CA1326712C - Gas rate sensor - Google Patents

Gas rate sensor

Info

Publication number
CA1326712C
CA1326712C CA000587737A CA587737A CA1326712C CA 1326712 C CA1326712 C CA 1326712C CA 000587737 A CA000587737 A CA 000587737A CA 587737 A CA587737 A CA 587737A CA 1326712 C CA1326712 C CA 1326712C
Authority
CA
Canada
Prior art keywords
rate sensor
gas rate
output signal
gas
pair
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CA000587737A
Other languages
French (fr)
Inventor
Tsuneo Takahashi
Tomoyuki Nishio
Masayuki Ikegami
Takahiro Gunji
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honda Motor Co Ltd
Original Assignee
Honda Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Honda Motor Co Ltd filed Critical Honda Motor Co Ltd
Application granted granted Critical
Publication of CA1326712C publication Critical patent/CA1326712C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C19/00Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
    • G01C19/58Turn-sensitive devices without moving masses

Abstract

Abstract of the Disclosure:
Disclosed is a gas rate sensor system which provides on output signal representing an angular velocity of the gas rate sensor when the gas flows more on one of its thermal sensing elements than on the other due to the effect of the angular velocity on the gas flow. The gas rate sensor system can carry out an arithmetic operation for correction of gas rate sensor output signal by renewing and using an effect value to meet the instantaneous temperature change in the gas rate sensor.

Description

"` 13~6712 ~

I`he present i~vention relates to a gas rate sensor which i6 capable of detecting an angular Yelocity which has an effect on the gas rate sensor.

In general, a ga2; rate sensor provides arl output ignal in reeponse to any difference between the output signals E;upplied from a pair of therElal sensing el~ent~, which dif~erence appears when the gas flow ejected from a gas noz~l~ deviates to rlow ~aore on one of the thermal ~ensing elements than on th~ othor due ~o the influence QD the gas flow by an applied motion ~who~;e angular velocity i to be deter3llined~ in terms of it~ speed and direction.

The angular velocity i~ determined by detecting a sn~all inbalance in the heat dissipation ~ro~n the pair o~ ~er~al sens1ng elements due to the dav:i ation of the gas flow, and re~ore t:he ~urrounding teD~perature change has a great effect on the 8en8itivity of the gas rate sensor, particularl~ an adverse ef ~ect of lowering the sensitivity o~

.

:

- 1326~12 the gas rate sensor. Thi5 necessitates the use o~
temperature compensating means in the gas rate sensor.

In an attempt to reduce ~he adverse ef~ect cause~ by the surrounding temperature the gas rate s2nsor i~ ~ub~ected ~o forced heating by using appropriate heaters, and the temperature within ~he ~as rate sensor is detected by appropriate te~perature æen~ors, and the temperature within the ga~ rate ~en~or i8 controlled 80 as to remain constant.

Di~advantageously, the ~ensiti~ity of the gas rate ~ensor and the o~fset ~alue remain too unstable to provide correct output signals until the temperature within the gas rat~ sen or has reached a stable condition a~ter connecting the electric heater to an associated power supply. As a matter of fact, no satisfactory gas t~mperature control ha be~n attained.

The present invention provide~ a gas rats sensor which i~ capable o~ correcting the gas rate sensor output signal to ~eet the instantane3us temperature change within the ga~ r~te æen or, allowin~ the temperatur~ within the gas rate s~nsor to vary.

More particularly, there is pro~lded a gas rate sen~or which can provide an output signal in response to any ~ 2 -~67~2 difference between the output signals from ~ pair of thermal sensing elements due to the ef~ect which an angular velocity Qxerts on the gas flow ejected from an associated noæzle over the pair of thermal sensing element~, i8 improved according to the present invention in that said gas rate sensor is eguipped with: means to effect temperature compensation of the gas rate sensor output signal by subtracting an o~fset value from the gas rate sensor output ignal: means to determine the resi~tances of the pair of the~mal sensing elements; means to detect the situation in which the resistances of the pair of thermal sensing elements increase or decrea~e simultaneously; mean~ to make a decision as to whether or not the gas rate sensor output signal remain~
within a predetermined tolerance when such situation is detected; and ~eans to permit the gas rate sensor output ~ignal to be used as a new offset value when the gas rate sensor output slgnal remains within a predeter~inad tolerance.

