Air Regulating Device for Indoor and Outdoor Air Circulation

Abstract

An air regulating device includes a casing assembly, an outdoor fresh air regulator, a fan assembly, and a heating assembly. The casing assembly includes a front casing having a first fresh air inlet and an air outlet, and a rear casing has a second fresh air inlet. The outdoor fresh air regulator includes a front damper gate coupled at the front casing to selectively open and close the first fresh air inlet, and a rear damper gate coupled at the rear casing to selectively open and close the second fresh air inlet. The fan assembly is arranged to suck outdoor fresh air from the second fresh air inlet to the air outlet. The heating assembly is disposed within the air tunnel for heating up the outdoor fresh air before entering into the indoor side at the air outlet.

Claims

1. An air regulating device for indoor and outdoor air circulation, comprising: a casing assembly 10 comprising a front casing 11 and a rear casing 12 securely coupled to the front casing 11, wherein the front casing 11 has an air outlet 11 and a first fresh air inlet 112, wherein the rear casing 12 has a second/third fresh air inlet 121A, 121B; an outdoor fresh air regulator 20 comprising a front damper gate 21 coupled at the front casing and a rear damper gate 22 coupled at the rear casing, wherein the front and rear damper gates 21, 22 are movable at the front and rear casings to fully open, fully close, and partially open-partially close the first fresh air inlet of the front casing and the second/third fresh air inlet of the rear casing respectively for introducing an outdoor fresh air into a room and for providing an indoor and outdoor air circulation; a fan assembly 30 comprising a first/second fan wheel 31A/31B, a first/second fan wheel housing 32A, 32B, a first/second air tunnel 33A, 33B, and a first/second motor 34A, 34B, wherein the first/second fan wheel 31A, 31B is laterally supported in the first/second fan wheel housing 32A, 32B, wherein the first/second air tunnel 33A, 33B is coupled at a lower portion of the first/second fan wheel housing 32A, 32B, wherein the first/second motor 34A, 34B is electrically connected to a shaft of the first/second fan wheel; and a heating assembly 40 supported at an air tunnel outlet of the first/second air tunnel 33A, 33B and electrically connected to a control switch.

2. The air regulating device, as recited in claim 1, wherein the front and rear casings 11, 12 of the casing assembly are coupled with each other by connecting four corners of the front casing to four corners of the rear casing via screws, wherein the first fresh air inlet 112 and the air outlet 111 are provided at upper and lower portions of front casing respectively, wherein the air outlet is located corresponding to the heating assembly, wherein each of first fresh air inlet 112 and the air outlet 111 has a plurality of air through apertures being lined up regularly or irregularly, wherein the second/third fresh air inlet 121A, 121B is provided at an upper portion of the rear casing and has a plurality of air through apertures being lined up regularly or irregularly.

3. The air regulating device, as recited in claim 1, wherein the front damper gate 21 comprises a first gate plate 211, two front gate sliders 212 each having a front gate sliding groove, and a front damper gate positioning assembly 213, wherein the first gate plate 211 has a size larger than the first fresh air inlet 112, wherein the two front gate sliders 212 are provided at two sides of the first fresh air inlet 112 of the front casing, wherein two sides of the first gate plate 211 are slidably coupled at the front gate sliders 211 respectively to allow the first gate plate 211 being moved up and down, wherein the front damper gate positioning assembly 213 is arranged to retain the first gate plate 211 after the first gate plate 211 is moved in a desired position.

4. The air regulating device, as recited in claim 3, wherein the front damper gate positioning assembly 213 comprises a plurality of elastic positioning protrusions 2131 spacedly provided at the two sides of the first gate plate 211 and a plurality of positioning recesses 2132 spacedly indented on inner walls of the front gate sliding grooves of the two front gate sliders 212 corresponding to the elastic positioning protrusions 2131, wherein when the first gate plate 211 is moved up and down in the desired position, the elastic positioning protrusions 2131 are engaged with the positioning recesses 2132 so as to retain the first gate plate 211 in the desired position.

5. The air regulating device, as recited in claim 4, wherein each of the elastic positioning protrusions 2131 comprises a ball-shaped retention pin 21311, a spring 21312, and a spring slot 21313 formed at the side of the first gate plate to receive the spring 21312, wherein the spring 21312 has one end biasing against the retention pin 21311 and an opposed end affixing to a bottom of the spring slot 21313, such that a portion of the retention pin 21311 is pushed, via the spring 21312, out of the spring slot 21313.

