JPH0579143B2 - - Google Patents

Description

Detailed Description of the Invention: a. Field of Industrial Application The present invention relates to a temperature control device for a gas rate sensor, and particularly to a temperature control device for reducing the rise time by controlling the temperature based on the gas temperature in the casing when the power is turned on. , relates to novel improvements for reducing power consumption required for temperature control, etc.

b. Prior Art Various configurations have been adopted as this type of gas rate sensor that has been used in the past, and a typical configuration among them is as shown in FIG. 3.

In the figure, the casing designated by reference numeral 1 is approximately cylindrical as a whole and has both ends open. Each end of the casing 1 is connected to a pump holder 2 and a relay terminal plate 3. The inside of the casing 1 is shut off from the outside.

This pump holder 2 is provided with a diaphragm 4a made of an electrostrictive ceramic disk, and the periphery of the diaphragm 4a is integrally fixed to the pump holder 2, thereby forming an electrostrictive oscillating pump 4. There is.

Further, inside the casing 1, an electrode holder 5 is arranged at a position spaced apart from the diaphragm 4a by a predetermined distance.

That is, a plurality of gas guide holes 5a and 5b are formed in the electrode holder 5, and a plurality of electrodes 6a and 6b are arranged symmetrically with respect to the central axis. A hot wire 7a (actually two wires) is connected between these electrodes 6a and 6b by welding.

Furthermore, a nozzle plate 10 having a nozzle hole 8 and an auxiliary hole 9 is provided in the vicinity of the relay terminal plate 3 in the casing 1, and between the relay terminal plate 3 and the nozzle plate 10, A dust plate 11 is provided at a substantially intermediate position.

A pump chamber 12 is formed between the diaphragm 4a of the electrostrictive vibration pump 4 and the pump holder 2, and the gas sent out by the electrostrictive vibration pump 4 is discharged through the discharge port 4b and The gas is sent to the gas passage 13 via the outlet 4c and gas guide holes 5a and 5b.

A signal processing circuit section 14 consisting of an IC is provided at a position outside the relay terminal plate 3 of the casing 1,
This signal processing circuit section 14 receives power from the outside and is connected to the relay terminal 1 of the relay terminal board 3 for taking out the output signals of the hot wires 7a and 7b to the outside.
5.

Further, the relay terminal 3 is provided with a lead pin 16, and this lead pin 16 is connected to the outer casing 1.
It is connected to an external terminal 18 provided at 7.

Furthermore, a heater wire 19 is wound around the outer peripheral surface of the casing 1 and is kept warm by the heat insulating outer casing 17, and a temperature detection element (not shown) is provided on the outer peripheral surface of the casing 1. It is being

The conventional gas rate sensor is configured as described above, and its operation will be explained below.

First, when the electrostrictive vibration pump (gas pump) 4 is energized, the diaphragm 4a vibrates and the gas in the pump chamber 12 is compressed, and this compressed gas is transferred to the diaphragm 4a.
The gas flows into the gas passage 13 through the discharge ports 4b and 4c of a, and the nozzle plate 10 and the dust plate 11
The water is guided into the space formed between the two, passes through the nozzle hole 8 and the auxiliary port 9, passes through the space 1b in the hollow cylindrical part 1a in the casing 1, and is ejected toward each electrode 6a and 6b. be done.

The aforementioned compressed gas uniformly cools and passes through the hot wires 7a (actually a plurality of wires) welded to each electrode 6a and 6b. In this state, when angular velocity motion is applied to the casing 1 from the outside, the hollow cylindrical portion 1a
Due to the deflection of the gas flow within the inner space 1b, the hot wire 7a is cooled unevenly, and the difference is outputted as a voltage. This output voltage is amplified by the signal processing circuit section 14 and outputted from the external terminal 18 as an angular velocity signal.

As mentioned above, the gas rate sensor is extremely sensitive to temperature because it operates based on the cooling difference of the hot wire, and when the heater wire 19 is energized, By controlling the temperature to an even higher constant temperature,
This prevents the effects of external temperature fluctuations.

Therefore, the temperature inside the casing 1 is detected by the temperature detection element, and controlled by a control circuit (not shown) to maintain the above-mentioned constant temperature.

c Problems to be Solved by the Invention Since the conventional gas rate sensor was configured as described above, it had the following problems.

(1) When performing temperature control, it is generally necessary to raise the temperature to a fairly high constant temperature by heating. Therefore, due to sudden temperature changes, a considerable rise time is required for each component to reach a thermal equilibrium state. However, after the power is turned on, it is necessary to wait until stable angular velocity detection is obtained, and only gas rate sensors with extremely poor startup conditions can be obtained.

