Kitchen appliance provided with a reinforced electric motor-gear stage arrangement and method for producing an electric motor-driven kitchen appliance

An electric motor-driven kitchen appliance includes an electric motor having a motor housing and a gear stage having a gear case fastened to the electric motor. A removable reinforcement frame is around the motor housing and gear case. The electric motor-gear stage arrangement can be tested outside of the housing of the kitchen appliance and produced in a cost effective manner, being particularly torsionally rigid due to the removable reinforcement frame, thereby exhibiting an operation reliability.

The invention relates to an electric motor-driven kitchen appliance, particularly a single or multipurpose electric motor-driven kitchen appliance, provided with an insertable electric motor-gear stage arrangement comprising an electric motor having a motor housing, and a gear stage having a gear casing fastened to said electric motor; the invention further relates to a method for producing an electric motor-driven kitchen appliance.

BACKGROUND OF THE INVENTION

Known from document DE 25 51 842 is a multipurpose kitchen appliance having a plurality of holders for attachments, such as a dough hook, meat grinder or the like, which are driven at different rotational speeds. At least one gear stage is required for this purpose, to enable the rotational speed provided by the electric motor to be adapted to the speed required by each tool.

DE 39 32 760 A1 discloses a frame for electric motors for driving domestic appliances such as mixers, electric knives and the like, having two lateral supports interconnected at the front end by bridging pieces. These bridging pieces support the motor shaft, and it is also possible for one of the two bridging pieces to support the drive system. The motor frame is formed from two interconnected half shells having a cutout in their central area to allow a stator, a rotor with collector and a fan wheel to pass through, as well as support points for the motor shaft and drive system.

SUMMARY OF THE INVENTION

The object of this invention is to provide an electric motor-driven kitchen appliance and a method for producing such a kitchen appliance whereby the item can be assembled more easily and its production can be designed to be more cost-effective.

This object is inventively achieved by the electric motor-driven kitchen appliance and by the method for producing a kitchen appliance as described herein with respect to the exemplary embodiments. Further advantageous embodiments and developments of the invention, which can be applied individually or in any combination with one another, will emerge from the respective exemplary embodiments described herein.

The electric motor-driven kitchen appliance to which the invention relates, in particular the single or multipurpose kitchen appliance, provided with an insertable electric motor-gear stage arrangement comprising an electric motor having a motor housing and a gear stage having a gear case fastened to said electric motor, comprises a preferably removable reinforcement frame arranged around the motor housing and gear casing.

The electric motor and gear stage are preassembled into an electric motor-gear stage arrangement. The electric motor-gear stage arrangement can thus be tested and rated separately from the electric motor-driven kitchen appliance, in particular while separate from the housing of said electric motor-driven kitchen appliance. This makes it possible to find out in advance whether there are any deficiencies in the electric motor or the gear stage or the arrangement of the electric motor and the gear stage. For example, noise measurement can be used on the electric motor-gear stage arrangement to determine whether said electric motor-gear stage arrangement, that is, the central functional component of the electric motor-driven kitchen appliance, is operating perfectly. The electric motor-gear stage arrangement is strengthened with the aid of the removable reinforcement frame. This is particularly advantageous since it provides reinforcement against torsion along an axis of the motor. Both the motor housing and the gear casing can then be designed more simply.

For example the motor housing or the gear casing is produced using fiber-reinforced plastic. The removable reinforcement frame is advantageously made of metal.

In particular the reinforcement frame forms a connection which is in the main torsionally rigid along the connecting line between the electric motor and the gear stage, it being in particular possible for the torsionally rigid connection to withstand torque values within the range 3 Newtonmeter to 100 Newtonmeter, and preferably within the range 5 Newtonmeter to 50 Newtonmeter, though the particularly preferred range is from 10 Newtonmeter to 20 Newtonmeter.

In particular the reinforcement frame can be produced from metal, in particular by punching, pressing or die-casting. Manufacturing processes of this kind can produce particularly torsionally rigid structures.

The reinforcement frame is screwed to the gear casing and/or motor housing in particular fewer than ten screws, but in particular fewer than six screws, and preferably only one screw.

