CN220707438U - Fume exhauster - Google Patents

Abstract

The utility model discloses a range hood, which comprises an air inlet piece, wherein the air inlet piece comprises an air inlet, and is characterized in that: the range hood further comprises a first fan arranged at the air inlet, the first fan is an oblique flow fan, the first fan comprises an impeller, the impeller comprises blades capable of adjusting angles to change air inlet directions, and the angles are inclined angles of the blades relative to the plane where the air inlet is located. Compared with the prior art, the utility model has the advantages that: through changing the angle of blade to can change the air inlet direction of air intake department, thereby change import negative pressure area and distribution area, adapt to the smoking demand under the different culinary art operating modes.

Description

Fume exhauster

Technical Field

The utility model relates to a lampblack purifying device, in particular to a range hood.

Background

With the improvement of living standard, the cooking environment is not limited to the kitchen, and people have the requirements of eating hot pot, barbecue and the like at home, so as to generate an environment similar to an open kitchen.

For adapting such an open environment, the island type range hood can be arranged above the cooking utensil to directly absorb and discharge oil smoke, and the island type range hood comprises a centrifugal fan, a smoke collecting hood and a flue, wherein an air inlet of the centrifugal fan is downwards and is opposite to an air inlet direction, the smoke can be collected to the air inlet from bottom to top along the air inlet direction, the smoke collecting hood is opposite to the air inlet of the centrifugal fan, the flue comprises a shell, and two ends of the shell are respectively connected with the smoke collecting hood and a volute of the centrifugal fan, so that the flue is communicated with an air outlet side of the smoke collecting hood and the air inlet of the centrifugal fan.

The scheme of the existing island type range hood is adopted to treat the oil smoke, the range hood is limited by a cooking environment, and the machine size cannot be too large, so that the range of the range hood for effectively capturing the oil smoke is smaller and the range is relatively fixed.

Disclosure of Invention

The utility model aims to solve the technical problem of providing a range hood capable of enlarging the range of capturing oil smoke aiming at the defects existing in the prior art.

The technical scheme adopted for solving the technical problems is as follows: the utility model provides a range hood, includes air inlet piece, air inlet piece includes air intake, its characterized in that: the range hood further comprises a first fan arranged at the air inlet, the first fan is an oblique flow fan, the first fan comprises an impeller, the impeller comprises blades capable of adjusting angles to change air inlet directions, and the angles are inclined angles of the blades relative to the plane where the air inlet is located.

Through changing the angle of blade to can change the air inlet direction of air intake department, thereby change import negative pressure area and distribution area, adapt to the smoking demand under the different culinary art operating modes.

In order to realize the angularly adjustable of blade, the impeller includes parallel and coaxial first bracket component and second bracket component that sets up in proper order by the direction of inboard side air intake on the air inlet piece, the blade includes the inlet end that sets up towards the air intake direction and the end of giving vent to anger that sets up towards the inboard direction of air inlet piece, inlet end and second bracket component swing joint, the end of giving vent to anger and first bracket component swing joint, first bracket component and second bracket component can do asynchronous rotation around the axial of first fan, first bracket component and second bracket component can also be close to each other in the axial and keep away from to change the angle of blade.

Preferably, the first bracket component comprises a first bracket body and a second bracket body which are both annular, the second bracket body is positioned at the outer side of the first bracket body, the first bracket component further comprises a first connecting bracket used for connecting the first bracket body and the second bracket body, the second bracket component comprises a third bracket body and a fourth bracket body which are both annular, the fourth bracket body is positioned at the outer side of the third bracket body, the second bracket component further comprises a second connecting bracket used for connecting the third bracket body and the fourth bracket body, two end parts of the air inlet end are respectively movably connected with the third bracket body and the fourth bracket body, and two end parts of the air outlet end are respectively movably connected with the first bracket body and the second bracket body.

In order to drive the impeller to rotate, the first fan further comprises a motor for driving the impeller to rotate, the motor is arranged on the inner side of the impeller, the motor comprises a motor body, a first support assembly and a second support assembly, the first support assembly is used for driving the first support assembly to rotate, the second support assembly is used for driving the second support assembly to rotate, the first support assembly and the second support assembly are respectively arranged on two opposite sides of the motor body, and the first support assembly is a telescopic shaft.

