GB2030687A - Method and apparatus for heating a liquid - Google Patents

Abstract

Hot water is delivered to a tea or coffee filter 14 through a riser 17 from a bulk supply 16. The bulk supply is heated by a first heating element 22 to a temperature below the boiling point. When infusion is required, a second heating element 23 beneath the riser is energised to boil water in the vicinity of the second heating element. The bulk supply is replenished through valve 21 after the second heating element has been de- energised. <IMAGE>

Description

SPECIFICATION Method and apparatus for heating a liquid DESCRIPTION OF INVENTION This invention relates to a method and apparatus for heating a liquid. The invention has been developed primarily for use in the preparation of hot beverages by infusing solid matter in water.

One common method of preparing coffee is to place a bulk supply of cold water in a chamber from which the water can flow past an electrical heating element to a riser from which hot water can be discharged into a filter containing coffee grounds. When the heating element is energised, water in the vicinity of the heating element boils and is carried by the resulting vapour up the riser.

Unless energy is supplied to the heating element at a high rate, the rate of flow of water through the riser is small. In consequence of this, the coffee grounds may not be flooded at all or flooded quickly and there will be a considerable delay between energisation of the heating element and eompletion of the infusion process.

According to a first aspect of the invention, there is provided a method of supplying hot liquid wherein a bulk supply of the liquid is heated to a temperature below its boiling point and liquid from the hot bulk supply is further heated at a position in or beneath a riser to cause said liquid from the bulk supply to boil and flow up the riser.

The liquid may be directed from the riser into a filter containing coffee grounds or tea leaves.

Since the bulk supply of liquid is heated prior to flow of any of the liquid up the riser, the rate of flow in the riser can be high without supplying energy at a high rate. The delay between commencement of flow of liquid up the riser and completion of the infusion process can be short.

Preferably, the rate of flow of liquid up the riser is reduced after a maximum flow rate has been achieved. In a case where the liquid is directed from the riser into a filter containing coffee grounds or tea leaves, the maximum flow rate may be selected to flood the coffee grounds or tea leaves quickly without risk of the liquid overflowing from the filter, which might occur if the flow continued at the maximum rate.

The rate of flow of liquid up the riser may depend on the pressure head exerted by said bulk supply at a lower end of the riser, the head being reduced as the liquid flows from the bulk supply up the riser.

The pressure head when the flow of liquid up the riser commences may correspond to a level of a free surface of the bulk supply of liquid which is below an upper part of the riser.

According to a second aspect of the invention, there is provided a method of supplying hot liquid wherein the liquid flows from a bulk supply to a discharge point, the liquid is heated as it flows to the discharge point, the rate at which the liquid flows to the discharge point is dependent on the pressure head caused by the bulk supply of liquid and the pressure head falls as the liquid flows from the bulk supply to the discharge point, thereby causing the rate of flow to fall.

The liquid may be heated whilst in the bulk supply before it commences to flow to the discharge point. The flow of liquid to the discharge point is preferably terminated before the bulk supply is replenished.

According to a further aspect of the invention, there is provided apparatus comprising a chamber for containing a bulk supply of liquid, a riser connected at a lower end of the riser with the interior of the chamber at a position below the top of the chamber, a heating element in or beneath the riser and a further heating element arranged for heating liquid in the chamber.

The apparatus may further include a baffle which extends around a heating element disposed.

beneath the riser, the baffle being downwardly open and communicating upwardly with the riser.

There may be provided in the chamber an overflow opening. The riser preferably extends above the overflow opening.

A method and apparatus embodying the invention will now be described, by way of example, with reference to the accompanying drawing which shows diagrammatically a beverage maker.

The beverage maker shown in the accompanying drawing is intended for fitting in an aircraft to be used for the preparation of beverages by infusing tea leaves, coffee grounds or the like in hot water. The beverage maker comprises a main body 10 which, in use, is releasably secured to the structure of the aircraft In the body there is mounted a platform 11 for supporting a jug 1 2.

