Abstract:
The invention concerns an immersion mixer with an electric motor, a drive shaft, a tube, a bell-shaped housing and a rotary tool. To ease the assembly or disassembly of such a mixer, a cartridge is assembled in the bell-shaped housing so as to be removable. This cartridge includes a shaft guide body, an attaching mechanism, a sealed bearing assembly for receiving the shaft and a sleeve. The cartridge is made in such a way that it is simply necessary to insert or release it through the top of the bell-shaped housing without any action by a specialist in the field being needed.

Description:
RELATED APPLICATION 
     This application claims priority to French Application No. FR 06 50210 filed Jan. 20, 2006. 
     TECHNICAL FIELD 
     This invention concerns an electro-portable food-processing appliance or immersion mixer. In particular, it relates to improvements in the operation of such appliances and facilitating maintenance of the appliance. 
     BACKGROUND OF THE INVENTION 
     Maintenance of appliances may be necessary when a part is worn and needs replacing. Or maintenance may be necessary from the hygienic standpoint, if particles of food have gotten into the appliance during previous use, and need to be cleaned out. Processing appliances are intended for the hotel and restaurant industry and also for family or domestic use. Here, food refers to food in the form of liquids and/or in the form of particles. Food also refers to any type of preparation based on edible or inedible products. Inedible products refers to cosmetic or any other type of preparation. Accordingly, processing appliances can also be intended for use in the pharmaceutical or cosmetic industry, or any other type of industry liable to need such an appliance. 
     One such appliance has a drive shaft, a hollow tube, a bell-shaped housing and a rotary tool. The shaft is inserted through the tube and, at one end is connected to an electric motor driving the shaft in rotation and at an opposite end is connected to the rotary tool. The rotary tool is placed in a position corresponding to the bell-shaped housing. The bell-shaped housing may be removably assembled in a sealing manner onto the tube, and in particular, makes it possible to prevent the tool from touching the bottom or the wall of a recipient, and allows the material to be worked. 
     The bell-shaped housing forms a small portion compared to the tube that forms a large portion. The bell-shaped housing is generally one third to one quarter smaller in size than the tube. The tube and the bell-shaped housing form an overall length that is measured along the tube lengthwise axis. The lengthwise axis is the rotation axis of the appliance about which the tool is put into rotation. The tube and bell-shaped housing are designed for immersion into a food preparation to be processed, over a length corresponding to approximately two thirds of the total length, with the bell-shaped housing totally immersed in the preparation. 
     Patent No. EP 0 925 010 B1 describes such an appliance that includes a stem, a cylindrical bearing placed between the bell-shaped housing and the stem, a sealing means placed on the bearing, and an elastic bellows placed to bear against the stem and connected to the sealing means. The bearing enhances guidance and rotation of the stem with respect to the tube of the appliance. The bellows ensures that the appliance is tight. However, this type of appliance does represent drawbacks. In particular, when it is necessary to clean the appliance, extracting the stem from the bell-shaped housing may cause a deterioration of the bellows, and cleaning the inside of the bearing with a tool, for instance, a knife, can also cause damage to the bearing. 
     SUMMARY OF THE INVENTION 
     The invention proposes a solution to this problem. To achieve this, the invention provides for a monoblock cartridge to be mounted on the appliance, and assembled in the bell-shaped housing. This cartridge has a guide body forming a centering, guidance, and retaining means for the shaft placed between the bell-shaped housing and the shaft, means for forming a sealed bearing receiving the shaft, arranged between the shaft and the guide body, and at least one means for attaching the body to the bell-shaped housing. 
     In one embodiment of the invention, the shaft is made of two parts, a stem and a main cylindrical section. The stem supports the tool at one end and at another is connected to the cylindrical section, the cylindrical section being connected to the motor. When one of the cartridge components is worn, or it becomes necessary to clean the inside of the bell-shaped housing, it is simply necessary to separate an elongated part of the stem from a stem driving hub. Then, the cartridge can be withdrawn from the bell-shaped housing. Finally, the bell-shaped housing, less the cartridge, can be cleaned without any risk of damage to the components designed to work together with the stem and the cartridge can be replaced by a new one if necessary. 
