GB2221610A - Apparatus for brewing coffee - Google Patents

Abstract

A coffee brewing apparatus 10 comprises a water reservoir 11 with heating means and a coffee urn 12, the reservoir 11 having an inlet port 13 and an outlet port 22. The level of water in the reservoir 11 is primarily controlled by a level detector 19 and a water inlet valve 15. To brew coffee, the detector 19 is deactuated and water flows into the reservoir 11 which results in an overflow of water through the outlet 22. A second water level detector 20 closes the valve 15 when the water level reaches it. The water level falls below the second detector 20 and the valve 15 is opened again. Water from the outlet 22 flows over coffee in a filter located in the mouth of the urn 12. This cycle continues until a pre-set time has elapsed or the liquid level in the urn 12 reaches a third water level detector means 21. <IMAGE>

Description

APPARATUS FOR BREWING COFFEE This invention relates to an apparatus for brewing coffee. In particular, it relates to an apparatus for brewing coffee on a commercial rather than a domestic scale. More particularly, it relates to an apparatus for brewing coffee which employs a so-called filter technique.

Coffee brewing machines which employ the filter technique are well known. Generally, they comprise a reservoir for cold or hot water; and ducting for conveying the water to an outlet head located above a quantity of coffee placed in a suitable filter paper mounted in a filter paper holder located above a brewed coffee storage vessel or urn.

In commercial. machines, preheated hot water is used (rather that in-line heating of water as in domestic machines). The hot water is conveyed to the outlet head by means of a pump.

A difficulty frequently encountered with the known commercial machines is that the pump mechanism is prone to failure or leakage.

It is an object of the present invention to overcome these problems and to provide a coffee brewing machine with a number of features providing improvements over the known coffee brewing machines.

The invention, therefore, provides an apparatus for brewing coffee which apparatus comprises a reservoir for water; means for heating the water to a temperature suitable for brewing coffee; an inlet port for cold water located at or near the base of the reservoir; an outlet port for heated water located at or near the top of the reservoir; a pipe in liquid communication with the outlet port for enabling water which flows through the outlet port to flow over coffee retained in a suitable filter thereby providing brewed coffee; means for collecting the brewed coffee; and means for controlling the input of water to the reservoir which in turn controls the flow of water through the outlet port.

Preferably, the means for controlling the flow of input water comprises a valve means operatively associated with a first water level detector means located on a notional line corresponding to a level of water just below the outlet port so that when the level reaches the first detector means, a first output signal from the first detector means closes the valve means.

Preferably, the valve means is operatively associated with a second water level detector means located on a notional line corresponding to a level of water at or above the outlet port; and means for deactuating the first detector means is provided so that when the first detector means is deactuated and the water level reaches the second detector means, a second output signal from the second detector means closes the valve means.

Preferably, wherein the coffee collecting means comprises an urn housed in the reservoir.

Preferably, wherein a third liquid level detector means operatively associated with the valve means is located on a notional line corresponding to the desired maximum level of liquid in the urn so that, in use, when the liquid level reaches the third detector means, a third output signal from the third detector means closes the valve means.

Preferably, a liquid distributor means is provided comprising a plate member having a chamber located on one face thereof; the chamber having a side opening therein for enabling the pipe to be in liquid communication therewith; and a plurality of openings in the wall of the chamber so that, in use, with the plurality of openings located above the filter, water, which enters the chamber from the pipe, is distributed evenly over the coffee.

Preferably, the number and/or size of the plurality of openings is such as to allow, in use, water to accumulate in the chamber thereby providing a constant flow of water through the plurality of openings.

Preferably, the openings are distributed so as to provide, in use, a flow of water over substantially the entire exposed surface area of coffee in the filter.

The invention will be understood in greater detail from the following description of preferred embodiments thereof given by way of example only and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a coffee brewing apparatus according to the invention; Figure 2 is a perspective internal view of the apparatus of Figure 1 of the drawings; Figure 3 is a side elevation of the apparatus of Figure 1 of the drawings; Figure 4 is a rear elevation of the apparatus of Figure 1 of the drawings with the back panel removed; Figure 5 is a plan view of the apparatus of Figure 1 of the drawings with the cover removed; Figure 6 is a plan view of the apparatus of Figure 1 of the drawings with the cover removed but with the coffee filter and holder in position; Figure 7 is a cut away view of the upper part of the apparatus of Figure 1 of the drawings; and Figure 8 is an underneath perspective view of the cover for use with the apparatus of Figure 1 of the drawings; and Figure 9 is an electrical/electronic diagram of components used with the apparatus of Figure 1 of the drawings.

