초록 ▼

A method and apparatus (10) for sensing a surface level (24) of fluid (12) in a tank (14) having an electrically conducting pickup tube (20) extending through a wall (16) of the tank (14) and into the fluid (12) includes a time domain reflectometry circuit (40) connected to the tube (20) for generat

A method and apparatus (10) for sensing a surface level (24) of fluid (12) in a tank (14) having an electrically conducting pickup tube (20) extending through a wall (16) of the tank (14) and into the fluid (12) includes a time domain reflectometry circuit (40) connected to the tube (20) for generating an incident pulse (68) that travels down the tube (20) and a portion of which is reflected at the surface (24) as a reflected pulse (70,72) which travels back along the tube (20) and is sensed by the circuit (40). The circuit (40) includes a microprocessor (92) which utilizes the elapsed time between the generation of the incident pulse (68) and the receipt of the reflected pulse to determine the position of the surface (24) relative to a reference point and the amount of the fluid (12) in the tank (14) and indicate the amount of fluid at a display (106). The tube (20) forms a transmission line with one of a plate (48), an outer tube (110) and a return tube (130). A sensor (98) connected to the microprocessor (92) generates information representing parameters of the fluid (12) and the microprocessor (92) communicates over a bus line (94).

대표청구항 ▼

An apparatus for sensing a level of a fluid (12) in a tank (14) comprising: a pulse means (40) for generating a plurality of incident pulses (68) and for sensing a plurality of reflected pulses (70,72), said pulse means (40) including a first pulse generator means (74,76) having an output connected

An apparatus for sensing a level of a fluid (12) in a tank (14) comprising: a pulse means (40) for generating a plurality of incident pulses (68) and for sensing a plurality of reflected pulses (70,72), said pulse means (40) including a first pulse generator means (74,76) having an output connected to an input/output signal means (78) for generating said incident pulses (68), a microprocessor means (92) having a first output connected to an input of said first pulse generator means (74,76) for turning on and off said first pulse generator means (74,75), a gate means (74,82,84,86,88) having a first input connected to said input/output signal means (78) and a second input connected to a second output of said microprocessor means (92) and an output connected to a first input of said microprocessor means (92), and wherein said microprocessor means (92) generates a pulse train at said second output for gating said gate means (74,82,84,86,88) to pass said reflected pulses (70,72) to said first input of said microprocessor means (92) and has a third output for generating a sensing signal; and an electrically conductive pickup tube means (20) having a lower end (22) and being connected to said input/output signal means (78) at a point adjacent an upper end (38) spaced a predetermined distance from said lower end (22), said pickup tube means (20) being adapted for insertion into a tank (14) with said lower end (22) in a first fluid (12) for drawing the first fluid (12) from the tank (14) through said pickup tube means (20) whereby when said pickup tube means (20) is inserted into the tank (14) with said lower end (22) in the first fluid (12) and said pulse means (40) generates said incident pulses (68), each said incident pulse (68) travels from said point along said pickup tube means (20) to a surface (24) of the first fluid (12) at a boundary of a second fluid (26) above the first fluid (12) to generate an associated one of said reflected pulses (70,72) which travels back along said pickup tube means (20) to said point, and said microprocessor means (92) is responsive to said generation of said incident pulses (68) and receipt of said associated reflected pulses (70,72) for determining an elapsed time between said generation and said receipt for generating said sensing signal at said third output in response to said elapsed time, said sensing signal representing an amount of the first fluid (12) in the tank (14).