AU2015101973A4 - Espresso machine - Google Patents

Abstract

Described herein is a coffee machine that comprises a water reservoir, a group head assembly, a brew path arrangement between the water reservoir and the 5 group head assembly, and a controller. The group head assembly is adapted to receive a coffee filter cradle. The brew path arrangement provides fluid communication between the water reservoir and the group head assembly. The brew path arrangement comprises a pump for pumping water from the water reservoir to the group head assembly, a first thermoblock configured to preheat 10 water passing through the first thermoblock, and a first temperature sensor associated with the first thermoblock. The brew path arrangement further comprises a second thermoblock downstream of the first thermoblock configured to heat water passing through the second thermoblock, and a second temperature sensor associated with the second thermoblock. The brew path 15 arrangement also comprises at least one inline sensor, downstream of the pump, providing at least one of water temperature and flow parameters along the brew path arrangement. The controller is responsive to the temperature and inline sensors and is adapted to regulate the temperature of water at the group head assembly in response to sensor measurements from one or more of the 20 temperature and inline sensors.

Description

Espresso Machine

Field of the invention

The invention relates to an espresso type coffee machine.

Background of the invention

Espresso coffee machines are used to produce espresso coffee and related hot beverages. Such machines produce hot water for making coffee and also produce steam, for example via a steam wand, which may be used to steam milk. In addition, the coffee machine may dispense hot water.

There has been an increasing demand for coffee machines that produce high quality coffee to the extent that many households now have a domestic coffee machine. To satisfy this demand, manufacturers of coffee machines have sought to supply coffee machines that are affordable to many households, but still produce high quality coffee. Factors that influence the quality of coffee being brewed include the grind of the coffee, the density of the coffee in the filter, and both the temperature and the pressure of the water dispensed through the group head.

Various types of configurations of coffee machines have been proposed in the past. However, there remains a demand for coffee machines that may be suited to domestic use that produce quality coffee.

It would be desirable to provide a domestic coffee machine with improved functionality, or alternatively to provide the public with a useful alternative to existing coffee machines.

Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.

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Summary of the invention

In one aspect the invention provides a coffee machine comprising: a water reservoir;

a group head assembly adapted to receive a coffee filter cradle;

a brew path arrangement providing fluid communication between the water reservoir and the group head assembly, the brew path arrangement comprising: a pump for pumping water from the water reservoir to the group head assembly; a first thermoblock configured to preheat water passing through the first thermoblock; a first temperature sensor associated with the first thermoblock; a second thermoblock downstream of the first thermoblock configured to heat water passing through the second thermoblock; a second temperature sensor associated with the second thermoblock; and at least one inline sensor, downstream of the pump, providing at least one of water temperature and flow parameters along the brew path arrangement; and a controller responsive to the temperature and inline sensors and adapted to regulate the temperature of water at the group head assembly in response to sensor measurements from one or more of the temperature and inline sensors.

The temperature of the water may be regulated by controlling at least one of: the temperature of the first thermoblock, the temperature of the second thermoblock and the flow rate of the water.

The at least one inline sensor may comprise a downstream inline temperature sensor downstream of the second thermoblock. The at least one inline sensor may comprise an upstream inline temperature sensor between the first thermoblock and the second thermoblock. The inline temperature sensors may be negative temperature coefficient (NTC) sensors. The at least one inline sensor may further comprise a flow meter.

The controller may comprise memory and may further be adapted to: store sensor measurements obtained during one or more coffee pours, process the stored sensor measurements to determine a trend or average parameter, and in response to the trend or average parameter, adjust at least one of: a specified temperature threshold of at least one of the temperature sensors, and the flow rate of the water.

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The coffee machine may further comprise: a steam outlet; and a steam path comprising a steam thermoblock and providing fluid communication between the water reservoir and the steam outlet; wherein the coffee machine further comprises a preheated water path from the first thermoblock to the steam thermoblock for providing 5 preheated water to the steam thermoblock.

The coffee machine may further comprise a hot water outlet providing hot water from one of a group consisting of: the steam thermoblock, the first thermoblock, and the second thermoblock.

