Solid state fluid flow sensor
First Claim
1. A solid state fluid flow sensor for measuring the mass flow of a fluid through a conduit, said sensor comprising:
- a thin film insulative supporting member in the conduit;
a first integrated circuit chip mounted on said member, said first chip having a first diode-connected transistor temperature sensing means integral therewith for monitoring the ambient temperature of the fluid flowing past the first circuit chip and generating an electrical signal proportional to said fluid ambient temperature;
a second integrated circuit chip located adjacent said first chip on said member, said second chip having a second diode-connected transistor temperature sensing means and a transistor heating means integral therewith for heating the second chip, said second temperature sensing means generating a second electrical signal proportional to the temperature to which said second chip is heated;
circuit means connected to said first and second chips supplying an amount of current to said transistor heating means for heating and maintaining said second chip at a predetermined constant temperature difference from said first chip above the ambient fluid temperature in response to the voltage drop across said first and second temperature sensing means; and
indicating means responsive to the amount of current supplied to said transistor heating means to indicate the mass fluid flow through the conduit, said current varying in proportion to changes in the mass fluid flow.
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0 Petitions
Accused Products
Abstract
A fluid flow sensor fabricated by integrated circuit techniques is positioned within fluid flow passages for measuring the mass flow of fluid therethrough. The sensor comprises three solid state circuit devices wherein two are fabricated on a chip separate from the third device.
The first device is responsive to forced convective heat transfer by the fluid flowing thereover for generating a first electrical signal. The third device is responsive to temperature of the fluid thereover for generating a second signal and the second device is responsive to both said first and second electrical signals for maintaining said first device at a predetermined temperature above said third device.
A fuel metering system for internal combustion engines is described utilizing a fluid flow sensor for measuring the mass flow of both fuel and air into the throttle body. Circuit means responsive to said sensors operate to maintain a predetermined fuel-air ratio in said internal combustion means.
68 Citations
7 Claims
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1. A solid state fluid flow sensor for measuring the mass flow of a fluid through a conduit, said sensor comprising:
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a thin film insulative supporting member in the conduit; a first integrated circuit chip mounted on said member, said first chip having a first diode-connected transistor temperature sensing means integral therewith for monitoring the ambient temperature of the fluid flowing past the first circuit chip and generating an electrical signal proportional to said fluid ambient temperature; a second integrated circuit chip located adjacent said first chip on said member, said second chip having a second diode-connected transistor temperature sensing means and a transistor heating means integral therewith for heating the second chip, said second temperature sensing means generating a second electrical signal proportional to the temperature to which said second chip is heated; circuit means connected to said first and second chips supplying an amount of current to said transistor heating means for heating and maintaining said second chip at a predetermined constant temperature difference from said first chip above the ambient fluid temperature in response to the voltage drop across said first and second temperature sensing means; and indicating means responsive to the amount of current supplied to said transistor heating means to indicate the mass fluid flow through the conduit, said current varying in proportion to changes in the mass fluid flow. - View Dependent Claims (2, 3, 4, 5)
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6. A solid state fluid flow sensor apparatus responsive to the mass flow rate of a fluid through a conduit, and comprising:
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a supporting member in the conduit; a first integrated circuit chip mounted on said member and having a first solid state diode-connected transistor thereon connected to a first constant current source for monitoring the ambient temperature of the fluid and generating an electrical signal proportional to said temperature; a second integrated circuit chip located adjacent said first chip on said member and having a second solid state diode-connected transistor thereon connected to a second constant current source, said second chip also having a transistor heating means integrally formed thereon and electrically connected to a voltage source for conduction between its collector and emitter leads to heat said second diode on said second chip, an operational amplifier having its inverting input terminal electrically connected between said first constant current source and said first diode-connected transistor, its noninverting input terminal electrically connected between said second constant current source and said second diode-connected transistor and its output terminal electrically connected to the base of said heater transistor on said second chip, said amplifier responsive to the voltage difference across its input terminals for supplying base current to said heater transistor to heat and maintain said second diode-connected transistor on said second chip at a predetermined temperature difference above said first diode-connected transistor on said first chip; and utilization means responsive to the current flowing through said transistor heating means as a measure of the mass rate of fluid flow through the conduit. - View Dependent Claims (7)
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Specification