The gear casing and motor housing or the reinforcement frame can have connection elements, in particular connection projections, preferably an annular spring, and connection counter elements, in particular connection receivers, preferably an annular groove, providing a thread-free means of fastening the reinforcement frame to the gear casing or motor housing. Thread-free fastenings for the reinforcement frame have the advantage that in the main said reinforcement frame need only be slipped over the electric motor-gear stage arrangement, thereby greatly simplifying the cost and effort of assembly.

The reinforcement frame advantageously has a U-shaped or L-shaped metal section. A profile of this kind enables the reinforcement frame to be made relatively light while being capable of withstanding high torque values. In practice a particularly light embodiment of the electric motor-gear stage arrangement is advantageous in order to make the kitchen appliance easy to handle.

In a particular embodiment an attachment, in particular a puree blender, mixer, shredder, kneader and/or cutter, a crusher or beater, a drinks mixer, a slicer, a flour sifter, a juicer and/or a meat grinder can be connected to the kitchen appliance. For this purpose the kitchen appliance has in particular a plurality of attachment holders that can be operated at different revolution frequencies depending on the attachment concerned. The plurality of attachments enables the kitchen appliance to be versatile in use.

The motor housing and/or gear casing in particular are made from plastic, and in particular from glass fiber or carbon fiber reinforced plastic. The reinforcement frame enables both the motor housing and the gear casing to be simply and cost-effectively produced, since mechanical stability is not provided by the motor housing or gear casing as such, but rather, they must first be connected with the reinforcement frame.

The gear casing and motor housing in particular are connected together by means of a bolt flange, in particular by means of a bayonet lock. A bayonet lock greatly simplifies assembly of the electric motor with the gear stage and enables the kitchen appliance to be produced more cost-effectively.

The inventive method is for producing a kitchen appliance, in particular the inventive kitchen appliance, provided with a housing that has an electric motor fitted with a motor housing and a gear stage fitted with a gear casing, wherein the motor housing is connected to the gear casing, for the purpose of preassembling an electric motor-gear stage arrangement, in such a way that a motor shaft of the electric motor is coupled to a drive shaft of the gear stage in a torsionally rigid manner, and a reinforcement frame is placed around the gear casing and motor housing so that the gear casing is connected to the motor housing in a torsionally rigid manner; and wherein the preassembled electric motor-gear stage arrangement is then installed in the appliance housing.

The electric motor-gear stage arrangement is considerably strengthened and stabilized by the use of a reinforcement frame. The electric motor-gear stage arrangement can be preassembled and then tested and rated outside of the kitchen appliance housing. This enables the assembly and production of the kitchen appliance to be considerably simplified.

The reinforcement frame is fastened to the motor housing and/or gear casing using in particular fewer than ten screws, but in particular fewer than six screws, and preferably only one screw. The reinforcement frame can also be clipped to the motor housing and/or gear casing. The use of clips can enable the respective components to be firmly fastened in a very quick and easy way. The electric motor-gear stage arrangement is advantageously tested and rated prior to installation in the appliance housing.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

FIG. 1shows an oblique perspective view of an inventive kitchen appliance1seen from the side and from above together with a housing2for said appliance and four different holders70for an attachment29, which can be embodied in the form of a beater74. In this case three of the four holders70can be driven by the electric motor3(seeFIG. 2 to 6).

FIG. 2is an oblique perspective view showing an electric motor-gear stage arrangement31of the inventive kitchen appliance1during preassembly, wherein a gear stage33is connected to the electric motor3by connecting together a gear casing32and a motor housing4with the aid of a bayonet lock34, whereby the gear casing32is rotated through an angle, placed on the motor housing4and fastened in place by being rotated in a direction of rotation47. The bayonet lock34enables the gear stage33to be simply but reliably connected to the electric motor3by rotating said gear stage and moving it a short distance.

FIG. 3shows an oblique perspective view of the electric motor-gear stage arrangement31as shown inFIG. 2, wherein the gear stage33is fastened to the electric motor3with the aid of the bayonet lock34by engaging a first bayonet lock part35on the electric motor3in a correspondingly matching second bayonet lock part embodied on the gear stage33.

FIG. 4shows an oblique perspective view of a further electric motor-gear stage arrangement31of the inventive kitchen appliance1in the state immediately before preassembly, wherein the electric motor3and the gear stage33are moved together along a connecting line38, when a gearing worm27of the electric motor3penetrates the interior of the gear stage33, it being possible by rotation of the gear stage33relative to the electric motor about the connection line38to engage the first bayonet lock part35on the electric motor3in the second bayonet lock part36on the gear stage33.

