CN1035573A - Gas alarm - Google Patents

Abstract

This invention is that fire is prevented rescuing device and equipment, utilizes mechanical principle to develop.With critical gas percussion power, make rocking bar run into the contact and send sound equipment, when gasoline or gas molecule concentration ↑ time, can in time report to the police the symptom of a trend of just can not causing danger like this.It is characterized in that: rocker structure.Its purposes: be mainly used in tank wagon, also can promote and be used for pressure vessel.

Description

Gas alarm

1, principle: simple, clear, clear.When gas expand into certain limit, have one impulsive force Pg, withstand the A end of OA bar, the OA bar is shifted onto the B contact with speed VA, sound then, just equal to report to the police, therefore design is to be contained in specially on the automobile that send oil, because of the road injustice, so adorned individual spring at the barycenter place, spring PV and gravity mg are considered in the design of spring, so in the ordinary course of things, spring are handled as static equilibrium.

2, this mechanism has one degree of freedom, and the corner φ of desirable tie-rod is a generalized coordinate, have during work the impulsive force Pg of gas ↑, speed V _A↑, because of the spring PV that road causes, the pulling force PS of spring and Tuo Li P и also have gravity mg, and friction force is omitted and has been disregarded.P и and PV have considered when the design spring, have also ignored in the computation process below.

3, potent mg, PS and the nonconservative force Pg relevant with initial point and final position, in when motion, mechanical energy and other forms of energy transform, when these are converted into other forms of energy as if consideration, concerning total system, total energy remains conservation.

4, water intaking average weighing apparatus position is the zero position of potential energy, promptly when φ=0, and V=0, spring tension P _S=k δ _S, the plumb position of D is moved and is y during work _DSo=(L)/2 φ is the potential energy V ' of corresponding gravity mg _D=-mg (L)/2 φ, because center of gravity ↑, institute thinks negative sign.Corresponding elastic force P _SPotential energy be V _S=0-1/2 k((L)/2 φ) ², V _S=-1/8 kL ²φ ², total potential energy power V at D ' some place _{D ' S '}=-1/2 L φ mg-1/8 kL ²φ ²

5, kinetic energy T, the T of computing system again _B=O T _A=1/2 PgV ²A+ 1/2 j.W ², tie-rod 0A rotates around the O axle.

φT _A＝ 1/2 Pg·L ²

²+ 1/2 〔 1/3 mL ²〕

²＝ 1/2 P _gL ^{2 2}+ 1/6 mL ²

²

6, according to E=T+V=constant, T so _A+ V _D=T _B+ V ' _D

1/2 PgL then ²

²+ 1/6 mL ²

²+ 0=0+ (1/2 L φ mg-, 1/8 kL ²φ ²),

1/2 PgL ^{2 2}+ 1/6 mL ²

²＝- 1/2 Lφmg- 1/8 kL ²φ ²-1

7, with Lagrangian function be situated between this topic L=T-V

L＝ 1/2 PgL ^{2 2}+ 1/6 mL ^{2 2}-〔- 1/2 Lφ·mg- 1/8 kL ²φ ²〕

＝ 1/2 PgL ²

²+ 1/6 mL ²

²+ 1/2 Lφmg+ 1/8 kL ²φ ²

PgL then ²φ "+1/3 mL ²φ " 1/2 Lmg-, 1/4 kL ²φ=0

（PgL ²+ 1/3 mL ²）φ″- 1/4 kL ²φ- 1/2 Lmg＝0-2

Following formula is the differential equation of motion of system for this reason, separates with the viewpoint of higher mathematics again

8, establish PgL ²+ 1/3 mL ²=A then 2 formulas is A φ " 1/4 kL ²φ-1/2 Lmg=0-3

3 formulas are y "=f(y, y ') differential equation of type, make (d φ)/(dt)=V, (d is then arranged ²φ)/(dt ²(d φ)/(dt)=V (dV)/(the d φ) of)=(dV)/(dt)=(dV)/(d φ), the substitution full scale equation gets AV (dV)/(d φ)-1/4 kL ²φ-1/2 mgL=0 is AV (dV)/(d φ)=1/4 kL ²φ+1/2 mgL variables separation and integration get AVdV= (1/4 kL ²φ d φ)+ 1/2 mgLd φ, 1/2 AV ²=1/8 kL ²φ ²+ 1/2 mgL φ i.e. 1/8 kL ²φ ²+ 1/2 mgL φ=1/2 (PgL ²+ 1/3 mL ²) V ²-4

4 formulas are the rotation equation of asking, thus but the motion of determination means

9, use the viewpoint of the mechanics of materials again, the flexural deformation of obtaining the quality m of tie-rod OA and rigidity, intensity, tie-rod OA is very important, because it directly has influence on φ, just directly has influence on alert locations and time of fire alarming.

