The present invention relates to a cooking hob, and in particular a cooking hob with downdraft extraction for extracting cooking fumes, vapours and the like. The invention further relates to a housing suitable for use in such a cooking hob and a control unit suitable for use in such a cooking hob.

Cooking hobs utilizing downdraft extraction are known and widely sold in the consumer market. Many of such cooking hobs comprise a tightly integrated downdraft extractor arrangement to achieve a compact cooking hob design suitable for placement in a kitchen countertop. Typically, a support plate of the cooking hob for support and heating of cooking vessels is provided with an air inlet opening to draw in cooking fumes and vapours in downward direction. Many cooking hobs utilize internal ducting to connect the air inlet opening in the support plate to an extractor arrangement below the support plate. The internal ducting often accommodates collection means for liquids that may accidentally leak into the air inlet opening.

Because of the compact design of cooking hobs mentioned above, there is limited space for components such as a downdraft extractor, internal ducting, filter arrangements and electronics. As a result, trade-offs are often made between requirements related to extraction efficiency, component serviceability, usability and cleanability.

The present invention seeks to address the aforementioned trade-offs of prior art cooking hobs by seeking to further optimize requirements regarding extraction efficiency, acoustic noise and serviceability and cleanability whilst maintaining a compact cooking hob design.

According to the present invention, a cooking hob is provided comprising a support plate configured for supporting one or more cooking vessels, and wherein the support plate comprises an extraction opening for extracting air, wherein the cooking hob further comprises a housing arranged below the support plate, wherein the housing comprises an air inlet end and an air outlet end, wherein the air inlet end is connected to the extraction opening, and wherein the air outlet end is configured for connection to a fan arrangement, wherein the cooking hob comprises a control unit, the control unit comprising control elements, and wherein the control unit is mounted to the housing.

By connecting the control unit to the housing, preferably an underside of the housing, the control unit is easily accessible for maintenance and servicing.

The housing may also be referred to as an extraction housing. The housing provides for an air connection between the extraction opening and the fan arrangement, which is to be connected to the air outlet end of the housing. The arrangement helps to remove cooking odours, smoke, steam, and grease from the air while cooking. The housing comprises an air flow channel stretching from the air inlet end to the air outlet end.

The housing may comprise a bottom wall in which the air outlet end is arranged.

The cooking hob is configured to be positioned on a surface with the support plate being substantially horizontal. The cooking hob has a height direction, being perpendicular to the support plate. The cooking hob has a depth direction running from the front side of the cooking hob to the backside of the cooking hob. The backside is configured to face a wall or other object, like another kitchen part. The front side is opposite the backside and is configured to be directed to an open space of the kitchen to allow a user to approach the cooking hob. The cooking hob has a lateral direction, being perpendicular to the height direction and the depth direction. The lateral direction may also be referred to as the right and left direction.

The control unit may be any kind of control unit configured to control parts of the cooking hob, such as the fan arrangement. The control unit may also be referred to as a motor control unit. The main purpose of the control unit is to control the motor of the fan arrangement. The control unit may control the motor of the fan arrangement based on user input and/or based on input from sensors.

The controller may be an electronic or computational device designed to manage, regulate, and coordinate the operation of various components or subsystems of the cooking hob. The controller may receive input signals from sensors or user interfaces, process these signals according to predefined algorithms or software, and generate output signals to actuate or control the various components or subsystems of the cooking hob. In particular, the control unit is configured to control the fan arrangement by sending control signals to the fan arrangement.

The controller may comprise several input/output terminals to communicate with sensors, actuators, user interfaces and other peripheral devices. Inputs may include data from sensors or signals received from user via an appropriate user interface. Outputs may be control signals for the fan arrangement.

The controller may be configured to operate based on (embedded) software or firmware that defines the control logic. This software can be programmed to perform specific tasks.

According to an embodiment the control unit is positioned against a bottom wall of the housing.

The control unit may be mounted to the bottom wall of the housing. This has the advantage that the control unit can be approached by service personnel or users without needing to remove the housing or support plate.

According to a preferred embodiment the control unit (100) is positioned against a horizontal part of a bottom wall (19) of the housing (4).

According to an embodiment the control elements being one or more of the following: a circuit board, a processing unit, an input/output terminal, window switch, and power connectors.

The control elements provide the control unit with the desired functionality.

