Food processor

A food processor is known which comprises a base unit (1, 6) having at least two separate mounts (2, 3) for one processing container (4, 5) each. A respective rotary drive shaft is disposed in the area of each mount (2, 3), which drive shaft is adapted to drive a processing tool (9) insertable into the processing container (4, 5) for the processing of food materials. The drive shafts are connected to an electric motor (29) by a transmission mechanism. A switch device (S1) is provided downstream from and in series with a manually actuatable main switch (8; S3) to enable electric current to be released to the motor (29), said switch device being adapted to be turned on or off by movement of a lid (10, 11) which closes or opens the respective processing container (2, 3), such that an actuating element (13, 14) formed on the lid (10, 11) displaces a lever arrangement (15) connected with the switch device (S1) in such fashion as to cause actuation of a switching contact (23). In order to achieve a simple design for such a switch device which serves as a safety device, a common motor switching contact (23) for releasing electric current to the motor (29) is assigned to the lids (10, 11). According to the present invention, this motor switching contact (23) is actuated by a lever arrangement (15) mounted in the housing (6) and comprising two sections (16, 17).

This invention relates to a food processor, comprising a base unit having 
at least two separate mounts for one processing container each, with a 
respective rotary drive shaft being disposed in the area of each mount, 
which drive shaft is adapted to drive a processing tool insertable into 
the processing container for the processing of food materials, said drive 
shafts being connected to an electric motor by a transmission mechanism, 
and with a switch device being provided downstream from and in series with 
a manually actuatable main switch to enable electric current to be 
released to the motor, said switch device being adapted to be turned on or 
off by movement of a lid which closes or opens the respective processing 
container, such that an actuating element formed on the lid displaces a 
lever arrangement connected with the switch device in such fashion as to 
cause actuation of a switching contact. 
A food processor of the type indicated in the foregoing is known from DE-C 
39 33 036. Such a food processor which is also referred to as a 
multi-purpose food processor finds application wherever a variety of tasks 
are to be performed such as, for example, kneading, mixing and beating. To 
make such a food processor flexible, two processing containers--the large 
one being used for mixing, comminuting, kneading, the small one for 
blending or comminuting--are provided which are each associated with a 
separate drive spindle. A motor disposed in a base unit drives these two 
spindles at different speeds due to the provision of a different 
transmission ratio of the drive shaft and the motor to the respective 
drive spindle. 
For safety reasons the processing containers of the food processor of the 
type described in the foregoing are locked in predetermined positions in 
the base unit in order to establish a reliable driving connection between 
the processing container and the base unit and to ensure that the 
processing container remains connected with the base unit during 
operation, particularly at instants of time when a certain unbalance 
produced by a distribution of the food materials to be processed occurs in 
the container. A further safety provision necessary for such food 
processors is that the motor is prevented from running until the lid 
placed on the processing container is securely locked therewith, thus 
making it impossible for the user to reach inside the container with the 
lid open and have access to the rotating processing tool such as, for 
example, a mixing or cutting tool. Any attempt to open such a lid or any 
direct removal of the lid turns off the motor instantly. 
With regard to the safety provision indicated in the foregoing which 
relates to the opening of a lid of the processing container while the 
motor is running, DE-C2 39 33 036 makes provision for a separate switch 
for each processing container or its associated lid, whose switching 
contact is placed in the current path to the motor. When the respective 
switch associated with the one or the other lid of the respective 
processing container is actuated, the current path is either interrupted 
(lid removed from the processing container) or closed (lid seated onto the 
processing container). Each switching contact possesses a lever-type pin 
that engages in an actuating cam formed on the respective processing 
container. The safety device described above has proven to be successful 
and efficient in practical use. 
On the basis of the prior art referred to in the foregoing, it is an object 
of the present invention to improve upon a safety device of the described 
type in such manner that it is of simple construction and that, in 
addition, these switching functions are coupled in respect of the lid of 
the one processing container and the lid of the other processing 
container. 
On the basis of the known food processor initially described, this object 
is accomplished in that the lids are assigned a common motor switching 
contact for the release of electric current to the motor, and that this 
motor switching contact is actuatable by a lever arrangement mounted in 
the housing and comprising two sections, with the position of the lever 
arrangement relative to the position of the lids of the processing 
containers being oriented such that the one section of the lever 
arrangement is actuatable by the actuating element of the one lid, while 
the other section of the lever arrangement is actuatable by the actuating 
element of the other lid. 
With the arrangement of the present invention, only one single switch is 
needed which in respect of its switching function is associated with both 
the one lid and the other lid of the at least two processing containers 
through a corresponding lever arrangement. 
In the configuration of the present invention, the one switch associated 
with both lids of the processing containers is pivoted by the respective 
lid when it is fitted onto the processing container in a predetermined 
direction, such that starting from an initial position in which the 
switching contact is open and no current is supplied to the motor, the 
switching contact is closed; the current path to the motor is then closed 
enabling the appliance to be turned on by actuation of an appliance main 
switch. The arrangement manages not only with one single switch but also 
with one single lever arrangement for actuation of the switch, for which 
purpose the lever arrangement is subdivided into two sections which are 
associated with the one and the other lid provided that the food processor 
has only two processing containers and respective lids. 
