MOTORIZED BASE FOR A FOOD PREPARATION DEVICE WITH LOW-NOISE VENTILATION

Description

Domaine technique

[0001] The invention relates to the field of motorized bases for food preparation appliances, particularly for domestic use.

[0002] Such motorized bases comprise an external housing having, on an upper side, a coupler configured to allow coupling and uncoupling of a work tool and to ensure the rotational drive of the work tool. The external housing comprises, on a lower side, a support base by which the motorized base is intended to rest on a receiving surface, for example a work surface. In this external housing of the motorized base, there is an electric motor having a motor shaft rotating around a motor axis, the motor having a first axial output which is connected to the coupler to ensure its rotational drive.

[0003] Such motorized bases are generally used as a base for a food preparation appliance that has a bowl, the bowl being removably attachable to the upper side of the motorized base, for example by a bayonet mechanism. The working tool is intended to be received in the bowl to interact with food introduced into the bowl. For this purpose, the bowl generally has a lower opening to allow coupling between the working tool and the coupler of the motorized base.

[0004] There are different categories of food preparation appliances that feature this design, although the layouts may differ between them.

[0005] For example, we know of devices commonly called “base robots”, a first type of which is illustrated in the form of a first example in document EP2074919, but also in the form of a second example in [ Fig.1 ] of the present application. Here the motorized base is generally parallelepipedal or cylindrical in shape, with an upper face which is the highest face of the motorized base, on which there is on the one hand a coupler for the work tool and on the other hand means for attaching a work bowl. In this case, the electric motor which drives the coupler is arranged below the upper face on which there is the coupler configured to allow the coupling and uncoupling of a work tool.

[0006] A second type of device is described in the form of a first example in document FR2934143 and in the form of a second example in [ Fig.2 ] of the present application. In this second type, the apparatus has a motorized base whose general shape is that of an L, with a lower portion of generally horizontal extension and a lateral portion of generally vertical extension relative to a lower face comprising the support base by which the motorized base is intended to rest on a receiving surface. In an apparatus of this second type, the lower portion of the motorized base comprises an upper face on which the coupler for the work tool is found, and on which the bowl is intended to be hung. The lower face of this lower portion comprises the support base by which the motorized base is intended to rest on a receiving surface.Laterally to this lower portion is the side portion which extends vertically higher than the upper face, to extend laterally beside the bowl when the latter is installed on the lower portion. In such an L-shaped embodiment, the electric motor may be arranged inside the side portion, and may therefore extend vertically higher than the upper face of the lower portion. In such a case, the electric motor may be installed vertically, with a lower end which is connected, for example by means of a belt extending in the lower portion, to the coupler intended to ensure the drive of the working tool.

[0007] In the context of motorized bases for such devices, the invention relates more particularly to the optimization of the cooling of the electric motor driving the work tool. Indeed, it is known to provide in such motorized bases a fan which is directly arranged at one end of the motor, for example by being mounted directly on an output end of the shaft of the electric motor. Generally, the fan is configured to suck in a flow of air along the electric motor, and to reject this flow of air towards the outside of the external housing, through an air outlet arranged in this external housing.

[0008] There are many suggestions for the arrangement of the ventilation device to ensure air circulation between the fan and the air outlet. Technique antérieure

[0009] Document CN 208 510 851 describes a device in which the fan is housed in a collector which communicates with an outlet chamber by a conduit in the shape of an arc around the collector. The collector, the conduit in the shape of an arc and the outlet chamber are substantially in the same plane. The outlet chamber has a lower wall which coincides with the lower face of the motorized base and which has vents through which the discharged air can exit towards the outside, downwards towards the receiving surface on which the motorized base rests. Document CN108078437A also describes a spiral chamber.

[0010] Document CN 208 339 432 describes a device in which the air discharged by the fan is engaged in a spiral chamber around the motor axis which is perpendicular to the lower face of the motorized base. This chamber also has, in its lower wall which coincides with the lower face of the motorized base, vents through which the discharged air can exit towards the outside, downwards towards the receiving surface on which the motorized base rests.

[0011] Document CN108324134A describes a device in which the air that is circulated by the fan inside the motorized base is drawn through an inlet and then conducted into a tubular suction chimney along the motor to an upper end of the latter, before descending along the motor into a cylindrical chamber delimited at the center of the tubular chimney. The cylindrical chamber and the tubular chimney are located upstream of the fan. Document CN108742190A describes another device in which the air is circulated by a fan.

[0012] It is understood that good ventilation of the motor is an important characteristic to ensure its reliability. Furthermore, it is also understood that the ventilation circuit can be a significant source of noise emission towards the outside of the motorized base. This noise can include the noise generated in itself by the electric motor and by the moving mechanical components located inside the external casing of the motorized base. This noise can also include aeraulic noises from the incoming and outgoing air flow. It is understood that the prior art has already sought solutions making it possible to find an optimal compromise between the requirement for ventilation efficiency, requiring the greatest possible air flow, the requirement for the lowest possible noise emission, and the ability of the ventilation circuit to be integrated into an external casing that remains compact. Exposé de l'invention

[0013] For this purpose, the invention proposes a motorized base for a food preparation appliance, of the type comprising: an external housing having, on an upper side, a coupler configured to allow coupling and uncoupling of a work tool and to ensure the rotational drive of the work tool, the external housing comprising, on a lower side, a support base by which the motorized base is intended to rest on a receiving surface, in the external housing, an electric motor having a motor shaft rotating about a motor axis, the electric motor having a first axial end and a second axial end, opposite the first axial end, which rotates a fan which is arranged on the side of the second axial end of the motor and which sucks in an air flow which circulates along the electric motor from the first axial end to the second axial end, the fan discharging an outgoing air flow which is channeled according to a downstream circuit towards an outlet orifice arranged in a face of the external housing,at which the outgoing air flow is ejected outside the external housing, the downstream circuit comprising, successively in the direction of circulation of the outgoing air flow, a collector, a transfer duct, and the outlet orifice.

