JP3363983B2 - 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 type acceleration detector equipped with a heating element and a temperature sensing means for detecting a temperature change corresponding to an acting acceleration.

[0002]

2. Description of the Related Art A conventional acceleration sensor is disclosed in Japanese Patent Laid-Open No. 3-17.
As disclosed in Japanese Patent No. 6669, a thin film resistance temperature sensor for a heater is provided in a case, an electric current is passed through the thin film resistance temperature sensor for a heater to heat the thin film resistance temperature sensor for a heater, and the temperature of the heated thin film resistance temperature sensor for a heater is adjusted. If the corresponding resistance value is detected and acceleration is applied in this state, an air flow will be generated in the case, and the heat of the thin film resistance temperature sensor for the heater will be removed along with the air flow, and the resistance of the thin film resistance temperature sensor for the heater will be removed. The value changes.

Since the change in resistance value of the thin-film resistance temperature sensor for heater corresponds to the acting acceleration, it is assumed that the acceleration is detected by detecting the change in resistance value.

[0004]

A conventional acceleration sensor is a thin-film resistance temperature sensor for a heater which also serves as a heating element for heating a gas inside a case and a temperature sensing element for detecting a temperature change caused by the action of acceleration. Since it is used, 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, in the conventional acceleration sensor, the thin film resistance temperature sensor for the heater serves both as the heating element and the temperature sensing element. Therefore, when the heat generation temperature is high, the thin film resistance temperature sensor for the heater may have a change with time due to temperature deterioration. However, there is a problem in that it causes variations in heat generation temperature and lowers the sensitivity of temperature detection.

The present invention has been made to solve the above problems, and an object thereof is to provide a heat wire type acceleration detector capable of accurately detecting the direction and absolute value of the acting acceleration and having little change over time. With the goal.

[0007]

In order to solve the above problems, a heat wire type acceleration detector according to the present invention is provided with a gas flow
A case that forms a closed space without passages, a gas enclosed in the space of the case , a heating element that heats the gas to form a temperature distribution in the space, and a case where acceleration acts on the case. An acceleration detecting temperature-sensing means for detecting a temperature change due to the movement of a gas having a temperature distribution in the space ;
The gas sealed in the case should be nitrogen gas or argon gas.
It is characterized by being a pressurized gas having a low thermal conductivity and consisting of gas .

Further, the temperature detecting means for acceleration detection of the heat wire type acceleration detector according to the present invention is arranged at a predetermined distance from the heating element in the acceleration acting direction.

Furthermore, a heat wire type acceleration detector according to the present invention comprises a temperature compensation temperature sensing means for detecting the ambient temperature, the acceleration detecting temperature sensing means based on the output signal from the temperature compensation temperature sensing means And an acceleration correction means for correcting the output signal of 1.

[0010]

The heat wire type acceleration detector according to the present invention comprises a heating element for heating a gas to form a temperature distribution in the space, and a temperature change due to the movement of the gas having the temperature distribution when acceleration acts on the case. Since the acceleration-sensing temperature-sensing means for detecting is provided, the absolute value of the acceleration and the direction in which the acceleration acts can be detected, and the acceleration-sensing temperature-sensing means is disposed at a predetermined distance from the heating element. Since a temperature lower than the temperature of the heating element is detected, it is possible to prevent a change with time caused by a high temperature and maintain stable sensitivity characteristics.

Further, in the heat wire type acceleration detector according to the present invention, a pressurized gas having a low thermal conductivity is used as the gas to be enclosed, and the gradient of the temperature distribution is increased to enhance the sensitivity of the detected temperature. Therefore, the acceleration change corresponding to the detected temperature can be accurately detected.

Furthermore, a heat wire type acceleration detector according to the present invention comprises a temperature compensation temperature sensing means for detecting the ambient temperature, the acceleration detecting temperature sensing means based on the output signal from the temperature compensation temperature sensing means Since the acceleration correction means for correcting the output signal is provided, it is possible to detect the acceleration by compensating the influence of the ambient temperature.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a structural diagram of a heat wire type acceleration detector according to the present invention. 1, a heat wire type acceleration detector 1 includes an upper case 2, a lower case 3 having an opening 3A, a heating element (heat wire) 4 provided in a space of the opening 3A, and an acceleration detecting temperature sensor. Means (cold wire) 5 and gas 6 enclosed in the space of the opening 3A
It consists of and.