The present invention will he better understood from the ~ollowing description o~ a gas rate sensor equipped with temperature compensation means according to one 7 1 ~

embodiment of the present invention, which is shown in accompanying drawings:
Fig.1 shows diagramatically the.gas rate sensor e~uipped with temperature compensation means.
Fig.~ is a wiring diagram of resistance detection circuit;
Fig.3 is a longitudinal section of the gas rate sensor;
Fig.4 shows how the gas flow deviates when the gas rate sensor is moved at an angular ve].ocity to be determined; and Fig.5 is a graph representing the temperature-to-resistance characteristics of a pair of heating wires.
Fig.3 shows a gas rate sensor. Its casing 1 is open at one end, and is closed at the other end. The casing 1 has three longitudinal ridges 120 degrees apart from each other on its inner surface. When the gas rate sensor body 4 is put in the casing 1, these longitudinal ridges define three longitudinal channels 3.
As seen from the drawing, the gas rate sensor body 4 is composed of a holder section 5, a neck section 6 and a cylinder section 7. The holder section 5 serves to confine the gas within the casing 1. The holder section 5 has a pump compartment 8, and the pump
2~71~

compartment 8 contains a diaphragm type piezoelectric pump 9. When the pump 9 works, gas is drawn in the longitudinal channels 3 through the inlets 10 of the holder section 5.
After passing through a center nozzle aperture 11 and rectifying apertures 12 therearound on the top of the cylinder section 7, the gas is drawn into a sensor compartment 13 in the form of laminar flow. Then, the gas flows over a pair of heating wires 14a and 14b, which are used as thermal sensing elements and are positioned downstream of the sensor compartment 13.
~ Thereafter, the gas flows into the pump compartment 8, where it is directed to the longitudinal channels 3 by pumping. The pair of heating wlres 14a and 14b are put symmetrically with respect to the center line o-o of the nozzle aperture 11, as seen from Fig.4. When no force is applied to the gas rate sensor in a lateral ,~ direction, the gas is ejected from the nozzle aperture : 11, flowing straight along the center line o-o, and then each of the heating wires 14a and 14b will be exposed to the equal gas flow rate, and hence depriving each heating wire of the same amount of heat.
When a lateral force is applied to the gas rate i sensor to cause it to move at an angular velocity ~, s the gas flow will deviate from the center line o-o as - 5 - r 1~ (2n ~, .

13267~

shown in broken line. The amount of deviation is indicated by "~". As a result, the gas flows more on the heating wire 14a than on the heating wire 14b, thus causing unbalanced outputs from these heating 14a and 14b wires. Then, a signal representing the difference between the unbalanced outputs will appear at the output terminal of the gas rate sensor, and the output signal will be amplified by an amplifier circuit 15.
The polarity and amplitude of the amplified signal represents the direction and speed of the angular velocity of the gas rate sensor, respectively.
A printed board 16 of the amplifier circuit 15 is attached to the frange 2 of the casing 1 as seen from Fig.3. A hollow cylinder 17 contains the whole structure of the gas rate sensor.
As a matter of fact, a signal appearing at the output terminal of the gas rate sensor is likely to vary with surrounding temperature. The gas rate sensor output signal x is given by:
X = (R2(T)/R,(T)) - 1 (1) where Rl(T) stands for the resistance of the heating wire 14a at temperature T and Rz(T~ stands for the resistance of the heating wire 14b at temperature T.
If two heating wires l~a and 14b have a same temperature-to-resistance characteristic (then, R,(T) -- ~3267~ 2 is equal to R2(T)), and if the gas rate sensor has no angular velocity, the sensor output signal x will be zero as seen from the equation (1). In this ideal case no correction of gas rate sensor output signal will be required.
As a matter of fact, however, it is difficult to select and use a pair of heating wires 14a and 14b which have a same temperature-to-resistance characteristic. Usually, two heating wires 14a and 14b have different charac-teristics as shown in Fig.5.
Therefore, even if the gas rate sensor has no angular speed, the gas rate sensor output signal cannot be zero. Also, an error will be caused in detecting the angular velocity of the gas rate sensor because these heating wires have no same temperature-to-resistance characteristic.
Necessary temperature compensation of gas rate sensor output signal x will be effected according to the present invention as follows:
Fig.1 shows a gas rate sensor system according to one embodiment of the present invention. It camprises a gas rate sensor 18, a resistance detection circuit 19 for detecting the resistances ~l and R2 of the heating wires 14a and 14b used in the gas rate sensor 18, and a temperature compensation circuit for effecting a ~32~71~

