GB1576184A

GB1576184A - Deep fryer especially for domestic use

Info

Publication number: GB1576184A
Application number: GB1271478A
Authority: GB
Original assignee: SEB SA
Current assignee: SEB SA
Priority date: 1977-04-19
Filing date: 1978-03-31
Publication date: 1980-10-01
Also published as: DE2814746A1; DE2814746C3; FR2387625A1; NL7804169A; FR2387625B1; DE2814746B2

Description

(54) A DEEP FRYER, ESPECIALLY FOR DOMESTIC USE (71) We, SEB S.A. a French Body Corporate of 21260 Selongey, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: Deep fryers for frying foods and especially those employed for domestic purposes are arcady known. in a common form of con struction, an appliance of this type comprises a container for a bath of cooking fat such as oil. the bottom of the container being fitted with electric heisting elements (of the built-in resistor type for csamplc). The container is intended to receive a removable basket for the prepared food to be fried and a lid.An appliance of this type calls for many successive handling operations for carrying out the frying operation.

In an improved version of deep fryer, the container is equipped with a lifting and lowering mechanism which can be controlled from the exterior in order to permit lowering of the food-containing basket into the bath and subsequent withdrawal. The container is fitted with a perforated movable lid fitted with a deodorizing filter. Means can also be provided for preventing the water which condenses on the underface of the lid from falling back into the bath and for discharging it to the exterior. In addition, the appliance is advantageously equipped with a thermostat.

In spite of these improvements, the user is obliged to keep a close watch on the thermal evolution of the cooking process and especially to perform manual operations in handling the basket which contains the food to be fried. In consequence, the user is obliged to remain next to the frying appliance during the entire operation and this is a very exacting requirement which tends to inhibit the widespread use of these appliances.

Moreover, the cooking fat undergoes fairly rapid degradation, on the one hand because it is heated to a relatively high temperature of the order of 200"C in accordance with the traditional method of frying and on the other hand by reason of the fact that, in spite of the presence of the lid, the bath is constantly in the presence of air and consequently subject to the danger of oxidation. Finally, the problem created by the gradual accumulation of waste fragments in the bath has not been dealt with and these fragments are therefore not eliminated at the time of renewal of the bath.

It has been sought to remove the waste fragments progressively as they are formed by circulating the oil continuously during the frying operation, this being performed by natural convection, for example, by placing deflectors within the container and causing the oil to pass through the filter. However, these devices call for the use of a substantial volume of cooking fat which does not take part directly in the cooking process but undergoes degradation just as rapidly.

Consideration has also been given to the possibility of reducing the oxidation of the bath by storing it in an evacuated air-tight reservoir and by heating it within this reservoir if necessary. The reservoir is then put into communication with the frying container by means of a system of feed cocks and pumps. A degree of mechanical complexity of this order is conceivable in practice onlyain large installations of the industrial type but not in domestic appliances. Furthermore, automation of these improved designs cannot be achieved in a simple manner.

The present invention is directed to a deep fryer of the bath transfer type which is of particularly simple and reliable construction, is well suited to domestic use and permits practically full automation of all the cooking operations.

In accordance with the invention, there is provided a deep fryer especially for domestic use comprising a heating space for a bath of cooking fat, a cooking space for receiving food in communication with said heating space, and pumping means for displacing the bath from said heating space to said cooking space to put it in contact with the food, characterized in that the pumping means comprise means for applying to a part of the free surface of the bath in the heating space the vapour pressure of a liquid which is immiscible with the bath and which has a predetermined boiling point, said pressure being sufficient to drive the bath from said heating space to said cooking space.

The bath is accordingly driven from one space into the other solely under the action of pressure without employing any mechanical element. This results in more economical construction and cnhanced reliability. At the same time, this arrangement can be adopted in small-sized appliances such as those which are intended for domestic use.

In accordance with one advantageous arrangement of the invention, the heating space and the cooking space are two communicating zones of the same container.

This arrangement which is permitted by the nature of the pumping means employed dispenses with the need for any connecting pipes and achieves a substantial reduction of ovcrall size.

In accordance with a particular feature of the invention, the pumping means comprise a bell-housing, the edge of the skirt of the said housing being maintained in the vicinity of the bottom wall of the container and the end wall of the said bell-housing being located above the normal level of the bath outside the cooking periods. An annular space is formed between the wall of the container and the skirt of the bell-housing. The pumping means further comprise a reservoir which is in communication with the atmospherc of the bell-housing and is thermally coupled with the heating means of the heating space, the said reservoir being intended to receive a predetermined quantity of the aforesaid immiscible liquid whose boiling point at atmospheric pressure corresponds substantially to the temperature at the beginning of the cooking process.

When the temperature attains a sufficient value, the liquid evaporates and the vapour pressure developed within the bell-housing drives the bath between the bottom wall of the container and the edge of the skirt through the annular space towards the cooking space.

It should be noted that, at this instant, if the liquid aforesaid is water, the temperature of the bath is of the order of 100"C, with the result that cooking begins at an appreciably lower temperature than the conventional temperature which is of the order of 200"C.

In accordance with a preferred embodiment of the invention, a filter is placed in the passage between the heating space and the cooking space, with the result that removal of waste fragments produced during the cooking process takes place without any need for a special filtration circuit.

Preferably, the cooking space is located above the heating space and is provided with a removable basket for receiving food.

The downward movement of the bath within the bell-housing under the action of vapour pressure which results in an upward movement within the annular space therefore brings the bath directly into the cooking space. Furthermore, this simple arrangement achieves minimum overall size of the deep fryer.

