CN217441737U - Fume exhaust fan - Google Patents

Abstract

The utility model discloses a range hood, including collection petticoat pipe, setting in the fan frame of collection petticoat pipe top and the fan system of setting in the fan frame, the air intake has been seted up on the collection petticoat pipe, air intake department is provided with fixed filter screen, the below that the fan system is located in the fan frame is provided with moves the filter screen, move and seted up the mesh on the filter screen, pass through curved water conservancy diversion arc transition between the adjacent mesh, move the filter screen and can remove and rotate along the non-dead axle of the axis of rotation that extends around to change and the fixed filter screen between interval and the angle, the rotation switching-over of moving the filter screen makes the bellying of water conservancy diversion arc switch between windward side and leeward side. Compared with the prior art, the utility model has the advantages of: through making movable filter screen portable and rotation switching-over, realize controlling passageway flow control and resistance distribution in the fan frame, the multiple user culinary art condition of abundant adaptation improves the adaptability of product to changing the culinary art operating mode under the unchangeable condition of amount of wind noise.

Description

Fume exhaust fan

Technical Field

The utility model relates to an oil smoke purifier, especially a range hood.

Background

The range hood has become one of the indispensable kitchen household electrical appliances in modern families. The range hood works by utilizing the fluid dynamics principle, sucks and exhausts oil smoke through a centrifugal fan arranged in the range hood, and filters partial grease particles by using a filter screen. The centrifugal fan comprises a volute, an impeller arranged in the volute and a motor driving the impeller to rotate. When the impeller rotates, negative pressure suction is generated in the center of the fan, oil smoke below the range hood is sucked into the fan, accelerated by the fan and then collected and guided by the volute to be discharged out of a room.

The top-suction type range hood adopts an oil smoke rising principle, a negative pressure area is generated right above a cooking bench to suck and exhaust naturally rising oil smoke generated during cooking, and the range hood has the advantages of fashionable and concise appearance, larger air volume, larger space and capability of capturing the oil smoke far away from the cooking bench, and has the defects that the installation height is far away from the cooking bench, and the oil smoke above a pot is easy to be disturbed by ambient air to cause the escape of the oil smoke to the periphery under the cooking state with small oil smoke volume, so that the oil smoke suction effect is poor.

Therefore, a smoke guide plate is generally arranged below an air inlet of the top-suction range hood to form an annular suction structure, and the effect of sucking the oil smoke is improved by utilizing the coanda effect. The top suction type range hood with the smoke guide plate disclosed in the chinese patent with the application number of 201410419676.4 comprises a body, a smoke collecting hood and the smoke guide plate, wherein the smoke collecting hood is connected with the body, a fan is arranged in the body, an air inlet is arranged on the smoke collecting hood, the smoke guide plate is arranged right opposite to the air inlet of the smoke collecting hood and fixed on the smoke collecting hood through a bracket or a buckle, and a distance exists between the smoke guide plate and the smoke collecting hood to form a smoke channel.

Because the range hood adopting the smoke guide plate does not drip oil and has better oil smoke absorption effect, the range hood has more and more extensive application in recent years. The existing range hood adopting the smoke guide plate often has the following disadvantages:

1. when the traditional range hood is used on a common double stove, the difference between the smoke quantity generated by the quick-frying side and the soup cooking side is large, and the air quantity or the area of an air inlet cannot be adjusted to adapt to the cooking condition;

2. although the air inlet of some range hoods is adjusted along with the size of oil smoke, two sets of driving motors are generally needed to realize the adjustment respectively, so that the cost is high, the stability is poor, and the popularization difficulty is high.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that to the not enough of above-mentioned prior art existence, provide a range hood, can realize that the distribution of air inlet region and resistance comes the adaptation culinary art condition, promote the oil absorption cigarette effect.

