The present invention relates to deep fat fryers.

In conventional deep fat fryers, food to be cooked is placed within a basket which is placed within a container, so that the basket is immersed in cooking oil to a depth of several inches. Heating means is provided to heat the oil and thereby cook the food. After cooking, the basket is removed from the oil, allowing oil to drain from the food under gravity. However, significant amounts of oil remain on the food and the high fat content of foods fried in this manner is detrimental to a healthy diet.

According to one aspect of the present invention, a deep fat fryer comprises a container, a basket located in the container, the basket being drivingly mounted on a spindle extending vertically within the container, drive means being provided for rotation of the spindle, means being provided to cause the basket to move axially of the spindle from a lower position to an upper position upon rotation of the spindle and to rotate with the spindle when in its upper position.

With the deep fat fryer according to the invention, the container is filled with oil to a predetermined level, so that the basket in its lower position will be immersed in the oil and the food located in the basket may be cooked in conventional manner. When the food is cooked, the spindle may be rotated to lift the basket to the upper position which is clear of the oil, so that oil will drain from the food . The basket may then be spun on the spindle to centrifuge excess oil from the food, the excess oil draining back into the lower part of the container.

According to a preferred embodiment of the invention, the spindle is provided with a screw thread. A corresponding screw thread or other formation on the basket engages the screw thread on the spindie, so that

upon rotation of the spindle, the basket will move axially along the spindle from the lower position to the upper position. Rotation of the basket during this axial movement will be inhibited by the inertia of the basket and drag of the cooking oil. Alternatively, stop means may be provided to positively prevent rotation of the basket during axial movement. Such stop means may comprise a rib formation on the inner surface of the container which extends up the side of the container and is engaged by a formation on the basket as it moves from its lower to its upper position, the formation on the basket clearing the formation on the container at its upper position, so as to allow the basket to rotate with the spindle.

Stop means is preferably provided at the upper end of the spindle in order to define the upper position of the basket and so that when the stop means is abutted by the basket, rotation of the spindle will then cause the basket to rotate. This stop means may be releasable, in order to permit the basket to be removed from the spindle and container, in order for food to be removed from the basket or for cleaning purposes.

According to an alternative embodiment, the basket may be mounted on the spindle on splines, a track being provided around the inner surface of the container, the track having a lower helical portion with a circular portion at its upper end. A formation on the basket, for example a spigot, engages with the track, so that upon rotation of the spindle interengagement of the formation on the basket with the helical portion of the track will cause the basket to move from its lower position to its upper position. In the upper position, the formation on the basket will engage the circular portion of the track permitting the basket to rotate with the spindle.

Also, according to a preferred embodiment, releasable means is provided for retaining the basket at its upper position when the spindle is not rotating. In this manner, after excess fat has been removed from the

food and the spindle stopped, the basket will not fall back down into the oil before the food has been removed . This may be achieved by using a thread formation which tightens at the upper position. Alternatively, spring loaded latching means, for example a spring loaded ball which engages in a groove in the spindle may be used. Such means may be released manually in order to allow the basket to be lowered back into the oil. Alternatively, means may be provided for reversing rotation of the spindle so that the basket is driven downwardly.

Preferably the spindle is driven by means of an electric motor. The electric motor may be mounted in the base of the container, a suitable sealing means being provided to prevent leakage of oil along the spindle. Alternatively, the motor may be provided on a lid for the container, a suitable drive connection between the motor and spindle being provided to permit the lid to be opened and closed.

The motor is preferably variable speed, so that different foods may be spun at speeds appropriate to separate oil from the food without causing the food to break up. The motor may also be used to rotate the basket in its lowered position, in order to assist the cooking process. Where inertia of the basket and drag are relied upon to cause axial movement of the basket, rotation at the lower position may be achieved by using the slower speeds during the cooking process. Alternatively, stop means to prevent rotation of the basket at the lower position may be disengageable.

