TWI409419B - Bathroom with heating ventilation fans - Google Patents

Abstract

A warming and ventilation fan for bathroom includes: a ventilation fan frame, a snail-shaped housing that is provided with fan blades and a motor, an air flow switching board, and a heater, wherein a structure for preventing air leakage is installed between the snail-shaped housing and an air-flow path. The advantages of the present invention is to ensure the existence of a gap that allows smooth rotation of the air flow switching board, while ensuring flowrate and reducing noise.

Description

Bathroom heating fan

The present invention relates to a heating ventilating fan for a bathroom, and more particularly to an air leakage preventing structure for a heating ventilating fan for a bathroom.

As shown in FIG. 1, a heating ventilating fan 100 for a bathroom includes a frame 110 having an opening 102 connected to the indoor opening and a joint, a blade 120, a motor 130, a heater 140, and a wind circuit switching plate 150. When the heating ventilating fan 100 is operated, the wind is sucked from the air inlet 160 of the heating ventilating fan 100, and then passes through the air passage switching plate 150 to realize the heating, ventilation, and drying functions of the heating ventilating fan 100 by the rotation of the air passage switching plate 150. Select.

Since the air passage switching plate 150 needs to be rotated to achieve the above-mentioned function selection, in this case, a certain gap 180 needs to be ensured between the air passage switching plate 150 and the air passage wall 170, so that the air passage switching plate 150 can be smoothly rotated. In this case, when the heating ventilating fan 100 is operated, a small portion of the wind blows into the gap 180, causing loss of air volume, and noise is generated; however, if there is a gap between the air passage switching plate 150 and the surrounding air passage wall 170 When the setting of the heating ventilator is too small, when the heating ventilating fan is operated, when the wind blows into the gap, a noise may occur or the wind path switching plate 150 may not be flexibly rotated.

It is an object of the present invention to provide a heating ventilating fan for a bathroom which can reduce noise.

In order to achieve the above object, the present invention provides a heating ventilating fan for a bathroom, comprising: a ventilating fan frame, a snail shell provided with a fan blade and a motor, a wind disposed downstream of the snail shell air outlet and capable of switching at least two directions of the wind path The road switching plate, the heater, and the like, wherein the snail shell air outlet is provided with an air leakage preventing structure for guiding the air into the air passage switching plate.

The air leakage preventing structure is a tab protruding from the air outlet of the snail shell to the air passage switching plate, and the air passage switching plate has a rotating piece overlapping the outer side of the tab.

The air passage wall forming the air passage is extended from the air outlet of the snail shell, and the tab is formed between the downstream side of the air outlet of the snail shell and the air passage wall of the air passage to accommodate the air passage switching plate rotor Interval.

The tab is disposed around the entire air outlet of the snail shell.

The tab protrudes from a position of the air passage switching plate that is located above the rotating shaft of the snail shell air outlet.

The tab is protruded from a position lower than a rotating shaft of the air passage switching plate that traverses the snail shell air outlet.

The air leakage preventing structure refers to a plurality of ribs that can be engaged with each other on the air passage switching plate and the air passage wall.

The ribs are respectively disposed on the left and right sides of the air passage switching plate and the air passage wall, and the ribs on the air passage switching plate and the ribs on the air passage wall can be engaged with each other.

A first rib and a second rib are respectively disposed on the sides of the right and left sides adjacent to the air passage switching plate and the air passage wall, and the third rib is disposed at a middle portion of the left and right sides of the air passage wall.

A first rib and a second rib are respectively disposed on the front end and the rear end of the air passage switching plate adjacent to the air passage wall, and a third rib is disposed at a middle portion of the air outlet side of the air passage wall.

Further, a fourth V-shaped fourth rib is disposed on a top surface side of the air passage wall, and a lowest point of the first rib at the front end of the air passage switching plate is higher than a fourth V-shaped fourth rib of the air passage switching plate lowest point.

An advantage of the present invention is that air volume and noise reduction can be ensured while ensuring a gap required for smooth rotation of the air passage switching plate.