     The invention is an advantageous way for a user or consumer not specializing in the field of this equipment to disassemble or assemble himself the appliance with relative ease. 
     Therefore, one embodiment of the invention is a food processing appliance comprising: an electric motor, contained in a housing with the motor connected to a drive shaft; a hollow tube through which the drive shaft is inserted by a first end of the tube; a bell-shaped housing connected to the hollow tube to a second end of the tube; and a rotary tool attached to the shaft and mounted in the bell-shaped housing. The appliance also includes a monoblock cartridge mounted in the bell-shaped housing, the cartridge having a guide body forming a centering, guidance and retaining means of the shaft arranged between the bell-shaped housing and the shaft, means forming a sealed bearing receiving the shaft, said means being arranged between the shaft and the guide body, and at least one attaching means of the body to the bell-shaped housing. 
     In an alternative embodiment of the invention, the bell-shaped housing and the tube form two separate parts. The bell-shaped housing and the tube are assembled to be removable with respect to one another. In this way, the assembly and disassembly processes of the appliance are facilitated. Assembly and disassembly can be performed by a person who is or who is not specialized in the field of the appliance. Except for the handling of the rotary tool for assembly, it is simply necessary to nest the parts into one another without any special tools being necessary. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood from reading the following description and examination of the accompanying illustrations. The figures are included as illustrations only and must not be considered as limiting the invention in any way. These figures show: 
         FIG. 1  is a schematic representation of an immersion mixer, according to one embodiment of the present invention; 
         FIG. 2  is a sectional view of an immersion mixer, according to one embodiment of the present invention; and 
         FIG. 3  is a schematic representation of an assembly process of an immersion mixer, according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an immersion mixer  1 , according to one embodiment of the present invention. Mixer  1  includes a housing  2 , a hollow tube  3 , and an inside bell-shaped housing  4 . Housing  2  encloses an electric motor (not shown). In the upper part of housing  2  there is a built-in handle  5  which may include a motor operation control switch. The motor is connected to a drive shaft  6 . This drive shaft  6  is housed inside tube  3  and inside bell-shaped housing  4 . Shaft  6  is located in tube  3  with a lengthwise axis of shaft  6  coaxial with a tube lengthwise axis  10 . As depicted in  FIG. 1 , at one end, shaft  6  is attached to the motor, and as depicted in  FIG. 2 , at an opposite end is connected to a rotary tool  9 . The lengthwise axis of the shaft is coaxial with the lengthwise axis  10  of the tube. The shaft lengthwise axis is a rotation axis of the appliance about which the tool is put into rotation. 
     Still referring to  FIG. 1 , tube  3  has an upper end  7  and a lower end  8 . Lower end  8  of tube  3  is opposite to the upper end  7 , placed longitudinally with respect to lengthwise axis  10  of tube  3 . Tube  3  is attached by its upper end  7  to housing  2  and connected at lower end  8  to bell-shaped housing  4 . Here, the term “connected” indicates that bell-shaped housing  4  is attached to tube  3  so that bell-shaped housing  4  and tube  3  form a monoblock part. The term connected also means that bell-shaped housing  4  is assembled to be removable from tube  3  so that bell-shaped housing  4  and tube  3  form two distinct parts that can be separated. 
     Bell-shaped housing  4  is between one third and one quarter the length of tube  3 . Bell-shaped housing  4  and tube  3  form a total length measured along lengthwise axis  10  of tube  3 . Tube  3  and bell-shaped housing  4  are designed to be immersed in a food preparation to be processed over a length corresponding to two thirds of the total length, bell-shaped housing  4  being designed to be immersed entirely in the preparation. 
     Bell-shaped housing  4  forms a bell shape connected to lower end  8  of tube  3 . Bell  4  includes a tubular portion  4 . 1  and a flared portion  4 . 2 . Bell  4  prevents tool  9  from touching the bottom or walls of the recipient and allows the material to be processed. Flared portion  4 . 2  specifically encloses rotary tool  9 . Bell-shaped housing  4  can be assembled to be removable from tube  3  by means of tubular portion  4 . 1  which works together with lower end  8  of the tube to attach bell-shaped housing  4  and tube  3  to one another. To do this, bell-shaped housing  4  and tube  3  may include attaching means allowing them to be secured to one another. In particular, bell-shaped housing  4  may include along an inner surface of tubular portion  4 . 1 , a plastic coating  40  with a shape designed specifically to work together with tube  3 . But, bell-shaped housing  4  may include other similar attaching means suitable for working together with tube  3 . 
