CN1760429A - Method for testing eccentric degree of drum - Google Patents

Abstract

The present invention adopts a short-periodic power-on and power-off method of motor and collects the rotating speed change due to eccentricity of the drum which is rotated for a turn at 72-85 RPM to make detection of drum eccentricity. Its detection result is reliable and accurate. Said invention is applicable to detection of material eccentricity in drum washing machine and similar centrifugal dewatering equipment.

Description

Method for testing eccentric degree of drum

Affiliated technical field

The present invention relates to the detection method of material eccentric degree in the cylinder of a kind of tumbling-box washing machine and similar centrifugal dehumidifier.

Background technology

Tumbling-box washing machine, Water Extraction Machinery and similar devices, its common feature is: near cylindrical, the container of cydariform a---cylinder that rotates around horizontal middle spindle is arranged, the content material (as clothing etc.), by around its rotation at a high speed, realize functions such as centrifugal dehydration.The rotating shaft of the rotary container of the equipment that also has is out-of-level, and horizontal by a less angle, usually less than 30 °, this situation belongs to level of approximation, and the situation of it and rotating shaft level is as broad as long in this patent, is considered as being equal to.Its common difficulty is: because gravity and container are asymmetric relation, material wherein is easy to secundly, is difficult for being evenly distributed, and produces bigger eccentric force when rotating at a high speed, produces strong vibration, noise.

The Chinese patent application 03103407.1 of LG Electronics Inc. is to measure the fluctuations of speed at two above speed stages for the patent of representative provides a series of methods of measuring off-centre, measures off-centre by relatively fluctuation size, and Measuring Time is long.The Chinese patent application CN03129726.9 of Lejin Electronic and Electric Appliance Co Ltd (Tianjin) is then by open loop control motor, and by measuring acceleration analysis off-centre, because motor armature-reaction in the acceleration process changes, moment has fluctuation, can influence measurement.

Summary of the invention

The purpose of this invention is to provide a kind of sensitivity, reliably, method for testing eccentric degree of drum fast.

The method that eccentric degree provided by the invention detects is: with certain rotating speed---detecting rotating speed---more than swing roller 2 circles, with the fixing cycle motor is carried out switch control therebetween, each cycle is when beginning, if drum rotation speed is lower than the detection rotating speed, electrical power one-period then, otherwise outage one-period; Write down the switch situation and the rotating speed in each cycle simultaneously.

The principle of above-mentioned eccentricity detecting is actually measures that gravitional force discharges the degree that causes that drum rotation speed increases when eccentric, and when eccentric center material rose, gravitional force increased, and cylinder slows down, and when being lower than the detection rotating speed, electrical power one-period is to keep drum rotation speed; When eccentric center material descended, gravitional force reduced, and cylinder quickens, and motor is with continuous a plurality of cycle outages.Off-centre is serious more, and gravitional force is big more, and the rotating speed increase is big more.According on off state sequence that is write down and rotating speed sequence, just can judge the size of eccentric degree.

Since motor outage during rotating speed increases, the influence of having avoided armature-reaction to change, testing result sensitivity, reliable; Because only need complete rising of record, decline process, required time is short.Obviously, be at random owing to measure the position of off-centre when beginning, need the data of record 2 circles, could guarantee complete rising of record, decline process.

The cycle of power on/off must lack, and is less than 30 milliseconds usually, and maximum is no more than 50 milliseconds, otherwise increases too much at an energising cycle medium speed, and measurement point is few simultaneously, influences measurement effect.To alternating current generator, get the cycle or the half period of alternating current usually.

Detect rotating speed and be not less than 1.2 times that separate rotating speed, common (preferably) is not higher than 1.42 times.Detect better effect with lower rotating speed, can increase detection sensitivity.The principle of eccentricity detecting is that gravitional force discharges the degree that causes that drum rotation speed increases when measuring off-centre, and incremental speed is big more, detects sensitive more.If eccentric gravitional force is E, drum rotation speed is respectively ω before and after discharging ₁, ω ₂, the cylinder rotary inertia is I, according to the conservation of energy:

$\frac{1}{2}I{\mathrm{\ω}}_2^2=\frac{1}{2}I{\mathrm{\ω}}_1^2+E\⇒{\mathrm{\ω}}_2=\sqrt{{\mathrm{\ω}}_1^2+2E/I}$

