Two-sided cooking appliance

Abstract

A cooking appliance 10 comprises an upper platen assembly 15 comprising an upper platen 16, a lower plate 14 for receiving food mounted to a main body 12, and a movement mechanism 18 for adjusting the

Description

Technical Field The present disclosure is directed towards a two-sided cooking appliance, also known as a clamshell grill, for cooking food between an upper platen and a lower plate. Background Numerous forms of cooking appliances are available. In a traditional griddle or a flat top grill, food can be placed onto a heated cooking surface and must be flipped by the user if they wish to cook the food on both sides. This requires the user to dedicate their attention to the food to be cooked and carefully time the flipping of the food items, particularly when the food items are being cooked in large batches such as in commercial kitchens. Clamshell grills (also referred to as two-sided grills) are commonly used, especially in commercial kitchens, to cook items such as burger patties by providing heating from both above and below the food items to be cooked. Typical clamshell grills comprise an upper platen and a lower cooking plate, with the upper platen moveable between a cooking and non-cooking position. Ideally, the non-cooking position will have the upper platen tilted upwards and away from the lower plate, such that the user can easily and safely access the entire area of the lower plate, in particular the area furthest from the user, at the back of the lower plate. The upper platen can typically be moved manually, through the use of a handle, or automatically. Clamshell grills allow for shorter cooking times than traditional flat top grills as the food in between the two plates is heated from two sides. Additionally, clamshell grills in commercial kitchens allow for consistent cooking, especially when cooking large batches of food, and simplicity in training kitchen staff, as the food items do not have to be flipped one at a time to be cooked on both sides and all the way through. Automated clamshell grills are programmable with pre-selected temperature, cooking time, and platen gap depending on the food items to be cooked and their properties, such as the thickness of a burger patty. Automated clamshell grills allow users to complete other tasks while the food is cooking, increasing efficiency in commercial kitchens. US11317760B2 discloses a grill having a movable upper platen and a lower platen, the latter of which holds food products that are cooked between the platens. The upper platen has a platen arm, locking drive, and locking pin connected thereto. An actuator, drive shaft, and drive shaft head are operably connected to the platen arm. During operation of the grill, the locking drive drives the locking pin into the drive shaft head, holding the upper platen parallel to the lower platen. However, such a clamshell grill requires a complex mechanism comprising multiple actuators and hydraulic systems for the raising, lowering, and tilting of the upper platen with respect to the lower plate. This mechanism is also expensive to manufacture. Summary An object of the present invention is to provide an improved clamshell grill, with an improved mechanism for the raising, lowering, and tilting of the upper platen. The present invention therefore provides a cooking appliance comprising: an upper platen assembly comprising an upper platen; a lower plate for receiving food items and mounted to a main body; and a movement mechanism for adjusting the height and angle of the upper platen assembly relative to the lower plate, wherein the movement mechanism comprises: an arm arrangement comprising at least one arm extending from the mechanism housing to a pivotal connection with the upper platen assembly, wherein the at least one arm is adjustable so as to raise and lower the upper platen assembly relative to the lower plate between an upper position and a cooking position; and a stop arrangement for abutting the upper platen and limiting pivoting of the upper platen assembly relative to the arm arrangement around the pivotal connection such that in the upper position the upper platen is non-parallel to the lower plate and in the cooking position the upper platen is parallel to the lower plate. Generally, in the present invention, the movement mechanism has been significantly improved and simplified compared to those of the prior art as the raising, lowering, and tilting of the upper platen can be controlled by a single linear actuator. Additionally, the raising or lowering of the upper platen occurs in a single smooth motion alongside the tilting without having a separate mechanism for the tilting of the upper platen relative to the lower platen. The movement mechanism of the present invention is simpler and cheaper to manufacture than those of the prior art. The cooking position of the upper platen may be parallel to the lower plate by an angle therebetween being less than 10°. The raising and lowering of the upper platen assembly may comprise moving the upper platen assembly perpendicular to the lower plate. The arm arrangement may comprise a first arm extending between first and second ends, the first end being mounted to or in the main body, wherein the first arm is moveable perpendicular to the lower plate; and a second arm, wherein the second arm extends from the second end of the first arm to a pivotal connection with the upper platen assembly, the first and second arms being non-parallel and / or non-perpendicular to one another. The cooking appliance may comprise a linear actuator for moving the arm arrangement. The cooking appliance may comprise at least two arm arrangements. The at least two arm arrangements may provide a stable connection between the movement mechanism and the upper platen. The arm arrangement may be pivotally connected to the upper platen assembly by the pivotal connection such that the upper platen assembly is biased to pivot about the pivotal connection into the stop arrangement. The pivotal connection may be positioned