US Patent 7784148 Surface cleaning apparatus with cleaning fluid supply

A surface cleaning apparatus comprises a fluid delivery system including a supply of cleaning fluid and a fluid recovery system for drawing dirty cleaning fluid from the surface to be cleaned. The apparatus can comprise a passageway that passes heated motor cooling air in heat exchange with the cleaning fluid to heat the cleaning fluid. The apparatus can further comprise a mixing manifold that mixes first and second cleaning fluids at different concentrations for different cleaning modes. The apparatus can further comprise a fluid valve having a shape memory alloy actuator.