AU713926B2

AU713926B2 - Kitchen appliance

Info

Publication number: AU713926B2
Application number: AU49489/97A
Authority: AU
Inventors: Georg Borger; Karl-Heinz Kamprath; Georg Mothrath
Original assignee: Braun GmbH
Current assignee: Braun GmbH
Priority date: 1996-11-04
Filing date: 1997-10-22
Publication date: 1999-12-16
Anticipated expiration: 2017-10-22
Also published as: PL184529B1; DE19645309A1; ES2147982T3; WO1998019585A1; DE59701538D1; PL333053A1; AU4948997A; EP0935436A1; ATE192029T1; EP0935436B1

Abstract

The invention concerns a kitchen appliance comprising an electric drive motor (9) which is disposed in a housing (1, 3, 4) substantially perpendicular to the surface on which said appliance stands. The drive motor (9) is surrounded by a housing part (3), ventilation apertures (13, 14) being formed in the housing (1, 3, 4). The drive motor (9) is not provided with fan wheels. Viewed in the longitudinal extension (X) of the drive motor (9), the ventilation apertures (13, 14) are disposed substantially in the region of the opposite ends of the housing part (3). The ventilation aperture (14) through which the hot air (18) is discharged is disposed above the drive motor (9). As a result, even without fan wheels, an air flow is produced by convection from the air inlet apertures (13) to the air outlet apertures (14), so rendering the appliance more economical and quieter yet providing adequate cooling of the drive motor (9).

Description

WO 98/19585 PCT/EP97/05824 06057 Kitchen Appliance This invention relates to a kitchen appliance, comprising a drive motor, a processing tool driven by the drive motor for the processing of food materials, a housing surrounding the kitchen appliance, and a cooling arrangement producing a cooling air current for the drive motor, said cooling arrangement having an air directing channel in which the drive motor is disposed, and provision being made in the housing for air inlet and air outlet apertures between which the air directing channel is formed.

Kitchen appliances are used for performing a wide variety of daily kitchen chores such as, for example, kneading, mixing and beating, cutting, shredding, grating, blending, to name just the most important ones. For these purposes, free standing kitchen appliances suitable for universal use are employed among others.

Depending on the food materials that need to be comminuted or kneaded, for example, a high amount of energy must be expended with the result that such kitchen appliances require powerful drive motors which operate reliably also under continuous duty. The drive motors surrounded by the housing of such kitchen appliances generate great amounts of heat, particularly under load, which has to be carried off from the appliance. For this reason, a fan wheel is provided for driving connection with the drive motor to keep air circulating in particular around the drive motor during operation of the appliance, the air being aspirated through air inlet apertures for cooling the drive motor.

Conventionally, the fan wheel is mounted directly on the drive shaft of the drive motor. A kitchen appliance showing such an arrangement of the fan wheel on the drive shaft of the drive motor is known from U.S. Pat. No. 4,309,631. The kitchen appliance therein described is a kitchen mixer having the drive 1 P:\WPDOCS\DYS\SPECIE\716330- 16/9/99 -2motor extend horizontally with its drive shaft. The driving force is transmitted through an angular gear mechanism to a vertically upstanding shaft whose free end is engageable with a tool.

To avoid the provision of a separate fan wheel that is mounted directly on the shaft, according to DE-Al 34 08 693 a wheel over which a belt is guided is configured as fan wheel. In this arrangement, it is preferably not the pulley that is mounted directly on the drive shaft of the drive motor, but rather the pulley which is connected with the shaft that mounts and drives a processing tool, because conventionally this latter pulley has a greater diameter than the pulley mounted on the drive shaft of the drive motor.

Cooling arrangements in the form of fan wheels have the disadvantage of adding to the weight of the mass to be moved by the drive motor, regardless of whether the fan wheels 9 •t are mounted directly on the drive shaft of the drive motor, are connected with pulleys or form S 15 part thereof. Unless worked to high precision, fan wheels produce an unbalance, causing 4. 0 the appliance to vibrate and produce noise during operation.

o9o* From DE-A 41 15 471 there is further known a kitchen appliance in which the drive motor is cooled by a separate fan motor with fan wheel. This arrangement is, however, 20 relatively expensive.

It is therefore an object of the present invention to provide a kitchen appliance comprising an electric drive motor, in which the problems of the prior art attendant upon using a fan wheel are alleviated while yet enabling the drive motor to be cooled effectively and run quietly.

According to one aspect of the present invention there is provided a kitchen appliance comprising: a drive motor housing section which includes an internal chamber having an internal wall;

I_

P:\WPDOCS\DYS\SECIE\716330- 16/9/99 -3a drive motor disposed within said chamber; a processing tool adapted to be driven by said drive motor for processing food materials; a cooling arrangement for cooling the drive motor, the cooling arrangement including one or more air inlet apertures and one or more air outlet apertures and an air directing channel between the air inlet and outlet apertures, the air directing channel being within said chamber and adjacent the drive motor, the arrangement being such that the cooling air current within the air directing channel is produced by hot air rising in the channel from the inlet to the outlet apertures.