The utility model provides a technical scheme that above-mentioned technical problem adopted does: the utility model provides a range hood, includes collection petticoat pipe, sets up in the fan frame of collection petticoat pipe top and sets up the fan system in the fan frame, the air intake has been seted up on the collection petticoat pipe, air intake department is provided with fixed filter screen, its characterized in that:

the below that lies in fan system in the fan frame is provided with moves the filter screen, move and seted up the mesh on the filter screen, pass through curved water conservancy diversion arc transition between the adjacent mesh, move the filter screen and can remove about and rotate along the non-dead axle of the axis of rotation that extends around to change and fixed filter screen between interval and the angle, the rotation switching-over that moves the filter screen makes the protruding face of water conservancy diversion arc switch between windward side and leeward side.

In order to facilitate the translation and the rotation reversing of the movable filter screen, the range hood further comprises a movement mechanism for driving the movable filter screen to move, the movement mechanism comprises a mounting plate, a first central shaft and a second central shaft, the mounting plate is fixed in the fan frame, a first guide groove and a second guide groove are formed in the mounting plate, the first guide groove is circular, the second guide groove is positioned at the periphery of the first guide groove and is an equilateral triangle, the first guide groove forms an inscribed circle of the second guide groove, the two guide grooves are communicated at the tangent position, the first central shaft and the second central shaft are respectively fixed with the movable filter screen, the first central shaft and the second central shaft can move along the first guide groove and the second guide groove, and when one of the first central shaft and the second central shaft moves from the tangent position of the two guide grooves to the corresponding vertex of the second guide groove, the other of the first central shaft and the second central shaft enters the first guide groove from the tangency of the two guide grooves and moves along the first guide groove.

Preferably, in order to facilitate the movement of the two center shafts, the moving mechanism further includes a driving gear rotatably provided on the mounting plate and having a rotation axis extending in the front-rear direction, first guide grooves are disposed at intervals on an outer circumference of the driving gear and concentric with the driving gear, the first and second driven gears are sector gears disposed at intervals and having teeth distributed on sides distant from each other, the first center shaft is fixed to the first driven gear, the second center shaft is fixed to the second driven gear, the rack has two teeth and is connected between ends corresponding to sectors of the two driven gears, respectively, teeth of the two racks are disposed on sides distant from each other, and the teeth of the rack and the teeth of the two driven gears are smoothly transitioned to be integrated, the first driven gear, the second driven gear and the rack thereby constitute an integrated profile gear having two central axes, which is meshed with the drive gear.

In order to guide the rear driven gear to enter the first guide groove, accommodating grooves are formed in the mounting plate, and the accommodating grooves are located on the outer side, far away from the first guide groove, of the second guide groove and are communicated with each other; the movement mechanism further comprises a guide rod, the guide rod is rotatably arranged in the second guide groove and the accommodating groove through a rotating shaft, and the rotating axis of the guide rod extends along the front-back direction; each guide rod corresponds to one side of the second guide groove, which is tangent to the first guide groove, and the guide rods are far away from each other; the guide rod is provided with a first end part and a second end part which are opposite, the first end part is close to the vertex of the second guide groove, the second end part is close to the tangent position of the second guide groove and the first guide groove, the first end part of the guide rod keeps the trend of being positioned in the second guide groove, and the second end part of the guide rod keeps the trend of being positioned in the accommodating groove; the first central shaft and the second central shaft can abut against the part, located between the rotating shaft and the first end part, of the guide rod, so that the second end part of the guide rod rotates into the second guide groove to block the second guide groove.

In order to facilitate the second end portion of the guide rod to be located in the accommodating groove and avoid blocking the second guide groove, so that the driven gear at the front end can enter, the moving mechanism further comprises a reset piece, the reset piece is arranged between the second end portion of the guide rod and the accommodating groove, and each reset piece corresponds to the second end portion of the guide rod, so that the second end portion of the guide rod tends to be located in the accommodating groove.

Preferably, the reset piece is an elastic piece or a magnetic piece.

