JPH0654322B2 - Gas rate sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention utilizes a fact that when a rate (angular velocity) is applied to the sensor body, the heat radiation state of a pair of heat rays changes to detect the rate. The present invention relates to a rate sensor.

[Conventional technology]

FIG. 4 is a cross-sectional view showing the structure of a conventional gas rate sensor of this type (see Japanese Utility Model Laid-Open No. 58-17559).
In the figure, 1 is a closed container in which a gas 2 for rate detection such as helium or a mixture thereof is enclosed. A heater 3 formed of a metal resistance wire is wound around an entire outer periphery through an insulating coating 4, and the inside is It is a constant temperature bath. In addition to the gas 2 described above, a pair of heating wires 5 made of thin metal wires are stretched and arranged on the ceramic disk 6 in the closed container 1. In order to suspend the heating wires 5 on the disk 6. Of the metal columns are buried at regular intervals, and holes through which the gas 2 passing through the heating wire 5 passes are bored. A pump 7 for rectifying the gas 2 in a fixed direction is also arranged in the closed container 1. This pump 7 is made by laminating a piezoelectric element on a metal plate, and has a small hole at one place. When an AC voltage is applied, the pump 7 vibrates and gas 2 repeatedly inhales and exhausts from the small hole. It circulates in a fixed direction. Reference numeral 8 denotes an aluminum holder for fixing the ceramic disk 6, which supports a pump chamber cover 9, and has one end on which a nozzle 10 for rectifying the turbulent gas 2 into a laminar flow is mounted, and the other end. The side is in contact with the fixing ring 11. Reference numeral 12 is an exhaust pipe for gas 2, 13 is a hermetic base in which a ring-shaped rib is projection-welded to the flange portion of the closed container 1, and an introduction terminal 14 of, for example, 9 pins is embedded by a hermetic sealing process. Is connected to the lead terminal 15 of the heating wire 5, and the inside and outside of the sensor body are electrically connected. Further, the exhaust pipe 12 serves as an exhaust and gas filling port for replacing the gas in the closed container 1, and is sealed by welding or pressure welding after filling the gas 2.

FIG. 5 is a block diagram showing a system-specific configuration of the gas rate sensor having the above configuration. Inside the closed container 1, a rate detection system A such as the gas 2, the heat ray 5 and the pump 7, a signal conversion system B having a bridge circuit for converting the detection signal into an electric signal, an amplification system C for the converted signal, etc. Is provided.
Further, outside the container, a heat ray power supply system D for driving the heat ray 5 is provided.
A pump drive system E for driving the pump 7, a heater temperature control system F for controlling the temperature of the heater 3 to make the interior of the container a constant temperature bath, a power supply system G for supplying power to each system, and the like are provided. There is.

Next, the operation will be described. The hot wire 5 is always heated by a constant electric current, and is uniformly cooled by the constant laminar gas 2 when the rate is not applied to the sensor body. When a rate is applied to the sensor body, the gas 2 in the closed container 1 is biased by the Coriolis force, and the heat radiation state of the pair of heating wires 5 changes. This change appears as a change in the temperature of the heating wire 5, and is further converted into an electric signal by a bridge circuit having the heating wire 5 as one side, and taken out as a rate output. Then, the traveling position of the automobile or the like is detected by this rate output, and the function as a direction sensor is fulfilled.

[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 container becomes stable after the power is turned on is long,
In addition, since the temperature balance of each component changes depending on the ambient temperature, the offset voltage tends to fluctuate, and if left for a long time, the electronic components and the circuit board absorb moisture to change the impedance and the characteristics become unstable. There was a point.

The present invention has been made in view of these problems, and has a short warm-up time after power-on, stable offset voltage with respect to ambient temperature, and stable gas characteristics even after being left for a long time. A rate sensor is provided.

[Means for solving problems]

In the gas rate sensor of the present invention, a pair of heat wires are arranged in a hermetically sealed container in which gas is enclosed, and a resistor forming a bridge circuit is provided with each of the pair of heat wires as one side, and a rate is applied to the sensor body. When the temperature change generated in the heat wire due to the flow of the gas is detected as a change in the resistance value of the heat wire and is converted into a change in the output electric signal of the bridge circuit to detect the rate, the bridge circuit is configured. The resistor is provided in the same sealed container as the pair of heating wires.