offset from the centre of the upper platen and / or separated at a pivot height from the upper platen. The centre of mass of the upper platen assembly may be between the pivotal connection and a front of the upper platen assembly. The pivotal connection may be to an upper housing of the upper platen assembly. The position of the pivotal connection may provide the torque which leads to the tilting of the upper platen from the upper position to the cooking position. The connection to the upper housing may ensure that the width of the upper platen is not limited by the width of the mechanism housing or the distance between arm arrangements when there are two arm arrangements. The stop arrangement may comprise a first stop for abutting the upper platen assembly when the upper platen is between the intermediate position and the upper position; and a second stop for abutting the upper platen assembly when the upper platen assembly is between an intermediate position and the cooking position. The first stop may be configured to maintain the upper platen non-parallel to the lower plate when the upper platen assembly is moved between the intermediate position and the upper position and / or allow the angle of the upper platen relative to the lower plate to increase when the upper platen assembly is moved from the intermediate position to the upper position. The second stop may be configured to maintain the upper platen parallel to the lower plate when the upper platen assembly is moved between the intermediate position and the cooking position. The first stop may comprise a guide member extending from and / or fixed relative to the main body for abutting the upper platen. The second stop may comprise a branch extending from the arm arrangement for abutting the upper platen assembly and limiting pivoting of the upper platen assembly about the pivotal connection. The two components of the stop arrangement, the guide member extending from the mechanism housing, and the branch extending from the arm arrangement may allow for the pivoting of the upper platen to be limited without additional moving components such as actuators in the movement mechanism. The first and second stops may be configured to abut the upper platen assembly between the pivotal connection and a rear of the upper platen assembly and / or on an opposing side of the pivotal connection to the centre of mass of the upper platen assembly. The cooking appliance may comprise electric heating elements for heating the upper platen and lower plate. Electric heating of the cooking surfaces may allow for better regulation of the cooking temperature, leading to a more consistent quality of cooked food. The cooking appliance may comprise a control arm arrangement wherein the control arm arrangement comprises a control unit for a user to input instructions and / or select a recipe, the instructions and / or recipe being configured to cause the arm arrangement to move. The cooking appliance may comprise a controller configured to receive instructions on cooking temperature, cooking time, and upper platen height and operate the cooking appliance in accordance with the instructions. The controller may allow cooking to be done efficiently in commercial kitchens by automatically operating the cooking appliance. The controller may comprise a memory for storing recipes with preset cooking temperatures, cooking times, and upper platen heights. Storing recipes in the memory of the controller may simplify the use of the cooking appliance. The cooking appliance may comprise a plurality of adjacent upper platen assemblies and lower plates. Adjacent sets of cooking surfaces may allow for efficient cooking in large batches and at different temperatures. The present invention further provides a method of operating a cooking appliance, the cooking appliance comprising: an upper platen assembly comprising an upper platen; a lower plate for receiving food items and mounted to a main body; and a movement mechanism for adjusting the height and angle of the upper platen assembly relative to the lower plate, wherein the movement mechanism comprises: an arm arrangement comprising at least one arm extending from the main body to a pivotal connection with the upper platen assembly; and a stop arrangement for abutting the upper platen assembly, wherein the method comprises adjusting the at least one arm so as to raise and / or lower the upper platen assembly relative to the lower plate between an upper position and a cooking position, wherein during the adjustment the stop arrangement limits pivoting of the upper platen assembly relative to the arm arrangement around the pivotal connection such that in the upper position the upper platen is non-parallel to the lower plate and in the cooking position the upper platen is parallel to the lower plate. The stop arrangement may comprise a first and second stop and the method may comprise limiting pivoting of the upper platen assembly by the first stop abutting the upper platen assembly between the intermediate position and the upper position; and limiting pivoting of the upper platen assembly by the second stop abutting the upper platen assembly between an intermediate position and the cooking position. The method may comprise maintaining, by the first stop, the upper platen non-parallel to the lower plate when moving the upper platen assembly between the intermediate position and the upper position and / or increasing, by the first stop, the angle of the upper platen relative to the lower plate when moving the upper platen assembly from the intermediate position to the upper position; and / or maintaining, by the second stop, the upper platen parallel to the lower plate when moving the upper platen assembly between the intermediate position and the cooking position. The cooking appliance may comprise a controller for adjusting the arm arrangement, and the method may comprise receiving instructions and / or a selected recipe from the controller; heating the upper platen and lower plate according to the instructions and / or