In order to realize the connection of the impeller and the first fan, the first fan further comprises a third connecting bracket for connecting the first shaft body and the first bracket component, and a fourth connecting bracket for connecting the second shaft body and the second bracket component.

In order to form the air inlet channel, the air inlet piece includes annular lateral wall, the air intake forms the inboard at the lateral wall, the lateral wall extends in the casing by the bottom of casing, first fan is including setting up the disk body subassembly at the radial inboard of impeller, the blade sets up between disk body subassembly and lateral wall, the space between one side that the disk body subassembly is close to the lateral wall and the lateral wall constitutes the air inlet channel of first fan.

In order to realize the shrink of disk body subassembly, the disk body subassembly includes movable disk body and fixed disk body, movable disk body and fixed disk body are arranged along the axial of impeller, movable disk body and fixed disk body are set gradually by first support subassembly to second support subassembly direction, movable disk body drives by first axis body and can stretch out outside the fixed disk body and retract the inboard of fixed disk body.

In order to realize the linkage of disk body subassembly and impeller, movable disk body is connected with the third linking bridge, fixed disk body is connected with the fourth linking bridge.

In order to provide the flow rate and the negative pressure, the range hood further comprises a second fan arranged at the downstream of the air inlet piece and used for providing the flow rate and the negative pressure on the flow path of the oil fume.

In order to filter the oil fume, on the flow path of the oil fume gas, the range hood further comprises a filter device which is arranged at the downstream of the air inlet piece and used for filtering the oil fume.

In order to be able to detect the change of the flue gas concentration, the air inlet piece is further provided with a flue gas concentration detection sensor for detecting the change of the flue gas concentration, so that the operation working condition of the first fan is adjusted.

In order to reduce the size of the air inlet, the main flow-passing area is dispersed, the flow velocity of the inlet is improved, the effective smoking area is enlarged, the oil smoke capturing effect is enhanced, and the air inlet piece further comprises a guide plate arranged on the radial inner side of the impeller.

Compared with the prior art, the utility model has the advantages that: through set up first fan in air intake department, promote the gas velocity of flow of air intake department, outwards enlarge negative pressure area, strengthen the oil smoke entrapment effect through two aspects of velocity of flow and negative pressure, the impeller of first fan can warp the compression in certain limit, changes the air inlet direction of fan import department through the blade deformation to change import negative pressure and go the area and distribute the region, adapt to the smoking demand under the different culinary art operating modes. Through setting up the guide plate to can reduce the size of air intake, make main overflow area dispersion, promote the import velocity of flow and enlarge effective smoking area simultaneously, strengthen the oil smoke entrapment effect. Through setting up fog concentration detection sensor, detect the operating mode of real-time control first fan through the fog concentration, give attention to user's use experience and oil smoke entrapment effect, extension filter equipment's life simultaneously.

Drawings

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

fig. 2 is a schematic bottom view of a range hood according to an embodiment of the present utility model;

fig. 3 is a cross-sectional view of the range hood according to the embodiment of the present utility model when the blades of the first fan are not adjusted in angle;

fig. 4 is a cross-sectional view of the range hood according to the embodiment of the present utility model after the blade adjustment angle of the first fan;

fig. 5 is a schematic top view of a first fan of the range hood according to an embodiment of the present utility model when the blade is not adjusted in angle;

fig. 6 is a schematic bottom view of a first fan of the range hood according to an embodiment of the present utility model when the blade is not adjusted in angle;

fig. 7 is a cross-sectional view of a first fan of the range hood according to an embodiment of the present utility model when the blades are not adjusted in angle;

fig. 8 is a schematic view of a first fan of the range hood according to an embodiment of the present utility model after adjusting an angle of a blade;

fig. 9 is a top view of a first fan of the range hood according to an embodiment of the present utility model after adjusting an angle of a blade;

fig. 10 is a sectional view of a first fan of the range hood according to an embodiment of the present utility model after an angle of a blade is adjusted;

fig. 11 is an enlarged view of a portion I of fig. 10.

Detailed Description

The utility model is described in further detail below with reference to the embodiments of the drawings.