     Referring now to  FIGS. 2 and 3 , bell-shaped housing  4  encloses rotary tool  9 . In one embodiment, rotary tool  9  may have a cutting edge. In this case, rotary tool  9  forms at least one transverse cutting edge designed to chop food. In one embodiment, this tool could consist of three blades extending axially out of lengthwise axis  10  of tube  3 . Tool  9  can also be formed by at least one elongated arm for mixing the foods together, or by other types of equivalent food processing tools designed for cutting, mixing or emulsifying the food. 
     As mentioned previously, food refers to any type of material that can be processed by a such appliance, for instance, edible or inedible products. Inedible products may refer to, for instance, cosmetics based on creams or powders, or other products. Here, food also refers to food in the form of particles and/or in the form of liquids. 
     Shaft  6  is formed of a main cylindrical section  6 . 1  and of a stem  11 . Section  6 . 1  is attached to the motor and removably connected to stem  11 . The section is located in tube  3  and possibly partly in bell-shaped housing  4 . The stem is located in bell-shaped housing  4 . 
     Rotational driving of tool  9  by shaft  6  is through stem  11 . Moreover, it is stem  11  that carries tool  9 . Stem  11  and tool  9  are assembled to be removable from bell-shaped housing  4 . Stem  11  also has a lengthwise axis  11  which is coaxial with lengthwise axis  10  of the shaft. Stem  11  has an elongated section  11 . 1  and a drive hub  12 . Elongated section  11 . 1  is removably attached to hub  12  at a rear end  14  of elongated section  11 . 1  and to bearing tool  9  at a front end  15  of elongated section  11 . 1 . Rear end  14  is longitudinally opposite front end  15 , along lengthwise axis  10 . 
     Longitudinally with respect to axis  10 , stem  11  is smaller than main cylindrical section  6 . 1  and is placed in bell-shaped housing  4 . Stem  11  is removably connected to main cylindrical section  6 . 1 . For this purpose, main cylindrical section  6 . 1  includes a coupling cage  13  connected to hub  12  to create a mechanical link and a driving link between elongated section  11 . 1  of stem  11  and main cylindrical section  6 . 1 . This mechanical link is obtained by means of ensuring a rotational link of elongated section  11 . I of stem  11  with main cylindrical section  6 . 1 . Main cylindrical section  6 . 1  may be partially inserted through tubular portion  4 . 1  of bell-shaped housing  4  to allow interconnection between stem  11  and main cylindrical section  6 . 1  in bell-shaped housing  4 . Connected in this way, main cylindrical portion  6 . 1  can thus transmit a rotational movement to stem  11 . 
     According to the present invention, mixer  1  also includes a monoblock cartridge  27  assembled in bell-shaped housing  4 . Cartridge  27  includes a guide body  16  forming a centering, guidance and retention means of shaft  6 , arranged between bell-shaped housing  4  and shaft  6 . Cartridge  27  also includes means for forming a sealed bearing around stem  11  including  21 ,  22 , and  23  arranged between shaft  6  and guide body  16 , and for attaching body  16  to bell-shaped housing  4 . According to the invention, cartridge  27  is assembled to be removable in bell-shaped housing  4 . But cartridge  27  could be assembled permanently in bell-shaped housing  4 . In the preferred embodiment of  FIG. 2 , cartridge  27  is arranged around elongated section  11 . 1  of stem  11 . But, this cartridge could be placed anywhere on shaft  6 . 
     Body  16  forms a cylinder having an outer face  17  on which external sealing means are positioned, such as  18  and  19 , by means of which body  16  works together with bell-shaped housing  4  to provide tightness for cartridge  27  with respect to bell-shaped housing  4 . These sealing means also work together to attach cartridge  27  to bell-shaped housing  4 . Body  16  includes an internal face  20 , to which are attached the sealing means forming a sealed bearing accommodating the stem, such as  21 ,  22  and  23 , through which body  16  works together with stem  11 . 
