Thermal humidity measuring device

Patent metadata

Field	Value
Publication number	US-11092559-B2
Application number	US-201716315424-A
Country	US
Kind code	B2
Filing date	Jul 4, 2017
Priority date	Aug 26, 2016
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A thermal humidity measuring device includes first and second heating elements, and is capable of obtaining a plurality of measurement values (measured values) by effectively utilizing each of the heating elements, which includes measuring humidity by the first heating element. A thermal humidity measuring device includes a first bridge circuit that includes a first heating element that senses humidity, and a second bridge circuit that includes a second heating element that heats air around the first heating element. In the thermal humidity measuring device, a first output signal is extracted from the first bridge circuit, and the humidity is sensed. A second output signal is extracted from the second bridge circuit, and the second output signal includes information relating to at least any one of pressure, an air flow rate, and air temperature.

First claim

The invention claimed is:

1. A thermal humidity measuring device comprising:
a first bridge circuit that includes a first heating element that senses humidity; and
a second bridge circuit that includes a second heating element that heats air around the first heating element;
wherein a first output signal is extracted from the first bridge circuit, the first output signal associated with a sensed humidity;
wherein the first output signal is obtained by inputting a first voltage signal to an output adjusting circuit, the first voltage signal being determined at a first connecting point between the first heating element and a fixed resistor, and wherein the output adjusting circuit is connected to the first bridge circuit and configured to adjust a variation in a second voltage signal, the second voltage signal being determined at a second connecting point between the first heating element and the fixed resistor; and
wherein a second output signal is extracted from the second bridge circuit, the second output signal including information relating to at least any one of pressure, an air flow rate, and air temperature.

2. The thermal humidity measuring device according to claim 1 , further comprising:
a signal processor that corrects an error included in the first output signal;
a pressure sensor that detects ambient pressure; and
a temperature sensor that detects ambient temperature; and
wherein the signal processor extracts an air flow rate signal from the second output signal by removing a pressure component of the second output signal based on an output of the pressure sensor and removing a temperature component of the second output signal based on an output of the temperature sensor, and corrects the first output signal by using the output of the pressure sensor and the air flow rate signal.

3. The thermal humidity measuring device according to claim 1 , further comprising:
a signal processor that corrects an error included in the first output signal and a temperature sensor that detects ambient temperature;
wherein the signal processor extracts a pressure signal from the second output signal by removing a temperature component of the second output signal based on an output of the temperature sensor, and corrects the first output signal by using the pressure signal; and
wherein the first heating element and the second heating element are disposed in a space in which air flow is lower than air flow outside the space.

4. The thermal humidity measuring device according to claim 1 , further comprising:
a signal processor that corrects an error included in the first output signal and a pressure sensor that detects ambient pressure;
wherein the signal processor extracts a temperature signal from the second output signal by removing a pressure component of the second output signal based on an output of the pressure sensor and corrects the error included in the first output signal by using an output of the pressure sensor; and
wherein the first heating element and the second heating element are disposed in a space in which air flow is lower than air flow outside the space.

5. The thermal humidity measuring device according to claim 1 , wherein the first output signal is obtained from a first output terminal and the second output signal is obtained from a second output terminal.

6. The thermal humidity measuring device according to claim 5 , wherein each of the first output terminal and the second output terminal are connected to a signal processing circuit, wherein the signal processing unit outputs a corrected humidity signal at a third output terminal, and wherein the first output terminal is connected to the output adjusting circuit.

7. The thermal humidity measuring device according to claim 6 , wherein the first heating element is heated to a temperature ranging from 500° C. to 600° C. and the second heating element is heated to a temperature ranging from 250° C. to 350° C.

8. The thermal humidity measuring device according to claim 7 , wherein the first heating element is heated to 500° C. and the second heating element is heated to 300° C.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Ando Ryo
• Onuki Hiroshi
• Nakano Hiroshi
• Hosokawa Takeo
• Hio Masayuki
• Komatsu Shigenobu

Classifications

• G01N25/64

  using electric temperature-responsive elements · CPC title

• G01F1/696

  Circuits therefor, e.g. constant-current flow meters · CPC title

• G01K7/24

  in a specially-adapted circuit, e.g. bridge circuit · CPC title

• G01F1/86

  Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure · CPC title

• G01K7/00

  Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat (giving results other than momentary value of temperature G01K3/00) {; Power supply therefor, e.g. using thermoelectric elements} · CPC title