(2) Furthermore, since gas rate sensors cannot be ignored by changes in outside air temperature, the range of environments in which they can be used as rate sensors has been limited.

(3) Therefore, in order to address the problem mentioned in Section 2, it is necessary to use components that can withstand high temperatures that are higher than the temperature range used as a rate sensor, which would result in a significant cost increase. was invited.

(4) In order to heat to a certain level, it was necessary to innovate in terms of structure and heat retention. In particular, if heat retention is poor, a temperature gradient will occur in the sensor itself, leading to a decline in performance.

(5) In temperature control, in order to reach a certain high temperature in a short time, a large amount of electric power is required at the beginning of power-on, and the power supply capacity of the system using this gas rate sensor also increases the power consumption of the rate sensor. It is also limited in terms of

The present invention has been made to solve the above-mentioned problems, and in particular, by maintaining the temperature inside the casing at the time the power is turned on, it shortens the start-up time, reduces the power consumption required for temperature control, etc. The object of the present invention is to obtain a temperature control device for a gas rate sensor that can obtain the following properties.

d Means for Solving the Problems A temperature control device for a gas rate sensor according to the present invention includes a gas pump provided in a casing for circulating gas, and an electrode holder provided adjacent to the gas pump. , a gas rate sensor comprising a nozzle plate provided opposite to the electrode holder and having a nozzle, a temperature heating and cooling element provided in the casing, connected to the temperature heating and cooling element and the temperature detection element. and comprising a temperature control circuit section for controlling the temperature heating and cooling element, and at least a sample hold circuit and a comparison circuit provided in the temperature control circuit section,
The gas temperature signal detected by the temperature detection element when the power is turned on is stored as a reference temperature in the sample hold circuit, and the difference between the gas temperature signal and the reference temperature generated over time thereafter is compared with the reference temperature. In this configuration, the temperature of the gas is controlled to the reference temperature via the temperature heating/cooling element obtained by a circuit.

e Effect In the temperature control device for a gas rate sensor according to the present invention, the temperature inside the casing when the power of the gas rate sensor is turned on is detected by the temperature detection element, and the temperature control circuit uses the detected temperature as a reference. The unit controls the action of the temperature heating and cooling element, and the inside of the casing is maintained at the detected temperature.

Therefore, the temperature inside the casing remains the same as before.
The temperature is not controlled by a preset, but the temperature at power-on is used as a reference and the temperature is maintained thereafter, so the rise time of the gas rate sensor can be minimized, and the temperature is maintained even after the power is turned on. Almost simultaneously, the operation of the gas rate sensor can be started up.

Therefore, the power consumption required for startup can be significantly reduced, and a gas rate sensor with low power consumption can be obtained.

f Embodiment Hereinafter, a preferred embodiment of the temperature control device for a gas rate sensor according to the present invention will be described in detail with reference to the drawings.

Components that are the same as those in the conventional example shown in FIG. 3 are given the same reference numerals, and their descriptions will be omitted to avoid duplication.

In FIG. 1, an embodiment according to the present invention that is different from the conventional example shown in FIG. A temperature heating and cooling element 20 is provided.
0 is provided with a heat sink 21 connected thereto.

Furthermore, a vacuum section 1c is formed along the longitudinal direction of the wall of the casing 1, the interior of which is kept in a vacuum state, and the structure has a heat-insulating structure without using an external casing as in the conventional structure. has been done. Further, a temperature detection element 22 made of a thermistor is provided inside the dust plate 11, and this temperature detection element 22 is disposed facing the inside of the gas flow path 13, which is a passage through which gas flows. .

Next, the configuration shown in FIG.
3 is a block diagram showing gas rate sensor 2.
Gas temperature signal of temperature detection element 22 provided in 4
GS is input to a sample and hold circuit 25 and a comparison circuit 26, and the output of this comparison circuit 26 passes through an amplifier 27 to which a triangular wave oscillator 28 is connected.
It is input to the PWM modulation circuit 29.

The output signal of this PWM modulation circuit 29 is input to the temperature heating/cooling element 20 via a switching circuit 30.

The temperature control device for a gas rate sensor according to the present invention is configured as described above, and its operation will be described below.

First, when a power source (not shown) is turned on, the diaphragm 4a vibrates and the gas in the pump chamber 12 is compressed, and this compressed gas is transferred to the discharge port 4b of the diaphragm 4a.
and 4c to the gas flow path 13, passes through the temperature detection element 22, passes through the nozzle hole 8 and the auxiliary port 9, and passes through the space 1b in the hollow cylindrical portion 1a in the casing 1 to each electrode 6a. and ejects toward 6b. Therefore, the circulating supply of gas is started.