According to a preferred aspect the lever arrangement is assigned a neutral 
initial position to which it returns following a reversal of the direction 
of movement of a lid, that is, starting from a contact making position. In 
such an initial position the lever arrangement is oriented such as to be 
actuatable by the one or the other lid, depending on which processing 
container is to be used, in order to move the switch to its contact making 
position, which then enables the motor to be turned on by a main switch. 
The automatic return to the initial position is accomplished by a spring 
acting on the lever arrangement. 
The movement of the lever arrangement back into the initial position is 
effected by the movement of the lid or is at least initiated by the 
movement of the lid to its release position, meaning that not only does 
the respective lid move the lever arrangement into the contact making 
position but it also returns it to the initial position when this 
particular lid is moved to the release position. 
For defined closing of the current path by means of the switch associated 
with the lever arrangement, it is desirable that the lever arrangement 
include at least one control cam that opens or closes the motor switching 
contact of the switch. This control cam may be configured in respect of 
the rotary or pivotal movement of the lever arrangement such that the 
motor switching contact is prevented from closing until the lid actuating 
the lever arrangement occupies a closed position in which it is securely 
held or locked on the processing container without enabling further 
manipulation by the user. 
Each lid should have a pin-type protrusion engaging in the associated lever 
arm or in a section of the lever arrangement. With such a pin-type 
protrusion it can be ensured that the lever arrangement is actuatable--for 
closing the motor switching contact--only when the lid is properly 
positioned on the processing container and moved to its locked position, 
because otherwise, that is, with the lid improperly fitted to the 
processing container, the pin-type protrusion of the lid is prevented from 
engaging the lever arrangement. 
In addition, for a defined engagement of the pin-type protrusion with the 
lever arm, a fork or claw shaped section may be formed at the end of each 
lever arm; such an end section could be dimensioned such that the tines or 
claws engage the pin-type protrusion on either side when in the contact 
making position, causing the lever arm and the pin to be in relative 
engagement and to be prevented from disengagement, even when an external 
force is applied, unless the lid is again moved to its release position 
according to proper procedure. Still further, it is preferable for the 
tine of the fork or the claw member producing the contact making position 
to be of greater length than the other tine of the fork or claw member, 
resulting in sufficient clearance space for the pin to disengage itself 
from the tines or claws of the lever arm in the release position, while on 
the other hand in the operating position the pin securely engages the 
lever arm as mentioned previously, keeping the lever arm in the closed 
position for the motor switching contact. 
Particularly when only small amounts of, or thin-liquid, food materials 
have been processed in the processing container it may happen that the 
motor continues to rotate for a long period after shut-off and/or after 
opening of the lid and hence the return of the lever arrangement. In such 
an event there would be the risk that the processing tool, for example, a 
cutting tool, continues to rotate when the user removes the lid from the 
processing container immediately thereafter. To eliminate such a risk, it 
is preferable to provide a motor braking current switching contact. This 
motor braking current switching contact is equally associated with the 
lever arrangement and actuated by the movement of the lever arrangement. 
Such a motor braking current switching contact is closed when the lever 
arrangement is in the initial position. The switching contact releases a 
braking current in the motor winding which then acts against the motor 
rotation, braking the motor. As a result, the processing tool rotating in 
the processing container comes to a halt speedily. To initiate the braking 
of the motor rotation at a very early instant of time, the motor braking 
current switching contact is closed immediately after the motor switching 
contact opens. 
To make sure that the lever arrangement returns to its initial position 
also when, for any reason, it should be pivoted into the operating 
position in which the motor switching contact is closed, the switching 
contact should be configured as a spring such as to support the returning 
of the lever arrangement into the initial position. Additionally however, 
a spring element may be fitted to the lever arrangement as mentioned 
previously, which supports this returning of the lever arrangement into 
the initial position.

The food processor of the type illustrated in FIG. 1 has a base unit 1 with 
two mounts 2, 3 each for one processing container 4, 5. In the rear 
housing area between the two mounts 2, 3 or the respective processing 
containers 4, 5, a tower-like housing 6 extends from the base unit 1 
upwardly. Among other purposes, this tower-like housing 6 may serve to 
accommodate an electric motor. 
Two rotary switches 8 are disposed on a front sloping control panel 7, one 
switch operating as a main switch for turning the electric motor on or off 
by hand. 
Processing tools 9 of different configurations are fitted to a drive 
spindle, not shown in greater detail, in the respective containers 4, 5, 
said spindle being in driving connection with an electric motor (not 
shown) by means of a drive train disposed in the lower housing unit 1. 
To process food materials with the food processor shown, the left-hand 
processing container 4 or the right-hand processing container 5 is placed 
on its assigned mount 2 or 3. The two processing containers 4, 5 differ in 
capacity, and in addition, their processing tools 9 may have their speeds 
reduced or increased with respect to the motor speed, depending on the 
work needing to be performed. 
