JP3332280B2 - Heat wire type acceleration detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat wire having a bridge circuit provided with a pair of heat-generating temperature sensing means or two pairs of heat-generating temperature sensing means, and capable of accurately obtaining a detection output corresponding to an acting acceleration. A type acceleration detector.

[0002]

2. Description of the Related Art A conventional acceleration sensor is disclosed in
As disclosed in Japanese Patent No. 6669, a thin-film resistance temperature sensor for a heater is provided in a case, and a current is supplied to the thin-film resistance temperature sensor for a heater to heat the thin-film resistance temperature sensor for a heater. If the corresponding resistance value is detected and acceleration is applied in this state, an air current is generated in the case, and the heat of the heater thin-film resistance temperature sensor is taken away by the air flow, and the resistance of the heater thin-film resistance temperature sensor is reduced. The value changes.

Since the change in the resistance of the heater thin-film resistance temperature sensor corresponds to the applied acceleration, the acceleration is detected by detecting the change in the resistance.

[0004]

A conventional acceleration sensor is a thin-film resistance temperature sensor for a heater which serves both as a heating element for heating a gas inside a case and a temperature sensing element for detecting a temperature change accompanying the action of acceleration. Because of this, there is a problem that the absolute value of the acceleration can be detected but the direction in which the acceleration acts cannot be detected.

Further, since the conventional acceleration sensor is composed of one thin-film resistance temperature sensor for heater, the temperature change of the thin-film resistance temperature sensor for heater due to the action of acceleration is not sufficient, so that acceleration detection accuracy cannot be increased. There are issues.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a heat wire type acceleration detector capable of accurately detecting the direction and absolute value of an acting acceleration.

[0007]

In order to achieve the above object, a heat wire type acceleration detector according to the present invention comprises a gas flow sensor.
A case for forming a sealed no road space, and a gas enclosed in the space of the case, provided in the case, to form a temperature distribution in the space and heating the gas space by the action of an acceleration A pair of heating type temperature sensing means for detecting a temperature change caused by the movement of gas in the inside, and a pair of reference resistances forming a pair of heating type temperature sensing means and a bridge circuit. .

Further, the pair of heat generating type temperature sensing means of the heat wire type acceleration detector according to the present invention is characterized by being arranged at a predetermined distance in a direction in which acceleration acts.

The gas sealed in the case of the heat wire type acceleration detector according to the present invention may be nitrogen gas or gas.
Is a pressurized gas made of argon gas having low thermal conductivity.

Further, the heat wire type acceleration detector according to the present invention is characterized in that a plurality of heat generating elements are arranged in the direction of action of acceleration, and provided on both sides of a pair of heat generating type temperature sensing means. I do.

Further, in the heat wire type acceleration detector according to the present invention, a bridge circuit is formed by forming a pair of reference resistors by a heat generating type temperature sensing means and providing the reference resistance together with the pair of heat generating type temperature sensing means in a case. It is characterized by.

[0012]

The heat wire type acceleration detector according to the present invention heats the gas sealed in the case to form a temperature distribution in the space, and detects a temperature change caused by the movement of the gas due to the action of the acceleration. A pair of heating type temperature sensing means for detecting, a pair of reference resistances forming a pair of heating type temperature sensing means and a bridge circuit, and a temperature change detected by the pair of heating type temperature sensing means when acceleration is applied. , The absolute value of the acceleration can be detected.

Further, since the pair of heat-generating temperature sensing means are arranged at a predetermined distance in the direction in which the acceleration acts, it is possible to detect the direction in which the acceleration acts.

Furthermore, since the gas to be sealed in the case has low thermal conductivity, and a pressurized gas can be used to set a large temperature gradient in the case, the acceleration that acts by increasing the sensitivity of the detected temperature Can be accurately detected.

Further, a plurality of heating elements are arranged on both sides of a pair of heating type temperature sensing means in a direction in which acceleration acts, and a temperature detected by each of the pair of heating type temperature sensing means when acceleration acts. Since the change can be increased, the detection sensitivity of the heat wire type acceleration detector can be increased.

Further, a pair of reference resistors constituting a bridge are also formed of a heating element and provided in a case together with a pair of heating type temperature sensing means, and each of the heating type temperature sensing means constituting the bridge when acceleration acts. Since the temperature change detected by each can be increased, the detection sensitivity of the heat wire type acceleration detector can be increased.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a heat wire type acceleration detector according to claims 1 to 3. In FIG. 1, a heat wire type acceleration detector 1 includes an upper case 2, a lower case 3 having an opening 3A, a pair of heat generating type temperature sensing means 4A and 4B provided in the space of the opening 3A, and an opening. A gas 6 to be sealed in the space of the part 3A, and a heat-generating type temperature sensing means 4A from the outside,
4B and a pair of reference resistors 5A and 5B forming a bridge circuit 7.

