Hydraulic circuit for instant beverage machines, relief and safety valve for said circuit and method for the preparation of instant beverages

1. A hydraulic circuit for beverage machines, the hydraulic circuit comprising a tank, a water extraction pipe contained in said tank, a flow-meter connected to said extraction pipe, a pump, a vibration-damping valve, a boiler, a relief and safety valve, a water/steam faucet, a beverage flow valve for delivering a beverage outside a beverage machine, a recovery tank, said relief and safety valve comprising a water/steam inlet, a first water/steam outlet directed to said faucet, a second outlet for directing pressurized water to said beverage flow valve and a third outlet for discharging water into the recovery tank, said third outlet being controlled by a solenoid valve equipped with a control coil, wherein said solenoid valve is equipped with a first maximum pressure limiting device, wherein said second outlet is provided with a second maximum pressure limiting device for directing the pressurized water to the beverage flow valve, and wherein said second outlet has an inlet which is provided with a valve equipped with a third maximum pressure limiting device which enables passage of liquid in order to release pressure from the beverage flow valve.

2. The hydraulic circuit of claim 1 , wherein said first maximum pressure limiting device comprises a first pre-calibrated spring.

3. The hydraulic circuit of claim 1 , wherein said second maximum pressure limiting device comprises a second pre-calibrated spring.

4. The hydraulic circuit of claim 1 , wherein said third maximum pressure limiting device comprises a third pre-calibrated spring.

5. The hydraulic circuit of claim 1 , wherein said relief and safety valve is of the “slide” type.

6. The hydraulic circuit of claim 1 , wherein said faucet comprises an inlet, a first outlet, a second outlet, a faucet lever for selecting one of the first outlet and the second outlet, a support provided with sensors for detecting the position of said faucet lever, and a slider capable of opening and closing passages of said faucet.

7. The hydraulic circuit of claim 6 , wherein said faucet is provided with a device for determining the position of said slider.

8. The hydraulic circuit of claim 7 , wherein said device for determining the position of said slider comprises at least one REED sensor and at least one magnet.

9. The hydraulic circuit of claim 1 , wherein the first maximum pressure limiting device remains closed during normal operation and opens up if pressure exceeds a specific threshold, or if a specific command is sent to the control coil of said solenoid valve.

10. The hydraulic circuit of claim 1 , wherein the first maximum pressure limiting device comprises a first pre-calibrated spring calibrated at about 16/20 bars, wherein the second maximum pressure limiting device comprises a second pre-calibrated spring calibrated at about 3 bars, wherein the third maximum pressure limiting device comprises a third pre-calibrated spring calibrated at about 0.2 bars.

11. The hydraulic circuit of claim 1 , wherein the control coil of the third outlet is configured to be energized with a command and with a spring calibrated at about 16/20 bars.