Fluidic control device

Claim 2

In a fluidic device having a main fluid flow inlet conduit, a pair of main fluid flow outlet conduits for receiving fluid from said inlet conduit, and control means for causing responsive to a control signal the main fluid to flow either in one or the other of said outlet conduits, the improvement comprising: two pairs of thermally responsive electrical circuit elements, each pair associated with one of said outlet conduits and the elements forming a respective pair being disposed in tandem to cause fluid flow in the respective conduit to affect first one of said elements and subsequently the other one to produce an ambient temperature-independent temperature differential between the elements forming a respective pair; electrical circuit means coupled for providing current flow through each pair of elements whereby to heat said elements and causing said elements to exhibit an electrical circuit resistance responsive to the fluid flow condition in the respective conduits, and means coupled to said elements for being responsive to the electrical resistance condition exhibited by said respective pairs of elements.

Claim 3

In a fluidic device as set forth in claim 1, said electrical circuit means including an electrical resistance bridge circuit and means for supplying electric energy to said bridge circuit, and each of said thermally responsive electrical circuit elements being connected in a respective arm of said bridge circuit.

Claim 4

In a fluidic device as set forth in claim 2 and including means for balancing said bridge circuit, and said means coupled to said elements comprising an electrical potential responsive device coupled for being responsive to an imbalanced circuit condition of said bridge circuit.

Claim 5

In a fluidic device as set forth in claim 1, said electrical circuit means including a pair of electrical resistance bridge circuits and means for supplying electrical energy to said bridge circuits, and each of the elements forming a pair being connected in a respective arm of a respective bridge circuit.

Claim 6

In a fluidic device as set forth in claim 4 and including means connected to each bridge circuit for balancing such bridge circuit, and said means coupled to said elements comprising a comparison means coupled to said bridge circuits for being responsive to the difference in electrical potential across the output terminals between said bridge circuit.

Claim 7

A fluidic device comprising: a main fluid flow inlet conduit; a pair of main fluid flow outlet conduits disposed for receiving fluid flow from said inlet conduit; control means disposed for causing responsive to a contrOl signal the main fluid flow from said inlet conduit to flow selectively either in one or the other of said outlet conduits; a pair of thermistors disposed in tandem in each of said outlet conduits and the respective thermistors forming a pair being disposed relative to each other so that a quantity of fluid flowing in the associated conduit first affects the first and then the second thermistor forming the pair, whereby to cause responsive fluid flow an ambient temperature-independent temperature difference between said thermistors forming a pair; electrical circuit means coupled for providing current flow through each pair of thermistors to heat said thermistors and to cause said thermistors to exhibit an electrical circuit resistance responsive to the fluid flow condition in a respective conduit, and further electrical circuit means coupled to said thermistors for being responsive to the electrical resistance exhibited by said respective pairs of thermistors, whereby to discern the presence or absence of fluid flow in the respective outlet conduits.

Claim 8

A fluidic device comprising: a main fluid flow inlet conduit; a pair of main fluid flow outlet conduits disposed for receiving fluid flow from said inlet conduit; control means disposed for causing responsive to a contrOl signal the main fluid flow from said inlet conduit to flow selectively either in one or the other of said outlet conduits; a pair of thermistors disposed in tandem in each of said outlet conduits and the respective thermistors forming a pair being disposed relative to each other so that a quantity of fluid flowing in the associated conduit first affects the first and then the second thermistor forming the pair, whereby to cause responsive fluid flow an ambient temperature-independent temperature difference between said thermistors forming a pair; electrical circuit means coupled for providing current flow through each pair of thermistors to heat said thermistors and to cause said thermistors to exhibit an electrical circuit resistance responsive to the fluid flow condition in a respective conduit, and further electrical circuit means coupled to said thermistors for being responsive to the electrical resistance exhibited by said respective pairs of thermistors, whereby to discern the presence or absence of fluid flow in the respective outlet conduits.