The pair of heat-generating temperature sensing means 4A and 4B are formed of a resistor such as platinum or tungsten, and are arranged at a predetermined distance D in the direction of action of the acceleration (G). The lower case 3 and the upper case 2 are closely adhered and sealed by using a pressurized gas having a low thermal conductivity, such as a gas. Further, a pair of heating type temperature sensing means 4A (resistance value R
1) 4B (resistance value R2) is connected by a lead wire, the lead wire is taken out of the case, and a reference resistor 5 provided outside the case is used.
A (b) is connected to A (resistance value r1) and 5B (resistance value r2), and has terminals a to d as shown in FIG.

Note that the heat wire type acceleration detector 1
Even if each of the upper case 2, the lower case 3, and the heat generating type temperature sensing means 4A, 4B is constituted by individual (discrete) parts,
The heat generating type temperature sensing means 4A, 4B may be provided by vapor deposition on a silicon chip using a semiconductor manufacturing process, and the opening 3A may be provided in the lower case 3 by etching.

Power supply (eg, voltage source V _I ) between terminals a and b
Is applied, the heat-generating temperature sensing means 4A and 4B generate heat corresponding to the power consumption, and correspond to the distance from the heat-generating temperature sensing means 4A and 4B in the space of the opening 3A as a heat source sufficiently higher than the ambient temperature. A temperature distribution is formed. In this state, the heat-generating temperature sensing means 4A and 4B have resistance values R1 and R1, respectively.
Because the R2, the terminal c divided voltage V _X by the resistance R1, R2 are generated.

Meanwhile, the reference resistor 5 a voltage source V _I to the terminal d
A, divided voltage V _Y in the resistance value r1, r2 occurs in 5B, the acceleration output of the bridge circuit 7 is in a state of (G) does not act (the potential difference V _X -V _Y) equilibrium state (output voltage = 0
V), the resistance values R1, R2, r1, and r2 are set (R1 = R2, r1 = r2).

In this case, the temperature distribution in the space of the opening 3A due to the heat sources of the heat generating type temperature sensing means 4A, 4B is also in an equilibrium state. Further, by using a pressurized gas having low thermal conductivity, such as nitrogen gas or argon gas, as the gas 6, a large temperature gradient in the space corresponding to the distance from the heat generating type temperature sensing means 4A, 4B. A temperature distribution is formed.

When the acceleration (G) acts from the equilibrium state as shown in FIG. 3 (b), the gas 6 moves in the P direction, and heat is transferred from the heating type temperature sensing means 4A to the heating type temperature sensing means 4B. It is. When the heat transfer (P direction) occurs, the thermal equilibrium in the space of the opening 3A is broken, and the temperature of the heat generating type temperature sensing means 4A decreases,
As the temperature of the heating type temperature sensing means 4B rises, the resistance value R1 of the heating type temperature sensing means 4A decreases and the resistance value R2 of the heating type temperature sensing means 4B increases.

[0024] by the action of acceleration (G), the resistance value R2 increases, the resistance value R1 decreases, the output of the bridge circuit 7 also becomes unbalanced, the potential difference V _X -V _Y is positive corresponding to the acceleration (G) detecting the value _{(V X -V Y> 0)} . On the other hand, when the acceleration (G) acts in the direction opposite to the direction shown in FIG. 2B, the opposite phenomenon occurs. The resistance value R1 increases and the resistance value R2 decreases, and the output of the bridge circuit 7 becomes the acceleration (G ) Is detected (V _X −V _Y <0).

As described above, the heat wire type acceleration detector 1 detects the magnitude of the acceleration (G) acting on the basis of the absolute value of the output (potential difference V _X -V _Y ) of the bridge circuit 7, and signifies the output ( Acceleration (G) due to potential difference V _X -V _Y positive or negative)
Detects the direction in which

Next, the output of the bridge circuit 7 (potential difference V _X
-V _Y ) will be described. FIG. 2 is a bridge circuit diagram of the heat wire type acceleration detector according to the present invention. FIG.
The bridge circuit 7 comprises resistance values R1 and R2 of the heat generating type temperature sensing means 4A and 4B and resistance values r1 and r2 of the reference resistance as shown in FIG. (For example, a voltage source V _I ) and output between terminals cd.

With respect to the ground (GND), the voltage V at the terminal c is
_X and the voltage V _{Y at the} terminal d are each calculated by Equation 1.

