DE102010040497B4 - Electric motor driven household appliance and control method - Google Patents

Abstract

Domestic appliance (1) having at least one rotatably and / or translationally movable tool and an electric motor drive (M), wherein the household appliance (1) means for detecting the load state of the tool, which are provided for determining a rotational speed (n) of the tool, and a control device (SE), which is suitable for changing the power (P) of the electric motor drive (M) in dependence on the measured load condition, characterized in that the control device (SE) is adapted to the power (P) of the electric motor drive (M) increase as soon as the speed gradient (Δn / Δt) of the tool reaches a predetermined threshold.

Description

Background of the invention

The invention relates to a household appliance with at least one rotatably and / or translationally movable tool and an electric motor drive, wherein the household appliance has means for detecting the load state of the tool and a control device which is suitable for changing the power of the electromotive drive in dependence on the measured load condition , And a method for operating a household appliance with at least one electric motor driven tool. In this case, the means for detecting the load state of the tool for determining a rotational speed of the tool or a current consumption of the electromotive drive are provided.

State of the art

A generic household appliance in the form of a food processor is known from the German patent DE 44 22 086 C1 known. The device described therein is equipped with a device for detecting the speed of the kitchen tool and for controlling the speed to a set target value. As a result, a simple speed control is provided, which keeps the speed of the kitchen tool, regardless of the load constant. Another example of a generic household appliance is in DE 35 35 939 C2 disclosed.

From such household appliances may result in improper use hazards. It can not be ruled out in abusive handling that the user gets in contact with the outside of the material to be treated only from above through the foot part hidden tool. In addition, especially when editing hot, liquid Behandlungsguts when starting the device, if necessary, a squirting out of the receptacle occur.

In the publication DE 603 17 091 T2 discloses another electric motor driven food processing apparatus, in which an evaluation of the feedback signal of an actuator is provided by a control unit. The control unit may adjust the current provided to the motor based on the feedback signal. A scheme suitable for solving the aforementioned problem also does not have this device.

A trained as a hand blender home appliance is in the utility model DE 89 03 799 U1 disclosed. The stirrer has a cylindrically shaped, usually injection molded from plastic handle from which coaxially protrudes a shaft shaft. The shaft shaft is equipped at its free end with a bell-shaped foot part pointing away from the shaft shaft into which a tool for the touching or cutting treatment of material to be treated, for example dough, vegetables or the like, can be used. If necessary, the tool is rotated by a drive shaft arranged in the shaft shaft. The shaft shaft is in turn connected to an electric motor drive device.

It is known to provide arranged as a drive device in the handle electronic or two-stage engines whose speed slows down under load, especially when processing heavy dough or the like. Alternatively, it is proposed to pass through the handle a flexible shaft, which is in rotation with a located outside the handle, controllable and air-cooled electric motor. Through this spatial separation of household appliance and electric motor drive and a long-lasting processing of hot or boiling good, for example in the preparation of jam should be possible.

From the utility model DE 93 01 408 U1 It is known to provide a hand mixer with a clear foil consisting of splash guard, which has in the middle recesses for the implementation of the stirring and edge rests on the receptacle. A sufficient air supply should be ensured by air holes in the cling film. Such a device can be uncomfortable in terms of handling and it can not prevent touching the tools in case of unintentional switching on the device before applying the splash guard.

In the patent DE 100 33 032 C1 is described a tool shielding footboard for a hand blender, which is formed like a wave at its lower edge and equipped on its lateral surfaces with outflow openings. By this design, unintentional spraying should be avoided by ejected out of the receptacle material to be treated and a fixed eyes of the hand blender at the bottom of the treatment vessel. A contact with the tool located outside of the material to be treated by accidental actuation of the hand blender this training also can not be prevented.

In the layout DE 29 04 159 B1 discloses an electric handset for the selective use of stirring or cutting tools, in which a tool scanning a circuit is excluded to continuous operation, as soon as Cutting tool is inserted into the handset. This safety mechanism may reduce the amount of time the user inadvertently touches the cutting tool.

From the utility model DE 83 22 822 U1 It is also known to improve the safety of electric motor-driven household appliances by an on / off switch with an additional switch-lock, which must be solved before switching on the device. This makes it difficult or even completely impossible for the device to be switched on by children or accidentally switched on, for example when cleaning the device.

