JP3124457B2 - Flowmeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter used for measuring a supply air amount and the like required for optimal combustion control in a household or business gas water heater, oil water heater and the like. .

[0002]

2. Description of the Related Art Conventionally, for example, the amount of air supplied for combustion of a gas water heater or the like is estimated from the number of revolutions of a fan motor or power consumption. Alternatively, a difference in air temperature or the like causes a measurement error, which makes it difficult to accurately measure the air amount.

In order to prevent the generation of CO due to a shortage of the air supply amount, the combustion has been performed in the state of excess air so far.
Realization of O _X and low noise has been difficult.

In addition, there has been proposed a method of measuring a differential pressure generated before and after a burner and before and after an orifice in an air supply duct, and obtaining an air supply amount based on the measurement result.

However, in this method, the pressure difference 10MmA _g about the time of maximum combustion becomes less 2MmA _g is at the minimum combustion, a differential pressure gauge itself can measure this range with the required accuracy is expensive In addition, it was not possible to eliminate measurement error factors due to changes in atmospheric pressure due to changes in weather and altitude, differences in temperature, etc., and eventually had the same defects as the measurement results based on the rotation speed of the fan motor.

On the other hand, a flow meter as shown in FIG. 9 has been proposed in order to solve the defect of the method for measuring the amount of air using such a differential pressure gauge. This is a front plate 21a having holes 27a and 27b of a case 21 provided with a flow sensor inside.
In addition, a partition plate 24 provided with a plurality of dust collecting plates 26 on the upper and lower surfaces connects the cylindrical portion 22 whose inside is partitioned into two chambers in the axial direction and whose front end is closed by a front plate 23,
The cylindrical portion 22 is provided with at least a pair of small holes 25a and 25b for communicating each of the rooms with the outside.

[0007] Further, concave portions 53 and 54 are provided on both sides of the partition plate forming the two chambers, respectively, for preventing dew condensation from flowing to the flow rate sensor section. This flowmeter is used by inserting the cylindrical portion 22 into the air passage of the water heater. The airflow is introduced from the small holes 25a, guided to the flow sensor through the maze formed by the dust collecting plate, and then discharged from the small holes 25b.

[0008]

However, in such a conventional flow meter, the cylindrical portion 22 and the dust collecting plate 2 are not provided.
It is necessary to adhere the joints 6 to each other while maintaining their airtightness at these joints. However, since these joint surfaces are arc-shaped curved surfaces, it is difficult to adhere while maintaining the above airtightness. There was a problem that the efficiency was very poor.

Further, since the inside of the water heater is narrow and there is no space for extending the duct to stabilize the air flow, there has been a problem that the output of the flow meter greatly varies due to the influence of the turbulent air flow.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and can improve an assembly efficiency by simplifying a sealing structure of a gas passage, and can provide a gas passage with high airtightness. The purpose is to obtain a flow meter that can be secured.

Another object of the present invention is to provide a flow meter capable of safely storing a thermal type flow sensor in a highly airtight space.

Still another object of the present invention is to provide a flow meter capable of preventing water droplets from remaining in a gas passage.

[0013]

According to a first aspect of the present invention, there is provided a flowmeter having a plurality of flowmeters arranged on a partition wall facing a first chamber in a case to form a gas passage in which a reduced portion and an enlarged portion are connected. A dust trapping wall, a flat sealing lid that is hermetically bonded to an end face of the dust catching wall and an opening end face of the case, and closes the first chamber; and a case that communicates with the gas passage. A side having the gas inlet and outlet provided, and a gas inlet and outlet provided in the partition so as to communicate with the first chamber and the second chamber, and facing the second chamber; A gas flow passage communicating with the introduction hole and the discharge hole is provided on the partition wall surface, and a thermal flow sensor is provided to face the gas passage.

According to a second aspect of the present invention, in the flow meter, the seal ring for closing the gas passage is formed as a ring-shaped body having an irregular cross section by an elastic material.

According to a third aspect of the present invention, in the flowmeter, both chambers communicate with a partition wall that separates the first chamber upstream chamber to which the gas inlet hole belongs and the first chamber downstream chamber to which the outlet hole belongs. A hole is provided.

[0016]

In the flow meter according to the first aspect of the present invention, the first chamber separated in the case is provided with an adhesive or the like between the end face of the dust trapping wall formed in the first chamber and the open end face of the case. A simple operation of joining the sealing lid to make it possible to seal the gaseous to be measured stably through the inlet and outlet holes provided in the partition for the thermal flow sensor in the second chamber. To increase the accuracy of the measured flow rate.