recipe; lowering and tilting the upper platen assembly into the cooking position from the upper position; setting a gap height between the upper platen and lower plate in the cooking position in accordance with the instructions and / or recipe; timing the cooking of the food items according to the instructions and / or recipe; and raising and tilting the upper platen assembly from the cooking position into the upper position. The present invention further provides a method of calibrating the cooking appliance so as to enable it to achieve a desired gap height between the upper platen and lower plate. The gap height may be set by a user in accordance with the type and size of food to be cooked. By calibrating the movement of the arm arrangement, the cooking appliance can consistently achieve the desired gap height. Therefore, the present disclosure further provides a method of operating a cooking appliance comprising, by a controller: performing a calibration process comprising: operating an actuator to move an arm arrangement between first and second calibration positions, the arm arrangement being for moving an upper platen assembly relative to a lower plate for receiving food items therebetween; receiving sensor data from at least one sensor indicative of: the arm arrangement reaching first and second calibration positions; and the displacement of the actuator when the arm arrangement is moved between the first and second calibration positions; and determining, based upon the sensor data, an actuator displacement ratio indicative of the displacement of the actuator per unit of movement of the arm arrangement; determining a desired gap height between the lower plate and an upper platen of the upper platen assembly; operating, based upon the actuator displacement ratio, the actuator to move the arm arrangement such that the lower plate and upper platen are separated by the desired gap height. The present disclosure further provides a cooking appliance comprising a controller configured to perform such steps. The at least one sensor preferably comprises first and second limit switches configured to generate sensor data indicative of the arm arrangement reaching the first and second calibration positions respectively. The at least one sensor preferably comprises an encoder for generating sensor data indicative of the displacement of the actuator when the arm arrangement is moved between the first and second calibration positions. The first and second limit switches prevent the arm arrangement and actuator from exceeding a maximum height or falling below a minimum height. Brief Description of the Drawings By way of example only, embodiments of a cooking appliance and a method of operating such a cooking appliance in accordance with the present disclosure are now described with reference to, and as shown in, the accompanying drawings, in which: FIGURE 1 is a perspective view of the cooking appliance in the upper position; FIGURE 2 is a side elevation view of the cooking appliance in the upper position; FIGURE 3 is a side elevation view of the cooking appliance in the intermediate position; FIGURE 4 is a perspective view of the cooking appliance in the intermediate position; FIGURE 5 is a perspective view of the cooking appliance in the cooking position; and FIGURE 6 is a rear elevation view of the cooking appliance in the cooking position. Detailed Description The present disclosure relates to a two-sided cooking appliance, also known as a clamshell grill, for cooking food between an upper platen and a lower plate. The upper platen is moveable between an upper position and a cooking position. The movement mechanism for the upper platen enables there to be a single linear actuation for the raising, lowering, and tilting movements of the upper platen. As illustrated in Figures 1 to 5, the cooking appliance 10 comprises a lower plate 14, an upper platen assembly 15 comprising an upper platen 16, and a movement mechanism 18 for adjusting the height and angle of the upper platen 16 relative to the lower plate 14 between an upper position (Figures 1 and 2) and a cooking position (Figure 5). The cooking appliance 10 is for cooking food items placed on the lower plate 14 between the lower plate 14 and the upper platen 16 when in the cooking position. Both the lower plate 14 and upper platen 16 are configurable to heat and cook the food placed therebetween. The cooking appliance 10 may comprise an appliance front 101, an appliance rear 102, and a first and second appliance side 103, 104 extending between the appliance front 101 and rear 102. The largest gap between the upper platen 16 and the lower plate 14 when the upper platen 16 is in the upper position is provided towards the appliance front 101, whilst the smallest gap between the upper platen 16 and the lower plate 14 when the upper platen 16 is in the upper position is provided towards the appliance rear 102. The terms “front” and “rear” in the present disclosure refer to proximity to the appliance front 101 and rear 102 as defined above. As in the illustrated embodiment, the appliance 10 may comprise a main body 12 to which the lower plate 14 is mounted. The main body 12 may be generally cuboidal, may comprise sheet metal and may house electrical and heating components (not shown). The lower plate 14 is a surface for receiving food items and is planar (i.e. generally extends across a plane). The lower plate 14 may be a smooth, flat, continuous surface as illustrated, or may comprise grooves between ridges extending thereacross, the plane of the lower plate 14 being defined by the midpoints between the ridges and grooves. The lower plate 14 may be rectangular. The upper platen 16 is a platen for cooking food items placed on the lower plate 14 from above. The upper platen 16 is planar, may be a smooth, flat, continuous surface or comprise grooves in a similar manner to the lower plate 14, and may be rectangular. The upper platen assembly 15 comprises a platen body 17 inside which the upper platen 16 is mounted. The platen body 17 is a generally plate