In the description of the present utility model, it should 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", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for purposes of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and because the disclosed embodiments of the present utility model may be arranged in different orientations, these directional terms are merely for illustration and should not be construed as limitations, such as "upper", "lower" are not necessarily limited to orientations opposite or coincident with the direction of gravity. Furthermore, features defining "first", "second" may include one or more such features, either explicitly or implicitly.

Referring to fig. 1, a range hood comprises a housing 5, wherein the top of the housing 5 is connected with a suspended ceiling 200 through four steel wires 100, and is suitable for a space outside a kitchen, such as a scene which can be placed above a dining table 300 of a restaurant and used for eating chaffy dish, barbecue and the like and can generate oil smoke.

Referring to fig. 2 to 4, the inside of the housing 5 is provided with the filter device 3 and the air inlet member 1 in sequence from top to bottom, wherein the air inlet member 1 is arranged at the bottom of the housing 5. The air inlet piece 1 comprises an air inlet 11 which is arranged downwards, and the bottom of the shell 5 is opened at a position corresponding to the air inlet 11.

A first fan 2 is arranged at the air inlet 11. The first fan 2 is an oblique flow fan and comprises an impeller 21, the impeller 21 comprises a first bracket component 212 and a second bracket component 213 which are arranged in parallel, the first bracket component 212 and the second bracket component 213 are coaxially arranged on the air inlet piece 1 from top to bottom in sequence, and the shaft refers to the axis of the impeller 21 of the first fan 2.

Referring to fig. 5 to 10, the first bracket assembly 212 includes first and second brackets 2121 and 2122 each having a circular ring shape, the second bracket 2122 being spaced apart radially outward of the first bracket 2121, and the first bracket assembly 212 further includes a first connection bracket 2123 for connecting the first and second brackets 2121 and 2122. The first frame 2121 and the second frame 2122 are integrated by the first connecting bracket 2123.

The second bracket assembly 213 includes a third frame 2131 and a fourth frame 2132, both of which are ring-shaped, the fourth frame 2132 being positioned radially outward of the third frame 2131 at intervals, and the second bracket assembly 213 further includes a second connection bracket 2133 for connecting the third frame 2131 and the fourth frame 2132. The third frame 2131 and the fourth frame 2132 are integrated by the second connection bracket 2133.

The impeller 21 further includes at least two blades 211 disposed between the first bracket assembly 212 and the second bracket assembly 213, the blades 211 being spaced apart along the circumference of each bracket assembly. Each blade 211 includes an inlet end 2111, an inlet and an outlet end 2112. Two ends of the air inlet end 2111 in the radial direction are respectively and movably connected with a third frame 2131 and a fourth frame 2132 at corresponding positions, and two ends of the air outlet end 2112 in the radial direction are respectively and movably connected with a first frame 2121 and a second frame 2122 at corresponding positions.

The first fan 2 further includes a motor 22 for driving the impeller 21 to rotate, the motor 22 is disposed on the inner side of the impeller 21, and is a dual output motor, and the motor 22 includes a motor body 221, a first shaft 222 and a second shaft 223. The motor body 221 is flat. The first shaft body 222 and the second shaft body 223 are respectively disposed on two opposite sides of the motor body 221, the first shaft body 222 extends upward to be disposed corresponding to the first bracket assembly 212, and the second shaft body 223 extends downward to be disposed corresponding to the second bracket assembly 213. The first fan 2 further includes a third connection bracket 23 for connecting the first shaft body 222 and the first bracket assembly 212, and a fourth connection bracket 24 for connecting the second shaft body 223 and the second bracket assembly 213.

The first shaft body 222 and the second shaft body 223 can drive the first bracket component 212 and the second bracket component 213 to synchronously or asynchronously rotate, when the first bracket component 212 and the second bracket component 213 do not synchronously rotate, the first bracket component 212 and the second bracket component 213 deflect circumferentially, so that the inclination angle of the blade 211 changes, and the angle refers to the inclination angle of the plane where the blade 211 and the air inlet 11 are located, in this embodiment, the inclination angle between the blade 211 and the horizontal plane. The first bracket assembly 212 and the second bracket assembly 213 rotate around the axial direction of the first fan 2, which is the vertical direction in this embodiment. In addition, the first shaft body 222 is a telescopic shaft, and can also drive the first bracket component 212 to move relative to the second bracket component 213 in the axial direction. The first bracket assembly 212 and the second bracket assembly 213 can deflect in a radial direction, and the first bracket assembly 212 and the second bracket assembly 213 can move toward and away from each other in an axial direction, so that the inclination angle of the vane 211 can be changed to change the intake wind direction at the air intake 11.

