Embodiment 1 of this invention Sectional drawing of the discharge port of the refrigerator compartment duct apparatus in Embodiment 2 of this invention Cross-sectional view of a conventional refrigerator

  A first invention includes a refrigerator compartment, a freezer compartment, a partition wall that thermally insulates between the refrigerator compartment and the freezer compartment, a cooler that generates cool air behind the freezer compartment, and A cooling room having a fan forcibly blowing the generated cold air to each room, and a cooling room air duct for blowing cold air to the refrigerating room by the fan, and the inside of the refrigerating room A refrigerator having a refrigerating room return duct for returning the cold air discharged to the cooler, wherein the airflow cross-sectional area of the discharge port provided in the refrigerating room air duct is a discharge airflow path The cross-sectional area of the discharge opening inside the warehouse is larger than the minimum cross-sectional area inside.

This makes it possible to configure the mating surface of the mold when molding the discharge air passage of the refrigeration room air duct on the back side of the discharge air passage that is difficult to see from the storage room, and prevent quality condensation by preventing condensation due to heat insulation. A duct device having a discharge port that ensures the appearance quality at the same time as securing can be obtained.

  According to a second aspect of the present invention, the duct device includes a decorative plate formed of a resin member on the surface of the refrigeration chamber air duct, thereby improving strength that is insufficient only with the decorative plate heat insulating member. In addition, the degree of freedom in color and shape is increased, and the design in the storage room visible to the customer can be improved.

  According to a third aspect of the present invention, the decorative plate has a cross-sectional area larger than the minimum cross-sectional area of the cross-sectional area in the air passage of the discharge port provided in the refrigerating chamber air duct. The decorative board is cooled from the back surface, so that condensation on the surface of the decorative board due to a temperature difference in the storage chamber can be prevented and quality reliability can be ensured.

  According to a fourth aspect of the present invention, the outlet of the refrigeration chamber air duct is provided with an R molding surface at the opening on the refrigeration chamber side, thereby improving the molding accuracy of the heat insulating member so as to be visible from the storage chamber. Unevenness on the surface can be suppressed, and the quality of the duct device can be improved.

  According to the fifth aspect of the present invention, since the discharge port of the refrigeration chamber air duct is disposed at a height of 1 m or more from the floor surface, the discharge port is disposed at a height that can easily enter the customer's field of view. The effect of the discharge port that balances the quality and quality can be exhibited more.

  According to a sixth aspect of the present invention, the discharge port of the refrigerator compartment air duct has a cross-sectional area larger than a minimum cross-sectional area portion of the discharge air passage on the air passage side, so The air path resistance of the cold air flowing into the discharge port can be reduced, and the efficiency of the air path circulation of the cold air can be improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are given to the same configurations as those of the conventional example or the embodiments described above, and detailed descriptions thereof will be omitted. The present invention is not limited to the embodiments.

(Embodiment 1)
1 is a longitudinal sectional view of a refrigerator according to Embodiment 1 of the present invention, FIG. 2 is a front view of a main body according to Embodiment 1 of the present invention, and FIG. 3 is a schematic diagram of a main part according to Embodiment 1 of the present invention. 4 is a perspective view of the refrigerating chamber duct apparatus according to the first embodiment of the present invention, FIG. 5 is an exploded view of the refrigerating chamber duct apparatus according to the first embodiment of the present invention, and FIG. 6 is the refrigeration according to the first embodiment of the present invention. A first perspective view of the room, FIG. 7 is a cross-sectional view of the discharge port of the refrigerator compartment duct device according to Embodiment 1 of the present invention.

  In FIG. 1, a heat insulating box 31 of a refrigerator 30 is mainly composed of an outer box 32 using a steel plate and an inner box 33 formed of a resin such as ABS, and inside thereof, for example, a foam insulation such as hard foam urethane. The material 34 is filled and insulated from the surroundings, and is divided into a plurality of storage chambers. The refrigeration chamber 35 is disposed at the top, the switching chamber 36 is disposed below the refrigeration chamber 35, and the freezing chamber 37 is disposed at the bottom.

