CN104295425A - Oil injection law measuring system and method - Google Patents

Abstract

The invention relates to an oil injection law measuring system and method. In the measuring system, an oil injection hole and a piezoelectric sensor are correspondingly arranged, and a distance adjusting device is additionally arranged to be used for adjusting the distance between the piezoelectric sensor and the oil injection hole. According to the method, the output signal start-stop interval time of the sensor and the oil injection extended period are compared, the distance adjusting device is driven to adjust the distance between the sensor and the oil injection hole until the output signal start-stop interval time of the sensor and the oil injection extended period are basically the same and the output waveform of the sensor is mostly stable, and at the moment, the position of the sensor is the optimum flow measuring position. By means of the oil injection law measuring system and method, it is guaranteed that measuring can be conducted in a liquid phase fluid area, and meanwhile measuring stability can be guaranteed.

Description

A kind of fuel injection characteristic measuring system and method for measurement

Technical field

The present invention relates to a kind of fuel injection characteristic measuring system and method for measurement.

Background technique

The fuel supply of motor is generally apply fuel-injected method to generate tiny oil droplet group, and object is the evaporation pneumatization increasing fuel oil, increases combustion heat release amount.This is a quite complicated problem.Fuel spray is not only subject to fuel injector structure form (apply in diesel engine more be multiple orifice nozzle), the impact of jet pressure, needle lift, is also subject to the impact of inner pressure of air cylinder, temperature, air motion (comprising macroscopic view flowing and turbulent flow).It is very complicated again that fuel oil enters the oil bundle generative process after cylinder, and it comprises the atomization of oil bundle, Oil Droplet Breakup, oil droplet collision and coalescence, and oil bundle is rebuffed and the evaporation etc. of fuel oil Multiple components; The major component oil droplet of oil bundle is very intensive, and can form a liquid core from oil sprayer outlet, its length receives again the impact of fuel injector structure.

Application number is the Chinese patent document " the effective actual internal area method of measurement in each hole of a kind of diesel injector " of 20110095233, relates to the injection pressure being measured nozzle opening ejection by piezoelectric transducer, and to be converted fuel injection quantity by injection pressure.

Above-mentioned patent calculates fuel injection quantity by strokes law and momentum conservation.But in fact, sprayed oil beam can be divided into two regions successively, i.e. liquid phase stream tagma and non-liquid fluid zone after nozzle opening ejection, in liquid phase stream tagma, spraying main manifestations is fluid oil bundle; And in non-liquid fluid zone, fluid oil bundle is atomized gradually.

Only in liquid phase stream tagma, measuring pressure can obtain the corresponding relation with flow more accurately, and in non-liquid fluid zone, the linearity is very poor.How to ensure to measure and carry out in liquid phase stream tagma being very crucial problem.

Summary of the invention

The object of this invention is to provide a kind of fuel injection characteristic measuring system and method for measurement, in order to ensure to measure the stability ensureing in liquid phase stream tagma to measure simultaneously.

For achieving the above object, the solution of the present invention comprises:

A kind of fuel injection characteristic measuring system, comprise oil sprayer (5), the upper nozzle opening arranged of oil sprayer (5), the piezoelectric transducer (6) that arrange corresponding to nozzle opening, piezoelectric transducer connects measuring device, also be provided with the metering module (4) for recording described oil sprayer (5) injection time, metering module (4) connects described measuring device, for regulating the roll-setting gear of described nozzle opening and piezoelectric transducer distance.

Fuel injection characteristic measuring system also comprises a high pressure oil pump, and high pressure oil pump connection pumps fuel oil and the accumulator making oil pressure stable in order to store high pressure oil pump, and the output circuit of accumulator connects described oil sprayer.

Described roll-setting gear is the roll-setting gear (9) driving the motion of described piezoelectric transducer.

Described measuring device is computer terminal (10), computer terminal (10) connects described metering module (4) and manometric module (8) by collecting device (7), and described piezoelectric transducer (6) connects described collecting device (7) by described manometric module (8).

Fuel injection characteristic method of measurement, step is as follows:

1) before measuring: start-stop t interval time measuring piezo sensor output signal ₀, and signal output waveform; By metering module record oil injection duration size T;

2) compare piezo sensor output signal start-stop interval time and oil injection duration size, if two times are unequal, then drive the distance between roll-setting gear adjustment piezoelectric transducer and nozzle opening, until two times are equal, and sensor output waveform is steady;

3) start to measure.

The present invention is in measuring system, and nozzle opening is corresponding with piezoelectric transducer to be arranged, and adds a roll-setting gear, for regulating the distance between piezoelectric transducer and nozzle opening.

