PHYSICAL QUANTITY DETECTION DEVICE

• US 20180283918A1
• Filed: 08/03/2016
• Published: 10/04/2018
• Est. Priority Date: 09/30/2015
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: MIKI, Takahiro, HOSHIKA, Hiroaki, SAITO, Naoki, YOGO, Takayuki, HOSOKAWA, Takeo
• Granted Patent: US 10,641,630 B2
• Time in Patent Office: Days
• CPC Class Codes: G01F 1/68 by using thermal effects
• CPC Class Codes: G01F 1/684 Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
• CPC Class Codes: G01F 1/6842 with means for influencing the fluid flow
• CPC Class Codes: G01F 15/12 Cleaning arrangements; Filters
• CPC Class Codes: G01F 5/00 Measuring a proportion of the volume flow

Abstract

The purpose is to enhance the measurement stability of a flow rate detection unit in a physical quantity detection device by branching an auxiliary passage in which the flow rate detection unit is disposed into first to third passages and providing the third flow passage at an upstream part of the second flow passage. A physical quantity detection device has a circuit board provided with at least one detection unit for detecting the physical quantity of a gas flowing through a main passage and a circuit unit for computational processing of the physical quantity detected by the detection unit, a housing for accommodating the circuit board, a cover fixed to the housing, and an auxiliary passage formed by both the housing and cover that is configured to branch passages from a first passage to a third passage.

Claims

1. A sensor device for physical quantities comprising:

at least a detection portion configured to detect a physical quantity of a measured gas passing through a main passage and has a detection area of air flow;

a printed circuit board (PWB) having a circuit portion for computing the physical quantity detected by the detection portion;

a housing configured house the printed circuit board;

a cover fixed to the housing; and

a bypass passage formed in cooperation with the housing and the cover,

wherein the detection area of air flow is disposed in the bypass passage,

the bypass passage has a first passage that allows an inlet for receiving the measured gas and an outlet for discharging the measured gas to communicate with each other, a second passage bifurcated from the first passage, and a third passage bifurcated from the second passage.

2. The sensor device for physical quantities according to claim 1, wherein the second passage has a curvature, and the detection area of air flow is disposed in the second passage.

3. The sensor device for physical quantities according to claim 2, wherein the third passage is formed to extend toward an outer wall surface at upstream of the housing and have a terminated end portion having a surface facing an air flow direction.

4. The sensor device for physical quantities according to claim 3, wherein an inlet portion of the third passage is arranged upstream of the second passage flowing to the detection area of air flow.

5. The sensor device for physical quantities according to claim 4, wherein the cover has a drainage hole opened to a side surface of the cover, and the drainage hole is provided in a position communicating with the terminated end portion of the third passage.

6. The sensor device for physical quantities according to claim 5, wherein the drainage hole is positioned in a distance LH from the outer wall surface at upstream of the housing, the distance LH being at least set to be equal to or smaller than a half of a distance LB corresponding to a bypass passage width from the outer wall surface at upstream to the outer wall surface at downstream of the housing.

7. The sensor device for physical quantities according to claim 5, wherein the inlet portion of the third passage is disposed in a low velocity portion of a separated flow generated from a bifurcation area between the first and second passages.

8. The sensor device for physical quantities according to claim 6, wherein a hollow portion having a width larger than a passage width of the inlet portion is provided between the inlet portion and the terminated end portion of the third passage.

9. The sensor device for physical quantities according to claim 5, wherein the housing has an outer wall surface in an upstream side of a main flow of the measured gas with respect to the drainage hole, the outer wall surface has a slope portion for changing a direction of the flow of the measured gas, and the slope portion is sloped at an angle set to change a direction of the flow of the measured gas to be apart from the side surface of the cover.