Patent ID: 7562792

Claim:
A fluid metering pump, comprising: a fuel cylinder; a fuel piston reciprocally movable within the fuel cylinder for drawing fuel from a fuel reservoir and discharging the fuel through a discharge conduit; an oil cylinder; an oil piston reciprocally movable within the oil cylinder for drawing oil from an oil reservoir and discharging the oil through a discharge conduit, wherein the oil mixes with the fuel within the discharge conduit to form a batch of fuel-oil mixture with a predetermined fuel-to-oil ratio; an oil shuttle valve in fluid communication with the oil reservoir, the oil cylinder, and the discharge conduit, wherein the oil shuttle valve moves between an intake position, which communicates the oil from the oil reservoir to the oil cylinder, and a discharge position, which communicates the oil from the oil cylinder to the discharge conduit; a biasing spring operatively connected to the oil shuttle valve for biasing the oil shuttle valve to the intake position; and a ratio adjustment device operatively connected between the fuel piston and the oil piston, wherein the ratio adjustment device is capable of setting the fuel-to-oil ratio of each batch of the fuel-oil mixture.