JPS63293471A - Gas rate sensor - Google Patents

Abstract

PURPOSE:To shorten a warm-up time after power-on operation and to obtain stable characteristics even when a sensor is left as it is for a long time by providing a couple of hot wires and resistances constituting a bridge circuit in the same enclosed container. CONSTITUTION:In a signal conversion system constituted on a circuit board, the bridge circuit is constituted having the couple of hot wires L and R as each sides and the resistances R1 and R2 as two other sides. When the gas rate sensor constituted as mentioned above is applied with a rate, the hot wires L and R vary in temperature and their variations are converted by the bridge circuit into electric signals. Those electric signals are amplified by an amplification system C to obtain a detection signal corresponding to the rate. Here, the signal conversion system such as the bridge circuit and a rate detection system such as the hot wires are provided in the enclosed container and then the influence of the temperature dependency of each parts in the container is a little, thereby shortening the warm-up time after power-on operation. The stability of an offset voltage to variation in ambient temperature increases and the stable characteristics are obtained even after the sensor is left as it is for a long time.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to a gas sensor that detects the rate by utilizing the change in the heat dissipation state of a pair of hot wires when a rate (angular velocity) is applied to the sensor body. This relates to rate sensors.

[Conventional technology]

FIG. 4 is a sectional view showing the structure of a conventional gas rate sensor of this type (see Japanese Utility Model Application Publication No. 17559/1983).

In the figure, l is a sealed container filled with gas 2 for rate detection such as helium or a mixture thereof, and a heater 3 made of metal resistance wire is wound around the entire outer periphery with an insulating liquid RFT 4 interposed therebetween. It becomes a constant temperature bath at °C. In addition to the gas 2, a pair of heating elements A5 made of thin metal wires are placed in this airtight container l, stretched around a ceramic disc 6, and a heating wire 5 is stretched around the disc 6. Metal pillars are buried at regular intervals, and holes are drilled through which the gas 2 that has passed through the hot wire 5 passes. Also, sealed container 31
Inside, gas 2 is directed in a certain direction! A pump 7 for causing ltQ is also arranged. This pump 7 is made by pasting a piezoelectric element on a metal plate, and has one small hole.When an AC voltage is applied, it vibrates, and the gas 2 flows through the small hole, turning the intake and exhaust gases. 2 circulate in a fixed direction. Reference numeral 8 denotes an aluminum group holder which fixes the ceramic disk 6 and supports the pump chamber cover 9. One end is equipped with a nozzle 10 for rectifying the turbulent gas 2 into a laminar flow, and the other end is attached with a nozzle 10 for rectifying the turbulent gas 2 into a laminar flow. Fixing ring 11 on the side
is in contact with. 12 is an exhaust pipe for the gas 2, 13 is a hermetic base in which a ring-shaped rib is projection welded to the flange of the closed container l, and inlet terminals 14 for, for example, 9 bottles are embedded in the base by hermetic seal processing.
The introduction terminal 14 and the lead terminal 15 of the hot wire 5 are connected to electrically connect the inside and outside of the sensor body.

Further, the exhaust pipe 12 serves as an exhaust and gas filling [1] for replacing the inside of the closed container 1 with gas, and after filling the gas 2, it is sealed by welding, pressure welding, or the like.

FIG. 5 is a block diagram showing the system-specific configuration of the gas rate sensor configured as described above. Inside the sealed container 1, there are a rate detection system A including a gas 2, a hot wire 5, a pump 7, etc., and a signal conversion system B having a bridge circuit that converts the detection signal into an electric signal.
, an amplification system C for the converted signal, and the like are provided. Also, outside the container (is the hot wire power supply system D that drives the heat 1115 above)
, a pump drive system E that drives the pump 7, a heater temperature control system F that controls the temperature of the heater 3 and makes the inside of the container a constant temperature bath, a power supply system G that supplies power to each of the above prefectures, etc. There is.

Next, the operation will be explained. heat)! ij5 is heated by a constant current flowing through it, and is uniformly cooled by a constant laminar flow gas 2 when no rate is applied to the sensor body. When a rate is applied to the sensor body, the Coriolis force causes a bias in the gas 2 in the closed container 1, causing a change in the heat dissipation state of the pair of hot wires 5. This change is heat ray 5
It appears as a temperature change 7, and is further converted into electrical power 13 by a bridge circuit with each hot wire 5 as one side,
Extracted as rate output. Then, the running position of an automobile or the like is detected based on this rate output, and it functions as a direction sensor.

[Problems to be Solved by the Invention] However, in the conventional gas rate sensor, due to the temperature dependence of each component in the closed container 1, the warm-up time until the temperature inside the electric organ becomes stable is high. The time is long;
In addition, the temperature balance of each component changes depending on the ambient temperature, so the offset voltage tends to fluctuate.Furthermore, if left unused for a long time, the electronic components and circuit board absorb moisture, causing changes in impedance, resulting in unstable characteristics. There was a point.

This invention was made after solving these problems. tt#tTo provide a gas rate sensor that has a short warm-up time after two people, has a stable offset voltage for one ambient temperature, and has stable characteristics even after being left for a long time.

(Means for Solving the Problems) The gas rate sensor of the present invention includes a pair of hot wires arranged in a closed container filled with gas, and a resistor that constitutes a bridge circuit with each of the pair of hot wires as one side. and detects the rate by converting a temperature change occurring in the hot wire due to the gas flow into a resistance value change of the resistor when a rate is applied to the sensor body,
The resistor constituting the bridge circuit is provided in the same sealed container as the pair of hot wires.