[0014] The motorized base is characterized in that the downstream circuit comprises, between the transfer conduit and the outlet orifice, a double chimney having an upstream tubular outer channel, which extends in a chimney direction from an upstream end connected to the transfer conduit, and which is fluidically connected, by means of a return volume, to a downstream inner channel which extends inside the volume of the upstream tubular outer channel in the chimney direction to a downstream end which corresponds to the outlet orifice.

[0015] The invention may also include, in certain embodiments, one or more of the following optional features.

[0016] The outgoing air flow can travel through the double chimney first in the upstream tubular outer channel, in a first direction of the chimney direction, then in the downstream inner channel, in a second direction opposite to the first direction of the chimney direction.

[0017] The double chimney may comprise a tubular external partition which extends in the chimney direction and a tubular internal partition which extends in the chimney direction inside the volume delimited by the tubular external partition so that the two partitions delimit between them the upstream tubular external channel while the tubular internal partition delimits the downstream internal channel.

[0018] The transfer duct can extend in a direction perpendicular to the motor axis.

[0019] The transfer conduit may have an increasing cross-section going from the collector towards the upstream end of the upstream tubular outer channel.

[0020] The fan may be a centrifugal fan that discharges the airflow exiting the fan in a direction orthogonal to the motor axis. The transfer duct may then be oriented orthogonally to the motor axis.

[0021] The fan can be an axial fan which discharges the air flow exiting the fan in the axial direction of the motor axis.

[0022] The transfer duct can be oriented orthogonally to the motor axis. The collector can deflect the airflow exiting the fan in the axial direction of the motor axis towards the transfer duct.

[0023] The collector may have a wall perpendicular to the motor axis, arranged near the fan, on the side opposite the electric motor relative to the fan. The transfer duct may then have a side wall which extends the rear wall of the collector.

[0024] The chimney direction may extend in a direction perpendicular to a main direction of the transfer duct.

[0025] The transfer duct can guide the outgoing air flow so that it is injected into the upstream tubular outer channel of the double chimney in a direction tangential to the chimney direction.

[0026] The chimney direction can be parallel to the engine axis, and be offset transversely relative to the engine axis.

[0027] The double chimney can extend parallel next to the electric motor in the external housing.

[0028] The chimney direction can extend perpendicular to the engine axis.

[0029] The turnaround volume may be delimited by an end wall of the double chimney which is connected over an entire circumference to a downstream end of the tubular external partition of the double chimney. An upstream free edge of the tubular internal partition may then be arranged at a distance from the end wall of the double chimney to form the turnaround volume.

[0030] The double chimney may have a concave internal face and have a torus section shape having an axis parallel to the chimney direction, the torus section being cut by a plane perpendicular to the axis of the torus.

[0031] The downstream interior channel may have an increasing cross-section towards its downstream end according to the chimney direction.

[0032] The downstream interior channel may have a shape of revolution around an axis which forms the chimney direction.

[0033] The downstream end of the downstream inner channel which corresponds to the outlet orifice may have a flared geometry like the bell of a musical instrument.

[0034] The upstream tubular outer channel may have an increasing cross-section from its upstream end towards the turning volume according to the chimney direction.

[0035] The upstream tubular external channel may have a shape of revolution around an axis parallel to the chimney direction.

[0036] The upstream tubular outer channel and the downstream inner channel can be coaxial.

[0037] The cross-section of the downstream inner channel can always be greater than the cross-section of the upstream outer tubular channel. Thus, the air flow occurs through a continuously increasing cross-section.

[0038] The downstream circuit may have a cross-section increasing in the direction of circulation of the outgoing air flow from the inlet of the transfer duct to the outlet orifice.

[0039] The chimney direction can be vertical and the outlet can then be arranged in a lower face of the external casing.

[0040] The chimney direction can be inclined from the vertical and the outlet can then be arranged in a side face of the external housing.

[0041] The first axial end of the electric motor can be connected to the coupler to ensure its rotational drive.