When the air directing channel and the drive motor are arranged to extend horizontally and the air inlet and air outlet apertures extend on the air directing channel in superposed position, the resulting upward flow for cooling the drive motor is already good (claim 2).

SIn the this arrangement, however, it is desirable that the air inlet apertures be formed 15 essentially beneath, and the air outlet apertures above, the drive motor on the air directing S. channel.

To support the guiding of the air with an effective heat transference along the drive motor, it is necessary for the air directing channel to extend perpendicularly to the support 20 surface of the kitchen appliance in the normal position of the g o, WO 98/19585 PCT/EP97/05824 06057 appliance (claim In this arrangement, the air inlet apertures may be provided essentially beneath the drive motor, for example, in the base plate of the appliance. To obtain a slim design of the tubular housing, the axis of the drive motor has to be aligned such as to extend approximately parallel to the longitudinal axis of the tubular or tower-like housing; in this arrangement it is an advantage to mount a relatively slim drive motor in the tubular housing so that when looking in the direction of the air flow and the axis of the drive motor, a long heat exchange zone is realized between the air current and the surface of the motor housing.

A particularly simple configuration of the air directing channel is accomplished with the features of patent claim 4. In this configuration, the channel's passage is formed by the annular chamber between the drive motor and the housing.

To circulate the air flow around the entire drive motor, that is, viewed in a radial direction to the motor axis, claim provides for the air directing channel to be configured as a tubular section formed between the outside of the drive motor and the inner wall of the tower-like housing. As mentioned in the foregoing, in this arrangement the cross section of the annular chamber may be dimensioned such that a defined convection air current results from the air inlet apertures along the tubular section to the air outlet apertures. In this arrangement, the form of the air directing channel is independent of the form of the inner wall of the housing.

In order to support the air flow in the direction of the longitudinal dimension of the tubular housing still further, it is preferable according to claim 6 that a free space be present above the drive motor, meaning that the tubular housing should be extended in length beyond the longitudinal dimension of the drive motor, the hot air then flowing into said space to exit 4 WO 98/19585 PCT/EP97/05824 06057 from there through the air outlet apertures. In this arrangement, the space above the drive motor serves as a collecting space for the hot air from where it is subsequently directed to the outlet apertures through ducting devices or similar guide paths on which it is eventually discharged to atmosphere. Hence the free space also serves to improve the air flow out of the housing. At the same time, the wall of the free space may also store additional heat energy, delivering it to the outside by thermal radiation. Viewed in the direction of the axis, the drive motor may occupy different positions in the interior of the tower-like housing, preferably however the length of the tower-like housing should be coordinated with the drive motor in such manner that the drive motor occupies only part of the space in the tower-like housing.

To introduce an optimal air current into the tower-like housing while at the same time ensuring a uniform low friction air flow over the entire outer surface of the drive motor, it is preferable according to claim 8 to dispose the air inlet apertures essentially vertically beneath the drive motor in the base plate; these apertures may also be a combination of radial (claim 7) and axial apertures relative to the axis of the drive motor. Such a configuration of holes operates to supply air uniformly around the drive motor, circulating the air around it from all sides. However, the apertures may also be provided both vertically beneath the drive motor and laterally thereof in the base plate. In this arrangement, the air inlet aperture may also be formed on the base plate at a higher level than the lower end of the drive motor, so that then the air directing channel is extended in length by an amount equaling the difference between the higher level location and the height of the air inlet aperture in the appliance base. Owing to the stack effect, cold air is still aspirated from the higher-level air inlet aperture.

5 WO 98/19585 PCT/EP97/05824 06057 To generate a powerful convection air current, it is preferable according to claim 9 to provide the housing with an asymmetrical cross section normal to the axis of the drive motor or normal to the axis of the housing, so that when viewed in the longitudinal direction of the tubular housing, niche-type corner spaces are formed which are distributed around the drive motor.

This means that individual eccentric spatial sections for the air flow are formed which are distributed around the drive motor, enabling a greater amount of hot air to be received in this area. The eccentric spatial sections also increase the radiating surface on the housing, without the flow being significantly aggravated by the increased corner spaces.

According to claim 10, suitable asymmetrical cross sections are ellipsoidal, rhomboidal or oval cross sections. In combination with a symmetrical cross section, it should however be also ensured that the housing is dimensioned such that a free circular ring shaped space is still maintained around the entire drive motor (claim 11).