Referring to fig. 3 to 11, the air intake member 1 includes an annular side wall 12, the air intake 11 is formed inside the side wall 12, and the side wall 12 extends from the bottom of the housing 5 into the housing 5. The first fan 2 further includes a tray assembly 25 disposed radially inward of the impeller 21, and the blades 211 are disposed between the tray assembly 25 and the side wall 12, and a space between a side of the tray assembly 25 adjacent to the side wall 12 and the side wall 12 constitutes an air intake passage 26 of the first fan 2.

The disc assembly 25 includes a movable disc 251 and a fixed disc 252, the movable disc 251 and the fixed disc 252 are disposed along an axial direction of the impeller 21, the movable disc 251 and the fixed disc 252 are sequentially disposed from the first bracket assembly 212 to the second bracket assembly 213, the movable disc 251 is connected with the third connecting bracket 23, and the fixed disc 252 is connected with the fourth connecting bracket 24. The movable tray 251 is driven by the first shaft 222 to extend out of the fixed tray 252 and retract into the inner side of the fixed tray 252. The extension and retraction of the movable tray 251 relative to the fixed tray 252 may be adapted to the distance between the two bracket assemblies, thereby allowing the height of both sides of the air inlet channel 26 to be adapted.

Referring to fig. 7-11, the first bracket assembly 212 may deflect relative to the second bracket assembly 213 to a range of (0, 8) optionally, the reference angle, i.e., the relative non-deflection of the two bracket assemblies, may be the corresponding non-deflection between the third and fourth connecting brackets 23, 24. The first and second bracket assemblies 212, 213 may have a number of 20-40 blades 211 disposed therebetween, the corners of the blades 211 may be hingedly connected to the first and second bracket assemblies 212, 213. The thickness of the flat motor 22 may be no more than 20mm, the diameter may be no more than 120mm, the first shaft 222 of the motor 22 may be folded inwardly, the retraction range may be 0-26 mm, the inner side of the blades 211 may be the flow path tray assembly 25, the movable tray 251 of the tray assembly 25 may be folded downwardly relative to the fixed tray 252, when the first bracket assembly 212 deflects relative to the second bracket assembly 213 (e.g., the two bracket assemblies rotate in the same direction but at different angles, or one bracket assembly does not rotate and the other bracket assembly rotates, or both bracket assemblies rotate in opposite directions), the middle blade 211 deflects accordingly, and simultaneously, according to the deflection direction of the blade 211, the first shaft 222 of the motor 22 begins to retract inwards or extend outwards to drive the movable plate 251 to retract downwards or extend upwards, thereby changing the installation angle of the blade 211, changing the air inlet direction and adjusting the distribution of the inlet negative pressure area, and in order to realize the deflection of the bracket assemblies, the output ends of the first shaft 222 and the second shaft 223 can be provided with a clutch, or different speed reducing mechanisms can be provided, A transmission mechanism, etc. Alternatively, two motors may be provided, each driving one of the carriage assemblies to effect deflection.

Referring to fig. 3 to 4, a filter device 3 for filtering oil smoke and a second fan 4 are further arranged on the inner side of the shell 5, the second fan 4 is a main motor of the range hood, and negative pressure is provided for oil smoke. On the flow path of the oil smoke gas, a filter device 3 is arranged at the downstream of the air inlet piece 1, and a second fan 4 is arranged at the downstream of the filter device 3.

Preferably, the second fan 4 is a centrifugal fan, the fan is used for air inlet from the lower part and air outlet from the circumferential direction, and then is guided by an air duct to be used for air outlet from the top of the machine. The filtering device 3 mainly comprises an active carbon adsorption layer, and is used for adsorbing and filtering the passing smoke to remove grease, moisture and partial tiny particles.