On the other hand, at the same time as the power is turned on, the temperature detection element 22 detects the gas temperature inside the casing 1, and the detected gas temperature signal GS is input to the sample hold circuit 25, and the gas temperature signal GS is input to the sample hold circuit 25.
The detected temperature is stored as the reference temperature.

Thereafter, as for the self-heating and the temperature change that occurs over time in the ambient environment temperature, the difference from the reference temperature is detected as a differential voltage by the comparator circuit 26, and then passes through the amplifier circuit 27, the PWM modulation circuit 29, and the switching circuit 30. If the gas temperature is input to the temperature heating/cooling element 20 consisting of a thermo module, and the gas temperature becomes higher than the reference temperature mentioned above, it will have a cooling effect, and conversely, if the gas temperature is lower than the reference temperature, it will not have a heating effect. , is always controlled to be at the reference temperature mentioned above.

As described above, when the inside of the casing 1 is maintained at the reference temperature and gas at a constant temperature is flowing past, when an angular velocity movement is applied to the casing 1 from the outside, the gas flow inside the space 1b is deflected. , the hot wire 7a is cooled unevenly, and the difference is output as a voltage. This output voltage is amplified by the signal processing circuit section 14 and outputted from the external terminal 18 as an angular velocity signal.

Therefore, since the temperature of the gas sealed in the casing 1 is detected when the power is turned on and the gas temperature is controlled based on this detected temperature, the hot wire 7a is placed in the gas under extremely thermally stable conditions. As a result, extremely stable temperature characteristics can be obtained.

Although a thermomodule was used as the temperature heating and cooling element, it goes without saying that the same effects can be obtained when other suitable elements are used.

g Effects of the Invention Since the temperature control device for a gas rate sensor according to the present invention is configured as described above, it is possible to obtain the following various effects.

(1) Since the subsequent gas temperature is controlled based on the gas temperature when the gas rate sensor is powered on, the time required for warming up to stabilize the output signal of the gas rate sensor is greatly reduced. , normal operation can be obtained immediately after the power is turned on.

(2) Therefore, by shortening the rise time, it is possible to significantly reduce the power consumption required for temperature control, and a gas rate sensor with low power consumption can be obtained.

[Brief explanation of drawings]

1 and 2 are for showing a temperature control device for a gas rate sensor according to the present invention.
2 is a sectional view showing the overall configuration, FIG. 2 is a block diagram showing a temperature control circuit section, and FIG. 3 is a sectional view showing a conventional gas rate sensor. 1 is a casing, 1c is a vacuum layer, 4 is an electrostrictive vibration pump (gas pump), 5 is an electrode holder, 8 is a nozzle, 10 is a nozzle plate, 13 is a gas flow path, 20 is a temperature heating/cooling element, 22 is a temperature The detection element 23 is a temperature control circuit section.

Claims (1)

[Claims] 1. A gas pump 4 provided in the casing 1 for circulating gas, an electrode holder 5 provided adjacent to the gas pump 4, and an electrode holder 5 provided opposite the electrode holder 5. , a nozzle plate 10 having a nozzle 8, and a temperature heating/cooling element 2 provided in the casing 1.
0, a temperature detection element 22 provided in the casing 1, and a temperature control circuit section 23 connected to the temperature heating and cooling element 20 and the temperature detection element 22, and for controlling the temperature heating and cooling element 20.
and at least a sample hold circuit 25 and a comparison circuit 26 provided in the temperature control circuit section 23.
The detected temperature of the gas temperature signal GS detected by the temperature detecting element 22 when the power is turned on is stored as a reference temperature in the sample hold circuit 25, and the detected temperature generated as time passes thereafter. and the reference temperature is obtained by the comparison circuit 26 and the temperature of the gas is controlled to the reference temperature via the temperature heating and cooling element 20. Device. 2. The temperature control device for a gas rate sensor according to claim 1, wherein the temperature heating/cooling element 20 comprises a thermomodule provided at an end of the casing 1. 3 The temperature detection element 22 is connected to the casing 1
The temperature control device for a gas rate sensor according to claim 1 or 2, wherein the temperature control device is provided facing the gas flow path 13 in the gas rate sensor. 4. The temperature control device for a gas rate sensor according to any one of claims 1 to 3, wherein the casing 1 has a vacuum layer 1c.