temperature compensation of the gas rate sensor output x in response to the detected heating wire resistances Rl and R2 and the gas rate sensor output signal x.
Eig.2 shows the structure of the resistance detection circuit 19 as comprising a bridge having the heating wires 14a and 14b and two known resistances Ra, Rb, another known resistance series-connected to the bridge, and a constant voltage source 21 connected across the series connection of the bridge and the resistance Rc. An arithmetic processor 22 is connected across the series resistance Rc, and the arithmetic processor 22 uses the voltage El appearing across the series resistance Rc and the gas rate sensor output signal x to carry out the following arithmetic operation for determining the resistances R, and Rz of the heating wires 14a and 14b:
The following equations hold for the resistance circuit of Fig.2:
E-EI = (Rl t R2) Il - (Ra t Rb) I2 ~2) I2 - I (3) E, . I Rc (4) n 1 ;

-- 132~

From Equations (2), (3) and (4) the following equation is derived:
R,~R2-Rc(E-EI)(Ra + Rb)/E,(Ra -~ Rb)-Rc(E-EI) (5) Now, (R,+Rz) is represented by y, that is, (Rl+R2) = y (6) The gas rate sensor output signal x is given by Equation (1) as follows:
x = (R2/R,) - 1 (7) Thus, from Equations ~5), (6) and (7) Rl are derived as follows:
R, = y/(x+2) (8) R2 = y (x+1)/(x-~2) (9) By detecting the voltage E, across the resistance.
Rc the resistances Rl and R2 o~ the heating wires 14a and 14b can be determined from Equations (8) and (9) on real-time base.
The temperature compensation circuit 20 corrects the gas rate sensor output signal x by subtracting from the gas rate sensor output signal x an offset value which is initially registered in the temperature compensation cir~uit 20 in accordance with the characteristics of the heating wires 14a and 14b in the gas rate sensor 18. Then, the temperature compensation circuit 20 makes a decision as to whether or not the gas rate sensor output signal x remains within a ` ~2~7~

predetermined tolerance with respect to the offset value in case that the resistances Rl and R2 detected by the resistance detection circuit 19 increase or decrease together. In the affirmative case the temperature compensation circuit 20 will carry out correction by using the then gas rate sensor output signal x as a new offset value in place of the old one so that the gas rate sensor ou-tput signal x may become zero.
In the negative case the temperature compoensation circuit 20 will not change the offset value, regarding the gas rate sensor as being subjected to the influence by angular velocity.
As is apparent from the above. a gas rate sensor system according to the present invention determines the resistances of the pair of heating wires of the gas rate sensor to detect the temperature change of the surrounding atomosphere of the heating wires in terms of the simultaneous increase or decrease of the pair of heating wire resistances, presuming that the gas rate sensor has no angular velocity effect when it is decided from the situation in which the gas rate sensor output signal remains within a given tolerance that the then gas rate sensor output signal is nearly equal to the predetermined offset value, and then using the then 13~7~ 2 gas rate sensor output signal as a renewed offset value. Thus, a most appropriate temperature compensation of gas rate sensor output signal can be made to meet the temperature change of the atomosphere surrounding the pair of heating wires.
If a car is equipped with a gas rate sensor system according to the present invention for detecting any change in direction in which the car is running, the offset value can be renewed without stopping the car for that purpose.