Compared with the prior art, the utility model has the advantages of: the movable filter screen can move and rotate for reversing, flow regulation and resistance distribution of left and right channels in the fan frame are realized, and the movable filter screen is cooperated with the change of the air inlet proportion, so that the cooking condition of various users is fully adapted, and the adaptability of the product to the change of the cooking condition under the condition of constant air volume noise is improved; the combination of the meshing rotation of the special-shaped gears and the guide groove is utilized, the reversing of the movable filter screen can be realized without an additional mechanism, the stability of the movement mechanism is high, and the cost is low.

Drawings

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

fig. 2 is a sectional view of a range hood according to an embodiment of the present invention in a first state;

FIG. 3 is a schematic view of a dynamic filter screen and a movement mechanism thereof of the range hood of FIG. 2;

FIG. 4 is an exploded view of the dynamic filter screen and its moving mechanism of FIG. 3;

FIG. 5 is a cross-sectional view of the dynamic screen of FIG. 3 and its motion mechanism;

FIG. 6 is an enlarged view of a portion I of FIG. 5;

fig. 7 is a sectional view of the range hood according to the embodiment of the present invention in the second state;

FIG. 8 is a schematic view of the dynamic screen of FIG. 7 and its motion mechanism;

FIG. 9 is a cross-sectional view of the dynamic screen of FIG. 8 and its motion mechanism;

FIG. 10 is an enlarged view of portion II of FIG. 9;

fig. 11 is a sectional view of the range hood according to the embodiment of the present invention in the third state;

FIG. 12 is a schematic view of the dynamic screen of FIG. 11 and its motion mechanism;

fig. 13 is a schematic view of the range hood according to the embodiment of the present invention in a fourth state;

FIG. 14 is a schematic view of the dynamic screen of FIG. 13 and its motion mechanism;

fig. 15 is a schematic view of the range hood according to the embodiment of the present invention in a fifth state;

FIG. 16 is a schematic view of the dynamic screen of FIG. 15 and its motion mechanism;

fig. 17 is a schematic view of the range hood according to the embodiment of the present invention in a sixth state;

FIG. 18 is a schematic view of the dynamic screen of FIG. 17 and its motion mechanism;

fig. 19 is a schematic view of the range hood according to the embodiment of the present invention in a seventh state;

fig. 20 is a schematic view of the dynamic screen of fig. 19 and its motion mechanism.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar functions.

In the description of the present invention, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in a generic and descriptive sense only and not for purposes of limitation, as the disclosed embodiments of the invention may be oriented in different directions and the directional terms are intended to be illustrative and should not be construed as limiting, such as "upper" and "lower" are not necessarily limited to directions opposite to or coincident with the direction of gravity. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

Referring to fig. 1 to 6, a range hood, which is a ceiling range hood, includes a fume collecting hood 1 and a fan frame 2 disposed above the fume collecting hood 1, and a fan system 3 is disposed in the fan frame 2. The smoke collecting cover 1 is provided with an air inlet 11, so that the oil smoke can enter the fan frame 2 from the air inlet 11 in the upward rising process and is discharged by the fan system 3. The bottom of the fume collecting hood 1 is upwards sunken to form a fume collecting cavity 12, and the air inlet 11 is positioned at the top of the fume collecting cavity 12.

The fan frame 2 is located below the fan system 3, that is, on the oil smoke flow path, and the upstream of the fan system 3 is provided with a movable filter screen 4 arranged at an upper and lower interval. The moving screen 4 is preferably flat, extends in the transverse direction and is movable inside the fan frame 2, so as to vary the resistance. A smoke guide plate 6 is arranged below the air inlet 11, and oil smoke enters the air fan frame 2 through the air inlet 11 from a channel between the periphery of the smoke guide plate 6 and the smoke collecting cover 1.