The bottom of the air inlet piece 1 is provided with a smoke concentration detection sensor 6 for detecting smoke concentration change at the periphery of the air inlet 11. Through detecting the operating mode of real-time control first fan 2 to smog concentration, give attention to user's use experience and oil smoke entrapment effect, extension filter equipment 3's life simultaneously.

The air inlet piece 1 further comprises a guide plate 7 arranged on the radial inner side of the impeller 21 and corresponding to the air inlet 11, namely positioned at the bottom of the air inlet piece 1. The guide plate 7 can reduce the size of the air inlet 11, so that the main flow passing area is dispersed, the flow speed of the inlet is improved, the effective smoking area is enlarged, and the oil smoke capturing effect is enhanced.

Through set up first fan 2 in air intake 11 department, can promote the gas velocity of flow of air intake 11 department, outwards enlarge negative pressure district area, through the oil smoke entrapment effect of strengthening in two aspects of velocity of flow and negative pressure, the flue gas of below is caught to do work through the first fan 2 of air intake 11 and accelerate, convey to filter equipment 3. The first fan 2 adopts a flat motor 22, the impeller 21 can deform and compress in a certain range, and the air inlet direction of the inlet of the fan is changed through the deformation of the blades, so that the negative pressure area and the distribution area of the inlet are changed, and the smoking requirements under different cooking conditions are met.

When cooking is carried out below the range hood, the smoke concentration detection sensor 6 positioned at the air inlet 11 starts to feed back the smoke distribution condition, and meanwhile the range hood starts to operate, and the second fan 4 positioned above provides flow and negative pressure for the lower part. The air inlet area is reduced by the guide plate 7, the flue gas flow speed is increased, the air flow at the air inlet 11 is accelerated by the first fan 2 positioned below, negative pressure is downwards transmitted, a negative pressure area is formed outside the air inlet 11, and the negative pressure area corresponds to an effective oil fume collecting range.

Because the density of hot air is low and the initial speed of the oil smoke exists, the oil smoke can rise upwards and gradually spread after being generated, and can expand rapidly after a certain position, and the range of a negative pressure area is required to be as large as possible for a better smoke capturing effect, and meanwhile, the gas flow rate is high.

The lampblack concentration is recorded as J, the deflection angle alpha of the first bracket component 212, the height of the first shaft body 222 is h, and the initial measurement of the range hood gear is to switch the corresponding lampblack concentration to J1 and J2.

When the cooking is performed by using small fire (J < J1), the generated oil smoke is less and relatively concentrated, the range of the oil smoke capturing is relatively concentrated by adopting the working condition shown in the following figure 7, wherein the included angle between the blade 211 and the horizontal direction is relatively large, and the better smoke capturing effect can be realized by adopting the smaller air quantity.

When the oil smoke is increased (J1 is less than J2), the smoke concentration detection sensor 6 detects that the value is changed, the air quantity corresponding to the second fan 4 is increased, the first bracket component 212 of the first fan 2 begins to deflect relative to the second bracket component 213, the first shaft body 222 of the motor 22 is contracted inwards, the movable disc body 251 begins to contract downwards, and the requirements are met

k1 K2 is a constant coefficient.

When cooking with big oil smoke (J2 < J), such as eating chafing dish, roasting, etc. or when external air flow disturbance occurs, the range hood adopts the most extreme working condition, see fig. 10, the first bracket component 212 deflects 8 degrees relative to the first bracket component 213, the movable disk 251 is completely contracted into the fixed disk 252, and meanwhile, the rotation speed of the second fan 4 above is increased, the air quantity is increased, and the smoke discharging effect is enhanced.

Claims (12)

1. The utility model provides a range hood, includes air inlet piece (1), air inlet piece (1) include air intake (11), its characterized in that: the range hood further comprises a first fan (2) arranged at the air inlet (11), the first fan (2) is an oblique flow fan, the first fan (2) comprises an impeller (21), the impeller (21) comprises blades (211) capable of adjusting the angle to change the air inlet direction, and the angle is the inclination angle of the blades (211) relative to the plane where the air inlet (11) is located.

