Flow rate measuring apparatus

Patent metadata

Field	Value
Publication number	US-9810561-B2
Application number	US-201514870152-A
Country	US
Kind code	B2
Filing date	Sep 30, 2015
Priority date	May 15, 2015
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A flow rate measuring apparatus includes: a flow rate detecting device placed in an intake passage; a detection circuit for outputting an analog signal varying depending on the flow rate; a conversion circuit for converting the analog signal to a digital signal; a temperature detecting device for detecting an ambient temperature; and a correction circuit for primarily correcting the digital signal using a gain and/or an offset (correction coefficient) that can set the temperature coefficient in any appropriate way. The gain and/or the offset vary depending on the temperature coefficient set in any appropriate way and the ambient temperature detected by the temperature detecting device. Also, a plurality of the gains and/or the offsets are set depending on the flow rate, allowing the temperature characteristic error in flow rate measurement to be reduced.

First claim

What is claimed is:

1. A flow rate measuring apparatus that is placed in an intake passage of an internal combustion engine and measures the flow rate of intake air, comprising:
a flow rate detecting device placed in the intake passage;
a detection circuit for outputting an analog signal varying depending on the flow rate detected by the flow rate detecting device;
a conversion circuit for converting the analog signal to a digital signal;
a temperature detecting device for detecting the temperature of intake air; and
a correction circuit for performing a primary correction by giving a correction coefficient having a temperature coefficient to a temperature characteristic correction formula that is a linear function of the digital signal,
wherein the correction coefficient varies depending on the temperature coefficient that is set in any appropriate way and the temperature detected by the temperature detecting device, and
wherein a plurality of the correction coefficients are set depending on the flow rate of intake air by dividing a flow rate region of the intake air into a plurality of flow rate regions and separately setting a correction coefficient among the plurality of correction coefficients for each of the plurality of flow rate regions.

2. The flow rate measuring apparatus according to claim 1 , wherein a plurality of the temperature coefficients are set depending on the temperature detected by the temperature detecting device.

3. The flow rate measuring apparatus according to claim 1 , wherein the correction coefficient is a gain or offset or both.

4. The flow rate measuring apparatus according to claim 1 , wherein the temperature detecting device is a heat-sensitive resistor formed on the flow rate detecting device.

Assignees

• Mitsubishi Electric Corp

Inventors

• Hidaka Shinichiro
• Ariyoshi Yuji
• Kawai Masahiro

Classifications

• F02D2200/0414

  Air temperature · CPC title

• G01F15/022

  using electrical means · CPC title

• F02M35/10386

  for flow rate (air flow meters in air cleaners F02M35/021; circuit arrangements for generating control signals by measuring intake air flow F02D41/18) · CPC title

• G01F1/6965

  comprising means to store calibration data for flow signal calculation or correction · CPC title

• G01F1/6842

  with means for influencing the fluid flow · CPC title