The movable filter screen 4 is provided with mesh holes 41, so that the movable filter screen 4 can form a grid net. Two adjacent meshs 41 pass through curved water conservancy diversion arc 42 transition between, and during forward, water conservancy diversion arc 42 is protruding towards the oil smoke, constitutes for the windward side, and during backward, water conservancy diversion arc 42 is protruding to be kept away from the oil smoke, constitutes for the leeward side. The width of the movable filter screen 4 in the left-right direction is smaller than that of the fan frame 2 in the left-right direction. The air inlet 11 is provided with a fixed filter screen 5, and the movable filter screen 4 is located at the downstream of the fixed filter screen 5, namely, the movable filter screen 4 is located between the fixed filter screen 5 and the fan system 3. The fixed screen 5 is in the present embodiment in the form of an inverted cone with a smaller bottom and a larger top, and alternatively, may be in the form of another existing screen. The smoke guide plate 6 is positioned below the fixed filter screen 5.

The fan frame 2 is also internally provided with a movement mechanism for driving the movable filter screen 4 to move, is positioned between the fan system 3 and the fixed filter screen 5, and comprises a mounting plate 71, a driving gear 72, a first driven gear 73, a second driven gear 74, a rack 75, a guide rod 76, a resetting piece 77 and a driving mechanism 78. Wherein the mounting plate 71 is fixed inside the fan frame 2, it may be fixed directly or indirectly with the fan frame 2, in this embodiment it is fixed at the rear side inside the fan frame 2. The drive gear 72 is rotatably provided on the mounting plate 71, in this embodiment, on the front side of the mounting plate 71. The driving mechanism 78 is used to drive the driving gear 72 to rotate, the rotation axis of the driving gear 72 extends in the front-rear direction, and the driving mechanism 78 is preferably a motor. The first driven gear 73 and the second driven gear 74 are sector gears provided at intervals, and teeth of the respective driven gears are distributed on sides away from each other. A first center shaft 731 is fixed to the center of the first driven gear 73, the first center shaft 731 passes through both ends of the first driven gear 73 in the axial direction, and similarly, a second center shaft 741 is fixed to the center of the second driven gear 74, and the second center shaft 741 passes through both ends of the second driven gear 74 in the axial direction. Preferably, the first driven gear 73 and the second driven gear 74 are symmetrically disposed. The two racks 75 are respectively connected between the fan-shaped corresponding ends of the two driven gears, the teeth of the two racks 75 are disposed at sides away from each other, and the teeth of the racks 75 are integrated with the teeth of the two driven gears in a smooth transition, whereby the first driven gear 73, the second driven gear 74, and the racks 75 constitute an integrated special-shaped gear having two central axes, which is kept meshed with the drive gear 72. The first driven gear 73 and the second driven gear 74 are fixed to the movable screen 4, respectively, and in this embodiment, to the rear end of the movable screen 4. Preferably, the central shafts of the two driven gears are fixed with the dynamic filter screen 4.

A first guide groove 711 and a second guide groove 712 are formed on the mounting plate 71 to be recessed rearward from the front surface, wherein the first guide groove 711 is formed in a circular shape, is arranged at intervals on the outer circumference of the driving gear 72, and is concentric with the driving gear 72. The second guide groove 712 is located at the outer periphery of the first guide groove 711, and has an equilateral triangle shape, and the first guide groove 711 forms an inscribed circle of the second guide groove 712, and the two guide grooves communicate at a tangent. Both the first center shaft 731 of the first driven gear 73 and the second center shaft 741 of the second driven gear 74 are movable along the first guide groove 711 and the second guide groove 712.

