CN102042945B - A method for measuring the concentration of oil mist in a closed gearbox - Google Patents

Abstract

A method for measuring the oil mist concentration of a closed gearbox: (1) establish a multi-parameter oil mist concentration model for a closed gearbox; (2) measure the pressure inside the gearbox with a pressure sensor; The equivalent volume formula of the oil mist derived from the theorem, according to the measured data, the oil mist concentration of the gearbox is calculated by mathematical formula; (4) the calculation formula of the oil mist concentration of the closed gearbox is fitted according to the calculated data; (5 ) According to the structural parameters of the gearbox, the gas leakage rate and gas leakage coefficient of the gearbox are calculated by mathematical formulas, and the original formula is corrected to obtain the calculation formula of oil mist concentration considering gas leakage. The present invention comprehensively considers the physical parameters affecting the oil mist concentration of the gearbox and the actual working state of the gearbox, and proposes a measurement method for the oil mist concentration of the gearbox under any instantaneous and steady-state working conditions through the conversion of physical quantities, which effectively reduces the Difficulty and cost of obtaining gearbox oil mist concentration.

Description

A kind of method of measuring closed gear case oil mist concentration

Technical field

The present invention relates to a kind of method of measuring closed gear case oil mist concentration, the measurement of the gear case oil mist concentration that is particularly useful for working condition is often changed.

Background technology:

The method of at present comparatively popular measurement oil mist concentration is divided into two kinds of the direct method of measurement and the indirect methods of measurement.Different according to principle, can be divided into four types, i.e. gravimetry, fluorescence spectrophotometry, infrared spectrophotometer and quantometer method.Wherein back three kinds belong to the direct method of measurement, and first kind belongs to the indirect method of measurement.But equipment price that above-mentioned measuring method adopts is expensive, and measuring method is complicated, must need the professional to measure it, and under the situation that the gear case operating mode changes, needs duplicate measurements again.

Therefore, still lack at present a kind of low cost, simple and convenient and can obtain the measuring method of gear case any time oil mist concentration.

Summary of the invention

Technology of the present invention is dealt with problems: overcome the deficiency of prior art, a kind of method of measuring closed gear case oil mist concentration is provided, can effectively reduce the difficulty and the cost that obtain the gear case oil mist concentration.

Technical scheme of the present invention is: a kind of measuring method of measuring closed gear case oil mist concentration, realize as follows:

(1) confirm interior all variablees that influence the gear oil mist concentration of the certain closed gear case of structure, said all variablees comprise: immersion oil amount u, rotating speed w, time t, lubricating oil temperature T and gas leadage coefficient c; Said oil mist concentration is meant percent by volume, promptly in the gear case in the unit volume mist of oil account for the percent by volume of mixed gas, its unit is 1; Foundation comprises the oil mist concentration model of all parameters that influence the gear case oil mist concentration, and promptly oil mist concentration k is expressed as the function of said four variablees;

(2) measure pressure p in the said closed gear case ₁Said measuring process divides three kinds of situation to carry out repeatedly respectively, that is: lubricating oil temperature, immersion oil amount are constant, measures time dependent pressure values and equilibration time under the different rotating speeds; Lubricating oil temperature, rotating speed are constant, measure time dependent pressure values and equilibration time under the different immersion oil amounts; Immersion oil amount, rotating speed are constant, measure different oil temperature time dependent pressure values and equilibration times down;

(3) according to the equivalent volume formula v=(p of mist of oil ₁-p ₀) v ₀/ p ₁, utilize pressure p in the closed gear case that measures respectively under above-mentioned three kinds of situation ₁, through formula k=v/v ₀=(p ₁-p ₀)/p ₁Calculate gear case oil mist concentration k respectively, wherein p ₀Be standard atmospheric pressure, v ₀Be gas volume in the standard atmospheric pressure lower tooth roller box;

(4) according to step (3) computing formula that resulting gear case oil mistiness degrees of data simulates closed gear case oil mist concentration of calculating;

(5) according to the structural parameters of gear case; Adopt formula

to calculate gear case quantity of gas leakage and gas leadage coefficient c=Q+1; Q is a quantity of gas leakage in the formula; μ is a coefficient of flow; A is the leakage hole area, and p is the pressure differential through the valve front and back, and ρ is the density of fluid; Computing formula to step (4) obtains is revised, and promptly multiply by a gas leadage coefficient c on the left side of the oil mist concentration computing formula equal sign of step (4), consider the oil mist concentration that gas leaks to the end.

The present invention's beneficial effect compared with prior art is: at first, use the survey crew that the present invention does not need expensive measuring equipment and specialty, effectively reduce the cost that obtains the gear case oil mist concentration; Secondly; Measuring method to present oil mist concentration need be carried out independent measurement to the oil mist concentration under each operating mode; Using the present invention only needs the measurement of carrying out a test of the gear case of model; Can obtain calculating its oil mist concentration, its operating mode need not remeasure when changing yet, and makes that obtaining of oil mist concentration value is more simple and convenient; At last, present measuring method can only be measured the gear case oil mist concentration that is in steady operation, uses the gear case oil mist concentration that the present invention can obtain any time.