The present invention: compare sensor output signal start-stop interval time and oil injection duration size, and drive the distance between roll-setting gear adjustment sensor and nozzle opening, until two times are substantially equal, and sensor output waveform the most steady time till, now sensor position is optimum flow measuring position.

Sensor output signal start-stop interval time is t ₀, oil injection duration size is T; T ₀time number is defined as, with letter with the ratio of T represent, that is: with value can compare nozzle opening place fuel flow and oily size of restrainting arbitrary cross section place flow.When when value equals 1, represent this section fuel flow equal with nozzle opening place fuel flow (consider error component, can be value is relaxed near 1).Now, the flow measuring this section oil bundle can obtain the flow at nozzle opening place.Certain section of oil bundle is only just made in liquid phase stream tagma value equals 1, and now, the oil bundle between nozzle opening and this cross section is in liquid phase region, the flow at nozzle opening place, and no matter mean flowrate or instantaneous flow are equal to the corresponding flow of this section.And non-liquid fluid zone in, the mean flowrate at mean flowrate and the nozzle opening place at oil bundle arbitrary section place is still ratio, but both instantaneous floies no longer include one-to-one relationship.

In theory, whole liquid phase region value all equals 1, sensor is placed in arbitrary position therebetween, but distance nozzle opening is nearer, oil burning jet is emitted through in intensive, speed is also comparatively large, splashes and collides the phenomenon of interference clearly each other, can cause the signal concuss that sensor exports, measurement result departs from exact value, therefore needs the position, liquid phase region that selected sensor output waveform is the most stable.

Accompanying drawing explanation

Fig. 1 is measuring system pie graph of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the present invention will be further described in detail.

If Fig. 1 is a kind of measuring system of the present invention.Comprise: a pressurization of the fuel oil by low pressure oil way D pumps fuel oil and the accumulator 2 making oil pressure stable to provide the high pressure oil pump 1, of high pressure fuel to be connected to store high pressure oil pump with high pressure oil pump 1; One be connected in the output circuit of accumulator 2 in order to by the high pressure fuel injection in accumulator 2 to the oil sprayer 5 in downstream; One for accepting oil sprayer 5 oil spout bundles and measuring the piezoelectric transducer 6 (as quartz piezoelectric sensor) of oily Shu Chongli, the signal that piezoelectric transducer 6 produces by amplifier 8, be exaggerated after signal enter in a data acquisition unit 7; One is positioned to measure the measuring apparatus 4 of oil injection duration on oil sprayer 5, and this measuring apparatus 4 is connected to data acquisition unit 7; One for regulating the roll-setting gear 9 of piezoelectric transducer 6 and nozzle opening distance, roll-setting gear 9 is connected with piezoelectric transducer 6.A terminal unit 10, this terminal unit connection data collecting device 7, gather, read and analysing and processing signal, row relax of going forward side by side, can carry out images outputting.

Roll-setting gear 9 can be arranged on oil sprayer 5, also can be arranged on piezoelectric transducer 6.As a kind of mode of execution, as Fig. 1, roll-setting gear 9 and piezoelectric transducer 6 are in transmission connection, and keep and piezoelectric transducer 6 and nozzle opening axes normal, built-in motor and gear, and piezoelectric transducer 6 can be made slowly movable with fine tuning distance.

Nozzle opening and piezoelectric transducer have relation one to one, and can arrange many group nozzle openings and piezoelectric transducer, Fig. 1 only depicts a nozzle opening and a piezoelectric transducer simultaneously.Piezoelectric transducer can be fixed on to be measured on plate, measures plate and is between nozzle opening and piezoelectric transducer, directly born the mist of oil of ejection by measurement plate, avoid polluting piezoelectric transducer, be also convenient to change piezoelectric transducer.

Accumulator 2 end is also provided with the pressure-detecting device 3 measuring input oil sprayer fuel pressure, this pressure-detecting device 3 connection data collecting device 7, and force value is used for the reference in measuring phase.

Method of measurement:

Before formal measurement, first to determine best measuring position.Piezoelectric transducer and nozzle opening distance can be regulated by as far as near-earth, also can from the close-by examples to those far off regulate.

Such as: first piezoelectric force transducer 6 is placed in nozzle opening pole nearby, injection pressure, fuel injection pulsewidth, driving voltage electric current etc. remain unchanged, multi-injection fuel oil, relatively sensor output signal start-stop interval time and oil injection duration size, and handle roll-setting gear 9 and regulate distance between sensor and nozzle opening, until two times are substantially equal, and terminal 10 show the output waveform of sensor 6 the most steady time till, now sensor position is optimum flow measuring position.

