Heat-sensitive type flow rate detecting element and holder therefor

A thermosensitive flow rate detecting element comprising:

• a flat substrate having opposed first and second surfaces and end wall surfaces transverse to the first and second surfaces;
• a thin film layer comprising an insulating support film and an insulating protective film on the first surface of the flat substrate;
• a heating resistance section including a thermally sensitive resistor having a pattern and a comparative resistance section including a thermally sensitive resistor having a pattern, the heating resistance section and the comparative resistance section being disposed between the support film and the protective film of the thin film layer;
• a recess which penetrates the flat substrate in a thickness direction and faces the heating resistance section and the comparative resistance section;
• and
• at least two fluid flow passages through which the recess is in fluid communication with one of a surface of the thin film layer facing away from the recess and one of the end wall surfaces of the substrate, a first of the two fluid flow passages being upstream of the comparative resistance section and a second of the fluid flow passages being downstream of the comparative resistance section, wherein
• the thermosensitive flow rate detecting element measures one of flow rate and velocity of the fluid, using the heating resistance section, according to fluid temperature sensed by the comparative resistance section, and
• the first of the fluid flow passages is selected from the group consisting of
• (i) a first hole which penetrates the thin film layer in a thickness direction so the fluid flows across the thin film layer on upper and lower surfaces of the thin film layer,
• (ii) at least one groove in the flat substrate and which communicates between a recess wall surface that faces the comparative resistance section and one of the end wall surfaces of the substrates, on the second surface of the flat substrate, and
• (iii) at least one tubular passage within the flat substrate and which communicates between the recess wall surface facing the comparative resistance section and one of the end wall surfaces of the substrate.

An assembly including an element holder accommodating a thermosensitive flow rate detecting element, wherein the thermosensitive flow rate detecting element comprises:

• a flat substrate including a surface and end walls and having a thin film layer comprising an insulating support film and an insulating protective film laminated on the surface of the flat substrate;
• a heating resistance section including a thermally sensitive resistor having a pattern and a comparative resistance section including a thermally sensitive resistor having a pattern, the heating resistance section and the comparative resistance section being disposed between the support film and the protective film of the thin film layer;
• a recess which penetrates the flat substrate in a thickness direction and faces the comparative resistance section, and
• at least two fluid flow passages through which the recess is in fluid communication with one of a surface of the thin film layer facing away from the recess and one of the end wall surfaces of the substrate, wherein the flow rate detecting element measures one of flow rate and velocity of the fluid, using the heating resistance section, according to fluid temperature sensed by the comparative resistance section;
• and
• the element holder has a cross section with an airfoil shape and at least one gap opening in each of upstream and downstream portions with respect to the comparative resistance section.