Semiconductor-type flow rate detecting apparatus

Claim 2

A semiconductor-type apparatus for detecting a fluid flow rate comprising: a casing having a communicated portion arranged in a flow path of the fluid; at least one insulating base provided in said casing and having a cut-out portion formed at the communicated portion of said casing; a first rectangular thin plate semiconductor chip having its long sides sufficiently longer than its short sides and arranged in said cut-out portion supported by said insulating base at both short sides so that the long sides are perpendicular to a direction of fluid flow and both surfaces of said first semiconductor chip are substantially in parallel with the direction of fluid flow and having a first temperature detecting element formed on the surface of said first semiconductor chip having a maximum area so that the surface having said first temperature detecting element is parallel with the direction of fluid flow, and both surfaces of said first semiconductor chip are exposed to the fluid flow; and a second rectangular thin plate semiconductor chip having its long sides sufficiently longer than its short sides, positioned in proximity to said first semiconductor chip and arranged in said cut-out portion supported by said insulating base at both short sides of said second semiconductor chip so that the long sides thereof are perpendicular to the direction of fluid flow and both surfaces of said second semiconductor chip are substantially parallel with the direction of fluid flow and having a heater element and a second temperature detecting element formed on the surface of said second semiconductor chip having a maximum area so that said heater element is formed at substantially the center with respect to the long sides of said second semiconductor chip and so that the surface on which said heater element and said second temperature detecting element are formed is also parallel with the direction of fluid flow, and both surfaces of said second semiconductor chip are exposed to the fluid flow.

Claim 3

A flow rate detecting apparatus according to claim 1 wherein said first temperature detecting elment includes a plurality of diodes connected in series with each other.

Claim 4

A flow rate detecting apparatus according to claim 1 wherein said second temperature detecting element includes a plurality of diodes connected in series with each other.

Claim 5

A flow rate detecting apparatus according to claim 1 wherein said cut-out portion of said insulating base is formed along the direction of flow of fluid.

Claim 6

An apparatus according to claim 4 further comprising a projection formed on said insulating base and projecting from said insulating base to said cut-out portion, said first and second semiconductor chips being provided on said projection.

Claim 7

An apparatus according to claim 5 wherein said projection has a thickness less than that of said insulating base.

Claim 8

An apparatus according to claim 6 wherein said projection has a supporting rib.

Claim 9

An apparatus according to claim 1 further including a socket projected to said flow path and wherein said casing is fixedly inserted into said socket.

Claim 10

A flow rate detecting apparatus according to claim 1 further comprising: control means, coupled to said first and second temperature detecting elements and to said heater, for controlling the amount of heat generated by the heater element so as to maintain constant the difference between the temperature detected by the first temperature detecting element of said first semiconductor chip and the temperature detected by the second temperature detecting element of said second semiconductor chip.

Claim 11

A flow rate detecting apparatus according to claim 9 wherein said controlling means comprise a processing circuit arranged on said insulating base for processing a signal produced from said first and second semiconductor chips.

Claim 12

A flow rate detecting apparatus according to claim 1 wherein said at least one insulating base is disposed in said casing in parallel with the direction of fluid flow.

Claim 13

A flow rate detecting apparatus according to claim 1 wherein said cut-out portion is formed in said insulating base having an opening of said cut-out portion at the upstream side of said insulating base.

Claim 14

A semiconductor-type apparatus for detecting a fluid flow rate comprising: a casing having a passage along the longitudinal axis thereof and disposed in a flow path of the fluid; an insulator base plate provided in the passage of said casing in parallel with a direction of flow of the fluid through the passage, said insulator base plate having a cut-out portion formed therein such that an opening of the cut-out portion is located at the upstream end of said insulator base plate, said insulator base plate including a first pair and a second pair of supports, each pair of supports having the supports protruding respectively from both sides of said cut-out portion towards the longitudinal axis of the passage to oppose to each other so that said first pair and second pair of supports are arranged in proximity to each other and along the direction of flow of the fluid; a first rectangular thin plate semiconductor chip having its long sides sufficiently longer than its short sides and having a first temperature detecting element formed on a surface having a moximum area and attached at its opposite short sides to said first pair of protruding supports so that said first semiconductor chip bridges a gap between the opposed protruding supports and is exposed on both surfaces thereof to the fluid flow and that the long sides of said first semiconductor chip are perpendicular to the direction of fluid flow and the surface on which said first temperature detecting element is formed is parallel with the direction of fluid flow; and a second rectangular thin plate semiconductor chip having its long sides sufficiently longer than its short sides and having a heater element and a second temperature detecting element formed on a surface having a maximum area so that said heater element is formed at substantially the center with respect to the long sides of said second semiconductor chip and attached at its opposite short sides to said second pair of protruding supports to bridge a gap between the opposed protruding supports and is exposed on both surface thereof to the fluid flow and that the long sides of said second semiconductor chip are perpendicular to the direction of fluid flow and the surface on which said heater element and said second temperature detecting element are formed is in parallel with the direction of fluid flow.

Claim 15

A semiconductor-type apparatus for detecting a fluid flow rate comprising: a casing having a passage along the longitudinal axis thereof and disposed in a flow path of the fluid; an insulator base plate provided in the passage of said casing in parallel with a direction of flow of the fluid through the passage, said insulator base plate having a cut-out portion formed therein such that an opening of the cut-out portion is located at the upstream end of said insulator base plate, said insulator base plate including a first pair and a second pair of supports, each pair of supports having the supports protruding respectively from both sides of said cut-out portion towards the longitudinal axis of the passage to oppose to each other so that said first pair and second pair of supports are arranged in proximity to each other and along the direction of flow of the fluid; a first rectangular thin plate semiconductor chip having its long sides sufficiently longer than its short sides and having a first temperature detecting element formed on a surface having a moximum area and attached at its opposite short sides to said first pair of protruding supports so that said first semiconductor chip bridges a gap between the opposed protruding supports and is exposed on both surfaces thereof to the fluid flow and that the long sides of said first semiconductor chip are perpendicular to the direction of fluid flow and the surface on which said first temperature detecting element is formed is parallel with the direction of fluid flow; and a second rectangular thin plate semiconductor chip having its long sides sufficiently longer than its short sides and having a heater element and a second temperature detecting element formed on a surface having a maximum area so that said heater element is formed at substantially the center with respect to the long sides of said second semiconductor chip and attached at its opposite short sides to said second pair of protruding supports to bridge a gap between the opposed protruding supports and is exposed on both surface thereof to the fluid flow and that the long sides of said second semiconductor chip are perpendicular to the direction of fluid flow and the surface on which said heater element and said second temperature detecting element are formed is in parallel with the direction of fluid flow.

Claim 16

A flow rate detecting apparatus according to claim 13, wherein the both sides of the cut-out portion of said insulator base plate are registered with opposing inner surfaces of the passage of said casing so that substantially only the protruding supports of said insulator base plate are disposed within the passage of said casing.

Claim 17

A flow rate detecting apparatus according to claim 13, wherein said second pair of supports constitute only paths for the heat generated in the heater of said second semiconductor chip conducted to said insulator base plate thereby to minimize the heat lost to said insulator base plate and the heat conducted to the fluid from said insulator base plate.