JPH0815296A - Mounting structure for hot-wire wind velocity sensor - Google Patents

Abstract

PURPOSE:To provide a mounting structure for a hot-wire wind velocity sensor, allowing the accurate detection of the velocity or volume of supply gas. CONSTITUTION:A hot-wire wind velocity sensor is provided with reference resistors 3 and 4, a feedback amplifier 8 formed out of an operation amplifier 6 and a transistor 7, and an amplifier 9 respectively mounted at upper positions on the surface of a circuit board 13. Also, a square cutout section 14 is formed at the lower right end of the board 13. In addition, a resistance heat generating body 1 and a temperature correction resistor 2 are arranged in the section 14 in such state as separated from each other in a depthwise direction. Then, the board 13 is mounted with the open end 15 of the section 14 directed to the upstream side of an air supply passage 10, thereby positioning the body 1 and the resistor 2 in parallel along the flow direction of the combustion air running in the passage 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot wire type which outputs a signal according to the blowing amount of the blowing gas from a circuit including a resistance heating element for wind speed detection and a temperature compensating resistor arranged in a flow path of the blowing gas. The present invention relates to a wind speed sensor mounting structure.

[0002]

2. Description of the Related Art As a hot-wire wind speed sensor, for example, FIG.
There is known a constant temperature difference type as shown in FIG. This hot-wire wind velocity sensor has a resistance heating element 1 made of, for example, a platinum wire.
And a bridge circuit 5 including a temperature compensating resistor 2 including a heat-sensitive element having the same temperature coefficient as that of the heating element 1 and a pair of reference resistors 3 and 4 having fixed resistance values. When detecting the wind speed, the resistance heating element 1 and the temperature compensating resistor 2 are used.
Are arranged in the flow path of the blown gas, and the resistance heating element 1 has a smaller resistance value than the temperature compensating resistance 2.

In the hot wire wind speed sensor, power is supplied to the bridge circuit 5 via a feedback amplifier 8 composed of an operational amplifier 6 and a transistor 7, so that the heat generation temperature of the resistance heating element 1 flows through a flow path. A current is caused to flow through the resistance heating element 1 so that the temperature is always higher than the above temperature by a constant temperature, and in this state, the voltage generated at the output point P of the bridge circuit 5 (power supply section to the bridge circuit 5) is resistance-heated. The detection signal indicating the wind speed at the position of the body 1 is output via the amplifier 9. Since the air volume at the position of the resistance heating element 1 is the air velocity multiplied by the cross-sectional area of the flow path, the air volume can be detected by the output level of the amplifier 9.

In such a hot wire type wind velocity sensor, when the wind velocity at the position of the resistance heating element 1 increases, the heating element 1
Is cooled, the power supply current to the bridge circuit 5 is increased by the feedback amplifier 8 in order to raise the heat generation temperature of the heating element 1 by a certain temperature with respect to the temperature of the gas flowing in the flow path. Therefore, the output level of the amplifier 9 increases according to the wind speed, and the wind speed can be detected by the output level of the amplifier 9.

The temperature compensating resistor 2 is a resistance heating element 1.
By using a heat sensitive element having the same temperature coefficient as above, when the temperature of the gas flowing through the flow path changes, the heat generation temperature of the resistance heating element 1 becomes a constant temperature with respect to the temperature of the gas flowing through the flow path as described above. In order to maintain a high temperature, the temperature of the resistance heating element 1 is corrected according to the temperature change of the gas in contact with the temperature compensating resistor 2 to maintain a constant temperature difference between the resistance heating element 1 and the gas. Therefore, if the wind speed is constant, the output level of the wind speed sensor (the output level of the amplifier 9) becomes constant even if the temperature of the gas changes. In this case, it is a precondition that the temperature and the wind speed of the gas contacting the resistance heating element 1 and the temperature compensating resistance 2 are the same.