- ll - FP t2

Claims (2)

?E EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A gas rate sensor which provides an output signal in response to any difference between the output signals from a pair of thermal sensing elements due to the effect which an angular velocity exerts on the gas flow ejected from an associated nozzle over the pair of thermal sensing elemetns, characterized in that said gas rate sensor is equipped with:
means to effect temperature compensation of the gas rate sensor output signal by subtracting an offset value from the gas rate sensor output signal;
means to determine the resistances of the pair of thermal sensing elements;
means to detect the situation in which the resistances of the pair of temperature sensor elements increase or decrease simultaneously;
means to make a decision as to whether or not the gas rate sensor output signal remains within a predetermined tolerance when such situation is detected; and means to permit the gas rate sensor output signal to be used as a new offset value when the gas rate sensor output signal remains within a predetermined tolerance.
2. A gas rate sensor according to claim 1 wherein a bridge circuit is composed of parallel connection of a series connection branch of said pair of temperature sensor elements and a series connection branch of first and second known resistances; a third resistance is connected to said bridge circuit; and the voltage appearing across said third resistance when a dc voltage is applied across the series connection of said bridge circuit and said third resistance, is determined, and an arithmetic operation is effected on the determined voltage and the gas rate sensor output signal to determine the resistances of said pair of temperature sensor elements.
CA000587737A 1988-01-13 1989-01-09 Gas rate sensor Expired - Fee Related CA1326712C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP63005396A JPH0614063B2 (en) 1988-01-13 1988-01-13 Gas rate sensor
JP005396 1988-01-13

Publications (1)

Publication Number Publication Date
CA1326712C true CA1326712C (en) 1994-02-01

Family

ID=11609991

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000587737A Expired - Fee Related CA1326712C (en) 1988-01-13 1989-01-09 Gas rate sensor

Country Status (5)

Country Link
US (1) US4951507A (en)
EP (1) EP0324620B1 (en)
JP (1) JPH0614063B2 (en)
CA (1) CA1326712C (en)
DE (1) DE68900610D1 (en)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5719333A (en) * 1994-01-20 1998-02-17 Honda Giken Kogyo Kabushiki Kaisha Acceleration sensor
JP3244208B2 (en) * 1994-02-07 2002-01-07 本田技研工業株式会社 Gas rate detector
JP3312227B2 (en) * 1994-02-23 2002-08-05 本田技研工業株式会社 Gas angular velocity sensor
JP3281169B2 (en) * 1994-03-24 2002-05-13 本田技研工業株式会社 Multi-axis gas rate sensor
US5786744A (en) * 1994-03-24 1998-07-28 Honda Giken Kogyo Kabushiki Kaisha Hybrid sensor
US5581034A (en) * 1995-01-13 1996-12-03 Remec, Inc. Convective accelerometer and inclinometer
US5808197A (en) * 1995-01-13 1998-09-15 Remec, Inc. Vehicle information and control system
US5835077A (en) * 1995-01-13 1998-11-10 Remec, Inc., Computer control device
JP4083652B2 (en) * 2003-09-19 2008-04-30 本田技研工業株式会社 Gas sensor control device
US7516660B2 (en) * 2004-05-21 2009-04-14 Met Tech, Inc. Convective accelerometer

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3500691A (en) * 1967-04-20 1970-03-17 Hercules Inc Angular movement sensing device
US4020699A (en) * 1976-02-05 1977-05-03 United Technologies Corporation Temperature stabilized fluidic angular rate sensor
US4026159A (en) * 1976-02-23 1977-05-31 United Technologies Corporation Fluidic angular rate sensor null error compensation
JPS5945944B2 (en) * 1980-03-27 1984-11-09 本田技研工業株式会社 gas rate sensor

Also Published As

Publication number Publication date
DE68900610D1 (en) 1992-02-13
US4951507A (en) 1990-08-28
JPH0614063B2 (en) 1994-02-23
JPH01180460A (en) 1989-07-18
EP0324620B1 (en) 1992-01-02
EP0324620A1 (en) 1989-07-19

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