JPH052026A - Gas rate sensor - Google Patents

Abstract

PURPOSE:To hold the flow rate of a gas in a gas flow passage constant and to detect the deflecting state of the gas flow rate with good accuracy by controlling driving of a pump so that the flow rate of the gas jetting into the flow passage detected by a flow sensor becomes a set flow rate. CONSTITUTION:A gas is jet out from a nozzle hole 3 of a main body 8 of the sensor by driving a micropump 11 thereby to generate the gas flow in a gas flow passage 4. At this time, a gas reservoir chamber 9 is integrally formed with the main body 8 so as to buffer the pulsation of the gas flow resulting from the action of the pump 11 and to obtain a stable gas flow in the main body 8. Moreover, a flow sensor 12 formed of a heat sensitive resistance element is provided in the nozzle hole 3 of the main body 8 to detect the flow rate of the gas. A detecting signal of the flow sensor 12 corresponding to the flow rate of the gas jetted out into the gas flow passage 4 from the nozzle mole 3 is read into a pump driving controlling circuit 15, so that the pump 11 is controlled to make the detected gas flow rate equal to a set flow rate at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection state of a gas flow ejected from a nozzle hole of a sensor body into a gas passage when an angular velocity is applied to the sensor body, which is formed by a heat sensitive resistance element. The present invention relates to a gas rate sensor that detects a change in each resistance value generated in a wire.

[0002]

[Prior art]

In this type of gas rate sensor, since the deflection state of the gas flow when an angular velocity acts on the sensor body is detected as a change in the gas flow rate by a pair of heat wires, the nozzle hole is always provided. Therefore, it is necessary to jet a constant flow rate of gas from the above to generate a stable gas flow in the gas flow path.

Therefore, conventionally, a pump is stably driven at a predetermined cycle by using a drive circuit which is stable against fluctuations in power supply voltage and temperature drift.

However, if such a means is adopted, the flow rate of the gas actually flowing in the gas flow passage of the gas rate sensor cannot be known, and the gas flow from the nozzle hole into the gas flow passage due to some cause. When the flow rate of the ejected gas fluctuates, the fluctuation causes a detection error, which lowers the sensor accuracy.

Further, recently, a gas rate sensor in which a sensor body including a nozzle hole, a gas flow path, and a pair of heat wires provided in the gas flow path is formed by micromachining by an IC manufacturing technique using a semiconductor substrate. Has been developed (see Japanese Patent Application Laid-Open No. 3-29858), but in the case of such a sensor body having a very small size, in particular, the flow rate of the gas ejected from the nozzle hole into the gas passage is very small. Even a large change causes a large detection error.

[0007]

The problem to be solved is that when the flow rate of the gas ejected from the nozzle hole into the gas flow path varies due to the driving of the pump, the variation in the gas flow rate becomes a detection error. Therefore, the accuracy of the sensor is reduced.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a gas rate sensor, and more particularly to a means for detecting the flow rate of gas ejected into a gas flow path by a flow sensor provided in the sensor body, and the detection thereof. A means for driving and controlling the pump is provided so that the flow rate of the generated gas becomes a preset flow rate.

In this case, the sensor body is formed by micromachining processing by IC manufacturing technology using a semiconductor substrate, and the flow sensor is formed in the sensor body by micromachining processing.

[0010]

1 to 4 show a sensor body 8 in a gas rate sensor formed by micromachining using a semiconductor substrate.

Then, when the gas is ejected from the nozzle hole 3 of the sensor body 8 by driving the pump to generate the gas flow in the gas flow path 4, the pulsation of the gas flow caused by the driving of the pump is buffered. The gas reservoir 9 for generating a stable gas flow in the sensor body 8 is formed integrally with the sensor body 8.

The sensor body 8 and the gas reservoir 9 have a half hole 31 for forming the nozzle hole 3, a half groove 41 for forming the gas flow path 4, and the gas reservoir 9 on the nozzle hole 3 side. A half groove 91 for forming the gas inflow hole 10 and a half hole 101 for forming the gas inflow hole 10, respectively. The groove 91 and the half hole 101 are overlapped with each other so that they are in contact with each other, and the both are adhered.

A gas passage 4 is formed in the lower semiconductor substrate 1.
Is formed on the upper surface of the bridge portion 6, and the pair of heat wires 51,
52 is patterned, and the electrode portions 7 are similarly patterned on both sides thereof.

In the case where the sensor body 8 and the gas reservoir chamber 9 are integrally formed in this way, as shown in FIG. 5, the micropump 11 is provided on the gas inlet hole 10 side of the gas reservoir chamber 9. Is connected to the gas reservoir 9 by driving the micropump 11 in an atmosphere of gas such as helium.
The gas is sent into the inside, and the pulsating part of the gas sent by the pump is effectively removed, and then the gas flow is ejected from the nozzle hole 3 in the sensor body 8 into the gas flow path 4.

