Piezoelectric injector drive circuit

A drive circuit for a piezoelectric injector, said drive circuit comprising:

• a voltage input for receiving a voltage signal;
• a bidirectional current path coupled to a piezoelectric injector;
• an inductor coupled in series with the piezoelectric injector in the bidirectional current path;
• and
• switching circuitry for controlling current flow through the piezoelectric injector and the inductor to open and close the piezoelectric injector, wherein the switching circuitry causes a first current to flow through the bidirectional current path while charging the injector, and further causes a second current opposite to the first current to flow in the bidirectional current path to discharge the injector.

A drive circuit for a piezoelectric fuel injector, said drive circuit comprising:

• a voltage input for receiving a voltage signal;
• an energy storage device coupled to the voltage input for storing an electrical charge;
• a bidirectional current path coupled to a piezoelectric fuel injector;
• an inductor coupled in series with the piezoelectric injector in the bidirectional current path;
• and
• switching circuitry for controlling current flow through the piezoelectric fuel injector and the inductor to open and close the piezoelectric fuel injector to inject fuel into an engine, wherein the switching circuitry is controlled to provide a recirculation current to recover energy stored in the piezoelectric injector for storage in the energy storage device.

A drive circuit for a piezoelectric injector, said drive circuit comprising:

• a voltage input for receiving a voltage signal;
• a first energy storage device coupled to the voltage input for storing an electrical charge;
• a second energy storage device coupled to the voltage input for storing an electrical charge;
• a bidirectional current path coupled to a piezoelectric injector;
• an inductor coupled in series with the piezoelectric injector in the bidirectional current path;
• and
• switching circuitry for controlling current flow through the piezoelectric injector and the inductor to open and close the piezoelectric injector, wherein the switching circuitry comprises a first switch that is controlled to charge the piezoelectric injector and a second switch that is controlled to discharge the piezoelectric injector, wherein the switching circuitry is controlled to provide a recirculation current to recover energy stored in the piezoelectric injector in at least one of the first and second energy storage devices.