2. The range hood of claim 1, wherein: the impeller (21) comprises a first support assembly (212) and a second support assembly (213) which are parallel and coaxially arranged, the first support assembly (212) and the second support assembly (213) are sequentially arranged on the air inlet piece (1) from the inner side to the air inlet (11), the blade (211) comprises an air inlet end (2111) arranged towards the air inlet (11) and an air outlet end (2112) arranged towards the inner side of the air inlet piece (1), the air inlet end (2111) is movably connected with the second support assembly (213), the air outlet end (2112) is movably connected with the first support assembly (212), the first support assembly (212) and the second support assembly (213) can rotate in an asynchronous mode around the axial direction of the first fan (2), and the first support assembly (212) and the second support assembly (213) can be mutually close to and far away from each other in the axial direction, so that the angle of the blade (211) can be changed.

3. The range hood of claim 2, wherein: the first support assembly (212) comprises a first support body (2121) and a second support body (2122) which are both annular, the second support body (2122) is located on the outer side of the first support body (2121), the first support assembly (212) further comprises a first connecting support (2123) used for connecting the first support body (2121) and the second support body (2122), the second support assembly (213) comprises a third support body (2131) and a fourth support body (2132) which are both annular, the fourth support body (2132) is located on the outer side of the third support body (2131), the second support assembly (213) further comprises a second connecting support (2133) used for connecting the third support body (2131) and the fourth support body (2132), two end portions of the air inlet end (2111) are movably connected with the third support body (2131) and the fourth support body (2132) respectively, and two end portions of the air outlet end portion (2122) are movably connected with the first support body (2131) and the second support body (2132) respectively.

4. The range hood of claim 2, wherein: the first fan (2) further comprises a motor (22) for driving the impeller (21) to rotate, the motor (22) is arranged on the inner side of the impeller (21), the motor (22) comprises a motor body (221), a first shaft body (222) for driving the first bracket component (212) to rotate and a second shaft body (223) for driving the second bracket component (213) to rotate, the first shaft body (222) and the second shaft body (223) are respectively arranged on two opposite sides of the motor body (221), and the first shaft body (222) is a telescopic shaft.

5. The range hood of claim 4, wherein: the first fan (2) further comprises a third connecting bracket (23) for connecting the first shaft body (222) and the first bracket component (212), and a fourth connecting bracket (24) for connecting the second shaft body (223) and the second bracket component (213).

6. A range hood according to claim 5, wherein: the air inlet piece (1) comprises an annular side wall (12), the air inlet (11) is formed in the inner side of the side wall (12), the side wall (12) extends from the bottom of the shell (5) to the inside of the shell (5), the first fan (2) comprises a disc body assembly (25) arranged on the radial inner side of the impeller (21), the blades (211) are arranged between the disc body assembly (25) and the side wall (12), and an air inlet channel (26) of the first fan (2) is formed in a space between one side, close to the side wall (12), of the disc body assembly (25) and the side wall (12).

7. The range hood of claim 6, wherein: the disc assembly (25) comprises a movable disc (251) and a fixed disc (252), the movable disc (251) and the fixed disc (252) are arranged along the axial direction of the impeller (21), the movable disc (251) and the fixed disc (252) are sequentially arranged from a first bracket assembly (212) to a second bracket assembly (213), and the movable disc (251) is driven by a first shaft (222) to extend out of the fixed disc (252) and retract into the inner side of the fixed disc (252).

8. The range hood of claim 7, wherein: the movable tray body (251) is connected with the third connecting support (23), and the fixed tray body (252) is connected with the fourth connecting support (24).

9. The range hood according to any one of claims 1 to 8, wherein: on the flow path of the oil fume gas, the range hood further comprises a second fan (4) which is arranged at the downstream of the air inlet piece (1) and used for providing flow and negative pressure.

10. The range hood according to any one of claims 1 to 8, wherein: on the flow path of the oil fume gas, the range hood further comprises a filtering device (3) which is arranged at the downstream of the air inlet piece (1) and used for filtering the oil fume.

11. The range hood according to any one of claims 1 to 8, wherein: the air inlet piece (1) is also provided with a smoke concentration detection sensor (6) for detecting smoke concentration change so as to adjust the operation working condition of the first fan (2).

12. The range hood according to any one of claims 1 to 8, wherein: the air inlet piece (1) further comprises a guide plate (7) arranged on the radial inner side of the impeller (21).