In an embodiment of the invention, the deep fryer comprises an open-topped external vessel connected by means of a pipe to the reservoir located within the bell-housing in order to enable the user to introduce the necessary quantity of liquid in the said reservoir prior to each utilization of the fryer.

The connecting pipe has an orifice for discharge to the external atmosphere, the said orifice being selectively closable by means of a check-valve fitted with mechanical control means for permitting removal of the vapour and return of the bath into the heating space on completion of the cooking operation.

When the heating space is fitted with heating resistors, the deep fryer advantageously comprises a manual-reset thermostat which is responsive to the temperature of the bath in order to interrupt the heating automatically when this temperature attains a predetermined value.

The value just mentioned can be of the order of 1500C so that the cooking process takes place at a temperature below the conventional temperature and rises progressively. This results in a lower degree of turbulence of the bath, less abundant evolution of gas and consequently less rapid clogging of the deodorizing filter.

In a particular embodiment of the invention, the means for controlling the checkvalve comprise a relay, the coil of the said relay being connected to the thermostat in order to initiate opening of the check-valve at the same time as interruption of the heating.

The automation produced by the thermostat is therefore completed by the automation achieved in the operation of the bath. After having started-up the cooking process, the user need devote no further attention to the operation until the time of withdrawal of the fried food after draining.

In a first alternative form of this embodiment, the open-topped external vessel is located at a level such that, when the said vessel is full of water, the quantity of water introduced in the reservoir located within the bell-housing corresponds substantially to the quantity of water required for the operation.

The level of the vessel with respect to the reservoir is such that these latter form a U-shaped enclosure in which the water stabilizes substantially at the same level in the two legs of the U. The precise quantity of water to be introduced is therefore determined automatically.

In a second alternative form of this embodiment, the external vessel is located at the level of the cooking space and connected to the pipe by means of a cock fitted with mechanical control means connected to the control push-button of the thermostat.

The volume of the vessel corresponds in this instance to the precise quantity of water to be introduced. After filling, the opening of the cock allows the water to flow into the reservoir located within the bell-housing. A single operation of the push-button has the simultaneous effect of initiating the flow of water and turning-on the heating.

In another particular embodiment of the invention, the thermostat comprises a bimetallic strip located in the vicinity of the container wall and so arranged as to cooperate with a system for triggering the heating circuit under the action of thermal expansion of the said bimetallic strip.

In this embodiment, the bimetallic strip produces a mechanical controlling action on the triggering means.

The triggering means aforesaid advantageously comprise a rocker-arm in cooperating relation with a sensitive element of a switch placed in the heating circuit. One end of the said rocker-arm is applied under the action of elastic means against one side of a pivotal bell-crank stop whilst the other side of the said stop cooperates with the bimetallic strip.

As it undergoes deformation, the bimetallic strip causes pivotal displacement of the stop, with the result that the rockerarm withdraws from its bearing position and actuates the switch which cuts-off the heating.

Preferably, the other end of the rockerarm carries the check-valve which serves to close-off the orifice for connecting the pipe to the external atmosphere.

It accordingly follows that the withdrawal of the rocker-arm cuts-off the supply of current while at the same time initiating the discharge of the vapour and the return of the bath into the heating space.

In this embodiment, the open external vessel is again located at the level of the cooking space and connected to the pipe by means of a cock fitted with control means. The said control means are connected to a pushbutton so arranged as to be also in cooperating relation with the rocker-arm in order to reset the thermostat.

In a single operation, the flow of water is initiated and the rocker-arm is returned to its bearing position on the bell-crank stop, thus starting-up the heating and closing the pipe connection to the atmosphere.

In an improved embodiment of the invention, the deep fryer comprises mechanical means for counting the successive cooking operations, the said means being connected to the control push-button.

By virtue of this counting operation, the user can readily decide at which moment it proves necessary to replace the bath or the deodorizing filter cartridge.

In a particular embodiment of the invention, the filter rests partly on the end wall of the bell-housing and is provided with removable means for attachment to the container walls so that the filter can thus be readily removed for cleaning purposes.

The means for attaching the filter are placed in such a manner as to maintain the edge of the skirt of the bell-housing applied against the bottom wall of the container. The said edge is provided with slotted portions in order to establish a communication between the interior of the bell-housing and the exterior.

By virtue of this mode of attachment, it is unnecessary to provide any means for fastening the bell-housing to the container, with the result that the interior of the container has a uniform surface which can easily be cleaned.

In a particular embodiment, the means for attaching the filter comprise at least two resilient strips attached to the filter and extending along the container walls, the said strips being provided with studs for cooperating with cavities formed in the said walls.

The filter and the bell-housing can readily be removed by means of this filterattachment system which can be disassembled instantaneously.

Preferably, the filter is annular and the end wall of the bell-housing has a deformed portion in order to ensure centring of the bellhousing with respect to the filter.

In a further embodiment of the invention, the means for maintaining the bell-housing in position comprise a threaded stud located substantially in the axis of the container and fitted with a nut which is applied against the bell-housing.

By way of alternative, the bell-housing can be provided with movable retaining latches applied against a member which is rigidly fixed to the container and can be a boss formed in the lateral wall or one of the heating resistors located within the container.

In one embodiment, the deep fryer has a lid fitted with a deodorizing filter and the said lid is pivotally mounted on the vessel in a removable manner by means of two resilient clips engaged on the hinge-pin of the said lid.

The lid is advantageously provided with a handle so arranged as to be accessible and to enable the user to place his hand over the lid in such a manner as to ensure that the lid forms a screen between the contents of the container and his hand.