The control elements may comprise a circuit board or printed circuit board. A circuit board provides a platform to mechanically support and electrically connect electronic components using conductive pathways, traces, and other features. It ensures that the components are correctly positioned and connected to perform their intended functions within an electronic device.

The control elements may comprise a processing unit, which can be a microcontroller, microprocessor, or programmable logic controller (PLC). The processing unit is responsible for executing instructions and algorithms to control other components to provide the control unit and the cooking hob with the desired functionality. The processing unit may be mounted on the circuit board, typically on a socket or directly soldered onto the circuit board.

The control element may further comprise one or more input/output terminals configured to be connected to appropriate cables. The cables may include power cables, to provide the control unit with the required power and signal cables to transmit input signals to the control unit and output signals from the control unit.

The control elements may also comprise power connectors configured for connecting the control unit to an appropriate electrical power source, such as the mains.

The control elements may also comprise a window switch. A window switch is an element that is able to receive a window signal indicating the open or closed state of a nearby kitchen window. The window switch may be connected to a window sensor via a cable connection or a wireless connection. The window switch can switch the fan arrangement on or off depending on the state of the nearby kitchen window as indicated by the window signal. If the window is open, the fan arrangement may be switched on. If the window is closed, the fan arrangement may be switched off or may be blocked from being switched on. Of course, further parameters may be taken into consideration as well, such as for instance if the cooking hob is in use or not.

According to an embodiment the control unit comprises a lid that is moveable between a closed position and an open position, wherein at least one of the control elements is positioned on an inside of the lid.

By providing a lid that is moveable between a closed and open position and comprises at least one control element, the control unit can be easily installed, serviced or maintained. In the closed position, the inside of the lid faces towards the housing, i.e. the bottom wall of the housing, thereby providing protection for the control elements. By moving the lid to the open position the control elements provided on the inside of the lid become easily accessible.

According to an embodiment the power connectors are positioned on the inside of the lid, and wherein the lid comprises a door which provides access to the power connectors when the lid is in the closed position.

The power connectors need to be connected to an electrical power source. By providing a door in the lid which can be opened when the lid is in the closed position, access can be provided to the power connectors without fully opening the control unit by moving the lid to the open position. This facilitates connecting the control unit to an appropriate electrical power source, such as the mains.

According to an embodiment the lid is mounted to the housing in the closed position and in the open position.

The lid is configured to remain connected to the housing, i.e. the bottom wall 19, even when in the open position. This facilitates servicing the control unit as there is no need to remove the lid from the cooking hob or temporarily store the lid at a safe location during servicing.

According to an embodiment the lid is rotatable mounted to the housing, wherein the lid is rotatable about an axis of rotation which is directed in a substantially lateral direction of the cooking hob.

The lid is configured to rotate between the open position and the closed position. The lid is preferably connected to the housing by means of one or more hinges.

The axis of rotation R is oriented substantially laterally. The term substantially lateral is used to indicate that the axis of rotation is at an angle to the lateral direction of less than 45 degrees, preferably less than 30 degrees, more preferably less than 10 degrees and most preferably less than 5 degrees. The axis of rotation R is preferably horizontal.

According to an embodiment the inside of the lid faces towards the front of the cooking hob when the lid in the open position.

Preferably, the lid is rotatable about a lateral axis of rotation such that the inside of the lid faces towards the front of the cooking hob. This provides easy access to the control elements positioned on the inside of the lid.

According to an embodiment the lid forms a box with the housing when the lid is in the closed position.

This provides a protective environment for the control elements. In particular, the lid forms a box with the bottom wall of the housing when in the closed position. The box may be substantially closed to protect the interior of the box, but this doesn't exclude the presence of openings, for instance for cables running between the interior and the exterior of the box. The box is thus formed by the lid and part of the bottom wall of the housing.

According to an embodiment the lid comprises a main part with a side wall.

The main part may also be referred to as the base plate of the lid. The main part may be rectangular. The side wall may be formed by protruding side wall elements. The side wall may be integrally formed with the main part and extend upward along the edges of the main part in the direction of the housing to which the lid is attached (when in the closed position). The housing of the cooking hob, in particular the bottom wall, and the side wall may be shaped correspondingly to result in a stable connection when the lid is in the closed position. The side wall may be designed to fit snugly with the housing, ensuring a secure closure. According to this embodiment the lid is formed as an open container, configured to contain the control elements. Such a lid provides for a protective space for the control elements.

