GB2276243A

GB2276243A - Cooking appliance

Info

Publication number: GB2276243A
Application number: GB9403431A
Authority: GB
Inventors: Lodewijk Josef Theofiel Boyen
Original assignee: NOVA ELECTRO INT
Current assignee: NOVA ELECTRO INT
Priority date: 1993-02-23
Filing date: 1994-02-23
Publication date: 1994-09-21
Anticipated expiration: 2014-02-23
Also published as: GB2276243B; GB9403431D0; BE1006744A5; ITMI940314A1; FR2701827B1; IT1296802B1; FR2701827A1; ITMI940314A0

Abstract

In a cooking appliance comprising a vessel intended to contain fat or oil in which food can be fried and heated by an electrical resistance (1, Fig. 1) which is connecter to a supply via a temperature control element (2) so that the power input is reduced as soon as the oil or fat temperature exceeds a given temperature, a system for determining the quality of the oil or fat comprises a means (5, 6) for measuring or evaluating the power consumption at least during the cooking of food. The appliance also comprises a means which, in the absence of power consumption by the resistance (1), does not activate or only partially activated said system. As shown the means (5, 6) comprises a motor which drives an indicator wheel and which is connected across the supply or in parallel with the heater (1) by a switch (7); the latter is controlled by a timer (5). In an alternative embodiment there are two heating elements (1a, 1b, Fig. 4), element (1b) being switched off by a second temperature control device (2b) when a given temperature (e.g. 170 DEG C) is reached. An arrangement is also described having an indicator wheel driven at a lower or a higher speed by one of two motors (5a, b Fig. 2 not shown) in dependance on the fat/oil temperature. <IMAGE>

Description

COOKING APPLIANCE The present invention relates to a cooking appliance comprising a vessel intended to contain fat or oil in which food can be fried. Said appliance comprises an electrical resistance which is intended to heat said fat or oil and which is connected to a-temperature-control system so that the power input is reduced as soon as the oil or fat temperature exceeds a given temperature.

Cooking appliances of the fryer type are currently provided with a system for determining the quality of the oil or fat so as to obviate health problems and/or problems in respect of the fried products (organoleptic property).

According to one system which is installed in a fryer, only the cooking time is measured in a uniform manner.

This system is generally acceptable for determining the quality of an oil which is used frequently over a short period of time, however, it does not take into account factors such as an addition of fresh oil, humidity during cooking, temperature during cooking..., namely parameters which influence the loss of the properties of the oil.

Experience in testing and by users has shown that the simple integration of time and temperature brought about disadvantages and did not solely provide accurate information under "standard" cooking conditions. The information in respect of oil quality can be very inaccurate depending on the oils, fried foods rich in protein, being situated in poorly lit and cold places during storage, the addition of oil, etc...

In another system simply the number of portions cooked or being cooked, or the heating number of the oil bath is measured. In a system of this type the heating time and/or weight of the portions is not taken into account in any way.

On the basis of various research projects it has been observed that, by measuring or evaluating the power consumption of the fryer, particularly power consumption while food is being cooked in the oil, it was possible to determine or evaluate the degradation of the oil.

The fryer according to the invention comprises a vessel intended to contain the fat or oil in which food can be fried, said appliance comprising: * an electrical resistance which is intended to heat said fat or oil and which is connected to a temperature control system so that the power input is reduced as soon as the oil or fat temperature exceeds a given temperature, and * a system for determining the quality of the oil or fat.

This system for determining the quality of the oil or fat comprises a means for measuring or evaluating at least the power consumption during the cooking of food, the appliance further comprising a means which, in the absence of power consumption by a resistance (i.e. by the resistance if there is only one or by one of the resistances if there are several), does not activate or only partially activates said system.

Preferably, if the appliance comprises a plurality of resistances, the means for measuring power measures or evaluates the power consumption of all the resistances.

According to one embodiment, the system for determining the quality of oil or fat comprises an electric circuit, the two elements of which are connected to a temperature-measuring or control system so that for oil or fat temperatures above a given temperature one of said elements operates in such a way that the measurement of power consumption is evaluated to be higher than the measurement of power consumption for temperatures below said given temperature.

According to another embodiment, the appliance comprises an electric circuit, in which two resistances and a motor are connected in parallel, a temperature-measuring or control system which disconnects one resistance as soon as the oil or fat temperature is above a given temperature.