In accordance with an improved embodiment of the invention, the fryer further comprises actuating and time-control means for automatically actuating at the end of a predetermined time interval the different control means which are connected to the pushbutton.

The cooking operation can then be initiated at a precise instant and take place automatically in the absence of the user.

Further properties and advantages of the invention will become apparent from the following detailed description, reference being made to the accompanying drawings which are given by way of example and not in any sense by way of limitation, and in which - Fig. 1 is a longitudinal part-sectional view taken along the line I-I of Fig. 2 and showing a deep fryer in accordance with the invention, in a first embodiment thereof; - Fig. 2 is a sectional view taken along the line II-II of Fig. half-view I; - Fig. 3 is a sectional half-view taken along the line III-III of Fig. 1; - Fig. 4 is a sectional view taken along the line IV-IV of Fig. 3;; - Fig. 5 is a partly cutaway and exploded view in perspective showing the same embodiment - Fig. 6 is a part-sectional view which is similar to Fig. 1 but in perspective - Fig. 7 is a longitudinal sectional view without a lid and showing an alternative form of the first embodiment of a fryer in accordance with the invention, this view being taken along the line VII-VII of Fig. 8; - Fig. 8 is a plan view taken along the line VIII-VIII of Fig. 7;; - Fig. 9 is a part-sectional view taken along the line IX-IX of Fig. 7 - Figs. 10 to 13 are part-sectional views at different levels and taken respectively along the lines X-X, XI-XI, XII-XII of Fig. 9, and along the line XIII-XIII of Figs. 7 and 9 - Fig. 14 is a partially cutaway view in perspective showing the same alternative embodiment - Fig. 15 is a diagrammatic view of the same alternative embodiment and is intended to explain the operation of this lat ter - Fig. 16 is a circuit diagram relating to the two alternative forms of the first embodiment of the invention - Fig. 17 is a partially cutaway view in perspective showing a second embodiment of the invention - Figs. 18 and 19 are diagrams illustrating the operation of the fryer, in particular in the second embodiment - Fig. 20 is a circuit diagram relating to the second embodiment; - Figs. 21 and 22 are part-sectional views of alternative forms of the device for attaching the bell-housing; - Fig. 23 is a part-sectional view showing an alternative mode of attachment of the fryer lid.

Referring now to Figs. 1 to 6, a first embodiment of the deep fryer in accordance with the invention comprises a container 1 which is surmounted by a lid 2 fitted with a deodorizing filter 3 and which rests on a base 4, the said base being secured by means of a screw 5.

There is shown within the container 1 a heating space 6 located beneath a cooking space 7. The said heating space 6 is fitted with a shielded heating resistor 8 which is mounted on the underface of the bottom wall 9 of the container 1 in the example herein described and which is connected to the supply mains by means of suitable wiring (not shown) and terminal connectors 11. The heating space 6 is intended to contain a cooking bath which often consists of oil but can be composed of any suitable cooking fat which is in the liquid state at a temperature below 100"C.

The heating space contains a bell-housing 12 and the edge 13 of the skirt 14 of the said bell-housing rests on the bottom wall 9 of the container 1. Slots 15 are formed in the edge 13 aforesaid in order to provide a communication between the interior and the exterior of the bell-housing 12. The diameter of the bell-housing is appreciably smaller than that of the container 1, with the result that an annular space 16 is formed between these two elements.

An annular plate 17 pierced with holes 18 so as to form a filter rests on the bell-housing 12 and is located coaxially with respect to this latter by means of a die-stamped top wall 19 of the said bell-housing. The external diameter of the filter 17 is only slightly smaller than that of the container 1 in order to cover the annular space 16. The filter 17 is thus placed in the passage between the heating space 6 and the cooking space 7.

Two resilient strips 21 which are fixed on the filter 17 and in diametrically opposite relation are fitted with fastening studs 22 engaged in hollow rivets 23 which are fixed in the wall of the container 1 (as shown in Fig.

2).

It is apparent that the fixing means described above serve to maintain the bellhousing 12 applied against the bottom wall 9 of the container 1 in a substantially centred position.

The cooking space 7 is located above the bell-housing 12 and provided with a removable basket 24 which rests on the bell housing and is intended to contain the food fay A tubular reservoir 26 secured to the bottom wall 9 of the container 1 is located partly within the interior of the bell-housing and partly beneath the bottom wall 9 in order to permit of heating by conduction by means of the resistor 8. The said reservoir is open at the top in order to be in communication with the atmosphere of the bell-housing. To this end, the opening 27 of the said reservoir is located above the normal level of the bath in the cold state as shown by the line 28.

There is fixed on the base 4 an opentopped external vessel 29 which is connected to the reservoir 26 by means of a pipe 31. At the bottom of the vessel 29, a check-valve 32 is capable of either closing-off or freeing the inlet of the pipe 31. The check-valve 32 is controlled mechanically by means of a contact 33 of a relay 34, the coil of which is mounted in series (Fig. 16) with the heating resistor 8 and with a thermostat 35 which is responsive to the temperature of the bath through the metal of the container 1. The said thermostat is so arranged as to break the circuit when the temperature of the bath attains a predetermined value which will be specified hereinafter. Moreover, the thermostat can be reset by means of a pushbutton 36. A signal lamp 37 mounted in parallel indicates whether the appliance is switched-on.

The level of the vessel 29 with respect to the fryer is determined in a manner which will be shown hereinafter.

The operation of the deep fryer which has been described in the foregoing will now be explained.