     The external sealing means may be formed by at least an O-ring. In the example of  FIG. 2 , cartridge  27  has a first O-ring  18  and a second O-ring  19 . Each of these seals forms a molded rubber ring. These seals work together with bell-shaped housing  4  and body  16  so that each of them provides static sealing and dynamic sealing between bell-shaped housing  4  and body  16 . Each of the two seals  18  and  19  is arranged partially in corresponding peripheral grooves  29  and  30 . Each of these grooves is formed from the outer face  17  of body  16 . First seal  18  and second seal  19  are positioned respectively in groove  29  and in groove  30  so that the two seals are placed to bear against body  16  and against bell-shaped housing  4  when cartridge  27  is inserted into bell-shaped housing  4 . That is why these external sealing means also contribute to attachment. 
     It is also possible to have these seals formed by bell-shaped housing  4  while being intended to be housed in grooves that would be formed from an inner face  34  of a housing  39  in bell-shaped housing  4 . Housing  39  could also be of stainless steel and placed astride and lengthwise on tubular portion  4 . 1  of bell-shaped housing  4  and along the flared portion  4 . 2  of bell-shaped housing  4 . Housing  39  forms a bore  41  through which cartridge  27  can penetrate. Housing  39  forms the internal face  34  containing more specifically bore  41 . 
     To prevent the two seals  18  and  19  from breaking free from their respective housing, or to prevent these two seals from deteriorating when the cartridge is assembled, it can be arranged so that housing  39  has a chamfer  45  or a radius  45 . In the preferred embodiment of the invention, this chamfer  45  is placed at the entry to housing  39  of bell-shaped housing  4 , along which the outer seals slide when the cartridge  27  is inserted into housing  39  of bell-shaped housing  4 . This chamfer or radius  45  is formed at entry  45  of housing  39  or at a point of housing  39  close to tube  3  or to end  8  of tube  3 , longitudinally with respect to lengthwise axis  10 , remote from rotary tool  9 . Chamfer  45  is formed at a junction between internal face  34  and a surface provided by shoulder  37 . But this chamfer can be situated at an opposite end of the housing, near tool  9  and remote from the end  8  of tube. 
     External sealing means  18  and  19  are designed to be placed to bear against the internal face  34  of housing  39  of bell-shaped housing  4 . The external sealing means can comprise any other type of means that provide sealing, and possibly attachment, equivalent to those provided by O-rings. 
     The O-rings also contribute to recentering the cartridge while providing alignment on shaft lengthwise axis  10  of the main cylindrical section  6 . 1  lengthwise axis, with the lengthwise axis of the stem. 
     The means for forming a sealed bearing includes at least one internal sealing means  23 . The term internal sealing refers to the sealing between the outside environment and the means forming the bearing. In the example of  FIG. 2 , the means for forming a sealed bearing is an internal seal  23 . Other means equivalent to a seal can be used. 
     Internal seal  23  is formed by a plastic or elastomer material. Seal  23  can be formed by a lip seal forming a “U” which includes a flexible bearing edge referred to as lip  23 . 1  and another fixed portion  23 . 2 . This refers to a lip seal. This seal could include more than one lip. But, this seal could be replaced by any other type of means providing an equivalent function. This seal  23  is designed for attachment to inner face  20  of body  16  by its fixed portion  23 . 2 , and is intended to be placed in contact with, or to bear against, the cylindrical surface formed by stem  11  by its flexible portion  23 . 1 . 
     Cartridge  27  is arranged around stem  11 . But cartridge  27  could also be situated around section  6 . 1 . In the one embodiment of the invention, cartridge  27  is locked in its translation inside bell-shaped housing  4  co-linearly with the lengthwise axis of stem  11 , in one direction by stop  37  of the bell-shaped housing end, and in the opposite direction by at least one stopping means, such as at least one extruded ring  31 , of cartridge  27 , working together with at least one groove  33  in bell-shaped housing  4 . The stopping means locks the body in bell-shaped housing  4  in such a way that cartridge  27  can be removed by moving the stopping means to unlock cartridge  27  and allow the withdrawal of cartridge  27  through bell-shaped housing  4 . 