FIG. 5shows an electric motor-gear stage arrangement31of the inventive kitchen appliance1before assembly. To lock the bayonet lock34, the gear casing32is rotated through a locking angle46of 30° relative to the motor housing4, so that the first bayonet lock parts35located on the motor housing4engage with the second bayonet lock parts36located on the gear casing32. Located on a motor shaft20is a gearing element23embodied as a first cylindrical crossed helical gear wheel51, which rotates in the direction of rotation47when the electric motor3is operating, so that the rotation of the motor shaft20keeps the bayonet lock34locked during operation. The gear casing32or the motor housing4has connection counter elements42which are embodied in the form of connection receivers43to receive a reinforcement frame37(seeFIG. 6) having corresponding connection projections41. The reinforcement frame37also stabilizes the gear casing32relative to the motor housing4.

FIG. 6shows an oblique perspective view of the electric motor-gear stage arrangement31seen inFIG. 5, in its preassembled state, wherein the reinforcement frame37also reinforces the gear stage33and the electric motor3against torsion relative to one another. The reinforcement frame37is screwed to the motor housing4and/or to the gear casing32with the aid of screws39. The reinforcement frame37, which has an L-shaped profile, is fixed to the motor housing4or to the gear casing32with the aid of connection receivers43. The reinforcement frame37is embodied with an L-shaped metal section. The rotation of the motor shaft20of the electric motor3about the motor's axis of rotation5operates in the closing direction of the bayonet lock34, so that the gear stage33cannot work loose from the electric motor3even under heavy load. The gear stage33has a holder70which can accept an attachment29such as a beater74.

FIG. 7shows an oblique perspective view of the reinforcement frame37inFIG. 6. The reinforcement frame37is embodied as an L-shaped metal section44with corresponding connection elements40and connection projections41enabling it to be fastened to the gear casing32or to the motor housing4, for which purpose only a few screws39are needed. The reinforcement frame enables torque values of some 20 Nm to be accepted from the electric motor3. This approach produces a particularly rigid design which enables the electric motor-gear stage arrangement31to be preassembled so that the electric motor-gear stage arrangement31can be tested and rated prior to installation in a housing2of the kitchen appliance1.

FIG. 8shows a longitudinal section with perpendicular intersecting plane, through the electric motor-gear stage arrangement31. The electric motor3comprises the motor housing4in which are arranged a stator9having a corresponding stator coil10and a rotor6, which is free to move within said housing, having a corresponding rotor coil7. Located on the motor shaft20is a cooling wheel24, embodied as a fan wheel8. The dimensioning of the cooling wheel24, in particular the strength of the material used and the thermal properties of the material used, enables the heat developed in the rotor coil7or in the gear stage33to be dissipated by heat conduction. Connected to the motor shaft20in a torsionally rigid manner is a gearing element23which, in the form of a first bevel gear23, and together with a second bevel gear64of the gear stage33, forms a helical-bevel gearbox65. The second bevel gear64is used to start the rotation of a sun gear49of a planetary gear set54, which for its part is engaged with three planet wheels55which for their part run on a ring gear49. The rotation of the motor shaft20rotates the planet wheels55not only about their respective planet wheel axes56but also about a sun gear axis50, so that an attachment29plugged into a holder70of the planet wheel55executes a rotary motion on a cone. The sun gear axis50is perpendicular to the motor's axis of rotation5. The drive shafts77of the helical-bevel gearbox65are largely perpendicular to one another. The motor's axis of rotation5is then largely coplanar on a level with the sun gear axis50. The angle W1defined by the planet wheel axis56and the sun gear axis50is around 30°.