shaped or thin rectangular cuboidal body, i.e. having a substantially smaller height than the width and depth of the upper platen 16. The upper platen assembly 15 may comprise an upper housing 50, which may house electrical and heating components (not shown). The upper housing 50 is mounted to the platen body on an opposing side thereof to the upper platen 16. The upper housing 50 may be mounted generally centrally on an upper surface of the platen body 17 as illustrated. The upper platen 16 and lower plate 14 can be heated for cooking food items placed therebetween. The appliance 10 may comprise electrically power heating elements (not shown) for heating the upper platen 16 and lower plate 14 and located adjacent thereto. Electrically power heating elements may be mounted in the platen body 17 adjacent to the upper platen 16 and receive power from the electrical components in the upper housing 50. Heating elements may be mounted below the lower plate 14 in the main body 12. The lower plate may be heated by gas heating components in the main body 12. The upper platen 16 and lower plate 14 may be formed of metal, e.g. steel. The movement mechanism 18 may be at least partially mounted in a mechanism housing 19 of the main body 12 and comprises at least one arm arrangement 20 and a stop arrangement 30. The mechanism housing 19 may be at the appliance rear 102. The arm arrangement 20 and / or stop arrangement 30 may be generally located towards the appliance rear 102. The movement mechanism may comprise an actuator 36, preferably a linear actuator 36, in communication with the arm arrangement 20. The actuator 36 has a range of movement including between the upper, non-cooking position of the upper platen 16 and the cooking position of the upper platen 16. The actuator 36 may be located in the mechanism housing 19 and the arm arrangement 20 may be located at least partially in the mechanism housing 19. As discussed below, the actuator 36 may have a full range of movement beyond the upper and cooking positions such that calibration thereof is necessary. The arm arrangement 20 comprises at least one arm 22 extending from the main body 12, particularly the mechanism housing 19, to a pivotal connection 28 with the upper platen assembly 15. The at least one arm 22 is adjustable, such as by the actuator 36, so as to raise and lower the upper platen 16 relative to the lower plate 14 between the upper position and cooking position. The arm arrangement 20 and stop arrangement 30 are predominantly located between the pivotal connection 28 and appliance rear 102. The upper platen assembly 15 is biased to pivot about the pivotal connection 28 into the stop arrangement 30. The centre of mass of the upper platen assembly 15 may be (a) between the pivotal connection 28 and the front of the upper platen assembly 15, and / or (b) on the opposing side of the pivotal connection 28 to most of the arm arrangement 20. Hence the pivotal connection 28 with the upper platen assembly 15 may be offset from the centre thereof, being closer to the rear than front of the upper platen assembly 15. The pivotal connection 28 may be separated at a pivot height perpendicular from the upper platen, the pivot height being at least 5 cm. The pivotal connection 28 may in particular be with the upper housing 50 of the upper platen assembly 15 as illustrated, although it may be to the platen body 17 or otherwise connected to the platen body 17. The pivotal connection 28 may comprise, at end of the at least one arm arrangement 20 and mounted to or within the upper housing 50, at least one rod (not shown) extending into a bearing or other aperture in which the at least one rod can rotate, providing the pivoting movement. The arm arrangement 20 preferably comprises a first arm 22 extending between first and second ends 21,23, the first end 21 being mounted to or in the mechanism housing 19. The first arm 22 is moveable perpendicular to the lower plate 14. The arm arrangement 20 may comprise a second arm 24 extending non-parallel and / or non-perpendicular to and from the second end 23 of the first arm 22 to the pivotal connection 28 with the upper platen assembly 15. The terms “perpendicular” and “parallel” in the present disclosure refer to components being approximately perpendicular and parallel to one another by up to 5°, or up to 10°. The second arm 24 may extend from the second end 23 of the first arm 22 at an angle less than 90° relative to the first arm 14. The first and second arms 22, 24 may be integrally formed as illustrated. The movement mechanism 18 may comprise a first arm arrangement 20 and a second arm arrangement 40 extending from the main body 12 to the upper platen assembly 15. The first arm arrangement 20 is proximal to the first appliance side 104 and first side of the upper platen assembly 15 and the second arm arrangement 40 is proximal to the second appliance side 103 and second side of the upper platen assembly 15. Each arm arrangement 20, 40 is formed as described above, comprising first and second arms 22, 24, wherein each second arm 24 is pivotally connected to the upper platen 16. The first arm arrangement 20 and the second arm arrangement 40 may be connected by a support bar 64 extending therebetween, such as perpendicular to both arm arrangements 20, 40. The stop arrangement 30 preferably comprises a first stop 32 for abutting the upper platen assembly 15 when the upper platen 16 is between the intermediate position and the upper position. The stop arrangement 30 also preferably comprises a second stop 34 for abutting the upper platen assembly 15 between an intermediate position (Figures 3 and 4) and the cooking position. The first stop 32 is configured to maintain the upper platen 16 non-parallel to the lower plate 14 when the upper platen assembly 15 is moved between the intermediate position and the upper position, and / or allow the angle of the upper platen 16 relative to the lower plate 14 to increase when the upper platen assembly 15 is moved from the intermediate position to the upper position. The