In the published patent application DE 41 34 025 A1 a mobile mixing device with a pivotally mounted, rotary driven agitator is described with downwardly projecting, rod-shaped stirring arms, which are introduced before receiving the stirring process from above into the mix in the receiving vessel. Two safety switches ensure that it is only possible to operate the mixer with the receptacle inserted and the stirrer swiveled in. However, such a circuit can be difficult to implement in hand-held household appliances.

The problem underlying the invention

The invention has for its object to further improve a generic household appliance in terms of the likelihood of injury from rotating tools and with respect to the likelihood of spillage of items to be treated.

Inventive solution

The object underlying the invention is achieved by a household appliance according to claim 1 or 2 and by a method for operating a household appliance according to claim 8 or 9. According to the invention, the control device in a generic domestic appliance is set up to increase the power of the electromotive drive as soon as the time gradient of the rotational speed of the power train or the time gradient of the current consumption of the electromotive drive reaches a predetermined threshold value. In the method according to the invention for operating a household appliance with at least one electromotive-operated tool, the power of the electromotive drive is increased as soon as the time gradient of the rotational speed of the tool or the temporal gradient of the current consumption of the electromotive drive reaches a predetermined threshold value.

It is an achievable advantage of the invention that the user can get in abusive use of the household appliance only with a low power ("Hibernate Mode") operated tool in touch, so that the risk of injury is significantly reduced. In addition, the likelihood of ejection of material to be treated from the receptacle is significantly reduced, should an already moving tool be introduced into the material to be treated. Nevertheless, after immersing the tool in the material to be treated, sufficient power is available ("power mode").

The invention can be used with particular advantage in household appliances with rotating tools, for example in hand blenders, hand mixers or bread slicers. The household appliance can have individual or multiple tools arranged. However, a successful application is basically also in household appliances with translationally moving tools, such as electric knives conceivable.

Preferred embodiment of the invention

Advantageous embodiments or developments, which can be used individually or in combination with each other, are the subject of the dependent claims.

According to one aspect of the invention, the means for detecting the loading state of the tool are preferably provided for determining the rotational speed of the tool or changing it. In case of accidental contact with the low-power tool, a significant change in the speed is not expected. However, if the tool is introduced into the material to be treated, the speed of the tool drops significantly as a result of the suddenly increased resistance. The detection of the rotational speed of the tool can for example be done by an optical or magnetic mark on the shaft of the drive shaft or the electric motor, which generates an electrical pulse when passing a corresponding sensor. From the temporal sequence of the pulses then the speed of the tool can be calculated.

In a particularly simple manner, however, the detection of the load state of the tool can be effected by providing means for determining the current consumption of the electromotive drive or changing it. The measurement of power consumption can be realized with simple electronic components and possibly already in Provided under overload shutdown in the household appliance.

Furthermore, it is preferably provided that the household appliance is additionally equipped with a safety switch-on of at least two switching elements, which are to be switched to turn on the household appliance in a switch-on. As a result, not only the possible effects, but also the likelihood of an unwanted turn on the household appliance are reduced. By a suitable spatial arrangement of the handling of the switching elements or the required switching sequence can be avoided that an unintentional actuation of both switching elements takes place.

It can be advantageously provided that the switching elements are electrically connected to the electric motor drive. This can be done in a simple manner by a series connection of switching elements in the power supply to the electric motor drive, so that a current flow and startup of the household appliance only take place when both switching elements are simultaneously in the on position.

Alternatively, it may be provided that the switching elements are electrically operatively connected to one another mechanically and at least one switching element is electrically connected to the electromotive drive. This can be done in a simple manner and space-saving manner by a simple mechanical locking of a switching element, which is suitable for interrupting the power supply to the electric motor drive.

The domestic appliance according to the invention is furthermore advantageously equipped with means which are provided for emitting an acoustic signal as a function of the load condition of the tool. As a result, the user is advised that the tool of the household appliance is already in motion, but the load condition suggests that the tool is not or not completely immersed in the material to be treated and thus unwanted contact of the user is not excluded with the tool , Alternatively or additionally, means for emitting an optical signal may be provided depending on the loading condition of the tool. As a result, the security of the household appliance is further improved.

According to a further aspect of the invention, a preferred method for operating the household appliance is characterized in that the speed of the tool detected and the power of the electric motor drive is increased as soon as the speed of the tool reaches a predetermined threshold and in particular falls below a limit speed. Such a procedure is particularly easy to implement in terms of control engineering.