The heating space 6 having been filled to the level 28 with a bath of cooking fat which melts below 100"C and the basket 24 having been filled with food and placed in position, water is introduced into the open external vessel 29. The thermostat 35 (assuming that this latter has not been set) maintains the heating circuit open and the relay 34 which has not been energized leaves the checkvalve 32 in the open position. The water which is introduced then passes through the pipe 31 into the reservoir 26. Although the atmosphere within the bell-housing is confined, the water level within the reservoir 26 is approximately the same at each instant as the level within the vessel 29.The level of said vessel with respect to the fryer is so determined that, when the vessel is full of water, the reservoir 26 contains the quantity of water which is necessary to ensure operation of the fryer as will be described hereinafter.

When the vessel 29 is completely filled with water, the thermostat 35 is set by means of the push-button 36, thereby supplying current to the heating resistor 8 and at the same time energizing the relay 34. The contact 33 then closes the check-valve 32 which isolates the reservoir 26 from the external atmosphere.

The heating action is such that heat is transmitted by conduction to the reservoir 26 ; when the temperature of the water contained in the said reservoir attains approximately 100"C, the water vaporizes. The vapour pressure is exerted on the free surface of the bath located within the bell-housing and drives the bath through the slots 15 towards the annular space 16 and towards the cooking space 7 in which the bath comes into contact with the food contained in the basket 24.

The cooking process then begins and the temperature of the bath is approximately 100"C. As the heating proceeds, so the heat continues to be transmitted to the bath by conduction through the metal of the container 1 as well as by natural convection within the bath.

When the temperature of the bath attains a predetermined value such as 1500C for example which corresponds to completion of the cooking process, the thermostat 35 opens the circuit, thus interrupting the heating and de-energizing the relay 34. The check-valve 32 opens and allows the steam contained in the bell-housing to escape to the surrounding atmosphere. The bath returns downwards within the heating space 6 and the fried food is allowed to drain while remaining in a hot environment. Within the annular passage, any food fragments which may have escaped from the basket 24 are retained by the filter 17, thus having a contributory effect in preserving the bath.

After cooling has taken place and even if cooling has not been allowed to proceed to completion, and after addition of a further quantity of water within the vessel 29, the appliance is in readiness for a further cooking operation which can be initiated by means of the push-button 36.

Between two operations, it is an easy matter to remove the filter 17 by bending the resilient strips 21 towards the axis of the fryer in order to withdraw the fastening studs 22 from the hollow rivets 23. It is then possible to carry out cleaning of the filter.

When it is necessary to change the cooking bath, the filter 17 is first removed and then bell-housing 12 which is no longer retained can accordingly be withdrawn in order to carry out complete cleaning of the container 1. This cleaning operation is facilitated by the absence of any projection within the container except for the reservoir 26.

The frying appliance thus described accordingly permits of fully automatic operation which does not require any supervision, interruption of the heating and draining of the food being carried out without any manual operation as soon as the cooking is completed. When not in service, the bath is main tained within the bell-housing out of contact with the external atmosphere. Circulation of the bath is obtained by transfer means which are solely static, which are simple and economical to construct and which cannot give rise to any predictable failure. This circulation is also profitably employed in order to carry out filtration of the bath.Finally, by virtue of the progressive temperature rise of the bath, the cooking process employed reduces the rate of evolution of cooking vapour, thus having the effect of extending the period of efficiency of the deodorizing filter.

Referring now to Figs. 7 to 16, an alternative form of the first embodiment aforesaid will now be described. In these figures, similar elements or elements which perform the same function are designated by the same reference numerals preceded by the digit 1 as a unit of hundreds.

Since the arrangements which are common to both alternative forms are fairly numerous, the description will be mainly concerned with the dfferences between the two.

As in the previous form of construction, the deep fryer which is illustrated without its lid comprises a container 101 in which is shown a heating space 106 and a cooking space 107.

Within the heating space 106, a bellhousing 112 is held in position by means of a nut 137 on a central stud 138 which is in turn fixed on the bottom wall 109 of the vessel 101. The bell-housing 112 is fixed on the stud 137 in such a manner that the edge 113 of the skirt 114 of the said bell-housing is located at a certain distance from the bottom wall 109 of the container 101 in order to provide a communication between the interior and the exterior of the bell-housing. Furthermore, the diameter of the bell-housing is such that an annular space 116 of appreciable width remains between the bell-housing and the wall of the container 101.

In this embodiment, shielded electric resistors 108 provided with terminal connectors 111 are placed within the container 101 around the bell-housing 112 within the annular space 116.

A U-shaped reservoir 126 is placed within the interior of the bell-housing in the vicinity of the centre of the fryer. One leg of the U is attached to the bell-housing by means of a flange 1 26a and the end of this leg communicates with the atmosphere of the bell-housing above the normal level 128 of the bath in the cold state by means of an opening 127. The other leg which is provided with a vent 139 is connected to a pipe 131 which traverses the bell-housing 112 through a leak-tight wallbushing and traverses the container 101 through another leak-tight wall-bushing, then extends to the bottom of an open external vessel 129 located at the level of the cooking space 107.

Provision is made between the two leaktight wall penetrations for a flexible tube connection (not illustrated) which can be readily uncoupled in order to permit of disassembly. It will further be noted that the pipe 131 is not illustrated over its entire length for the sake of enhanced clarity.

In the external portion with respect to the container 101, the pipe 131 is provided with a vent 141 for discharge to the atmosphere (Fig. 11) which can be closed-off by means of a check-valve 142 controlled by a moving contact 133 of a relay 134, the wiring of which will hereinafter be more specifically described.