[0042] The invention also provides a food preparation appliance comprising a motorized base and a working accessory arranged on the motorized base, the working accessory comprising a working container and a working tool arranged in the working container and driven in rotation by the motorized base, in which the motorized base conforms to at least one of the aforementioned characteristics. Brève description des dessins

[0043] [ Fig.1 ] There [ Fig.1 ] is a schematic front view of a first type of food preparation appliance in which the invention can be implemented. [ Fig.2 ] There [ Fig.2 ] is a schematic perspective view of a second type of food preparation appliance in which the invention can be implemented. [ Fig.3 ] There [ Fig.3 ] represents a perspective view with partial tearing, along the broken line III-III of the [ Fig.4 ], of a motorized base according to a first embodiment of the invention. [ Fig.4 ] There [ Fig.4 ] is a schematic sectional view of the motorized base according to the [ Fig.3 ], according to the broken line IV-IV of the [ Fig.5 ]. [ Fig.5 ] There [ Fig.5 ] is a schematic sectional view of the motorized base according to the [ Fig.3 ], according to the broken line III-III of the [ Fig.4 ]. [ Fig.6A-6C ] THE figures 6A-6C schematically illustrate a second embodiment of a motorized base according to the invention, respectively according to a first schematic view in vertical section 6A, according to a schematic view 6B in section through the plane VIB-VIB of the view 6A, and according to a schematic view in section 6C through the plane VIC-VIC of the view 6A. [ Fig.7A-7C ] THE figures 7A-7C schematically illustrate a third embodiment of a motorized base according to the invention, according to a schematic view 7B in section through plane VIIB-VIIB of view 7A, and according to a schematic view in section 7C through plane VIIC-VIIC of view 7A. [ Fig.8A-8C ] THE figures 8A-8C schematically illustrate a fourth embodiment of a motorized base according to the invention, respectively according to a first schematic view in section 8A, according to a schematic view 8B in section through plane VIIIB-VIIIB of view 8A, and according to a schematic view in section 8C through plane VIIIC-VIIIC of view 8A. [ Fig.9 ] There [ Fig.9 ] schematically illustrates in section a fifth embodiment of a motorized base according to the invention. [ Fig.10 ] There [ Fig.10 ] schematically illustrates in section an alternative embodiment of the double chimney, capable of being implemented in all the previous embodiments. Description des modes de réalisation

[0044] On the Figs. 1 et 2 , two examples of a culinary preparation appliance 10 for domestic use in which the invention can be implemented are shown, corresponding to two different types of appliance.

[0045] In both cases, such an appliance 10 essentially comprises a motorized base 12 as well as a working accessory 14 comprising a working container 15, sometimes called a bowl, and a working tool 16 which is intended to be received inside the working container 15 and which is intended to be driven in rotation inside the latter, by coupling with the motorized base 12, in order to interact with food introduced into the working container 15. Depending on the nature, geometry and rotational speed of the working tool 16, the working container 15 may be closed by a cover 17. Depending on the nature and geometry of the working container 15, and depending on the nature, geometry and rotational speed of the working tool 16, such an appliance 10 is sometimes called a “multifunction robot” or “blender”. In a known manner, the working container 15 is removably attached to the motorized base 12.

[0046] The motorized base 12 comprises an external housing 18 which can have any geometry. In the first type of device illustrated in [ Fig.1 ], it can be seen that the geometry of the external housing 18 is substantially that of a parallelepiped or a truncated pyramid. In the second type, an example of which is illustrated in [ Fig.2 ], the geometry of the external housing 18 is substantially that of an L, with a lower portion 18a of generally horizontal extension and a lateral portion 18b of generally vertical extension relative to a lower face 21 comprising the support base 24 by which the motorized base 12 is intended to rest on a receiving surface S, such as a work surface, not forming part of the device 10.

[0047] In any case, we can distinguish, for example on the [ Fig.3 ], a lower side 20 and an upper side 22. The lower side 20 is the one which has a support base 24 by which the motorized base 12 is intended to rest on the receiving surface. The upper side 22 of the external housing 18 is the one on which a coupler 26 can be found configured to allow coupling and uncoupling of the working tool 16 and to ensure the rotational drive of the working tool 16. The notions of “upper” and “lower” refer to the vertical direction of the Earth’s gravity, and refer to the orientation of the apparatus 10 during normal use. The coupler 26 can be any mechanism known in the field, and can for example comprise a splined shaft.

[0048] In the first type of device illustrated in [ Fig.1 ], in which the outer casing 18 has a single-volume geometry, for example in the shape of a parallelepiped, a cylinder or a truncated pyramid, the outer casing 18 thus has a lower face 21, which forms the lower side, and an upper face 23 which forms the upper side 22. In a configuration of use of the apparatus 10, the lower face 21 and the upper face 23 are oriented horizontally. The upper face 23 also comprises a mechanism for removable attachment of the working container 15 to the motorized base 12, for example a bayonet mechanism. The outer casing 18 comprises one or more lateral faces 28 which connect the lower face 21 to the upper face 23 and which are of mainly vertical extension in the configuration of use of the apparatus. The outer casing 18 is generally made in several parts, with for example a lower half-shell and an upper half-shell.

[0049] In a device 10 of the second type as illustrated in [ Fig.2 ], the lower portion 18a of the motorized base 12 comprises an upper face 23 on which the coupler 26 for the work tool 16 is located, and on which the work container 15 is intended to be hung. The lower face 21 of this lower portion 18a comprises the support base 24 by which the motorized base 12 is intended to rest on a receiving surface. Laterally with respect to this lower portion 18a, there is the lateral portion 18b which extends vertically higher than the upper face 23, to extend laterally next to the work container 15 when the latter is installed on the lower portion 18a.