With particular advantage may also be provided that the speed of the tool detected and the power of the electric motor drive is increased when the speed gradient of the tool reaches a predetermined threshold. This procedure allows a particularly sensitive switching from low power ("Hibernate Mode") to high power ("Power Mode").

Furthermore, it is preferred that the current consumption of the electric motor drive detected and the power of the electric motor drive is increased when the current consumption of the electric motor drive reaches a predetermined threshold. In this case, the detection of the load condition can be done by optionally existing electronic components of the household appliance and its electric motor drive.

Advantageously, the method is further designed to the effect that the current consumption of the electric motor drive detected and the power of the electric motor drive is increased when the gradient of the current consumption of the electric motor drive reaches a predetermined threshold. This approach also allows a particularly sensitive power control.

The preferred methods mentioned will as a rule be selected as an alternative. However, it is generally not excluded to combine them with each other. Particularly advantageous is a method for operating a household appliance with electric motor-operated tools, in which detects the load condition of the tool and the power of the electric motor drive is reduced as soon as the measured load condition leaves the predetermined threshold. As a result, the benefits of the invention come not only before immersing the tool in the material to be treated, but also when pulling out the still moving tool from the treated to bear.

Brief description of the figures

The invention is explained in more detail below with reference to schematic drawings of two exemplary embodiments with further details.

Show it:

1 : the procedure on a first household appliance according to the invention;

2 : the procedure according to another embodiment of the invention.

Detailed description of the invention with reference to two embodiments

This in 1 illustrated household appliance 1 is as a stick mixer 2 formed and consists of a handle 3 , one of this projecting wave shaft 4 and a formed on this footboard 5 , handle 3 , Wave shaft 4 and foot part 5 are one or more pieces as injection molded parts made of easy-care plastic. The foot part 5 has the shape of a bell open at the bottom and receives a rotating stirring or cutting tool (arrow 6 ), which rotatably on the projecting end of a shaft shaft 4 guided wave can be placed. The other end of the shaft is connected to an electric motor drive M, which is in the handle 3 is arranged and via a power cord 7 can be connected to a standard 230 V AC mains. Alternatively, a power supply by a handle 3 arranged accumulator possible. In the handle 3 there is also a safety switch-on 8th with a first switching element 9 and a second switching element 10 in series in the power supply 11 to the electric motor drive M are arranged. The switching elements 9 . 10 Can handle the safety switch on 8th , For example, via push buttons, are operated independently.

Because the bell-shaped foot part 5 the example, knife-like trained tool only covered from above and to the side, can not be excluded in principle that the user of the household appliance or a person in the vicinity touch the tool. Unless the tool is in motion, this contact is usually unproblematic. After immersion of the tool in the material to be treated, this also does not constitute a source of danger. However, contact with a tool rotating freely outside the material to be treated at full power is absolutely to be avoided. Furthermore, a tool rotating at full power after being pulled out of the material to be treated, in particular if it is hot, can be safety-critical by producing splashes even without direct contact with the tool.

To the household appliance 1 To be put into operation, are initially provided as a simple on / off switch (on / off) switching element 9 as well as serving as an additional security button switching element 10 simultaneously to operate (arrow 12 . 12 ' ). The electric motor drive M of the household appliance 1 Goes from the start phase in a phase of low power output (see diagram: power P over time t), in which the quasi-resistance rotating before dipping into the treated material rotating tool with a relatively high speed n (see diagram speed n over time t) , Because of the low power output of the electromotive drive M in conjunction with the low mass of the tool in this state when touched no significant source of danger. To further reduce the remaining risk to the user, this operating state by an audible and / or visual signal (possibly also by a tactile signal, for example by vibrations) communicated to the user and his environment.

When the tool is immersed in the material to be treated, the rotational speed n, which characterizes the load condition of the tool and which is measured via sensors, suddenly drops (arrow 13 ). The calculated speed gradient or falling below a predetermined threshold (limit speed) cause the control device ("Smart Electronic (SE)") of the household appliance 1 to (arrow 14 ), To raise the power of the electric motor drive considerably, so that a treatment of the material to be treated is made possible. When pulling out the tool 5 From the material to be treated, the sudden increase in rotational speed n, not shown, serves as an indication of the relief of the tool. The control of the household appliance 1 in this case regulates the power of the electromotive drive M back to a low value.