According to an embodiment the housing and the side wall are configured to engage.

The housing and the side wall may be formed correspondingly to engage when the lid is in the closed position, preferably to lock the lid in the closed position. Preferably, the housing and the side wall are formed to form a snap fit connection, allowing the lid to be closed by pressing the lid against the housing, thereby locking the lid in the closed position. The lid can be moved to the open position by exerting a sufficient manual force.

The housing and the side wall may form matching snap-fit features. The housing and the side wall are preferably made from plastic that can deform slightly to facilitate the snap-fit connection.

According to an embodiment the lid and the housing are configured to lock the lid in the closed position.

The lid and the housing may comprise one or more corresponding, aligned screw holes configured to receive a screw and thereby lock the lid in the closed position. This provides for a secure closure of the lid meeting safety requirements and preventing the lid from being opened unintentionally.

According to an embodiment the side wall comprises a cable passage, wherein the cable passage is located close to the axis of rotation.

Cables need to be connected to at least some of the control elements, e.g. to provide the control elements with power, input signals and to allow control signals to be send by the control elements. The cables are to be connected to appropriate input/output terminals. When the lid is moved between the closed position and the open position by rotating the lid about the axis of rotation, the cables running in and out of the control unit need to move along. It is therefore advantageous to provide the cable passage close to the axis of rotation, to minimize the movement of the cables and to minimize the extra length of the cables that needs to be provided to allow this movement between the open position and the closed position.

The term close is used to indicate that the cable passage is equal or less than a distance D away from the axis of rotation, wherein distance D is 6 cm, preferably 5 cm, more preferably 4 cm and most preferably 3 cm seen in a projected height direction (thus seen in a top or bottom view). The distance D is measured from the axis of rotation R to a part of the cable passage closest to the axis of rotation when seen in a height direction when the lid is in the closed position. The term close may alternatively be expressed in relative measures, where the distance D is less than 50%, preferably less than 40%, more preferably less than 30% and most preferably less than 20% of the total depth of the lid.

The cable passage is preferably formed by providing a lowered portion in a top edge of the side wall, thereby creating a recess in the side wall forming the cable passage. The cable passage is open when the lid is in the open position, allowing cables to be put in the cable passage. When the lid is in the closed position, the cable passage is closed by the housing, thereby securing the cables. The cable passage may be formed as a recess in the side wall, preferably the part of the side wall facing the fan arrangement. The cable passage may be formed as a rectangular recess in the side wall.

The cable passage is preferably formed in a part of the side wall that runs perpendicular to the axis of rotation.

According to an embodiment the side wall comprises a cable strain relief opening.

The cable strain relief opening is preferably positioned close to the cable passage. The term close to is used to indicate that a minimal distance between the cable strain relief opening and the cable passage is less than 2cm, preferably less than 1 cm.

This cable strain relief opening allows to secure the cables in the cable passage by using a tie wrap or other similar means. The tie wrap can be provided through the cable strain relief opening and around one or more cables, thereby securing the cables in the cable passage and making sure the cables move with the lid when the lid is moved between the open and closed position.

According to an embodiment the lid comprises two aligned first hinge elements, and wherein the housing comprises two aligned second hinge elements, wherein the first and second hinge elements are configured to engage each other to form a hinged connection.

The first hinge elements may be two aligned openings running in lateral direction, and the second hinge elements may be two aligned cylindrical axes, configured to be secured in the openings to form a hinged connection. Alternatively, the second hinge elements may be two aligned openings running in lateral direction, and the first hinge elements may be two aligned cylindrical axes, configured to be secured in the openings to form a hinged connection. The first and second hinge elements may be secured to each other by means of a snap-fit connection.

According to an embodiment, the lid may comprise two opposing raised hinge flanges, which may be formed integrally with the lid and may in particular be formed integrally with the side wall of the lid. The raised hinge flanges are raised with respect to the side wall (other than the raised hinge flanges). Each raised hinge flange may be provided with a first hinge element.

According to an alternative embodiment, the housing may comprise two opposing lowered hinge flanges, protruding downwardly from the bottom of the housing. The lowered hinge flanges may be formed integrally with the housing. The lowered hinge flanges may be lowered with respect to the bottom. Each lowered hinge flange may be provided with a second hinge element.