[0050] The first embodiment illustrated on the Figs. 3 à 5 , as well as the second, third and fourth embodiments illustrated respectively in Fig. 6A-6C , to the Fig. 7A-7C , and to the Fig. 8A-C , are examples of motorized bases corresponding to the first type of device. The fifth embodiment illustrated in [ Fig.9 ] is an example of a motorized base corresponding to the second type of device.

[0051] In all cases, the external housing 18 of the motorized base 12 therefore delimits an internal space in which is received in particular a drive mechanism of the coupler 26. Thus, the motorized base 12 comprises, in the external housing 18, an electric motor 30 having a motor shaft 32 rotating about a motor axis A1. The electric motor 30 thus has a first axial end 34, and a second axial end 36, opposite the first axial end relative to the electric motor 30 in the direction of the motor shaft 30. In the examples, the first axial end 34 and the second axial end 36 are axial ends of the motor shaft 32 on either side of the electric motor 30 in the direction of the motor axis A1.

[0052] In an apparatus of the second type, in L, the electric motor 30 may be arranged inside the lateral portion 18b of the external housing 18, and may therefore, for example, extend vertically higher than the upper face 23 of the lower portion 18a. In such a case, the electric motor may be installed vertically, with a lower end which is connected, for example by means of a belt which extends in the lower portion, to the coupler 26 intended to ensure the driving of the working tool 14, as can be seen in the [ Fig.9 ].

[0053] The electric motor 30 rotates on the one hand the coupler 26 and on the other hand a fan 40 which is arranged on the side of an axial end of the electric motor 30, which will be arbitrarily called here the second axial end 36 of the motor. The fan 40, when it rotates around its axis, sucks in a flow of air which circulates along the electric motor 30 from the first axial end 34 to the second axial end 36. In the examples illustrated, it can be seen that the fan 40 is coaxial with the electric motor 30, therefore having as its axis of rotation the motor axis A1. It can thus be mounted directly on the second axial end 36 of the motor shaft 32 and thus be driven at the rotation speed of the motor shaft 32.However, it could be provided that the fan 40 is driven in rotation by the second axial end 36 of the motor shaft by means of a speed reducer or a speed multiplier, for example in the form of a gear mechanism.

[0054] In the first example illustrated on the Figs. 3 à 5 , the electric motor 30 is installed vertically, the motor axis A1 therefore being vertical, perpendicular to the lower face 21 which has the support base 24. It is the same in the second example of the Fig. 6A-6C , and in the fifth example of the [ Fig.9 ]. However, as illustrated in the third example of the Fig. 7A-7C or the fourth example of the Fig. 8A-8C , the invention can also be implemented in motorized bases in which the electric motor 30 is installed horizontally, or even installed in an oblique direction. In this case, an angle transmission mechanism 38, for example by bevel gears, is provided between the electric motor 30 and the coupler 26.

[0055] In certain embodiments, the coupler 26 is driven in rotation by the first axial end 34 of the electric motor 30, therefore by the axial end which is opposite to that where the fan 40 is arranged. However, as will be seen for the fifth embodiment of the [ Fig.9 ], the coupler 26 can be driven in rotation by the second axial end 36 of the electric motor 30, therefore by the same axial end as that where the fan 40 is arranged. The connection between the first axial end 34 or the second axial end 36 of the electric motor 30 and the coupler 26 can be direct, with for example the coupler 26 mounted directly on the axial end of the motor shaft 32 of the electric motor 30. However, the connection between the first axial end 34 or the second axial end 36 of the electric motor 30 and the coupler 26 can be indirect. Thus, the coupler 26 can be driven in rotation by the electric motor 30 via a mechanical transmission which can comprise a transmission belt 29, and / or a gear train, and / or a transmission hose.

[0056] In some embodiments, for example the first and second embodiments, the coupler 26 is coaxial with the motor shaft 32, and extends along the motor axis A1 of the electric motor 30. This is possible with a direct connection of the coupler 26 with the axial end 34, 36 of the electric motor 30, but also with an indirect connection. In the case of an indirect connection, the coupler 26 may not be coaxial with the motor shaft 32, as illustrated with the third, fourth and fifth embodiments which use a transmission belt 29.

[0057] In all embodiments, the fan 40 draws in an air flow which circulates along the electric motor in the direction of the motor axis A1, in a direction of circulation which goes from the first axial end 34 to the second axial end 36 of the electric motor 30. Advantageously, the motorized base may comprise a jacket 42, for example of cylindrical shape in the direction of the motor axis A1, which at least partly surrounds the electric motor 30 around the motor axis A1, preferably on the axial extension going from the first axial end 34 to the second axial end 36 of the electric motor 30, to channel the air flow drawn in by the fan 40 along the electric motor 30. Such a jacket 42 may be connected to an air inlet arranged in a face of the external housing 18, for example a lateral face 28 of the external housing 18.

[0058] The fan 40 discharges an outgoing air flow which, inside the external housing 18, is channeled according to a downstream circuit 44 towards an outlet orifice 46 arranged in a face of the external housing 18, at the level of which the outgoing air flow is ejected outside the external housing 18. In the first embodiment of the Figs. 3 à 5 , and in the fifth embodiment of the [ Fig.9 ], the outlet orifice 46 is arranged in the lower face 21 of the outer housing 18. In other embodiments, such as the second, third and fourth embodiments, the outlet orifice 46 is arranged in a side face 28 of the outer housing 18.