By the way, FIG. 4 shows a state in which the resistance heating element 1 and the temperature compensating resistance 2 are attached to the ventilation passage 10 from the ventilation fan to the burner in the combustion equipment.
The resistance heating element 1 and the temperature compensating resistor 2 are arranged in a notch 12 formed below the circuit board 11 so as to be separated from each other vertically in the radial direction of the air passage 10.

However, when the resistance heating element 1 and the temperature compensating resistor 2 are arranged so as to be separated from each other in the radial direction of the blower passage 10 as described above, the combustion air flowing through the central portion of the blower passage 10 and the inner peripheral wall portion. Since there is a temperature difference and a wind speed difference between the two, the temperature and wind speed of the air contacting the resistance heating element 1 and the temperature compensating resistor 2 may be different.

More specifically, in the case where the combustion air is introduced into the blower passage 10 through the periphery of the combustion chamber, the temperature of the combustion air becomes higher than the temperature outside the blower passage 10, and therefore the inside of the blower passage 10 is increased. The combustion air flowing through the peripheral wall portion radiates heat through the peripheral wall portion, and has a lower temperature than the combustion air flowing through the central portion.

If the combustion air is taken into the blower passage 10 directly from the outside of the combustion equipment, the temperature of the combustion air is lower than the temperature outside the blower passage 10,
The combustion air flowing through the inner peripheral wall portion of the blower passage 10 receives heat via the peripheral wall portion and becomes higher in temperature than the combustion air flowing through the central portion.

On the other hand, regarding the wind speed, it is generally known that the combustion air flowing through the inner peripheral wall portion is slower than the combustion air flowing through the central portion.

Therefore, in such a case, the installation environments of the resistance heating element 1 and the temperature compensating resistor 2 are different, so that the temperature of the combustion air contacting the temperature compensating resistor 2 is changed as described above. Even if the temperature of the resistance heating element 1 is corrected, there is an inconvenience that an error occurs in the detection accuracy of the wind speed and it becomes impossible to supply the air volume corresponding to the burner combustion amount.

The board surface of the circuit board 11 is the air passage 1.
Since it is arranged so as to straddle 0, the inconvenience that the combustion air flowing in the blower passage 10 collides with the substrate surface and the smooth flow of the combustion air in the blower passage 10 is obstructed. there were.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate such inconvenience, and has a mounting structure of a hot wire type wind speed sensor capable of accurately detecting the wind speed or air volume of blown gas. The purpose is to provide.

[0014]

In order to achieve such an object, the present invention sends the blast gas from a circuit including a resistance heating element for detecting the wind speed and a temperature compensation resistor arranged in the blast gas passage. A structure for mounting a hot-wire wind speed sensor that outputs a signal according to the air volume, wherein the resistance heating element and the temperature compensating resistor are arranged in parallel along the flow direction of the blown gas. It is a thing.

Further, according to the present invention, the resistance heating element and the temperature compensating resistor are provided in a notch formed in a mounting substrate, and the mounting substrate has an opening of the notch on an upstream side of the flow path. It is characterized in that it is arranged toward.

Further, the present invention is characterized in that the mounting board is a circuit board to which the circuit is attached.

Furthermore, the present invention is characterized in that the resistance heating element is arranged downstream of the temperature compensating resistance.

[0018]

According to the present invention, since the resistance heating element and the temperature compensating resistance are arranged in parallel along the flow direction of the blowing gas, the resistance heating element and the temperature compensating resistance have substantially the same temperature. In addition, it is possible to bring the blast gas having substantially the same wind speed into contact with each other.

Further, when the resistance heating element and the temperature compensating resistor are provided in the notch formed in the mounting substrate, and the opening of the notch of the mounting substrate is arranged toward the upstream side of the flow path. Since the substrate surface of the mounting substrate is arranged along the flow direction of the blowing gas, the substrate surface does not obstruct the flow of the blowing gas, and the flow of the blowing gas can be made smooth.

Further, if the resistance heating element and the temperature compensating resistor are provided on the circuit board together with the other circuit components, electric wiring can be largely omitted and the structure of the wind speed sensor can be simplified. .