According to an embodiment the side wall comprises a raised rear side wall part.

The raised rear side wall part may be positioned behind the axis of rotation, i.e. closer to the backside of the cooking hob than the axis of rotation. The raised rear side wall part may run parallel to the axis of rotation. The raised rear side wall part may have a top edge that is above the axis of rotation when the lid is in the closed position, seen in a direction parallel to the support plate. Preferably, the top edge of the raised rear side wall part may be at least 8 mm above the axis of rotation when the lid is in the closed position. This has the advantage that when the lid is rotated from the closed to the open position, the raised rear side wall part rotates over the axis of rotation, thereby preventing objects or fingers from become stuck between the lid and the housing and also preventing objects or fingers from accessing the area behind the lid.

According to an embodiment the housing comprises a lowered wall part, wherein the lowered wall part runs parallel to the axis of rotation and wherein the lowered wall part is positioned in the vicinity of the axis of rotation.

The lowered wall part may be positioned behind or in front of the axis of rotation, i.e. closer to or further away from the backside of the cooking hob than the axis of rotation. This has the advantage that when the lid is rotated from the closed to the open position, the lowered wall part prevents objects or fingers from becoming stuck between the lid and the housing and also preventing objects or fingers from accessing the area behind the lid.

According to an embodiment the housing encloses an air flow channel that extends between the air inlet end and the air outlet end, wherein the air outlet end is laterally offset from the air inlet end in a first direction, and wherein the control unit is laterally offset from the air inlet end in a second direction, the second direction being opposite the first direction.

The lateral offset of the air outlet end from the air inlet end provides space in lateral direction for positioning the control unit in a space efficient manner. This provides for a compact design, in particular in the height direction of the cooking hob. By offsetting the air outlet end in a first lateral direction, space is created to position the control unit laterally offset with respect to the air outlet end. In other words, the air flow channel and the control unit can be positioned on lateral opposite sides of the cooking hub, thereby saving space in the height direction.

According to an embodiment, the cooking hob has a width of 560mm and/or the cooking hob is suitable to be placed in a standard 600 mm kitchen cabinet.

According to an embodiment, the cooking hob has a height of 234 mm or less, including the support plate.

According to an embodiment the cooking hob comprises a fan arrangement arranged below the housing and connected to the air outlet end for extracting air through the extraction opening, wherein the fan arrangement comprises an extraction outlet laterally centred with respect to the support plate or extraction opening.

The fan arrangement is preferably positioned horizontally, i.e. having an axis of rotation that is substantially vertical,

The lateral offset of the air outlet end from the air inlet end provides space in lateral direction for the extraction outlet being laterally centred with respect to the support plate or the extraction opening. Having such a centred extraction outlet greatly facilitates installation as an installer is not faced with cumbersome measurements as to where ducting must be positioned for connection to the extraction outlet. This allows for easy and symmetrical instalment of the cooking hub. Any exhaust duct to be connected to the extraction outlet can be positioned in the middle of the cooking hub seen in lateral direction.

According to an embodiment the control unit is positioned laterally adjacent to the fan arrangement.

By positioning the control unit laterally adjacent to the fan arrangement, the overall height of the cooking hob can be kept low.

According to a further aspect there is provided a housing suitable for use in a cooking hob according to any one of the embodiments above, wherein the housing is configured to be arranged underneath a support plate, the support plate being configured for supporting one or more cooking vessels and the support plate comprising an extraction opening for extracting air, wherein the housing comprises an air inlet end and an air outlet end, wherein the air inlet end is configured for connection to the extraction opening, and wherein the air outlet end is configured for connection to a fan arrangement, wherein the housing is configured for mounting a control unit to the housing, preferably wherein the housing is configured to mount a control unit to the housing.

The housing may enclose an air flow channel that extends between the air inlet end and the air outlet end, wherein the air outlet end is laterally offset from the air inlet end in a first direction, and wherein the control unit is laterally offset from the air inlet end in a second direction, the second direction being opposite the first direction.

According to a further aspect there is provided a control unit suitable for use in a cooking hob according to any one of the preceding claims, wherein the control unit is configured to be mounted to the housing, preferably wherein the control unit is configured to be hinged to the housing.