As used herein, except where the context requires otherwise, the term I0 comprise and variations of the term, such as comprising, comprises and comprised, are not intended to exclude further additives, components, integers or steps.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following 15 description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

Figure 1 shows a front perspective view of a first embodiment for an espresso coffee machine;

Figure 2 shows a functional block diagram of a heating system used in the 20 espresso coffee machine of Figure 1;

Figure 3A shows a diagram of plumbing components suitable for use with the coffee machine of Figure 1;

Figure 3B shows a control flow diagram of the embodiment shown in Figure 3A;

Figure 4 shows a diagram of plumbing components according to another 25 embodiment;

Figure 5 shows a diagram of plumbing components according to yet another embodiment;

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Figure 6 shows a diagram of plumbing components according to a further embodiment;

Figure 7 shows a diagram of plumbing components according to another embodiment;

Figure 8 shows a diagram of plumbing components according to a further embodiment;

Figure 9 shows a graph comparing the temperature in the group head assembly when no active control is used with the temperature in the group head assembly with active control using temperature sensors.

I0 Detailed description of the embodiments

Referring to Figure 1, an espresso coffee machine 100 has a base 102 and a body 104. The base 102 supports a collection tray 106 (such as a drip tray). The body 104 houses a water reservoir 118 which in this instance is a drawer which may be slid in/out of the body 104. On the top of the body 104 is a surface 108 which may be used 15 to store cups, saucers and other implements. In some embodiments the surface 108 may be warmed.

The machine 100 has a group head assembly 110 which includes a group head outlet through which hot water is dispensed under pressure in order to make coffee. The group head assembly 110 receives a removable filter assembly 150. The machine 100 20 includes a steam outlet, in the form of a steam wand 112. The machine 100 can be operated by a user to vent steam through the steam wand 112 which can be used, for example, to heat liquid such as milk. The steam wand 112 is pivotally and rotationally attached to the machine 100 to allow the end of the steam wand 112 to be easily manoeuvrable relative to the machine 100. The steam wand 112 may include a 25 temperature sensing device (not shown) that senses the temperature of any liquid being steamed by the steam wand 112. The temperature sensor may be in communication with an electronic controller 200 (described below with reference to Figure 2) and may then transmit the sensed temperature thereto to allow the controller 200 to display the sensed temperature and/or automatically control operation of the steam wand 112. The

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2015101973 07 May 2015 machine 100 also includes a hot water outlet 114, in the form of a hot water wand, via which a controlled flow of hot water can be dispensed.

The machine 100 has a control panel 130 which includes a display 132. The display 132 is connected to the electronic controller 200 and can be controlled to display 5 a variety of operational parameters of the machine 100. By way of non-limiting example, the display 132 may be controlled to display information regarding one or more of: an operational setting selected by the user; water pressure; water temperature; the water level of the reservoir 118; an estimated time until the machine 100 is ready for use; the temperature of liquid being steamed via the steam wand 112; the temperature of a I0 steam outlet path heater; the temperature of one or both brew path heaters; the flow rate of a steam outlet path pump; the flow rate before and/or after the brew path pump; and error or maintenance messages. Display 132 may, for example, include one or more LCD screens, LED screens, LEDs, dials or similar. Display 132 may display multiple different operational parameters of the machine 100 at the same time, and/or 15 may provide controls (discussed below) which allow a user to scroll or otherwise navigate through different display screens on which different information is shown.

The control panel 130 includes an analogue dial display 140 which may be a mechanical pressure display linked directly to a pressure sensor (not shown) in order to display the pressure sensed at the group head as coffee is being dispensed.

The machine 100 includes a plurality of user controls by which a user controls operation of the machine 100. In this instance the user controls include a plurality of push buttons 134 which are connected to the controller 200 and which, when activated by the user, cause the controller 200 to perform a variety of tasks. For example, push buttons 134 may include: a single shot button, which causes the controller to operate 25 the machine 100 to supply sufficient water through the group head assembly 110 to prepare one shot of coffee; a two shot button, which causes the controller to supply sufficient water through the group head assembly 110 to prepare two shots of coffee; and a water start/stop button which causes the controller to start/stop water flow through the group head assembly 110. The control buttons 134 may also include navigation 30 controls (e.g. up, down, left, right controls) for scrolling through different display options on the display 132. In some embodiments such navigation buttons may also or

700015408 alternatively allow a user to scroll through various control options, as described above, which are displayed on the display 132, and select a desired control option by an “enter” button or similar.

The user controls also include a steam control dial 116 which when operated by the user allows steam to be vented through the steam wand 112, and a hot water control dial (not shown) which when operated by the user allows water to be provided through the hot water outlet 114. These control dials may, for example, be either solenoid valves or mechanical taps which allow for either direct manual operation or indirect operation via the controller 200. In alternative embodiments, steam and water flow through the steam and hot water outlets may be directly or indirectly (i.e. via the electronic controller 200) controlled by other control interfaces such as buttons.