Further, the blast gas passing through the resistance heating element is warmed by the resistance heating element. In this case, by disposing the resistance heating element on the downstream side of the temperature compensating resistance, it is possible to prevent the blast gas heated by the resistance heating element from contacting the temperature compensating resistance. It becomes possible to arrange.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory cross-sectional view of a mounting structure of a hot-wire wind velocity sensor that is an example of the embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. In the present embodiment, the structure in which the hot-wire wind speed sensor is attached to the air passage 10 from the air blow fan to the burner in the combustion equipment is taken as an example. Further, since the basic circuit configuration of the hot-wire wind speed sensor is the same as that of the conventional one, the same parts are designated by the same reference numerals and the description thereof will be omitted.

The overall structure will be described with reference to FIG. 1 and FIG. And operational amplifier 6 and transistor 7
The feedback amplifier 8 and the amplifier 9, which are configured by using, are attached. A rectangular notch 14 is formed in the lower right edge of the circuit board 13. The notch 1
4, a resistance heating element 1 made of a platinum wire and a temperature compensating resistance 2 made of a platinum wire having a resistance higher than that of the resistance heating element 1 are arranged in parallel in the left-right direction so as to be separated from each other. At the time of arrangement, the resistance heating element 1 is arranged on the left side of the temperature compensating resistor 2. In this way, the resistance heating element 1 and the temperature compensating resistor 2 are arranged together with the other bridge circuit components in the circuit board 13
In this case, complicated electric wiring is omitted and the structure of the hot-wire wind velocity sensor is simplified. Circuit board 13
Is determined by the size of the ventilation passage 10, and in this embodiment, the ventilation passage 10 has a diameter of 50 mm, the circuit board 13 has a width of 20 mm, a thickness of 1 mm, and the notch 14 has a radial length of 25 mm. Has become.

As shown in FIG. 1, the hot-wire wind velocity sensor having such a structure is mounted so that the opening 15 of the notch 14 is directed toward the upstream side of the blow passage 10, that is, the blow fan side, and the resistance heating element 1 and The temperature compensating resistors 2 are arranged in parallel along the flow direction of the combustion air flowing through the blower passage 10. By mounting the opening 15 of the cutout portion 14 of the circuit board 13 toward the upstream side of the blower passage 10 in this manner, the circuit board 13 is arranged so that its plate thickness faces the flow of the combustion air. A smooth flow of the combustion air is ensured, and the combustion air comes into direct contact with the resistance heating element 1 and the temperature compensation resistance 2.

At the time of mounting, the resistance heating element 1 is arranged on the downstream side of the temperature compensating resistance 2, and the set of fixed resistance reference resistors 3 and 4, the feedback amplifier 8 and the amplifier 9 are provided in the air passage 10. It is located outside. Further, the lower end portion of the circuit board 13 is fitted into the groove portion 16 formed in the inner wall portion of the blower passage 10 to improve the mounting strength.

In the hot-wire wind velocity sensor having such a structure, when the wind velocity at the position of the resistance heating element 1 increases, the heating element 1 is cooled, so that the heat generation temperature of the heating element 1 is changed to the combustion air flowing through the blower passage 10. The feed current to the bridge circuit 5 is increased by the feedback amplifier 8 in order to raise the temperature by a constant temperature with respect to the temperature. As a result, the output level of the amplifier 9 increases according to the wind speed, and the amplifier 9
The wind speed is detected by the output level of. When the temperature of the combustion air flowing through the blower passage 10 changes, the temperature compensating resistor 2 changes the temperature of the resistance heating element 1 according to the temperature change of the combustion air contacting the temperature compensating resistor 2. To correct.