[0028]

(Equation 1)

From equation (1), the output potential difference Vo (= V _X -V _Y ) of the bridge circuit 7 is expressed as equation (2).

[0030]

(Equation 2)

In equation 2, by setting R1 = R2 and r1 = r2, an output potential difference Vo = 0 can be obtained in an equilibrium state where no acceleration (G) acts.

When the acceleration (G) shown in FIG. 1 acts from the equilibrium state, the resistance value R1 decreases by ΔR and the resistance value R2 increases by ΔR due to heat transfer (P direction), and the output potential difference Vo (=
V _X -V _Y ) is a value represented by Expression 3.

[0033]

(Equation 3)

As described above, the output potential difference Vo has a value proportional to the resistance change amount ΔR corresponding to the acceleration (G). On the other hand, when the acceleration (G) acts in the direction opposite to that in FIG. 1, the output potential difference Vo has a value (−
ΔR * V _I / 2R) is obtained.

FIG. 3 is a block diagram of a heat wire type acceleration detector according to a fourth aspect. In FIG. 3, the heat wire type acceleration detector 11 has heating type temperature sensing means 14A and 14B arranged at a predetermined distance D in an opening 13A of the lower case 13 and a plurality of heating type temperature sensing means 14A and 14B on both sides. Heating elements 16 (Ra1 to Ran, Rb1 to Rbn, Rc1
To Rcn) is different from FIG. Further, similarly to FIG. 1, the exothermic type temperature sensing means 14A, 14B and the reference resistance 1
5A and 15B constitute the bridge circuit 7 shown in FIG.

The heating elements 16 (Ra1 to Ran, Rb1 to Rb)
bn, Rc1 to Rcn), for example, connect each element in series, and connect a power supply between the terminals ef to generate heat. Also connected to voltage source V _I across terminals a-b of the bridge circuit 7,
The heat generating type temperature sensing means 14A and 14B generate heat.

The heating type temperature sensing means 14A, 14B and the heating element 16 (Ra1 to Ran, Rb1 to Rbn, Rc1 to Rc1)
Rcn), the resistance values of the heat generating type temperature sensing means 14A and 14B in a state where the temperature distribution in the space of the opening 13A due to the heat generation is balanced are R1 and R2, and the resistance values r1 and r2 of the standard resistances 15A and 15B and the resistance. The bridge output (output potential difference Vo) of the bridge circuit 7 formed by the values R1 and R2 is balanced (V
_X− V _Y = 0).

When the acceleration (G) acts in the direction shown in the drawing to cause heat transfer in the P direction in the space of the opening 13A, as described with reference to FIG. Heat is transferred to the resistor R1, the resistance R1 decreases, and the resistance R2
Increase. The decrease in the resistance value R1 and the increase in the resistance value R2 are caused by the heating elements 16 (Ra1 to Ran, Rb1 to Rbn,
Rc1 to Rcn) have a larger value (for example, k * ΔR) than the change in FIG.
o (V _X −V _Y ) is k * ΔR * V _I from the relation of the equations (1) to (3).
/ 2R.

As described above, since the heating element 16 is provided, the amount of heat transfer (temperature change) can be set large, and a large bridge output can be obtained for the same acceleration (G) as compared with the configuration of FIG. The detection sensitivity of the heat wire type acceleration detector 11 can be increased.

On the other hand, when the direction in which the acceleration (G) acts is reversed, the bridge output V of -k * ΔR * V _I / 2R
o is obtained. It should be noted that pressurized gas having low thermal conductivity, such as nitrogen gas or argon gas, is adopted as the gas 6 in FIG.
The configuration is the same as that described above.

FIG. 4 is a block diagram of a heat wire type acceleration detector according to a fifth aspect. In FIG. 4, the heat wire type acceleration detector 21 includes heat generating type temperature sensing means 24A, 24B in an opening 23A space of the lower case 23 and heat generating type temperature sensing means 25B corresponding to the standard resistors r1, r2 of FIG. ,
25A, and heat-generating type temperature sensing means 24A, 24B, 25A.
1 and 25B are different from the configuration of FIG.

[0042] Connect the power V _I across terminals a-b, exothermic temperature sensitive means 24A, 24B, exothermed 25A and 25B, in a state where thermal equilibrium of the opening 23A in the space is taken bridge circuit 7 outputs Vo ( Balance between terminals cd) (V _X -V _Y =
0) are set as the resistance values R1, R2, r2, and r1.

When the acceleration (G) acts in the direction shown in the drawing to cause heat transfer in the P direction in the space of the opening 23A, the heat-generating temperature sensing means 24A, 25A is changed from the heat-generating temperature sensing means 24B, 25B.
B transfers heat and the resistances R1 and r2 decrease, and the resistance R
2, r1 increases.

