CN111412497A - Range hood and control method for introducing fresh air into range hood - Google Patents

Abstract

The invention discloses a range hood, which comprises a fume collecting hood and a first box body arranged above the fume collecting hood, wherein a first fan is arranged in the first box body, the fume collecting hood comprises an outer cover and inner covers arranged in the outer cover at intervals, the whole inner cover is in an upwards sunken shape to form a fume collecting cavity, and an oil fume channel communicated with the inside of the first box body is formed in the fume collecting cavity, and the range hood is characterized in that: still include the new trend device, the new trend device is including being used for introducing the second fan in the collection petticoat pipe with outside fresh air and setting up the wind channel baffle between dustcoat and inner cover, the wind channel baffle separates the new trend passageway of keeping apart with the oil smoke passageway with the space between dustcoat and the inner cover, collection petticoat pipe front side is formed with the first new trend export with new trend passageway intercommunication, collection petticoat pipe bottom periphery is formed with the second new trend export with new trend passageway intercommunication. Also discloses a control method for introducing fresh air into the range hood.

Description

Range hood and control method for introducing fresh air into range hood

Technical Field

The invention relates to oil fume purification equipment, in particular to a range hood and a control method for introducing fresh air of the range hood.

Background

When a kitchen is cooked, the generated oil fume not only pollutes the indoor environment, but also influences the health of people. In order to remove the oil smoke, a range hood is usually adopted to absorb and discharge the oil smoke. However, in actual operation, due to factors such as the limit of the suction force of the range hood, a part of the oil smoke escapes, and in order to avoid the influence of the airflow on the oil smoke and the flame of the cooker, the kitchen environment is relatively closed during operation, which affects the use experience of a user.

At present, an air curtain technology or a smoke guide plate technology is usually adopted for oil smoke escape. Wherein the air curtain technique is mainly through introducing outside air, gathers together the oil smoke in the air curtain, like the lampblack absorber that chinese patent publication of application number 201811023953.4 discloses, including the air curtain system, the air curtain system includes the wind channel, is provided with the fan in the wind channel, and the fan makes the air current flow in from the air intake in wind channel, flows and forms the air curtain from the air outlet in wind channel again, and the air curtain is used for preventing smog to the outside diffusion. The smoke guide plate technology is mainly used for increasing the space of the smoke collecting cover and increasing the effect of the cigarette cage. The lifting range hood disclosed by the Chinese patent with the application number of 201820467703.9 comprises a range hood body and a smoke guide plate, wherein the range hood body comprises a fan and a control module, the range hood further comprises a lifting mechanism, the lifting distance of the lifting mechanism is adjusted by the control module according to the working gear of the fan, the lifting mechanism comprises a lifting motor, a guide rail and a sliding assembly, one end of the sliding assembly is connected with the range hood body, and the other end of the sliding assembly is connected with the smoke guide plate.

However, the existing air curtain system mainly introduces external air or directly introduces gas in a smoke suction channel, the air quality cannot be guaranteed, and air outlets of the air curtain are mostly concentrated on the front side and the rear side of the range hood, so that oil smoke escaping in the left-right direction is difficult to completely collect; in the aspect of kitchen operation experience, ventilation equipment needs to be additionally installed for discharging indoor air, so that an operator cannot breathe fresh air, and the use experience of the operator is reduced; the external introduced air channel and the oil smoke suction channel are directly isolated by the partition board, so that complete isolation of oil smoke and air in the two channels is difficult to guarantee, and oil smoke gas can be discharged into a room again to a certain degree.

Disclosure of Invention

The first technical problem to be solved by the invention is to provide a range hood with a fresh air function, which aims to solve the problems in the prior art, improve the smoke collecting capability, provide fresh air for a user and improve the use experience.

The second technical problem to be solved by the invention is to provide a control method for introducing fresh air of the range hood.

