Electric motor-driven kitchen appliance

Abstract

 An electric motor-driven kitchen appliance (for example an immersion blender) is described which has an actuating mechanism (11; 21; 31) for adjusting the rotational speed of the motor of the kitchen appliance and for switching the kitchen appliance on and off. The kitchen appliance also has a safety device (12; 22; 32) for protecting against unintended activation of the motor.

Description

FIELD OF THE INVENTION

[0001] The disclosure concerns an electric motor-driven kitchen appliance (for example an immersion blender) which has an actuating mechanism for adjusting the rotational speed of the electric motor-driven kitchen appliance, and an on/off switch.

BACKGROUND OF THE INVENTION

[0002] Known immersion blenders satisfy the safety requirements (preventing the accidental activation) via a recessed arrangement of the on/off switch. The disadvantage of this solution for the user is the lack of operational comfort, because such a design allows for only small switch operating surfaces. Consequently the switch may only be operated with one finger, which may lead to rapid finger fatigue.

[0003] In order to avoid this disadvantage, in the Braun MRC7000 immersion blender a larger activation button that is not recessed was combined with a release device placed a certain distance therefrom, which release device must be pressed before the on/off button is activated. The operating surface of the release device includes a button borne around a horizontal axis that is arranged on the top surface of the appliance. In this solution, only the region that has a certain clearance relative to the axis of rotation is provided as an operating surface, rather than the entire top surface of the appliance. Switches that may be operated over a large surface are known from DE 34 05 652 A1, DE 10 2004 006 939 B3, DE 10 2006 056 270 B4, CH 340879 and GB 2276272 A.

[0004] From DE 358215 a drill is known that may be alternately switched on and off via a switch, wherein the switch may be operated via a trigger that is movable within a hoop guard. Electric motor-driven drills are also known, the rotational speed of which may be adjusted by the user using a slide control that is also designed as an on/off switch; see DE 41 06 119 C3. An electrical switch for activating/deactivating and regulating the rotational speed of electric motors with a switch-on lock is known from DE 199 13 712 A1.

SUMMARY OF THE INVENTION

[0005] The object of the present invention is to specify an easy-to-operate electric motor-driven kitchen appliance, the rotational speed of which may be selected by the user and which is protected against unintended activation.

[0006] This object is achieved in that the kitchen appliance is provided with an actuating mechanism (known per se) for switching the kitchen appliance on and off and for adjusting the rotational speed of the electric motor-driven kitchen appliance, and with a safety device for protection against unintended activation. The safety device makes possible an ergonomically designed actuating mechanism while complying with safety regulations.

[0007] The actuating mechanism preferably includes a button which acts on a slide control (known per se), for example, a potentiometer that is provided with an on/off switch. The actuating mechanism is preferably arranged for displaceable movement counter to a spring force within a housing of the kitchen appliance. If the button is not operated, the kitchen appliance is switched off, meaning that the rotational speed of the electric motor of the kitchen appliance is zero. If the button is pressed slightly, the electric motor is activated and runs at low rotational speed. The further the button is pressed, the higher the rotational speed of the electric motor. If the button is released again, the spring forces the button back into its starting position so that the kitchen appliance is deactivated and the electric motor stops. The actuating mechanism preferably has an operating surface that offers space for two fingers next to one another, meaning it has a length of approximately 3 to 5 (preferably 4) cm.

[0008] A first safety device for protecting against unintended activation includes a hoop guard that partially surrounds the actuating mechanism at a certain distance. The clearance between the hoop guard and the actuating mechanism is dimensioned so that a user may place at least one finger between the hoop guard and the actuating mechanism and then operate the actuating mechanism. The hoop guard and the actuating mechanism are preferably designed so that the actuating mechanism may be operated with two fingers. The hoop guard is permanently connected to the housing of the kitchen appliance, the hoop guard preferably being designed as part of the housing.

[0009] A second safety device for protecting against unintended activation includes a web that protrudes from the actuating mechanism and is permanently connected to the housing of the kitchen appliance. The actuating mechanism preferably includes a button that may be operated with two fingers and has an opening, approximately in its middle, from which the web protrudes. Thus, when the button is operated, the web is positioned between the user's fingers. If the kitchen appliance is provided with a particularly large button that, for example, has space for three fingers, this button may have two openings from each of which a web protrudes. In such case, the clearance between the two webs is designed so that a finger of the user fits between them.

[0010] A third safety device for protecting against unintended activation includes a safety button and an electrical or electronic circuit. The safety button is connected to the circuit that ensures that the kitchen appliance is switched on only if the safety button was pressed prior to activation of the actuating mechanism. Once the safety button is pressed, the actuating mechanism must preferably be activated within a specific time period in order to activate the kitchen appliance. The circuit may also be connected to a display, for example a light-emitting diode which, once the safety button is pressed, is activated for the duration of the specific time period. In this way a user may see the time period during which he must activate the actuating mechanism in order to switch on the kitchen appliance.