$\mathrm{\Δ\ω}={\mathrm{\ω}}_2-{\mathrm{\ω}}_1={\mathrm{\ω}}_1\sqrt{1+\frac{2E}{I{\mathrm{\ω}}_1^2}}-{\mathrm{\ω}}_1\≈\frac{E}{I{\mathrm{\ω}}_1}$

Promptly under first approximation, incremental speed and initial speed ω ₁Be inversely proportional to, rotating speed is low more, and sensitivity is high more.The present invention will detect rotating speed in preferable case and be controlled at 72～85 rev/mins (to cylinders of radius about 0.25), and will be highly sensitive in prior art.

Above-mentioned separation rotational speed N _FBe a characteristic quantity of cylinder, it is defined as: $N_F=\frac{60}{2\mathrm{\&pi;}}\sqrt{g/{\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="A20051010613500061.png,A20051010613500062.png"\; state="\{\{state\}\}">R</figure-callout>}}_0},$ Unit is rev/min (RPM, a habitual engineering unit).Wherein: R ₀Be the inner wall of rotary drum radius, g is an acceleration of gravity, and π is a pi.

The physical meaning of separating rotating speed is: when rotating speed when separating rotating speed, material will be because of gravity fall and roller separation on the top; Otherwise, then do not separate, even at the peak of cylinder.In fact, rotating speed need be not less than 1.2 times and separate rotating speed, and material could effectively be fixed on inner wall of rotary drum.

For family expenses roller washing machine commonly used, R ₀0.25 meter of ≈ separates rotational speed N _F60 rev/mins of ≈.At this moment, 1.2 times of separation rotating speeds are about 72 rev/mins, and 1.42 times are about 85 rev/mins.Usually, eccentricity detecting is to carry out after washing machine carries out the operation of material homogenising, terminal point rotating speed during the homogenising EO can be made as detection rotating speed and this terminal point rotating speed identically usually just between 72～85RPM, carries out eccentricity detecting when the homogenising EO at once.

According to the on off sequence and the velocity series of record, can judge the eccentric degree of cylinder, and a plurality of eccentric degree grades of setting up eccentric degree to increase successively from 0 grade to the K level, 0 grade of off-centre is for eccentric, K level eccentric degree maximum, wherein K is a natural number, K 〉=2.

The method of judging has multiple, and a kind of simple method is to detect the maximum of rotating speed, but the detection of this single-point is subject to the interfering signal influence.Replacing maximum with mean value, is jamproof effective ways, better with the on off sequence fiting effect.Be specially: when continuously the outage number of times is all the time less than certain number of times between detection period, judge 0 grade of off-centre of cylinder, promptly not eccentric; During more than or equal to above-mentioned number of times, the speed between turnoff time is added up, itself and obtain mean value divided by number of times, judge eccentric degree according to the size of mean value, mean value large eccentricity more is big more.

The another kind of similar method better effects if based on waveform recognition is specially: when the outage number of times is all the time less than certain number of times continuously between detection period, judge 0 grade of off-centre of cylinder, and promptly not eccentric; Otherwise preliminary judgement cylinder off-centre is further judged eccentric degree according to the rotating speed sequence of this group sampled point: set K-1 greater than the terminal point rotational speed N _YZAnd the judgement rotational speed N that increases progressively _P2, N _P3..., N _PkAnd K-1 judgement number of times C ₂, C ₃..., C _k, judge from high in the end: in this rotating speed sequence greater than judging rotational speed N _PiNumber of times greater than judging number of times C _i, be judged to be i level off-centre; All the other are 1 grade of off-centre.Wherein i is a natural number, i≤K.

Method provided by the invention, since motor outage during rotating speed increases, the influence of having avoided armature-reaction to change, and testing result is reliable; Adopt low-speed detection, improved sensitivity; Because only need complete rising of record, decline process, required time is short.

Description of drawings

Fig. 1 is a typical waveform without acceptance of persons

Fig. 2 is the typical waveform of slight eccentricity

Fig. 3 is serious eccentric typical waveform

The specific embodiment

Below in conjunction with accompanying drawing,, further specify the eccentric detection method that the present invention proposes by embodiment.