The technical scheme adopted by the invention for solving the first technical problem is as follows: the utility model provides a range hood, includes collection petticoat pipe and sets up the first box in collection petticoat pipe top, be provided with first fan in the first box, the collection petticoat pipe includes the dustcoat and sets up the inner cover in the dustcoat with the interval ground, the whole shape that is upwards sunken of inner cover and forms the collection smoke chamber, the collection smoke intracavity constitutes the oil smoke passageway that communicates in with the first box, its characterized in that: still include the new trend device, the new trend device is including being used for introducing the second fan in the collection petticoat pipe with outside fresh air and setting up the wind channel baffle between dustcoat and inner cover, the wind channel baffle separates the new trend passageway of keeping apart with the oil smoke passageway with the space between dustcoat and the inner cover, collection petticoat pipe front side is formed with the first new trend export with new trend passageway intercommunication, collection petticoat pipe bottom periphery is formed with the second new trend export with new trend passageway intercommunication.

In order to form an independent fresh air channel conveniently, the air channel partition plate comprises an outer partition plate connected with the outer cover and an inner partition plate connected with the inner cover, the fresh air channel is formed between the outer partition plate and the inner partition plate, a first air inlet is formed in the top of the inner cover, and the outer partition plate and the inner partition plate are arranged around the first air inlet respectively.

In order to facilitate the communication between the oil fume channel and the fresh air channel and respective power sources, the outer cover comprises a top plate, side plates, a front plate and a rear plate, the side plates are located on the left side and the right side of the top plate and extend downwards, the front plate is located on the front side of the top plate and extends downwards, the rear plate is located on the rear side of the top plate and extends downwards, the outer cover is in a shape of a lower opening, a second air inlet is formed in the position, corresponding to the first air inlet, of the top plate, so that the oil fume channel is communicated with the second box body, a third air inlet is formed in the position, corresponding to the air outlet of the second fan, of the top plate, a fourth air inlet is formed in the position, located on the front side of.

In order to form a fresh air outlet, the first fresh air outlet is arranged on the front plate of the outer cover of the fume collecting hood, the part of the outer partition plate positioned on the front side of the first air inlet of the inner cover extends forwards to the upper end of the first fresh air outlet, the outer partition plates positioned on the left side and the right side are gradually inclined downwards from the position close to the first air inlet to the direction far away from the first air inlet and are connected with the bottom end of the side plate at the outer side end far away from the first air inlet, the outer partition plate positioned on the rear side is gradually inclined downwards from the position close to the first air inlet to the direction far away from the first air inlet and is connected with the bottom end of the rear plate at the outer side end far away from the first air inlet, the shape of the inner baffle is matched with that of the inner cover, the outer periphery of the inner baffle is connected with the outer periphery of the inner cover, thereby forming four second fresh air outlets, namely a front fresh air outlet, a rear fresh air outlet, a left fresh air outlet and a right fresh air outlet, between the outer periphery of the inner clapboard and the bottom of the outer cover.

In order to adjust the fresh air outlet conveniently and adapt to different cooking conditions and user requirements, a first guide plate is arranged at the first fresh air outlet, the first guide plate is rotatably connected with the front plate at the top, a second guide plate is arranged at the second fresh air outlet, and each second guide plate is rotatably connected with the bottom end of the outer cover of the fume collecting hood at the top.

In order to facilitate the arrangement of the second fan, the fresh air device further comprises a second box body, the second box body and the first box body are arranged above the smoke collecting hood in parallel, and the second fan is arranged in the second box body.

In order to drive the two fans and reduce energy consumption, the second box is arranged on the front side of the first box, the first fan is provided with a first fan air inlet facing the rear side of the first box, the second fan bag is provided with a second fan air inlet facing the front side of the second box, and the first fan and the second fan are coaxially arranged and share the same driving mechanism.

Preferably, the fresh air device is further including setting up the air-supply line in second box top, the air-supply line includes both ends open-ended, is used for introducing the first air inlet branch pipe of outdoor air and both ends open-ended, is used for introducing the second air inlet branch pipe of indoor air, and two air inlet branch pipes set up aslope, connect and are connected with the second box in the bottom.