FIG. 9shows an electric motor-gear stage arrangement31of the inventive kitchen appliance1as a longitudinal section with a horizontal intersecting plane, and shows a gear stage33having a worm gear pair30and a parallel shaft gearbox58. Located on the motor shaft9in a torsionally rigid manner is a gearing worm27that engages with a worm gear28which is connected in a torsionally rigid manner to a first spur wheel59. Arranged opposite the worm gear by reference to the gearing worm27is a mating gear66, which is engaged with the gearing worm27and absorbs counter-forces. The first spur wheel59is engaged with a second spur wheel60, which is connected in a torsionally rigid manner via a sun gear shaft53to the sun gear49. Whereas the worm gear pair has a gear ratio of around 1:1, a gear reduction of 4:1 is obtained with the parallel shaft gearbox58. The length L3is between 80 and 100 mm. The length L4is between 90 and 120 mm. The cooling wheel6enables heat generated in the gearing worm27to be dissipated by heat conduction, while the heat generated inside of the motor shaft20is dissipated to the cooling wheel24. The cooling wheel has a wide seat and a considerable thickness D1in order to keep the heat transfer resistance and heat conduction resistance as low as possible. Additional cooling of the worm gear pair30then becomes superfluous. The cooling wheel24also has fan blades18which give support to the cooling process.

FIG. 10shows an electric motor-gear stage arrangement31of the inventive kitchen appliance, having a parallel shaft gearbox58and a cylindrical crossed helical gear48as the gear stage33, wherein the cylindrical crossed helical gear48has a first cylindrical crossed helical gear wheel51, which is fastened on the motor shaft20, and a second cylindrical crossed helical gear wheel52, which is connected in a torsionally rigid manner to a first spur wheel59. The first spur wheel59is engaged with a second spur wheel60, which is fastened on a second spur wheel shaft62and connected in a torsionally rigid manner to the sun gear49. The second spur wheel shaft62is largely parallel to a first spur wheel shaft61of the first spur wheel59. The second spur wheel shaft62has a holder70for an attachment29. A casing cover79has to be lifted in order to insert said attachment into the holder70. The parallel shaft gearbox58and the cylindrical crossed helical gear48form a connection that transmits the rotation for the planetary gear set54, which has the sun gear49, three planet wheels55and a ring gear69. The sun gear49, the planet wheels55and the ring gear69are conical in shape, so that when the motor shaft20rotates, an attachment29, inserted in a holder70on the planet wheels55, rotates about a planet wheel axis56which for its part rotates on a cone about a sun gear axis50. Due to the cone shape of the sun gear49, the planet wheels55and the ring gear69, the attachment29executes a wobbling movement, wherein the wobbling movement runs off-center on a cone with an apex angle of around 60°. The attachment29can be plugged into the holder70of a planet wheel55and be retained with the aid of an attachment holder81. The cylindrical crossed helical gear48has drive shafts76which are largely perpendicular to one another. The electric motor3has a rotor6holding the rotor coil7, cooled by the cooling air71created by the fan wheel8. A stator9of the electric motor3has a stator coil10that is arranged facing the fan wheel8with an obstacle-free space between them. This allows the cooling air71to come into direct contact with a winding end11of the stator coil10. The motor housing4has outlets13for the cooling air71, said outlets having a length L1corresponding more or less to the axial length L2of the fan wheel8. The thickness of the fan wheel8is 30% of the diameter D3of the motor shaft20and effects good heat evacuation away from the motor shaft20to areas located outside of the fan wheel8in a radial direction. The diameter D5of the cooling wheel64corresponds largely to the diameter of the stator coil10at a level perpendicular to the motor's axis of rotation5. The fan wheel8is used to evacuate cooling air in particular from the interior of the motor housing to the exterior.

FIG. 11shows a connection57that transmits the rotation, with a parallel shaft gearbox58and a worm gear pair30as a cross-section along a vertical intersecting plane perpendicular to the motor's axis of rotation5. A gearing worm27engages with a worm gear28which is connected in a torsionally rigid manner via a drive shaft75to a first spur wheel59, which in turn is engaged with a second spur wheel60(not shown). A mating gear66for a worm wheel absorbs counter-forces, so that the gearing worm27cannot break out to the right. A beater74(seeFIG. 1) can be fitted on an appliance head80.

FIG. 12shows a further embodiment of the gear stage33with a parallel shaft gearbox58and a cylindrical crossed helical gear48, wherein a first cylindrical crossed helical gear wheel28engages with a second cylindrical crossed helical gear wheel52, which is connected in a torsionally rigid manner to a first spur wheel59that is engaged with a second spur wheel60. A mating gear67for a spur wheel is arranged opposite the second cylindrical crossed helical gear wheel52relative to the first cylindrical crossed helical gear wheel51, so that said mating gear can absorb counter-forces.