[0011] If the kitchen appliance is designed as an immersion blender, the safety button is preferably arranged at the upper end of the housing and the actuating mechanism is preferably arranged on the front side of the housing. Given this arrangement the safety button may, for example, be pressed with the thumb and the actuating mechanism may be pressed with multiple fingers of the same hand.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The disclosure is described in greater detail below with reference to multiple exemplary embodiments for an immersion blender as shown in the Figures, in which:

FIG. 1

shows an immersion blender in part, with a first safety device;

FIG. 2

shows an immersion blender in part, with a second safety device;

FIG. 3

shows an immersion blender in part, with a third safety device;

FIG. 4

shows a circuit for the third safety device;

FIG. 5

shows a safety button for the third safety device in the starting position;

FIG. 6

shows the safety button according to FIG. 5 in a middle depressed position;

FIG. 7

shows the safety button according to FIG. 5 in a forward depressed position; and

FIG. 8

shows the safety button according to FIG. 5 in a rearward depressed position.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The immersion blender 10 partially shown in Figure 1 has an actuating mechanism 11 and a safety device for protecting against unintended activation, which safety device includes a hoop guard 12 that partially surrounds the actuating mechanism 11 at a certain distance. The hoop guard 12 is designed as part of a housing 13. The clearance between the hoop guard 12 and the actuating mechanism 11 is dimensioned so that a user may place at least one finger between the hoop guard 12 and the actuating mechanism 11 and then operate the actuating mechanism 11, meaning that he may move the mechanism relative to the housing 13.

[0014] The immersion blender 20 partially shown in Figure 2 has an actuating mechanism 21 and a safety device for protecting against unintended activation, which safety device includes a web 22 that protrudes from the actuating mechanism 21 and is permanently connected to a housing 23 of the kitchen appliance. The actuating mechanism 21 includes a button that may be moved relative to the housing 23 and may be operated with two fingers and, approximately in its middle, has an opening from which the web 22 protrudes.

[0015] The immersion blender 30 partially shown in Figure 3 has an actuating mechanism 31 and a safety device for protecting against unintended activation, which safety device includes a safety button 32 and an electrical circuit (not shown in FIG. 3). The safety button 32 is arranged at the upper end of a housing 33 of the immersion blender, and the actuating mechanism 31 is arranged on the front side of the housing 33 of the immersion blender. The circuit ensures that activating the actuating mechanism 31 will result in the kitchen appliance being switched on, only if the safety button 32 was pressed beforehand. The circuit will preferably activate the kitchen appliance only if, once the safety button 32 has been pressed, the actuating mechanism 31 has been activated within a specific time period.

[0016] An electronic circuit that is suitable for the kitchen appliance according to FIG. 3 is shown schematically in FIG. 4. The circuit has a key button 7 that may be activated by the safety button 32 and is connected to a controller C. The controller C is supplied by a power supply X (preferably with potential separation) from an electric mains represented by terminals L, N. Connected in series between the terminals L and N are the motor M of the kitchen appliance, a slide control S and an electronic switch E. The electronic switch E is connected to the controller C via a coupler K (preferably an optocoupler). The slide control S has an on/off switch and a signal emitter G that is connected to the controller C. The slide control S may be activated by the actuating mechanism (schematically represented by an arrow in FIG. 4). Connected to the controller C is a display D, for example a light-emitting diode.

[0017] The function of the electronic circuit is described in the following. The key button 7 is activated by pressing the safety button 32. This results in the controller C activating the display D for the duration of the specific time period. If the user activates the actuating mechanism 31 (schematically represented by an arrow in FIG. 4) that acts on the slide control S within the specific time period, the on/off switch is closed and the controller C detects a signal at the signal emitter G. The controller C thereupon activates the motor M by actuating the electronic switch E via the coupler K. The signal at the signal emitter G is a function of how far the user moves the slide control out of its starting position. The controller C correspondingly generates a control signal for the electronic switch E, which control signal determines the rotational speed of the motor. The electronic switch E may, for example, have a triac that is controlled by the controller C in the manner of a phase angle control. If the user does not activate the actuating mechanism 31 within the specific time period, the motor M is not activated by the controller C, even though the on/off switch of the slide control S is closed.

[0018] The safety button 32 shown in Figures 5 - 8 is particularly easy to operate because it is mounted so that its entire surface serves as an operating surface 1. This mounting includes a combination of a ball bearing guide and a linear guide. The safety button 32 has a spherical segment 2 permanently connected to the operating surface 1, which spherical segment 2 is directed in a cylindrical bushing 3 formed in the housing 4 of the kitchen appliance. This allows for virtually clearance-free linear movement of the safety button along the inner surface of the bushing 3, with concomitant rotational movement around the center Z of the spherical segment 2. Together with the lower edge of the bushing 3, a peripheral collar 5 located at the lower end of the spherical segment 2 forms an upper boundary of the linear movement and an angular boundary of the rotational movement. The safety button 32, after being released, is returned to its initial position again by means of at least one return spring 8. The safety button 32 has an approximately centrally placed element 6 for activating the key button 7, which element 6 is preferably resilient in design and, for example, made of a steel spring or an integrated plastic spring, whereby the force acting on the key button 7 is limited and the key button 7 is protected against overloading.