Advantageously, the electric circuit comprises two temperature-measuring or control systems, the first of which disconnects one resistance as soon as the oil or fat temperature exceeds a given temperature, whereas the second one disconnects the other resistance or both resistances as soon as the oil or fat temperature is above a given maximum temperature.

For example, the first measuring or control system, such as a thermostat or bimetallic strip, disconnects one resistance as soon as the oil or fat temperature is above 150 C, preferably above 170-175"C, whereas the second system disconnects the resistances as soon as the oil or fat temperature is above a maximum admissible cooking temperature (for example, a temperature of between 1800C and 220"C.

In another embodiment, the appliance comprises an electric circuit comprising one resistance and two motors, each of which are connected in parallel with the resistance, a first temperature-measuring or control system disconnecting a first motor as soon as the oil or fat temperature is above a given temperature, whereas one temperature-measuring or control system connects the second motor when the oil or fat temperature is above said given temperature, said first motor driving a measuring system at a first given speed, whereas the second motor drives said system at a speed higher than said first given speed.

According to one embodiment, in which said appliance is provided with a device for extracting fumes and/or vapours from the vessel and for directing these fumes and/or vapours into a casing containing water to cool the fumes and/or to condense the vapours at least partly, the system for determining the quality of the oil or fat comprises a means for measuring the weight and/or temperature of the water contained in the casing.

According to one feature of this embodiment, the system for determining the quality of the oil or fat comprises a means for measuring the operating time, a means for measuring the weight and/or temperature of the water in the casing.

Preferably, the system for determining the quality of the oil or fat comprises a chip in which the degradation of the oil is evaluated in accordance with the formula: degradation of the oil: f (operating time) + f !difference in temperature of the water in the casing and/or difference in weight of the water in the casing).

In the embodiments in which the means for evaluating or measuring power consumption comprises a motor, said motor advantageously acts on a member so as to move the basket (intended to contain the food) in the vessel, in particular so as raise the basket at the end of the cooking time.

For example, the motor drives two gearwheels, the first of which is connected to the system for determining the quality of the oil or fat, whereas the second gearwheel is intended to be connected to a third gearwheel for raising the basket in the vessel.

Further details and features of the invention will be apparent from the following detailed description made with reference to the accompanying drawings, wherein: - Figure 1 illustrates schematically an electric circuit for controlling the quality of the oil or fat; - Figure 2 illustrates schematically a second electric circuit for controlling the quality of the oil or fat; - Figure 3 shows a detail of the circuit shown in Fig. 2; - Figure 4 illustrates schematically a third electric circuit for controlling the quality of the oil or fat; - Figures 5 and 6 are views partly in section of a fryer provided with a device for raising and lowering the basket in the vessel (Fig. 5: basket lowered;Fig. 6: basket raised); - Figure 7 is a partial side view of the fryer illustrated in Figure 5; - Figures 8 to 11 are views of the mechanism for actuating the basket during its operation; - Figures 12 and 13 are views in section taken along the lines XII-XII and XIII-XIII of the mechanism illustrated in Figure 8 to 10; - Figure 14 is side view taken along the line XIV-XIV of the mechanism in the position shown in Figure 13; - Figures 15 and 16 are views in perspective of the parts of the mechanism.

Figure 1 shows schematically an electric circuit of a fryer. This circuit comprises a resistance 1, a thermostat 2 or bimetallic strip intended to disconnect the resistance 1 when the temperature of the fat or when the temperature of oil or fat is above a given temperature, for example when the oil or fat temperature reaches or exceeds the selected maximum cooking temperature, and a thermal protection device or circuit breaker 3 which interrupts the circuit when required if the thermostat is faulty.

A light 4 for indicating the operation of the resistance and a motor for evaluating the power consumption of the resistance 1 are connected in parallel with the resistance 1.

The motor 5 drives a wheel 6 on which the operating time of the resistance and thus the power consumption by the resistance are indicated. In fact, this wheel 6 acts as a memory, i.e. the wheel 6 takes into consideration the cooking of several portions and the heating stages.

If necessary, a switch can be provided in this circuit. This switch 7 can be actuated, for example, by a timer so as to continue the rotation of the timer 8 until reaching the "0" position. When the timer is in the "0" (starting) position, from the electrical standpoint the switch is in parallel in relation to the heating element 1.

