A positive linear displacement flow rate meter includes a first chamber for receiving a substance such as diesel from a fuel injector and applying a substance force to one end of a piston, wherein an opposing force is applied, such as by air pressure, in a second chamber, to the other piston end, and a comparator, for indicating to a control unit to discard invalid piston displacement measurements, until the substance force is substantially equal to the opposing force, allowing accurate flow rate measurement independent of variation in conditions between uses of the meter.

A positive linear displacement flow rate meter includes a first chamber for receiving a substance such as diesel from a fuel injector and applying a substance force to one end of a piston, wherein an opposing force is applied, such as by air pressure, in a second chamber, to the other piston end, and a comparator, for indicating to a control unit to discard invalid piston displacement measurements, until the substance force is substantially equal to the opposing force, allowing accurate flow rate measurement independent of variation in conditions between uses of the meter.

A flow meter prover with a piston assembly that is movable from a start position to a finish position and an actuator assembly with a carriage that moves between a first position and a second position. Preferably, the carriage is operable to releasably couple to the piston assembly, and the carriage is operable to move the piston assembly from the finish position to the start position as the carriage moves from the second position to the first position. The actuator assembly preferably includes a linear actuator that moves the carriage, and the carriage preferably includes an electromagnet that releasably couples to the piston assembly. The piston assembly preferably slides on a flag rod having first and second flags mounted thereon and two guide rods. A photoelectric sensor senses the flags as the piston assembly slides on the flag rod and generates signals when it senses the flags.

A flow meter prover with a piston assembly that is movable from a start position to a finish position and an actuator assembly with a carriage that moves between a first position and a second position. Preferably, the carriage is operable to releasably couple to the piston assembly, and the carriage is operable to move the piston assembly from the finish position to the start position as the carriage moves from the second position to the first position. The actuator assembly preferably includes a linear actuator that moves the carriage, and the carriage preferably includes an electromagnet that releasably couples to the piston assembly. The piston assembly preferably slides on a flag rod having first and second flags mounted thereon and two guide rods. A photoelectric sensor senses the flags as the piston assembly slides on the flag rod and generates signals when it senses the flags.

A flow totalizer apparatus for totalizing the volume of fluid flowing through the inventive apparatus. The apparatus includes a cylinder having a first cylinder port at one end and a second cylinder port at an opposite end, a piston slidably mounted within the cylinder, a bistable spring mechanism, a directional control valve and a counter. The bistable spring mechanism has a motion axis with two stable positions therealong and includes a drive pin, a piston slotted bar and a spool slotted bar, both slotted bars slidably connected to the drive pin and aligned with the motion axis. The total volume is estimated by cylinder volume times the number of stable-position changes of the bistable spring mechanism.

A flow totalizer apparatus for totalizing the volume of fluid flowing through the inventive apparatus. The apparatus includes a cylinder having a first cylinder port at one end and a second cylinder port at an opposite end, a piston slidably mounted within the cylinder, a bistable spring mechanism, a directional control valve and a counter. The bistable spring mechanism has a motion axis with two stable positions therealong and includes a drive pin, a piston slotted bar and a spool slotted bar, both slotted bars slidably connected to the drive pin and aligned with the motion axis. The total volume is estimated by cylinder volume times the number of stable-position changes of the bistable spring mechanism.

A fluid flow meter comprising a fluid pump to displace fluid with pumping strokes of one or more pumping stroke types wherein each of the one or more stroke types displaces a known volume of fluid, a sensor functionally associated with a fluid reservoir and adapted to generate a signal indicative of a fluid pumping condition within the fluid reservoir, which fluid reservoir is integral or functionally associated with the pump, and circuitry to trigger one or a sequence of strokes of the pump in response to a signal from the sensor.

A fluid flow meter comprising a fluid pump to displace fluid with pumping strokes of one or more pumping stroke types wherein each of the one or more stroke types displaces a known volume of fluid, a sensor functionally associated with a fluid reservoir and adapted to generate a signal indicative of a fluid pumping condition within the fluid reservoir, which fluid reservoir is integral or functionally associated with the pump, and circuitry to trigger one or a sequence of strokes of the pump in response to a signal from the sensor.

A small volume prover apparatus and method for precisely measuring the displaced volume of a fluid. A precision bore cylinder and a piston can be configured with a valve arrangement in order to permit fluid to pass through an annular passage when the piston travels from one position to an opposite position. A magnetized forcer connected to the piston and a magnetic drive chamber configured to produce linear motion of said magnetized forcer are operably connected to the piston in order to move the piston from one position to the other.

A flow totalizer apparatus for totalizing the volume of fluid flowing through the inventive apparatus. The apparatus includes a cylinder having a first cylinder port at one end and a second cylinder port at an opposite end, a piston slidably mounted within the cylinder, a bistable spring mechanism, a directional control valve and a counter. The bistable spring mechanism has a motion axis with two stable positions therealong and includes a drive pin, a piston slotted bar a spool slotted bar, both slotted bars slidably connected to the drive pin and aligned with the motion axis. The total volume is estimated by cylinder volume times the number of stable-position changes of the bistable spring mechanism.