[0019] The functionality of the safety button 32 mounted in such a manner is explained as follows: Activating the center of the operating surface 1 causes a largely linear downward movement of the safety button 32 along the inner surface of the bushing 3, thus activating the key button 7 (see FIG. 6). Activating an arbitrary point outside of the center of the operating surface 1 results in a tilting motion of the safety button 32. The motion occurs around a contact point 9 that lies between the peripheral collar 5 and the lower edge of the bushing 3, opposite the activation point relative to the center Z. This tilting motion includes the superimposition of a linear motion along the cylindrical bushing 3 and a rotational movement around the center Z, causing the element 6 to lower, thereby activating the key button 7 (see FIG. 7, 8).

[0020] In a different embodiment of a kitchen appliance (not shown in the Figures), the circuit additionally has a temperature sensor with which the temperature of the motor M is monitored. If the temperature of the motor rises above a specific value -- for example given an extreme loading or even a blocked motor -- the circuit deactivates the motor and activates a warning indicator, for example a red light-emitting diode. The circuit may also be designed so that a display, for example, a red blinking light-emitting diode, indicates a connection between the kitchen appliance and the electric mains.

[0021] An additional safety device for protecting against unintended activation includes a mechanical locking device (known per se). The locking device ensures that the kitchen appliance may be activated only if a safety button was pressed prior to activation of the actuating mechanism. Namely, the actuating mechanism is unlocked by pressing the safety button. The locking device preferably locks the actuating mechanism automatically (via spring pressure, for example) after the actuating mechanism is released. The safety button also returns preferably automatically (via spring pressure, for example) to its initial position. The kitchen appliances shown in Figures 1 through 3 may also be provided with the mechanical locking device, in addition to the respective present safety device.

[0022] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

Claims

1. An electric motor-driven kitchen appliance, for example an immersion blender, having a housing and an actuating mechanism for adjusting the rotational speed of the motor of the kitchen appliance and for switching the kitchen appliance on and off, and having a safety device for protecting against unintended activation of the motor.

2. The electric motor-driven kitchen appliance according to Claim 1, characterized in that the actuating mechanism (11; 21; 31) is a button which, when activated, acts on a slide control, which slide control has an on/off switch and a signal emitter for rotational speed adjustment.

3. The electric motor-driven kitchen appliance according to Claim 1 or 2, characterized in that the safety device has a safety button (32) separate from the actuating mechanism (31) and an electrical or electronic circuit.

4. The electric motor-driven kitchen appliance according to Claim 3, characterized in that the circuit is connected with the signal emitter (G) and has a key button (7) that may be actuated by the safety button (32).

5. The electric motor-driven kitchen appliance according to Claim 4, characterized in that the circuit has a controller (C) for controlling the motor (M), wherein the controller (C) activates the motor (M) only if the slide control (S) is operated following actuation of the key button (7).

6. The electric motor-driven kitchen appliance according to Claim 5, characterized in that the controller (C) activates the motor (M) only if the slide control (S) is operated within a specific time period following actuation of the key button (7).

7. The electric motor-driven kitchen appliance according to Claim 6, characterized in that the controller (C) is connected to a display (D), and in that the controller (C) activates the display (D) during the specific time period.

8. The electric motor-driven kitchen appliance according to any one of the Claims 3 to 7, characterized in that the circuit has a temperature sensor for measuring the temperature of the motor (M), and activates a warning indicator if the temperature is too high.

9. The electric motor-driven kitchen appliance according to any one of the Claims 3 to 8, characterized in that the circuit has a display that indicates a connection between the kitchen appliance and the electric mains.

10. The electric motor-driven kitchen appliance according to any one of the Claims 3 to 9, characterized in that the safety button (32) has a spherical segment (2) that is displaceably and tiltably guided in a cylindrical bushing (3) formed in a housing (4; 33).

11. The electric motor-driven kitchen appliance according to Claim 10, characterized in that the safety button (32) has a peripheral collar (5) and the cylindrical bushing (3) has a lower edge that restricts the movement of the safety button (32).

12. The electric motor-driven kitchen appliance according to any one of the Claims 1 to 2, characterized in that the safety device is a hoop guard (12) that is connected to the housing (13) and is arranged in front of the actuating mechanism (11).

13. The electric motor-driven kitchen appliance according to any one of the Claims 1 to 2, characterized in that the safety device is a web (22) that is connected to the housing (23), and in that the actuating mechanism (21) has an opening from which the web (22) protrudes.

14. The electric motor-driven kitchen appliance according to any one of the preceding claims, characterized in that it has a mechanical locking device for locking the actuating mechanism (11; 21; 31).

15. The electric motor-driven kitchen appliance according to Claim 14, characterized in that the mechanical locking device has a safety button for unlocking the actuating mechanism (11; 21; 31).

Drawing