2A, 2B, and 2C are schematic views showing a first embodiment of the present invention. As shown in FIG. 2A, the utility model relates to a heating ventilating fan 100 for a bathroom, comprising: a ventilating fan frame 110, a snail shell 131 provided with a blade 120 and a motor 130, an air passage switching plate 150, a heater 140, and the like, and the snail shell 131 has an air outlet. 132. The air outlet 132 is a square tubular shape surrounded by a top wall, a side wall and a bottom wall. The bathroom heating ventilating fan 100 has an air passage from the air outlet 132 to the air outlet 111 of the ventilating fan provided on the side wall of the ventilating fan frame 110, and a wind from the air outlet 132 to the air outlet 112 provided to the ventilating fan mask to be blown into the room. road.

The air passage switching plate 150 has a rotating shaft 151 traversing the snail shell air outlet 132 as shown in FIG. 2B, and a rotating main shaft 151 is provided with a main board 152 for switching the air path and a side plate for continuously rotating the main board 152 to the rotating shaft. 154 of the rotor 155. Further, the air passage switching plate 150 flows down the air outlet 132 of the snail shell 131, and the air outlet is switched to two directions, that is, the above two air passages, according to the position of the main board 152. The air outlet 132 of the snail shell 131 is provided with air toward The air leakage prevention structure guided in the air passage switching plate.

The air leakage preventing structure shown in FIG. 2B is a tab 200 projecting from the periphery of the entire air outlet 132 of the snail shell 131 to the air passage switching plate 150, and the rotor 155 of the air passage switching plate 150 and the tab 200 The outer sides overlap.

The air passage wall 170 forming the air passage extends from the air outlet 132 of the snail shell 131 to the air outlet 111 of the ventilating fan and the air outlet 112 that is blown into the room, and the tab 200 is on the downstream side of the air outlet 132 of the snail shell 131. A constant space 190 for accommodating the air passage switching plate 150 rotor 155 is formed between the air passage wall 170 and the air passage wall 170.

The tab 200 protrudes from the periphery of the entire air outlet 132 toward the inner side of the air passage to form a "mouth" shape. Moreover, the "mouth" shape is divided into upper and lower portions by the rotation axis 151 of the air passage switching plate 150 as described above, and the portion near the top surface 134 of the snail shell 131 is the upper end 210 of the tab 200, which is close to the snail 131. The portion of the bottom surface 135 of the shell is the lower end 220 of the tab 200.

The heating fan ventilator 100 for the bathroom realizes the selection of the heating, ventilation, and drying functions of the heating ventilating fan 100 by controlling the rotational position of the air passage switching plate 150.

As shown in FIG. 2A, a cross-sectional view of the heating ventilating fan 100 for the bathroom in the heating mode is controlled by the stepping motor, and the air passage switching plate 150 is turned to the top surface 134 side of the snail shell 131, and both sides of the air passage switching plate 150 are The side plate 154 and the front end portion 1521 of the main plate 152 are caught in the space 190 between the upper end 210 of the tab 200 and the air passage wall 170 from the downstream side of the air outlet 132. That is, the upper end 210 of the fin 200 and the air passage wall 170 are configured to receive the side wall 154 on both sides of the air passage switching plate 150 and the front end portion 1521 of the main plate 152. Heating ventilator 100 is running At this time, the wind is sucked from the air inlet 160 of the heating ventilating fan, passes through the blade 120, and is blown out from the air outlet 132 of the snail shell 131, and is blown toward the heater 140. With the above configuration, it is possible to prevent the wind from directly flowing out from the gap between the air passage switching plate 150 and the air passage wall 170.

That is, the fin 200 is protruded from the downstream side of the snail shell 131, and the outer side of the tab 200 overlaps with the air passage switching plate 150 to form a housing structure, and the air blown from the snail shell 131 does not leak to the air passage switching plate 150. The outer side is guided to the air passage switching plate 150, and finally can flow to the air passage which is one of the two air passages and blows toward the air outlet 112 in the room.

As shown in FIG. 2C, a cross-sectional view of the heating ventilating fan 100 for the bathroom in the ventilation mode is controlled by the stepping motor, and the air passage switching plate 150 is turned to the bottom surface 135 of the snail shell 131, and the side plates on both sides of the air passage switching plate 150. The 154 and rear end portions 1522 are engaged from the downstream side of the air outlet 132 into the space 190 between the lower end 220 of the "mouth" shaped tab 200 and the air passage wall 170. That is, the lower end 220 of the tab 200 and the air passage wall 170 are configured to receive the side walls 154 on both sides of the air passage switching plate 150 and the rear end portion 1522 of the main plate 152. When the heating ventilating fan 100 is operated, the wind is sucked from the air inlet 160 of the heating ventilating fan, passes through the blade 120, and is blown out from the air outlet 132 of the snail casing 131, and is blown toward the air outlet 111. With the above configuration, it is possible to prevent the wind from directly flowing out from the gap between the air passage switching plate 150 and the air passage wall 170.