In the flowmeter according to the second aspect of the present invention, since the seal ring is formed in a ring-like body having an irregular cross section by an elastic material, the circuit board on which the thermal type flow sensor is mounted can be pressed relatively weakly against the elastic material. In this case, a sufficient sealing function can be obtained even when the circuit board is joined by the above-mentioned method, and the circuit board and the thermal flow sensor can be prevented from being damaged when the circuit board is assembled.

In the flow meter according to the third aspect of the present invention, dust or dew water adhering to the upstream side of the first chamber is discharged to the downstream side of the first chamber without entering the flow path in which the thermal type flow sensor is installed. Make it possible.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. 1, 2, and 3 are a partially exploded perspective view, a plan view, and a cross-sectional view, respectively, showing a flow meter according to the present invention. In FIG. The case 1 is provided with an inlet 2 and an outlet 3 for projecting and introducing the gas.

In the center of the case 1, a first
A partition wall 4 that separates the chamber A and the second chamber B is provided integrally, and the partition wall 4 facing the first chamber A is a plan view of the case 1 of FIG. As can be seen, a plurality of dust capturing walls 6 forming a gas passage 5 in which the reduced portion 5a and the enlarged portion 5b are connected are alternately protruded, and one end and the other end of the gas passage 5 have an introduction portion, The introduction section 2 and the derivation section 3 as derivation sections communicate with each other.

Reference numerals 7 and 8 denote gas inlet and outlet holes formed in the partition wall 4 in the middle of the gas passage 5 and communicate with the first chamber A and the second chamber B, respectively. .

The introduction hole 7 receives the gas sent into the gas passage 5 on the first chamber A side through the introduction section 2 to the second passage A.
The introduction hole 8 functions to introduce the gas sent to the second chamber B side to the outlet section 3 again through the gas passage 5 of the first chamber A side. Each of the introduction section 2 and the exit section 3 has a designed inner and outer diameter dimension and length.

Reference numeral 9 denotes a plate-like sealing lid for closing the first chamber A of the case 1, which is provided on the end face a of the case 1 on the side of the first chamber A and the end face b of the dust capturing wall 6 with an adhesive. And airtightly contacted and bonded via a double-sided adhesive tape or by welding.

On the outer surface of the sealing lid 9, as shown in FIG. 2, a sign indicating that the introduction section 2 and the exit section 3 are on the gas introduction side and the gas exit side is printed or engraved. Is displayed in.

On the other hand, as shown in FIG. 5, on the partition 4 on the side facing the second chamber B side, as shown in FIG. The protruding edge 10 is provided on the outer peripheral portion of the protruding edge 10.
A seal ring 11 made of a soft elastic material such as silicon rubber and having an X-shaped cross section as shown in FIGS.

In FIG. 3, reference numeral 12 denotes a circuit board on which a thermal flow sensor 13 is mounted on the center of one surface and a semiconductor chip 14 constituting a sensor output processing circuit and the like are mounted on the other surface. This circuit board 12 is provided with a boss 16 as shown in FIG.
At this time, the upper and lower end lines of the seal ring 11 are compressed with respect to the circuit board 12 and the partition wall 4 by compressing the seal ring 11 as shown by a dotted line in FIG. It adheres while bending. At this time, the thermal type flow sensor 13 faces the protruding edge 10 and is sealed between the circuit board 12 and the partition wall 4 by the seal ring 11.

The space between the protruding edge 10 and the circuit board 12 which is in contact with the protruding edge 10 via a seal ring 11 is
A gas passage 15 for guiding the gas introduced from the introduction hole 7 to the extraction hole 8 is provided, and the thermal type flow sensor 13 faces here.

As an example, the thermal flow sensor 13 has a diaphragm 5 on a silicon substrate 51 as shown in FIG.
2. A micro-flow sensor chip having a structure in which heater elements 53 and 55 and temperature-sensitive resistors 54a and 54b using thin-film resistors are provided, and lower portions thereof are removed by etching or the like.

In FIG. 3, reference numeral 17 denotes a back cover which is fitted to the end face of the case 1 on the side of the second chamber B so as to close the second chamber B accommodating the circuit board 12.

FIG. 7 shows a combustion device using a flow meter having the above-described configuration. This device includes an air supply fan 34 for supplying air to a combustion portion 32 through an air passage 33 in a case 31.
Fuel such as gas is supplied to the combustion section 32 by a fuel injection nozzle 35.
And a fuel supply unit 36 that supplies the fuel through the fuel supply unit 36.

A heat exchange section 39 connected to a water supply pipe 37 and a tapping pipe 38 is disposed above the combustion section 32. Further, a part of the air passage 33 is connected to both ends of a branch pipe 40 as a bypass passage for bypassing the air passing through the air passage 33, and a flow meter F of the present invention is provided in the middle of the branch pipe 40. It is connected.