second stop 34 is configured to maintain the upper platen 16 parallel to the lower plate 14 when the upper platen assembly 15 is moved between the intermediate position and the cooking position. The first and second stops 32, 34 are preferably configured to abut the upper platen assembly 15 between the pivotal connection 28 and the rear of the upper platen assembly 15 and / or on an opposing side of the pivotal connection 28 to the centre of mass of the upper platen assembly 15. The first stop 32 may comprise a guide member 32 extending from and / or fixed relative to the main body 12 for abutting the upper platen 16. The guide member 32 may comprise an elongate body or cantilever extending from the main body 12, such as from the mechanism housing 19, towards the upper platen assembly 15 for contacting the upper platen assembly 15 at a distal end of the guide member 32 to where it is mounted to the main body 12. The guide member 32 may extend parallel to the lower plate 14 from adjacent the appliance rear towards the appliance front. The guide member 32 may comprise a roller 33, which may be located at the distal end as illustrated. The second stop 34 may comprise a branch 34 extending from the arm arrangement 20, preferably from the second arm 24 for abutting the upper platen 16 and limiting the pivoting of the upper platen assembly 15 about the pivotal connection 28. When the movement mechanism 18 comprises two arm arrangements 20, 40, the branch 34 may extend from one or both of the arm arrangements 20, 40. The branch 34 may comprise a generally elongate body extending downwardly, preferably perpendicular to the lower plate 14, from the arm arrangement 20, 40, preferably from the second arm 24, towards the upper platen assembly 15. The length of the guide member 32 and the branch 34 may be selected such that when the upper platen 16 is lowered or raised, only one of the guide member 32 or branch 34 are in contact with the upper platen 16 at a time, except when the upper platen assembly 15 is in the intermediate position. The cooking appliance 10 may further comprise a control arm arrangement 60 extending from the mechanism housing 19 to a user control unit 62. The user control unit 62 may comprise a digital touchscreen display for operation by the user of the cooking appliance 10. The control arm arrangement 60 may be in communication with the actuator 36 such that the control arm arrangement 60 is raised and lowered relative to the lower plate 14 with the raising and lowering of the upper platen assembly 15. The control arm arrangement 60 may be connected to the arm arrangement or arm arrangements 20, 40 by support bar 64. The control arm arrangement 60 may be positioned between the first and second arm arrangements 20, 40. The cooking appliance may further comprise a controller (not shown) configured to control the movement of the at least one arm arrangement 20, 40 by controlling the actuator 36 and preferably configured to receive instructions from and supply data to the user control unit 62. The controller may receive instructions on cooking temperature, cooking time, and / or upper platen height from the user control unit 62 and operate the cooking appliance 10 in accordance with the instructions. The controller may comprise a memory configured to store recipes with preset cooking temperatures, cooking times, and upper platen heights. The controller may be configured to raise and lower the upper platen 16 by issuing instructions to the actuator 36. The controller may be configured time the cooking of the food items and may be configured to regulate the temperatures of the lower plate 14 and upper platen 16 by controlling the heating elements. The controller may be configured to alert the user to the completion of the cooking cycle. When the cooking appliance 10 is not in use, the upper platen 16 is in the cooking position. In use, the user inputs cooking instructions and / or selects a recipe on the user control unit 62. The controller operates the heating elements to heat the upper platen 16 and lower plate 14 to the temperature required by the instructions and / or recipe. Furthermore, the controller may be configured to operate the at least one arm arrangement 20, 40 such that the upper platen 16 and lower plate 14 are separated by a gap, the gap height (i.e. the distance between the upper platen and lower plate 14) being controlled by the controller, preferably in accordance with the cooking instructions and / or recipe. Heating the upper platen 16 and the lower plate 14 before raising the upper platen 16 prevents the user from placing food on the lower plate 14 before the upper platen 16 and lower plate 14 have reached the required temperature and thus ensures the cooking time is accurate to that required by the recipe. When the upper platen 16 and the lower plate 14 have reached the required cooking temperature the upper platen 16 is raised and tilted from the cooking position to the upper position shown in Figure 1. The upper platen 16 is raised by the arm arrangement 20, which is raised by the linear actuator 36. The second stop 34 of the stop arrangement 30 resists the upward torque on the rear of the upper platen 16 and the upper platen 16 raises without tilting. When the first stop 32 comes into contact with the upper platen 16 at its frontmost position it resists the further upward motion of the rear of the upper platen 16 and the arm arrangement 20 continues to raise the upper platen 16. Due to the resistance provided by the first stop 32, the upper platen 16 tilts upwards and away from the lower plate 14 from the cooking position to the upper position until the first stop 32 reaches its rearmost point of contact with the upper platen 16 and the arm arrangement 20 and linear actuator 36 reach the topmost position. In the upper position, the upper platen 16 forms an angle with the lower plate 14 between 30° and 40° such that the user can safely and easily reach the rear of the lower plate 14. The arm arrangements 20, 40 and actuator 36 are in the topmost position, and the