An alternative method of operating the household appliance 1 is in 2 shown, with the basic structure of the hand blender 2 does not differ from the previously described embodiment. Instead of sensors for determining the rotational speed n, however, means for determining the current consumption of the electromotive drive M are provided in this case. With the immersion of the tool in the material to be treated, the absorbed current I increases significantly (see arrow 15 to the diagram: current I over time t). The calculated gradient of the current consumption or the exceeding of a fixed threshold (limit current consumption) cause the control of the household appliance 1 to (arrow 16 ) to increase the power of the electric motor drive M to provide sufficient torque for the treatment of the material to be treated. The means for determining the current consumption can also serve to switch off when exceeding a further, higher limit (overload current), the electric motor drive M, for example, to avoid damage to the household appliance when blocking the tool.

The features disclosed in the foregoing description, the claims and the drawings may be of importance both individually and in any combination for the realization of the invention in its various forms.

LIST OF REFERENCE NUMBERS

1

household appliance

2

Hand blender

3

handle

4

spindle shaft

5

footboard

6

Arrow (direction of rotation of rotating tool)

7

power cable

8th

Safety switch-

9

switching element

10

switching element

11

power supply

12, 12 '

Arrow (effect of the operated safety switch-on device)

13

Arrow (effect of machining resistance on the speed n)

14

Arrow (control of power P as a function of speed n)

15

Arrow (effect of machining resistance on absorbed current I)

16

Arrow (control of the power P as a function of the absorbed current I)

I

electricity

M

electric motor drive

n

rotation speed

P

power

t

Time

SE

control device

Claims (9)

Household appliance ( 1 ) with at least one rotatably and / or translationally movable tool and an electric motor drive (M), wherein the household appliance ( 1 ) Means for detecting the load state of the tool, which are provided for determining a rotational speed (n) of the tool, and a control device (SE) suitable for varying the power (P) of the electric motor drive (M) in dependence on the measured load condition is, characterized in that the control device (SE) is adapted to increase the power (P) of the electric motor drive (M) as soon as the speed gradient (Δn / Δt) of the tool reaches a predetermined threshold. Household appliance ( 1 ) with at least one rotatably and / or translationally movable tool and an electric motor drive (M), wherein the household appliance ( 1 ) Means for detecting the load state of the tool, which are provided for determining a current consumption (current I) of the electric motor drive (M), and a control device (SE), which for changing the power (P) of the electric motor drive (M) in Depending on the measured load condition is suitable, characterized in that the control device (SE) is adapted to increase the power (P) of the electric motor drive (M) as soon as the time gradient (.DELTA.l / .DELTA.t) of the current consumption of the electric motor drive (M ) reaches a predetermined threshold. Domestic appliance according to one of the preceding claims, characterized in that the domestic appliance ( 1 ) with a safety switch-on device ( 8th ) of at least two switching elements ( 9 . 10 ), which is used to switch on the household appliance ( 1 ) are to be adjusted to a switch-on. Domestic appliance according to claim 3, characterized in that the switching elements ( 9 . 10 ) are electrically connected to the electric motor drive (M). Domestic appliance according to claim 3, characterized in that the switching elements ( 9 . 10 ) mechanically with each other and at least one switching element ( 10 ) are electrically operatively connected to the electric motor drive (M). Domestic appliance according to one of the preceding claims, characterized in that means are provided for emitting an acoustic signal in dependence on the load condition of the tool. Domestic appliance according to one of the preceding claims, characterized in that means are provided for emitting an optical signal in dependence on the loading state of the tool. Method for operating a household appliance ( 1 ) with at least one electric motor driven tool, wherein the load condition of the tool is detected by a speed (n) of the tool is detected, characterized in that the power (P) of the electric motor drive (M) is increased as soon as the speed gradient (Δn / Δt) of the tool reaches a predetermined threshold. Method for operating a household appliance ( 1 ) with at least one electric motor drivable tool, wherein the load condition of the tool is detected by a current consumption (current I) of the electric motor drive (M) is detected, characterized in that the power (P) of the electric motor drive (M) is increased, as soon as the time gradient (.DELTA.l / .DELTA.t) of the current consumption of the electric motor drive (M) reaches a predetermined threshold.

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