The lid of the container may be fitted with a safety switch which will disable the motor when the lid is open and/or which will prevent opening of the lid when the basket is being spun.

A trap may be provided around the periphery of the container above the oii level, in order to catch debris which may be thrown off the food as it

is spun. The trap will be perforated in order to allow the oil to drain back into the bottom of the container.

The various components of the deep fat fryer disclosed above, which are located within the container, are preferably removable for cleaning purposes.

Heating elements for heating the oil are preferably located in the base of the container. Ballast weights may also be located in the base of the container in order to provide stability of the apparatus during use.

An embodiment of the invention is now described, by way of example only, with reference to the accompanying drawings in which:-

Figure 1 is a diagrammatic side elevation of a deep fat fryer in accordance with the present invention, with the basket in its lower position;

Figure 2 is a view similar to Figure 1 with the basket in its upper position; and

Figure 3 is a view along the line Ill-Ill of Figure 1 .

As illustrated in the accompanying drawings a deep fat fryer has a container 10 with a lid 1 1 .

A spindle 1 2 is mounted coaxially of the container 10 and is drivingly connected to a variable speed electric motor 1 3 located in the base of the container 10. Electric heating elements 1 4 are also located in the base of the container 10. The spindle 1 2 has a screw thread formation 1 6.

A basket 20 has a central hub formation 21 having a screw thread formation 22 which corresponds to and interengages with the thread

formation 1 6 on spindle 1 2, so that rotation of the spindle 1 2 relative to the hub formation 21 will cause the basket 20 to move axially of the spindle 1 2.

A collar 25 is secured to the spindle 1 2 adjacent its lower end to limit downward movement of the basket 20. A second collar 26 is secured to the spindle 1 2 adjacent its upper end. The second collar 26 is releasable to permit the basket 20 to be removed from and replaced on the spindle 1 2.

In use, the container 10 is filled with cooking oil up to the level of line 30. When the basket 20 is in its lower position as illustrated in Figure 1 , the hub formation 21 abuts the collar 25 and the basket 20 is immersed in the oil. The oil is heated by means of heating elements 14 to cook food contained within the basket 20.

When the food is cooked, the spindle 1 2 is rotated by means of motor 1 3. Initially, due to inertia of the basket 20 and drag of the oil, there will be relative rotation between the spindle 1 2 and basket 20 driving the basket 20 axially of the spindle 1 2 and lifting it clear of the oil. When the hub formation 21 abuts collar 26 the basket will spin with the spindle 1 2, so that excess oil is centrifuged from the food, the oil draining back into the bottom of the container 1 0. A spring loaded ball catch 35 is provided on the hub formation 21 , this ball catch 35 engaging a circumferential groove 36 on the spindle 1 2 when the hub formation 21 abuts the collar 26. The ball catch 35 will thereby retain the basket 20 in its upper position, when the motor 1 3 is de-energised and the spindle 1 2 stops rotating. The spun dry food may then be removed from the basket 20.

The ball catch 35 may be released to permit the basket 20 to be lowered back down into the oil, by manually rotating the basket 20 counterwise to the normal direction of rotation, thus winding the ball catch 35 back past

the groove 36, or by reversing the motor 13 to drive the basket 20 downwardly.

Switches 40 to 44 are provided on the lid 1 1 , a switch 40 for switching the fryer on and off and switches 41 to 44 for controlling the speed at which the basket 20 is spun, so that the speed may be adjusted appropriately to permit removal of oil from the food while avoiding break¬ up of the food.

The basket 20 may also be rotated at slower speeds while it is in its lower position, in order to assist the cooking process, such slower speeds being incapable of driving the basket 20 axially along the spindle 12 away from the lower position.

In trials of the deep fat fryer described above, when 500 grams of chipped potatoes were cooked and then spun for 30 seconds at 600 rpm, the weight was reduced on average by 20 grams as compared with the same weight of chipped potatoes cooked and drained in the conventional manner. This represents a reduction of about 180 calories per 500 gram portion of chips, when using vegetable oil.