stop arrangement 30, preferably the guide member 32, is in contact with the rear of the upper platen 16. The user places the food to be cooked on the lower platen 14. The upper platen assembly 15 is then lowered towards the lower plate 14 by the arm arrangement 18 by controller controlling the actuator 36, in a reverse manoeuvre to that described above. The front of the upper platen assembly 15 is biased to tilt downwardly towards the lower plate 14 as the upper platen 16 is lowered. Such biasing may be due to a downward torque on the front of the upper platen 16 caused by the centre of mass of the pivotal connection 28 being closer to the front of the upper platen assembly 15 than rear. The stop arrangement 30 provides resistance against the upward torque on the rear of the upper platen 16, limiting the pivoting of the upper platen 16 past the cooking position. As the upper platen 16 tilts from the upper position to the cooking position, the point at which the first stop 32 contacts the upper platen 16 moves from a rearmost position to a frontmost position. When the upper platen 16 is parallel to the lower plate 14 the second stop 34 comes into contact with the upper platen 16 and provides the resistance against upward torque on the rear of the upper platen 16 such that the upper platen 16 remains parallel to the lower plate 14 when the upper platen 16 in the cooking position is further lowered towards the lower plate 14. The upper platen 16 remaining parallel to the lower plate 14 allows the food items to be cooked evenly. When the upper platen 16 has reached the gap height above the lower platen 14 required by the user instructions and / or the recipe, the food items therebetween are cooked for a time required by the instructions and / or the recipe. When the cooking time has elapsed, the upper platen 16 is raised and tilted from the cooking position to the upper position as described above. The controller may then alert the user to the completion of the cooking cycle. The cooking appliance 10 may comprise a plurality of lower plates 14, upper platens 16, and movement mechanisms 18 adjacent to one another in a single cooking appliance 10. Each set of lower plates 14 and upper platens 16 may be independently controlled by independent user control units 62. In order to achieve a consistent gap height, the controller is configured to perform a calibration process. The calibration process may be performed periodically, such as daily or every time the cooking appliance is switched on, such that drift from sensors over time can be accounted for and an accurate gap height can continue to be achieved. In embodiments, as best illustrated in Figure 6, the at least one arm arrangement 20, 40, such as the second arm arrangement 40, is configured to be moved by the actuator 36 between first and second calibration positions. The second calibration position is shown in Figure 6. The first and second calibration positions are indicative of maximum and minimum heights of the arm arrangement 20, 40 and actuator 36. The controller may stop the actuator 36 when the first and second calibration positions are reached, thereby implementing the maximum and minimum heights. The cooking appliance 10 comprises at least one sensor 90, 91 connected to, and configured to supply sensor data to, the controller. The at least one sensor 90, 91 is configured to generate sensor data indicative of when the arm arrangement 20, 40 has reached the first and second calibration positions. Thus the at least one sensor 90, 91 may comprise first and second limit switches 90, 91 located at the first and second calibration positions and an arm stop 92 is configured to actuate the first and second limit switches 90, 91 when it reaches the first and second calibration systems. The at least one sensor 90, 91 is also configured to determine the displacement of the actuator 36 when the arm arrangement 20, 40 is moved between the first and second calibration positions. In effect, the sensor data is indicative of the actuating movement by the actuator 36 itself when it is actuated to move the arm arrangement 20, 40 between the first and second calibration positions. The at least one sensor 90, 91 may comprise an encoder (not shown) for generating sensor data indicative of the displacement of the actuator 36. The encoder may determine linear displacement if the actuator 36 is a linear actuator, or angular displacement if the actuator 36 is a motor. In the calibration process, the arm arrangement 20, 40 is moved between the first and second calibration positions with the at least one sensor 90, 91, such as the limit switches 90, 91, determining when the calibration positions are reached. The at least one sensor 90, 91, such as the encoder, determines the displacement by the actuator 36 during the movement between the first and second calibration positions. Since the exact distance between the first and second calibration positions is known, the controller can determine an actuator displacement ratio indicative of the displacement of the actuator 36 per unit of movement of the arm arrangement 20, 40. After the controller has received a desired gap height from a user, or from its memory, the controller can use the actuator displacement ratio to determine the displacement of the actuator 36 necessary in order to achieve the desired gap height. Subsequently, the controller can achieve the desired gap height by operating the actuator 36 to move the arm arrangement 20, 40 such that the lower plate 14 and upper platen 16 are separated by the desired gap height. The controller utilises the ratio to determine the displacement of the actuator 36 required to achieve the desired gap height. The controller utilises the sensor data from the at least one sensor 90, 91, such as the encoder, in a feedback loop to monitor the displacement of the actuator 36 until it reaches the displacement necessary to achieve the desired gap height. Such a method enables the desired gap height to be achieved accurately and based upon an input desired gap height from a user.