At this time, since the resistance heating element 1 and the temperature compensating resistance 2 are arranged in parallel along the flow direction of the combustion air, the resistance heating element 1 and the temperature compensating resistance 2 are arranged in the combustion air. Are placed in the same flow field, and combustion air having substantially the same temperature and substantially the same wind speed comes into contact with each other. Therefore, since the installation conditions of the resistance heating element 1 and the temperature compensating resistance 2 are the same,
When the temperature of the resistance heating element 1 is corrected according to the temperature of the combustion air contacting the temperature compensating resistor 2, accurate wind speed detection is performed and the air flow corresponding to the burner combustion amount can be supplied.

The combustion air passing through the resistance heating element 1 is warmed by the resistance heating element 1. In this case, when the resistance heating element 1 is arranged on the upstream side of the temperature compensating resistance 2, the combustion air warmed by the resistance heating element 1 contacts the temperature compensating resistance 2 and comes into contact with both. Since the temperature difference of the air spreads, it becomes necessary to dispose the two so as to be separated from each other by a predetermined dimension, and the circuit board 13 becomes large. However, in the present embodiment, as described above, the resistance heating element 1 is arranged on the downstream side of the temperature compensating resistance 2 so that the combustion air heated by the resistance heating element 1 does not come into contact with the temperature compensating resistance 2. Therefore, both can be arranged close to each other. Therefore, the circuit board 13 can be downsized, and the sensor can be downsized.

In the above embodiment, the resistance heating element 1 and the temperature compensating resistor 2 are provided in the central portion of the blower passage 10, but they may be provided in the inner peripheral wall portion of the blower passage 10.

[0030]

As is apparent from the above description, according to the present invention, the resistance heating element and the temperature compensating resistor are brought into contact with the blowing gas having substantially the same temperature and substantially the same wind speed. Therefore, when the temperature of the resistance heating element is corrected according to the temperature of the blown gas in contact with the temperature compensating resistor, the wind speed can be accurately detected.

Further, when the resistance heating element and the temperature compensating resistor are provided in the notch formed in the mounting substrate, and the opening of the notch of the mounting substrate is arranged toward the upstream side of the flow path. Since the substrate surface is arranged so as not to interfere with the flow of the blown gas, the flow of the blown gas can be made smooth.

Further, when the mounting substrate is a circuit board, the resistance heating element and the temperature compensating resistor are provided on the circuit board together with other circuit components, whereby electric wiring is largely omitted and the wind velocity sensor is Since the structure can be simplified, the manufacturing cost of the sensor can be reduced.

Further, if the resistance heating element is arranged on the downstream side of the temperature compensating resistance, the resistance heating element and the temperature compensating resistance can be arranged close to each other, so that the circuit board and the like can be made small. The sensor can be miniaturized.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of a mounting structure of a hot-wire wind speed sensor that is an example of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a circuit configuration diagram of a hot-wire wind speed sensor.

FIG. 4 is a perspective view for explaining a conventional attachment structure of a hot-wire wind speed sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Resistance heating element, 2 ... Temperature compensation resistance, 5 ... Bridge circuit, 10 ... Blower passage, 13 ... Circuit board, 14 ... Notch part,
15 ... Opening

Claims (4)

[Claims] 1. A structure for mounting a hot-wire wind velocity sensor, which outputs a signal according to the amount of blown air of a blown gas from a circuit including a resistance heating element for detecting the wind speed and a temperature compensation resistor arranged in a flow path of the blown gas. The hot wire wind velocity sensor mounting structure is characterized in that the resistance heating element and the temperature compensating resistor are arranged in parallel along a flow direction of the blown gas. 2. The resistance heating element and the temperature compensating resistor are provided in a notch formed in a mounting board, and the mounting board is arranged with the opening of the notch facing the upstream side of the flow path. The mounting structure of the hot-wire wind speed sensor according to claim 1, wherein 3. The mounting structure for a hot-wire wind speed sensor according to claim 2, wherein the mounting board is a circuit board to which the circuit is attached. 4. The resistance heating element is arranged downstream of the temperature compensating resistor.
3. The mounting structure for the hot wire wind speed sensor according to any one of 3 above.