Description of drawings

Fig. 1 is a method flow diagram of the present invention.

Embodiment

Process flow diagram of the present invention is as shown in Figure 1.Be example with a closed gear case below, specify the inventive method, but protection scope of the present invention be not limited to following instance:

Step (1): set up the oil mist concentration model that comprises all parameters that influence the gear case oil mist concentration.

For the certain closed gear case of structure, the variable that influences its oil mist concentration has gear teeth immersion oil amount u, gear rotational speed w, time t and lubricating oil temperature T, so oil mist concentration k can be expressed as the function of these several variablees, promptly

k＝f(u，w，t，T)，

Step (2): pressure in the prototype gear case.

Measure under the situation of three kinds of rotating speeds of two kinds of oil temperature, two kinds of immersion oil amounts pressure over time.Getting two kinds of oily temperature at this instance is that 100 ℃ and 150 ℃, two kinds immersion oil amounts are 1/4 and 1/3; Three kinds of rotating speeds are 2800n/m, 4200n/m, 5600n/m, so need to measure respectively: time dependent pressure and equilibration time when rotating speed is respectively 2800n/m, 4200n/m, 5600n/m during 100 ℃ of immersion oil amounts 1/4 of a. oil temperature; Time dependent pressure and equilibration time when rotating speed is respectively 2800n/m, 4200n/m, 5600n/m during 150 ℃ of immersion oil amounts 1/4 of b. oily temperature; Oil mist concentration value and equilibration time under the time dependent pressure when c. rotating speed is respectively 2800n/m, 4200n/m, 5600n/m during 150 ℃ of immersion oil amounts 1/3 of oil temperature; Time dependent pressure and equilibration time when rotating speed is respectively 2800n/m, 4200n/m, 5600n/m during 100 ℃ of immersion oil amounts 1/3 of d. oily temperature.

Step (3): the equivalent volume formula through the mist of oil derived by the thermodynamics theorem according to measurement data, calculates the gear case oil mist concentration with mathematical formulae.

Above-mentioned thermodynamics theorem is Boyle a---boyle's law: for certain mass, temperature-resistant ideal gas, the product value of its pressure and volume is a constant.The system pressure of setting up departments becomes p ₁, original system pressure is p ₀, being taken as standard atmospheric pressure, gas volume is v in the standard atmospheric pressure lower tooth roller box ₀, the pressure of increase is that the mist of oil by new generation provides, then at pressure p ₁Down, originally the volume of gas becomes v ₁, promptly

p ₁v ₁＝p ₀v ₀

So can get mist of oil equivalent volume formula be:

v＝v ₀-v ₁＝(p ₁-p ₀)v ₀/p ₁

Can get oil mist concentration is:

k＝v/v ₀＝(p ₁-p ₀)/p ₁

Integrating step (2) data of surveying, result of calculation is following:

Oil mist concentration value under different rotating speeds during 100 ° of immersion oil amounts 1/4 of table 1 oil temperature

Oil mist concentration value under different rotating speeds during 150 ° of immersion oil amounts 1/4 of table 2 oil temperature

Oil mist concentration value under different rotating speeds during 150 ° of immersion oil amounts 1/3 of table 3 oil temperature

Equilibrium concentration and equilibration time under the different rotating speeds during 100 ° of immersion oil amounts 1/4 of table 4 oil temperature

Equilibrium concentration and equilibration time under the different rotating speeds during 150 ° of immersion oil amounts 1/4 of table 5 oil temperature

Equilibrium concentration and equilibration time under the different rotating speeds during 100 ° of immersion oil amounts 1/3 of table 6 oil temperature

Step (4): the computing formula that simulates closed gear case oil mist concentration according to computed information.

With least square method step (3) institute computational data is carried out match, obtains the oil mist concentration formula and be:

k＝14.31744[u/(u+4.25)][(7.725×10 ^-9w-9.926×10 ^-5)t ²

+(6.396×10 ^-6w+0.01664)t+0.4028+0.014×(T-100)]×c

Gear teeth u is that immersion oil amount, w are that gear rotational speed, t are that time, T are that lubricating oil temperature, c are the gear case leadage coefficient in the formula.

Step (5): according to the gear box structure parameter, calculate gear case quantity of gas leakage and gas leadage coefficient, former formula is revised, obtain the oil mist concentration computing formula of considering that gas leaks with mathematical formulae.

The leakage mouth of gear case can be considered one 500 * 0.5 strip.There is pressure difference inside and outside the casing.Calculate formula according to gas flow:

$Q=\mathrm{\μA}\sqrt{\frac{2p}{\mathrm{\ρ}}}$

Q (m in the formula ³/ s) be quantity of gas leakage, μ (value 0.6～0.65) is a coefficient of flow, A (m ²) be leakage hole area (gear structure parameter, i.e. length and width and high usually), p (pa) is the pressure differential through the valve front and back, ρ (kg/m ³) (provide for the density of fluid.