The heating element (heat wire) 4 and the temperature sensing means (cold wire) 5 for acceleration detection are made of resistors such as platinum and tungsten, and the gas 6 has low thermal conductivity such as nitrogen gas and argon gas. Using the pressurized gas, the lower case 3 and the upper case 2 are brought into close contact with each other and bonded.

The heating element (heat wire) 4 is a lead wire 4
It is driven by an external power supply via a and 4b and generates a temperature sufficiently higher than the ambient temperature. On the other hand, the temperature detecting means (cold wire) 5 for acceleration detection is also preliminarily adjusted so as to have a predetermined resistance value by causing a minute current to flow from the external power source through the lead wires 5a and 5b.

The heat generated from the heating element (heat wire) 4 is conducted through the gas 6 and forms a temperature distribution corresponding to the distance from the heating element (heat wire) 4. Also, gas 6
By using a pressurized gas with low thermal conductivity such as nitrogen gas or argon gas for the heating element (heat wire)
A temperature distribution having a large temperature gradient corresponding to the distance from 4 is formed.

When the acceleration (G) acts in the direction (right) of the drawing (b) while the temperature distribution in the space of the opening 3A is stable, the gas 6 having a high temperature also moves in the direction P (right). The temperature of the temperature detecting means (cold wire) 5 for acceleration detection rises. As the temperature of the temperature detecting means (cold wire) 5 for acceleration detection rises, the resistance value also rises and the voltage value detected by the lead wires 5a, 5b increases. On the other hand, when the acceleration (G) acts in the opposite direction (left side), the gas 6 having a high temperature also moves to the left side and the acceleration detecting temperature-sensing means (cold wire).
The temperature of 5 decreases, the resistance value of the temperature sensing means (cold wire) 5 for acceleration detection also decreases, and the voltage value detected by the lead wires 5a, 5b decreases.

The acceleration detection temperature sensing means (cold wire)
5 is arranged at a predetermined distance D from the heating element (heat wire) 4 in the direction in which the acceleration (G) acts. In this way, the acceleration detecting temperature-sensing means (cold wire) 5 is arranged to increase the temperature gradient through the pressurized gas having low thermal conductivity such as nitrogen gas or argon gas, and the heating element (heat wire). ) 4 is set to detect a temperature sufficiently lower than the heat generation temperature, it is possible to accurately detect a temperature change due to a change in acceleration (G).

The lower case 3, heating element (heat wire) 4, and temperature sensing means for detecting acceleration (cold wire).
Each of 5 can be configured by an individual component, or all of them can be configured on the same silicon chip by using a semiconductor manufacturing process.

FIG . 2 is a functional block configuration diagram for detecting acceleration using the heat wire type acceleration detector according to the present invention. 2, the heating element (heat wires) 4 is driven by a constant current source Ih, to generate heat of high temperature corresponding to the resistance value R _H and a current value based on the Ih power (R H _* Ih ^2). On the other hand, temperature sensing means (cold wire) for acceleration detection 5
Is driven by a constant current source Il, and is set to a resistance value R _C that is the sum of the resistance value at room temperature and the resistance value corresponding to the temperature conducted from the heating element (heat wire) 4, and the voltage value V _G ( _RC * I
l) is output.

The voltage value V _G is the output of the heat wire type acceleration detector 1 corresponding to the resistance value R _C when the acceleration (G) is not acting, and is one end (( For example, it is input to the (+ input terminal). The other end (for example, the-input terminal) of the comparator 7 has a reference resistance _RS.
The voltage value _{V S} is input by, for example, when the acceleration (G) does not act, the voltage value _{V G} is set to be equal to the voltage value _{V S (V G = V S} ).

The comparator 7 calculates and outputs the deviation ΔV ₍₌ V G -V _S) of the voltage value _{V G} and the voltage value _{V S.} When the acceleration (G) acts in the direction of the figure (P direction), the resistance value R _{C of the} temperature detecting means (cold wire) 5 for acceleration detection increases and the deviation ΔV exceeds 0 (ΔV> 0). , Becomes a positive voltage value. On the other hand, when the acceleration (G) acts in the direction opposite to that shown in the figure, the temperature sensing means for detecting acceleration (cold wire).
The resistance value _{RC of} 5 decreases and the deviation ΔV is less than 0 (ΔV
<0), which is a negative voltage value.