     Indeed, elastic-translation locking of cartridge  27  can be obtained with respect to lengthwise axis  10  in bell-shaped housing  4 , from the housing to the tool, by bearing of a collar  48  consisting of the body of the cartridge against a shoulder  37  of bell-shaped housing  4  and from the tool to the housing by the bearing of at least one extruded ring  31  of cartridge  27  against a bearing surface  33 . 1  or a stop in housing  39 . Collar  48  extends radially at least in part on a perimeter of the body in a direction opposite to the axis of stem  11  and is formed at one end of that body. Collar  48  is built in such a manner that the body is stretching at the point where the collar is formed. In one example, collar  48  is formed on a perimeter of a material formed by the body. Shoulder  37  is formed by housing  39 . Cartridge  27  is retained along lengthwise axis  10  from housing  2  to tool  9  by means of collar  48  positioned to bear against shoulder  37 . Locking cartridge  27  in translation in this way by the bearing of collar  48  against the shoulder guarantees that cartridge  27  does not come out of housing  39  and that cartridge  27  does not fall into the food preparation. This translation locking can also guarantee that main cylindrical section  6 . 1  is retained in tube  3  and in bell-shaped housing  4  without any risk of falling into the preparation. Translation locking also ensures that the tool is held at the right height with respect to bell-shaped housing  4 . Cartridge  27  includes at least one extruded ring  31 . Extruded ring  31  is placed in a peripheral notch  32  formed from outer face  17  of body  16 . Extruded ring  31  is placed in notch  32  and emerges partially from outer surface  17  of body  16  and floats at least radially in notch  32 . Extruded ring- 31  positioned in this way with respect to notch  32  is designed to be placed to bear elastically, relatively perpendicularly, with respect to axis  10  against bearing surface  33 . 1  of housing  39  during the insertion of the cartridge into bell-shaped housing  4 . In this way extruded ring  31  also works together with stopping the cartridge in rotation because of the friction of the extruded ring against housing  39 . 
     Bearing surface  33 . 1  forms a plane perpendicular to lengthwise axis  10 . This bearing surface  33 . 1  is formed by a groove  33  hollowed into inner face  34  of housing  39  of bell-shaped housing  4 . As produced in the embodiment of  FIG. 2 , bearing surface  33 . 1  is made in such a way that the bearing of extruded ring  31  against this bearing surface  33 . 1  prevents cartridge  27  from being moved from tool  9  to housing  2  longitudinally with respect to lengthwise axis  10 . Cartridge  27  and bell-shaped housing  4  could include other types of attaching means to provide a function equivalent to those of the extruded ring and the groove. For instance, the bell-shaped housing and cartridge could be attached by screwing, by a bayonet arrangement, or by a collar forming a stop. 
     In the embodiment described immediately above, cartridge  27  is therefore locked elastically by means of the extruded ring. But cartridge  27  could be stopped in a manner that is not elastic, for instance by a pin inserted through bell-shaped housing  4  and cartridge  27 , transversally, or else by a setscrew also inserted through bell-shaped housing  4  and cartridge  27  (examples not illustrated). 
     To lock cartridge  27  in the opposite direction, that is from the housing to bell-shaped housing  4 , cartridge  27  is placed to bear against shoulder  37  of bell-shaped housing  4 . Indeed, a bearing surface formed by collar  48  of cartridge  27  is placed to bear against shoulder  37  of bell-shaped housing  4 . The shoulder results from the shape of at least one niche  36  formed by the housing. Niche  36  forms shoulder  37 . Shoulder  37  defines the recess. Cartridge  27  is placed to bear against this shoulder  37  through body  16 . Cartridge  27  may also contain at least one self-rotating ear  35 , as depicted in  FIG. 3 . Ear  35  is formed of collar  48  and extends radially and in the opposite direction to lengthwise axis  10 . If the collar is partially peripheral, the collar will also play an anti-rotation part and the forming of the ear then becomes optional. 
     Cartridge  27  is therefore also stopped from rotating in bell-shaped housing  4  by the insertion of ear  35  in niche  36 . Niche  36  therefore has a shape that adjusts to the end of the body provided with the collar, and possibly the ear. 