In some embodiments, in addition to the control panel 130 described above, the user interface of the machine 100 includes a communication interface to connect wirelessly (e.g. via Bluetooth or Wi-Fi) to a user’s mobile device, such as a smartphone. The mobile device includes an application that is used to select and/or customise extraction profiles including pressure, time, volume and temperature. The mobile device application also allows a user to select the brand and roast of coffee beans being used and to download from the Internet the best extraction profile for that particular roast. Feedback from the machine 100 to the mobile device application is provided on the extraction process providing recommendations for improvement, if required, as well as recording and displaying a detailed history of each extraction including the number of shots, name of extraction profile, date and time of shots, extraction analytics (pressure, time, water flow, volume and temperature). Content such as images, video, advertising and text may also be downloaded onto the espresso machine from the mobile device.

In some embodiments the user interface (including the control panel 130 and/or the mobile device application) enables a user to adjust the extraction profile, either as a preset profile or in real-time during operation of the machine 100. This user-adjustable extraction profile may be one or more of a temperature profile, a pressure profile, or a flow rate profile. All profiles are adjustable over time (e.g. over the 30 second duration of an average pour) or over volume (e.g. over the 42ml of an average single shot pour). The temperature profile is adjustable over a possible range of 0-100 degrees Celsius

700015408 range, preferably from 90-95 degrees, more preferably over a 92-93 degrees Celsius range. The pressure profile is adjustable over a 0-18 bar range, preferably over a 5-15 bar range. The flow rate profile is adjustable over a 0-10 ml/s range (for example, dependent on the coffee brew method used), preferably over a 0,25-1,5 ml/s range for espresso.

Further components of the coffee machine 100 will now be described generally with reference to Figure 2, before being described in more specific detail (and with reference to specific embodiments) with reference to Figures 3 to 9.

Coffee machine 100 includes an electronic controller 200 which is in communication with various components of the machine 100 (such as the user controls, the display, pumps, heaters, sensors, flow meters and valves). The controller 200 is programmed to control operation of the components of the machine 100 in order to operate the coffee machine 100 in accordance with the user input via the user controls. The machine 100 also includes a power supply (not shown) which supplies power to the electronic controller 200 and other relevant components of the machine 100 (e.g. the user controls, display, heaters, pumps, sensors, flow meters and valves).

The wattage rating of the power supply is typically 2,000-3,000W, preferably 2,400W at 240VAC. To avoid a total current draw in excess of 10A a current limiting device is used. This can be a circuit breaker to be reset by a user, a self-held circuit breaker that resets once power is removed from the machine, or a current fuse that is user replaceable.

As described herein, the controller 200 includes a proportional-integral-derivative (PID) controller. The PID controller is implemented using a suitable controller (such as a microcontroller) or processor (such as a microprocessor or digital signal processor, DSP). The controller 200 also includes memory used to store data (e.g. sensor measurement data) before, during and after processing.

The coffee machine 100 includes two independent flow paths leading from the water reservoir 118: a path by which steam is supplied to the steam wand 112, referred to as the steam path 202; and a path by which water is supplied to the group head 110,

700015408 referred to as the brew path 204. As described below, each path includes a dedicated pump, heating system, and plumbing (pipes and valves).

The steam path 202 includes a steam path pump 206, a pressure release valve 208, a water heater, in this case a steam thermoblock 210, and a steam valve 212. The brew path 204 has a first flow meter 214 followed by a brew pump 216. Optionally a second flow meter 218 may be included in the brew path 204 after the brew pump 216. The flow parameters received from the first and/or second flow meters 214, 218 provide an indication of the flow rate in the brew path 204.

The first flow meter 214 used in the brew path 204 of each of the embodiments may suitably be a Digmesa® digital flow meter which includes a rotor rotated by the flow of water and converts movement of the rotor into a digital signal. Alternative flow meters, such as the Digmesa® laser flow meter, are of course possible. In embodiments where a second flow meter 218 is used (for example as shown in Figures 4 and 5), the second flow meter 218 is a high pressure flow meter, for example a Sensirion™ SLG64flow meter.