  The refrigerator compartment door 38 opens and closes the front opening of the refrigerating room 35, the switching room door 39 opens the front opening of the switching room 36, and the freezing room door 40 opens and closes the front opening of the freezing room 37. It is freely pivoted.

The refrigeration chamber 35 is normally set to 1 ° C. to 5 ° C. at the lower limit of the temperature at which it does not freeze for refrigerated storage, and the switching chamber 36 can be set to change the temperature from the refrigeration temperature zone to the refrigeration temperature zone. Can be set at intervals. The freezer compartment 37 is set to a freezing temperature zone, and is usually −
Although it is set at 22 ° C. to −15 ° C., it may be set at a low temperature such as −30 ° C. or −25 ° C. in order to improve the frozen storage state.

  Further, the switching chamber 36 and the freezing chamber 37 are vertically partitioned by the first partition wall 41, and the refrigerator compartment 35 and the switching chamber 36 are vertically partitioned by the second partition wall 42.

  A cooling chamber 43 for generating cool air is provided on the back of the freezing chamber 37, and a cooler 44 is provided inside. The cooling chamber 43 is insulated from the freezing chamber 37 by a cover coil 45. A fan 46 that forcibly blows cool air generated above the cooler 44 is disposed, and a defrost heater 47 that defrosts frost and ice adhering to the cooler 44 is provided below the cooler 44. Yes. Specifically, the defrost heater 47 is a glass tube heater made of glass, and in particular, when the refrigerant is a hydrocarbon-based refrigerant gas, a double glass tube heater in which glass tubes are formed in a double manner is adopted for explosion protection. Has been. Further, the cover coil 45 is formed of a resin decorative plate 45a and an inner cover coil 45b in which a holding portion of the fan 46 and a cold air passage are formed by a heat insulating material such as a styrene material.

  In addition, a duct device 49 having a cooling duct 35 and a blower duct 48 for blowing cool air to the switching chamber 36 is provided on the back surface of the switching chamber 36. The air duct 48 has a refrigerating room air duct 48a for sending cool air to the refrigerating room 35 and a switching room air duct 48b for sending cold air to the switching room 36, which are arranged side by side in the duct device 49 side by side in the vertical direction. ing. In the duct device 49, a damper device 50 for adjusting the amount of cold air to the refrigeration chamber 35 and the switching chamber 36 is embedded, and is disposed in each of the refrigeration chamber air duct 48a and the switching chamber air duct 48b and passes therethrough. The amount of cold air is controlled separately.

  The cold air discharged from the discharge port 35a of the refrigerating chamber 35 through the refrigerating chamber air duct 48a returns to the cooler 44 through the refrigerating chamber return duct 51a from the return port 35b provided on the lower back surface of the refrigerating chamber 35. The cold air discharged to the switching chamber 36 through the switching chamber air duct 48b returns to the cooler 44 from the switching chamber return port 36c provided in the lower part of the duct device through the switching chamber return duct 51b on the back surface of the switching chamber 36. To do.

  The refrigerating room return duct 51a is arranged side by side with the air duct 48, whereby three ducts of the refrigerating room air duct 48a, the switching room air duct 48b, and the refrigerating room return duct 51a are arranged vertically in the duct device 49. They are arranged side by side. The switching chamber return duct 51b is arranged next to the refrigerator compartment return duct 51a in the front-rear positional relationship, and the switching chamber return duct 51b is arranged in front of the refrigerator compartment return duct 51a.

  The duct device 49 is formed to have a large rear surface height and lateral width dimensions of the switching chamber 36, and the refrigeration chamber air duct 48 a and the switching chamber air duct 48 b are approximately in the center in the lateral width direction of the switching chamber 36, that is, the width direction of the duct device 49. The refrigerating room return duct 51a and the switching room return duct 51b are collectively arranged on one side of the duct device 49 centering on the refrigerating room air duct 48a and the switching room air duct 48b.