After passing through the bottom wall of the vessel 129, the pipe 131 can be closed-off by means of a check-valve 132 carried by an inverted U-arm 143 slidably mounted for vertical motion within the block in which provision is made for the open external vessel 129. The arm extremity 144 opposite to the extremity which carries the check-valve 132 is chamfered in order to cooperate with the chamfered upper extremity 145 of another arm 146 carried by a push-button 136. The said push-button is flush-mounted in a cover 147 which is protected from the control unit of the fryer. The said cover is fixed on the container 101 by means of screws (not shown) located within recesses 147a (as shown in Fig. 13).

It can be understood that, by depressing the push-button 136, the lateral displacement of the arm 146 results in vertical displacement of the U-arm 143 and in opening of the check-valve 132 as a result of the interaction of the chamfered extremities aforesaid.

There is also placed within the cover 147 a thermostat 135 which is sensitive to the temperature of the bath through the metal of the container 101. The thermostat can be reset under the mechanical action of the arm 146 by means of the push-button 136.

The electric circuit for connecting the elements described in the foregoing is substantially the same as the circuit described in the previous alternative embodiment shown in Fig. 16. The thermostat 135 is connected in series with the coil of the relay 134 and with the heating resistors 108 and is so arranged as to open the circuit when the temperature of the bath attains a predetermined value.

Finally the cover 147 contains a graduated indicating-wheel 148 and the digits of this latter pass in front of a window 149 of the said cover. The said wheel is mounted on a shaft 151 carried by a bracket 152 which is fixed on the container 101. Provision is made on the periphery of the said wheel'for a row of teeth 153 in cooperating relation with a ratchet lever 154 which is intended to be actuated by the lower end of the arm 146 (as shown in Fig. 10).

The set of control means described in the foregoing can be seen more clearly in the perspective view of Fig. 14 although the arrangement of the various elements is slightly different.

The operation of the deep fryer as thus described is slightly different from that of the previous alternative form of construction.

After a suitable quantity of cooking fat has been introduced into the container 101 in order to ensure that the bath reaches the level 128 and the basket 124 filled with food to be fried has been placed on the bellhousing 112, the open external vessel 129 is completely filled with water. The dimensions of the said vessel are such that its capacity corresponds substantially to the quantity of water required for the operation which will now be described. The complete assembly is then in the condition which is shown diagrammatically in Fig. 15.

The push-button 136 is then depressed in order to produce simultaneously the opening of the check-valve 132 by means of the arm 146, the setting of the thermostat 135, the energization of the relay 134 and the onestep rotational displacement of the indicating wheel 148.

As a result of opening of the check-valve 132, the water is permitted to flow from the vessel 129 into the reservoir 126 in which it reaches the level represented by the line 155 whilst the vent 139 ensures pressure equalization within the two legs of the reservoir (Fig. 7).

Setting of the thermostat 135 has the effect of applying voltage to the heating resistors 108 and energizing the relay 134, with the result that the check-valve 142 for discharge to the external atmosphere is closed by means of the contact 133.

Finally, the one-step displacement of the indicating-wheel 148 displays a fresh digit in front of the window 149 in order to indicate that another cooking operation is taking place.

When the push-button 136 is released, the check-valve 132 of the vessel 129 returns to the closed position and the reservoir 126 is isolated from the external atmosphere. As the heating proceeds, the heat transmitted to the bath is in turn transmitted to the reservoir 126. When the temperature of the bath attains approximately 100"C, the water contained in the said reservoir vaporizes and the vapour pressure is exerted on that porition of Zhe free surface of the bath which is located within the bell-housing, thus driving the bath towards the annular space 116 and towards the cooking space 107 through the space provided between the edge 113 of the skirt 114 and the bottom wall 109 of the container.

Cooking then takes place while the temperature of the bath continues to rise as explained above. When this temperature attains a predetermined value such as 1500C corresponding to completion of the cooking process, the thermostat 135 breaks the circuit and the heating stops. At the same time, the relay 134 which is de-energized allows the contact 133 to open the check-valve 142 of the vent 141 for discharge to the external atmosphere, with the result that the vapour is permitted to escape from the bell-housing 112.

The bath then returns downwards into the heating space 106 while being automatically filtered as it passes through the filter 117 and allows draining of the food. After cooling, the appliance is again ready to operate even if cooling is not complete.

Disassembly of the fryer for cleaning purposes is carried out by unscrewing the nut 137 in order to withdraw the bell-housing 112 after first disconnecting the pipe 131.

This alternative embodiment has only relatively minor differences with respect to the previous form of construction. It can be considered that the arrangement of the resistors 108 inside the container 101 and within the bath itself results in lower heat losses.

The arrangement of the vessel 129 and its emptying system ensure more accurate regulation of the quantity of water admitted. The presence of the indicating-wheel 148 which counts the cooking operations constitutes a remarkable trouble-saving device for the user by indicating the moment at which it is necessary to change the bath or to change the cartridge of the deodorizing filter.

Referring now to Figs. 17 to 20, there will now be described a second embodiment of the fryer which differs from the two alternative forms of the first embodiment, mainly in regard to the constructional design of the control means.

It will not be necessary in this case to give a detailed description of the structure of the fryer which can be the same as those described earlier, especially the second alternative form of construction. It has therefore been considered sufficient to illustrate this second form of construction in the diagrammatic or perspective drawings. So far as the common details of construction are concerned, reference can usefully be made to Figs. 7 to 13 and to the description relating to these latter. In Figs. 17 to 20, similar elements or elements which perform similar functions are designated by the same reference numerals preceded by the digit 2 as a unit of hundreds.