Referring now to the drawings, there is shown a coffee brewing apparatus 10 according to the invention which comprises a water reservoir 11 and a coffee urn 12. The reservoir 11 is of rectangular cross-section with the urn 12 located centrally therein. The reservoir 11 has a water inlet port 13 connected to a pipe 14 which may be directly connected to a water source from a mains water supply. The supply of water to the reservoir 11 is controlled by a solenoid operated valve 15.

Located near the base of the reservoir 11 and preferably below the urn 12 for ease of installation and removal is an immersion heating element 46.

The reservoir 11 has a tap 16 for dispensing hot water therefrom; the urn 12 has a tap 17 for dispensing brewed coffee therefrom.

The reservoir has three water level detector probes viz a first probe 18; a second probe 19; and a third probe 20. The urn 12 has a liquid level detector probe 21.

The reservoir 10 has an outlet 22 in liquid communication with the urn 12. The outlet 22 is located near the top of the reservoir 11. The relationship between the location of the outlet 22 and the second and third probes 19, 20 is important. The second probe 19 should be located so that when the water in the reservoir 11 reaches it, the level of water is below the outlet 22. The third probe 20 should be located so that when the water level reaches it, the water can flow through the outlet 22.

The second and third probes 19, 20 are connected to appropriate electronic and electrical circuitry so as to control the valve 15. Further detail in relation to these probes is given later in the Specification.

The first probe 18 is located so that when the water level reaches it, the level is above the heating element 46 located in the reservoir 11.

The apparatus 10 further comprises a PCB 23 having a high level relay 25; a heating relay 26; and a low water relay 27 thereon. In addition, the apparatus 10 has a full brew relay 28; a half-brew timer 29 and a brewing contactor or relay 24. The apparatus 10 also comprises an on/off switch 31; a full brew switch 32; a half-brew switch 33; a ready-to-brew light 34; a power-on light 44; a heater "on" indicator light 45; and a transformer 47. The brewing relay 24, the full brew relay 28 and the half-brew timer 29 are mounted in a housing 30. All of the electrical components are connected by cables 35 and powered from mains voltage electricity via cable 36. It will be appreciated that, for example, the full brew relay 28 and/or the brewing relay 24 could also be mounted on the PCB 23.

The reservoir 10, coffee urn 11 and all other components thereof are enclosed in a housing 37 including a removable back panel 38; an access port closed by a plate 39 in a side panel 40; and a front panel 41 thereof. The removal only of the plate 39 enables access to the heating element for replacement if required.

The front panel 41 has mounted thereon the on/off switch 31; the full brew switch 32; the half-brew switch 33 the ready-to-brew light 34;'and the heater "on" light 45. The power on light 44 is incorporated in the on/off switch 31. The front panel 41 also has openings for the pipes 42 for the taps 16, 17 and an opening 43 for enabling the level of liquid in the urn 12 to be visually inspected in a tube (not shown) in liquid communication with the urn 12.

In use, the apparatus 10 operates as follows. The on/off switch 31 is switched on to electrically power the apparatus 10. The second probe 19 detects low or no water thereby opening the valve 15 via the lower water relay 27. Water enters the reservoir 11 but until such time as the water level is at or above the first probe 18, the heating element 46 will remain inactive.

The first probe 18 is located so that when the water level reaches it, power is supplied to the heating element 46 via the heating relay 26. At the same time, the valve 15 is closed until the water 0 reaches a pre-set temperature of about 96 C detected by a temperature probe (now shown). The heating element 46 is then deactuated and the valve 15 opens to allow more water into the resevoir 11. As soon as the temperature of the water falls below the pre-set level, the heating element 46 is actuated and the valve 15 is closed. This cycle continues until the water reaches the second probe 19 whereupon the valve 15 is closed via the high level relay 25. This is to ensure that when the water level reaches the second probe 19, it is at a working temperature of about 0 96 C.

The temperature..probe, which should be located near but not beside the water inlet pipe 14, continues to monitor the water temperature.

If the temperature falls below a pre-set limit (approximately 93 0C) the heating element 46 is again actuated.