The mounting plate 71 further has a receiving groove 713 formed thereon, and the receiving groove 713 is located outside the second guide groove 712 away from the first guide groove 711 and communicates with each other. The guide bar 76 is rotatably disposed in the second guide groove 712 and the accommodating groove 713 via a rotating shaft 761, and a rotation axis of the guide bar 76 extends in the front-rear direction. Each guide bar 76 corresponds to one side of the second guide groove 712 tangent to the first guide groove 711, and the guide bars 76 are far away from each other, i.e., not close to the same vertex of the triangle. The guide bar 76 has a first end 762 and a second end 763 opposite to each other, wherein the first end 762 is close to the vertex of the second guide groove 712, and the second end 763 is close to the tangent of the second guide groove 712 and the first guide groove 711. The restoring member 77 is disposed between the second end portion 763 of the guide lever 76 and the second guide groove 712, and the restoring member 77 may be an elastic member or a magnetically attracted magnet, etc., so that the first end portion 762 of the guide lever 76 tends to remain located in the second guide groove 712 and the second end portion 763 of the guide lever 76 tends to remain located in the accommodating groove 713. Each reset member 77 corresponds to the second end 763 of the guide bar 76.

When the drive mechanism 78 drives the drive gear 72 to rotate, the shaped gear moves along the two guide grooves and rotates relative to the drive gear 72. Referring to fig. 3, when the central axes of the first driven gear 73 and the second driven gear 74 are located in the bottom edge of the second guide groove 712, the first driven gear 73 starts to enter the region where the guide rod 76 is located, the first driven gear 73 is engaged with the driving gear 72, and after a certain distance, when the first central axis 731 of the first driven gear 73 presses against the portion (which may be pressed all the way or only against the portion near the first end 762) between the first end 762 of the guide rod 76 and the rotating shaft 761, the guide rod 76 is rotated relative to the mounting plate 71 against the resetting force of the resetting member 77, so that the second end 763 of the guide rod 76 is rotated and compensated into the second guide groove 712 to block the second guide groove 712, and at this time, the second driven gear 74 moves to a tangent point, so that the second driven gear 74 cannot move continuously along the second guide groove 712, but moves upwards and continuously along the first guide groove 711, see fig. 9. Thereafter, the second driven gear 74 is engaged with the driving gear 72 to reverse the moving process, and referring to fig. 12 and 14, the second driven gear 74 enters the left side of the second guide groove 712 first, and the first driven gear 72 enters the first guide groove 711. And then the position of the special-shaped gear is changed in a circle of rotation along the two guide grooves (the movable filter screen 4 rotates in a non-fixed shaft mode), and the reversing of the movable filter screen 4 is realized after the special-shaped gear rotates for a circle.

In the in-service use, the cooking utensils unilateral under the range hood explodes the condition of stir-fry more, but is not other one side do not use or do not have into the cigarette, and its culinary art state can switch between big small cigarette, and oil strain ability and resistance are its relevant a pair of contradiction, hardly compromise the two on ordinary range hood, and the utility model discloses in, come to adjust filter screen clearance and angle between fixed filter screen 5 and the movable filter screen 4 according to the operating mode oil smoke condition, and then change resistance and oil strain ability, solve big oil smoke and need the big amount of wind and can ignore the oil strain temporarily, the contradiction of oil strain needs to be solved in the key to little oil smoke, realizes that big cigarette priority guarantees oil smoke absorption ability, and little cigarette priority guarantees oil strain ability.

In addition: the large and small flow rate is the actual working state flow rate of the range hood installed at the home of a user, and the large and small flow rate dividing line can be defined to be 6-10m according to the laboratory test condition ³ The flow limit of the ceiling-mounted range hood which is installed according to the standard (the installation range is 650-750mm defined by national standard) and is 700mm away from the platform surface can be 9m according to the slight difference between different on-hook heights and machine types ³ And when the installation height is adjusted to 750mm, the boundary line needs to be lifted to about 10 to reduce the escape of oil smoke.

Referring to fig. 2 and 3, the left and right sides difference is less, the left side oil smoke is main, the less culinary art state of whole oil smoke, moves filter screen 4 horizontal extension this moment and incline to the right side, increase right side resistance for main flow is on the left (more unobstructed), moves the water conservancy diversion arc 42 of filter screen 4 this moment and is located the bottom, is in the forward state, and the resistance is less.