The present invention will be discussed in more detail below, with reference to the attached drawings, in which

• Figure 1a shows a horizontal view of a cooking hob according to an embodiment,
• Figure 1b shows a horizontal front view of a cooking hob according to an embodiment,
• Figure 1c shows a front view of a cooking hob from at angle from above according to an embodiment,
• Figure 2a shows a perspective view at an angle from below of a housing of a cooking hob with a closed control unit according to an embodiment,
• Figure 2b shows a perspective view at an angle from below of a cooking hob with an opened control unit according to an embodiment,
• Figure 3 shows a bottom view of a cooking hob according to an embodiment, and
• Figure 4 shows a rear view of a cooking hob according to an embodiment.

Figure 1a - c show different views of a cooking hob 1.

The cooking hob 1 comprises a support plate 2 on top. The support plate 2 is suitable for supporting cooking vessels (not shown). The support may be made of glass. The support plate 2 comprises an extraction opening 3 (best shown in Fig. 1c) for extracting air. The extraction opening 3 is positioned centrally in the support plate 2. The cooking hob 1 may comprise induction loops, which may be made of tightly wound copper wires and are located close to the upper surface of the support plate 2. When the cooking hob 1 is turned on, an alternating current flows through the induction loops, creating a rapidly changing magnetic field, which can be used to heat cooking vessels. The induction loops are not shown in the Figures and will not be further described.

The cooking hob 1 further comprises a housing 4 and a fan arrangement 7.

The housing 4 is provided underneath the support plate 2. The housing 4 is more clearly shown in Fig. 2a, showing a perspective view of the housing 4 (without support plate or fan arrangement) at an angle from below. The housing 4 comprises an air inlet end 5 (indicated in Fig. 1b), provided on a top side of the housing 4. The air inlet end 5 is configured to be connected to the extraction opening 3. The air inlet end 5 is therefore positioned centrally in a lateral direction. The housing 4 comprises an air outlet end 6 downstream of the air inlet end 5. The air outlet end 6 can be connected to a fan arrangement 7. The housing 4 comprises an air flow channel fluidly connecting the air inlet end 5 to the air outlet end 6.

As shown in Fig. 1b, the air outlet end 6 is offset with respect to the air inlet end 5 in lateral direction over a distance Ox. Where the air inlet end 5 is positioned centrally in lateral direction, the air outlet end 6 is offset in a lateral direction from this central position. This provides space for advantageous positioning of the control unit 100 in the opposite lateral direction as will be discussed in more detail below.

The fan arrangement 7 comprises an extraction outlet 7a, which is positioned at the backside of the cooking hob 1 and which is centrally positioned in the lateral direction. This is more clearly shown in Fig. 4, showing a rear view of the cooking hob 1. Fig. 4 shows the extraction outlet 7a, in this case embodied as a square opening with rounded corners. The fan arrangement comprises a motor to drive a rotor to generate an air flow from the extraction opening 3 to the extraction outlet 7a. The fan arrangement 7 is positioned below the housing 4, fluidly connected to the air outlet end 6 such that the fan arrangement 7 can suck air through the extraction opening 3, the air inlet end 5, the air flow channel, the air outlet end 6 and the fan arrangement 7 towards the extraction outlet 7a.

The cooking hob 1 comprises a control unit 100, which is located at a bottom wall 19 of the housing. This is also visible in Fig.'s 2a and 2b. Fig. 2b shows a view of the housing 4 and support plate 2 at an angle from below. As a result of the offset positioning of the air outlet end 6 and consequently the fan arrangement 7 (not present in Fig.'s 2a and 2b), the control unit 100 can be positioned laterally adjacent to the fan arrangement 7, thereby saving height of the cooking hob 1.

The control unit 100 may comprise all sorts of control elements, such as a circuit board 110, a processing unit 111 and one or more input/output terminals 112 (only one being indicated by way of example in Fig. 1a). Further provided is a power connector 113 configured to connect the control unit to power, e.g. the mains. Further provided may be a window switch or window switch connection 117.

The control unit 100 comprises or may be shaped as a lid 101 that can be opened and closed, with at least some of, preferably all, the control elements being provided on an inside surface of the lid 101. The control unit 100 is shown in a closed position in Fig. 2b. The control unit 100 is shown in an open position in Fig.'s 1a-c, 2a, 3, and 4.