The acceleration conversion means 9 is provided with a memory such as a ROM for storing the value of the acceleration Go corresponding to the deviation ΔV in advance, and is configured to output the acceleration signal Go corresponding to the input of the deviation ΔV.

FIG . 3 is a structural diagram of a heat wire type acceleration detector provided with temperature compensating temperature sensing means. In FIG.
The heat wire type acceleration detector 10 is provided with an opening 12B in the lower case 12 and includes a temperature compensating temperature sensing means 13 in the space of the opening 12B, or a temperature compensating temperature sensing means outside the lower case 12. 1 is configured so as to include 13 in FIG.
The heat wire type acceleration detector 1 of FIG. Opening 12
B is formed apart from the opening 12A so as not to be affected by heat from the heating element 4, and air is enclosed in the space so that the temperature compensating temperature sensing means 13 detects the ambient temperature. Constitute.

When the temperature compensating temperature sensing means 13 is formed in the space of the opening 12B, the semiconductor manufacturing process is used in the same silicon chip as the heating element 4 and the acceleration sensing temperature sensing means 5. To configure. Thus, by forming the temperature compensating temperature sensing means 13 and the acceleration detecting temperature sensing means 5 on the same silicon chip by the same manufacturing process, the temperature sensing means having the same characteristics can be configured, and both the temperature sensing means. It is possible to compensate for variations in characteristics between means and changes over time.

When the temperature compensating temperature sensing means 13 is provided outside the lower case 12 (the upper case 11 may be used), for example, the temperature sensing temperature sensing means for acceleration detection 5 and the temperature sensing means for temperature compensation having the same temperature characteristics are provided. 13 is attached to the case by bonding or the like.

When the heating element 4 is left to stand at a predetermined ambient temperature for a sufficiently long time without passing a current, the heating element 4, the acceleration detecting temperature sensing means 5 and the temperature compensating temperature sensing means 13 are set to the ambient temperature. Has been done. When a current is applied to the heating element 4 from this state, the heating element 4 generates heat corresponding to the power consumption determined by the supplied current value and the resistance value, and the temperature rises. In this case, the temperature of the heating element 4 has a value obtained by adding the ambient temperature to the temperature due to the power consumption.

The heat generated from the heating element 4 is conducted through the gas 6 such as nitrogen gas or argon gas to form a temperature distribution having a large temperature gradient, and the temperature is detected by the acceleration detecting temperature sensing means 5. Since the temperature detecting means 5 for acceleration detection is also set to the ambient temperature in advance, the temperature detected by the temperature detecting means 5 for acceleration detection is the temperature conducted by the heating element 4 plus the ambient temperature. For example, when the ambient temperature is 20 ° C. and the ambient temperature is higher than the predetermined temperature ΔT by 20 ° C., the temperature of the heating element 4 is a temperature obtained by adding the predetermined temperature ΔT to the temperature due to the power consumption, and the acceleration detecting temperature sensing means 5 is used. The detected temperature is also a value obtained by adding a predetermined temperature ΔT to the temperature of the temperature distribution at the position where the acceleration detecting temperature sensing means 5 is arranged.

On the other hand, since the temperature compensation temperature sensing means 13 is set to ambient temperature (reference temperature 20 ° C. + predetermined temperature [Delta] T), a sense acceleration detected based on the temperature detected by the temperature compensation temperature sensing means 13 The temperature detected by the warming means 5 can be compensated. Similarly, when acceleration (G) acts and heat is transferred by moving the gas 6 in the opening 12A, temperature compensation can be performed based on the temperature detected by the temperature compensating temperature sensing means 13. .

FIG . 4 is a functional block configuration diagram of a heat wire type acceleration detector provided with temperature compensating temperature sensing means and acceleration correction means. 4, as described with reference to FIG. 1, the heating element 4 and the temperature detecting means 5 for acceleration detection are driven by constant current sources Ih and Il, respectively. On the other hand, the temperature compensating temperature sensing means 13 is configured to be driven by the constant current source Il having the same current value as the acceleration sensing temperature sensing means 5.