[0059] As can be seen in the various figures, the downstream circuit 44 comprises, successively in the direction of circulation of the outgoing air flow, a collector 48, a transfer duct 50, and the outlet orifice 46.

[0060] The downstream circuit 44 is formed in the interior space delimited by the external housing 18. The downstream circuit 44 is formed of walls which allow the air to be channeled. These walls may be walls of dedicated components, or comprise walls of other components of the motorized base 12, in particular for example wall elements of the external housing 18, and / or internal compartmentalization walls of the external housing 18. It will be noted that the purpose of the downstream circuit 44 is to channel the outgoing air flow, discharged by the fan 40, towards the outlet orifice 46. The downstream circuit 44 may be designed to be sealed relative to the rest of the interior space delimited by the external housing 18. However, it is understood that this is not an obligation. It is expected that a majority of the mass flow rate of the outgoing air flow generated by the fan 40 will be channeled by the downstream circuit 44 to the outlet orifice 46.At least certain portions of the downstream circuit 44 may have leaks, in particular towards the rest of the interior space delimited by the external housing 18. Similarly, a part of the outgoing air flow, discharged by the fan 40, may be diverted, for example by an auxiliary circuit, towards other members to be ventilated of the motorized base 12.

[0061] Thus, the collector 48 of the downstream circuit 44 can advantageously comprise one or more walls whose shape and arrangement make it possible to collect and direct the air discharged by the fan 40 towards the transfer duct 50. The shape and arrangement of the collector 48 depend in particular on the shape of the fan 40, the type of fan 40, and the relative position and orientation of the transfer duct 50 with respect to the fan 40.

[0062] In the illustrated examples, the fan 40 is a centrifugal fan which discharges the air flow leaving the fan 40 in a direction orthogonal to the axis of rotation of the fan 40, here the motor axis A1. In the illustrated examples, the transfer duct 50 is oriented orthogonally relative to the motor axis A1, and substantially in the plane of rotation of the fan. As a result, the collector 48 essentially comprises a transverse rear wall 52 perpendicular to the motor axis A1, arranged opposite the fan 40, close to it, and on the opposite side of the electric motor 30 relative to the fan 40, and a crown 54 which extends in an arc of a circle around the motor axis A1 and around the fan 40, with the exception of an interruption which belongs to the junction between the collector 48 and the transfer duct 50.The transverse rear wall 52 may coincide with an external wall of the external housing 18, for example the lower wall 21 or a side face 28. The use of a centrifugal type fan makes it possible in particular to reduce the size, in the direction of the motor axis A1, of the assembly constituted by the electric motor 30, the fan 40 and the collector 48, so as not to have to increase the dimension of the motorized base according to this dimension. However, it would be very possible to have a fan which is an axial type fan which rejects the air flow leaving the fan in the axial direction of the motor axis A1.

[0063] The role, advantage and arrangement of the transfer conduit 50 will be detailed later.

[0064] The downstream circuit 44 comprises, between the transfer conduit 50 and the outlet orifice 46, a double chimney 56 having an upstream tubular outer channel 58, which extends in a chimney direction A2 from an upstream end 59 connected to the transfer conduit 50, and which is fluidically connected, by means of a turnover volume 60, to a downstream inner channel 62 which extends inside the upstream tubular outer channel 58 in the chimney direction A2 to a downstream end which corresponds to the outlet orifice 46. The double chimney 56 is received in the interior space delimited by the external housing 18. In certain embodiments, the upstream tubular outer channel 58 and the downstream inner channel 62 are coaxial.Preferably, the cross-section of the downstream inner channel 62 is always greater than the cross-section of the upstream tubular outer channel 58, so that the air flows through a continuously increasing cross-section.

[0065] A more detailed geometry of a first example of the realization of a double chimney 56 is visible in the Figs. 3 à 5 . A more detailed geometry of another example of the realization of a double chimney 56 is visible at [ Fig.10 ].

[0066] In any case, by design, the outgoing air flow that is generated by the fan 40 travels through the double chimney 56 first in the upstream tubular outer channel 58, in a first direction of the chimney direction A2, then in the downstream inner channel 62, in a second direction opposite to the first direction of the chimney direction 62. In other words, the double chimney 56 forms a baffle in the path that is available for the outgoing air flow. This baffle effect is particularly interesting in that it imposes a strong damping on the sound waves that are likely to propagate in the air along the downstream circuit 44. In particular, the sound waves that are generated by the interaction of the fan 40 with the outgoing air flow are damped by the baffle effect due to the presence of the double chimney 56.The double chimney 56 is arranged such that the upstream end 59 of the upstream tubular outer channel 58, through which the air flow enters the double chimney 56, cannot be located opposite the outlet orifice 46, thus preventing direct outward propagation of the sound waves propagated in the outgoing air flow.

[0067] In terms of construction, the double chimney 56 comprises a tubular external partition 64 which extends in the chimney direction A2 and which delimits radially outwards the upstream tubular external channel 58. The double chimney 56 also comprises a tubular internal partition 66 which also extends in the chimney direction A2, inside the volume delimited by the tubular external partition 64, so that the two partitions delimit between them the upstream tubular external channel 58 while the tubular internal partition 66 delimits the downstream internal channel 62. The tubular internal partition 66 and the tubular external partition 64 each have a length in the chimney direction A2, and the tubular internal partition 66 is nested over all or part of its length inside the volume delimited by the tubular internal partition 66.