     Extruded ring  31  and groove  33  on the one hand, and collar  48 , ear  35  and shoulder  37  on the other, are positioned with respect to one another so that the insertion of cartridge  27  is preferably carried out by the top of bell-shaped housing  4 , i.e. tubular portion  4 . 1  of bell-shaped housing  4  or by upper end  4 . 4  of bell-shaped housing  4 . Upper end  4 . 4  of bell-shaped housing  4  is an end designed to work together with lower end  8  of tube  3 . Bell-shaped housing  4  also has a lower end  4 . 3  designed to accommodate rotary tool  9  and which is kept away from lower end  8  of tube  3  with respect to upper end  4 . 4  of this end  4 . 
     In one embodiment, it is possible to insert and withdraw cartridge  27  through lower end  4 . 3 . 
     According to the invention, cartridge  27  also includes a sleeve  24  placed between elongated section  11 . 1  of stem  11  and the means forming sealed bearing  21 ,  22 , and  23 . 
     Sleeve  24  forms a case protecting the elongated section of stem  11  and covers at least a portion of elongated section  11 . 1  of stem  11  along which friction can occur. In particular, sleeve  24  covers at least a portion of the surface of elongated section  11 . 1  of stem  11  designed to work with flexible portion  23 . 1  of internal seal  23 . But sleeve  24  may also cover a larger surface of elongated section  11 . 1  of stem  11 . Preferably, sleeve  24  covers the entire surface of stem  11  designed to work together with the means, forming a sealed bearing as per  FIG. 2 . 
     Sleeve  24  forms a conduit or pipe attached to the elongated section  11 . 1  of stem  11 . The term attached to the stem means that sleeve  24  is held on elongated section  11 . 1  of stem  11  by the binding forces that exceed the binding forces that exist between flexible portion  23 . 1  of internal seal  23  and sleeve  24  and ensure tightness between sleeve  24  and elongated section  11 . 1  of stem  11 . Thus, sleeve  24  is attached to elongated section  11 . 1  of stem  11  so that the rotation of elongated section  11 . 1  of stem  11  causes sleeve  24  to rotate. Sleeve  24  forms a protection case on elongated section  11 . 1  of stem  11  and also forms a sealing means compared to the elongated section  11 . 1  of stem  11 . 
     The means forming the reception sealed bearing also form means of facilitating the rotation of the stem elongated section  11 . 1  compared to body  16 . In particular, these means that facilitate the rotation of the elongated section can be formed by at least one bearing such as  21  and  22 ,  FIG. 2 . But these means could be formed by any other means ensuring an equivalent function to that provided by the bearings. For instance, there could be a ring lined on the inside with a lubricating product, instead of the bearings, to work with the stem or the sleeve while being attached to the body. 
     In the case of  FIG. 2 , a first bearing  21  and a second bearing  22  are attached to the stem  11  or sleeve  24  and inner face  20  of body  16 . The attachment of these bearings to the sleeve advantageously offers the locking of the sleeve in translation compared to body  16  of cartridge  27  along lengthwise axis  10 . Internal seal  23  is held stationary, fixed by its fixed portion  23 . 2  on the body, and in contact with the sleeve or bearings through the other flexible portion  23 . 1  against sleeve  24 . Internal seal  23  and sleeve  24  are unlikely to move longitudinally with respect to one another compared to axis  10 . Locking sleeve  24  in translation in this way prevents any deterioration of internal seal  23 , and especially any deterioration of the flexible portion of internal seal  23 . Internal seal  23  is placed at a point of cartridge  27  near rotary tool  9  longitudinally with respect to axis  10  whereas the first bearing means  21  and the second bearing means  22  are located behind seal  23  with respect to axis  10 , internal seal  23  being situated between tool  9  and the bearing means. 
     Sleeve  24  comprises at least one hardened or lined friction track  28 . This track  28  is formed on a surface of the conduit formed by sleeve  24 . This friction track  28  decreases the wear on sleeve  24  due to the friction of seal  23 . This track is located at a point of sleeve  24  against which the friction takes place. In particular, track  28  is situated at a point of the sleeve conduit facing internal seal  23 . Internal seal  23  is designed to be placed to bear on its flexible portion against this track. This track  28  may be obtained by local physical, chemical, heat or other treatment of the surface of sleeve  24  consisting in modifying a surface structure of the material formed by the sleeve conduit. Otherwise, track  28  may be obtained after the application of a coat of material to the conduit of sleeve  24 . Some such treatments may be accumulated. The purpose of this treatment is to harden and/or decrease the track friction surface coefficient to minimize the wear and extend the internal sealing capacity. Other equivalent treatment methods can be used at this point to achieve this modification of the surface structure of the conduit formed by the sleeve. 