The preferred embodiment 1 that the present invention proposes is the example of waveform recognition algorithm, describes in detail below in conjunction with accompanying drawing 1,2,3.0.25 meter of the radius of this routine intermediate roll, the simple flow process of laundry machine dehydration is as follows:

(1) carry out homogenising operation, during end drum rotation speed be 83 (rev/min).

(2) with 83 (rev/min) serve as to detect rotating speed, carry out eccentric degree and detect

(3) according to the eccentric degree that detects, dehydration or homogenising operation are again led in decision.

Step (two) is exactly an eccentricity detecting, and the power on/off cycle that this example adopts is 20 milliseconds of cycles of civilian 50Hz alternating current, and promptly per 20 milliseconds are detected a drum rotation speed, if this moment, rotating speed was lower than 83RPM, then electrical power is 20 milliseconds, and more than or equal to 83RPM, then the motor outage is 20 milliseconds as if rotating speed.Write down each power on/off situation and rotating speed simultaneously.

1,2,3 o'clock actual typical data situations that record of accompanying drawing.Figure middle part curve is represented rotating speed, and the little triangle of lower curve is represented electrical power, and no triangle is represented the motor outage, and ordinate is a rotating speed, and abscissa is to measure number of times.

According to control law, in a single day rotating speed is lower than 83 rev/mins just switches on one-period, and the actual average rotating speed is about 85～86 rev/mins, and cylinder revolves the measurement number of times that turns around and is about 34～35 times.

Fig. 1 is a typical waveform without acceptance of persons, can find out that therefrom cycle of electrical power basic evenly distributes, and the periodicity of outage is about 7～9 times continuously, less than the measurement number of times of cylinder rotation half-turn 17 times.Fluctuation of speed amplitude is also even substantially.

Fig. 2 is slight eccentric typical waveform, can find out that the period profile of electrical power is inhomogeneous, and the periodicity of outage is about 16～23 times continuously, near or surpass the measurement number of times 17 times of cylinder rotation half-turn.But fluctuation of speed amplitude is also not high between turnoff time.

Fig. 3 is serious eccentric typical waveform, not only continuously the periodicity of outage near or surpass 17 times, and rotating speed obviously increases considerably between turnoff time.Therefore, rotating speed increase situation between turnoff time is classified, can determine eccentric degree.

The actual decision algorithm of this example is: the periodicity that cuts off the power supply continuously during the whole measurement all is no more than 15 times, is 0 grade of off-centre (not eccentric); Surpass 15 times, preliminary judgement has off-centre.Further judge according to the speed of this group time excess again: if greater than the number of times of 90RPM greater than 12 times, be 4 grades of off-centre; Greater than 12 times, is 3 grades of off-centre greater than the number of times of 89RPM; Rotating speed greater than 11 times, is 2 grades of off-centre greater than the number of times of 87RPM; All the other 1 grade of off-centre.Obviously, 1 grade of off-centre be actually rotating speed greater than the number of times of 87RPM less than 11 times.

The preferred embodiment 2 that proposes according to the present invention, roughly the same with embodiment 1, difference is eccentric judgement mean value method.The radius of this routine intermediate roll also is 0.25 meter, and the simple dewatering process flow of washing machine is basic identical, as follows:

(1) carry out homogenising operation, during end drum rotation speed be 75 (rev/min).

(2) with 75 (rev/min) serve as to detect rotating speed, carry out eccentric degree and detect

(3) according to the eccentric degree that detects, dehydration or homogenising operation are again led in decision.

Step (two) is exactly an eccentricity detecting, and the power on/off cycle of employing is half 10 milliseconds of cycle of civilian 50Hz alternating current, and promptly per 10 milliseconds are detected a drum rotation speed, if this moment, rotating speed was lower than 75RPM, then electrical power is 10 milliseconds, and more than or equal to 75RPM, then the motor outage is 10 milliseconds as if rotating speed.Write down each power on/off situation and rotating speed simultaneously.The typical data situation is similar to accompanying drawing 1,2,3, and only rotating speed is different with number of times.

According to control law, in a single day rotating speed is lower than 75 rev/mins just switches on one-period, and the actual average rotating speed is about 77～79 rev/mins, and cylinder revolves the measurement number of times that turns around and is about 76～78 times.