In some embodiments, therefore, it may be advantageous before the end of a cooking stage to supply the motor 5 directly, for example via the switch 7.

Figures 2 and 3 illustrate schematically an embodiment of an electric circuit for determining the quality of an oil or its rate of degradation.

This circuit comprises a resistance 1, which is intended to heat the oil or fat and which is connected to a thermostat 2 intended to disconnect the resistance 1 when the oil or fat temperature reaches the desired cooking temperature, a light 4 connected in parallel with the resistance 1 so as to indicate the operation of the resistance and a thermal protection device 3, in case the thermostat 2 does not interrupt the circuit at the required time.

Two synchronous motors 5a, 5b are connected in parallel with the resistance 1 and the thermostat 2. A switch 7, which is actuated as a function of the oil or fat temperature, allows the supply of power to the motor 5b when the oil or fat temperature is below a predetermined temperature (for example 1500C, preferably 175"C) and supply of power to the motor 5a when the oil or fat temperature is above said given temperature.

Toothed discs 52a, 52b are mounted on the spindles 51a, 51b of the motors 5a, 5b, which discs act on a toothed disc 53 for the measuring the oil degradation. This measuring disc is mounted on a spindle 54 and can be driven either by the toothed disc 52a or by the toothed disc 52b.

The motor 5b imparts rotating motion to its spindle 51b in a clockwise direction, whereas the motor 5a imparts rotating motion to its spindle 51a in an anticlockwise direction. The speed of rotation of the motor spindles is identical.

However, since the diameter D of the toothed disc 52b is smaller than the diameter d of the toothed disc 52a, the motor 5b imparts rotating motion to the measuring disc 53 at a predetermined speed which is lower than the speed at which the measuring disc 53 is driven by the motor 5a.

For example, the ratio d/D is between 1.5 and 3 (preferably, about 2).

Figure 4 shows a third embodiment of an electric circuit of a fryer according to the invention.

This circuit comprises two resistances la, lb which are connected in parallel and two thermostats or bimetallic strips 2a, 2b. A first thermostat or bimetallic strip 2b serves to disconnect the resistance ib (i.e. no longer supply it with current) as soon as the oil or fat temperature reaches a temperature of 170-175"C, whereas the second thermostat or bimetallic strip 2a serves to disconnect the resistance la as soon as the oil or fat temperature reaches the desired cooking temperature, for example 1900C.

The circuit shown in Figure 1 comprises a circuit breaker or thermal cutout 3, a warning light 4 for indicating the operation of the resistance la or lb and a motor 5 for determining or evaluating any power consumption or the degradation of the oil.

The motor is a synchronous motor which can be used to move the basket 10 in the vessel 11, for example for raising the basket 10 after the cooking time (see Figure 5) or lowering the basket 10 (see Figure 6). The movement of the basket is brought about by a mechanism such as that described in EP 0149856.

The mechanism used in Figure 5 comprises an arm 13 which is mounted at the end of a spindle 12 which can be drive by the motor 5. The free end of the arm 13 has a pin 14 which acts on a member or part of an intermediate member 15 which extends between the handle 16 and the system 17 which carries the basket.

By rotation of the arm 13, the intermediate member slides in a support plate 18 (arrow A), whereupon the basket 10 is raised or lowered in the vessel 11.

The fryer is advantageously provided with a timer 19 which can be controlled by a knob 20. The positions of the knob are cooking (duration from 0 to 24 minutes, for example), raising the basket (arrow 21) and lowering the basket (arrow 22).

The fryer has a window 23 through which the rate of degradation of the oil can be read on the measuring system 24.

The knob 20 for setting the cooking time is driven by a wheel 25. The knob 20 is of substantially cylindrical shape and is provided on one face with teeth 26 which extend substantially in a direction parallel to the axis of rotation 27 of the wheel 25. The wheels 26 are disposed annularly side by side.

The teeth 26 serve to co-operate with the teeth 28 of the wheel 25 so as to enable the knob 20 to rotate when the wheel 25 rotates.

A spring 29, which urges the wheel 25 towards the knob 20, makes it possible for the knob 20 to be turned in relation to the wheel 25, for example so as to select a given cooking time.

When the knob 20 is turned in relation to the wheel 25, the teeth 26 slide over the teeth 28, whereupon the wheel 25 is then displaced against the action of the spring 29 (spring B).