In this case, according to the present invention, a flow sensor 12 composed of a heat-sensitive resistance element for detecting the gas flow rate is provided in the nozzle hole 3 of the sensor body 8 and ejected from the nozzle hole 3 into the gas flow path 4. The pump drive control circuit 15 reads the detection signal of the flow sensor 12 according to the flow rate of the gas, and the drive control of the micro pump 11 is performed so that the detected gas flow rate is always the specified flow rate. It is characterized by that.

The flow sensor 12 is shown in FIGS.
As shown in FIG. 3, a bridge portion 13 is formed by etching in a portion of the half hole 31 forming the nozzle hole 3 in the lower semiconductor substrate 1, and a heat-sensitive resistance material such as platinum is vapor-deposited on the upper surface of the bridge portion 13. It is patterned by etching it.

Alternatively, without forming the bridge portion 13, a wire such as platinum is used as the half hole 31 for forming the nozzle hole 3.
It may be bonded to the lower semiconductor substrate 1 so as to straddle it.

Electrode portions 14 are similarly patterned on both sides of the flow sensor 12.

Further, as the pump drive control circuit 15,
Specifically, as shown in FIG. 5, when a bias voltage is applied to the flow sensor 12 provided in the nozzle hole 3 portion of the sensor body 8 and the gas flow rate through the nozzle hole 3 changes, A power control in which a sensor signal based on a change in the resistance value of the sensor 12 is read and the detected value of the gas flow rate obtained by amplifying the sensor signal is compared with a preset reference value to make them equal. The control unit 151 that outputs the signal WS and the actual power consumption of the micro pump 11 are detected, and the detected power consumption signal is compared with the power control signal WS sent from the control unit 151. A power detection unit 152 that outputs a frequency control signal FS for driving the pump so that the two become equal, and a pulse signal generation unit that generates a pulse signal at a predetermined frequency according to the frequency control signal FS. 53, the pulse signal waveform shaping is constituted by a waveform shaping section 154 applying a driving pulse to the micro pump 11.

Here, as the micropump 11, one driven by a diaphragm type pulse signal is used.

In the embodiment described above, the flow sensor 12 is provided inside the nozzle hole 3 in order to accurately detect the flow rate of the gas ejected into the gas passage 4.
The flow sensor 12 may be provided near the inlet side or the outlet side of the nozzle hole 3. Alternatively, the flow sensor 12 may be provided on the downstream side in the gas flow path 4, although the detection accuracy is slightly lowered.

[0022]

As described above, in the gas rate sensor according to the present invention, a flow sensor is provided at or near the nozzle hole to actually detect the flow rate of the gas ejected from the nozzle hole into the gas passage. The drive of the pump is controlled so that the detected flow rate of the gas becomes a preset flow rate, and the flow rate of the gas flowing in the gas flow path is always kept constant without fluctuation. It becomes possible to accurately detect the state in which the gas flow is deflected by the angular velocity acting on the sensor body with the pair of heat wires, and in particular, the sensor body is formed by the micromachining process by the IC manufacturing technique using the semiconductor substrate. This is advantageous for a very small gas rate sensor.

[Brief description of drawings]

FIG. 1 is a perspective view of a sensor body integrally provided with a gas storage chamber formed by micromachining by an IC manufacturing technique using a semiconductor substrate.

FIG. 2 is a plan view of a lower semiconductor substrate of the sensor body.

3 is a front sectional view taken along the line AA of FIG.

FIG. 4 is a front sectional view taken along the line BB of FIG.

FIG. 5 is a block diagram showing a simplified configuration of a gas rate sensor according to an embodiment of the present invention.

[Explanation of symbols]

1 Lower semiconductor substrate 2 Upper semiconductor substrate 3 nozzle holes 4 gas flow paths 51 heat wire 52 heat wire 8 sensor body 9 gas storage chamber 11 Micro pump 12 Flow sensor 15 Pump drive control circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Hosoi             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory

Claims (3)

[Claims] 1. A pump is driven to eject gas from a nozzle hole in a sensor main body to generate a gas flow in a gas flow passage, and a state of deflection of the gas flow when an angular velocity acts on the sensor main body, In a gas rate sensor that detects changes in each resistance value generated in a heat wire consisting of a pair of heat-sensitive resistance elements arranged side by side in the gas flow path, jets into the gas flow path by a flow sensor provided in the sensor body. The gas rate sensor is provided with a means for detecting the flow rate of the gas to be discharged, and a means for controlling the drive of the pump so that the detected flow rate of the gas becomes a preset flow rate. 2. A sensor main body including a nozzle hole, a gas flow path, and a heat wire pair provided in the gas flow path is formed by micromachining processing using an IC manufacturing technique using a semiconductor substrate, and the sensor main body is provided with a micro. The gas rate sensor according to the above-mentioned item 1, wherein the flow sensor is formed by machining processing. 3. A flow sensor according to claim 1, wherein the flow sensor is provided at or near the nozzle hole in the sensor body.
A gas rate sensor according to the item.