Eccentricity detecting adopts mean value method, is specially: when the outage number of times is all the time less than 36 times continuously between detection period, judge 0 grade of off-centre of cylinder, and promptly not eccentric; During more than or equal to 36 times, the speed between turnoff time is added up, itself and obtain mean value divided by number of times, according to the size of mean value, judge eccentric degree from high to low: mean value is 4 grades greater than 84rpm, is 3 grades greater than 82rpm, greater than 79rpm is 2 grades, is 1 grade smaller or equal to 79rpm.The rotating speed that detects energising in this example is 75rpm, and average speed is not just at 77～79rpm when eccentric, and therefore gravitional force just overcomes the frictional dissipation that cylinder rotates basically in 1 grade of off-centre, rotates about half-turn under the motor powering-off state.This also can be used as the principle of classification.

More than in each example, the radius of all getting cylinder is 0.25 meter, for the cylinder of other radiuses, is not difficult to calculate according to aforementioned formula.

Obviously, same invention can have numerous embodiments, and the present invention is not limited only to above embodiment, and those of ordinary skill can be constructed other embodiment according to thought of the present invention and method; Also be not limited only to tumbling-box washing machine, also be applicable to similar centrifugal dehumidifier.This can not think to have exceeded scope of the present invention.

Claims (7)

1. eccentric detection method that is used for index drum formula washing machine and similar centrifugal dehumidifier dehydration, dehydration under it is made of steps such as carrying out homogenising operation, eccentricity detecting, the main dehydrating operations of high speed successively, its host's roller washing machine or centrifugal dehumidifier comprise parts such as cylinder, controller, drive motors and corresponding speed regulator, revolution detector, eccentric degree detector, it is characterized in that:

With detect rotating speed swing roller 2 circles or more than, with the fixing cycle motor is carried out switch control therebetween, each cycle is when beginning, if drum rotation speed is lower than the detection rotating speed, electrical power one-period then, otherwise outage one-period; Write down the switch situation and the rotating speed in each cycle simultaneously

Described detection rotating speed is not less than 1.2 times of roller separation rotating speeds, and the described fixing cycle is not more than 50 milliseconds.

2. according to the described method of claim 1, it is characterized in that:

The described fixing cycle is not more than 30 milliseconds.

3. according to the described method of claim 1, it is characterized in that:

The cycle of described Zhou Ding equals the cycle of the alternating current of drive motors.

4. according to the described method of claim 1, it is characterized in that:

The described fixing cycle equals half of cycle of the alternating current of drive motors.

5. according to claim 1,2,3 or 4 described methods, it is characterized in that:

Described detection rotating speed separates the range of speeds at 1.2～1.42 times.

6. according to the described method of claim 5, it is characterized in that:

According to the on off sequence and the rotating speed sequence of record, judge the eccentric degree of cylinder: when the outage number of times is all the time less than certain number of times continuously between detection period, judge that cylinder is not eccentric; Otherwise, judge eccentric degree according to this size of organizing the mean value of continuous power down sequence rotating speed, mean value large eccentricity more is big more.

7. according to the described method of claim 5, it is characterized in that:

According to the on off sequence and the rotating speed sequence of record, judge the eccentric degree of cylinder, K eccentric degree grade setting up the eccentric degree from 0 grade to the K level to increase successively, 0 grade of off-centre be for eccentric, K level eccentric degree maximum

When continuously the outage number of times is all the time less than certain number of times between detection period, judge 0 grade of off-centre of cylinder, promptly not eccentric; Otherwise, preliminary judgement cylinder off-centre, further judge eccentric degree according to this rotating speed sequence of organizing between continuous turnoff time:

Set K-1 greater than the terminal point rotational speed N _YZAnd the judgement rotational speed N that increases progressively _P2, N _P3..., N _PkAnd K-1 judgement number of times C ₂, C ₃..., C _k, judge from high in the end: in this rotating speed sequence greater than judging rotational speed N _PiNumber of times greater than judging number of times C _i, be judged to be i level off-centre; All the other are 1 grade of off-centre

Wherein i, K are natural number, i≤K, K 〉=2.

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