[Effect]

In the gas rate sensor of the present invention, the pair of hot wires and the resistor constituting the bridge circuit are provided in the same sealed container as the hot wires, so the temperature inside the sealed container quickly stabilizes and is not affected by the influence of ambient temperature. The impedance of each component does not change much even if it is left unused for a long time.

(Embodiment) Fig. 1 is a sectional view showing an embodiment of the present invention, and the same reference numerals as in the conventional Fig. 4 indicate the same components. A container, 2 is a gas sealed in the container, 3 is a heater, 4 is an insulating coating, 5 is a pair of hot wires, 6 is a ceramic disk that supports the hot wires 5, 7 is a pump that circulates the gas 2, 8 is a hot wire 5 and a holder for holding the pump 7, etc., 9 is a pump chamber cover, 10 is a gas 2
11 is a ring for fixing the holder 8, 1
2 is an exhaust pipe, 13 is a hermetic base that seals the inside of the container, 14 is an introduction terminal, and 15 is a lead terminal for the hot wire 5, which is connected to the introduction terminal 14. Reference numeral 16 denotes a circuit board on which resistors R, , R2, etc. constituting a bridge circuit are mounted, with the pair of heat fi5 as one side, and the circuit board is placed in the same atmosphere as the hot wire 5 in the closed container l. 2
It is located in a space that does not disrupt the flow of water.

FIG. 2 is a block diagram 1 showing the configuration of each system, and as shown in the figure, a rate detection system A inside a sealed container 1 (inside the sensor body) includes a signal conversion system B and a part of other systems, for example. Part of the amplification system C is incorporated.

FIG. 3 also shows the signal conversion configured on the circuit board 16;
FIG. 4B is a circuit configuration diagram showing details of 4B. As I said,
A pair of hot wires 5 are connected to one side (R.

As L), a bridge circuit is constituted by resistors R,,R,. Also, resistor R3 for offset voltage adjustment
and a variable resistor VR, and an equivalent resistor R4 and noise removal capacitors C1 and C corresponding to the bridge circuit for canceling out leakage current from the amplification system C.
2 is provided.

In the gas rate sensor configured as described above, when a rate is applied to the sensor body, a temperature change occurs in the hot wire 5 as in the conventional case, and this change is converted into an electrical signal by the bridge circuit shown in Figure 3. Ru. And this electricity 1
No. 3 is amplified and output, and a detection signal can be obtained according to the rate.

Here, since the signal conversion system B such as the bridge circuit described above is provided in the same atmosphere as the rate detection system A, the influence of the temperature dependence of each component in the sealed container 1 is very small. . That is, each component on the circuit board 16 has its own temperature dependence, which causes instability when detecting minute changes as in this embodiment. However, by housing each of these parts in the same atmosphere as rate detection system A, the temperature change of each part can be kept within the range of change under the same conditions, and the above instability factors can be removed. becomes. In this embodiment, each component listed in F is placed in a closed container 1 filled with gas 2 to maintain a balance with the temperature of gas 2. At this time, if the circuit board 16 and the like are formed of a material with relatively good thermal conductivity, and are thermally coupled to the sealed container Bt with a material with good thermal conductivity, it is possible to have the minimum thermal resistance. It has a unique mounting structure. With this structure, the same temperature conditions are satisfied, highly stable characteristics are obtained, and the warm-up time from the power source is minimized, reducing the heating time to approximately be shortened. In addition, the stability of offset voltage and the like against fluctuations in ambient temperature increases, and the characteristics become stable even after being left unused for a long time.

The gas rate sensor of the present invention can be used, for example, as a traveling position detection device in an inertial navigation device for an automobile or a special vehicle, a guidance device for an unmanned carrier L or a self-propelled robot,
It is possible to use it as a direction detection sensor for the motion of a moving or displaced object, an attitude control device, or various measuring instruments.

〔Effect of the invention〕

As explained above, according to the present invention, since the circuit components of the signal conversion system that converts the detection signal from the hot wire into an electric signal are placed in the same sealed container as the hot wire, the warm-up time after power is turned on is shortened. In this way, it is possible to obtain the effect that the offset voltage with respect to the ambient temperature is stabilized and the characteristics are stabilized even after being left for a long time.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of each system, FIG. 3 is a circuit configuration diagram showing details of the signal conversion system in FIG. 2, and FIG. The figure is a sectional view showing the structure of a conventional gas rate sensor, and FIG. 5 is a block diagram showing the structure of each system. 1... Airtight container 2... Gas 5... Hot wire 7---Pump 10---Nozzle 16... Circuit board R+, FL2 --- Resistor Applicant Honul Giken Kogyo Co., Ltd. Stanley Electric Co., Ltd. Fig. 1 1: Sealed container 2: Sword 5: Sword ↑ 7 Ni Plate R1, R24β (Fig. 2, 1, 3, 4, 5)

Claims (3)

[Claims] (1) A pair of hot wires is placed in a sealed container filled with gas, and a resistor is provided that forms a bridge circuit with each of the pair of hot wires as one side, so that when a rate is applied to the sensor body, the gas In a gas rate sensor that detects the rate by converting a temperature change occurring in the hot wire due to the flow into a resistance value change of the resistor, the resistor constituting the bridge circuit is placed in the same sealed container as the pair of hot wires. A gas rate sensor characterized by being provided with. (2) The fixed resistance part of the offset voltage adjustment circuit, which is part of the signal conversion system, and the equivalent resistance corresponding to the bridge circuit for canceling out the leakage current from the amplification system, or both or either one, in the same container. The gas rate sensor according to claim 1, wherein the gas rate sensor is installed in an atmosphere. (3) The gas rate sensor according to claim 1 or 2, wherein a part of the amplification system, hot wire power supply system, and pump drive system are installed in the same container and in the same atmosphere.