Injector

A liquid coolant injector for injecting a liquid coolant into a cylinder of a split cycle engine, wherein the liquid coolant has been condensed into a liquid phase via a refrigeration process, the injector comprising:

• a thermally insulating housing;
• a liquid coolant inlet;
• a liquid coolant outlet in fluid communication with the liquid coolant inlet via a liquid coolant flow path wherein the liquid coolant flow path extends through the thermally insulating housing, the thermally insulating housing configured to inhibit vaporisation of the liquid coolant within the liquid coolant flow path;
• a valve closure member, moveable between a first position in which the valve closure member blocks the liquid coolant flow path and a second position in which the liquid coolant may flow from the liquid coolant inlet to the liquid coolant outlet;
• and
• a driver operable to move the valve closure member between the first and second positions in response to a control signal,
• wherein the injector is configured such that the valve closure member acts as a pressure release valve when the liquid coolant vaporises in the liquid coolant flow path between the driver and the liquid coolant outlet.

A controller configured to control the opening of a valve closure member of an injector configured to inject a liquid coolant into a cylinder of an engine, wherein the liquid coolant has been condensed into a liquid phase via a refrigeration process, the controller being configured to:

• receive a signal indicative of a parameter of a driver of the injector;
• in response to receiving the signal indicative of the parameter of the driver, determine a resistance of the driver based on the received signal;
• and
• control a current to the driver, based on the determined resistance, to move the valve closure member between a first position and a second position, wherein controlling the current to the driver comprises:
• determining a voltage to be applied to the driver based on the determined resistance, and applying said voltage to the driver to provide a selected current in the driver to move the valve closure member.