Referring to fig. 7 and 8, the left and right sides difference is less, the right side oil smoke is main, the partial little culinary art state of whole oil smoke, moves filter screen 4 horizontal extension this moment and incline to the left side, increase left side resistance for main flow is on the left side (more unobstructed), and the water conservancy diversion arc 42 that moves filter screen 4 this moment is located the bottom, is in the forward state, and the resistance is less. Vice versa, see fig. 19 and 20.

Referring to fig. 11 and 12, compared to the state shown in fig. 7, the oil smoke on the right side is larger than that on the left side, and at this time, the movable filter screen 4 extends laterally (slightly inclines) and is biased to the left side, so that the resistance on the left side is increased, the main flow rate is on the left side (is more unobstructed), and at this time, the guiding arc 42 of the movable filter screen 4 is located at the bottom and is in the positive state, and the resistance is smaller.

Referring to fig. 13 and 14, in a cooking state shown in fig. 7, the right side has larger oil smoke than the left side, and the whole oil smoke is larger, at this time, the movable filter screen 4 is inclined upward from left to right and is located on the left side gradually, so that the resistance on the left side is increased, the main flow is on the right side, the guide arc 42 of the movable filter screen 4 is located at the bottom and is in a forward state, and the resistance is smaller; at this time, the left end of the movable screen 4 is a front end and the right end is a rear end, and then, the movement is continued, the direction adjustment is started, the current front end (the end corresponding to the first driven gear 73) is changed into the rear end, the current rear end (the end corresponding to the second driven gear 74) is changed into the front end, and the front end enters the second guide groove 712, and the movement process is as described above.

Referring to fig. 15 and fig. 16, in a cooking state shown in fig. 11, the right side has a larger oil smoke than the left side, and the whole oil smoke is larger, at this time, the movable filter screen 4 is inclined upward from left to right and is located on the left side gradually, so that the main flow is on the right side, the movable filter screen 4 is parallel to the left side of the second guide groove 712 at this time, so that the resistance of the whole machine is mainly caused by the fixed filter screen 5, the resistance of the movable filter screen 4 is small, at this time, the flow guide arc 42 of the movable filter screen 4 is located at the bottom and is in a forward state, the resistance is small, and the movable filter screen 4 completes 120-degree adjustment relative to the state shown in fig. 2.

Referring to fig. 17 and 18, the cooking state is opposite to that shown in fig. 15, at this time, the movable filter screen 4 is gradually tilted downward from left to right and located on the right side, so that the main flow is on the right side, the movable filter screen 4 is parallel to the right side of the second guide groove 712 at this time, so that the resistance of the whole machine is mainly caused by the fixed filter screen 5, the resistance of the movable filter screen 4 is small, the flow guide arc 42 of the movable filter screen 4 is in the reverse state at this time, the resistance is slightly larger than the windward side, the movable filter screen 4 is adjusted by 240 ° relative to the state shown in fig. 2, and then the end of the movable filter screen 4 corresponding to the first driven gear 73 is changed to the front end again, and the end corresponding to the second driven gear 74 is changed to the rear end again.

Claims (6)

1. The utility model provides a range hood, includes collection petticoat pipe (1), sets up fan frame (2) and fan system (3) of setting in fan frame (2) in collection petticoat pipe (1) top, air intake (11) have been seted up on collection petticoat pipe (1), air intake (11) department is provided with fixed filter screen (5), its characterized in that:

the utility model discloses a fan system, including fan frame (2), the below that is located fan system (3) is provided with moves filter screen (4), move and seted up mesh (41) on the filter screen (4), pass through curved water conservancy diversion arc (42) transition between adjacent mesh (41), move filter screen (4) and remove and rotate along the non-dead axle of axis of rotation that extends around can to change and fix interval and angle between filter screen (5), the rotation switching-over that moves filter screen (4) makes the bellying of water conservancy diversion arc (42) switch between windward side and leeward side.

