Thermal flow meter with temperature detection element positioned on protrusion of circuit package

Patent metadata

Field	Value
Publication number	US-9810560-B2
Application number	US-201314407663-A
Country	US
Kind code	B2
Filing date	May 15, 2013
Priority date	Jun 15, 2012
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

In order to provide a thermal flow meter for improving workability of a flow rate measurement device having a temperature measurement function for the measurement target gas and measurement accuracy for measuring a temperature, the thermal flow meter is structured such that a flow rate measurement circuit package having a protrusion for measuring a gas temperature is formed through resin molding. An inlet port opened to the upstream side of the measurement target gas is formed, a protrusion is arranged inside the inlet port, an inlet port and an outlet port are formed in the front and rear covers along the protrusion, and the measurement target gas received from the inlet port flows along the protrusion. Since the measurement target gas subjected to the measurement flows along the protrusion, it is possible to reduce influence of the heat from other heat resources and improve measurement accuracy.

First claim

The invention claimed is:

1. A thermal flow meter comprising:
a bypass passage for receiving and flowing a part of a measurement target gas flowing through a main passage,
a circuit package that measures a flow rate by performing heat transfer with the measurement target gas flowing through the bypass passage and measuring temperature of the measurement target gas with at least one temperature detecting resistor,
a housing that holds the circuit package,
a temperature detection element for detecting a temperature of the measurement target gas flowing through the main passage, and
covers that cover the housing,
wherein the circuit package has a protrusion provided with the temperature detection element for detecting the temperature of the measurement target gas,
the covers that cover the housing are arranged on opposite sides of the protrusion forming an inlet port at a leading end of the protrusion for receiving the measurement target gas, and
at least one of the covers is provided with an opening for discharging, to the main passage, the measurement target gas that is received from the inlet port and flows along the protrusion.

2. The thermal flow meter according to claim 1 , wherein
the covers that cover the housing are provided at both sides of the housing, and
the covers are provided with an opening for discharging the measurement target gas to the main passage.

3. The thermal flow meter according to claim 1 , wherein
at least one of the covers that cover the housing is provided with a projection in a vicinity of the inlet port.

4. A thermal flow meter comprising:
a bypass passage for receiving and flowing a part of a measurement target gas flowing through a main passage,
a circuit package that measures a flow rate by performing heat transfer with the measurement target gas flowing through the bypass passage and measures a temperature of the measurement target gas flowing through the main passage,
a housing that holds the circuit package, and
covers that cover the housing, wherein
the circuit package has a protrusion having a temperature detection element for detecting a temperature of the measurement target gas,
the covers that cover the housing are arranged on opposite sides of the protrusion forming an inlet port at a leading end of the protrusion for receiving the measurement target gas,
at least one of the covers is provided with an opening for discharging, to the main passage, the measurement target gas that is received from the inlet port and flows along the protrusion,
the circuit package that measures the flow rate has a circuit package body, and the protrusion that has the temperature detection element protrudes from the circuit package body,
the circuit package body is held inside the housing, and
the protrusion protrudes from the housing toward an upstream direction of the main passage.

5. The thermal flow meter according to claim 4 , wherein
the measurement target gas received from the inlet port flows along the protrusion,
a frontside and a backside of the housing are covered by the covers,
each of the covers is provided with a protecting portion in a portion where the inlet port is formed, and
each of the covers is provided with an opening for discharging the measurement target gas to the main passage in a position in a downstream from the protecting portion in a flow direction of the measurement target gas flowing along the protrusion.

6. The thermal flow meter according to claim 4 , wherein
the measurement target gas received from the inlet port flows along the protrusion,
the covers arranged on opposite sides of the protrusion are provided with a plurality of openings formed along the protrusion, and
the measurement target gas received from the inlet port is discharged from the plurality of openings to the main passage.

7. The thermal flow meter according to claim 4 , wherein
the housing has a hollow opened in an upstream side of the main passage,
the protrusion is provided inside the hollow of the housing,
a flow path for flowing the measurement target gas and the inlet port are formed by covering side surfaces of the hollow with the covers,
the hollow of the housing has an inner surface on one side and an inner surface on the other side by interposing the protrusion, and
at least one of the inner surface on the one side and the inner surface on the other side is shaped to approach the opposite inner surface toward the inside of the hollow.

8. The thermal flow meter according to claim 7 , wherein
the housing has the bypass passage in a center side of the main passage relative to the protrusion,
the hollow approaching the opposite inner surface has a curved shape,
a bypass passage trench for forming the bypass passage is formed along the curved shape, and
the bypass passage is formed by covering the bypass passage trench with the covers.

9. The thermal flow meter according to claim 7 , wherein
the housing has a flange in a wall surface side of the main passage and the bypass passage formed in a center side of the main passage,
a notch portion is provided in the housing in a portion of a flange side of the protrusion, and
a protrusion side surface of the notch portion is one of the inner surfaces of the hollow.

10. The thermal flow meter according to claim 7 , wherein
a projecting portion protruding from the inner surface toward the protrusion is provided at least at one of the inner surface of one side or the inner surface of the other side of the hollow, and
a cross section of the flow path of the measurement target gas for measuring a temperature is narrowed by the projecting portion.

11. The thermal flow meter according to claim 7 , wherein
the protrusion protrudes from the hollow of the housing to upstream of the main passage, and
the inner surface at the flange side of the hollow is shaped to gradually approach the opposite inner surface of the bypass passage side toward the inside of the hollow.

12. A thermal flow meter comprising:
a bypass passage for receiving and flowing a part of a measurement target gas flowing through a main passage,
a circuit package that measures a flow rate by performing heat transfer with the measurement target gas flowing through the bypass passage and measures a temperature of the measurement target gas flowing through the main passage,
a housing that holds the circuit package, and
covers that cover the housing, wherein
the circuit package has a protrusion having a temperature detection element for detecting a temperature of the measurement target gas,
the covers that cover the housing are arranged on opposite sides of the protrusion forming an inlet port at a leading end of the protrusion for receiving the measurement target gas,
at least one of the covers is provided with an opening for discharging, to the main passage, the measurement target gas that is received from the inlet port and flows along the protrusion,
the housing has an external terminal for connection with external devices, a first housing portion in an external terminal side, and a second housing portion in a bypass passage side,
a temperature measurement flow path for flowing the measurement target gas that detects a temperature is arranged between the first and second housing portions,
the inlet port for receiving the measurement target gas is formed in an upstream side in the main passage of the temperature measurement flow path, and
the protrusion is arranged in the temperature measurement flow path.

13. The thermal flow meter according to claim 12 , wherein
a projection protruding to the protrusion is provided at least at one of the inner su

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Tokuyasu Noboru
• Hanzawa Keiji
• Morino Takeshi
• Doi Ryosuke
• Uenodan Akira
• Tashiro Shinobu

Classifications

• G01F5/00

  Measuring a proportion of the volume flow · CPC title

• G01F1/69 Primary

  of resistive type · CPC title

• G01F1/6845

  Micromachined devices · CPC title

• G01F1/6842 Primary

  with means for influencing the fluid flow · CPC title

• G01F15/14

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