FIG. 13shows a further embodiment of the electric motor-gear stage arrangement31as a longitudinal section with a vertical intersecting plane, wherein a cooling wheel24is fastened on the motor shaft20, said cooling wheel having a highly heat-conducting contact surface26and being connected to the motor shaft20, so that the heat transfer resistance72can be as small as possible. Heat that forms in the gearing worm27or in the rotor coil7of the rotor6, is conducted in the motor shaft20, which has the smallest possible heat conduction resistance73, via the contact surfaces26to the cooling wheel24, which can easily absorb the heat due to its significant wall thickness D2and evacuate the heat efficiently to areas located outside of the cooling wheel24in a radial direction. The cooling wheel24also has fan blades18which generate a flow of cooling air71when the motor shaft20is rotating. The flow of cooling air71cools the cooling wheel24and hence helps to dissipate the heat conveyed by conduction. Furthermore the cooling wheel24creates cooling air71which passes directly over an end of winding11of a stator coil10on the stator9, thereby also cooling the stator9. The motor housing4has intake ports12for the cooling air71, as well as outlets13. The outlets have a first14and a second15edge designed to project inward and outward respectively, thereby creating a first flow channel16and a second flow channel17which encourage acceleration of the cooling air71and in so doing have a beneficial effect on cooling the electric motor3. The cooling wheel24is embodied as a fan wheel8in that the fan blades18are mounted on a backing plate19. The fan wheel8is die-cast. The wall thickness D4of the fan blades18is around 20% of the diameter D3of the motor shaft20. The contact surface26roughly corresponds to the cross-sectional area of the motor shaft20. Dimensioning the fan wheel8in this manner brings about efficient dissipation of the heat generated in the gearing worm27and rotor coil7. The heat is exhausted via the fan wheel8in such a way that particularly rapid and efficient heat dissipation is achieved overall, even when the kitchen appliance1is under a heavy load.

Various further aspects related to the invention are described below. Each of said individual aspects can be applied separately, that is, independently of one another, or may be combined according to choice.

A particularly advantageous electric motor3for an electric motor-driven kitchen appliance1, in particular for an electric motor-driven single or multipurpose kitchen appliance, comprising a motor housing4provided with a rotor6that rotates on a motor's axis of rotation5and has a fan wheel8fastened to it in a torsionally rigid manner, and also provided with a stator9that has a stator coil10, wherein the stator coil10has an end of winding11which stretches parallel to a direction from the motor's axis of rotation5to the fan wheel8, is characterized in that the end of winding11and the fan wheel8are arranged facing one another with a clear space between. In one embodiment the electric motor3is an AC motor. In a further embodiment the electric motor3is a capacitor motor. In a still further embodiment the electric motor3is a shaded pole motor. In one embodiment the motor housing4has intake ports12and outlets13for cooling air71propelled by the fan wheel8, and the length L1of the outlets13along the direction of the motor's axis of rotation5corresponds in the main to the axial length L2of the fan wheel8. In a further embodiment the motor housing4has outlets13for cooling air71propelled by the fan wheel8, said outlets having a first edge14that projects inward into the motor housing4and acts as a first flow channel16for accelerating the cooling air71. Furthermore the motor housing4can have outlets13for cooling air71propelled by the fan wheel8, said outlets having a second edge15that projects outward and acts as a second flow channel17for accelerating the cooling air71. In a development, the fan wheel8comprises fan blades18and has a backing plate19, arranged perpendicular to the motor's axis of rotation5, with a first21and a second22plate surface, the fan blades18being attached to the backing plate19. In a further development the fan blades18arranged together on the first plate surface21, which in particular points straight at the stator coil10, are arranged to be in particular highly heat-conducting. In a special embodiment the maximum nominal rotational frequency of the electric motor3is in a range from 8000 to 20000 revolutions per minute, in particular in a range from 10000 to 15000 revolutions per minute. The maximum bearable, nominal electrical power of the electric motor3can be in a range from 200 W to 1200 W, in particular in a range from 600 W to 900 W.

A particularly advantageous electric-motor driven kitchen appliance1, in particular an electric-motor driven single or multipurpose kitchen appliance, comprises the inventive electric motor3.

