Device for varying the pressure of the fluid delivered by a jet washer

1. A jet washer comprising a positive-displacement pump operated by a single-phase electric motor powered by alternating current through a feed circuit and having a pressurized fluid delivery conduit and an electronic device which controls and regulates the delivered pressure of said pressurized fluid by regulating the motor feed voltage so as to vary the motor's speed of rotation by varying the waveform of the electric motor feed voltage, wherein said electronic device comprises at least one diode and at least one selector switch for connecting said diode into the motor feed circuit.

2. The jet washer as claimed in claim 1 , characterised by comprising at least one capacitive filter.

3. A jet washer comprising a positive-displacement pump operated by a single-phase electric motor powered by alternating current through a feed circuit and having a pressurized fluid delivery conduit and an electronic device operated by a user which controls and regulates the delivered pressure of said pressurized fluid by regulating the motor feed voltage so as to vary the motor's speed of rotation by varying the waveform of the electric motor feed voltage, wherein said electronic device comprises at least one triac, the triggering of which is controlled by a pilot circuit.

4. The jet washer as claimed in claim 3 , characterised in that said pilot circuit comprises a diac, the inhibition or conduction state of which is controlled by a timer circuit.

5. The jet washer as claimed in claim 4 , characterised in that said timer circuit comprises at least one potentiometer.

6. The jet washer as claimed in claim 4 , characterised in that said potentiometer can be adjusted by the user on the basis of the desired pressure of the fluid delivered by the pump.

7. The jet washer as claimed in claim 3 , characterised by comprising at least one ohmic-capacitive filter.