     Track  28  can also be the result of a ring mounted permanently on the conduit formed by sleeve  24 . On the outer face of this ring in contact with flexible portion  23 . 1  of seal  23 , it can be advantageous to apply at a least one of the treatment methods intended to improve the friction surface life of this ring. 
     Sleeve  24  includes, longitudinally with respect to lengthwise axis  10  leading from housing  2  towards tool  9 , an upper end  25  and a lower end  26 . Hardening track  28  can extend from lower end  26  of the sleeve, on the one hand, as far as the first bearing means  21 , on the other. This track increases the lifetime of the sleeve and therefore of mixer  1 . But, this track could extend all the way along the conduit of sleeve  24 . 
     In one embodiment of the present invention, lower end  26  forms a dropped edge and upper end  25  forms a shoulder  25 . 1 . The dropped edge extends radially with respect to the lengthwise axis in a direction opposite to it. This dropped edge can be obtained by riveting or by any other technique so that an equivalent shape can be obtained in the lower end. When the track is a ring, track  28  can also be sandwiched between the dropped edge of the sleeve and the first bearing. In this way, the track is also locked in longitudinal translation and rotation with respect to axis  10  and with respect to the seal. Lower end  26  forms a stop against which a widened shape  43  of the elongated section of stem  11  is placed. This widened shape  43  corresponds to a local increase in the diameter of the stem. Dropped edge  44  formed by lower end  26  helps with the tightness of stem elongated section  11 . 1  with respect to the sleeve by the pressing of the widened section  43  against dropped edge  44 . 
     Shoulder  25 . 1  results from a deformation of the conduit formed by sleeve  24  so that this shoulder forms a collar extending all the way around lengthwise axis  10  perpendicular to lengthwise axis  10  and in a direction opposite to stem  11 . Shoulder  25 . 1  can also be formed by stripping away a block of metal or any other means to obtain a stopping system equivalent to that of shoulder  25 . 1 , for instance, an elastic ring. Or, shoulder  25 . 1  can be formed by stripping away any other type of material. Shoulder  25 . 1  is formed so that hub  12  is placed to bear against shoulder  25 . 1  longitudinally, with respect to lengthwise axis  10 , while being attached to elongated section  11 . 1  of stem  11 . Hub  12  is centered on part of the sleeve between shoulder  25 . 1  and rear end  14  of elongated section  11 . 1  of stem  11 . Hub  12  is screwed onto elongated section  11 . 1  of stem  11  and placed to bear against shoulder  25 . 1 . Upper end  25  also forms an end against which elongated section  11 . 1  of stem  11  is placed to bear longitudinally with respect to axis  10  of stem  11  from housing  2  towards tool  9 . Hub  12  also corresponds to another local increase in the diameter of stem  11 . Sleeve  24  is connected to elongated section  11 . 1  of the stem so that stem  11  and sleeve  24  are integral in rotation, while the elongated section of stem  11  and the sleeve are immobilized in translation with respect to one another, and the sleeve also forms a sealing means with respect to stem  11 . Stem  11  is attached to bell-shaped housing  4  while remaining removable. 
     Sleeve  24  is arranged as follows in body  16 . Bearings  21  and  22  and sealing means  23  are first attached to inner face  20  of the body. Then the sleeve is placed to bear with the shoulder against second bearing  22 . Friction track  28  forming a bush around the sleeve conduit is then positioned to bear against first bearing  21 . Subsequently lower end  26  is formed to obtain the dropped edge. The ring forming track  28  is sandwiched between the dropped edge and the first bearing means. The sleeve is then retained on bearings  21  and  22 . 
