Description

Background

The invention relates to the field of working tools, specifically blades, for kitchen appliances used for food processing.

Prior art

Different working tools are known for use in kitchen appliances. The working tools may have a varying number of blades of varying shapes and sizes. The aim is for the working tool with blades to process food in the shortest possible time, with low energy consumption. The working tool should chop and mix the ingredients in the vessel completely. Since the aim is for the food to be processed at the highest possible peripheral velocity, which in turn is at its highest at the furthest point away from the rotation axis, the working tools should be designed in such a way that the majority of the sharp processing surfaces of the working tool are on this part of the working tool, i.e. as far away as possible from the center of rotation. A vortex is created during the rotation of the working tool, ensuring that the food ingredients are uniformly distributed and mixed throughout the processing vessel.

The working tool is driven by a motor, the velocity of which can be regulated by changing the current using a user switch or button. When processing solid food at a low rotation velocity, there is a danger of the motor overheating due to overload. The typical kitchen appliance (e.g. mixer or food processor) does not have a gearbox to change the velocity. Instead, an electromechanical device is used - a button or an electric switch - to connect different stator windings for different velocities.

The working tools usually used in commercially-available kitchen appliances have two or four blades which differ in shape and arrangement. The working tool blades may have a conical finish, making the blade sharp and enabling it to cut through the contents of the mixer more easily. The blades can also be stamped out, ground or serrated. The manufacturing of such working tools is easy enough for mass production, e.g. stamping, grinding and serration.

The known solutions often have problems in processing food in the initial phase, when the large, unprocessed pieces of food ingredients may get stuck in certain areas of the processing vessel, causing unprocessed food to remain at the end of the processing, or reducing the rotation frequency, thereby overloading the motor. This is often a hydrodynamic problem, in which it is very important to optimize the pattern and the velocity of circulation of the food being processed around the processing vessel in the time from one contact with the blade to the next.

Purpose of the invention

The purpose of the invention is to improve the shape of working tools for kitchen appliances, enabling better food processing, especially at low rotation velocities.

Solution to the problem

In order to achieve the purpose of the invention, a working tool for a kitchen appliance according to Claim 1 i described. As a second aspect of the invention, a kitchen appliance used to process food according to Claim 9 is described. Embodiments that can be implemented individually or in any combination thereof are the subject of the dependent claims.

According to the first aspect of the invention, a working tool for a kitchen device, adapted to be rotationally driven, consisting of two or more blades for food processing is described, wherein at least one blade consists of the inside part of the blade and the outside part of the blade, and in which each inside part of the blade is in contact with the holder, while the plane of the inside part of the blade is substantially perpendicular to the rotation axis, and each outside part of the blade is in the vicinity of the wall of the processing vessel and its plane is substantially parallel to the rotation axis. This geometry enables the blade planes to be directed substantially parallel to the bottom and the walls of the processing vessel, reducing the possibility of food being stuck between the working tool and the vessel, reducing the risk of overloading the motor and blocking the working tool, especially during working tool startup.

The second aspect of the invention describes a kitchen appliance used to process food, adapted to use the working tool according to Claim 1.

The purpose of the invention is achieved by optimizing the working tool, specifically blade, geometry in such a way that the rotation of the processed food ingredients in the processing vessel is directed in such a way as to reduce as much as possible the risk of the processed food being stuck in areas where it might remain unprocessed, or the risk of motor disturbance, e.g. reduced rotation frequency or a full stop.

Embodiments of the invention

The embodiments which can be used individually or in any combination are subject of the subclaims.

The priority method of practicing the invention uses the outside part and the inside part of the working tool blades to process food. The outside parts of the blades of the working tool are rotating at the highest velocity. The shape of the working tool according to the invention has a large portion of the length of the blade in this area, which is due to the twisting of the outside parts of the working tool blades into the direction that is parallel to the rotation axis. This increases the food processing performance while reducing the risk of the food being stuck between the blade and the walls of the food processing vessel.

The second priority method uses a working tool with two blades, in which one outside part of the blade is oriented in one direction in regard to the rotation plane of the inside part of the blade, while the other outside part is oriented in the opposite direction. This achieves the highest possible distribution of cutting surfaces along the perimeter column of the food processing vessel. As stated before, the velocity and therefore the food processing performance is highest in this area.

Furthermore, the outside parts of the blades have an exit angle of 5-25°, preferably 15°, in the direction of rotation in regard to the perpendicular line to the plane of the inside parts of the blade. The performance of a rotating blade is highest if the blade is twisted forward in the direction of rotation. In addition to this effect, which is known from theory and has been confirmed in methods of practicing the invention, by tilting the outside part of the working tool blade, the tip of the blade can be offset in the direction closer to the food processing vessel wall. This is especially advantageous on the outside part of the blade which is curved upwards in case the vessel expands slightly along the radius towards the top part.

In a further embodiment, the exit angle of the tips of the outside parts of the blades is 20-50°, preferably 30°, to the perpendicular of the plane of the inside parts of the blades. Such geometry of the blade allows for a curved surface, which on the one hand increases the length of the blade, while varying the angles at which the blade makes contact with the food in the vortex, which can contribute to better and faster food processing. The shapes used may deviate from this shape, e.g. wavy shapes, serrated shapes etc.