6. The air regulating device, as recited in claim 1, wherein the rear damper gate 22 comprises a second gate plate 221 and two rear gate sliders 222, wherein the rear gate plate 221 has a size larger than the second/third fresh air inlet 121A, 121B, wherein the two rear gate sliders 222 are provided at upper and lower sides of the second/third fresh air inlet 121A, 121B of the rear casing, wherein two sides of the second gate plate 211 are slidably coupled at the rear gate sliders 222 respectively, such that the second gate plate 211 is actuated to move left and right along the rear gate sliders 222.

7. The air regulating device, as recited in claim 1, wherein the first/second fan wheel housing 32A, 32B is configured to have an arc-shaped body, wherein two first end covers 321A are coupled at two sides of the first fan wheel housing 32A respectively, wherein the first motor 34A is installed into a first motor base 341A, wherein the first motor base 341A is securely coupled at an exterior side of one of the first end covers 321A, wherein each of the first end covers 321A has a first bearing slot 322A, wherein a first motor bearing 323A is installed into the first bearing slot 322A of the first end cover 321A, wherein four first screw hole seats 326A are formed at four corners of an opening rim of the first fan wheel housing 32A, wherein an opening of the second fan wheel housing 32B is configured to face toward the rear casing 12, wherein two second screw hole seats 323B are provided at upper and lower portions of the second fan wheel housing 32B at an exterior side thereof, wherein the second motor 34B is coupled within the second fan wheel housing 32B and the second fan wheel 31B, wherein two ends of the second motor 34B are coupled at the second fan wheel housing 32B and the second fan wheel 31B respectively, wherein one end of the second motor 32B is a motor shaft coupled to the second fan wheel 31B, wherein upper and lower ends of the first/second wheel housing 32A, 32B are configured as a first/second fan air inlet 324A, 321B and a first/second fan air outlet 325A, 322B respectively, wherein the first/second wheel housing 32A, 32B is coupled to the rear casing 12 through the first/second screw hole seats 326A, 323B via screws.

8. The air regulating device, as recited in claim 1, wherein the first/second air tunnel 33A, 33B is constructed to have an arc-shaped or a U-shaped first/second front air tunnel 331A, 331B, and an arc-shaped first rear air tunnel 332A or a second rear air tunnel 332B, wherein the first/second front air tunnel 331A, 331B is coupled to the first/second rear air tunnel 332A, 332B to form an arc-shaped first/second air passage 333A, 333B, wherein an upper opening of the first/second air tunnel 33A, 33B is configured as a first/second duct air inlet 33A1, 33B1 coupled to the first/second fan air outlet 325A, 322B of the first/second fan wheel housing, wherein a lower opening of the first/second air tunnel 33A, 33B is configured as a first/second duct air outlet 33A2, 33B2 corresponding to and extending toward the air outlet 111 of the front casing 11.

9. The air regulating device, as recited in claim 1, wherein the heating assembly 40 comprises a PTC heating element and four L-shaped supporting frames 41 coupled at four corners of the PTC heating element to couple the PTC heating element within the first duct air outlet 33A2, 33B2 at the lower portion of the first air tunnel, wherein an electrode terminal of the PTC heating element is electrically connected to an external power supply and the control switch.

10. An air regulating device for communicating an indoor side with an outdoor side, comprising: a casing assembly comprising a front casing having has a first fresh air inlet and an air outlet for communicating with the indoor side, and a rear casing has a second fresh air inlet for communicating with the outdoor side, wherein the front and rear casings are securely coupled with each other; an outdoor fresh air regulator comprising a front damper gate movably coupled at the front casing to selectively open, close, or partially open-partially close the first fresh air inlet, and a rear damper gate movably coupled at the rear casing to selectively open, close or partially open-partially close the second fresh air inlet; a fan assembly comprising a motor, a fan wheel driven to operate by the motor, a fan wheel housing receiving the fan wheel therein and communicating with the first and second fresh air inlet, and an air tunnel extended from the fan wheel housing to the air outlet, wherein when the rear damper gate is operated to open up the second fresh air inlet, the fan wheel driven to operate by the motor for sucking an outdoor fresh air from the outdoor side to the indoor side at the air outlet through the air tunnel, wherein when the rear damper gate is operated to close the second fresh air inlet and when the front damper gate is operated to open up the first fresh air inlet, the fan wheel driven to operate by the motor for circulating an indoor air at the indoor side; and a heating assembly within the air tunnel for heating up the outdoor fresh air or indoor air before entering into the indoor side at the air outlet.

11. The air regulating, as recited in claim 10, wherein the front damper gate comprises a first gate plate having a size larger than the first fresh air inlet and two front gate sliders, each having a front gate sliding groove, provided at two sides of the first fresh air inlet of the front casing respectively, wherein two sides of the first gate plate are slidably coupled at the front gate sliding groove of the front gate sliders respectively to allow the first gate plate being moved up and down in a desired position for selectively open and close the first fresh air inlet.

12. The air regulating, as recited in claim 11, wherein the front damper gate further comprise a front damper gate positioning assembly is arranged to retain the first gate plate in the desired position, wherein the front damper gate positioning assembly comprises a plurality of elastic positioning protrusions spacedly provided at the two sides of the first gate plate and a plurality of positioning recesses spacedly indented on inner walls of the front gate sliding grooves of the two front gate sliders corresponding to the elastic positioning protrusions, wherein when the first gate plate is moved up and down in the desired position, the elastic positioning protrusions are engaged with the positioning recesses to retain the first gate plate in the desired position.

13. The air regulating device, as recited in claim 12, wherein each of the elastic positioning protrusions comprises a ball-shaped retention pin, a spring, and a spring slot formed at the side of the first gate plate to receive the spring, wherein the spring has one end biasing against the retention pin and an opposed end affixing to a bottom of the spring slot, such that a portion of the retention pin is pushed, via the spring, out of the spring slot.

14. The air regulating device, as recited in claim 12, wherein the rear damper gate comprises a second gate plate having a size larger than the second fresh air inlet, and two rear gate sliders provided at upper and lower sides of the second fresh air inlet of the rear casing respectively, wherein two sides of the second gate plate are slidably coupled at the rear gate sliders respectively, such that the second gate plate is actuated to move left and right along the rear gate sliders.

15. The air regulating device, as recited in claim 14, wherein the motor is coupled at an exterior side of the fan wheel housing to couple with the fan wheel within the fan wheel housing so as to drive the fan wheel to rotate within the fan wheel housing.

16. The air regulating device, as recited in claim 14, wherein the motor is coupled within the fan wheel housing and the fan wheel, wherein the motor has one end coupled at the fan wheel housing and an opposed motor end coupled to the fan wheel so as to drive the fan wheel to rotate within the fan wheel housing.

17. The air regulating device, as recited in claim 15, wherein the air tunnel is constructed to have an arc-shaped front air tunnel and a rear air tunnel coupled thereto to form an arc-shaped air passage, wherein the air tunnel has an upper opening serving as a duct air inlet coupled to the fan wheel housing and a lower opening serving as a duct air outlet extending toward the air outlet of the front casing.

18. The air regulating device, as recited in claim 16, wherein the air tunnel is constructed to have an arc-shaped front air tunnel and a rear air tunnel coupled thereto to form an arc-shaped air passage, wherein the air tunnel has an upper opening serving as a duct air inlet coupled to the fan wheel housing and a lower opening serving as a duct air outlet extending toward the air outlet of the front casing.

19. The air regulating device, as recited in claim 17, wherein the heating assembly comprises a PTC heating element coupled within the duct air outlet of the air tunnel.

20. The air regulating device, as recited in claim 18, wherein the heating assembly comprises a PTC heating element coupled within the duct air outlet of the air tunnel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1A is a front exploded perspective view of an air regulating device according to a first embodiment of the present invention, illustrating a front casing being detected from a rear casing.

[0020] FIG. 1B is an enlarged view of the rear casing of the air regulating device according to the above first embodiment of the present invention.

[0021] FIG. 2 is a rear exploded perspective view of the air regulating device according to the first embodiment of the present invention, illustrating the front casing being detected from the rear casing.

[0022] FIG. 3 is a front exploded perspective view of a fan assembly of the air regulating device according to the first embodiment of the present invention.

[0023] FIG. 4 is a rear exploded perspective view of the fan assembly of the air regulating device according to the first embodiment of the present invention.

[0024] FIG. 5 is a sectional view of the air regulating device according to the first embodiment of the present invention.

[0025] FIG. 6 is a sectional view of a front positioning assembly of the air regulating device according to the first embodiment of the present invention.

[0026] FIG. 7 is a front exploded perspective view of an air regulating device according to a second embodiment of the present invention, illustrating a front casing being detected from a rear casing.

[0027] FIG. 8 is a rear exploded perspective view of the air regulating device according to the second embodiment of the present invention, illustrating the front casing being detected from the rear casing.

[0028] FIG. 9 is a front exploded perspective view of a fan assembly of the air regulating device according to the second embodiment of the present invention.

[0029] FIG. 10 is a rear exploded perspective view of the fan assembly of the air regulating device according to the second embodiment of the present invention.

[0030] FIG. 11 is a sectional view of the air regulating device according to the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031] The following examples or embodiments are further explanations and illustrations of the present invention, and should not constitute any limitation to the present invention.

[0032] Referring to FIGS. 3 and 8 of the drawings, an air regulating device is illustrated for indoor and outdoor air circulation, wherein the air regulating device of the present invention comprises a casing assembly 10, an outdoor fresh air regulator 20, a fan assembly 30, and a heating assembly 40. The air regulating device can be used as a fan and a heater. When the air regulating device is used as a heater, it can not only introduce outdoor fresh air into a room for indoor and outdoor air circulation, but also heat up the outdoor fresh air into the room. The present invention will become apparent from the following detailed description and the accompanying drawings.

Embodiment 1

[0033] As shown in FIGS. 1A to 5, according to the air regulating device, the casing assembly 10 comprises a front casing 11 and a rear casing 12 securely coupled to the front casing 11. In one example, the front casing 11 has four front screw posts provided at four corners respectively and the rear casing 12 has four rear screw posts provided at four corners respectively. When the front casing 11 and the rear casing 12 are coupled with each other to align the front and rear screw posts with each other, the front casing 11 and the rear casing 12 can be secured by fixing screws to the front and rear screw posts respectively. The front casing 11 has a first fresh air inlet 112 provided at an upper portion thereof for indoor and outdoor air circulation, an air outlet 111 which is provided at a lower portion of the front casing 11 below the first fresh air inlet 112 and is positioned aligned with the heating assembly 40 for heating up the air into the room. The first fresh air inlet 112 and the air outlet 111 have a plurality of air through apertures, wherein the air through apertures can be arranged regularly or irregularly. In the first embodiment, the air through apertures are spacedly lined up in a row and column manner to form the first fresh air inlet 112 having a rectangular shape. The rear casing 12 has a second fresh air inlet 121A provided at an upper portion thereof for introducing the outdoor fresh air into the room in order to circulate air indoor and outdoor. The second fresh air inlet 121A also has a plurality of air through apertures spacedly lined up in a row and column manner to form the second fresh air inlet 121A having a rectangular shape.

[0034] As shown in FIGS. 1A, 1B and 2, the outdoor fresh air regulator 20 comprises a front damper gate 21 and a rear damper gate 22. The front damper gate 21 is movably arranged on an outer upper portion of the front casing 11 at a position corresponding to the first fresh air inlet 112 of the front casing 11 for opening, closing or partially opening-partially close the first fresh air inlet 112. As shown in FIGS. 3 and 4, the front damper gate 21 comprises a first gate plate 211, two front gate sliders 212, and a front damper gate positioning assembly 213. The first gate plate 211, having a rectangular shaped, is shaped and sized larger than the first fresh air inlet 112. Therefore, when the first gate plate 211 is moved in a closed position, the first fresh air inlet 112 is entirely covered by the first gate plate 211 to block the air passing through the first fresh air inlet 112. The two front gate sliders 212 are vertically provided at two sides of the first fresh air inlet 112 of the front casing 11, wherein two sides, i.e. the left and right sides, of the first gate plate 211 are slidably coupled at the front gate sliders 212 respectively. Accordingly, each of the front gate sliders 212 has a L-shaped cross section, and is protruded from the front casing 11 to form a front gate sliding groove therebetween, wherein openings of the front gate sliding grooves of the two front gate sliders 212 face toward each other. The two sides of the first gate plate 211 are slidably coupled at the front gate sliding grooves of the two front gate sliders 212 respectively, wherein the first gate plate 211 is actuated to move up and down along the front gate sliders 212 to regulate an amount of air passing through the first fresh air inlet 112. The front damper gate positioning assembly 213 is arranged to retain the first gate plate 211 after the first gate plate 211 is moved in a desired position. The front damper gate positioning assembly 213 comprises a plurality of elastic positioning protrusions 2131 and a plurality of positioning recesses 2132, wherein the elastic positioning protrusions 2131 are spacedly provided at the two sides of the first gate plate 211. The positioning recesses 2132 are spacedly indented on inner walls of the front gate sliding grooves of the two front gate sliders 212 corresponding to the elastic positioning protrusions 2131. Each of the elastic positioning protrusions 2131 comprises a ball-shaped retention pin 21311, a spring 21312, and a spring slot 21313 formed at the side of first gate plate 211 to receive the spring 21312, wherein the spring 21312 has one end biasing against the retention pin 21311 and an opposed end biasing against, preferably affixing to, a bottom of the spring slot 21313. A portion of the retention pin 21311 is pushed, via the spring 21312, out of the spring slot 21313. Each of the positioning recesses 2132 is a semicircular pit shaped corresponding to the retention pin 21311, wherein a diameter of each of the positioning recesses 2132 is slightly larger than a diameter of the retention pin 21311. When the first gate plate 211 is moved up and down in a desired position, the retention pins 21311 are pushed by the springs 21312 to engage with the positioning recesses 2132 respectively, such that the first gate plate 211 is held and retained in the desired position for maintaining the amount of air passing through the first fresh air inlet 112. The rear damper gate 22 is movably arranged on an outer upper portion of the rear casing 12 at a position corresponding to the second fresh air inlet 121A of the rear casing 12 for opening, closing or partially opening-partially close the second fresh air inlet 121A. The rear damper gate 22 comprises a second gate plate 221 and two rear gate sliders 222. The second gate plate 221 is shaped and sized larger than the second fresh air inlet 121A. Therefore, when the second gate plate 221 is moved in a closed position, the second fresh air inlet 121A is entirely covered by the second gate plate 221 to block the air passing through the second fresh air inlet 121A. The two rear gate sliders 222 are horizontally provided at upper and lower sides of the second fresh air inlet 121A of the rear casing 12, wherein two sides, i.e. the top and bottom sides, of the second gate plate 221 are slidably coupled at the rear gate sliders 222 respectively, such that the second gate plate 221 is actuated to move left and right along the rear gate sliders 222 to regulate an amount of air passing through the second fresh air inlet 121A.

[0035] As shown in FIGS. 1A, 1B and 2, when the air regulating device is installed on the window, the outdoor fresh air regulator 20 is operated to regulate the outdoor fresh air being intake into the room. When the front damper gate 21 is actuated in a closed position and the rear damper gate 22 is actuated in an opened position, the outdoor fresh air can be heated up and is introduced into the room through the second fresh air inlet 121A, so as to achieve the indoor and outdoor air circulation. When the front damper gate 21 is partially or fully opened and the rear damper gate 22 is closed, the indoor air can be circulated and heated, so as to enhance the space heating effect of the room.

[0036] As shown in FIGS. 1A to 5, the fan assembly 30 is supported in the casing assembly 10 for introducing the outdoor fresh air into the room. The fan assembly 30 comprises a fan wheel 31A, a first fan wheel housing 32A, a first air tunnel 33A, and a first motor 34A. The first fan wheel 31A is configured as a horizontal drum type centrifugal wind wheel, and is arranged laterally in the first fan wheel housing 32A. The first fan wheel housing 32A is configured to have an arc-shaped body, wherein two first end covers 321A are coupled at two sides of the first fan wheel housing 32A respectively. Each of the first end covers 321A has a first bearing slot 322A, wherein a first motor bearing 323A is installed into the first bearing slot 322A of the first end cover 321A. The first motor 34A is installed into the first motor base 341A, wherein the first motor base 341A is securely coupled at an exterior side of one of the first end covers 321A. A motor shaft of the first motor 34A is connected to a fan wheel shaft of the first fan wheel 31A. As shown in FIG. 5, upper and lower ends of the first wheel housing 32A are configured as a first fan air inlet 324A and a first fan air outlet 325A respectively. An opening of the first fan wheel housing 32A faces toward the rear casing 12 to communicate with the first and second fresh air inlets, wherein four first screw hole seats 326A are formed at four corners of a rim of the opening of the first fan wheel housing 32A, such that the rim of the opening of the first fan wheel housing 32A is coupled to the rear casing 12 by coupling the first screw hole seats 326A to the rear casing 12 via screws. The first air tunnel 33A is coupled at a lower portion of the first fan wheel housing 32A to guide the outdoor fresh air from the first fan wheel 321A to the heating assembly 40 so as to heat up the outdoor fresh air thereby. The first air tunnel 33A is constructed to have an arc-shaped first front air tunnel 331A and a first rear air tunnel 332A, wherein an upper opening of the first front air tunnel 331A is coupled to a lower opening of the first rear air tunnel 332A to form an arc-shaped first air passage 333A through the first front air tunnel 331A and the first rear air tunnel 332A. An upper opening of the first air tunnel 33A is configured as a first duct air inlet 33A1 coupled to the first fan air outlet 325A of the first wheel housing 32A. A lower opening of the first air tunnel 33A is configured as a first duct air outlet 33A2 corresponding to and extending toward the air outlet 111 of the front casing 11. In other words, the first duct air inlet 33A1 and the first duct air outlet 33A2 are configured as upper and lower openings first air passage 333A respectively. The outdoor fresh air sent by the first fan wheel 31A is arranged to enter into the first air tunnel 33A to the first air passage 333A through the first duct air inlet 33A1, and then the outdoor fresh air is guided to the lower opening of the first duct air outlet 33A2 for being heated by the heating assembly 40.

[0037] As shown in FIGS. 1A to 5, the heating assembly 40 is supported within the first air tunnel 33A for heating up the outdoor fresh air sent by the first fan wheel 31A through the first air tunnel 33A so as to generate a warm fresh air flow into the room. According to the first embodiment, the heating assembly 40 comprises a PTC (Positive Temperature Coefficient) heating element 401, which is an applicable commercially available product, supported within the air tunnel outlet of the first air tunnel 33A. The heating assembly 40 comprises four L-shaped supporting frames 41 coupled at four corners of the PTC heating element 401, wherein each of the supporting frames 41 has a gap formed at a center portion of a straight side for an electrode terminal of the PTC heating element 401 passing through. The PTC heating element 401 is coupled within the first duct air outlet 33A2 at the lower portion of the first air tunnel 33A via the supporting frames 41, wherein the electrode terminal of the PTC heating element 401 is electrically connected to an external power supply and a control switch for controlling an operation of the PTC heating element 401, such as on and off control, and temperature control. The PTC heating element 401 is constructed by one or more PTC heating sheets connecting with the electrode sheets and aluminum heat sinks in parallel, wherein the aluminum heat sinks are configured in a corrugated manner and disposed at an exterior of the PTC heating sheeting to dissipate the heat generated by the PTC heating sheet to outside.

Embodiment 2

[0038] According to the second embodiment, the structural configuration of the second embodiment is similar to that of the first embodiment, such that the second embodiment is considered as a modification or alternative of the first embodiment. The differences therebetween are that the rear casing 12 comprises a third fresh air inlet 121B provided thereat, wherein the third fresh inlet 121B has a plurality of fan-shaped air through apertures spacedly and radially lined up to form the third fresh air inlet 121B having a circular shape. In other words, the fan-shaped air through apertures are lined up in a circumferential direction of the third air inlet 121B. The rear casing 12 further comprises a second end cover 121B1, having a wheel shape, coupled at an exterior side of the third air inlet 121B. Correspondingly, the second fan wheel 31B of the fan assembly 30 is a disc type centrifugal wind wheel, and is disposed in the second fan wheel housing 32B having a disc shape. An opening of the second fan wheel housing 32B is configured to face toward and align with the third fresh air inlet 121B at the rear casing 12. The second motor 34B is installed at a center of the second fan wheel 31B.

[0039] The second air tunnel 33B is coupled at a lower portion of the second fan wheel housing 32B. The second air tunnel 33B is constructed to have a U-shaped second front air tunnel 331B and an arc-shaped second rear air tunnel 332B, wherein the second front air tunnel 331B is coupled to the second rear air tunnel 332B to form an arc-shaped second air passage 333B. An upper opening of the second air tunnel 33B is configured as a second duct air inlet 33B1 coupled to the second fan air outlet 322B of the second fan wheel housing 32B. A lower opening of the second air tunnel 33B is configured as a second duct air outlet 33B2 corresponding to and extending toward the air outlet 111 of the front casing 11.

[0040] Two second screw hole seats 323B are provided at upper and lower portions of the second fan wheel housing 32B at an exterior side thereof, wherein the second motor 34B is coupled within the second fan wheel housing 32B and the second fan wheel 31B. Two ends of the second motor 34B are coupled at the second fan wheel housing 32B and the second fan wheel 31B respectively, wherein one end of the second motor 32B is a motor shaft coupled to the second fan wheel 31B. Upper and lower ends of the first/second wheel housing 32A, 32B are configured as a first/second fan air inlet 324A, 321B and a first/second fan air outlet 325A, 322B respectively, wherein the first/second wheel housing 32A, 32B is coupled to the rear casing 12 through the first/second screw hole seats 326A, 323B via screws.

[0041] Although the present invention has been fully and effectively accomplished, the embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.