[Action]

In the gas rate sensor of the present invention, since the pair of heat rays and the resistor forming the bridge circuit are provided in the same closed vessel as the heat rays, the temperature in the closed vessel is stable quickly, and the influence of ambient temperature It is hard to receive, and the impedance change of each part is small even if left for a long time.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of the present invention, and the same reference numerals as those in FIG. 4 of the prior art indicate the same constituent elements. In the figure, 1 is a hermetically sealed container having an internal thermostatic chamber, 2 is a gas enclosed in the container, 3 is a heater, 4 is an insulating coating, 5 is a pair of heating wires, 6 is a ceramic disk for supporting the heating wires 5, 7 Is a pump for circulating the gas 2, 8 is a holder for holding the heating wire 5, the pump 7, etc., 9 is a pump chamber cover, 10 is a nozzle for ejecting the gas 2, 11 is a fixing ring for the holder 8,
Reference numeral 12 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 of the heating wire 5, which is connected to the introduction terminal 14. Reference numeral 16 is a circuit board on which resistors R ₁ and R ₂ that form a bridge circuit with the pair of heat wires 5 as one side are mounted, and are arranged in the same atmosphere as the heat wires 5 in the closed container 1, Two
It is arranged in a space that does not disturb the flow of.

FIG. 2 is a block diagram showing the constitution of each system, and as shown in the figure, the rate detection system A in the closed container 1 (in the sensor body).
A signal conversion system B and a part of another system, for example, an amplification system C.
Part of is incorporated.

Further, FIG. 3 shows a signal conversion system B formed on the circuit board 16.
3 is a circuit configuration diagram showing details of FIG. As described above, the bridge circuit is composed of the resistors R ₁ and R ₂ with the pair of heating wires 5 as one side (R, L). Further, a resistor R ₃ for adjusting the offset voltage and a variable resistor VR are provided, and further, an equivalent resistor R ₄ and a noise removing capacitor C ₁ corresponding to the bridge circuit for canceling leakage currents from the amplification system C are provided. , C ₂ are 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 heating wire 5 as in the conventional case, and this change amount is converted into an electric signal by the bridge circuit shown in FIG. It Then, this electric signal is amplified and output, and a detection signal can be obtained in accordance with the above rate.

Here, since the signal conversion system B such as the bridge circuit is provided in the same atmosphere as the rate detection system A, the influence of the temperature dependence of each component in the closed container 1 is extremely small. There is. That is, each component on the circuit board 16 has temperature dependency, which becomes an unstable factor when detecting a minute change as in the present embodiment. However, by storing each of these parts in the same atmosphere as that of the rate detection system A, the temperature change of each part can be kept within the change range of the same condition, and the instability factor can be eliminated. . In this embodiment, the above components are placed in a closed container 1 in which a gas 2 is enclosed and the gas 2
I try to balance it with the temperature. At this time, if the circuit board 16 and the like are made of a material having a relatively good thermal conductivity and are thermally coupled to the closed container 1 with a material having a good thermal conductivity, the circuit board 16 and the like have a minimum thermal resistance. It has a simple mounting structure. With such a structure, the same temperature conditions are satisfied, highly stable characteristics are obtained, and the warm-up time from power-on is minimized. It is shortened to about / 4. Further, the stability of offset voltage and the like increases with respect to fluctuations in ambient temperature, and the characteristics become stable even after being left for a long time.

The gas rate sensor of the present invention is, for example, a traveling position detecting device in an inertial navigation device for an automobile or a special vehicle, an unmanned guided vehicle or a guiding device for a self-propelled robot, a motion or attitude control device for a moving or displacing object, It can be used as a direction detection sensor for various measuring devices.

〔The invention's effect〕

As described above, according to the present invention, since the circuit components of the signal conversion system that converts the detection signal from the heat ray into the electric signal are arranged in the same sealed container as the heat ray, the warm-up time after power-on is short. Thus, the effect that the offset voltage with respect to the ambient temperature is stable and the characteristics are stable even after being left for a long time is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a block diagram showing the constitution of each system, FIG. 3 is a circuit constitution diagram showing the details of the signal conversion system of FIG. FIG. 5 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 ...... sealed container 2 ...... gas 5 ...... hot wire 7 ...... pump 10 ...... nozzle 16 ...... circuit board R _{1, R 2} ...... resistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Matsumoto 1-35-1, Oshidate-cho, Fuchu-shi, Tokyo (56) Reference JP-A-58-37566 (JP, A)

Claims (3)

[Claims] 1. A pair of heating wires are arranged in a hermetically sealed container in which a gas is sealed, and a resistor forming a bridge circuit is provided with the heating wires as one side, and when a rate is applied to the sensor body, The bridge circuit is configured in a gas rate sensor that detects a temperature change generated in the heat wire due to the flow of the gas as a resistance value change of the heat wire and converts it into a change in an output electric signal of the bridge circuit to detect the rate. A gas rate sensor characterized in that a resistor is provided in the same closed container as the pair of heating wires. 2. A container in which a fixed resistance portion of an offset voltage adjustment circuit which is a part of a signal conversion system and an equivalent resistance corresponding to a bridge circuit for canceling out a leakage current from an amplification system are the same container. The gas rate sensor according to claim 1, wherein the gas rate sensor is installed in the same atmosphere. 3. The gas rate sensor according to claim 1 or 2, wherein a part of the amplification system, the heat ray power supply system, and the pump drive system are installed in the same container and the same atmosphere.