With the features of claim 12, the drive motor is cooled optimally by both convection and radiation. Radiation is accomplished by a particularly large outer surface of the housing central portion surrounding the drive motor when this portion is preferably oval in cross section. Such a form can still be manufactured with ease with a smooth surface. The material of the housing is preferably plastic. For improved heat storage and heat dissipation, however, metal could also be employed.

Further details and features of the present invention will become apparent from the description of an embodiment with reference to the accompanying drawings. In the drawings, FIG. 1 is a front side view of a kitchen appliance with a tubular or tower-like housing extending upwardly on the rear longitudinal side of the housing; 6 WO 98/19585 PCT/EP97/05824 06057 FIG. 2 is a sectional view taken on the line II-II of FIG.

1; FIG. 3 is a top plan view of the kitchen appliance of FIG.

1, as seen looking from the direction of the arrow III of FIG.

1; and FIG. 4 is a sectional view taken on the line IV-IV of FIG.

3.

The kitchen appliance of the type illustrated in FIGS. 1 to 4 has a housing 1 with a base plate 2 resting on a support surface 31 and a housing central and upper portion 3 and 4, respectively, the latter being formed by cover plate 4. Provided at the front of the housing 1 is a sloping control panel 5 with two recesses 6 for receiving control elements, not shown, in the form of control buttons for activation and control of the speed of a drive motor 9.

It is to be noted that the individual Figures show the kitchen appliance essentially only with its housing i, that is, without the mechanical and/or electrical components, while however the drive unit is shown schematically in the form of the electric drive motor 9 which is mounted on a metal mounting plate 22 carrying a transmission mechanism (not shown), which mounting plate in turn takes support upon the base plate 2. The transmission mechanism serves to drive drive shafts 27, (FIGS. 2 and 3) which project from openings 8, 23 in the base part 34 of the housing central portion 3.

The kitchen appliance has two receiving sockets 7, 24. The receiving sockets 7, 24 are each capable of mounting a respective processing container 25, 35 (indicated schematically in FIGS. 2 and 1) such as, for example, a mixing or blending container, which is centrally located and secured therein and has in its interior a rotary push-on shaft 28 connecting the 7 WO 98/19585 PCT/EP97/05824 06057 processing containers 25, 35 to the drive shaft 27, 30 so that, again through the push-on shaft 28, a processing tool 29 such such as, for example, a cutting blade or a mixing tool, which is adapted to be fitted to the push-on shaft 28 in the processing container 25, 35, can be driven. The two receiving sockets 7, 24 are dimensioned such as to receive a different size of processing container 25, 35 each, with the associated processing tools 29 operating, where applicable, at different speeds, the smaller diameter processing container 25 and the larger diameter processing container 35 being illustrated in dot-and-dash lines in FIG. 1. The larger processing container 35 is centered, held and coupled to the second drive shaft 30 in the receiving socket 24.

The drive shafts 27, 30 extending through the respective openings 8, 23 are driven by the drive motor 9 illustrated schematically in FIGS. 2, 3 and 4. The drive motor 9 has its motor axis 10, which is indicated in FIG. 2 by the dot-and-dash line, extend vertically to the base plate 2 in the direction X.

Secured to the drive shaft 11 of the drive motor 9 is a pulley, not shown, which is in engagement with one or two drive belts (not shown) which is or are guided, through further pulleys associated with the drive shafts 27, 30, such that rotation of the drive motor 9 causes rotation of the drive shafts 27, 30 at a speed reducing or speed increasing ratio in accordance with the size of the pulleys. The pulleys and belts form the transmission mechanism of the kitchen appliance.

The drive motor 9 is a fanless drive motor, meaning that there is no fan wheel provided to supply cooling air to the drive motor 9. Nor is a fan wheel associated with any one of the pulleys or any other rotary part. The drive motor 9 is preferably cooled by a convection air current (shown by the arrows 18 in FIG. 2) which is directed past the outside of the drive motor 9 through an air directing channel 12 provided 8 WO 98/19585 PCT/EP97/05824 06057 between the outside 32 of the drive motor 9 and the inner wall of the tubular housing portion 3, 4. Air inlet apertures 13 are provided in the base plate 2 directly beneath the drive motor 9. According to FIG. 4, these air inlet apertures 13 are elongate slots spaced uniformly on circles concentric with the axis 10 of the drive motor 9. Air inlet apertures 33 of like construction are formed beneath the receiving socket 7 to enable a maximum of cooling air to be aspirated and, where applicable, to provide for cooling of the transmission mechanism (not shown) as well.

At the junction of the cover plate 4 with the housing central portion 3, relatively amply dimensioned air outlet apertures 14 in the form of lateral discharge slots are provided, forming an exit for an air flow generated in the housing 1 along the arrows 18 of FIGS. 2 and 4.

The essentially tubular section 36 of the housing central portion 3 is largely oval in cross section, producing niches 17 in opposed corner areas. Provided on the outside of the tubular section 36 is a cord storage device 16 for an electric power cord 21.