That is, the fin 200 is protruded from the downstream side of the snail shell 131, and the outer side thereof overlaps with the lower end 220 of the air passage switching plate 150 to form a housing structure, and the air blown from the snail shell 131 does not leak to the air passage switching plate 150. On the outside, it is guided into the wind switchboard 150, and finally can flow as two winds. The wind path of the air outlet 111 of the ventilating fan of one of the roads.

As described above, when the air passage switching plate 150 rotates, there is a certain gap in the portion in contact with the air passage wall 170, and the air leakage preventing structure, that is, the "mouth" is provided between the air outlet 132 of the snail shell 131 and the air passage. The zigzag tab 200 covers the gap between the air passage switching plate 150 and the air passage wall 170 from the upstream side of the wind, and prevents the wind from being blown into the gap between the air passage switching plate 150 and the air passage wall 170, thereby preventing noise. The generation and prevention of the poor rotation of the air passage switching plate 150 and the effect of ensuring the air volume are achieved. Thereby improving product performance and energy utilization efficiency.

3A and 3B are schematic views showing a second embodiment of the present invention. The air passage wall 170 is extended on the downstream side of the air outlet 132 of the snail shell 131, and the tab 300 projecting downward from the air outlet 132 of the snail shell 131 forms a constant space 290 with the inner side of the air passage wall 170.

The tab 300 is disposed on the upper side of the rotating shaft 151 of the air passage switching plate 150 of the air outlet 132 of the snail shell 131. That is, an inverted "U" shape is formed.

Further, at a certain rotational position, the air passage switching plate 150 is accommodated by the space 290 formed between the outer side of the tab 300 and the air passage wall 170.

As shown in FIG. 3A, a cross-sectional view of the heating ventilating fan 100 for the bathroom in the heating mode is controlled by the stepping motor, and the air passage switching plate 150 is turned to the top surface 134 side of the snail shell 131, and both sides of the air passage switching plate 150 are The side plate 154 and the front end portion 1521 of the main plate 152 are engaged from the downstream side of the wind into the space 290 between the inverted U-shaped tab 300 and the air passage wall 170, and the tab 300 and the air passage wall 170 form a storage air passage switch. The side plates 154 on both sides of the board 150 and the front end portion 1521 of the main board 152 are constructed. When the heating ventilating fan 100 is running, the wind is ventilated from the heating ventilating fan 100 The air inlet 160 is sucked, passes through the blade 120, and is blown out from the air outlet 132 of the snail shell 131, and is blown toward the heater 140. With the above configuration, it is possible to prevent the wind from directly flowing out from the gap between the air passage switching plate 150 and the air passage wall 170.

That is, the fin 300 is protruded from the downstream side of the snail shell 131, and the outer side thereof overlaps with the air passage switching plate 150 to form a housing structure, and the air blown from the snail shell 131 is not leaked, but is guided to the air passage switching. In the plate 150, finally, it is possible to flow to the air passage which is one of the two air passages and blows to the air outlet 112 of the room. Thereby improving product performance and energy utilization efficiency.

4A and 4B are schematic views showing a third embodiment of the present invention. The air passage wall 170 is extended on the downstream side of the air outlet 132 of the snail shell 131, and the fin 400 projecting downward from the air outlet 132 of the snail shell 131 forms a constant space 390 with the inner side of the air passage wall 170.

The tab 400 is disposed on the lower side of the rotating shaft 151 of the air passage switching plate 150 of the air outlet 132 of the snail shell 131. That is, a "U" shape is formed.

Further, at a certain rotational position, the air passage switching plate 150 is accommodated by the space 390 formed between the outer side of the fin 400 and the air passage wall 170.