Can get gas leakage front and back pressure reduction p according to Bernoulli equation is 1/970th of casing internal pressure added value, and the value that can get p is about 0～93.6Pa.

Can get quantity of gas leakage

$Q=186\×\sqrt{p}$

Through calculating can be 20% owing to the gas leakage causes the loss of pressure added value, and therefore, in the oil mist concentration model formation, should multiply by a gas leadage coefficient c is 1.2 (c=1+Q), so obtain revising back oil mist concentration computing formula is:

k＝17.1809[u/(u+4.25)][(7.725×10 ^-9w-9.926×10 ^-5)t ²

+(6.396×10 ^-6w+0.01664)t+0.4028+0.014×(T-100)]

The data that the used in the past weight method gained of following basis oil mist concentration comes gained oil mist concentration of the present invention in the proof list 6:

The test closed gear case of getting is of a size of 0.3m*0.3m*0.3m, and lubricating oil density is 870kg/m3

, oil temperature 100 ° of immersion oil amounts 1/3, rotating speeds use weight method gained oil mist concentration to be 92.23kg/m when being respectively 2800n/m, 4200n/m, 5600n/m ³, 126.38kg/m ³, 155.11kg/m ³

Using gained oil mist concentration of the present invention is 6.0,8.2,9.8, and the oil mist concentration here is meant percent by volume, and the mist of oil total amount that is converted in the unit volume is:

$6.0\×{0.3}^3\×870\×\frac{2}{3}=93.96\mathrm{kg}/m^3$

$8.2\×{0.3}^3\×870\×\frac{2}{3}=128.41\mathrm{kg}/m^3$

$9.8\×{0.3}^3\×870\×\frac{2}{3}=153.47\mathrm{kg}/m^3$

Can see, be no more than 1.5%, but the knowledge capital invention is effectively, reliably with gained oil mist concentration of the present invention and weight method gained data error.

In a word; The present invention has taken all factors into consideration physical parameter and the gear case actual working state that influences the gear case oil mist concentration; Through basic physical law physical quantity is changed; The equivalent volume method that a kind of oil mist concentration is measured has been proposed; Provide a kind of, overcome complicacy that oil mist concentration in the past obtains and the limitation that can only obtain oil mist concentration under the steady working condition, effectively reduced the difficulty and the cost that obtain the gear case oil mist concentration any measuring method of the oil mist concentration of instantaneous and steady state condition lower tooth roller box.

Claims (2)

1. A method for measuring the oil mist concentration of a closed gearbox, characterized in that the steps are as follows: (1) Determine all variables that affect the concentration of gear oil mist in a closed gearbox with a certain structure, and all variables include: oil immersion u, rotating speed w, time t, lubricating oil temperature T and gas leakage coefficient c; The oil mist concentration refers to the volume percentage, that is, the volume percentage of the oil mist in the unit volume of the gearbox in the mixed gas, and its unit is 1; an oil mist concentration model including all variables that affect the oil mist concentration of the gearbox is established, that is, the oil mist concentration is first The mist concentration k is expressed as a function of the oil immersion amount u, rotational speed w, time t, and lubricating oil temperature T, and then, the function is multiplied by a gas leakage coefficient c to obtain an oil mist concentration model considering gas leakage; (2) Measure the internal pressure _p1 of the enclosed gearbox; the measurement process is divided into three situations and carried out several times respectively, namely: the temperature of the lubricating oil and the amount of oil immersed are constant, and the pressure values changing with time under different rotating speeds are measured And the balance time; lubricating oil temperature and speed are constant, measure the pressure value and balance time changing with time under different oil immersion volumes; the oil immersion volume and speed are constant, measure the pressure value and balance time changing with time under different oil temperatures ; (3) According to the equivalent volume formula of oil mist v=(p ₁ -p ₀ )v ₀ /p ₁ , using the internal pressure p ₁ of the closed gearbox measured respectively in the above three cases, the formula k=v /v ₀ ＝(p ₁ -p ₀ )/p ₁ respectively calculate the oil mist concentration k of the gearbox, where p ₀ is the standard atmospheric pressure, and v ₀ is the gas volume in the gearbox under the standard atmospheric pressure; (4) According to the gear box oil mist concentration data calculated in the step (3), the function of the four variables of the oil immersion u, the rotating speed w, the time t, and the lubricating oil temperature T in the step (1) is represented. The formula for calculating the oil mist concentration of the closed gearbox; (5) According to the structural parameters of the gearbox, the formula

Calculate the gas leakage of the gearbox and the gas leakage coefficient c=Q+1, where Q is the gas leakage, μ is the flow coefficient, A is the area of the leakage port, p is the pressure difference before and after passing through the valve, and ρ is the density of the fluid ; Correct the calculation formula obtained in step (4), that is, multiply a gas leakage coefficient c in the oil mist concentration calculation formula in step (4), to obtain the oil mist concentration that finally considers gas leakage. 2. The method for measuring the oil mist concentration of a closed gearbox according to claim 1, characterized in that: the data fitting in the step (4) is to apply the least squares method for data fitting.

Images