Measure and start, high pressure oil pump 1 starts and the fuel oil pumping high oil pressure enters in accumulator 2, and the oil pressure of the stable fluctuation of accumulator 2, ensures that the injection pressure in oil sprayer 5 is constant, oil sprayer 5 commencement of fuel injection, oil bundle percussive pressure power sensor 6 compression face.Oil sprayer 5 commencement of fuel injection rises in the process of end of injection, pressure-detecting device 3 whole process provides instantaneous fuel injection pressure signal, measuring device 4 provides oil spout initiatic signal and oil injection duration signal, piezoelectric transducer 6 provide the signal of instantaneous impulse force, impact initiatic signal and impact duration signal, these signals enter in terminal 10 via data acquisition unit 7, in conjunction with initial parameters, can the fuel injection characteristic curve of Graphical output oil sprayer 5 under the conditions such as corresponding oil pressure and oil injection duration.

As the precondition measured, the determination of best observation position is very important, is directly connected to the validity of surveyed data.Must repeatedly oil spout, fine setting distance, until time base is originally 1, smooth steady can the most for the waveform that exports of sensor simultaneously.In addition, often change the initial conditions such as an injection pressure, all will redefine a suboptimum observation position.

The derivation of the instantaneous flow at sensor compression face place.

Suppose that the fuel mass on shock transducer surface is δ m, and instantaneous flow is q in certain section of very short time interval δ t _v, fuel density is ρ, and oil bundle is S with sensor surface area of contact, and oily Shu Qianduan speed is v, and the impulse force on oil bundle shock transducer surface is F _t, crash type (perfectly elastic impact, imperfect elastic collision, perfectly inelastic impact) is determined by collision coefficient k (k scope is 1 ~ 2).

Have according to relevant theorem:

F _tδt＝kδmV

$F_t=k\stackrel{\·}{m}v$

$F_t={\mathrm{k\ρq}}_v\frac{q_v}{S}$

Obtain the instantaneous flow of sensor compression face place oil bundle:

$q_v=\sqrt{\frac{F_{t}S}{\mathrm{k\ρ}}}$

Known by the conservation of mass, time, the instantaneous flow q at nozzle opening place ₀instantaneous flow q is restrainted with sensor place oil _vpass be:

q ₀＝q _v

Then can derive nozzle opening instantaneous flow q ₀for:

$q_0=\sqrt{\frac{F_{t}S}{\mathrm{k\ρ}}}$

When other conditions are known, can by the instantaneous impulse force F of measurement _tcalculate nozzle opening place instantaneous flow q ₀, F _tchange in time, same time dependent q can be obtained ₀, i.e. nozzle opening fuel injection characteristic.

Be presented above concrete mode of execution, but the present invention is not limited to described mode of execution.Basic ideas of the present invention are above-mentioned basic scheme, and for those of ordinary skill in the art, according to instruction of the present invention, designing the model of various distortion, formula, parameter does not need to spend creative work.The change carried out mode of execution without departing from the principles and spirit of the present invention, amendment, replacement and modification still fall within the scope of protection of the present invention.

Claims (5)

1. a fuel injection characteristic measuring system, comprise oil sprayer (5), the upper nozzle opening arranged of oil sprayer (5), the piezoelectric transducer (6) that arrange corresponding to nozzle opening, piezoelectric transducer connects measuring device, it is characterized in that, also be provided with the metering module (4) for recording described oil sprayer (5) injection time, metering module (4) connects described measuring device, for regulating the roll-setting gear of described nozzle opening and piezoelectric transducer distance.

2. a kind of fuel injection characteristic measuring system according to claim 1, it is characterized in that, also comprise a high pressure oil pump, high pressure oil pump connection pumps fuel oil and the accumulator making oil pressure stable in order to store high pressure oil pump, and the output circuit of accumulator connects described oil sprayer.

3. a kind of fuel injection characteristic measuring system according to claim 1, is characterized in that, described roll-setting gear is the roll-setting gear (9) driving the motion of described piezoelectric transducer.

4. a kind of fuel injection characteristic measuring system according to claim 1, it is characterized in that, described measuring device is computer terminal (10), computer terminal (10) connects described metering module (4) and manometric module (8) by collecting device (7), and described piezoelectric transducer (6) connects described collecting device (7) by described manometric module (8).

5. the fuel injection characteristic method of measurement of measuring system as claimed in claim 1, it is characterized in that, step is as follows:

1) before measuring: start-stop t interval time measuring piezo sensor output signal ₀, and signal output waveform; By metering module record oil injection duration size T;

2) compare piezo sensor output signal start-stop interval time and oil injection duration size, if two times are unequal, then drive the distance between roll-setting gear adjustment piezoelectric transducer and nozzle opening, until two times are equal, and sensor output waveform is steady;

3) start to measure.