4A is a cross-sectional view of the heating ventilating fan 100 for the bathroom in the ventilation mode, controlled by the stepping motor, the air passage switching plate 150 is turned to the bottom surface 135 side of the snail shell 131, and both sides of the air passage switching plate 150 The side plate 154 and the rear end portion 1522 are inserted into the space 390 between the U-shaped tab 400 and the air passage wall 170 from the downstream side of the wind, and the tab 400 and the air passage wall 170 form both sides of the air passage switching plate 150. The structure of the side plate 154 and the rear end portion 1522. When the heating ventilating fan 100 is operated, the wind is sucked from the air inlet 160 of the heating ventilating fan 100, passes through the blade 120, and is blown out from the air outlet 132 of the snail casing 131, and is blown toward the air outlet 111. With the above configuration, it is possible to prevent the wind from directly flowing out from the gap between the air passage switching plate 150 and the air passage wall 170.

That is, the fin 400 is protruded from the downstream side of the snail shell 131, and the outer side thereof overlaps with the air passage switching plate 150 to form a housing structure, and the air blown from the snail shell 131 is not leaked but is guided to the air passage switching. In the panel 150, finally, it can flow to the air passage of the air outlet 111 of the ventilating fan which is one of the two air passages. Thereby improving product performance and energy utilization efficiency.

5A, 5B, 5C, and 5D are schematic views of a fourth embodiment of the present invention. As shown in FIGS. 5A and 5B, a pair of first ribs 161 and second ribs 162 are provided on the left side surface 1541 and the right side surface 1542 of the side wall 154 of the air passage switching plate 150 opposite to the air passage wall 170. That is, the first rib 161 and the second rib 162 are radially disposed from the rotation shaft 151 like the end surface of the side plate 154 of the air passage switching plate 150.

Further, third ribs 171 are provided at the central positions of the left side and the right side 176 of the air passage wall 170, respectively. That is, the third bead 171 is disposed on a line connecting the rotating shaft 151 of the air passage switching plate 150 to the lower end of the air outlet 111. Moreover, the third rib 171 is located between the first rib 161 and the second rib 162.

When the heating ventilation fan is operated in the ventilation mode or the heating mode, the first rib 161 and the third rib 171, or the second, which are disposed on the air passage switching plate 150 and the air passage wall 170, by setting the position of the air passage switching plate 150 are set. The rib 162 and the third rib 171 overlap and overlap each other, and the air passage from the air outlet 132 to the air outlet 111 of the ventilating fan provided on the side wall of the frame 110 of the ventilating fan and the air outlet 132 are provided to the ventilating fan mask. The air path blown to the air outlet 112 in the room is separated to prevent the wind from directly switching from the air passage switch plate 150 (not shown) A gap with the air passage wall 170 flows to the outside of the air passage switching plate 150.

Specifically, as shown in FIG. 5C, a cross-sectional view of the heating ventilating fan 100 for the bathroom in the heating mode is controlled by the stepping motor, and the air passage switching plate 150 is turned to the top surface 134 side of the snail shell 131. At this time, the wind path The second ribs 162 provided on the left side surface (not shown) and the right side surface 1542 of the switching plate 150 are respectively engaged with the left ribs 171 provided on the left side (not shown) and the right side 176 of the air passage wall 170. In the closed state, the wind is prevented from flowing directly from the gap between the air passage switching plate 150 and the air passage wall 170 to the outside of the air passage switching plate 150.

As shown in FIG. 5D, a cross-sectional view of the heating ventilating fan 100 for the bathroom in the ventilation mode is controlled by the stepping motor, and the air passage switching plate 150 is turned to the bottom surface 135 side of the snail shell 131. At this time, the left side of the air passage switching plate 150 The first ribs 161 provided on the surface (not shown) and the right side surface 1542 are respectively engaged with the third ribs 171 provided on the left side and the right side 176 of the air passage wall 170 to form a close state, thereby preventing the wind. The flow directly flows from the gap between the air passage switching plate 150 and the air passage wall 170 to the outside of the air passage switching plate 150.

6A, 6B, 6C, and 6D are schematic views showing a fifth embodiment of the present invention. As shown in FIGS. 6A and 6B, first ribs 164 and second ribs 165 opposed to the air passage wall 170 are provided on the outer side of the front end portion 1521 and the rear end portion 1522 of the air passage switching plate 150, respectively, on the air passage wall. A third rib 186 is provided at a lower middle end of the side of the air outlet 111 of the 170. Moreover, the sixth rib 186 is located between the first rib 164 and the second rib 165.