In operation of the appliance, the drive motor 9 is heated, causing the air in the air directing channel 12 to be heated as well. The hot air rises, by convection, in the tower-like or tubular section 36, collecting in the space 15 above the drive motor 9 and exiting through the air outlet apertures 14, as is illustrated by the arrows 18 of FIGS. 2 and 4.

By reason of the air directing channel 12 a convection air flow is maintained in the housing 3 from the air inlet apertures 13, 33 to the air outlet apertures 14 in accordance with the flow arrows 18, causing a sufficient amount of fresh, cooling air to circulate around the drive motor 9. In this arrangement, Sthe cross section of the air outlet apertures 14 is dimensioned 9 ~11~11~1_ 11_ WO 98/19585 PCT/EP97/05824 06057 such that the occurring hot air can be discharged sufficiently rapidly. The air outlet apertures 14 are disposed on the housing 1 in such a way that an operator's hand cannot reach inside the appliance.

Because of the convection air flow described in the foregoing which is caused particularly by the tubular or tower-like section 36 and the air directing channel 12 thereby formed between the drive motor 9 and the inner wall 20, it is not necessary to maintain a forced air current around the drive motor 9 using a fan wheel generally known in the art. The area of cross section of the tubular section 36 is dimensioned only so large that heat radiation also acts to radiate a heat component forming in the air directing channel 12 to the outside through the housing portion 3.

As becomes readily apparent from FIG. 3, unlike the circular cross sectional shape of the drive motor 9, the housing portion 3 is of a rhomboidal or oval configuration having corners 37, 38, so that additional storage space in the form of niches 17 is provided in the corners 37, 38, which space is able to store hot air and through which the occurring outflow directs more heat to the air outlet apertures 14 due to the stack effect.

10

Claims

1. A kitchen appliance comprising: a drive motor housing section which includes an internal chamber having an internal wall; a drive motor disposed within said chamber; a processing tool adapted to be driven by said drive motor for processing food materials; a cooling arrangement for cooling the drive motor, the cooling arrangement including one or more air inlet apertures and one or more air outlet apertures and an air directing channel between the air inlet and outlet apertures, the air directing channel being within said chamber and adjacent the drive motor, the arrangement being such that the cooling air current within the air directing channel is produced by hot air rising in the channel from the inlet to the outlet apertures.

2. A kitchen appliance according to claim 1 wherein the air directing channel is formed by a space between the drive motor and the inner wall of the chamber. 4 3* The kitchen appliance as claimed in claim 1, characterised in that the drive motor and the air directing channel extend horizontally when in use.

4. The kitchen appliance as claimed in claim 1, characterised in that the drive motor and 4. 4 the air directing channel extend generally perpendicularly to a support surface for the kitchen appliance when in use. The kitchen appliance as claimed in any preceding claim, characterised in that the air directing channel is formed by an annular chamber between the inner wall of the chamber and an outer wall of the drive motor.

6. The kitchen appliance as claimed in any preceding claim, characterised in that the P:\WPDOCS\DYS\SPECIE\716330- 16/9/99

12- housing section is a generally tubular body, the drive motor being disposed within the chamber in spaced relation to the inner wall thereof. 7. The kitchen appliance as claimed in any preceding claim, characterised in that there is a free space within the chamber between the drive motor and the air outlet apertures. 8. The kitchen appliance as claimed in any preceding claim, characterised in that the inlet apertures are disposed in a base plate so as to extend generally radially with respect to a longitudinal axis of the drive motor. 9. The kitchen appliance as claimed in claim 4, characterised in that the inlet apertures are disposed generally below the drive motor in a base plate. *4 5~ 4 The kitchen appliance as claimed in claim 4, characterised in that the housing section 15 has an asymmetrical cross section viewed normal to a longitudinal axis of the drive motor. 11. The kitchen appliance as claimed in claim 10, characterised in that the cross section of the housing section is elliptical, rhomboidal or oval. 20 12. The kitchen appliance as claimed in claim 1, characterised in that the inner wall of the housing section substantially conforms in shape to the outer contour of the drive motor.

13. The kitchen appliance as claimed in claim 1, characterised in that the surface of the housing section is dimensioned so large that of the heat taken up by the housing section as a result of the heating of the drive motor when in operation, such an amount is radiated to the environment that this amount, in combination with the hot air exiting through the outlet aperture, is sufficient to cool the drive motor adequately when in continuous duty. P:\WPDOCS\DYS\SPEC1E\71 6330 16/9/99 13

14. The kitchen appliance substantially as hereinbefore described with reference to the accompanying drawings. Dated this 16th day of September, 1999 BRAUN AKTIENGESELLSCHAFT By Its Patent Attorneys DAVIES COLLISON CAVE .0.