  The cover coil 45 is provided side by side with the cooler 44 and is formed with a cool air return passage 71 partitioned by the cooler 44, the partition member 75, and the back wall of the cooling chamber 43. Cold air that has passed through the refrigerator compartment return communication port 58 and the switching chamber return communication port 59 of the wall 41 is introduced.

  Next, the refrigerator compartment 35 will be described.

The refrigerator compartment 35 is divided into a plurality of upper and lower compartments by a plurality of shelves 61, and the refrigerator compartment air duct 48 a configured on the back surface of the refrigerator compartment 35 is formed in the vertical direction behind the plurality of shelves 61 and corresponds to each shelf 61. The refrigerator discharge port 62 is open. The refrigerating room air duct 48a may be formed with a branch path 63 that branches left and right in the space of the refrigerating room 35. By providing the branch path 63, the temperature distribution in the space in the width direction of the refrigerating room 35 is made uniform. can do.

  The refrigerator compartment duct device 80 is disposed on the back surface of the refrigerator compartment 35, and the refrigerator compartment duct device 80 and the inner box 2 form an air path of the refrigerator compartment. Further, the refrigerating room 35 and the switching room 36 are coupled to a second partition wall 42 that vertically divides the refrigerating room, and the refrigerating room discharge cool air and return cold air are circulated from the cooling room 43 through the duct device 49 of the switching room 36. The temperature range is 35.

  The refrigerator compartment duct device 80 is formed of a refrigerator compartment duct member 81 formed of foamed polystyrene and a resin refrigerator compartment duct decorative plate 86 that covers the front surface of the refrigerator compartment duct member 81, and is attached to a seal portion of the refrigerator compartment duct device 80. A seal foam member 82 is attached.

  Further, the partition wall duct member 87, the partition wall plate member 88, and the foam member seal portion 84 of the inner box 2 in which the lower surface portion and the rear surface portion of the refrigerator compartment duct member 81 are the upper surface portions of the second partition wall 42 are sealed foam members. By compressing 82 and closely adhering to it, a seal strengthening structure is formed at the seal connecting portion of the refrigerator compartment duct device 80, the seal connection is made in the vertical direction and the front-rear direction, and the refrigerator compartment which is the back portion of the refrigerator compartment duct member 81 The duct pressure contact seal portion 83a is connected to the inner box pressure contact seal portion 83b of the inner box 2 in a seal connection, and the front surfaces thereof are covered with the refrigerator compartment duct decorative plate 86.

  In order to make the temperature of the refrigerator compartment 35 uniform, the shape of the refrigerator compartment duct press-contact seal portion 83a of the refrigerator compartment duct member 81 is uneven, and cool air is discharged so as to wrap the entire refrigerator compartment. Refrigeration chamber duct pressure contact seal portion 83a and seal foam member 82 for sealing structure foam member seal portion 84 switching is not connected on the same line, but each seal portion is arranged in parallel and then switched by wrapping in parallel. A sufficient contact distance can be ensured between parts, and variations in parts and assembly can be absorbed, so that the sealing performance can be improved.

  Further, by emphasizing that the inner box pressure seal part 83b of the inner box 2 is provided with a step and is different from the peripheral part, it is easy to ensure the planar accuracy of the seal part at the time of molding the mold, and the refrigerator compartment pressure welding is performed. It is possible to improve the sealing performance by contact with the seal portion 83a.

  In addition, although the seal reinforcement structure was demonstrated with the form of the refrigerator compartment, you may use these seal reinforcement structures also in a switching chamber like a refrigerator compartment.

  Further, the refrigerator compartment duct member 81 has cold air from the measuring portion discharge opening 91 that performs cold air circulation that goes around the inside of the refrigerator chamber 35 from the side surface, and an upper discharge opening 92 that performs cold air circulation that blows down from the top. Have. Further, a duct device discharge port 90 is provided in front of the refrigerator compartment duct decorative plate 86 which is the surface of the refrigerator compartment duct member 81.