When the water temperature is at approximately 96 0C, the ready-to-brew light 34 switches on to indicate that the apparatus 10 may be used for brewing coffee.

If the user requires a full brew of coffee, the appropriate amount of coffee powder is placed in a coffee filter paper 50 housed in the filter holder 51 having a handle 52. The holder 51 together with the filter paper 50 and the coffee powder are placed through the mouth of the urn 12. The relationship between the handle 52 and the holder 51 is such as to enable the holder 51 to rest below the outlet 22.

When the full brew switch 32 is placed on, the full brew relay 28 is actuated, the second probe 19 is deactuated and the third probe 20 actuated.

Accordingly, the valve 15 opens to allow water to enter the reservoir 11 thereby causing the water level to rise and continue to rise until the level reaches the third probe 20.

As the water level rises, the water overflows from the reservoir 11 to the urn 12 via the outlet 22.

0 The overflowing water, which is at about 95 C, flows over the coffee powder in the filter paper 50 and subsequently collects in the urn 12 as brewed coffee.

When the water level reaches the probe 20, the valve 15 is closed via the high water relay 25 and the water level falls below the third probe 20. The flow of water through the outlet 22 diminishes but does not stop completely because the relationship between the location of the probe 20 and the outlet 22 is such that the water level falls below the probe 20 before falling completely below the outlet 22.

When the water level falls below the third probe 20, the valve 15 opens and the water level rises again until the level reaches the third probe 20 whereupon the valve 15 closes again. This cycle continues until the level of brewed coffee in the urn 12 reaches the liquid detector probe 21 whereupon the valve 15 closes. The valve 15 stays closed even when the water level in the reservoir 11 falls below the third probe 20 because the second probe.l9 is again actuated to maintain the level of water thereat and no higher.

It will be appreciated that following closure of the valve 15, water will continue to flow and finally trickle from the outlet 22 until such time as the water level falls below the outlet 22. Under certain circumstances, this can be undesirable. To overcome this problem, an outlet valve (not shown) may be installed on the outlet 22 to operate when the level of brewed coffee in the urn 12 reaches the liquid detector probe 21. The outlet valve would remain closed until the switch 32 or the switch 33 is placed on.

The period of on/off switching of the valve 15 is about 10-20 seconds with a preferred cycle time of about 12 seconds. It will be appreciated that as the valve 15 opens, cold water enters the reservoir 11.

The temperature of the water in the vicinity of the temperature probe will fall thereby actuating the heating element 46. However, if the capacity of the reservoir 11 is about double the capacity of the urn 12 and having regard to the rate at which hot water flows through the outlet 22, the temperature of the water at the outlet 22 will, at all times, be about 96 0C. The capacity of the urn 12 is approximately 7 litres and the rate of flow of water from the outlet 22 is about 0.85 litres/minute.

Hot water or brewed coffee may be dispensed from the apparatus 10 via the taps 16, 17, respectively.

The level of coffee in the urn 12 may be monitored by means of the tube viewed through the opening 43.

If it is desired to brew a volume of coffee equal to about half the volume of the urn 12 (a so-called half-brew), the appropriate amount of coffee powder is placed in the filter paper 50 which is then inserted into the urn 12 as previously described. The operator then places the half-brew switch 33 on which, if the water is at the correct temperature monitored by the temperature probe, deactuates the second probe 19 and actuates the third probe 20 whereupon the valve 15 opens. The half-brew timer 29 is also actuated. The opening of the valve 15 allows the input of cold water with the resulting output of hot water from the outlet 22 as previously described. The cycle of opening and closing of the valve 15 takes place as previously described. After the period pre-set into the half-brew timer 29 times out, the second probe 19 is again actuated thereby preventing the further flow of water input via the valve 15 which results in an absence of water through the outlet 22.

The period programmed into the half-brew timer 29 is such as to allow a sufficient period of time (about four minutes) to elapse which enables a volume of water equal to about one-half the volume of the urn 12 to flow from the reservoir 11 into the urn 12. It would be prudent for the operator not to use the tap 16 during a half-brew period because the water volume passing from the reservoir 11 to the urn 12 may not equal the required volume of water due to a fall in water level below the outlet 22. If desired, a valve may be installed on the pipe 42 which would close when the half-brew period is operational to prevent removal of water from the reservoir 11 via the tap 16.