Following the flow meters 214, 218, the brew path 204 then includes two brew path heaters, 220, 224, both being thermoblocks. The first brew path thermoblock 220 preheats the water to the appropriate brew temperature (typically 92 degrees Celsius) or a temperature close to the brew temperature (for example 80-90 degrees Celsius). This is typically a 700-1200W thermoblock, for example a 900W thermoblock. The second brew path thermoblock 224 receives the preheated water and finishes the heating process by ensuring that the water is heated to the appropriate brew temperature, for example 92 degrees Celsius. The second brew path thermoblock 224 is typically a 150-350W thermoblock, for example a 200W thermoblock.

In some embodiments both brew thermoblocks are the same, for example two 1100W thermoblocks may be used. In such embodiments a power share arrangement is used, whereby a proportion of a total 1100W supplied by the power source to the two thermoblocks is provided to the first brew thermoblock (e.g. 900W) and a proportion of the 1100W total power is provided to the second brew thermoblock (e.g. 200W). This power share arrangement is implemented at times when the steam thermoblock is

700015408 simultaneously available, for example during a coffee pour. When use of the steam thermoblock is disables (for example during the initial heat up of the machine before standby temperatures have been reached), the power supply provides 1100W to both brew thermoblocks.

Each brew path heater is provided with a casting negative temperature coefficient (NTC) sensor that measures the temperature of the casting of each thermoblock heater, thereby providing an estimate of the water temperature. The first casting temperature sensor 222 is associated with the first thermoblock 220, and the second casting temperature sensor 226 is associated with the second thermoblock 224. Optionally, one or more additional inline sensors may be used after the first and/or second heater to measure the temperature of the water.

Both the casting and inline NTC sensors are suitably fast response thermistors. An example of an NTC sensor that can be used is the 104H-CT-4-4267G Sensorbase™ NTC thermistor.

Use of a thermoblock to generate hot water (for the group head assembly 110 and/or hot water outlet 114) and/or steam for the steam wand 112 can be advantageous for a number of reasons. For example thermoblocks heat up from ambient temperature faster than boilers do so that the machine is ready for use quicker; output water from a thermoblock is always fresh because a typical thermoblock holds only about 15ml at a time, while boilers hold 300ml or more so that fresh water mixes with water already in the boiler; thermoblocks are easy to decalcify by pumping a decalcification solution from the water reservoir 118; and thermoblocks are generally less costly than boilers and can be relatively easily replaced or repaired in the event of malfunction or failure. Further, thermoblocks are capable of good temperature control and can provide a constant supply of hot water or steam (provided, of course, water reservoir 118 does not empty).

As shown in Figure 2, sensor measurements 230 are provided to the controller 200 from one or more of the various flow meters and temperature sensors. The controller 200 processes the temperature measurements (and in some embodiments in conjunction with the flow parameter(s) received from one or both flow meters) to determine a temperature parameter. The temperature parameter may include, for

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2015101973 07 May 2015 example, the difference between a temperature sensor’s specified temperature threshold (e.g. 92 degrees Celsius) and the measured temperature, or the difference between a flow rate threshold and the measured flow rate at one or both of the flow meters. In response to the temperature parameter, the controller 200 regulates the 5 water temperature in the brew path by adjusting the operation of the brew pump 216, the temperature of the first thermoblock 220, and/or the temperature of the second thermoblock 224. The pump 216 and thermoblocks 220, 224 are controlled using fast Triode for Alternating Current (TRIAC) switches that are fast enough so that the pump 216 and/or thermoblocks 220, 224 are controlled fast enough so that the water I0 temperature is maintained at the desired temperature during the time that a 1 or 2 shot brew is poured (typically 20-30±5 seconds, preferably 25±5 seconds). Preferably, a response time within 5-10 seconds is required.

When a user wishes to make coffee, the controller 200 operates the pump 216 to pump the required volume of water (e.g. 30ml for 1 shot, 60ml for 2 shots) through the 15 brew path thermoblocks 220, 224. The heated water is then pumped under pressure through the outlet in the group head assembly 110. The first flow meter 214, and optionally the second flow meter 218, measure the volume of water pumped by the brew path pump 216, and the pressure in the brew path 204 can be calculated by the controller 200 with reference to the volume of water flowing through the flow meter(s) 20 over time. The calculated pressure can be displayed by the controller 200 on display 132. One or more pressure sensors (not shown) may be provided in the brew path 204 to allow pressure in the brew path 204 to be directly reported to the controller 200. The pump is then controlled dependent on the sensed pressure to obtain water pressure between 0 and 15 bar, preferably between 9 and 12 bar. In some embodiments the 25 measured pressure is displayed on the user interface, for example on the display 132 or on the analogue dial display 140.