Claims

1. A cooking appliance comprising:an upper platen assembly comprising an upper platen;a lower plate for receiving food items and mounted to a main body; anda movement mechanism for adjusting the height and angle of the upper platen assembly relative to the lower plate, wherein the movement mechanism comprises:an arm arrangement comprising at least one arm extending from the main body to a pivotal connection with the upper platen assembly, wherein the at least one arm is adjustable so as to raise and lower the upper platen assembly relative to the lower plate between an upper position and a cooking position; anda stop arrangement for abutting the upper platen assembly and limiting pivoting of the upper platen assembly relative to the arm arrangement around the pivotal connection such that in the upper position the upper platen is non-parallel to the lower plate and in the cooking position the upper platen is parallel to the lower plate.

2. A cooking appliance as claimed in claim 1 wherein, in the cooking position, the upper platen is parallel to the lower plate by an angle therebetween being less than 10°.

3. A cooking appliance as claimed in claim 1 wherein the raising and lowering of the upper platen assembly comprises moving the upper platen assembly perpendicular to the lower plate.

4. A cooking appliance as claimed in claim 1 wherein the arm arrangement comprises: a first arm extending between first and second ends, the first end beingmounted to or in the main body, wherein the first arm is moveable perpendicular to the lower plate; anda second arm, wherein the second arm extends from thesecond end of the first arm to a pivotal connection with the upper platen assembly, the first and second arms being non-parallel and / or non-perpendicular to one another.

5. A cooking appliance as claimed in any preceding claim comprising a linear actuator for moving the arm arrangement.

6. A cooking appliance as claimed in any preceding claim wherein the cooking appliance comprises at least two arm arrangements.

7. A cooking appliance as claimed in any preceding claim wherein the arm arrangement is pivotally connected to the upper platen assembly by the pivotal connection such that the upper platen assembly is biased to pivot about the pivotal connection into the stop arrangement.

8. A cooking appliance as claimed in any preceding claim wherein:the pivotal connection is positioned offset from the centre of the upper platen and / or separated at a pivot height from the upper platen;a centre of mass of the upper platen assembly is between the pivotal connection and a front of the upper platen assembly; and / orthe pivotal connection is to an upper housing of the upper platen assembly.

9. A cooking appliance as claimed in any preceding claim wherein the stop arrangement comprises:a first stop for abutting the upper platen assembly when the upper platen is between the intermediate position and the upper position; anda second stop for abutting the upper platen assembly when the upper platen assembly is between an intermediate position and the cooking position.

10. A cooking appliance as claimed in claim 9 wherein:the first stop is configured to maintain the upper platen non-parallel to the lower plate when the upper platen assembly is moved between the intermediate position and the upper position and / or allow the angle of the upper platen relative to the lower plate to increase when the upper platen assembly is moved from the intermediate position to the upper position; and / orthe second stop is configured to maintain the upper platen parallel to the lower plate when the upper platen assembly is moved between the intermediate position and the cooking position.

11. A cooking appliance as claimed in claim 9 or claim 10 wherein:the first stop comprises a guide member extending from and / or fixed relative to the main body for abutting the upper platen; and / orthe second stop comprises a branch extending from the arm arrangement for abutting the upper platen assembly and limiting pivoting of the upper platen assembly about the pivotal connection.

12. A cooking appliance as claimed in any one of claims 9 to 11 wherein the first and second stops are configured to abut the upper platen assembly between the pivotal connection and a rear of the upper platen assembly and / or on an opposing side of the pivotal connection to the centre of mass of the upper platen assembly.

13. A cooking appliance as claimed in any preceding claim comprising electric heating elements for heating the upper platen and lower plate.

14. A cooking appliance as claimed in any preceding claim comprising a control arm arrangement wherein the control arm arrangement comprises a control unit for a user to input instructions and / or select a recipe, the instructions and / or recipe being configured to cause the arm arrangement to move.