The platform is arranged for iimited rocking movement relative to the body 10 aginst the action of a spring (not shown). Means may be provided for adjusting the degree of compression of the spring in order to vary the minimum load on the platform which is necessary to move the platform from its normal, raised position. When the empty jug is present on the platform, the platform is maintained in its normal position by the spring. When the jug contains a predetermined quantity of beverage, the platform rocks from its normal position and operates an electric switch (not shown) called herein the platform switch, which provides a signal indicating that the required amount of beverage has been prepared.

The apparatus further comprises a retainer for releasably retaining the jug 12 on the platform 11.

The retainer is in the form of a loop 1 3 which, when in its operative position, extends around an upper marginal portion of the jug. The loop is hingedly connected with the body 10 and can be pivoted upwardly from the jug to enable the latter to be withdrawn from the platform.

Above the retaining loop 13, there is mounted on the body 10 a basket 14 for containing coffee grounds or tea leaves and filtering such solids from the liquid in which they are infused. The basket has laterally outwardly projecting flanges which run on respective rails 1 5 provided on the body 10 to enable the basket to be supported in a position vertically above the jug 1 2 and to be withdrawn forwardly from the body.

Within the body 10 and situated rearwardly of the jug 12 and basket 14, there is a chamber 16 for containing a bulk supply of water. A riser 1 7 extends upwardly through the chamber from a position near to the bottom. thereof. The riser extends through an upper wall of the chamber and then forwardly to a position vertically above the centre of the basket, 14 where the riser terminates in a downwardly directed discharge portion 1 8.

The chamber 1 6 is provided with an overflow opening 19 disposed art a level below the upper wall of the chamber. There also communicates with the interior of the chamber a water inlet 20 which is controlled by a solenoid-operated valve 21. When the apparatus is installed in an aircraft, the inlet 20 is connected with a pressurised cold water supply. There is disposed in the chamber 16, at a level below that of the overflow 1 9 one or more electrical heating elements 22. A further electrical heating element 23 is positioned in the chamber directly beneath a lower end of the riser 17. Around the heating element 23, there is provided a baffle 24 which is downwardly open and communicates upwardly with the riser.

It will be noted that there are no valves or other obstructions in the riser 1 7. The discharge portion 1 8 thereof is permanently open and is permanently in communication through the chamber 16 with the overflow opening 1 9.

Accordingly, there cannot be established in the chamber 16 or in the riser 1 7 a pressure of air or vapour significantly in excess of the aircraft cabin pressure or other ambient pressure.

The inlet valve 21 is controlled, in part, by a water-level detecting means in the chamber 16, for example a float-operated switch. The valve 21 can be opened only when the level of the free surface of water in the chamber 1 6 is below a predetermined level, which predetermined level is below the level of the overflow opening 19 but above the heating elements 22 and 23. A further water-level detecting means (not shown) is so associated with the heating element 22 as to prevent energisation of that heating element unless the heating element is covered by water.

Alternatively, a single water-level sensing means may be provided, the arrangement being such that unless the water is up to a predetermined level the heating element 22 cannot be energised and that the inlet valve 20 cannot be opened if the water is up to that predetermined level.

Energisation of the heating element 23 is subject, in part, to control by a jug switch 25 and a retainer switch 26. The jug switch 25 is operated when the jug is placed in its proper position on the platform 11 and the retainer switch is operated when the retainer is placed in its proper position about the upper part of the jug. Only when both of these switches have been operated can the heating element 23 be energised.

The apparatus is used in the following manner to heat water and prepare a jug of coffee. When the supply of electric power to the apparatus is switched on, the inlet valve 21 is opened, unless water is already present in the chamber 1 6 up to the required level. The heating element 22 is energised. The basket 1 4 is withdrawn from the body 10, is charged with coffee grounds and is replaced in the position shown in the drawing.

When the temperature of the water in the chamber 1 6 has reached a value just below the boiling point of the water under the ambient pressure, the heating element 22 is de-energised by a thermostat (not shown). The thermostat causes the heating element to cycle on and off in order to maintain the temperature of the water at the predetermined value. When the temperature first reaches this value, an indicator lamp (not shown) is illuminated to indicate that the water is ready for use. A switch is then operated to energise the heating element 23. In order to minimise the maximum power requirements of the apparatus, the arrangement may be such that the heating element 22 cannot be energised whilst the heating element 23 is energised.