When the heating ventilation fan is operated in the ventilation mode or the heating mode, the first ribs 164 and the third portions provided to the air passage switching plate 150 and the air passage wall 170 are passed. The rib 186 or the second rib 165 and the third rib 186 are overlapped and engaged, and wind can be prevented from flowing directly from the gap between the air passage switching plate 150 and the air passage wall 170 to the outside of the air passage switching plate 150.

Specifically, as shown in FIG. 6C, a cross-sectional view of the heating ventilating fan 100 for the bathroom in the heating mode is controlled by the stepping motor, and the air passage switching plate 150 is turned to the top surface 134 side of the snail shell 131. At this time, the wind path The second rib 165 of the rear end portion 1522 of the switching plate 150 is engaged with the third rib 186 of the air passage wall 170 to form a close state, thereby preventing wind from directly between the air passage switching plate 150 and the air passage wall 170. The gap flows to the outside of the air passage switching plate 150.

As shown in FIG. 6D, a cross-sectional view of the heating ventilating fan 100 for the bathroom in the ventilation mode is controlled by the stepping motor, and the air passage switching plate 150 is turned to the bottom surface 135 side of the snail shell 131. At this time, the air passage switching plate 150 The first rib 164 of the front end portion 1521 is engaged with the third rib 186 of the air passage wall 170 to form a close state, thereby preventing the wind from directly flowing from the gap between the air passage switching plate 150 and the air passage wall 170 to the wind. The outside of the road switching board 150.

Further, as shown in FIG. 6C, this embodiment also provides a "V"-shaped fourth rib 177 on the top surface 172 side of the air passage wall 170, and the lowest of the first rib 164 of the front end portion 1521 of the air passage switching plate 150. Point 1640 is higher than the lowest point 1770 of the fourth "V" shaped rib 177. The fourth rib 177 is provided with a front side 1772 on the side of the air outlet 132 and a rear side 1771 on the downstream side of the air outlet 132, and has an apex below it. Further, the cross-sectional shape thereof is a right-angled triangle formed by the front side 1772 as a hypotenuse and the rear side 177 as one side.

Moreover, when the heating ventilating fan 100 is operated in the heating mode, the step is passed. In the motor control, the air passage switching plate 150 is turned to the top surface 134 side of the snail shell 131. At this time, the first rib 164 of the front end portion 1521 of the air passage switching plate 150 is engaged with the rear side 1771 of the fourth rib 177. At the same time, the second rib 165 of the rear end portion 1522 of the air passage switching plate 150 is engaged with the third rib 186 of the air passage wall 170 to form a close state, and the fourth rib 177 of the "V" shape is formed. As described above, the front side 1772 has a beveled side having a triangular cross-sectional shape, that is, the front side 1772 has a function of guiding the wind blown by the air outlet side to the guide plate in the air passage switching plate 150. Therefore, the fourth rib 177 of the above-mentioned "V" shape can prevent the wind from directly flowing from the gap between the air passage switching plate 150 and the air passage wall 170 to the outside of the air passage switching plate 150, and can also reduce the wind resistance. Improve performance. Thereby improving product performance and energy utilization efficiency.

100‧‧‧Bathroom heating and ventilation fans

101,102‧‧

110‧‧‧Frame

111, 112, 132‧‧ vents

120‧‧‧ fan leaves

130‧‧‧Motor

131‧‧‧Snail shell

134,172‧‧‧ top

135‧‧‧ bottom

140‧‧‧heater

150‧‧‧Windway switchboard

151‧‧‧ shaft

152‧‧‧ motherboard

1521‧‧‧ front end

1522‧‧‧ Back end

154‧‧‧ side panels

1541‧‧‧left side

1542‧‧‧ right side

155‧‧‧Transfer

160‧‧‧ suction port

161‧‧‧First rib

162‧‧‧second rib

164‧‧‧First rib

1640, 1770‧‧‧ lowest point

165‧‧‧second rib

170‧‧‧ Wind Road Wall

171‧‧‧ Third rib

176‧‧‧right

177‧‧‧4th rib

1771‧‧‧ Back side

1772‧‧‧ front side

180,390‧‧‧ gap

186‧‧‧ third rib

190,290‧‧‧ interval

200,300,400‧‧‧1 piece

210‧‧‧Upper

220‧‧‧Bottom

Figure 1 is a schematic diagram of a prior art.