[0068] Advantageously, it is possible to provide that the downstream internal channel 62 has a shape of revolution around an axis which forms the chimney direction A2. Similarly, it is possible to provide that the upstream tubular external channel has a shape of revolution around an axis parallel to the chimney direction A2, or even of revolution around the axis which forms the chimney direction A2.

[0069] Thus, in the illustrated examples, both the tubular external partition 64 and the tubular internal partition 66 have a geometry of revolution around an axis having as its direction the chimney direction A2. In this example, the tubular external partition 64 and the tubular internal partition 66 have a geometry of revolution around the same axis A2. However, it could be provided that the tubular external partition 64 and the tubular internal partition 66 have a geometry of revolution around two non-merged axes, for example two parallel axes offset transversely from each other. It can be provided that the tubular external partition 64 and the tubular internal partition 66 have a geometry of revolution around two axes that are not strictly parallel. Such non-parallel axes will preferably form a small angle between them, preferably less than 15 degrees of angle.

[0070] Preferably, as illustrated in the various examples, the tubular external partition 64 and the tubular internal partition 66 are entirely separate from each other. This makes it possible in particular to isolate them from each other in terms of vibrations, which can contribute to a reduction in the noise transmitted to the outside by the motorized base. However, in the case where the tubular external partition 64 and the tubular internal partition 66 have an elongated geometry around two non-merged axes, it can be provided that the two partitions are tangent to each other over all or part of their length (for curved geometries in section), or have a common face (for prismatic geometries in section).

[0071] In some illustrated examples, such as those of the second, third or fourth embodiment, one and / or the other of the tubular external partition 64 and the tubular internal partition 66 may have a cylindrical shape formed by the surface generated by a straight line following a closed contour while remaining parallel to itself. However, one and / or the other of the tubular external partition 64 and the tubular internal partition 66 may have a frustoconical shape. Thus, in the examples of the [ Fig.5 ] and the [ Fig.10 ], the tubular external partition 64 is substantially cylindrical while the tubular internal partition 66 has a truncated cone shape that flares downstream, both on its internal face and on its external face.

[0072] In the example illustrated on the Figs. 3 à 5 and in that of the [ Fig.10 ], the turning volume 60 is delimited by an end wall 68 of the double chimney 56 which is connected over an entire circumference of a downstream end of the tubular external partition 64 of the double chimney 56. Thus, the tubular external partition 64 delimits a volume which is blocked in the chimney direction A2 at its end opposite its upstream end. Furthermore, the tubular internal partition 66, which is received over at least part of its length in this volume, has an upstream free edge 70 which is arranged at a distance from the end wall 68 of the double chimney 56 to form the turning volume, this in order to provide a passage for the outgoing air flow between the upstream tubular external channel 58 and the downstream internal channel 62, this passage corresponding to the turning volume 60.

[0073] In the example illustrated on the Figs. 3 à 5 and in that of the [ Fig.10 ], the end wall 68 of the double chimney 56 has a concave internal face and has a torus section shape having an axis parallel to the chimney direction A2, or even, in the example, coincident with the axis of symmetry of revolution of the double chimney 56, the torus section being cut by a plane perpendicular to the axis of the torus. This geometry is favorable for the reversal of the outgoing air flow whose general direction of flow makes a 180° reversal between the upstream tubular external channel 58 and the downstream internal channel 62.

[0074] As can be seen more particularly for the first example illustrated on the Figs. 3 à 5 and for that of the [ Fig.10 ], the downstream inner channel 62 may have an increasing cross-section going towards its downstream end in the chimney direction A2. This is particularly interesting insofar as it makes it possible to slow down the flow rate of the outgoing air flow at the outlet orifice 46, which reduces the level of aeraulic noise due to the flow of the outgoing air flow. This can be obtained in particular with a truncated tubular inner partition 66, or in any case flared. Similarly, it can be provided that the upstream tubular outer channel 58 has an increasing cross-section going in the chimney direction from its upstream end towards the turning volume, as in the first example illustrated in the Figs. 3 à 5 , which here also promotes the reduction of the aeraulic noise level. Indeed, in this last example, the truncated nature of the external face of the tubular internal partition 66 makes it possible to obtain an increasing cross-section for the upstream tubular external channel 58, this despite the cylindrical nature of the internal face of the tubular external partition 64.

[0075] A reduction in the level of aeraulic noise due to the flow of the outgoing air flow can also be advantageously obtained by providing, as can be seen in the example illustrated on the [ Fig.10 ], that the downstream end of the downstream inner channel 62 which corresponds to the outlet orifice 46 has a flared geometry like the bell of a musical instrument, for example like a trumpet bell. This geometry further reduces the flow speed of the outgoing air flow and makes it possible to limit turbulence.

[0076] In the illustrated examples, it is noted that the chimney direction of the double chimney 56 can be represented in the form of a straight line A2. However, it could be provided that the chimney direction is slightly curved, while retaining the principle of having an upstream tubular outer channel, and a downstream inner channel which extends inside the volume of the upstream tubular outer channel in the chimney direction A2 to a downstream end which corresponds to the outlet orifice 46.