15. A cooking appliance as claimed in any preceding claim comprising a controller configured to receive instructions on cooking temperature, cooking time, and upper platen height and operate the cooking appliance in accordance with the instructions.

16. A cooking appliance as claimed in claim 12 wherein the controller comprises a memory for storing recipes with preset cooking temperatures, cooking times, and upper platen heights.

17. A cooking appliance as claimed in any preceding claim comprising a plurality of adjacent upper platen assemblies and lower plates.

18. A method of operating a cooking appliance, the cooking appliance comprising: an upper platen assembly comprising an upper platen;a lower plate for receiving food items and mounted to a main body; anda movement mechanism for adjusting the height and angle of the upper platen assembly relative to the lower plate, wherein the movement mechanism comprises:an arm arrangement comprising at least one arm extending from the main body to a pivotal connection with the upper platen assembly; anda stop arrangement for abutting the upper platen assembly, wherein the method comprises adjusting the at least one arm so as to raise and / or lower the upper platen assembly relative to the lower plate between an upper position and a cooking position, wherein during the adjustment the stop arrangement limits pivoting of the upper platen assembly relative to the arm arrangement around the pivotal connection such that in the upper position the upper platen is non-parallel to the lower plate and in the cooking position the upper platen is parallel to the lower plate.

19. A method according to claim 18 wherein the stop arrangement comprises first and second stops and the method comprises:limiting pivoting of the upper platen assembly by the second stop abutting the upper platen assembly between the intermediate position and the upper position; andlimiting pivoting of the upper platen assembly by the first stop abutting the upper platen assembly between an intermediate position and the cooking position.

20. A method according to claim 19 wherein the method comprises:maintaining, by the first stop, the upper platen non-parallel to the lower plate when moving the upper platen assembly between the intermediate position and the upper position and / or increasing, by the first stop, the angle of the upper platen relative to the lower plate when moving the upper platen assembly from the intermediate position to the upper position; and / ormaintaining, by the second stop, the upper platen parallel to the lower plate when moving the upper platen assembly between the intermediate position and the cooking position.

21. A method according to any one of claims 18 to 20, wherein the cooking appliance comprises a controller for adjusting the arm arrangement, the method comprising:receiving instructions and / or a selected recipe from the controller;heating the upper platen and lower plate according to the instructions and / or recipe;raising and tilting the upper platen from the cooking position to the upper position for receiving food items on the lower plate;lowering and tilting the upper platen assembly into the cooking position from the upper position;setting a gap height between the upper platen and lower plate in the cooking position in accordance with the instructions and / or recipe; timing the cooking of the food items according to the instructions and / or recipe; andraising and tilting the upper platen assembly from the cooking position into the upper position.

22. A method of operating a cooking appliance comprising, by a controller:performing a calibration process comprising:operating an actuator to move an arm arrangement between first and second calibration positions, the arm arrangement being for moving an upper platen assembly relative to a lower plate for receiving food items therebetween;receiving sensor data from at least one sensor indicative of:the arm arrangement reaching first and second calibration positions; andthe displacement of the actuator when the arm arrangement is moved between the first and second calibration positions; anddetermining, based upon the sensor data, an actuator displacement ratio indicative of the displacement of the actuator per unit of movement of the arm arrangement;determining a desired gap height between the lower plate and an upper platen of the upper platen assembly;operating, based upon the actuator displacement ratio, the actuator to move the arm arrangement such that the lower plate and upper platen are separated by the desired gap height.

23. The method of claim 22 wherein the at least one sensor comprises first and second limit switches configured to generate sensor data indicative of the arm arrangement reaching the first and second calibration positions respectively.

24. The method of claim 22 or claim 23 wherein the at least one sensor comprises an encoder for generating sensor data indicative of the displacement of the actuator when the arm arrangement is moved between the first and second calibration positions.

25. A cooking appliance comprising:an arm arrangement being for moving an upper platen assembly relative to a lower plate for receiving food items therebetween;an actuator for moving the arm arrangement;at least one sensor; anda controller configured to:perform a calibration process comprising:operating the actuator to move the arm arrangement between first and second calibration position;receiving sensor data from the at least one sensor indicative of:the arm arrangement reaching first and second calibration positions; andthe displacement of the actuator when the arm arrangement is moved between the first and second calibration positions; anddetermine, based upon the sensor data, an actuator displacement ratio indicative of the displacement of the actuator per unit of movement of the arm arrangement;determine a desired gap height between the lower plate and an upper platen of the upper platen assembly;operate, based upon the actuator displacement ratio, the actuator to move the arm arrangement such that the lower plate and upper platen are separated by the desired gap height.

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