Flow system delivery system and beverage machine using same

1. A flow delivery system for delivering and monitoring a liquid flow, the system comprising:

a pump;

a monitoring device for monitoring a flow generated by the pump;

a sensing arrangement for detecting the presence of a flow monitored by the monitoring device; and

a controller for determining if the detected flow is a liquid flow or a gas flow, wherein the controller is adapted to:

control the pump with a first drive signal;

in response to a detected flow which may be the gas flow, reduce a drive signal for the pump from the first drive signal to a second drive signal, thereby to change characteristics of the pump drive signal and characteristics of the resulting flow; and

based on the change in said characteristics, determine if the flow is the liquid flow or the gas flow.

2. The system as claimed in claim 1 , wherein the first drive signal is a pump drive signal intended for delivering the liquid flow at a predetermined rate, and wherein the first drive signal is a maximum pump drive signal.

3. The system as claimed in claim 1 , wherein the controller is adapted to determine if the detected flow is the gas flow by:

detecting any flow; or

determining if a flow parameter for the detected flow is below a first threshold.

4. The system as claimed in claim 1 , wherein the controller is adapted to:

in response to the detected flow which may be the gas flow, reduce the drive signal for the pump from the first drive signal to a predetermined second drive signal; and

based on a measured flow parameter when the pump is driven with the predetermined second drive signal, determine if the flow is the liquid flow or the gas flow.

5. The system as claimed in claim 1 , wherein the controller is adapted to:

in response to the detected flow which may be the gas flow, reduce the drive signal for the pump in a controlled manner from the first drive signal;

monitor a flow parameter during the progressively reducing drive signal;

determine the second drive signal as that at which the flow parameter drops to a predetermined level; and

based on the second drive signal, determine if the flow is the liquid flow or the gas flow.

6. The system as claimed in claim 1 , wherein the controller is adapted to:

in response to the detected flow which may be the gas flow, reduce the drive signal for the pump from the first drive signal to a zero drive signal; and

based on the temporal response of a measured flow parameter, determine if the flow is the liquid flow or the gas flow.

7. The system as claimed in claim 3 , wherein the monitoring device comprises a rotary member which is rotated by a flow through the monitoring device generated by the pump, and the sensing arrangement is for sensing rotation of the rotary member, thereby to detect the flow.

8. The system as claimed in claim 7 , wherein the flow parameter comprises an indication of a rotation speed of the rotary member.

9. The system as claimed in claim 8 , wherein the flow parameter comprises a characteristic of a pulse train signal generated by the monitoring device.

10. A beverage machine comprising:

a water container;

a beverage making section; and

the flow delivery system as claimed in claim 1 for delivering water from the water container to the beverage making section and for monitoring the water flow to the beverage making section,

wherein the controller is for determining when the water container is empty and for stopping the pump when the water container is empty.

11. A method for delivering a liquid flow using a pump and monitoring the liquid flow, comprising:

sensing using a flow monitoring device thereby to detect a flow; and

determining if the flow is a liquid flow or a gas flow by:

controlling the pump with a first drive signal;

detecting a flow which may be the gas flow, and in response:

reducing a drive signal for the pump from the first drive signal to a second drive signal, thereby to change characteristics of the pump drive signal and characteristics of the resulting flow; and

determining if the flow is the liquid flow or the gas flow based on the change in said characteristics.

12. The method as claimed in claim 11 , comprising, in response to detecting the flow which may be the gas flow:

reducing the drive signal for the pump from the first drive signal to a predetermined second drive signal; and

determining if the flow is the liquid flow or the gas flow based on a measured flow parameter when the pump is driven with the second drive signal.

13. The method as claimed in claim 11 , comprising, in response to detecting the flow which may be the gas flow:

reducing the drive signal for the pump in a controlled manner from the first drive signal;

monitoring a flow parameter during the reducing drive signal;

determining the second drive signal as that at which the flow drops to a predetermined level; and

based on the second drive signal, determining if the flow is the liquid flow or the gas flow.

14. The method as claimed in claim 11 , comprising, in response to detecting the flow which may be the gas flow:

reducing the drive signal for the pump from the first drive signal to a zero drive signal; and

determining if the flow is the liquid flow or the gas flow based on the temporal response of a measured flow parameter.

15. A computer storage media comprising computer program code means which is adapted, when said computer program code is run on a computer, to cause a flow delivery system implement the method of claim 11 .