[0077] In the illustrated examples, it is noted that the chimney direction A2 of the double chimney 56 is perpendicular to the lateral face 28 or to the lower face 21 of the external housing 18 in which the outlet orifice 46 is formed. However, it could be provided that the chimney direction A2 of the double chimney 56 forms an angle of less than 90° with respect to the lateral face 28 or to the lower face 21 of the external housing 18 in which the outlet orifice 46 is formed. In other words, the downstream internal channel 62 may be oblique with respect to the lateral face 28 or to the lower face 21 of the external housing 18 in which the outlet orifice 46 is formed, for example by forming an angle of between 30 degrees of angle and 80 degrees of angle, with respect to the lateral face 28 or to the lower face 21 of the external housing 18 in which the outlet orifice 46 is formed.

[0078] In the first example illustrated on the Figs. 3 à 5 , the chimney direction A2 is parallel to the motor axis A1, and is offset transversely relative to the motor axis A1. The same configuration is found for the third and fifth embodiments. As will be detailed later, the transverse offset is notably permitted by the presence of the transfer duct 50. More precisely, in these examples, it is noted that the double chimney 56 extends at least partly at the height of the electric motor 30 in the direction of the motor axis A1, and in parallel with it in the external housing 18. This arrangement, in which the double chimney 56 is offset transversely but at least partly in parallel next to the electric motor 30 makes it possible to reduce the dimension, in the direction of the motor axis A1, of the assembly constituted by the electric motor 30 and the double chimney 56.

[0079] Alternatively, in some embodiments, such as the second and fourth exemplary embodiments of the Fig. 6A-6C and of the Fig. 8A-8C , the chimney direction A2 extends perpendicular to the motor axis A1.

[0080] Thus, it is understood that, whatever the vertical or horizontal orientation of the motor axis A1, the chimney axis can be oriented horizontally, to have an outlet orifice 46 in a lateral face 28 of the external housing 18 (which can be favorable to a limitation of the resistance to the circulation of the outgoing air flow, therefore favorable to the efficiency of the ventilation), or in the lower face 21 of the external housing 18 (which can be favorable to a reduction of the noise, and to a limitation of the risk of unwanted entry of material into the downstream circuit 44 via the outlet orifice 46). Thus, in the first, fourth and fifth embodiments, the chimney direction A2 is vertical and the outlet orifice is arranged in a lower face of the external housing 18, while in the second and third embodiments, the chimney direction A2 is horizontal and the outlet orifice 46 is arranged in a lateral face 28 of the external housing 18.

[0081] In all cases, the transfer duct 50 extends between the fan 40 and the upstream tubular outer channel 58. Of course, in the case of a particularly compact construction, the length of the transfer duct 50 may be short, or may even be in the form of a simple transfer window between the collector 48 and the upstream tubular outer channel 58. When the fan 40 is a centrifugal fan, the transfer duct preferably extends in a direction perpendicular to the motor axis A1. It is noted that, in this case, the transfer duct may advantageously have a side wall which extends the transverse rear wall 52 of the collector 48, this to limit the generation of aerodynamic turbulence, which is favorable to an increase in ventilation efficiency and a reduction in aeraulic noise.In the case of an axial fan, it will be advantageous to provide that the geometry of the collector diverts the air flow leaving the fan towards the transfer duct 50, which is therefore discharged by the fan in the axial direction of the fan.

[0082] Preferably, the transfer duct 50 has an increasing cross-section going from the collector 48 towards the upstream end of the upstream tubular outer channel 58, in order to reduce the level of turbulence of the outgoing air flow.

[0083] Preferably, the downstream circuit 44 has a cross-section that increases in the direction of circulation of the air flow exiting from the inlet of the transfer duct 50 to the outlet orifice 46.

[0084] Preferably, the chimney direction A2 extends in a direction perpendicular to a main direction of the transfer duct. More precisely, it may advantageously be provided that the transfer duct 50 guides the outgoing air flow such that it is injected into the upstream tubular outer channel 58 of the double chimney 56 in a direction tangential to the chimney direction. With such a configuration, the flow of the outgoing air flow is facilitated at the upstream end of the upstream tubular outer channel 58, therefore during the passage from the transfer duct 50 to the double chimney 56. This configuration in particular promotes a helical flow of the outgoing air flow, at least in an upstream portion of the upstream tubular outer channel 58, again for the benefit of less loss of aeraulic energy, which promotes the efficiency of the ventilation.

Claims

1. Motorised base (12) for a food preparation appliance (10), said motorised base (12) comprising: - an outer casing (18) having, on an upper side (22), a coupler (26) configured to enable a coupling and an uncoupling of a work tool (16) and to ensure the rotation of the work tool (16), the outer housing (18) comprising, on a lower side (20), a support underframe (24) by which the motorised base (12) is intended to rest on an accommodating surface (S), - in the outer housing (18), an electric motor (30) having a motor shaft (32) rotating about a motor axis (A1), the electric motor (30) having a first axial end (34) and a second axial end (36), opposite the first axial end (34), which rotates a fan (40) which is arranged on the side of the second axial end (36) of the motor and which suctions a flow of air which circulates along the electric motor (30) from the first axial end (34) to the second axial end (36), the fan (40) discharging an outgoing flow of air which is channeled along a downstream circuit (44) to an outlet opening (46) arranged in a face of the outer casing (18), at the level of which the outgoing flow of air is ejected outside of the outer housing (18), the downstream circuit (44) comprising, successively in the direction of circulation of the outgoing flow of air, a collector (48), a transfer duct (50), and the outlet opening (46), characterised in that the downstream circuit (44) comprises, between the transfer duct (50) and the outlet opening (46), a double vent (56) having an upstream tubular outer channel (58), which extends in a venting direction (A2) from an upstream end (59) connected to the transfer duct (50), and which is fluidically connected, via a turnaround volume (60), to a downstream inner channel (62) which extends inside of the volume of the upstream tubular outer channel (58) in the venting direction (A2) as far as a downstream end which corresponds to the outlet opening (46).