The container 4, 5 is then locked in its respective mount 2, 3 and closed 
with a respective lid 10, 11. Independent of the associated container 4, 
5, the respective lid 10, 11 is rotated into a locked position according 
to the direction of rotation of the respective arrows 12. Rotation of the 
lid 10 or 11 may also take place together with the processing container 4 
or 5 in case the processing container 4, 5 is placed into its respective 
mount 2, 3 with a lid 10, 11 already locked in place. 
As illustrated in FIG. 1 and in greater detail in FIG. 2, each lid 10, 11 
carries at a defined location in its outer peripheral area a vertically 
upwardly protruding pin 13, 14. These two pins 13, 14 are associated with 
a lever arrangement generally identified by reference numeral 15. The 
lever arrangement 15 comprises two sections in the form of two lever arms 
16, 17 having their longitudinal dimensions oriented a defined angle 18. 
The lever arrangement 15 is pivotal about a pivot axis 19 in the direction 
of the double arrow 20. Furthermore, a cam disk 21 is fixedly secured to 
the lever arms 16, 17 in the area of the pivot axis 19, that is, the cam 
disk occupies a predefined position relative to the two lever arms 16, 17. 
Two control cams 22 are formed on the cam disk 21, whereof the one control 
cam 22, in FIG. 2 the upper one, is associated with a motor switching 
contact 23, while the lower control cam 22 is associated with a motor 
braking current switching contact 24. By rotation of the lever arrangement 
15 and hence of the cam disk 21 in the direction of the double arrow 20, 
the two control cams 22 engage each with switching contact projections 25, 
causing the respective switching contact 23 or 24 to be moved to the 
effect that a switch S1 for the motor operating current is closed and a 
switch S2 for a motor braking current is opened. 
The mode of operation of the safety device formed by the aforedescribed 
structure comprising the lever arrangement 15 as an essential component is 
as follows: 
The two lever arms 16, 17 are dimensioned and configured such as to move 
from an initial position illustrated in FIG. 2 into engagement with the 
pin 13 and 14, respectively. To this effect, a claw 26 is formed at the 
end of each lever arm 16, 17. As seen in the direction of rotation, a 
rearward longer claw member 27 ensures that the respective pin 13 and 14 
reliably engages within the claw 26 in the closing direction. Proceeding 
from the initial position illustrated in FIG. 2, upon further rotation of 
the respective lid 10, 11 in the direction of the arrow 12 the respective 
lever arm 16, 17 is pivoted and the cam disk 21 is rotated in the 
clockwise direction. 
With the lid 10, 11 in an end position, the switch S1 is closed and the 
switch S2 is opened. Closing of the switch S1 causes closing of the one 
current path from the power source 28 to the motor 29, so that when the 
switch S3 incorporated in one of the rotary switches 8 illustrated in FIG. 
1 is closed, power is supplied to the motor 29 which then starts running. 
In the event that the lid 10 or 11, which has been moved into engagement 
with the corresponding lever arm 16 or 17 and has closed the switch S1, is 
unlocked again from its locked position while the appliance is in 
operation, the respective lever arm 16 or 17 is pivoted by the pin 13 or 
14 in counterclockwise direction, causing the cam disk 21 to rotate in 
clockwise direction. The cam 22 is then moved out of its engagement with 
the switching contact projection 25, causing the switch Si to be opened 
and hence the supply of power to the motor 29 to be interrupted. 
At the same time, rotation of the cam disk 21 in clockwise direction causes 
the lower control cam 22 to be moved out of engagement with the switching 
contact projection 25 of the motor braking current switching contact and 
to open the switch S2 which closes a circuit--indicated by the two lines 
30--to the motor 29, in order to brake the motor. In the initial position, 
the food processor is then not operable because the switch S1 is open, 
operation being prevented also when the switch S3, that is, the main 
switch, is closed. 
While in FIG. 2 the lids 10, 11 of the two processing containers 4, 5 are 
illustrated schematically to make it clear that the respective pins 13, 14 
are associated with the lever arms 16, 17 of the lever arrangement 15 and 
adapted to engage within the claws 26, it will be understood that 
conventionally provisions are made according to which either only the 
left-hand processing container 4 or only the right-hand processing 
container 5 can be placed on the base unit 1 for operation. 
As becomes apparent from FIG. 1, the lever arrangement 15 is arranged at 
the upper end of the tower-like housing 6 beneath a housing lid 31, and 
the end sections of the lever arms 16, 17, that is, the two claws 26, 
protrude from slots, not shown in greater detail, in order to be able to 
engage with the pins 13, 14 of the lids 10, 11. 
As will be recognized from the preceding description, with this lever 
arrangement 15 a very simple and yet effective structure is accomplished 
in order to obtain high-degree reliability of the food processor to the 
effect that the food processor is prevented from operating until the 
processing container 4, 5 and its respective lid 10, 11 are properly 
positioned, thus ruling out the possibility for the user to reach inside 
an open processing container 4, 5 while the processing tool 9 is running.