As in the case of Figs. 7 to 13, the deep fryer comprises a bell-housing 212 which is fixed within a heating space 206 of a container 201 and makes provision for an annular passage between its bottom edge and the bottom wall 209 of the said container, for example by means of slots 215. Provision is made above the heating space 206 for a cooking space 207 containing a basket 224 in which the food to be cooked is placed.

A filter 217 is mounted within an annular space 216 between the bell-housing 212 and the container 201.

Heating resistors 208 are placed within the container 201 in order to heat a bath of cooking fat.

There is placed within the bell-housing 212 a reservoir 226 which is open to the atmosphere of the bell-housing through an orifice 227 and connected by means of a pipe 231 to an open external vessel 229 by means of a hand-operated check-valve 232.

The said check-valve 232 is connected to an inverted-U arm 243 which can be actuated by an arm 246 connected to a pushbutton 236, this action being produced by means of chamfered end faces in cooperating relation (Fig. 17) in accordance with the detailed description given earlier.

The pipe 231 is further provided with a vent for discharge to the external atmosphere. The said vent can be closed-off by a check-valve 242, the means employed for actuating this latter being described hereinafter.

The fryer is equipped with a thermostatic device comprising a bimetallic strip 259 located in the vicinity of the wall of the container 201 in order to be sensitive to the temperature of this latter. The said device is so arranged as to cooperate under the action of its thermal expansion with a system for triggering the heating circuit.

The trigger system just mentioned comprises a rocker arm 261 pivotally mounted on a pin 262 carried by a yoke 263 which is rigidly fixed to the container 201 (as shown in Fig. 17). A spring 264 produces action on the rocker-arm 261 in order to apply one end portion 265 against one side of a pivotal bell-crank stop 266 which is mounted in the same manner as the rocker-arm 261 and the other side of which is subjected to the action of the bimetallic strip 259. Moreover, the same end portion 265 of the rocker-arm 261 cooperates with a sensitive element 267 of a switch 268 which is connected in series in the heating circuit (as shown in Fig. 20).

It is apparent that the thermal deformation of the bimetallic strip 259 causes pivotal displacement of the stop 266 and withdrawal of the end portion 265 of the rocker-arm 261 from its bearing position. The said rockerarm then pivots under the action of the spring 264 in order to actuate the switch 268 and cut-off the heating current.

The other end of the rocker-arm 261 carries the check-valve 242 mentioned earlier.

The said check-valve is so arranged as to close the vent 241 when the rocker-arm 261 is applied against the stop 266 and in order to close the said vent under the action of the spring 264 when withdrawal from the stop takes place.

The end portion 265 of the rocker-arm 261 is also arranged so as to actuate a sensitive element 265 of a mechanical counting device 271.

Finally, the arm 246 which is coupled to the push-button 236 is so arranged as to produce action on the lever 261 in the direction which tends to compress the spring 264.

The operation of the fryer as described in the foregoing will now be explained.

When the heating space 206 has been filled with suitable cooking fat to a level 228 which is lower than the level of the orifice 227 of the reservoir 226 and when the basket 224 containing the food has been placed within the cooking space 207, the open external vessel 229 is completely filled with water. The appliance is then in the condition shown diagrammatically in Fig. 18.

The push-button 236 is then depressed and, as in the previous example, this causes the check-valve 232 to open and the water to flow from the vessel 229 into the reservoir 226.

Actuation of the push-button 236 also causes pivotal displacement of the rockerarm 261 and compression of the spring 264.

The check-valve 242 carried by the upper end of the said rocker-arm then closes-off the vent 241 for connecting the pipe 231 to the external atmosphere.

The aforesaid pivotal displacement of the rocker-arm 261 has the effect of releasing the lower end 265 of this latter from the bellcrank stop 266, with the result that the said stop is permitted to swing back so that one of its sides is applied against the bimetallic strip 259. The rocker-arm 261 is locked in its new position as a result of the bearing position taken up by this latter on the other side of the stop 266 (as shown in Fig. 19).

During its displacement the lower end 265 of the rocker-arm 261 is applied against the sensitive element 267 of the switch 268 which has the effect of closing the heating circuit and at the same time against the sensitive element 269 of the mechanical counting device 271, the indication of which increases by one unit.

As in the examples described in the foregoing, heating results in vaporization of the water and the steam drives the bath towards the cooking space 207 in order to put this latter in contact with the food.

When the bath attains a predetermined temperature such as 150"C, for example, the bimetallic strip 259 undergoes a sufficient degree of deformation to initiate pivotal displacement of the stop 266 which thus releases the rocker-arm 261 (Fig. 18). This clearly results in interruption of the heating and opening of the vent 241 for discharge to the external atmosphere, thus permitting downward return of the bath into the heating space after automatic filtration of the bath.

The advantage of this embodiment lies in the fact that electrical components are dispensed with as far as possible. This is always desirable in the case of a domestic appliance which is intended to be washed with water.

All the embodiments hereinabove described can be improved by adding a programming device for,starting the cooking automatically at a predetermined time. The user does therefore not need to be present at that time in order to depress the push-button 36, 136, 236. This device is knownperse and is designated only in diagrammatic form by the references 172, 272 but will not be described in detail.

Referring to Figs. 21 to 23, there will now be described certain alternative forms of construction which can be common to all the examples described earlier or to a certain number of these latter.