Experience for improving user's use, first air inlet branch pipe periphery is provided with the first temperature sensor who is used for detecting outdoor air temperature, second air inlet branch pipe periphery is provided with the second temperature sensor who is used for detecting indoor air temperature, the air-supply line still includes according to two temperature sensor's signal, thereby make first air inlet branch pipe and second air inlet branch pipe only have one at the same time with the valve block of second box intercommunication, the valve block sets up the junction at first air inlet branch pipe and second air inlet branch pipe.

In order to remove impurities in the introduced air, the fresh air device further includes an air filter disposed upstream of the second fan in the air flow path.

The technical scheme adopted by the invention for solving the first technical problem is as follows: a control method for introducing fresh air of the range hood is characterized in that: the method comprises the following steps:

1) starting the range hood;

2) setting a desired temperature value X;

3) the first temperature sensor detects the current outdoor air temperature X1, the second temperature sensor detects the current indoor air temperature X2, the detected current temperature value is compared with the set temperature value, the difference value A between the outdoor air temperature and the set temperature value is | X1-X |, the difference value B between the indoor air temperature and the set temperature value is | X2-X |, and the sizes of A and B are judged:

3.1) if A is less than or equal to B, the valve plate closes the second air inlet branch pipe, the first air inlet branch pipe is communicated with the second box body, and fresh air is introduced from the outside;

3.2) if A is larger than B, the valve plate closes the first air inlet branch pipe, the second air inlet branch pipe is communicated with the second box body, and fresh air is introduced from the indoor space.

Compared with the prior art, the invention has the advantages that: fresh air is introduced from the outside or the inside to form a clean four-side surrounding type fan, oil smoke is effectively prevented from escaping, a fresh air outlet is formed at the front end, clean air can be directly provided for a user, and user experience is improved; the fresh air system is provided with a completely independent air duct system, does not generate air flow interaction with the oil smoke channel, and ensures the quality of air introduced into the room; the oil smoke is discharged and the fresh air device is integrated together, and no additional equipment is needed.

Drawings

FIG. 1 is a schematic view of a range hood according to an embodiment of the present invention;

FIG. 2 is a schematic view of a range hood according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view of a range hood in accordance with an embodiment of the present invention;

FIG. 4 is a cross-sectional view of a range hood in accordance with an embodiment of the present invention;

FIG. 5 is a schematic view of a smoke collection hood of a range hood according to an embodiment of the present invention;

FIG. 6 is a schematic view of a concealed top plate of a smoke collecting hood of the range hood according to the embodiment of the invention;

fig. 7 is a sectional view of a smoke collecting hood of a range hood according to an embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

Referring to fig. 1 to 7, a range hood includes a fume collecting hood 1, a first box 2 and a second box 3 disposed above the fume collecting hood 1, a first fan 4 disposed in the first box 2, an air outlet hood 5 for exhausting air from the first fan 4, a second fan 6 disposed in the second box 3, and an air inlet pipe 7 for allowing air from the second fan 6 to enter. For convenience of description, the terms "front", "rear", "left", "right", "up" and "down" refer to the orientation of the extractor hood relative to the user when in use, and do not limit the scope of the present invention.

The smoke collecting cover 1 includes an outer cover 11 and an inner cover 12 disposed in the outer cover 11, and the outer cover 11 includes a top plate 111, side plates 112 extending downward at left and right sides of the top plate 111, a front plate 113 extending downward at a front side of the top plate 111, and a rear plate 114 extending downward at a rear side of the top plate 111. From this, outer cover 11 forms the shape of under shed, inner cover 12 is arranged in outer cover 11 inside, and with outer cover 11 interval arrangement, inner cover 12 wholly is the shape of upwards caving, form the collection smoke chamber 121 of upwards caving from this, first air intake 122 has been seted up at the top of inner cover 12, second air intake 115 has been seted up to corresponding position on the roof 111 of outer cover 11, first box 2 is connected with the roof 111 of outer cover 11, the bottom opening of first box 2 is relative with second air intake 115, make collection smoke chamber 121 and the inside intercommunication of first box 2 from this, so that the oil smoke that cooks in-process production gets into in first box 2 through collection smoke chamber 121 from the range hood below. A smoke channel Q1 is formed in the smoke collection cavity 121.