A particularly advantageous electric-motor driven kitchen appliance1, in particular an electric-motor driven single or multipurpose kitchen appliance, having an electric motor3that has a stator9and a rotor6that rotates within it on a motor shaft20, wherein the rotor6comprises a rotor coil7and the motor shaft20admits a gearing element23, in particular a gearing worm27or a first cylindrical crossed helical gear wheel51, is characterized in that a metal cooling wheel24, connected in a torsionally rigid manner to the motor shaft20, is provided for cooling the rotor coil7and/or for cooling the gearing element23. Advantageously the cooling wheel24and the rotor6are connected via the motor shaft20in a heat-conducting manner so that when the system is operating at maximum nominal power of the electric motor3, at least 20%, in particular at least 30%, and preferably at least 40% of the heat generated by the rotor coil7is dissipated by heat conduction to the cooling wheel24. In particular the cooling wheel24and the gearing element23are connected in a heat-conducting manner so that when the system is operating at maximum nominal power of the electric motor3, at least 60%, in particular at least 75%, and preferably at least 90% of the heat output introduced on the gearing element23is dissipated by heat conduction to the cooling wheel24. In one embodiment a wall thickness D2of the cooling wheel24is at least 20%, in particular at least 25%, and preferably at least 30% of the diameter D3of the motor shaft20and is in particular in a range from 1.5 mm to 5 mm. In a variant, the sum of the heat transfer resistances72along the heat conduction section25rotor coil—rotor—motor shaft—cooling wheel24is less than the sum of the heat conduction resistances73between the rotor coil7and the cooling wheel24, in particular less than 50%, preferably less than 30%, but particularly preferred as less than 10%. The cooling wheel24and the motor shaft20can be connected to a contact surface26that forms at least 40%, in particular at least 50%, and preferably at least 60% of the outer peripheral surface of a hollow cylinder having a diameter equal to the diameter D3of the motor shaft20and a length equal to the diameter D3of said motor shaft20. Advantageously the cooling wheel24is arranged along the motor shaft20between the rotor coil7and the gearing element23. The gearing element23can be a gearing worm27. In one embodiment the cooling wheel24can be embodied as a fan wheel8and can in particular comprise fan blades18in which their wall thicknesses D4are preferably at least 15%, but particularly preferred at least 20% of the diameter D3of the motor shaft20. Advantageously the cooling wheel24has a backing plate19arranged perpendicular to the motor's axis of rotation5and having a first21and a second22plate surface, wherein the fan blades18are attached to the backing plate19and in particular the thickness D1of the backing plate19is at least 20%, and preferably at least 30% of the diameter D3of the motor shaft20. Advantageously the diameter D5of the cooling wheel24corresponds largely to that of the stator9. In a special embodiment the cooling wheel24consists of aluminum or an aluminum-zinc alloy. The cooling wheel24can be produced by casting or forging. In one embodiment, an attachment29, in particular a puree blender, mixer, shredder, kneader and/or cutter, a crusher or beater74, a drinks mixer, a slicer, a flour sifter, a juicer and/or a meat grinder can be inserted in the kitchen appliance1.

A particularly advantageous arrangement of a worm gear pair30comprises a worm gear28, a gearing worm27, a motor shaft20and a cooling wheel24, wherein the worm gear28engages with the gearing worm27connected in a torsionally rigid manner to the motor shaft20, the cooling wheel24being connected in a torsionally rigid manner to the motor shaft20, and said arrangement is characterized in that the cooling wheel24is made of metal and that when the system is operating at maximum nominal power, at least 60%, in particular at least 75%, and preferably at least 90% of the heat output created on the worm gear pair30is dissipated by heat conduction to the cooling wheel24. The cooling wheel24can be a fan wheel8.

A particularly advantageous electric motor-driven kitchen appliance1, preferably a single or multipurpose kitchen appliance, provided with an insertable electric motor-gear stage arrangement31which comprises an electric motor3having a motor housing4and a gear stage33having a gear case32fastened to said electric motor, is characterized in that the inventive arrangement31comprises a removable reinforcement frame37arranged around the motor housing4and gear case32.