  Further, a control board 66 for controlling the entire refrigerator 30 is arranged at a position corresponding to the back surface of the switching chamber 36 in the outer box 32.

  A refrigerator temperature sensor 67 for detecting the temperature of the refrigerator compartment 35 is installed in the refrigerator compartment return port 35b, and a switching chamber temperature sensor 68 for detecting the temperature of the switching chamber 36 is installed in the switching chamber return port 36c. .

  About the refrigerator comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

A part of the cold air generated by the cooler 44 in the cooling chamber 43 is forcibly blown forward by the fan 46, the freezing chamber 37 is cooled by the cold air discharged from the discharge port of the cover coil 45, and the cold air is covered by the cover coil 45. The air is guided to the lower part of the cooler 44 through a return port opened at the lower part of the heat exchanger, heat exchanged by the cooler 44, and fresh cold air is again circulated by the fan 46. As a result, the freezer compartment 37 is cooled to an appropriate temperature under the control of the freezer sensor.

  The cool air discharged above the fan 46 is guided from the cool air discharge port 72 of the cover coil 45 through the communication hole of the first partition wall 41 to the duct device 49. When the room temperature is equal to or higher than the set temperature by the cold room temperature sensor 67, the cold air discharged to the cold room 35 opens the cold room damper 50a of the damper device 50, passes through the cold room air duct 48a, and discharges the cold room. Cold air is discharged from 35a to cool the room. The circulated cold air is guided to the return port 35b, becomes air having moisture contained in the air in the refrigerating chamber 35 and the stored material, passes through the refrigerating chamber return duct 51a of the duct device 49, and the cover coil 45 and the cooling chamber. Through the cool air return passage 71 constituted by the back wall 43 of the gas 43, the cool air return port 77 leads to the lower part of the cooler 44 to exchange heat with the cooler 44, and fresh cool air is forcibly blown by the fan again. Is done.

  Thus, even if the refrigerator compartment 35 is located away from the cooler 44, the fan 46 forcibly blows cool air to the refrigerator compartment air duct 48 a communicating with the cooler 44, and the refrigerator compartment air duct in the duct device 49 is forced. Cold air is discharged to the refrigerating room 35 through 48a, and the opening and closing of the refrigerating room damper 50a is controlled by the refrigerating room temperature sensor 67, so that the room can be controlled to the set temperature.

  In addition, cooling of the refrigerating chamber 35 is performed by enclosing the inside of the refrigerating chamber 35 with cold air from the side surface side and from the upper surface by the measuring portion discharge opening 91 and the upper discharge opening 92 provided in the refrigerating chamber duct member 81. Cool down. Further, since the cool air discharge to the front is also performed by the duct device discharge port 90 provided in front of the refrigerator compartment duct decorative plate 86, the vicinity of the refrigerator compartment duct member 81 can be cooled, and the temperature in the refrigerator compartment 35 is uniform. Can be achieved.

  Since the difference between the cold air discharged from the duct device discharge port 90 and the temperature in the refrigerator compartment 35 is large, the duct member discharge port 90a and the duct decorative plate discharge port 90b have the same hole size (that is, the discharge shown in FIG. 7). In the cross section of the outlet, the minimum dimension [A] of the discharge port cross section [B] = the size of the opening on the storage chamber side [B] = the discharge port opening size [C] of the duct decorative plate discharge port 90b) Since the end face of the molded duct decorative plate discharge port 90b is also cooled, condensation occurs on the surface of the refrigerator compartment duct decorative plate 86.

  In order to solve this dew condensation problem, the minimum dimension [A] of the discharge port cross section <the opening size [B] of the storage chamber side, and the minimum dimension [A] of the discharge port cross section <the discharge port opening dimension [C]. It is necessary to satisfy the conditions. At this time, it is preferable that [B] <[C], but this is not an absolute condition when the duct decorative plate discharge port 90b is not cooled by the flow state of the cold air. Further, as a structure that can be easily molded by a mold, it is common that the minimum dimension [A] of the discharge port cross section is on the wall surface in the air passage.