A filter screen 8 is disposed at the first air inlet 122 or below the first air inlet 122 so as to filter the oil fume flow entering the first box 2.

The first fan 4 is a common centrifugal fan, the first fan 4 includes a first volute 41 and a first impeller 42 disposed in the first volute 41, a first fan air inlet 411 and a first fan air outlet 412 are formed on the first volute 41, the first fan air inlet 411 faces the rear side of the first box 2, and the first fan air outlet 412 faces the top of the first box 2, and is connected to an air outlet cover 5 located above the first box 2 so that oil smoke entering the first box 2 can be discharged to a common flue through the air outlet cover 5.

The second box 3, the second fan 6 and the air inlet pipe 7 form part of a fresh air device, wherein the second box 3 is arranged in parallel with the first box 2, and in the embodiment, the second box 3 is arranged at the front side of the first box 2. The top plate 111 of the outer cover 11 of the fume collecting hood 1 is further provided with a third air inlet 116, and the bottom of the second box 3 is opened and is opposite to the third air inlet 116. The second fan 6 is disposed in the second casing 3 and includes a second volute 61 and a second impeller 62 disposed in the second volute 6, a second fan inlet 611 and a second fan outlet 612 are formed on the second volute 61, the second fan inlet 611 faces the front side of the second casing 3, and the second fan outlet 612 faces the bottom of the second casing 3, so that the second fan 6 communicates with the inside of the smoke collecting hood 1.

The first fan 3 and the second fan 6 share the same driving mechanism, in this embodiment, a motor 20 with dual output shafts is adopted, the first impeller 32 of the first fan 3 and the second impeller 62 of the second fan 6 are coaxially arranged, and two output shafts of the motor 20 respectively penetrate through two boxes to be connected with corresponding impellers in the boxes, so that the first impeller 32 and the second impeller 62 can be synchronously driven to rotate. Sealing rings may be provided at the junction of the motor 20 and the two tanks to prevent gas leakage.

The first fan 3 and the second fan 6 are both centrifugal fans. Alternatively, the second fan 6 may also be a cross-flow fan, and similarly, the motor 20 is shared with the first fan 3 as a driving mechanism, and the air outlet is arranged in the same way as the centrifugal fan.

The air inlet pipe 7 is disposed above the second casing 3 and communicates with the inside of the second casing 3. The air inlet duct 7 includes a first air inlet branch duct 71 opened at both ends and a second air inlet branch duct 72 opened at both ends, which are obliquely disposed and connected at the bottom and to the second case 3. The first intake branch pipe 71 serves to introduce outdoor air, and the second intake branch pipe 72 serves to introduce indoor air. A valve plate 75 is disposed at the connection position of the first intake branch pipe 71 and the second intake branch pipe 72. A first temperature sensor 73 is provided around the first intake branch pipe 71, for example, adjacent to an end portion away from the second casing 3, for monitoring an outdoor temperature, and a second temperature sensor 74 is provided around the second intake branch pipe 72, for example, adjacent to an end portion away from the second casing 3, for monitoring an indoor temperature. The outdoor temperature and the indoor temperature are respectively compared with the temperature value set by the user through the difference value of the control program, the control valve plate 75 enables the air inlet branch pipe closest to the set temperature value to be communicated with the inside of the second box body 3, and the other air inlet branch pipe is closed.

