Thermal flow meter including fixation wall and concave recess portion for storing end of supporting body

Patent metadata

Field	Value
Publication number	US-9605986-B2
Application number	US-201314406826-A
Country	US
Kind code	B2
Filing date	May 29, 2013
Priority date	Jun 15, 2012
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

The present invention is to improve measurement accuracy of a thermal flow meter. In a thermal flow meter of the invention, a circuit package 400 includes a processing unit 604 in which a passage 605 and a circuit are disposed. An air flow sensing portion 602 is disposed in the passage 605 . A fixing portion 372 is integrally formed with and fixed to the circuit package 400 and forms a bypass passage. The passage 605 of the circuit package 400 is arranged inside the bypass passage. In the bypass passage, a storage portion 384 having a concave portion 383 is formed to face the fixing portion 372 . At least a part of the leading end 401 of the circuit package 400 is contained in the concave portion 383 of the storage portion 384.

First claim

The invention claimed is:

1. A thermal flow meter comprising:
a bypass passage through which a measurement target gas received from a main passage flows;
an air flow sensing portion which measures a heat amount by performing heat transfer through a heat transfer surface with the measurement target gas flowing through the bypass passage; and
a supporting body comprising a first resin material which is integrally formed with the air flow sensing portion such that at least the heat transfer surface is exposed, wherein
the supporting body provides a flow path in which the air flow sensing portion is disposed and a processing unit on which a circuit is disposed,
the supporting body is fixed to a fixation wall which is integrally formed with the supporting body by a second resin material and forms the bypass passage, and the flow path provided by the supporting body is arranged inside the bypass passage, and
a storage portion having a concave portion is formed in the bypass passage to face the fixation wall and made of a third resin material different from the first and second resin materials, and at least a part of an end portion separated from the fixation wall in the flow path provided by the supporting body is contained in the concave portion of the storage portion.

2. The thermal flow meter according to claim 1 , wherein a gap is provided between the portion contained in the concave portion of the end portion separated from the fixation wall and the concave portion.

3. The thermal flow meter according to claim 1 , wherein at least a corner of the end portion separated from the fixation wall is contained in the concave portion of the storage portion.

4. The thermal flow meter according to claim 1 , wherein a protrusion is formed in the storage portion to protrude toward the heat transfer surface of the air flow sensing portion.

5. The thermal flow meter according to claim 4 , wherein the protrusion is extended in a flow direction of the measurement target gas from an upstream side of the heat transfer surface of the air flow sensing portion to a downstream side of the heat transfer surface of the air flow sensing portion.

6. The thermal flow meter according to claim 2 , wherein an abutment portion is formed in the concave portion of the storage portion to abut on the portion contained in the concave portion of the end portion separated from the fixation wall.

7. The thermal flow meter according to claim 6 , wherein the abutment portion abuts on at least any one of a front surface on a side near a measurement surface through which the heat transfer surface of the air flow sensing portion of the supporting body is exposed and a backside of measurement surface on a side opposite to the measurement surface of the supporting body.

8. The thermal flow meter according to claim 2 , wherein a buffer material is disposed between the portion contained in the concave portion of the end portion separated from the fixation wall and the concave portion.

9. The thermal flow meter according to claim 1 , wherein the storage portion includes a plurality of members.

10. The thermal flow meter according to claim 9 , wherein the plurality of members face the backside of measurement surface on a side opposite to the measurement surface through which the heat transfer surface of the air flow sensing portion of the supporting body is exposed.

11. The thermal flow meter according to claim 9 , wherein a gap is provided between the plurality of members.

12. The thermal flow meter according to claim 1 , wherein the storage portion is disposed to be separated from an inside wall of the bypass passage which faces the fixation wall.

13. The thermal flow meter according to claim 12 , wherein the storage portion is formed in a cover member to make the bypass passage on a side near the measurement surface exposing the heat transfer surface of the air flow sensing portion of the supporting body between the fixation wall and an end portion of the inside wall, and on a side near the backside of measurement surface opposite to the measurement surface between the fixation wall and the end portion of the inside wall.

14. The thermal flow meter according to claim 13 , wherein
the cover member includes a front cover which connects the end portions on a side near the measurement surface exposing the heat transfer surface of the air flow sensing portion of the supporting body between the fixation wall and an end portion of the inside wall, and a rear cover which connects end portions on a side near the backside of measurement surface opposite to the measurement surface between the fixation wall and the end portion of the inside wall,
the storage portion includes a front cover protrusion and a rear cover protrusion to protrude from the front cover and the rear cover toward the bypass passage, and
the front cover protrusion and the rear cover protrusion are respectively formed on the front cover and the rear cover.

15. The thermal flow meter according to claim 14 , wherein at least one of the front cover protrusion and the rear cover protrusion includes a hollow which is formed at a corner on a side near the supporting body in the leading end of the protrusion protruding toward the bypass passage, and the concave portion of the storage portion is formed by making end surfaces of the leading ends of the front cover protrusion and the rear cover protrusion face each other.

16. The thermal flow meter according to claim 15 , wherein the hollow is formed at a corner on a side near the supporting body in the leading end of the front cover protrusion.

17. The thermal flow meter according to claim 15 , wherein
the front cover is bonded to end portions on a side near the measurement surface exposing the heat transfer surface of the air flow sensing portion of the supporting body between the fixation wall integrally formed with the supporting body and an end portion of the inside wall of the bypass passage,
the rear cover is bonded to end portions on a side near the backside of measurement surface opposite to the measurement surface between the fixation wall and the end portion of the inside wall, and
when end surfaces of the leading ends of the front cover protrusion and the rear cover protrusion are made to face each other, at least a part of the end portion separated from the fixation wall in the passage of the supporting body integrally formed with the fixation wall is contained in the concave portion of the storage portion which includes the front cover protrusion and the rear cover protrusion.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Morino Takeshi
• Tashiro Shinobu
• Tokuyasu Noboru
• Hanzawa Keiji
• Inoue Atsushi
• Uenodan Akira

Classifications

• G01F1/6965

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

• G01F1/68

  by using thermal effects · CPC title

• G01F1/684

  Structural arrangements; Mounting of elements, e.g. in relation to fluid flow · CPC title

• G01F1/6845

  Micromachined devices · CPC title

• G01F15/14

  Casings, e.g. of special material · CPC title