The motor 5 drives a spindle 30, on which are mounted a worm gear 31 and a gearwheel 32. The motor 5 is connected in parallel with the resistance la (see Figure 4). The worm gear 31 co-operates with a gearwheel which is provided with a small gearwheel 34 which drives the wheel 25. The gearwheel 25 is provided with a gearwheel 35 which acts on a wheel 37 via gearwheels 36a, 36b. This wheel serves to indicate the rate of oil degradation and can rotate along its spindle 40.

The gearwheel 32 is intended to co-operate either with a gearwheel 38 or with a gearwheel 39. These gearwheels 38, 39 each have a cutaway portion 38a, 39a; said portions are offset by 1800 in relation to one another and they ensure that only one gearwheel 38, 39 engages with the gearwheel 32 and that, after rotation of one gearwheel until its cutaway portion arrives in the vicinity of the wheel 32 or is turned towards the wheel 32, the gearwheels 38, 39 are not driven (i.e. the gearwheel 32 can rotate freely, whereas, owing to the non-rotation of the gearwheels 38, 39, the position of the arm 13 and thus of the basket in the vessel can be maintained).

After the upward movement of the basket, the knob 20 no longer has to be driven by the wheel 25. For this to be achieved, it must be possible for the knob 20 to be moved apart from the wheel 25 so that the teeth 26 and 28 no longer engage in one another.

The knob 20 is provided with a spindle 40 which is engaged partly in an opening in the wheel 25. A spring 43 extends between the knob 20 and the wheel 25, so that a force is exerted against a first side of the knob so as to move the knob 20 away from the wheel 25.

A peg 41, which is provided on a wall 42 of the fryer, exerts a force or load against a second side of the knob 20, opposite said first side. The second side has a slot 421 in which the peg can be engaged. When the peg is engaged in said slot the knob 20 is moved away from the wheel 25 by means of the spring 43.

The control of the gearwheels 38, 39 relative to the gearwheel 32 is carried out by means of a V-shaped member 44, said member being able to rotate about a spindle 45 and being made of a resilient material. One end of the member 44 is engaged in a recess 46 which is disposed between the gearwheels 38, 39, whereas the other end of the member 44 contacts the annular side of the knob 20. The knob 20 is provided with a cam 47 which controls the V-shaped member 44.

The slot 421 has an inclined bottom to facilitate the sliding of the peg 41 out of said slot.

The mode of operation of the mechanism will now be described in the following: In Figure 8, the arm 13 is in a position in which the basket 10 is situated in the vicinity of the bottom of the vessel 11. The motor 5 drives the worm gear 31 so that the gearwheel 25 (and thus the wheel 37) and the knob 20 are caused to rotate (arrow 48).

By rotation of the knob 20 the cam 47 contacts the Vshaped member (Figure 9) and a force F is exerted so that the gearwheel 38 engages with the gearwheel 32 (the force F is greater than the force F1 of the spring 100).

The gearwheel 38 is then driven until its cutaway portion 38a is situated in the vicinity of the gearwheel 32.

The rotation of the gearwheel 38 induces the rotation of the arm 13 and an upward movement of the basket 10 in the vessel 11 (see Figure 10).

With a view to cooking another portion of fried food, the user has to turn the knob 20 so as to withdraw the peg 41 from the slot (position in Figure 10). As a result of the rotation of the knob 20 the gearwheel 39 is brought into engagement with the gearwheel 32 by means of the spring 100, so that the gearwheel 39 is engaged and so that the basket is moved downwards (Figure 11). The drive of the wheel 39a is provided in the vicinity of the gearwheel 32.

The user can set the cooking time by turning the knob 20 in relation to the wheel 24.

Tests have been carried out to compare the performance of the electric circuit according to the invention in relation to the optimum values.

The first circuit tested is a circuit according to Figure 1, in which the power of the resistance (1) is 2000 W, whereas the second circuit is a circuit according to Figure 4, in which the power of each of the resistances (la, lb) is 1000 W.

The thermostat 2, 2a is set to 1900C, whereas the thermostat 2b is set to 175"C.

For these tests 500 g portions of fried food are heated in accordance with the following procedure: 1. heating the oil - cooking a portion - cooling, etc.

2. heating the oil - cooking a portion - cooking a portion - cooling, etc.

3. heating the oil - cooking a portion - cooking a portion - cooking a portion - cooling, etc.

4. heating the oil - cooking portions one after the other.