When the range hood works, the control method for introducing fresh air comprises the following steps:

1) starting the range hood;

2) setting an expected temperature value X, wherein the temperature value X enables a user to be in a more comfortable environment temperature;

3) the first temperature sensor 73 detects the current outdoor air temperature X1, the second temperature sensor 74 detects the current indoor air temperature X2, compares the detected current temperature value with the set temperature value, the difference value a between the outdoor air temperature and the set temperature value is | X1-X |, the difference value B between the indoor air temperature and the set temperature value is | X2-X |, and judges the sizes of a and B:

3.1) if A is less than or equal to B, the valve plate 75 closes the second air inlet branch pipe 72, the first air inlet branch pipe 71 is communicated with the second box body 3, and fresh air is introduced from the outdoor;

3.2) if A is larger than B, the valve plate 75 closes the first air inlet branch pipe 71, the second air inlet branch pipe 72 is communicated with the second box body 3, and fresh air is introduced from the indoor.

The judgment of the temperature value and the control of the valve plate 75 can be realized through a control module of the range hood.

The new trend device is still including setting up in second box 3, being located the air cleaner 10 of 6 tops of second fan to filter the air that gets into from second box 3 outer, thereby provide pollution-free new trend, avoid containing the air injury user of impurity. In the flow path of the fresh air, the air filter 10 may be located upstream of the second fan 6.

The fresh air device also comprises an air duct partition plate arranged between the outer cover 11 and the inner cover 12 of the smoke collecting hood 1, and the air duct partition plate divides the space between the outer cover 11 and the inner cover 12 into a fresh air channel Q2. The air duct partition comprises an outer partition 91 connected with the outer cover 11 and an inner partition 92 connected with the inner cover 12, and the outer partition 91 and the inner partition 92 are respectively arranged around the first air inlet 122 of the inner cover 12 of the smoke collecting hood 1. The cavity between the outer partition 91 and the inner partition 92 constitutes the above-mentioned fresh air passage Q2. The part of the outer partition 91 located at the front side of the first air inlet 122 and the position corresponding to the third air inlet 116 of the top plate 111 are provided with a fourth air inlet 911 so as to communicate with the inside of the second box 3, so that the fresh air blown out by the second fan 6 can enter the fresh air channel Q2.

A first fresh air outlet 93 communicated with the fresh air channel Q2 is formed in a front plate 113 of the outer cover 11 of the smoke collecting cover 1, a part of the outer partition plate 91, which is located in front of the first air inlet 122 of the inner cover 12, extends forward to the upper end of the first fresh air outlet 93, and fresh air in the fresh air channel Q2 can be blown out from the first fresh air outlet 93 to the front side. The outer partition 91 located at the left and right sides is gradually inclined downward from being close to the first air inlet 122 to a direction away from the first air inlet 122, and is connected with the bottom end of the side plate 112 at an outer end portion away from the first air inlet 122, and the outer partition 91 located at the rear side is gradually inclined downward from being close to the first air inlet 122 to a direction away from the first air inlet 122, and is connected with the bottom end of the rear plate 114 at an outer end portion away from the first air inlet 122. The shape of the inner partition 91 is adapted to the shape of the inner cover 12 and is also in an upwardly concave shape, the outer periphery of the inner partition 91 is connected with the outer periphery of the inner cover 12, so that four second fresh air outlets 94 which are respectively formed between the outer periphery of the inner partition 91 and the bottom of the outer cover 11 (the bottom of the front plate 113, the bottoms of the two side plates 112 and the bottom of the rear plate 114) and are communicated with the fresh air channel Q2 are respectively formed, and fresh air in the fresh air channel Q2 can be blown out downwards from the second fresh air outlets 94. Alternatively, the first fresh air outlet 93 may be overlapped on the front plate 113 by other members.