Reference numeral 41 denotes the number of revolutions of the air supply fan 34 and the fuel supply by the combustion supply unit 36 so that the air-fuel ratio is determined by an external command or an automatic control command based on the measurement data of the flow meter F or the like. It is a control device that controls the quantity.

Next, the operation will be described. The flow meter F of the present invention is provided in the combustion device as described above, and the air supplied by the air supply fan 34 operating under the control of the control device 41 and the air supplied by the fuel supply unit 36 are supplied through the fuel injection noise 35. When the air-fuel mixture burns in the air-fuel mixture combustion section 32, the flow rate of air diverted through the branch pipe 40 bypass-connected to the air passage 33 is detected. It is well known that by detecting the flow rate of the split air, the entire flow rate in the air passage can be detected.

The air flow rate data detected by the flow meter F is input to the control device 41, and the air-fuel ratio control for optimal combustion is performed without being affected by pressure, weather conditions, etc. due to the difference in altitude. .

On the other hand, in the flow meter according to the present invention, the first chamber A and the second chamber B separated from each other in
The sealing lid 9 and the back lid 17 can be easily assembled in a sealed state only by bonding them with an adhesive or the like.

Therefore, in the middle of the passage of the gas whose flow rate is to be measured, the gas inlet 2 and the outlet 3
Is connected, the gas is introduced through the introduction unit 2 into the gas passage 5 where the reduced part and the enlarged part in the first chamber A are connected.

In the gas passage 5, the introduced gas is guided to the outlet 3 side of the end of the gas passage 5 so as to sew between the dust capturing walls 6. When the air passes from the enlarged portion to the reduced portion, the flow velocity increases, and the air impinges on the dust capturing wall 6 with the increased flow velocity. At this time, dust and dirt contained in the gas collide with and are captured by the dust capturing wall 6 according to the principle of so-called inertial dust collection.

On the other hand, the gas inlet hole 7 and the outlet hole 8 as described above are formed in the partition wall 4 in the middle of the gas passage 5 in a direction perpendicular to the flow direction of the gas flowing through the gas passage 5. Therefore, part of the gas flowing through the gas passage 5 passes through the introduction hole 7 and is formed by the ring-shaped protruding edge 10 and the circuit board 12 on the back side (the lower side in FIG. 3) of the partition wall 4. It flows into the enclosed gas passage 15.

At this time, the introduction hole 7 is connected to the gas passage 1.
5, it is possible to effectively prevent water droplets due to dust and dew condensation from entering the gas passage 15 side.

The gas flowing into the gas passage 15 passes over the thermal type flow sensor 13 on the circuit board 12,
The gas reaches the gas passage 5 again through the outlet hole 8, and is further discharged through the outlet 3. And the thermal type flow sensor 1
3 detects the temperature of the gas heated by the hot wire and measures the flow rate (mass flow rate) of the gas passing through the gas passage 15.

Therefore, according to this embodiment, the gas in the gas passage 5 is taken into the gas passage 15 in the small space through the introduction hole 7 having a small cross section, whereby the introduction section 2 and the outlet section 3 are introduced. The flow rate of the gas according to the change in the gas flow rate flowing therebetween can be detected with high sensitivity by the thermal flow sensor 13 in the gas passage 15.

The output of the thermal type flow sensor 13 obtained as described above is processed in a signal processing circuit including the semiconductor chip 14 and output to the outside, for example, for the optimal combustion control of a gas water heater. It can be used as air volume data.

Further, the seal ring 11 is provided as shown in FIG.
As shown in FIG. 6A, the ring-shaped body having an X-shaped cross section is formed of a relatively soft elastic material such as silicon rubber, and the cross-sectional shape is shown in FIGS. 6B and 6C. As described above, it is sufficient if the shape is an irregular shape such as an inverted Y-shape or a U-shape.

For this reason, when the circuit board 12 is pressed against the protruding edge 10 so that the thermal flow sensor 13 mounted on the circuit board 12 fits within the protruding edge 10, it is comparatively required. Even with a small pressing force, the seal ring 11 hermetically presses both the circuit board 12 and the partition 4.

As a result, the thermal type flow sensor 13 accurately detects only the gas flow rate (mass flow rate) passing through the inlet hole 7 and the outlet hole 8.

In the flow meter according to the present invention, a communication hole 62 is provided in a wall 61 separating the upstream chamber and the downstream chamber of the first chamber. First
Condensation in the room on the upstream side of the room flows down along the wall surface as water droplets. As the flow of the air passes through the communication hole 62, the water drops also pass and flow into the downstream side of the first chamber.