2. Motorised base (12) according to claim 1, characterised in that the outgoing flow of air crosses the double vent (56) first in the upstream tubular outer channel (58), in a first direction of the venting direction (A2), then in the downstream inner channel (62), in a second direction opposite the first direction of the venting direction (A2).

3. Motorised base (12) according to any one of claims 1 or 2, characterised in that the double vent (56) comprises a tubular outer partition (64) which extends in the venting direction (A2) and a tubular inner partition (66) which extends in the venting direction (A2) inside the volume delimited by the tubular outer partition (64), such that the tubular outer partition (64) and the tubular inner partition (66) delimit, between them, the upstream tubular outer channel (58) while the tubular inner partition (66) delimits the downstream inner channel (62).

4. Motorised base (12) according to any one of claims 1 to 3, characterised in that the transfer duct (50) has an increasing transverse cross-section by going from the collector (48) to the upstream end (59) of the upstream tubular outer channel (58).

5. Motorised base (12) according to any one of claims 1 to 4, characterised in that the fan (40) is a centrifugal fan which discharges the outgoing flow of air of the fan in a direction orthogonal to the motor axis (A1) and in that the transfer duct (50) is oriented orthogonally with respect to the motor axis (A1).

6. Motorised base (12) according to any one of claims 1 to 4, characterised in that the fan (40) is an axial fan which discharges the outgoing flow of air of the fan in the axial direction of the motor axis (A1).

7. Motorised base (12) according to claim 6, characterised in that the transfer duct (50) is oriented orthogonally with respect to the motor axis (A1), and in that the collector (48) diverts the outgoing flow of air from the fan (40) in the axial direction of the motor axis (A1) to the transfer duct (50).

8. Motorised base (12) according to any one of claims 1 to 7, characterised in that the venting direction (A2) extends in a direction perpendicular to a main direction of the transfer duct (50).

9. Motorised base (12) according to any one of claims 1 to 8, characterised in that the transfer duct (50) guides the outgoing flow of air such that it is injected into the upstream tubular outer channel (58) of the double vent (56) in a tangential direction with respect to the venting direction (A2).

10. Motorised base (12) according to any one of claims 1 to 9, characterised in that the venting direction (A2) is parallel to the motor axis (A1), and is transversally offset with respect to the motor axis (A1).

11. Motorised base (12) according to any one of claims 1 to 9, characterised in that the venting direction (A2) extends perpendicularly to the motor axis (A1).

12. Motorised base (12) according to any one of claims 1, 2, 4 to 11 combined with claim 3, characterised in that the turnaround volume (60) is delimited by an end wall (68) of the double vent (56) which is connected over an entire circumference of a downstream end of the tubular outer partition (64) of the double vent (56), and in that an upstream free edge (70) of the tubular inner partition (66) is arranged at a distance from the end wall (68) of the double vent (56) to form the turnaround volume (60).

13. Motorised base (12) according to claim 12, characterised in that the end wall (68) of the double vent (56) has a concave inner face and has a toroidal cross-sectional shape having an axis parallel to the venting direction (A2), the toroidal cross-section being cut by a plane perpendicular to the toroidal axis.

14. Motorised base (12) according to any one of claims 1 to 13, characterised in that the downstream inner channel (62) has an increasing transverse cross-section by going to its downstream end in the venting direction (A2).

15. Motorised base (12) according to any one of claims 1 to 14, characterised in that the downstream end of the downstream inner channel (62) which corresponds to the outlet opening (46) has a bell-shaped flared geometry.

16. Motorised base (12) according to any one of claims 1 to 15, characterised in that the upstream tubular outer channel (62) has an increasing transverse cross-section by going from its upstream end (59) to the turnaround volume in the venting direction (A2).

17. Motorised base (12) according to any one of claims 1 to 16, characterised in that the transverse cross-section of the downstream inner channel (62) is always greater than the transverse cross-section of the upstream tubular outer channel (58).

18. Motorised base (12) according to any one of claims 1 to 17, characterised in that the venting direction (A2) is vertical and in that the outlet opening (46) is arranged in a lower face (21) of the outer housing (18).

19. Motorised base (12) according to any one of claims 1 to 18, characterised in that the first axial end (34) of the electric motor (30) is connected to the coupler (26) to ensure its rotation.

20. Food preparation appliance (10) comprising a motorised base (12) and a work accessory (14) arranged on the motorised base (12), the work accessory (14) comprising a work container (15) and a work tool (16) arranged in the work container (15) and rotated by the motorised base (12), characterised in that the motorised base is according to any one of claims 1 to 19.