JPH0422269Y2 - - Google Patents

Description

[Detailed explanation of the idea] Technical field The present invention relates to a heat-sensitive resistance type flow rate detection device.

Prior Art A hot wire flowmeter using an ultra-fine platinum wire has been known as a heat-sensitive resistance flow rate detection device. or,
Flow rate detectors using thin film resistors instead of platinum wires are disclosed in, for example, Japanese Patent Laid-Open No. 57-92211 and Japanese Patent Laid-open No. 57-93212.
It is known from the publication no. Furthermore, a technique for depositing a thin film resistor on a silicon substrate has recently been developed, which has significantly improved the accuracy of fluid flow rate detection.
A flow sensor thus formed from a silicon-based chip must be attached to the fluid flow tube by a support. Furthermore, in order to further improve the accuracy of flow rate detection by such a flow rate detector, the detector chip must be placed in the most stable flow of fluid. Since such a detector chip is relatively small, when it is attached to a relatively large diameter flow pipe, the support itself must not disturb the flow of fluid.

Purpose of the invention The purpose of the present invention is to provide a flow rate detection device in which a chipped flow rate detector as described above can be easily attached to a relatively large-diameter flow pipe and can perform highly accurate flow rate detection. There is a particular thing.

Structure of the invention In the present invention, a part of the fluid flow pipe is formed into a honeycomb shape having a plurality of flow channels by partition walls, and at least one of these flow channels is provided with a thin film-like heat generating layer. The present invention is characterized in that a flow rate detector is disposed in which a heat-sensitive resistor and a heat-sensitive resistor that senses heat from the heat-generating resistor are attached.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, a detector support tube 3 having a square cross section is attached in the middle of a fluid flow tube 1 with a gasket 2 interposed therebetween. A honeycomb structure 4 is attached within the support tube 3, and a plurality of flow channels 6 are formed by partition walls 5 of the honeycomb structure 4. The flow channels 6 extend parallel to the flow tube 1 with a substantially uniform cross-sectional area and allow the fluid indicated by the arrow F to pass therethrough without providing significant flow resistance. Honeycomb structure 4
A flow rate detector 7 is attached to one of the channels 6, and another flow rate detector 8 is attached to the other channel 6. A wire mesh 9 made of metal such as aluminum is placed before and after the honeycomb structure 4.

FIG. 3 is a plan view of the flow rate detector 7, and FIG. 4 is a sectional view thereof. In FIGS. 3 and 4, the flow rate detector 7 is formed of a chip using a silicon crystal wafer as a base material 10, an insulating film 11 made of silicon dioxide or the like is formed on the upper surface of the silicon base material 10, and a predetermined area is further formed on the upper surface of the insulating film 11. Two resistors 12, 1 in the pattern
3 is deposited in a thin film. If photolithography and etching are used to attach the resistors 12 and 13, accurate resistance values can be set. The resistor 12 intended to be arranged upstream with respect to the flow F is made of nickel chrome, and the downstream resistor 13 is made of nickel. Nickel has a larger temperature coefficient of resistance than nickel chrome, so it is sensitive to changes in resistance when it senses heat. Therefore, the upstream resistor 12 is used as a heat-generating resistor, and a current is passed through it to generate heat, and the temperature of the heat-generating resistor 12 changes in accordance with the flow rate of the fluid flowing through it. The flow rate is detected by sensing the resistance of the resistor 13 and measuring the change in its resistance value. Most of the heat from the heat generating resistor 12 is transferred to the heat sensitive resistor 13 via the silicon base material 10, and the remaining small portion is transferred along with the flow of fluid. This detector 7 has extremely high precision and is suitable for mass production. A gold bonding pad 14 is bonded to each end of each resistor 12,13. The other detector 8 has a resistor 1 similar to the heat-sensitive resistor 13.
5 is attached. This detector 8 is a heating resistor 1
They are preferably arranged so as not to be affected by the heat of the two, and are therefore arranged in separate flow paths 6, as shown in FIGS. 1 and 2. This heat-sensitive resistor 15 senses the temperature of the fluid passing through the flow pipe 1 and compensates for temperature changes in the fluid for the heat-sensitive resistor 13, for which purpose these heat-sensitive resistors 13, 15 are connected to a known bridge circuit. Connected.
Further, the detector chip 7 has a rectangular shape of, for example, 7 mm x 5 mm, and the detector chip 8 is slightly smaller than the chip 7.

In FIGS. 1 and 2, the honeycomb structure 4
The partition walls 5 are made of heat-resistant plastic, and the honeycomb structure 4 is made by laminating and bonding corrugated plastic sheets. Therefore, before joining, conductive leads 16,
17, each resistor 12, 13, 15 of the detector chips 7, 8 can be connected to an external electrical device. Alternatively, a thin lead layer may be attached. Therefore, no matter where the detector chips 7, 8 are placed in the honeycomb structure 4, there is no problem with regard to electrical connection.
The detector chips 7, 8 can be easily fixed to the partition wall 5 with adhesive or the like. The wire mesh 9 serves to shield the detectors 7 and 8 from electrical noise from the outside.

Effects of the invention As explained above, the detector chips 7 and 8 can be easily and reliably installed at the desired position even in a large-diameter flow pipe, and the fluid flowing toward the detector chips is The flow is rectified in the flow path in which the chip is placed, and therefore the flow rate can be detected in a stable flow, making it possible to detect the flow rate with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the flow rate detection device according to the present invention, FIG. 2 is a cross-sectional view taken along the line - of FIG. 1,
3 is a plan view of one of the detectors shown in FIG. 1, FIG. 4 is an enlarged sectional view of FIG. 3, and FIG. 5 is a plan view of the other detector. 1... Distribution pipe, 4... Honeycomb structure, 5...
Partition wall, 6... Channel, 7, 8... Detector, 12...
...Heating resistor, 13...Heat-sensitive resistor.

Claims (1)

[Scope of utility model registration request] A part of the fluid flow pipe is formed into a honeycomb shape having a plurality of flow channels by partition walls, and at least one of the plurality of flow channels is provided with a thin film heat generating resistor and the heat generating resistor. What is claimed is: 1. A flow rate detection device comprising a flow rate detector attached with a heat-sensitive resistor that senses heat from the resistor.