2. The range hood of claim 1, wherein: the range hood further comprises a movement mechanism for driving the movable filter screen (4) to move, the movement mechanism comprises a mounting plate (71), a first central shaft (731) and a second central shaft (741), the mounting plate (71) is fixed in the fan frame (2), a first guide groove (711) and a second guide groove (712) are formed in the mounting plate (71), the first guide groove (711) is circular, the second guide groove (712) is located on the periphery of the first guide groove (711) and is in an equilateral triangle shape, the first guide groove (711) forms an inscribed circle of the second guide groove (712), the two guide grooves are communicated at a tangent position, the first central shaft (731) and the second central shaft (741) are respectively fixed with the movable filter screen (4), and both the first central shaft (731) and the second central shaft (741) can move along the first guide groove (711) and the second guide groove (712), when one of the first central axis (731) and the second central axis (741) moves from the tangency of the two guide grooves to the corresponding vertex of the second guide groove (712), the other of the first central axis (731) and the second central axis (741) enters the first guide groove (711) from the tangency of the two guide grooves and moves along the first guide groove (711).

3. The range hood of claim 2, wherein: the motion mechanism further comprises a driving gear (72), a first driven gear (73), a second driven gear (74) and a rack gear (75), the driving gear (72) is rotatably arranged on the mounting plate (71) and the rotation axis extends along the front and back direction, the first guide grooves (711) are arranged at intervals on the periphery of the driving gear (72) and are concentric with the driving gear (72), the first driven gear (73) and the second driven gear (74) are sector gears arranged at intervals, the teeth of the driven gears are distributed on the sides far away from each other, the first central shaft (731) is fixed with the first driven gear (73), the second central shaft (741) is fixed with the second driven gear (74), the rack gear (75) has two parts and is respectively connected between the fan-shaped corresponding ends of the two driven gears, the teeth of the two rack gears (75) are arranged on the sides far away from each other, and the teeth of the rack (75) and the teeth of the two driven gears are smoothly transited and integrated, so that the first driven gear (73), the second driven gear (74) and the rack (75) form an integrated special-shaped gear with two central shafts, and the special-shaped gear is meshed with the driving gear (72).

4. The range hood of claim 2, wherein: the mounting plate (71) is further provided with a containing groove (713), and the containing grooves (713) are positioned on the outer side, away from the first guide groove (711), of the second guide groove (712) and communicated with each other; the movement mechanism further comprises a guide rod (76), the guide rod (76) is rotatably arranged in the second guide groove (712) and the accommodating groove (713) through a rotating shaft (761), and the rotating axis of the guide rod (76) extends along the front-back direction; each guide rod (76) corresponds to one side of the second guide groove (712) tangent to the first guide groove (711), and the guide rods (76) are far away from each other; the guide bar (76) having opposite first and second ends (762, 763), the first end (762) being proximate to the apex of the second guide slot (712), the second end (763) being proximate to the tangent of the second guide slot (712) and the first guide slot (711), the first end (762) of the guide bar (76) remaining in the tendency of the second guide slot (712), the second end (763) of the guide bar (76) remaining in the tendency of the receiving slot (713); the first central shaft (731) and the second central shaft (741) can press against the part of the guide rod (76) between the rotating shaft (761) and the first end part (762), so that the second end part (763) of the guide rod (76) rotates into the second guide groove (712) to close the second guide groove (712).

5. The range hood of claim 4, wherein: the movement mechanism further comprises a resetting piece (77), the resetting piece (77) is arranged between the second end portion (763) of the guide rod (76) and the accommodating groove (713), and each resetting piece (77) corresponds to the second end portion (763) of the guide rod (76), so that the second end portion (763) of the guide rod (76) tends to be located in the accommodating groove (713).

6. The range hood of claim 5, wherein: the reset piece (77) is an elastic piece or a magnetic piece.

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