When the heating element 4 is not driven (Ih =
0), the temperature sensing means 5 for acceleration detection and the temperature sensing means 13 for temperature compensation detect the ambient temperature, and since the temperature characteristics of both temperature sensing means are made equal, the resistance value R _C and the resistance value R _F are Equally, the detection outputs (voltage values) V _G and V _R from the acceleration detecting temperature sensing unit 5 and the temperature compensating temperature sensing unit 13 become equal (V _G = V _R ). On the other hand, when the heating element 4 is driven, the temperature rise from the heating element 4 is detected, the resistance value R _{C of} the acceleration detecting temperature-sensing means 5 is increased ( _RC > R _F ), and the detection output (voltage The value) V _G also increases (V _G > V _R ).

The acceleration correction means 15 includes a temperature comparison section 16,
A correction value output unit 17 and a correction value storage unit 18 are provided, and the detection output V _G from the acceleration detecting temperature sensing unit 5 is corrected based on the detection output V _R from the temperature compensating temperature sensing unit 13 to obtain the ambient temperature. The actual acceleration Go acting on the heat wire type acceleration detector 10 is detected by compensating the increase / decrease in the accompanying acceleration (G).

The temperature comparison unit 16 is composed of a comparison circuit such as a comparator, and compares the detection output V _R provided from the temperature compensating temperature sensing means 13 with a previously stored reference voltage value V _f corresponding to 20 ° C. and outputs the deviation [Delta] V _R of the detection output _{V R} and the reference voltage value _{V f} to the correction value output section 17.

The correction value output unit 17 takes in the detection output V _G and the deviation ΔV _R from the acceleration detecting temperature sensing means 5, and stores the acceleration correction value ΔG corresponding to the detection output V _G and the deviation ΔV _R in the correction value storage unit. It is read from 18 and provided to the acceleration conversion means 14. It should be noted that the correction value output unit 17 has an ambient temperature of 20
When the acceleration (G) does not act at 0 ° C., the output acceleration correction value ΔG is set to 0. Correction value storage unit 18
Is constituted by a memory such as a ROM, the detection output _{V G} and deviation [Delta] V _R detected based on the output _{V G} and the deviation [Delta] V _R deviation (V
_G - [Delta] V _R) as a reference, is set in the table to previously obtain in advance by experiments the correction value ΔG when the [Delta] V _R changes.

The acceleration converting means 14 is composed of a memory such as a ROM for converting the detected output V _G into the corresponding acceleration Go, a subtracter, etc., and after converting the detected output V _G into the acceleration Go, the acceleration Go is corrected. Deviation of value ΔG (Go-Δ
G) is calculated, and this deviation is output as the acceleration Go.
When the ambient temperature is 20 ° C. and the acceleration (G) does not act, the acceleration conversion unit 14 outputs the acceleration Go of 0.
To be set.

[0036] Thus, if the ambient temperature does not act acceleration (G) is at 20 ° C., the acceleration Go to be output is set to become 0, the temperature compensation acceleration correcting section 15 in response to a change in ambient temperature Therefore, the acceleration Go output from the acceleration converting means 14 can be set to be always 0 regardless of the change in the ambient temperature.

When the acceleration (G) acts, the detection output V _G of the temperature detecting means 5 for acceleration detection increases or decreases. Therefore, the acceleration output (correction value Δ) relating to the ambient temperature corresponds to the detection output V _G.
The acceleration Go which is G) is obtained from the acceleration conversion means 14.

The acceleration correction means 15 is arranged so that when the ambient temperature changes from the detected temperature when the acceleration detecting temperature sensing means 5 is at an ambient temperature of 20 ° C. and no acceleration (G) is applied.
This is an embodiment of the configuration in the case where the output Go from the acceleration conversion means 14 corresponding to the detection output V _G is non-linear.

FIG . 5 shows another embodiment of the acceleration correction means.
In this embodiment, the output Go from the acceleration conversion means 20 and the detection output V _G0 from the acceleration correction means 19 are linear.
Is shown. Acceleration correction means 19 the comparison circuit such as a comparator or an operational circuit of the subtracter like, the deviation of the detection output V _R from the detection output V _G and the temperature compensation temperature sensing means 13 of the acceleration detecting temperature sensing means 5, V _G0 (V _G −
V _R ) is calculated and output.