The first fresh air outlet 93 is provided with a first guide plate 95, the first guide plate 95 is rotatably connected with the front plate 113 at the top, the second fresh air outlet 94 is provided with a second guide plate 96, and each second guide plate 96 is rotatably connected with the bottom end (the bottom ends of the side plate 112, the front plate 113 and the rear plate 114) of the outer cover 11 of the smoke collecting hood 1 at the top. The first guide plate 95 and the second guide plate 96 can be driven to rotate by a driving mechanism (such as the cooperation of an electric push rod and a hinge, or a motor and the like), and can also be rotated by manual operation, and only the rotating shaft of each guide plate needs to be in interference fit with the outer cover 11 during the manual operation. The air outlet angle of each fresh air outlet can be adjusted by adjusting the angle of each guide plate.

Through the arrangement of the air duct partition plate with the structure, the fresh air channel Q2 is independent and is isolated from the oil smoke channel Q1, so that the oil smoke is prevented from being discharged into the room again.

The fresh air blown out from the first fresh air outlet 93 can provide continuous fresh air for a user, and the fresh air blown out from the second fresh air outlets 94 forms an air curtain surrounded on four sides, so that the oil smoke can be effectively prevented from escaping, and the oil smoke absorption effect is improved. And the air outlet angle of each fresh air outlet can be adjusted according to the oil smoke escape condition and the fresh air demand of a user, so that the oil smoke absorption effect of the range hood and the overall experience of operation are improved.

In addition, the fresh air device can also be equipped with an air-conditioning fan function to provide cold/warm air.

Claims (11)

1. The utility model provides a range hood, includes collection petticoat pipe (1) and sets up first box (2) in collection petticoat pipe (1) top, be provided with first fan (4) in first box (2), collection petticoat pipe (1) includes outer cover (11) and sets up inner cover (12) in outer cover (11) with the interval, inner cover (12) wholly are the shape of upwards sunken and form collection smoke chamber (121), constitute in collection smoke chamber (121) with first box (2) in the oil smoke passageway (Q1) of intercommunication, its characterized in that: still include the new trend device, the new trend device is including being used for introducing second fan (6) in collection petticoat pipe (1) with outside fresh air and setting up the wind channel baffle between dustcoat (11) and inner cover (12), the space separation between with dustcoat (11) and inner cover (12) of wind channel baffle is separated fresh air channel (Q2) of keeping apart with oil smoke passageway (Q1), collection petticoat pipe (1) front side is formed with first fresh air export (93) with fresh air channel (Q2) intercommunication, collection petticoat pipe (1) bottom periphery is formed with second fresh air export (94) with fresh air channel (Q2) intercommunication.

2. The range hood of claim 1, wherein: the air duct partition plate comprises an outer partition plate (91) connected with the outer cover (11) and an inner partition plate (92) connected with the inner cover (12), a fresh air channel (Q2) is formed between the outer partition plate (91) and the inner partition plate (92), a first air inlet (122) is formed in the top of the inner cover (12), and the outer partition plate (91) and the inner partition plate (92) are respectively arranged around the first air inlet (122).

3. The range hood of claim 2, wherein: the outer cover (11) comprises a top plate (111), side plates (112) which are positioned at the left side and the right side of the top plate (111) and extend downwards, a front plate (113) which is positioned at the front side of the top plate (111) and extends downwards, and a rear plate (114) which is positioned at the rear side of the top plate (111) and extends downwards, so that the outer cover (11) forms a shape of a lower opening, a second air inlet (115) is arranged on the top plate (111) at a position corresponding to the first air inlet (122), therefore, the oil smoke channel (Q1) is communicated with the second box body (2), a third air inlet (116) is arranged on the top plate (111) at a position corresponding to the air outlet of the second fan (6), the part of the outer partition plate (91) positioned on the front side of the first air inlet (122) and the position corresponding to the third air inlet (116) are provided with a fourth air inlet (911), so that the second fan (6) is communicated with the fresh air channel (Q2).

4. The range hood of claim 3, wherein: the first fresh air outlet (93) is arranged on a front plate (113) of an outer cover (11) of the smoke collecting cover (1), the part of the outer partition plate (91) positioned at the front side of a first air inlet (122) of the inner cover (12) extends forwards to the upper end of the first fresh air outlet (93), the outer partition plates (91) positioned at the left side and the right side gradually incline downwards from the part close to the first air inlet (122) to the direction far away from the first air inlet (122) and are connected with the bottom end of the side plate (112) at the outer side end far away from the first air inlet (122), the outer partition plate (91) positioned at the rear side gradually inclines downwards from the part close to the first air inlet (122) to the direction far away from the first air inlet (122) and is connected with the bottom end of the rear plate (114) at the outer side end far away from the first air inlet (122), the shape of the inner partition plate (91) is matched with the shape of the inner cover (12), the outer periphery of the inner partition plate (91) is connected with the, thereby forming four second fresh air outlets (94) respectively in front, back, left and right between the outer periphery of the inner partition plate (91) and the bottom of the outer cover (11).

5. The range hood of claim 4, wherein: the first fresh air outlet (93) is provided with a first guide plate (95), the first guide plate (95) is rotatably connected with the front plate (113) at the top, the second fresh air outlet (94) is provided with a second guide plate (96), and each second guide plate (96) is rotatably connected with the bottom end of the outer cover (11) of the smoke collecting hood (1) at the top.

6. The range hood according to any one of claims 1 to 5, wherein: the fresh air device further comprises a second box body (3), the second box body (3) and the first box body (2) are arranged above the fume collecting hood (1) in parallel, and the second fan (6) is arranged in the second box body (3).

7. The range hood of claim 6, wherein: the second box body (3) is arranged on the front side of the first box body (2), the first fan (4) is provided with a first fan air inlet (411), the first fan air inlet (411) faces to the rear side of the first box body (2), the second fan (6) is provided with a second fan air inlet (611), the second fan air inlet (611) faces to the front side of the second box body (3), and the first fan (3) and the second fan (6) are coaxially arranged and share the same driving mechanism.

8. The range hood of claim 6, wherein: the fresh air device is characterized by further comprising an air inlet pipe (7) arranged above the second box body (3), wherein the air inlet pipe (7) comprises a first air inlet branch pipe (71) with two open ends and used for introducing outdoor air and a second air inlet branch pipe (72) with two open ends and used for introducing indoor air, and the two air inlet branch pipes are obliquely arranged, connected at the bottom and connected with the second box body (3).

9. The range hood of claim 8, wherein: first air inlet branch pipe (71) periphery is provided with first temperature sensor (73) that is used for detecting outdoor air temperature, second air inlet branch pipe (72) periphery is provided with second temperature sensor (74) that are used for detecting indoor air temperature, air-supply line (7) still include according to two temperature sensor's signal to make first air inlet branch pipe (71) and second air inlet branch pipe (72) only have one at the same time with valve block (75) of second box (3) interior intercommunication, valve block (75) set up the junction at first air inlet branch pipe (71) and second air inlet branch pipe (72).

10. The range hood according to any one of claims 1 to 5, wherein: the fresh air device further comprises an air filter (10), and the air filter (10) is arranged on the upstream of the second fan (6) on the air flow path.

11. A method for controlling introduction of fresh air into the range hood according to claim 8 or 9, wherein: the method comprises the following steps:

1) starting the range hood;

2) setting a desired temperature value X;

3) the first temperature sensor (73) detects the current outdoor air temperature X1, the second temperature sensor (74) detects the current indoor air temperature X2, the detected current temperature value is compared with the set temperature value, the difference value A between the outdoor air temperature and the set temperature value is | X1-X |, the difference value B between the indoor air temperature and the set temperature value is | X2-X |, and the sizes of A and B are judged:

3.1) if A is less than or equal to B, the valve plate (75) closes the second air inlet branch pipe (72), the first air inlet branch pipe (71) is communicated with the second box body (3), and fresh air is introduced from the outside;

3.2) if A is larger than B, the valve plate (75) closes the first air inlet branch pipe (71), the second air inlet branch pipe (72) is communicated with the second box body (3), and fresh air is introduced from the indoor space.

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