In one of the methods of practicing the invention, the outside parts of the working tool blades are preferably sickle-shaped. This shape is a logical embodiment of the outside part of the working tool blade, as the exit angle of the outside parts of the blade against the perpendicular of the plane of the inside part of the blade is closer to zero degrees at the contact area between the inner and outer parts of the blade and the exit angle against said perpendicular at the tips of the outside parts is substantially larger.

In another embodiment, the functionality of the working tool is further improved with the inside parts of the working tool blades sharpened on the side in the direction towards the bottom of the processing vessel in order to produce a vortex directing the processed food in the direction towards the bottom of the processing vessel. This increases the exit radial velocity from the contact of food with the blade in the direction of the vortex in which the food rotates, positively influencing the food processing velocity and decreasing the risk of food being stuck.

Additionally, it is advantageous for the outside parts of the blades of the working tool to be sharpened on the outside, in the direction of the wall of the processing vessel. In addition to the radial component of food vortex acceleration, active directing of the food towards the bottom of the vessel was proven to have very positive effects, as it enables the area between the working tool and the bottom of the processing vessel to be included in the food vortex, thereby decreasing the possibility of food sticking or remaining in this area.

"Substantially parallel" and "substantially perpendicular" according to this invention are to be understood with some tolerance, that is with a possible deviation from the mathematical parallel and perpendicular relations by up to 15 degrees in either direction.

Brief description of the drawings

Figure 1 shows a 3D model of the kitchen appliance working tool.

Figure 2 shows the main trajectories of circulation of food being processed in the processing vessel.

Figure 3 shows the trajectories in the vicinity of the blades of the working tool.

Detailed description of the invention

Figure 1 shows the working tool 1 for kitchen appliances. The working tool 1 is adapted in for faster processing of the food ingredients and for achieving higher exit velocities of the external vortex 7 (Figures 2 and 3). The working tool 1 is designed in such a fashion that it has outside parts 4 at the end of both blades 2, which are bent at the maximum radial distance from the rotation axis permitted by the shape of the processing vessel 5. One of the outside parts 4 is bent upwards, substantially perpendicular to the plane of the inside parts 3 of the blades 2, while the other is bent downwards, towards the bottom of the processing vessel. Preferably the planes of the working tools are substantially parallel to the contour of Processing Vessel 5 in the direction of the axis of rotation.

The outside parts 2 of the working tool 1 , the planes of which are substantially parallel to the rotation axis, have an exit angle of 5-25°, preferably 15°, towards the wall of the processing vessel 5 in the direction of rotation of the working tool 1 . The outside parts 4 of the blades 2 of the working tool 1 are then preferably sickle-shaped, whereby the final angle at the tips of the working tool 1 is 20-50°, preferably 30°. As per the theory of rotor turbines, this shape of the blades 2 of the working tool 1 increases the transfer of energy from the blades to the food being processed. This enables better displacement of the processed food towards the internal wall of the processing vessel 5. The radial velocity of the working tool 1 is the highest possible radial velocity permitted by the limited radius of the processing vessel 5, thus increasing the circulation and mixing of the food being processed in the food processing vessel 5. This increases the radial exit velocity of the food being processed after contact with the working tool 1. The outside parts 4 of the blades 2, i.e. the outside part 4 of the blade 2 which is bent upwards in regard to the plane of inside parts 3 of the blades 2, and the outside part 4 of the blade 2 of the working tool 1 , which is bent downwards, can be of the same or different size and shape, however the balance of the working tool 1 during rotation must be maintained.

Figure 2 shows the vortex 7 of the circulation of food being processed in the processing vessel 5. The working tool 1 is sharpened on all the forward parts of the working tool in the direction of rotation. In order to improve both the velocity and the pattern of circulation, the outside parts 4 of the blades 2 of the working tool 1 are sharpened on the outside, that is on the part further away from the center of rotation, in order to direct the flow of the processed food predominantly in the direction towards the wall of the processing vessel 5 (Figure 3). The inside parts 3 of the blades 2 of the working tool 1 are sharpened on the bottom, that is on the side facing the bottom of the processing vessel 5, in order to direct the flow of the processed food predominantly towards the bottom of the processing vessel 5. With the exception of the sharpened parts of the working tool 1 , all surfaces of the blades 2 are preferably positioned substantially parallel to the bottom or the wall of the processing vessel 5, thus reducing the risk of food being stuck between the working tool 1 and the processing vessel 5. Furthermore, the surfaces where the food is being processed could become stuck due to the large distance to the cutting edge of the blade 2 of the working tool 1. This arrangement is especially important during starting of the working tool 1 , as the angular velocity and the power of the working tool 1 are at their lowest, increasing the risk of the food getting stuck.

The working tool 1 is sharpened on the inside part 3 of the blades 2, the plane of said inside part 3 being substantially perpendicular to the axis of rotation, resulting in the processed food being directed towards the bottom of the vessel and then returning to the top, increasing the circular component of the movement of the food being processed. Without such sharpening, the inside part 3 of the blade 2 of the working tool 1 would only deflect and partially break chunks of the food being processed, e.g. pieces of carrot, possibly causing them to get stuck and decreasing the rotation frequency. The effects of circular movement can be increased by introducing tilting of the inside parts 3 of the blades 2 of working tool 1 in relation to the plane perpendicular to the direction of rotation, which would result in an additional upward or downward force enabling an improved rotational stabilization of the blades 2 of the working tool 1 .

List of Reference Numerals

1 working tool

2 blade

3 inside part of the blade

4 outside part of the blade

5 processing vessel

6 holder

7 vortex of circulation of food being processed