The brew path 204 includes a dump valve 228. Once coffee has been made, the dump valve 228 can be operated (typically automatically by the controller as part of the coffee cycle) to relieve pressure in the brew path 204 by dumping excess water in the 30 plumbing to the collection tray 106.

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Π

In each of the embodiments the steam valve 212 in the steam path 202 and dump valve 228 in the brew path 204 may, for example, be either solenoid valves or mechanical taps. These may be either directly and manually operable by a user (for example by turning a handle of the tap or similar). Alternatively the valves 212, 228 may be indirectly operated by the user by activation of a control (e.g. a button or dial) which sends a signal to the controller 200 which, in turn, operates the relevant valve/tap. Alternatively the valves 212, 228 may be automatically operated by the controller 200 as part of a broader user command (e.g. making coffee or similar), or in response to the pressure exceeding a predetermined value.

As noted above, the machine 100 may also include a hot water outlet 114 for dispensing hot water, not shown in Figure 2. The machine 100 may be configured to feed the hot water outlet 114 from either the steam thermoblock 210 or either of the brew path heaters as described below with reference to Figures 3-8.

For both the steam path 202 and the brew path 204 copper piping may be used.

Operation overview

To set up the coffee machine 100, the water reservoir 118 may be removed from the machine 100 to be filled, or filled in situ via the funnel. The correct size filter is selected for the intended purpose (i.e. a single shot filter or double shot filter 156), placed inside the filter cradle of the filter assembly 150, and filled with ground coffee and tamped. The filter assembly 150 is then secured to the machine 100 by securing it into the bayonet collar of the group head assembly 110.

When the machine 100 is turned on the controller 200 supplies power to the resistive elements of the heaters 210, 220 and 224. Once the heaters 210, 220 and 224 reach their respective standby temperatures, the machine 100 is ready to use. At this point the controller 200 may cut power to the heaters 210, 220 and 224 (and resupply power thereto if the temperature of the heaters 210, 220 and 224 falls below a threshold value). The user may be alerted to readiness of the machine 100 via display 132.

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To make coffee, a user activates the relevant control button 134 - e.g. one shot, two shots, or manual operation. On receiving either a one or two shot command, the controller 200 operates the brew path pump 216 to pump the desired volume of water under pressure to the outlet of the group head assembly 110 through the brew path 204 (where it is forced through coffee grounds in the filter assembly 150, and into a cup).

Alternatively, a user may select manual operation, in which case the controller 200 operates pump 216 to continuously pump water to the outlet of the group head assembly 110 until the user inputs the command to stop (e.g. by pressing the same button again) or until a manual operation time threshold is reached. After the selected volume of water has been pumped the controller 200 turns off pump 216.

To produce steam the user activates the steam control (e.g. a steam dial or button). This both opens the steam valve 212 in the steam path 202 and causes the controller 200 to activate the steam path pump 206 and control the steam thermoblock 210 to heat the water to approximately 170°C (+/- 5°C). Water is pumped through the heater 208 where it is heated to steam, and then vented via the steam wand 112. When the user wishes to stop the production of steam, the steam dial is turned in the opposite direction (or the relevant button activated), and the controller 200 ceases operation of the steam path pump 206 and reduces the steam thermoblock 210 temperature to the standby temperature.

If the user elects to produce hot water via the water outlet 114 the controller operates the relevant pump (206 or 216) and heater (210, 220 or 224) depending on whether the machine 100 is configured to deliver water via the steam path 202 or the brew path 204 as described below. The water is pumped through the relevant heater to heat it to the pre-set temperature for hot water and out of the hot water outlet 114.

Specific embodiments of the invention

Referring to Figures 3 to 8, specific embodiments of the general machine architecture outlined above will be described. In Figures 3 to 8, reference numerals from Figures 1 and 2 have been adopted for the relevant components of the coffee machine 100 for ease of reference.

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Embodiment 1 - temperature sensors

Referring to Figure 3A, a first specific embodiment 300 of a coffee machine 100 having a two-stage heating system is shown. In this embodiment: the steam path pump 206 is a vibration pump; the steam heater 210 is a thermoblock; the brew path pump 216 is a vibration pump; and both the first brew path heater 220 and the second brew path heater 224 are thermoblocks. In some embodiments the steam thermoblock 210 may be a boiler. The brew path pump 216 may include a cavitation relief valve 322 to assist in priming the pump and avoiding cavitation by providing an optional flow path back to a T-joint (indicated in dashed lines) where water is pumped back through the brew path pump 216.