The heating element 23 supplies heat to that small part of the mass of water contained in the chamber 1 6 which lies within the baffle 24. This water is rapidly heated to the boiling point and commences to boil. The vapour generated by boiling moves up the riser 1 7 and carries up the riser water which is at the boiling point Further water moves into the baffle 24 through the open lower end thereof and is heated by the element 23. The water which is carried up the riser is discharged through the discharge portion 18 into the basket 14.

The rate of flow up the riser 1 7 depends upon the rate of heat input by the element 23 and also upon the pressure head exerted by the water in the chamber 16 at the lower end of the riser 17.

Initially, this pressure head is relatively large and the rate of flow of water up the riser increases rapidly to a maximum value which is sufficient to flood the coffee grounds in the basket 1 4. As the flow of water up the riser continues the head in the chamber 1.6 falls and the rate of flow is reduced graduaily. When the required amount of water has entered the jug 12 the platform 11 rocks to operate the platform switch which deenergises the heating element 23. The inlet valve 21 is then opened once more to replenish the supply of water in the chamber and the heating element 22 is energised once more to heat that supply of water. Whilst the heating element 23 is energised the inlet valve 20 is isolated from the electrical power supply and cannot be opened.

The volume of water in the chamber 1 6 prior to energisation of the heating element 23 is such that this heating element is covered by water upon operation of the platform switch, even when the spring loading of the platform is adjusted to provide the maximum amount of coffee.

Claims (11)

1. A method of supplying hot liquid wherein a bulk supply of the liquid is heated to a temperature below its boiling point and liquid from the hot bulk supply is further heated at a position in or beneath a riser to cause said liquid from the bulk supply to boil and to flow up the riser.

2. A method according to claim 1 wherein, after a maximum rate of flow of liquid up the riser has been achieved, the rate of flow up the riser is reduced whilst flow continues.

3. A method according to claim 2 wherein the reduction in the rate of flow of liquid up the riser corresponds to a reduction in the pressure head exerted by said bulk supply at a lower end of the riser.

4. A method according to claim 3 wherein, at the commencement of flow of liquid up the riser, the pressure head exerted by said bulk supply at the lower end of the riser corresponds to a level of a free surface of the bulk supply of liquid which is below an upper part of the riser.

5. A method of supplying hot liquid wherein the liquid flows from a bulk supply to a discharge point, the liquid is heated as it flows to the discharge point, the rate at which the liquid flows to the discharge point is dependent on the pressure head caused by the bulk supply of liquid and the pressure head decreases as the liquid flows from the bulk supply to the discharge point, thereby causing the rate of flow to decrease.

6. A method according to claim 5 wherein the liquid is heated whilst in the bulk supply before it commences to flow to the discharge point.

7. A method according to claim 5 wherein the flow of liquid to the discharge point is terminated before the bulk supply is replenished.

8. Apparatus comprising a chamber for containing a bulk supply of liquid, a riser connected with the interior of the chamber at a lower end of the riser which is disposed below the top of the chamber, a first heating element in or beneath the riser and a further heating element arranged for heating liquid in the chamber.

9. Apparatus according to claim 8 wherein the first heating element is disposed beneath the riser, the apparatus further includes a baffle which extends around the first heating element, the baffle is downwardly open and the baffle communicates upwardly with the riser.

10. Apparatus according to claim 8 or claim 9 wherein an overflow opening is provided in the chamber.

11. Apparatus according to claim 9 wherein the riser extends above the overflow opening.

1 2. A method of supplying hot liquid substantially as herein described and illustrated in the accompanying drawing.

1 3. A method according to any one of claims 1 to 7 and claim 12 wherein the liquid is directed from the riser onto a mass of coffee grounds or tea leaves to prepare an infusion of coffee or tea.

1 4. Apparatus substantially as herein described with reference to and as illustrated in the accompanying drawing.

1 5. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.