It will be appreciated that a half-brew period may be selected regardless of the level of brewed coffee in the urn 12. However, even if the half-brew timer 29 has not timed out and the brewed coffee level in the urn 12 reaches the liquid detector probe 21, the latter will override the half-brew timer 28 and so actuate the second probe 19 thereby preventing the further input of water via the valve 15 and the flow of water from the reservoir 11 to the urn 12.

To facilitate the smooth transfer of water from the outlet 22 to the coffee powder in the filter paper 50, a liquid distributor means 60 is provided. The distributor means 60 comprises a plate 61 of circular cross-section having a cut-out portion 62 for enabling the handle 52 to pass therethrough. The plate 61 supports a lifting handle 63 on the upper surface thereof and a chamber 64 on the lower surface thereof.

The chamber 64 comprises two side walls 65, 66; two end walls 67, 68; and a base 69. The end wall 67 has a hole 70 and the base 69 has a plurality of openings 71 therein. Except for the hole 70 and the openings 71, the chamber 64 is sealed. The distributor means 60 also functions as a cover for the urn 12.

In use, following the placement of the filter holder 51 together with the filter paper 50 and coffee powder in position as previously described, the means 60.is placed over the mouth of the urn 12 so as to close it. By placing the distributor means 60 in position, the hole 70 is placed around the opening 22 so that water which flows through the opening 22 first flows into the chamber 64 and then through the openings 71. The openings 71 are relatively small in diameter being distributed in the base 69 as desired.

The diameter of the openings 71 is such that although the rate of water flowing into the chamber 64 is variable, the rate of flow of water through the openings 71 is substantially constant and gentle over the coffee powder.

It has been found that the use of the distributor means 60 provides brewed coffee the flavour of which is appreciably better than coffee brewed by conventional techniques. Although the exact reasons for this improvement in brewed coffee flavour have not been determined, it is believed that the gentle and constant flow of water over the entire exposed surface area of the coffee powder (and not a localised flow as in conventional machines) is an important factor.

The invention is not limited by or to the specific embodiments described which can undergo considerable variation without departing from the scope of the invention.

Claims (9)

1. An apparatus for brewing coffee which apparatus comprises a reservoir for water; means for heating the water to a temperature suitable for brewing coffee; an inlet port for cold water located at or near the base of the reservoir; an outlet port for heated water located at or near the top of the reservoir; a pipe in liquid communication with the outlet port for enabling water which flows through the outlet port to flow over coffee retained in a suitable filter thereby providing brewed coffee; means for collecting the brewed coffee; and means for controlling the input of water to the reservoir which in turn controls the flow of water through the outlet port.

2. An apparatus as claimed in claim 1 wherein the means for controlling the flow of input water comprises a valve means operatively associated with a first water level detector means located on a notional line corresponding to a level of water just below the outlet port so that when the level reaches the first detector means, a first output signal from the first detector means closes the valve means.

3. An apparatus as claimed in claim 2 wherein the valve means is operatively associated with a second water level detector means located on a notional line corresponding to a level of water at or above the outlet port; and means for deactuating the first detector means is provided so that when the first detector means is deactuated and the water level reaches the second detector means, a second output signal from the second detector means closes the valve means.

4. An apparatus as claimed in any one of claims 1-3 wherein the coffee collecting means comprises an urn housed in the reservoir.

5. An apparatus as claimed in claim 4 wherein a third liquid level detector means operatively associated with the valve means is located on a notional line corresponding to the desired maximum level of liquid in the urn so that, in use, when the liquid level reaches the third detector means, a third output signal from the third detector means closes the valve means.

6. An apparatus as claimed in any of claims 1-5 which further comprises a liquid distributor means comprising a plate member having a chamber located on one face thereof; the chamber having a side opening therein for enabling the pipe to be in liquid communication therewith; and a plurality of openings in the wall of the chamber so that, in use, with the plurality of openings located above the filter, water, which enters the chamber from the pipe, is distributed evenly over the coffee.

7. An apparatus as claimed in claim 6 wherein the number or size or both the number and size of the plurality of openings is such as to allow, in use, water to accumulate in the chamber thereby providing a constant flow of water through the plurality of openings.

8. An apparatus as claimed in claim 6 or claim 7 wherein the openings are distributed so as to provide, in use, a flow of water over substantially the entire exposed surface area of coffee in the filter.

9. An apparatus for brewing coffee substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.