In an embodiment, the reinforcement frame37forms a connection which is in the main torsionally rigid along the connecting line38between the electric motor3and the gear stage33, it being in particular possible for the torsionally rigid connection to withstand torque values within the range 3 Nm to 100 Nm, and preferably within the range 5 Nm to 50 Nm, though the particularly preferred range is from 10 Nm to 20 Nm. The reinforcement frame37can be produced from metal, in particular by punching and pressing or by die-casting. The reinforcement frame37can be screwed to the gear casing32and/or motor housing4using in particular fewer than ten screws39, but in particular fewer than six screws, and preferably only one screw. Advantageously the gear casing32and the motor housing4or the reinforcement frame37comprise connection elements D1, in particular connection projections41, preferably an annular spring, and connection counter elements42, in particular connection receivers43, preferably an annular groove, providing a thread-free means of fastening the reinforcement frame37to the gear casing32or motor housing4. The reinforcement frame37can advantageously have a U-shaped or L-shaped metal section44. Advantageously, an attachment29, in particular a puree blender, mixer, shredder, kneader and/or cutter, a crusher or beater74, a drinks mixer, a slicer, a flour sifter, a juicer and/or a meat grinder can be connected to the kitchen appliance1. The motor housing4and/or the gear casing32can be made from plastic, and in particular from glass fiber reinforced plastic. The gear casing32and the motor housing4can be connected together by means of a bolt flange45, in particular by means of a bayonet lock34.

A particularly advantageous method for producing a kitchen appliance1, in particular the inventive kitchen appliance1, provided with a housing that has an electric motor3fitted with a motor housing4and a gear stage33fitted with a gear casing32, provides that for the purpose of preassembly the motor housing4is connected to the gear casing32in order to form an electric motor-gear stage arrangement31, in such a way that a motor shaft20of the electric motor3is coupled to a drive shaft of the gear stage33in a torsionally rigid manner, and a reinforcement frame37is placed around the gear casing32and the motor housing4so that the gear casing32is connected to the motor housing4in a torsionally rigid manner; and provides that the preassembled electric motor-gear stage arrangement31is then installed in the appliance housing2. The reinforcement frame37can be fastened to the motor housing4and/or the gear casing32using fewer than ten screws39, and in particular fewer than six screws, but preferably only one screw. Advantageously the reinforcement frame37is clipped to the motor housing4and/or to the gear casing32. Advantageously the electric motor-gear stage arrangement31is tested and rated prior to installation in the appliance housing2.

A particularly advantageous electric-motor driven kitchen appliance1, in particular an electric-motor driven single or multipurpose kitchen appliance, having an electric motor3and a gear stage33, wherein the electric motor3has a motor housing4and the gear stage33has a gear casing32, is characterized in that the motor housing4and the gear casing32are connected together with the aid of a bayonet lock34. The motor housing4can be made from glass fiber reinforced plastic or by die-casting. The gear casing32can also be made from glass fiber reinforced plastic or by die-casting. The bayonet lock34has in particular a locking angle46of less than 180°, and in particular of less than 90°, but preferably of less than 45°. In one embodiment the electric motor3has a single direction of rotation47which operates in the closing direction of the bayonet lock34and causes the bayonet lock34to keep in place while the system is operating. Advantageously a torsionally rigid connection between a motor shaft20of the electric motor3and a drive shaft75of the gear stage33is produced with the aid of a worm gear pair30. The worm gear pair30can comprise a motor-related gearing worm27and at least one drive-related worm gear28, and preferably two drive-related worm gears, opposite the gearing worm27. Advantageously the motor housing4and the gear casing32are additionally fixed together by a reinforcement frame37. In one embodiment the bayonet lock34has an axis of rotation which for the most part coincides with the motor's axis of rotation5. Advantageously the kitchen appliance1has a housing2in which the electric motor3connected to the gear stage33can be inserted.

A particularly advantageous electric motor has a first bayonet lock part35for the inventive kitchen appliance1.

A particularly advantageous gear stage33has a second bayonet lock part36for a kitchen appliance1.

A particularly advantageous method for assembling an electric-motor driven kitchen appliance1, in particular the inventive electric-motor driven kitchen appliance1, having an electric motor3and a gear stage33, wherein the electric motor3has a motor housing4and the gear stage33has a gear casing32, is characterized by the following method steps: Preassemble the electric motor3in the motor housing4, preassemble the gear stage33in the gear casing32, connect the motor housing4to the gear casing32with the aid of a bayonet lock34, so that a motor shaft20of the electric motor3is connected in a torsionally rigid manner to a drive shaft75. Advantageously the bayonet lock34is closed by rotating said lock largely about the motor shaft20and moving it a short distance.