  The shape of the opening on the storage chamber side of the duct member discharge port 90a is desirably rounded. The refrigerator compartment duct member 81 is formed of a foam heat insulating member such as foamed polystyrene, and the end face shape is R-shaped, so that the foam beads can be reliably solidified at the end face. As a result, the shape of the foam heat insulating member that can be seen from the discharge port looks beautiful, so that the appearance quality of the refrigerator compartment can be improved. The R shape of the opening on the storage chamber side of the duct member discharge port 90a is preferably 3R or more in order to ensure moldability.

In the present invention, the refrigerating chamber duct device 80 of the refrigerating chamber 35 has been described. However, the refrigerating chamber duct device 80 may be used in all the storage chambers where there is a temperature difference between the storage chamber temperature and the discharge cold air and the surface of the duct device may cause condensation. .

(Embodiment 2)
FIG. 8 is a cross-sectional view of the discharge port of the refrigerator compartment duct device according to Embodiment 2 of the present invention.

  As described in FIG. 7 of the first embodiment, the minimum dimension [A] of the discharge port cross section <the opening size [B] of the storage chamber side, and the minimum dimension [A] of the discharge port cross section <the discharge port opening size. By satisfying the condition [C], condensation is prevented from occurring on the surface of the refrigerator compartment duct decorative plate 86. The shape of the opening on the storage chamber side of the duct member discharge port 90a is desirably rounded.

  Further, by setting the minimum dimension [A] of the discharge port cross section <the air path side opening dimension [D] in the middle of the discharge port cross section, the air path resistance of the cold air flowing into the discharge port can be reduced. Further, the end surface on the air passage side opening side is also formed in an R shape, so that the air passage resistance can be further reduced.

  As described above, the refrigerator according to the present invention can also be applied to household or commercial refrigerators.

DESCRIPTION OF SYMBOLS 30 Refrigerator 35 Refrigeration room 36 Switching room 37 Freezing room 41 1st division wall 44 Cooler 45 Cover coil 46 Fan 47 Defrost heater 48 Air blow duct 49 Duct apparatus 50 Damper apparatus 71 Return passage 80 Refrigeration room duct apparatus 81 Refrigeration room duct member 82 Seal foam member 83a Refrigeration room duct pressure seal part 83b Inner box pressure seal part 84 Foam member seal part 86 Refrigeration room duct decorative plate 90 Duct device discharge port 90a Duct member discharge port 90b Duct decorative plate discharge port

Claims (6)

A refrigerator compartment, a freezer compartment, a partition wall that insulates between the refrigerator compartment and the freezer compartment, a cooler that generates cool air behind the freezer compartment, and an upper part of the cooler. A cooling chamber having a fan that forcibly blows the cool air to each chamber, and a cooler chamber air duct that blows cool air to the refrigerating chamber by the fan, and cool air discharged into the refrigerating chamber. A refrigerator having a duct device having a refrigerating room return duct for returning to the cooler,
The refrigerator characterized in that the cross-sectional area of the discharge opening provided inside the refrigerator is larger than the cross-sectional area of the discharge opening provided in the refrigerator air duct. The refrigerator according to claim 1, wherein the duct device includes a decorative board formed of a resin member on a surface of the refrigeration room air duct. The said decorative board provided the discharge port which has a cross-sectional area larger than the minimum cross-sectional area part of the air path cross-sectional area of the discharge port provided in the said refrigerator compartment air duct. Refrigerator. The refrigerator according to any one of claims 1 to 3, wherein the discharge port of the refrigerating room air duct has an R-shaped surface at an opening on the refrigerating room side. The refrigerator according to any one of claims 1 to 4, wherein the refrigerating room air duct discharge port is disposed at a height of 1 m or more from the floor surface. The refrigerator according to any one of claims 1 to 5, wherein the refrigerator compartment air duct discharge port has a cross-sectional area of a discharge opening on the air passage side larger than a minimum cross-sectional area portion in the discharge air passage.