In this manner, water droplets and dust adhering to the gas passage 5 and the dust capturing wall 6 in the first chamber upstream chamber can be discharged to the first chamber downstream chamber through the communication hole 62. Since air is blown out from the outlet hole 8 of the first chamber downstream side chamber, there is no possibility that water droplets enter there. Therefore, it is possible to prevent them from entering the gas passage 15 through the introduction hole 7. This can prevent malfunction of the thermal flow sensor 13 due to the attachment of water droplets and the like. In addition, as shown in FIG. 4, when the communication hole 62 is provided at the lowermost part of the upstream / downstream partition wall of the first chamber, the above-described effect is most exerted. In addition, the flow through the communication hole 62 reduces the flow through the flow path 15 in which the thermal flow sensor 13 is installed, but there is no practical problem because the thermal flow sensor has high sensitivity.

[0048]

As described above, according to the first aspect of the present invention, a plurality of gas passages arranged on the partition wall facing the first chamber in the case to form a gas passage in which the reduced portion and the enlarged portion are connected to each other are formed. A dust trapping wall, a flat sealing lid airtightly bonded to an end face of the dust trapping wall and an opening end face of the case to close the first chamber, and provided in the case so as to communicate with the gas passage. And a gas inlet and outlet provided in the partition so as to communicate with the first chamber and the second chamber, and a gas inlet and an outlet provided on the partition facing the second chamber. Since a gas passage communicating with the introduction hole and the outlet hole is provided on the partition wall surface, and a thermal flow sensor is provided to face the gas passage, the sealing structure of the gas passage is simplified. Gas passage with high airtightness while improving assembly efficiency The effect of which can be secured is obtained.

According to the second aspect of the present invention, since the seal ring is formed in a ring shape having an X-shaped, Y-shaped, or U-shaped cross section by an elastic material, the thermal type flow sensor can be provided in a highly airtight space. There is an effect that what can be stored safely can be obtained.

Further, according to the third aspect of the present invention, since the upstream / downstream partition walls of the first chamber are provided with the holes communicating the two chambers, water droplets and the like are formed in the flow path where the thermal type flow sensor is installed. This has the effect of obtaining something that can prevent intrusion.

[Brief description of the drawings]

FIG. 1 is a partially exploded perspective view showing a flow meter according to an embodiment of the present invention.

FIG. 2 is a plan view showing the flow meter in FIG.

FIG. 3 is a front view showing the flow meter in FIG. 1 with a part cut away.

FIG. 4 is a plan view showing the flow meter in FIG. 1 in an open state.

FIG. 5 is a rear view showing the flow meter in FIG. 1 in an open state;

FIG. 6 is an explanatory view showing a sealing action and a cross-sectional shape of the sealing in FIG. 3;

FIG. 7 is a conceptual diagram showing a combustion device having a flow meter according to the present invention.

FIG. 8 is a perspective view showing the thermal flow sensor in FIG.

FIG. 9 is a partially exploded perspective view showing a conventional flow meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case A 1st chamber B 2nd chamber 2 Introducing part 3 Outgoing part 4 Partition wall 5 Gas passage 6 Dust capture wall 7 Introducing hole 8 Outgoing hole 9 Sealing lid 11 Seal ring 12 Circuit board 13 Thermal flow sensor 15 Gas passage a Open end face b End face

Continuation of the front page (72) Inventor Kazuo Seki 1-12-2 Kawana, Fujisawa-shi, Kanagawa Yamatake Honeywell Co., Ltd. Fujisawa Plant (56) References JP-A-5-322624 (JP, A) JP-A-8 -94409 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 1/68-1/699 G01F 15/00

Claims (3)

(57) [Claims] 1. A partition which divides the inside of a case into a first chamber and a second chamber, and which is arranged on a partition face facing the first chamber,
A plurality of dust-capturing walls forming a gas passage connecting the reduced portion and the enlarged portion; and a plate-shaped seal airtightly bonded to an end surface of the dust-capturing wall and an open end surface of the case to close the first chamber. A lid, one end and the other end of the gas passage, respectively, and a gas introduction part and a discharge part provided in the case; and the first partition in the middle of the gas passage.
Gas inlet and outlet holes provided to communicate with the chamber and the second chamber, and a gas passage formed in the partition wall facing the second chamber and communicating with the inlet and outlet holes. And a circuit board having a thermal type flow sensor facing the gas passage. 2. The flow meter according to claim 1, wherein the seal ring for closing the gas passage is formed in a ring-shaped body having an irregular cross section by an elastic material. 3. A partition separating the first chamber upstream chamber to which the gas introduction hole belongs and the first chamber downstream chamber to which the outlet hole belongs, and a hole communicating the chambers is provided. The flow meter according to claim 1.