A particularly advantageous electric-motor driven kitchen appliance1, in particular an electric-motor driven single or multipurpose kitchen appliance, comprising a planetary gear set54, and having at least one planet wheel55with a planet wheel axis56and a sun gear49having a sun gear axis50, and an electric motor3having a motor shaft20which extends along an axis of rotation5of the motor, wherein the motor shaft20and the planetary gear set54with a connection57that transmits the rotation are coupled together, is characterized in that the connection57that transmits the rotation comprises a parallel shaft gearbox58with a first59and a second60spur wheel and/or a helical-bevel gearbox65with a first63and a second64bevel gear. In one embodiment the parallel shaft gearbox58or the helical-bevel gearbox65has a gear ratio in a range from 10 to 40, and in particular in a range from 20 to 30. In a development, the connection57that transmits the rotation comprises a worm gear pair30with a gearing worm27and a worm gear28or a cylindrical crossed helical gear48with a first51and a second52cylindrical crossed helical gear wheel, wherein the worm gear pair30or the cylindrical crossed helical gear48has a gear ratio in a range from 0.5 to 4, and in particular in a range from 1 to 2. The gearing worm27or the first cylindrical crossed helical gear wheel51can be located on the motor shaft20. The sun gear49can have a sun gear shaft53on which a second bevel gear is located. In one embodiment, the respective drive shafts75of the worm gear pair30, the respective drive shafts76of the cylindrical crossed helical gear48and the respective drive shafts77of the helical-bevel gearbox65are largely perpendicular to one another or the respective drive shafts78of the parallel shaft gearbox58are largely parallel to one another. The sun gear axis50can be largely perpendicular to and coplanar with the motor's axis of rotation5. In a development, for the purpose of absorbing counter-forces the worm gear pair30has a mating gear66for a worm wheel, the cylindrical crossed helical gear48has a mating gear67for a spur wheel, and the helical-bevel gearbox65has a mating gear68for a bevel wheel, relative to which the gearing worm27, the first cylindrical crossed helical gear wheel51, and the first bevel gear63, are opposite the worm gear28, the second cylindrical crossed helical gear wheel52or the second bevel gear64respectively and engage with the gearing worm27, the first cylindrical crossed helical gear wheel51or the first bevel gear63. The planetary gear set54can have a ring gear69arranged coaxially to the sun gear49. The ring gear69can be stationary and can be linked in a torsionally rigid manner to a housing2of the kitchen appliance1. The ring gear69can be cone-shaped. The planet wheels55can be cone-shaped. In one embodiment, the planet wheel axis56and the sun gear axis50intersect at an angle of between 30° and 80°, and in particular at an angle of between 20° and 35°, but preferably at an angle of between 25° and 30°. Advantageously at least two and in particular at least three planet wheels55are provided. Advantageously the planet wheel55has a planet wheel axis56and the gear ratio between a rotation about the sun gear axis50and a rotation about the planet wheel axis56is in a range from 1:1 to 1:10, or in particular in a range from 1:2 to 1:5. The electric motor3can have a maximum nominal rotational frequency in a range from 8000 revolutions per minute to 20000 revolutions per minute, and in particular in a range from 10000 revolutions per minute to 15000 revolutions per minute. In a particular embodiment, the at least one planet wheel55has a holder70for an attachment29, in particular a puree blender, mixer, shredder, kneader and/or cutter, a crusher or beater74.

The invention relates to an electric motor-driven kitchen appliance1, particularly a single or multipurpose electric motor-driven kitchen appliance, comprising an insertable electric motor-gear stage arrangement31which has an electric motor3having a motor housing4and a gear stage33having a gear case32fastened to said electric motor, and provides that the arrangement31comprises a removable reinforcement frame37arranged around the motor housing4and gear case32. The invention also relates to a method for producing an electric-motor driven kitchen appliance1with the aid of a reinforcement frame27. The invention is characterized in that the electric motor-gear stage arrangement31can be tested outside of the housing of the kitchen appliance1and produced in a cost-effective manner, being particularly torsionally rigid due to said removable reinforcement frame37, thereby exhibiting operational reliability.

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