The degradation of the oil is also measured during its heating to a constant temperature of respectively 150"C and 1900C.

In the circuit in Figure 1 the control wheel is turned through 188 minutes, whereas in the circuit in Figure the control wheel is turned through 200 minutes.

The results of these tests are set out in the following tables:

II I I 1 Number of portions which can Optimum value be cooked until the message according to "oil not to be reused" chemical appears analysis TEST No. CIRCUIT 1 CIRCUIT 2 I 1 11-12 11-12 12 I 2 15-16 15-16 15 l 3 17-18 17-18 17 4 1 22-23 21-22 22 CONTINUOUS HEATING

at 1500C at 1900C No. of Optimum No. of Optimum hours hours until the until the message message "oil not "oil not to be to be reused" reused" appears appears Circuit 30-31 32 No. 1 Circuit 32-33 32 10-11 10 No. 2 I It will be noted that the results measured correspond very well to the optimum values, in particular for circuit No. 2.

Claims

1. A cooking appliance comprising a vessel intended to contain fat or oil in which food can be fried, said appliance comprising an electrical resistance, which is intended to heat said fat or oil and which is connected to a temperature-control system so that the power input is reduced as soon as the oil or fat temperature exceeds a given temperature, and a system for determining the quality of the oil or fat, wherein said system for determining the quality of the oil or fat comprises a means for measuring or evaluating at least the power consumption during the cooking of food and wherein the appliance comprises a means which, in the absence of power consumption by a resistance, does not activate or only partially activates said system.

2. Appliance according to claim 1, wherein the system for determining the quality of oil or fat comprises an electric circuit, the two elements of which are connected to a temperature-measuring or control system so that for oil or fat temperatures above a given temperature one of said elements operates in such a way that the evaluation of power consumption is higher than that of the measurement of power consumption for temperatures below said given temperature.

3. Appliance according to claim 1 or 2, wherein it comprises an electric circuit, in which two resistances and a motor are connected in parallel, a temperature-measuring or control system which disconnects one resistance as soon as the oil or fat temperature is above a given temperature.

4. Appliance according to claim 3, wherein the electric circuit comprises two temperature-measuring or control systems, the first of which disconnects one resistance as soon as the oil or fat temperature exceeds a given temperature, whereas the second one disconnects the other resistance or both resistances as soon as the oil or fat temperature is above a given maximum temperature.

5. Appliance according to claim 1, wherein it comprises an electric circuit comprising one resistance and two motors, each of which are connected in parallel with the resistance, wherein a first temperature-measuring or control system disconnects a first motor as soon as the oil or fat temperature is above a given temperature, whereas one temperature-measuring or control system connects the second motor when the oil or fat temperature is above said given temperature, said first motor driving a measuring system at a first given speed, whereas the second motor drives said system at a speed higher than said first given speed.

6. Appliance according to claim 1 or 2, said appliance being provided with a device for extracting fumes and/or vapours from the vessel and for directing these fumes and/or vapours into a casing containing water to cool the fumes and/or to condense the vapours at least partly, wherein the system for determining the quality of the oil or fat comprises a means for measuring the weight and/or temperature of the water contained in the casing.

7. Appliance according to claim 6, wherein the system for determining the quality of the oil or fat comprises a means for measuring the operating time, a means for measuring the weight and/or temperature of the water in the casing.

8. Appliance according to claim 7, wherein the system for determining the quality of the oil or fat comprises a chip in which the degradation of the oil is evaluated in accordance with the formula: degradation of the oil: f (operating time) + f (difference in temperature of the water in the casing and/or difference in weight of the water in the casing).

9. Appliance according to claim 7 or 8, wherein the difference in weight of water in the casing is measured by a pressure-measuring system.

10. Appliance according to any one of claims 3 to 5, wherein the motor actuates a member so as to move a basket in the vessel, in particular so as raise the basket at the end of cooking.

11. Appliance according to claim 10, wherein the motor drives two gearwheels, the first of which is connected to the system for determining the quality of the oil or fat, whereas the second gearwheel is intended to be connected to a third gearwheel for raising the basket in the vessel.

12. Appliance according to claim 11, wherein the first gearwheel drives a cam which acts on a member, the latter acting on the third gearwheel so as to raise the basket in the vessel.

13. A cooking appliance substantiallyh as hereinbefore described with reference to and as illustrated in the accompanying drawings.