In the embodiments described herein a vibration pump is used for both the steam path pump 206 and the brew path pump 216. Vibration pumps, also referred to as solenoid pumps, such as those manufactured by Ceme (Ulka) or China Star are suitable for use in these embodiments. Vibration pumps are advantageous in that they are relatively inexpensive components which are capable of meeting the usage requirements of an espresso machine. In addition, they do not readily cavitate and are able to maintain high pressure.

In these embodiments, the vibration pumps will advantageously be located such that their water inlets are located below the water reservoir 118. Provided the water reservoir 118 does not run dry, this ensures that the pumps are always flooded, which in turn reduces the likelihood of cavitation.

In some embodiments rotary vane pumps may be used such as those manufactured by Procon (e.g. the Procon Micro PRO RV pump). Rotary vane pumps can be advantageous as they operate relatively quietly, provide a relatively constant flow and, typically, have a long life. Also, rotary vane pumps are capable of providing essentially instant and consistent pressure which can typically be adjusted (e.g. by adjustment of a build-in screw or similar provided on the pump). In addition, and as with vibration pumps, rotary vane pumps do not readily cavitate and are able to maintain a relatively high pressure.

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In the brew path 204 shown in Figure 3A, the brew path arrangement includes a first, upstream, flow meter 214, the brew path pump 216 with a cavitation relief valve 322, and then two thermoblocks that lead to the group head assembly 110. The first thermoblock 220 preheats the water to a preheat temperature of between 80 and 100 degrees Celsius, preferably between 85 and 95 degrees Celsius, more preferably approximately 92 degrees Celsius. The first thermoblock 220 has a temperature sensor 222, for example a casting NTC sensor, that measures the temperature of the thermoblock. The second thermoblock 224 further heats the preheated water to a brew temperature of between 90 and 95 degrees Celsius, preferably to maintain it at approximately 92 degrees Celsius. The second thermoblock 224 has a temperature sensor 226, for example a casting NTC sensor, that measures the temperature of the thermoblock.

The embodiment shown in Figure 3A has two inline temperature sensors. The first inline temperature sensor 332 is between the first and second thermoblock, and measures the water temperature between the thermoblocks. The second inline temperature sensor 334 is downstream of the second thermoblock 334, adjacent the valve 330 that provides the hot water for brewing to the group head assembly 110. (As described above, three way valve 330 is also operable to control the flow of water to the hot water outlet 114.)

Sensor measurements from the second inline temperature sensor 334 are used by the controller 200 to regulate the temperature of the water so that the hot water for brewing that is provided to the group head assembly 110 is the appropriate temperature, for example 92 degrees Celsius. The controller adjusts the power to the pump 216, and/or the temperature of one or both of the thermoblocks 220, 224 in order to regulate the water temperature.

In other embodiments, a combination of sensor measurements from one or more of the flow meter 214, the casting NTC temperature sensors, 222, 226 or the inline NTC temperature sensors 332, 334 may be used by the controller 200 to regulate the temperature of the water.

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The operation of this embodiment may be further understood with reference to the flow diagram 340 in Figure 3B.

After the coffee machine 100 is switched on at step 342, both the first thermoblock 220 and the second thermoblock 224 are heated up at step 344. At step 5 346 both the casting temperature sensors 222, 226 provide temperature sensor measurements to the controller 200 (for example a PID controller) which in turn controls one or more TRIAC switches to adjust the temperature of one or both of the thermoblocks 220, 224 based on the sensors’ specified temperature thresholds. Step 348 assesses whether the standby temperature of each of the thermoblocks 220, 224 I0 has reached each sensor’s specified temperature threshold. Typically this would be between 90 and 100 degrees Celsius for both thermoblocks, for example 92 degrees Celsius. Once the standby temperature has reached the specified temperature threshold for each thermoblock, standby mode is maintained at step 350 by the casting temperature sensors 222, 226 and the controller 200. Once the coffee pour user input is 15 received at step 352, ambient temperature water is pumped from the water reservoir 118 to the first thermoblock 220 by the brew pump 216 at step 354.