The acceleration conversion means 20 is the acceleration correction means 1
A memory such as a ROM for converting the deviation output V _G0 from 9 into the corresponding acceleration Go is provided, and the deviation output V _G0 is used as the acceleration G.
Convert to o and output.

[0041]

As described above, the heat wire type acceleration detector according to the present invention includes a heating element that heats gas to form a temperature distribution in the space and a temperature distribution when acceleration acts on the case. Since the acceleration detecting temperature sensitive means for detecting the temperature change due to the movement of the gas is provided, it is possible to detect the absolute value of the acceleration and the direction in which the acceleration acts, and the acceleration detecting temperature sensitive means is used as the heating element. Since a temperature lower than the temperature of the heating element is detected by arranging it at a predetermined distance from, it is possible to prevent a change with time caused by a high temperature and maintain stable sensitivity characteristics.

Further, in the heat wire type acceleration detector according to the present invention, a pressurized gas having low thermal conductivity is used as the gas to be enclosed, and the gradient of the temperature distribution is made large to enhance the sensitivity of the detected temperature. Therefore, the acceleration change corresponding to the detected temperature can be accurately detected.

[0043] Further, a heat wire type acceleration detector according to the present invention comprises a temperature compensation temperature sensing means for detecting the ambient temperature, the acceleration detecting temperature sensing means based on the output signal from the temperature compensation temperature sensing means Since the acceleration correction means for correcting the output signal of 1 is provided, it is possible to detect the acceleration that actually acts by compensating the influence of the ambient temperature.

[0044] Thus, excellent detection accuracy, and reliability,
A highly convenient heat wire type acceleration detector can be provided.

[Brief description of drawings]

FIG. 1 is a structural diagram of a heat wire type acceleration detector according to the present invention.

FIG. 2 is a functional block configuration diagram for detecting acceleration using the heat wire type acceleration detector according to the present invention.

FIG. 3 is a structural diagram of a heat wire type acceleration detector equipped with a temperature sensing means for temperature compensation.

FIG. 4 is a functional block configuration diagram of a heat wire type acceleration detector including a temperature compensating temperature sensing means and an acceleration correction means.

FIG. 5 is another embodiment of the acceleration correction means.

[Description of Reference Signs] 1, 10 ... Heat wire type acceleration detector, 2, 11 ... Upper case, 3, 12 ... Lower case, 3A, 12A, 12B ...
Openings 4, heating elements (heat wires) 4a, 4b, 5
a, 5b, 13a, 13b ... Lead wire, 5 ... Acceleration detecting temperature sensing means (cold wire), 6 ... Gas, 7 ... Comparator, 8, 14, 20 ... Acceleration converting means, 13 ... Temperature compensation temperature sensing Means (cold wire), 15 ... Acceleration correction means, 16 ... Temperature comparison section, 17 ... Correction value output section, 18 ... Correction value storage section, Ih, Il ... Constant current source, _RH ... Heating element resistance value, _RC ... acceleration detecting temperature sensing means resistance, R S _... reference resistance value, R F _... temperature compensation temperature sensing means resistance, V G _... acceleration detecting temperature sensing means sensing the output, V R _... the temperature compensation temperature sensing means Detection output, Go ... Acceleration conversion means output.

Continuation of the front page (56) Reference JP-A-4-369482 (JP, A) JP-A-3-176669 (JP, A) JP-A-4-369481 (JP, A) JP-A-63-236967 (JP , A) US Patent 2455394 (US, A) German Patent Invention 4243978 (DE, C2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01P 15/02-15/02

Claims (3)

(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, heating to form a temperature distribution in the space and heating the gas When acceleration is applied to the body and the case
An acceleration detecting temperature sensitive means for detecting a temperature change due to the movement of the gas having a temperature distribution in the space, and the gas sealed in the case is nitrogen gas or
Pressurized gas with low thermal conductivity consisting of Lgon gas
Heat wire acceleration detector, characterized in that that. 2. The heat wire type acceleration detector according to claim 1, wherein the temperature detecting means for acceleration detection is arranged at a predetermined distance from the heating element in an acceleration acting direction. 3. A temperature compensating temperature sensing means for detecting an ambient temperature, and an acceleration compensating means for compensating an output signal from the acceleration detecting temperature sensing means based on an output signal from the temperature compensating temperature sensing means. The heat wire type acceleration detector according to claim 1, further comprising: