Fluidic liquid level sensor

Claim 2

The combination according to claim 2 wherein the pressure of said power stream is approximately 10 times the pressure of the fluid stream flowing in said pure fluid switching means and the liquid being sensed is water and the fluid applied to said sensing system is air.

Claim 3

A pure fluid system of the type wherein a condition in a given environment is sensed as a function of the impedance to fluid flow said condition produces in a sensor tube, said system characterized by: pure fluid switching means responsive to pressurized fluid applied thereto for flowing a fluid stream as the exclusive fluid flow through said sensor tube and into said environment whenever the fluid flow impedance produced in said sensor tube by said condition is below a predetermined impedance and for directing said stream away from said sensor tube whenever the fluid flow impedance produces by said condition is at least equal to said predetermined impedance; means for applying fluid to said pure fluid switching means at a pressure which is sufficiently high to produce said fluid stream and sufficiently low that said stream does not significantly affect said condition and said environment; and output means responsive to said stream when directed away from said sensor tube for indicating whether the flow impedance in said sensor tube is below said predetermined impedance; wherein said condition being sensed is the level of a liquid, said sensor tube being disposed to dIrect the fluid stream flowing therethrough from an egress end of said tube toward the surface of the liquid level being sensed, the pressure of the fluid stream flowing through said sensor tube being sufficiently low as not to produce perturbations in the liquid when the liquid level is below the egress end of said tube.

Claim 4

The combination according to claim 4 wherein the fluid comprising said fluid stream is a gas.

Claim 5

The system according to claim 4 wherein is further provided means for blowing high pressure fluid through said sensor tube upon removal thereof from the liquid of which the level is sensed, said high pressure fluid being at a sufficiently high pressure to remove any of said liquid adhering to the interior of said sensor tube.

Claim 6

the system according to claim 6 further comprising means responsive to said output means for preventing addition of further liquid to the liquid being sensed whenever said liquid level achieves the height of the egress orifice of said sensor tube.

Claim 7

A fluid system comprising a liquid level sensor of the type wherein a stream of fluid is issued from an egress orifice of a sensor tube toward the surface of the liquid, the impedance to fluid flow through said sensor tube being varied as a function of the liquid level being sensed, said system being characterized by: pure fluid switching means including an input nozzle for issuing a stream of fluid in response to pressurized fluid applied thereto, a first output passage for receiving said stream of fluid in the absence of a back pressure therein above a predetermined pressure, and a second output passage for receiving said stream of fluid only in response to a back pressure above said predetermined pressure in said first output passage; means for interconnecting said first output passage and said sensor tube such that only fluid issued by said input nozzle and received by said first output passage is directed toward the surface of said liquid; means for applying fluid to said input nozzle at a pressure which is sufficiently high to produce said stream of fluid and sufficiently low as not to produce perturbations in said liquid.

Claim 8

The combination according to claim 8 further comprising a pure fluid logic element comprising: a power nozzle responsive to pressurized fluid applied thereto for issuing a power stream, a control nozzle connected to said second output passage of said pure fluid switching means to receive said stream of fluid therefrom, first output means disposed to receive said power stream only in the absence of said stream of fluid at said control nozzle, and second output means disposed to receive said power stream only in the presence of said stream of fluid at said control nozzle; and means for applying pressurized fluid to said power nozzle at a pressure which is substantially higher than the pressure applied to said pure fluid switching means.

Claim 9

The combination according to claim 9 wherein said pressurized fluid is a gas.

Claim 10

The combination according to a claim 10 wherein the predetermined pressure required to produce flow in said second output passage is achieved only when the egress end of said sensor tube is immersed in the liquid.

Claim 11

The system according to claim 11 further comprising: a second substantially identical liquid level sensor, the sensor tube of said second liquid level sensor having its egress orifice disposed at a higher level than the egress orifice of the sensor tube in the first-mentioned liquid level sensor; a bistable device; means responsive to power stream flow at said second output means of said first-mentioned liquid level sensor for transferring said bistable device to a first stable state; and means responsive to power stream flow at the first output means of said second liquid level sensor for transferring said bistable device to a second stable state.

Claim 12

The system according to claim 12 further comprising means responsive to said first stable state for adding liquid to the liquid being sensed whereby to raise the level thereof.

Claim 13

In a system for sequentially filling containers with fluid material wherein a start signal is provided whenever a filling operation for a container is to be initiated, a control circuit for initiating said filling operation and terminating same when the fluid material in a container being filled reaches a predetermined level, said control circuit comprising: a fluidic liquid level detector comprising: a sensor tube having an upstream end and a downstream end, said downstream end extending to said predetermined level in said container being filled; fluidic switching means comprising the exclusive means for flowing pressurized fluid through said sensor tube from said upstream and to said downstream end whenever the level of fluid material in said container being filled is below said predetermined level and for preventing said pressurized fluid from flowing through said sensor tube whenever the fluid material in said container being filled is at or above said predetermined level, said pressurized fluid being at a sufficiently low pressure as not to produce perturbations in the fluid material in said container being filled; and means responsive to the prevention of pressurized fluid flow through said sensor tube for providing a first signal; circuit means responsive to said start signal for providing a signal pulse; and bistable means for assuming a first stable state in response to said signal pulse and a second stable state in response to said first signal.

Claim 14

The control circuit according to claim 14 wherein said system additionally provides a container-in-place signal, and wherein said circuit means includes means responsive to the provision of said start signal and container-in-place signal in time coincidence for providing said signal pulse.

Claim 15

The control circuit according to claim 14 further comprising means for selectively flowing high pressure fluid through said sensor tube.

Claim 17

The method according to claim 17 wherein step b. includes the step of redirecting pressurized fluid flow through a fluid passage whenever said one end of sensor tube is blocked by said liquid, and wherein step c. includes the step of sensing flow of said pressurized in said fluid passage.