Step 356 monitors and regulates the water temperature during the coffee pour. In particular:

i) The first inline temperature sensor 332 provides temperature sensor 20 measurements to the controller which are used to control the power to the element of the first thermoblock 220 so that the output temperature of the water is approximately the same as the specified temperature threshold, for example 92 degrees Celsius.

ii) The first casting temperature sensor 222 provides temperature sensor measurements to the controller which are used to control the power to the element of the first thermoblock so that the temperature of the thermoblock 220 does not exceed 100 degrees Celsius.

iii) The second inline temperature sensor 334 provides temperature sensor measurements to the controller which are used to control the power to the element of the second thermoblock 224 so that the output temperature of the water is

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2015101973 07 May 2015 approximately the same as the specified temperature threshold of sensor 334, for example 92 degrees Celsius.

iv) The second casting temperature sensor 226 provides temperature sensor measurements to the controller 200 which are used to control the power to the element 5 of the second thermoblock 224 so that the temperature of the thermoblock 224 does not exceed 100 degrees Celsius.

In some embodiments step 356 may further include a machine learning process.

The machine learning process entails storing sensor measurements obtained during one or more coffee pours (for example 2, 3, 4, 5 or more coffee pours), and then I0 processing the temperature measurements from the second inline sensor 334 to determine a trend or average parameter. The trend or average parameter may include, for example, an average difference between the specified temperature threshold (e.g.

degrees Celsius) and the actual temperature, ΔΤ, or an average difference between an optimal flow rate and the measured flow rate at one or both of the flow meters. The 15 average values are calculated over the preceding one or more coffee pours (for example 2, 3, 4, 5 or more). In response to this trend or average parameter, the controller 200 adjusts the specified temperature threshold of one or both of the thermoblocks.

Step 358 assesses whether the required volume of coffee has been poured and 20 once coffee pour has ceased at step 360 the machine returns to standby mode at step 350 until another pour is initiated at step 352, or until the machine is switched off.

Figure 9 is a graph 900 showing three temperature measurements taken at the middle of the coffee cake:

902 - when a single casting temperature sensor on a single thermoblock is used;

904 - when the thermoblock temperatures are controlled by casting sensors on both thermoblocks during standby and coffee pour; and

906 - when the thermoblock temperatures are controlled by casting sensors on both thermoblocks during standby and controlled by inline sensors at both thermoblock during coffee pour.

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The increased temperature stability achieved with the use of temperature sensors used in controlling the temperature can be seen, for example approximately 10 seconds into the first brew. In particular, when only a single casting temperature sensor is used (902), the temperature undergoes an initial dip 908 as the pour starts before recovering, and then after recovery does not reach the desired 92 degrees. However, where both thermoblocks have temperature sensors (with or without inline sensors) the temperature measured in the coffee cake is very close to, or at, the desired 92 degrees throughout the initial 25 seconds that the water is poured. (Note the temperature drop after about 55 seconds is when the coffee cake is removed from the filter.)

Embodiments 2 and 3 - two flow meters

Figure 4 shows a second embodiment 400 of an espresso coffee machine 100. Otherwise similar to the first embodiment 300 shown in Figure 3A, the second embodiment 400 includes an additional second flow meter 218 downstream of the brew pump 216 that provides a downstream flow rate measurement to the controller 200. The controller 200 uses the downstream flow rate measurement in conjunction with the temperature measurements from the inline temperature sensors 332, 334 to determine the temperature parameter used to regulate the water temperature by controlling one or more of the brew pump 216, the first thermoblock 220 and the second thermoblock 224.

In the third embodiment 500 shown in Figure 5, two flow meters are used as in embodiment 400, the first flow meter 214 and the second flow meter 218. As shown, only the casting temperature sensors 222, 226 are used, and no inline temperature sensors.

It will be appreciated that various combinations of casting temperature sensors, inline temperature sensors, and flow meters may be used to provide sensor measurements to the controller 200 for use in controlling the operation of the machine 100 and for regulating the temperature of the water in the brew path. For example, in some embodiments an additional inline temperature sensor may be used before the first thermoblock 220 to measure the input water temperature.

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The operation of these embodiments is similar to the operation of the first embodiment as described above with reference to Figures 3A and 3B. In addition, the two flow meters contribute to the following additional control parameters.

The temperature sensors (casting and inline) provide temperature measurements used in conjunction with the flow meter measurement(s). If the temperature measurement falls within a temperature interval around the sensor’s specified temperature threshold, for example if the inline temperature sensor 334 measures between 90 and 94 degrees Celsius, then the flow rate as measured (for example by the second flow meter 218) is used to adjust the power to the element(s) of the first and/or second thermoblocks 220, 224. If the measured flow rate is above a first flow rate threshold then the power to the element(s) is switched on, and if the measured flow rate is below the first flow rate threshold then the power to the element(s) is switched off.

