Method and apparatus for metering a fluid mixture

A fluid metering pump, comprising:

• a first cylinder;
• a first piston reciprocally movable within the first cylinder for drawing a first fluid from a first fluid source and discharging the fluid through a discharge conduit;
• a second cylinder;
• a second piston reciprocally movable within the second cylinder for drawing a second fluid from a second fluid source and discharging the second fluid through the discharge conduit, wherein the second fluid mixes with the first fluid within the discharge conduit to form a batch of fluid mixture with a predetermined fluid ratio;
• a shuttle valve in fluid communication with the first fluid source, the first cylinder, and the discharge conduit, wherein the first shuttle valve moves between an intake position, which communicates the first fluid from the first reservoir to the first cylinder, and a discharge position, which communicates the first fluid from the first cylinder to the discharge conduit;
• a biasing spring operatively connected to the first shuttle valve for biasing the first shuttle valve to the intake position;
• and
• a ratio adjustment device operatively connected between the first piston and the second piston, wherein the ratio adjustment device is capable of selecting the fluid ratio of each batch of the fluid mixture.

A fluid metering pump, comprising:

• a fuel cylinder;
• a fuel piston reciprocally movable within the fuel cylinder for drawing fuel from a fuel source 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 means for selecting the fuel-to-oil ratio of each batch of the fuel-oil mixture operatively connected between the fuel piston and the oil piston.

A method of metering fluids with a fluid metering device having a fuel cylinder, a fuel piston reciprocally movable within the fuel cylinder, an oil cylinder, an oil piston reciprocally movable within the oil cylinder, and a ratio adjustment device operatively connected between the fuel piston and the oil piston, wherein the ratio adjustment device is capable of setting a fuel-to-oil ratio of each batch of fuel-oil mixture, the method comprising the steps of:

• providing an oil reservoir;
• filling an oil reservoir with oil;
• providing a fuel reservoir;
• filling a fuel reservoir with fuel;
• selecting a fuel-oil ratio on the ratio adjustment device;
• providing an oil shuttle valve in fluid communication with the oil reservoir, the oil cylinder, and the discharge conduit;
• moving the oil shuttle valve to an intake position, to provide fluid communication between the oil reservoir and the oil cylinder;
• raising the fuel piston with an intake stroke so that the fuel is drawn from the fuel reservoir to the fuel cylinder and the oil is drawn from the oil reservoir to the oil cylinder;
• moving the oil shuttle valve to a discharge position to provide fluid communication between the oil cylinder and the discharge conduit;
• and
• lowering the fuel piston with a discharge stroke so that the fuel and the oil mix within the discharge conduit into a fuel/oil mixture with a selected fuel-to-oil ratio and discharge through a spout.

The method of metering fluid of 17, wherein the ratio adjustment device comprises:

• guide rods attached to a housing of the fluid metering device;
• a variable length rod pivotally connected between the fuel piston and the housing;
• a rack slidably attached to the guide rods;
• and
• a pin operatively connected between the rack and the variable length rod so that an operator can set the fuel-to-oil ratio.