2A, 2B, and 2C are schematic views of the first embodiment.

3A and 3B are schematic views of a second embodiment.

4A and 4B are schematic views of a third embodiment.

5A, 5B, 5C, and 5D are schematic views of a fourth embodiment.

6A, 6B, 6C, and 6D are schematic views of a fifth embodiment.

100‧‧‧Bathroom heating and ventilation fans

110‧‧‧Frame

111, 112, 132‧‧ vents

120‧‧‧ fan leaves

130‧‧‧Motor

131‧‧‧Snail shell

134‧‧‧ top surface

140‧‧‧heater

150‧‧‧Windway switchboard

152‧‧‧ motherboard

1521‧‧‧ front end

154‧‧‧ side panels

155‧‧‧Transfer

160‧‧‧ suction port

170‧‧‧ Wind Road Wall

190‧‧‧ interval

200‧‧‧1 piece

210‧‧‧Upper

220‧‧‧Bottom

Claims (10)

A heating ventilating fan for a bathroom, comprising: a ventilating fan frame, a snail shell provided with a fan blade and a motor, a wind circuit switching plate disposed at a downstream of the snail shell air outlet and capable of switching at least two directions of the air path, and a heater, wherein The air leakage preventing structure for guiding the air into the air passage switching plate is provided at the air outlet of the snail shell, and the air leakage preventing structure is a protruding piece protruding from the air outlet of the snail shell to the air passage switching plate, and the air passage switching board has a fin that overlaps the outer side of the tab, and an air passage wall forming the air passage is extended from the air outlet of the snail shell, and the tab is formed between the downstream side of the air outlet of the snail shell and the air passage wall of the air passage. The interval in which the air passage switching plate rotor is accommodated. The heating ventilating fan for a bathroom according to claim 1, wherein the tab is disposed around the entire air outlet of the snail shell. The heating ventilating fan for a bathroom according to claim 1, wherein the lobes protrude from a position of the air passage switching plate that is located above the rotating shaft of the snail shell air outlet. The heating ventilating fan for a bathroom according to claim 1, wherein the lobes are protruded from a position lower than a rotating shaft of the snail shell air outlet. The heating ventilating fan for a bathroom according to claim 1 is further provided with another air leakage preventing structure for guiding the air into the air passage switching plate at the air outlet of the snail shell, and the other air leakage preventing structure refers to the air path. The switching plate and the air passage wall are provided with a plurality of ribs that can be engaged with each other. The heating ventilating fan for a bathroom according to claim 5, wherein the ribs are respectively disposed on the left and right sides of the air passage switching plate and the air passage wall On the side, the ribs on the air passage switching plate and the ribs on the air passage wall can be engaged with each other. The heating ventilating fan for a bathroom according to claim 5, wherein the first rib and the second rib are respectively disposed on the sides of the left and right sides adjacent to the air passage switching plate and the air passage wall, in the wind A third rib is disposed at a middle portion of the left and right sides of the road wall. The heating ventilating fan for a bathroom according to claim 5, wherein the first rib and the second rib are respectively disposed on the front end and the rear end of the air passage switching plate adjacent to the air passage wall, in the air path A third rib is disposed at a central portion of the wall outlet side. The heating ventilating fan for a bathroom according to claim 8, wherein a fourth V-shaped fourth rib is disposed on a top surface side of the air passage wall, and the first rib of the front end of the air switching plate is lowest The point is higher than the lowest point of the fourth rib of the "V" shape. A heating ventilating fan for a bathroom, comprising: a ventilating fan frame, a snail shell provided with a fan blade and a motor, a wind circuit switching plate disposed at a downstream of the snail shell air outlet and capable of switching at least two directions of the air path, and a heater, wherein The air leakage preventing structure for guiding the air into the air passage switching plate is provided at the air outlet of the snail shell, and the air leakage preventing structure is provided with a plurality of convex ribs that can be engaged with each other on the air passage switching plate and the air passage wall. a first rib and a second rib are respectively disposed on the front end and the rear end of the road switching plate adjacent to the air passage wall, and a third rib is disposed at a middle position on the air outlet side of the air passage wall, and the wind is still in the wind a fourth rib of a "V" shape is disposed on a top side of the road wall, and a lowest point of the fourth rib at the front end of the air passage switching plate is higher than a lowest point of the first rib of the "V" shape point.