The lid 101 comprises a main part 102 or base plate, being a rectangular, substantially flat part. The lid 101 further comprises a side wall 103 that runs along the edge of the main part 102. The side wall 103 is best shown in Fig. 1a. The side wall 103 is provided at a 90 degree angle with respect to the main part 102. The main part 102 and the side wall 103 together form an open box in which one or more of the control elements may be provided. By moving the lid 101 to the closed position, the open box is closed by the bottom of the housing.

The lid 101 is connected to the housing 4 with a hinge construction. As best visible in Fig. 2a, the control unit comprises two opposing raise hinge flanges 104. The raised hinge flanges 104 are provided towards the rear end of the control unit 100, i.e. the side directed to the rear side of the cooking hob 1. The raised hinge flanges 104 are provided with a hinge element. The housing 4 may comprise complementary hinge elements that can engage with the hinge elements provided on the raised hinge flanges 104 to form a hinged connection. This allows the control unit 100 to be rotated about an axis of rotation R between a closed position and an open position. The axis of rotation, as shown in Fig.'s 1b, 2a and 2b, runs in a lateral direction. The control unit 100 is hinged to the housing such that the inside of the lid 101 is facing towards the front side of the cooking hob 1 when the control unit 100 is in the open position, thereby exposing the control elements.

As shown in Fig. 1a, the side wall 103 has a cable passage 105. The cable passage is formed by providing a lowered portion in a top edge 107 of the side wall 103, thereby creating an open space through which cables can run. The cables can be inserted in the cable passage when the lid 101 is in the open position..

The cable passage 105 is positioned at a part of the side wall 103 that is at the side of the air outlet end 6 and the fan arrangement 7. As best shown in Fig. 3, the fan arrangement 7 comprises a cable channel 71 running from the cable passage 105 to the centre of the fan arrangement 7 where the motor of the fan arrangement is positioned, to provide the fan arrangement 7 with power and control signals.

Although Fig. 3 shows a bottom view of the cooking hob 1 with the control unit 100 in open position, it can be used to show the relative position of the cable passage 105 with respect to the axis of rotation R. This distance D is indicated in Fig. 3. The right dotted line indicates the axis of rotation R. The left dotted line shows the location of the part of the cable passage 105 closest to the axis of rotation R when the lid is in the closed position. The lid 101 is opened in Fig. 3, but it will be understood that the cable passage 105 will align with the cable channel 71.

The lid 101 comprises a screw hole 115 at a front side to securely fix the lid 101 in the closed position by screwing the lid to the housing 4. The housing 4 comprises a corresponding screw hole 8 (see Fig. 3). The screw hole 115 provided in the lid 101 may be formed integrally with the lid 101.

The lid 101 further comprises a door 114 allowing access to power connectors 113 when the lid is in the closed position. Fig. 2b and 4 show the door 114 in a fully opened position, revealing power connectors 113.

The lid 101 may further comprise cable securing features 116, as best shown in Fig. 1c and 2a. These cable securing features 116 are configured to hold cables in place and help to organize the cables. The cable securing features 116 may be formed by protrusions that extend from the inside of the lid, in particular from the main part 102 and/or the side walls 103. The cable securing features may be configured with an opening into which a cable can be pressed. Once inserted, the cable is secured by the compressive force exerted by the walls of the opening, effectively squeezing the cable and preventing it from dislodging.

Alternatively, the cable securing features 116 may be protrusions positioned to define a predetermined curved path. A cable can be put in place along the path, where it is hold in position by the cable securing features 116 by leveraging the inherent rigidity of the cables. Hereby it is ensured that the cables remain securely in place. The cable securing features 116 also prevent the cables from being disconnected when external force is exerted on the cables, for instance by users or service personnel or caused by opening or closing the lid. The cable securing features 116 also function as cable strain reliefs.

Fig. 2a shows the side wall 103 being raised at the rear part forming a raised rear side wall part 103'. The raised rear side wall part 103' is positioned behind the axis of rotation R. The raised rear side wall part 103' is dimensioned such that it blocks most of the gap between the rear side wall 103 and the bottom wall 19 to prevent objects or users from accessing the area behind the control unit 100 or getting stuck between the housing 4 and the lid 101.

The present invention has been described above with reference to a number of exemplary embodiments discussed above and as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.