     Stem  11  includes a deflector  38  located between rotary tool  9  and cartridge  27 . Deflector  38  forms a washer attached to the stem and which extends from stem  11  radially with respect to lengthwise axis  10  over a surface area covering at least one transversal section of internal seal  23 . Deflector  38  deviates the flow of food and forms a screen against the insertion of food that could be insinuated, under the effect of the pressure flow, into the bearing means of cartridge  27 . This deflector also forms a screen against any possible deterioration of internal seal  23  caused by the ejection pressure of fluid against seal  23 . Accordingly, in one embodiment, it is arranged for the deflector to overhang cartridge  37  and housing  39 . In the example of  FIG. 2 , deflector  38  forms a flat washer but could also assume other shapes to provide a similar function. 
     To prevent cartridge  27  from drifting towards tube  3  after the impact of tool  9  against the food, cartridge  27  may also have an upper collar  44  capable of bearing against coupling  47 , forming a stop. Upper collar  44  is formed by the body from collar  48  while extending relatively longitudinally with respect to lengthwise axis  10  and in the direction of the housing. Coupling  47  forms an intermediate part capable of connecting bell-shaped housing  4  to tube  3 . The bearing of cartridge  27  on the coupling makes it possible to lock cartridge  27  in height, in the direction of tube  3 . Coupling  47  can be integral with tube  3  at end  8  of the tube. 
     The assembly process of one embodiment of a mixer of the present invention is depicted in  FIG. 3 . Cartridge  27  is first inserted into bore  41  of bell-shaped housing  4 , through upper end  4 . 4  of bell-shaped housing  4  until extruded ring  31  bears in slot  33  and until collar  48 , and possibly ear  35 , bear against corresponding shoulder  37 . Cartridge  27  is inserted into bell-shaped housing  4  with external face  17  of body  16  pressed against internal face  34  of housing  39 . 
     Then, rotary tool  9  is assembled into cartridge  27 , while elongated section  11 . 1  of stem  11  is inserted into cartridge  27 . Elongated section  11 . 1  of stem  11  must slide until elongated section  11 . 1  is placed to bear against the lower end  26  of sleeve  24 . To ensure better guidance of elongated section  11 . 1  through cartridge  27  during assembly, the conduit formed by sleeve  24  is preferably rigid. 
     Then driving hub  12  is attached to elongated section  11 . 1  of stem  11  through upper end  4 . 4  of bell-shaped housing  4 . If bell-shaped housing  4  is removable with respect to tube  3 , bell-shaped housing  4  comprising such a cartridge  27  and such a tool  9  is then attached to tube  3  while connecting stem  11  to main cylindrical section  6 . 1  fitted with a driving cage  13 . 
     To disassemble this type of mixer, bell-shaped housing  4  is disassembled from tube  3 , then elongated section  11 . 1  is disassembled from hub  12 . Then, elongated section  11 . 1  is removed from bell-shaped housing  4  by pulling on elongated section  11 . 1  of stem  11  until the elongated section is extracted from cartridge  27 . Cartridge  27  is removed from bore  41  of bell-shaped housing  4  through upper end  4 . 4  of bell-shaped housing  4 . To do this, cartridge  27  is pushed, with the fingers of one hand, for instance, inserted through lower end  4 . 3  of bell-shaped housing  4 , from tool  9  to housing  2 , until extruded ring  31  elastically comes free of groove  33 . Cartridge  27  is made to slide against internal face  34  of housing  39  as far as the extraction of cartridge  27  from bell-shaped housing  4 . 
     The assembly of sleeve  24  and internal seal  23 , locked in translation in body  16  of cartridge  27  along lengthwise axis  10  prevents any translation movements of the friction track of sleeve  24  with respect to flexible portion  23 . 1  of internal seal  23  in contact with the friction track. Translation locking of the track with respect to the seal prevents any deterioration of flexible portion  23 . 1  of the seal. 
     The present invention also includes methods of using a mixer of this type as described above. 
     For reasons of cost and ease of assembly, cartridge  27  may be assembled in an appliance whose bell-shaped housing  4  and tube  3  form a single monoblock part. 
     In some embodiments, the cartridge may or may not be equipped with a sleeve. 
     In one embodiment, track  28  may also be formed by elongated section  11 . 1  of stem  11  in the event track  28  results from local treatment of material formed by the stem. In another embodiment, track  28  may be produced by a ring attached to the elongated section of stem  11 .