R _x=O is here Pg, P _VBe used as static(al), because such P _sJust big, just f, θ are just maximum, ∵ P _sV＜P _sJ is f _V＜f _j, θ _V＜θ _j, at first stipulate the symbol of moment of flexure, when line of deflection protruded downwards here, M had been for just, so (d ²Y)/(d ²X)=(M) Ejy "=M=(P then/(Ej) _v+ P _g) x+P _И(x-(L)/2)-(P _s+ mg) (x-(L)/2) this formula is a deflection curve equation, integration gets Ejy '=1/2 x ²(P _v+ P _g)+1/2 x ²P _И-1/2 P _ИLx-(P _s+ mg) 1/2 x ²+ (Ps+mg) (L)/2 x+C

Put in order: Ejy '=1/2 x ²(Pv+P _g+ P _И-P _s-mg)+1/2 xL (P _s+ mg-P _И)+C

Integration Ejy=1/6 x again ³(P _v+ Pg+P _И-P _s-mg)+1/4 Lx ²(P _s+ mg-P _И)+Cx+D

When x=0, y=0, y '=0, then C=0, D=0 make x=L then

f _max＝y｜ _x＝L＝ 1/(Ej) ｛ 1/6 L ³〔P _v+P _g+P _И-P _s-mg〕+ 1/4 L ³〔P _s+mg-P _И〕｝-1

θmax＝y′｜ _x＝L＝ 1/(Ej) { 1/2 L ²〔P _v+P _g+P _И-P _s-mg〕+ (L ²)/2 〔P _s+mg-P _И〕｝-2

Then: f _Max=1/ (Ej) { 1/6 L ³(P _v+ P _g+ P _И-P _s-mg)+1/4 L ³(P _s+ mg-P _И)=0.0002L

θ max=1/ (Ej) { 1/2 L ²(P _v+ P _g+ P _И-P _s-mg)+1/2 L ²(P _s+ mg-P _И)=0.001 radian, but these two equation simultaneous are asked Jie, Fig. 2

10, simple diagram: 3 sides are arc, when arriving the contact like this, the gradient are just arranged, and are unlikely to bump.

11, in the whole computation process, symbol will be got clear, and unit will unify

12, to consider safety coefficient n at theoretical alert locations B,, send sound equipment so the actual alarm position is in the C contact.

13, this alarm is just taken away spring but be fixed on certain motionless place if not be contained on the walking part, a peace supporting-point, and just much whole computation process more just can prevent trouble before it happens.

14, select the garden column-shape stretching spring for use

P _gBe dynamic loading, but effect number of times и＜10 of variable load ³, and the amplitude that changes is little, so only carry out the static strength checking computations.Specific design method and step are as follows:

(1), and looks into and get its mechanical properties data according to working condition and actual conditions selected material.

(2) select spring index C, do not exceed 4～16 during common desirable C=5-8(ultimate limit state), and calculate penalty coefficient k value.

(3), consider the mean diameter of coil D of expection according to installing space ₂, estimate according to the C value and to get the spring wire diameter d, and look into the permissible stress of getting steel wire by table.

(4) tentative calculation spring wire diameter d ¹, by formula τ=k (8CP)/(π d ²)≤(τ) can get d ¹〉=1.6

$\sqrt{\frac{p_{\mathrm{m\; a\; x}}\mathrm{kC}}{\mathrm{［\tau \; ］}}}$

Must be noted that as spring and select for use listed first three of table to plant spring wire when making, the permissible stress of invar silk is decided by its σ _B, and σ _BChange with gauge of wire; (τ) in the factor is by estimating the σ that the d value of getting checks in again _BCalculating gets.So d that calculated by formula this moment ¹Value must be compared with estimating the d value of getting originally, if both equate or be very approaching that getting final product shaped is contiguous standard spring filament diameter d, and presses D ₂=Cd obtains D ₂If both differ bigger, then answer the reference calculation result, revaluation d value is looked into its σ again _BAnd calculate (τ), the substitution formula is carried out tentative calculation, can calculate D after meeting ₂When selecting other materials for use, because of its σ _BValue is subjected to the influence of spring wire vary in diameter little or irrelevant, so can not be subjected to above-mentioned restriction.

(5) obtain active spring coils according to deformation condition, use computing formula n=(Gd)/(8P of compression spring earlier _Maxc ³) go into max P _Maxj=P _И=Pv-mg and then with computing formula n=(Gd)/(8 (p of extension spring _Max-p ₀)) max P here _Maxv=P _g+ P _v-mg=P _SvEstimate repeatedly with these two formula

(6) obtain the dimension D of spring, D ₁, H.And check whether it meets installation requirement etc.As do not meet, then should select related parameter (for example C value) redesign else.During the design spring, in the time of considering alert locations, can the elongation of spring meet the demands.

15, send the circuit diagram 4 of sound equipment

Fig. 1: P _g, P _vImpact rocking bar OA, run into trigger, send sound equipment, individual safety coefficient is wherein arranged.

Fig. 2, be that material is tried hard to

Fig. 3, be the shape of rocking bar

The circuit diagram of Fig. 4, trigger

Claims (4)

1, technical field is that mechanical principle, reason power, material power, its technical characterictic are rocking bars under of the present invention.Be with critical numerical value P near blast _g, impact rocking bar, run into trigger, warning, P _gMust accurately measure, available Theoretical Calculation experimental data, be not to be the P of explosion time _g, but critical value, rocking bar have individual angle from the reference position to the trigger, and indeformable.

2, after Pg determines, must accurately calculate the φ angle, also to add a safety coefficient, it is characterized in that an acute angle.

3, the rigidity of rocking bar must meet the requirements, otherwise can influence warning, it is characterized in that f _Max=0.0002l, Q _Max=0.001 radian

4, trigger must be sensitive.

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