The resistance values R1 and r2 are reduced by -ΔR and -Δr.
And the increase in the resistance values R2, r1 is ΔR, Δr,
Bridge output Vo (V _X -V _Y) is represented by the number 4.

[0045]

(Equation 4)

As described above, the heating type temperature sensing means 25A (r
2) Since 25B (r1) is provided, the amount of heat transfer (temperature change) can be set large, and a large bridge output can be obtained for the same acceleration (G) as compared with the configuration of FIG.
The detection sensitivity of the heat wire type acceleration detector 21 can be increased.

The point that a pressurized gas having low thermal conductivity such as nitrogen gas or argon gas is used as the gas 6 and that the relative distance D between the heat-generating type temperature sensing means 24A and 24B is set in FIG. The configuration is the same as

[0048]

As described above, claims 1 to 3 are described.
The heat wire type acceleration detector according to the above has a low thermal conductivity, a pair of heat generating type temperature sensing means are arranged at a predetermined distance in a case in which pressurized gas is sealed, and a pair of heat generating type temperature sensing means And a pair of external reference resistors constitute a bridge circuit, so that heat transfer in the case caused by the action of acceleration can be detected by a change in the resistance value of the pair of heat-generating temperature sensing means. Based on this, the absolute value of the acceleration can be detected with high sensitivity, and the direction in which the acceleration acts can be detected.

In the heat wire type acceleration detector according to the present invention, a plurality of heat generating elements are provided in the case together with a pair of heat generating type temperature sensing means to increase the amount of heat transfer (temperature change) in the case. Therefore, the absolute value of the acceleration can be detected with higher sensitivity.

Further, in the heat wire type acceleration detector according to the fifth aspect, two pairs of heat generating type temperature sensing means are provided in the case, and a bridge circuit is constituted by four heat generating type temperature sensing means. The absolute value can be detected with higher sensitivity.

Therefore, it is possible to provide a high-sensitivity heat wire type acceleration detector capable of detecting the action direction and the absolute value of the acceleration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a heat wire type acceleration detector according to claims 1 to 3;

FIG. 2 is a bridge circuit diagram of the heat wire type acceleration detector according to the present invention.

FIG. 3 is a configuration diagram of a heat wire type acceleration detector according to claim 4.

FIG. 4 is a configuration diagram of a heat wire type acceleration detector according to claim 5;

[Explanation of symbols]

1,11,21 ... heat wire type acceleration detector, 2,1
2,22 ... upper case, 3, 13, 23 ... lower case, 3
A, 13A, 23A ... opening, 4A, 4B, 14A, 1
4B, 24A, 24B, 25A, 25B: Exothermic type temperature sensing means, 5A, 5B, 15A, 15B: Reference resistance, 6: Gas, 7: Bridge circuit, 16: Heating element, a, b, c,
d, e, f ... terminal, R1, R2, r1, r2 ... bridge resistance value, V _I ... voltage source, V _X ... voltage of the terminal c, V _Y ... voltage terminal d, Vo ... bridge output (V _X - V _Y ).

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-240573 (JP, A) JP-A-4-369481 (JP, A) JP-A-4-369482 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01P 15/12 G01P 15/02-15/03 G01P 9/00 G01C 19/00

Claims (5)

(57) [Claims] And 1. A case of forming a sealed space having no gas passage, and the gas sealed in the space of the case, provided in the casing, into the space and heating the gas A pair of exothermic type temperature sensing means for forming a temperature distribution and detecting a temperature change caused by the movement of the gas in the space due to the action of acceleration, and a pair of the exothermic type temperature sensing means and a bridge circuit. A heat wire type acceleration detector, comprising: a pair of reference resistors to be formed. 2. The heat wire type acceleration detector according to claim 1, wherein said pair of heat generating type temperature sensing means are arranged at a predetermined distance in a direction in which acceleration acts. 3. The gas sealed in the case is nitrogen.
2. The heat wire type acceleration detector according to claim 1, wherein the pressurized gas is a gas or an argon gas having a low thermal conductivity and a pressurized gas. 4. A heat wire type acceleration according to claim 1, wherein a plurality of heating elements are provided so as to be located in both sides of said pair of heat generating type temperature sensing means in the direction of action of said acceleration. Detector. 5. The bridge circuit according to claim 1, wherein said pair of reference resistors are formed by heat-generating temperature-sensitive means and provided in said case together with said pair of heat-generating temperature-sensitive means. Heat wire type acceleration detector.