The measured flow rate may also be used to adjust the specified temperature threshold for one or more of the temperature sensors. In particular, if the flow rate is above a second flow rate threshold then the specified temperature threshold(s) can be increased to anticipate a resultant drop in temperature from fast flowing water. Likewise, if the flow rate is below the second flow rate threshold then the specified temperature threshold(s) can be decreased to anticipate a resultant rise in water temperature.

The first and second flow rate thresholds may be the same.

The measured flow rate may also be used to control the rate of the brew pump 216 for obtaining a repeatable and predictable water flow during the coffee pour. This allows the thermoblock(s) to ramp up temperature in proportion to the flow rate.

Embodiments 4 and 5 - hot water outlet

Figure 6 shows a fourth embodiment 600 of a coffee machine 100. In terms of temperature control in the brew path, the third embodiment 600 includes a first flow meter 214, two casting temperature sensors 222, 226 and two inline temperature sensors 332, 334. In this embodiment, the hot water outlet 114 is provided from the

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2015101973 07 May 2015 steam thermoblock 210 via a three way valve 602 (for example a solenoid valve) which is operable to control the flow of water to the hot water outlet 114.

In a fourth embodiment 700 shown in Figure 7, the hot water outlet 114 is provided from the first thermoblock 220 via a three way valve 702 (for example a 5 solenoid valve) which is operable to control the flow of water to the hot water outlet 114.

Embodiment 6 - steam turbocharge

Figure 8 shows a sixth embodiment 800 of a coffee machine 100. The configuration shown in Figure 8 is used to preheat at least some of the water provided to the steam thermoblock 210. The steam thermoblock 210 receives water from the I0 water reservoir 118 via the steam path pump 206. The steam thermoblock 210 also receives water from the first thermoblock 220 via a preheated water path 804 connected to the first thermoblock 220 via a three way valve 802 (for example a solenoid valve).

It will be understood that the invention disclosed and defined in this specification 15 extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims (9)

1. A coffee machine comprising:

a water reservoir;

a group head assembly adapted to receive a coffee filter cradle;

a brew path arrangement providing fluid communication between the water reservoir and the group head assembly, the brew path arrangement comprising:

a pump for pumping water from the water reservoir to the group head assembly;

a first thermoblock configured to preheat water passing through the first thermoblock;

a first temperature sensor associated with the first thermoblock;

a second thermoblock downstream of the first thermoblock configured to heat water passing through the second thermoblock;

a second temperature sensor associated with the second thermoblock; and at least one inline sensor, downstream of the pump, providing at least one of water temperature and flow parameters along the brew path arrangement; and a controller responsive to the temperature and inline sensors and adapted to regulate the temperature of water at the group head assembly in response to sensor measurements from one or more of the temperature and inline sensors.

2. The coffee machine of claim 1 wherein the temperature of the water is regulated by controlling at least one of: the temperature of the first thermoblock, the temperature of the second thermoblock and the flow rate of the water.

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3. The coffee machine of claim 1 or claim 2 wherein the at least one inline sensor comprises a downstream inline temperature sensor downstream of the second thermoblock.

4. The coffee machine any one of the preceding claims wherein the at least one inline sensor comprises an upstream inline temperature sensor between the first thermoblock and the second thermoblock.

5. The coffee machine of claim 3 or claim 4 wherein the inline temperature sensors are negative temperature coefficient (NTC) sensors

6. The coffee machine of any one of the preceding claims wherein the at least one inline sensor further comprises a flow meter.

7. The coffee machine of any one of the preceding claims wherein the controller comprises memory and is further adapted to:

store sensor measurements obtained during one or more coffee pours, process the stored sensor measurements to determine a trend or average parameter, and in response to the trend or average parameter, adjust at least one of: a specified temperature threshold of at least one of the temperature sensors, and the flow rate of the water.

8. The coffee machine of any one of the preceding claims wherein the coffee machine further comprises:

a steam outlet; and a steam path comprising a steam thermoblock and providing fluid communication between the water reservoir and the steam outlet;

wherein the coffee machine further comprises a preheated water path from the first thermoblock to the steam thermoblock for providing preheated water to the steam thermoblock.

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9. The coffee machine of any one of the preceding claims wherein the coffee machine further comprises a hot water outlet providing hot water from one of a group consisting of: the steam thermoblock, the first thermoblock, and the second thermoblock.