Thus in the event that the heating resistors 308 (Fig. 21) are mounted inside the container 301, the bell-housing 312 can be secured by means of retaining latches 373 rotatably mounted in bearings 374 which are rigidly fixed to the bell-housing and attached to the resistors. It is only necessary to rotate the retaining latch within the bearings in order to release the resistors. Provision is therefore no longer made within the heating space for the stud 138 shown in Fig. 7.

Provision can also be made for a retaining latch 473 which is of the same type (Fig. 22) but which is engaged on a boss 475 formed on the internal wall of the container. This alternative design can be adopted even if the heating resistors 408 are located outside the container 401.

One of the important advantages of the fryer in accordance with the invention lies in the fact that cooking takes place whilst heating of the bath still continues. In consequence, the final temperature of the bath is lower than the temperature attained in conventional fryers in which the cooking process takes place in a shorter time with greater turbulence in a bath which is heated to its maximum temperature from the outset. This advantage results in longer service life of the deodorizing filter which is subjected to a relatively small flow of ill-smelling vapour and in better preservation of the bath against any form of impairment.

A further consequence of the foregoing is that the lid of the container is subjected to lower pressure and this can be turned to profitable account by designing a different type of lid.

In the embodiment described earlier with reference in particular to Fig. 2, the lid 2 is pivotally mounted on the container 1 on the left-hand side of the figure by known means (not shown in the figure). On the opposite side, the lid 2 is maintained in the closed position by means of a catch 76 which is resiliently fixed on the container 101 by means of a strip 77 and is applied against a flange 78 of the lid 2.

This form of construction provides a locking action and the lid can accordingly remain closed even if a certain vapour pressure is exerted above the turbulent bath.

Now this pressure can be reduced in accordance with the invention as has just been explained, thus making it possible to contemplate a lid design which will now be described with reference to Fig. 23.

In accordance with this design, a container 501 provided with handling lugs 581a, 581b is covered by a lid 502 provided with a hinged component 582 formed of material which is endowed with a certain degree of resilience such as plastic, for example.

The component 582 has two webs 583 in which is formed a keyhole slot 584 forming a resilient clip in which is inserted a wire 585 constituting a pivot-pin and bent in such a manner as to permit of its insertion in the fixing member of the adjacent lug 581a. As can be understood, the lid 502 is thus locked about its pivot-pin but can be readily removed by utilizing the resilience of the component 582.

The lid 502 cooperates with the container 501 by means of a seal 586 which forms a skirt and ensures leak-tightness solely under the action produced by the weight of the lid.

This result can be achieved only by virtue of the low vapour pressure which prevails above the bath in a fryer in accordance with the invention.

On the side opposite to the hinge, the lid 502 is provided with an operating handle 587 formed preferably of heat-insulating material and comprising a bent-back gripping portion 588 which is directed towards the axis of the frying appliance. The result thereby achieved is that the user's hand is continuously protected by the lid against expansion of steam and radiation of hot food when the lid of the hot fryer is opened.

The advantages offered by the invention lie mainly in a cooking operation which is fully automatic from the time of start-up.

This automatic operation can be even made to include starting of the appliance by adding a programming device.

The automation thus achieved is conducive not only to convenience of use but also to a saving of power, to better quality of cooking and to longer service life of the consumable elements, namely the bath and the cartridge of the deodorizing filter.

Further secondary advantages have been mentioned in the course of the foregoing description.

As can readily be understood, the inven tion is not limited to the examples hereinabove described. Thus is would not constitute any departure from the scope of the invention to contemplate many alternative forms of construction of the type indicated in the foregoing as well as more important alternatives relating for example to the constructional design of the control mechanisms. It would also be possible to arrange the heating and cooking spaces in a different manner with respect to each other, for example in two separate units connected to each other by means of piping systems. Provision could also be made for permanent attachment of the filter to the bell-housing in order to reduce the number of separable components.

WHAT WE CLAIM IS: 1. A deep fryer especially for domestic use comprising a heating space for a bath of cooking fat, a cooking space for receiving food in communication with said heating space, and pumping means for displacing the bath from said heating space to said cooking space to put it in contact with the food, characterized in that the pumping means comprise means for applying to a part of the free surface of the bath in the heating space the vapour pressure of a liquid which is immiscible with the bath and which has a predetermined boiling point, said pressure being sufficient to drive the bath from said heating space to said cooking space.

2. A fryer in accordance with claim 1, characterized in that the heating space and the cooking space are two communicating zones of the same container.

3. A fryer in accordance with claim 2, characterized in that the pumping means comprise a bell-housing so arranged that the edge of the skirt of the said housing is maintained in the vicinity of the bottom wall of the container and that the end wall of the bellhousing is located above the normal level of the bath outside the cooking periods, an annular space being formed between the lateral wall of the container and the skirt of the bell-housing, the means aforesaid being further constituted by a reservoir which is in communication with the atmosphere of the bell-housing and is thermally coupled with the heating means of the heating space, the said reservoir being intended to receive a predetermined quantity of the aforesaid immiscible liquid whose boiling point at atmospheric pressure corresponds substantially to the temperature at the beginning of the cooking process.

4. A fryer in accordance with claim 3, characterized in that it comprises a filter placed in the passage between the heating space and the cooking space.

5. A fryer in accordance with any one of claims 1 to 4. characterized in that the cooking space is located above the heating space and provided with a removable basket for receiving food.

6. A fryer in accordance with any one of claims 3 to 5, characterized in that it comprises an open external vessel connected by means of a pipe to the reservoir aforesaid.

7. A fryer in accordance with claim 6, characterized in that the pipe aforesaid has a vent for discharge to the external atmosphere which can be selectively closed-off by means of a check-valve provided with mechanical actuating means.

8. A fryer in accordance with claim 7 in which the heating space is fitted with heating resistors, characterized in that it comprises a thermostat which can be manually reset by means of a push-button and which is responsive to the temperature of the bath in order to interrupt the heating automatically when the said temperature attains a predetermined value.

9. A fryer in accordance with claim 8, characterized in that the means for actuating the check-valve comprise an electromagnetic relay, the coil of the said relay being connected to the thermostat in order to initiate opening of the said check-valve at the same time as interruption of the heating.

10. A fryer in accordance with claim 9, characterized in that the open external vessel is located at a level such that when the said vessel is completely filled with water, the quantity of water introduced in the reservoir located within the bell-housing corresponds substantially to the quantity of water required for the operation.

11. A fryer in accordance with claim 9, characterized in that the open external vessel is located at the level of the cooking space and that the said vessel is connected to the pipe by means of a check-valve provided with mechanical actuating means connected to the control push-button of the thermostat.

12. A fryer in accordance with claim 8, characterized in that the thermostat comprises a bimetallic strip located in the vicinity of the container wall and so arranged as to cooperate with a system for triggering the heating circuit under the action of thermal deformation of the said bimetallic strip.

13. A fryer in accordance with claim 12, characterized in that the triggering system comprises a rocker-arm in cooperating relation with a sensitive element of a switch placed in the heating circuit, one end of the said rocker-arm being applied under the action of elastic means against one side of a pivotal bell-crank stop whilst the other side of the said stop cooperates with the bimetallic strip.

14. A fryer in accordance with claim 13, characterized in that the other end of the rocker-arm carries the check-valve which serves to close-off the orifice for connecting the pipe to the external atmosphere.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. tion is not limited to the examples hereinabove described. Thus is would not constitute any departure from the scope of the invention to contemplate many alternative forms of construction of the type indicated in the foregoing as well as more important alternatives relating for example to the constructional design of the control mechanisms. It would also be possible to arrange the heating and cooking spaces in a different manner with respect to each other, for example in two separate units connected to each other by means of piping systems. Provision could also be made for permanent attachment of the filter to the bell-housing in order to reduce the number of separable components. WHAT WE CLAIM IS:

1. A deep fryer especially for domestic use comprising a heating space for a bath of cooking fat, a cooking space for receiving food in communication with said heating space, and pumping means for displacing the bath from said heating space to said cooking space to put it in contact with the food, characterized in that the pumping means comprise means for applying to a part of the free surface of the bath in the heating space the vapour pressure of a liquid which is immiscible with the bath and which has a predetermined boiling point, said pressure being sufficient to drive the bath from said heating space to said cooking space.

15. A fryer in accordance with claim 14

in which the open external vessel is located at the level of the cooking space and connected to the pipe by means of a check-valve provided with actuating means, characterized in that the said actuating means are connected mechanically to a push-button so arranged as to be also in cooperating relation with the rocker-arm in order to reset the thermostat.

16. A fryer in accordance with claim 11 or claim 15, characterized in that it comprises mechanical means for counting the successive cooking operations, the said means being connected to the control push-button aforesaid.

17. A fryer in accordance with any one of claims 4 to 16, characterized in that the filter rests partly on the bottom wall of the bellhousing and is provided with separable means for attachment to the lateral walls of the container.

18. A fryer in accordance with claim 17, characterized in that the means for attaching the filter are located in such a manner that the said means maintain the edge of the skirt of the bell-housing applied against the bottom wall of the container, the said edge being provided with slots in order to establish a communication between the interior of the bell-housing and the exterior.

19. A fryer in accordance with claim 18, characterized in that the means for attaching the filter comprise at least two resilient strips attached to the filter and extending along the lateral walls of the container, the said strips being provided with studs for cooperating with cavities formed in the said walls.

20. A fryer in accordance with any one of claims 17 to 19, characterized in that the filter is annular and that the end wall of the bell-housing has a deformed portion in order to ensure centring of the said bell-housing with respect to the said filter.

21. A fryer in accordance with any one of claims 4 to 20, characterized in that the filter is permanently attached to the bell-housing.

22. A fryer in accordance with any one of claims 3 to 17, characterized in that the means for maintaining the bell-housing in position comprise a threaded stud located substantially in the axis of the container and fitted with a nut which is applied against the said bell-housing.

23. A fryer in accordance with any one of claims 3 to 17, characterized in that the means for maintaining the bell-housing in position comprise movable retaining latches pivotally mounted on the bell-housing and so arranged as to be applied against a member which is rigidly fixed to the container.

24. A fryer in accordance with claim 23, characterized in that the retaining latches are applied against bosses formed in the lateral wall of the container.

25. A fryer in accordance with claim 23, characterized in that the retaining latches are applied against at least one of the heating resistors located within the container.

26. A fryer in accordance with any one of claims 1 to 25 and comprising a lid provided at the centre thereof with a deodorizing filter, characterized in that the lid is pivotally mounted on its hinge-pin by means of two resilient clips which permit removal of the said lid.

27. A fryer in accordance with claim 26 in which the lid comprises gripping means for handling the said lid, characterized in that the said means are so arranged as to be accessible by placing a hand over the said lid.

28. A fryer in accordance with any one of claims 8 to 27, characterized in that it comprises actuating and time-control means for automatically actuating at the end of a predetermined time interval the different control means which are connected to the pushbutton.

29. A deep fryer, especially for domestic use, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.