ES2244383T3 - PROCEDURE FOR BALANCING BODIES THAT ROTATE. - Google Patents

Abstract

The method involves using a balance device with ball weights (13) moving freely in a circular track (12) concentric to the drum (2). An imbalance detection unit (6b,c) produces an imbalance signal during rotation or fluctuations in rotation speed. The system is rotated at a speed below its critical rotation speed, or that of its bearing system. The balancing unit is made so that the ball weights are carried in the track at this rotation speed. An evaluation unit (6d) produces the curve of imbalance amount and accelerates the bodies to a rotation speed above the critical speed in the area of the curve minimum or on exceeding a threshold value.

Description

Procedure to balance bodies that they turn.

The invention relates to a method for balance a body subject to rotation by means of a drive regulated, using a balancing device, composed of at less a raceway that rotates with the body, arranged concentrically with respect to its axis of rotation and ring-shaped circular, within which some weights are arranged in such so that they can move freely and using a device imbalance detection, which transforms due deviations to the imbalance of the system composed of the body and the equipment of balanced during rotation and / or its speed oscillations of spin conditioned by the imbalance, in a signal of imbalance, turning the system in a first stage of the procedure for the detection of imbalance with a speed of rotation lower than its critical turning speed or below the critical speed of rotation of your support system and being constituted the balancing equipment in such a way that the weights are dragged by the raceway (s) to this turning speed. The invention relates in particular to a procedure as indicated to balance the drum of a drum washing machine.

A balancing device of the type cited at principle is known for example by EP 0 640 192. In this regard, it is a so-called ball balancer, in which within the raceways are arranged balls that move freely.

The disadvantage of this balancer is that that the work zone essentially depends on the range of frequencies or the speed of rotation chosen for the body at balance. Effectiveness without limitations is only ensured in the frequency range above the maximum resonance frequency (the maximum critical speed of rotation) of the body or its complete support system, consisting of the suspension or fixation or the like, happening between resonances (typical spin speeds) compensates for the balancer conditionally only the imbalances (see for example Kellenberger: Balanced elastic; Springer Verlag; P. 402f, in particular page 408, fig. 20.6).

DE 197 18 321 describes a procedure to balance the drum of a washing machine using a ball balancer: after the washing process, the drum up to a turning speed above the speed of support turn, so that the laundry adheres due to the force centrifuge to the drum wrap and eventually due to the irregular distribution, forms an imbalance. The position of this laundry imbalance is then detected by sensor. The The ball balancer's raceway is filled with a viscous damping element (eg silicone oil), whose viscosity is sized in such a way that the balls, in the range of rotation speeds of imbalance detection, roll still freely. Then it accelerates so strongly the drum in a certain position, previously calculated, of the imbalance and the balls, which the balls are torn from the element shock absorber. The imbalance and the center of gravity of the balls are opposed and with that, that at go through the critical speed of rotation (resonance frequency) is compensate The drawback of this procedure is the strong temperature dependence of the viscosity of the element shock absorber. Particularly when using balancers of balls in washing machines in which the temperature of the laundry and with it also the temperature of the damping element can range between 20ºC and 100ºC, the fulfillment of a prescription precise behavior in terms of friction is only possible With very expensive oils. In addition, the phase in which balls and the laundry imbalance are opposed, it is only very short for each turn of the drum and errors may occur in the unbalance position or position detection Exactly of the balls, that when passing the drum through the speed zone Critical turn can no longer be considered or corrected. It arrives then at very strong deviations from the group that oscillates.

From DE 198 57 663 a washing machine is known in which the raceway is filled with a viscous damping element, which carries the balls with it at the washing speed. In this way, viscosity sizing is not critical. By detection by sensor of the fixed imbalance B formed by the balls and the subsequent rapid acceleration from a position in which the balls are in a predetermined angular area, it must be achieved that an imbalance of the opposite laundry A is specifically constituted at fixed imbalance B. The position of both imbalances with each other can then be varied even by brief braking or acceleration pulses, whereby the spin acceleration continues at that time and the spin speed increases beyond the spin speed critical, when both imbalances are opposed and compensated in the best possible way. Since the variation of the position of the balls takes place only randomly, numerous braking and acceleration processes with subsequent imbalance detection may be necessary to achieve a satisfactory distribution of the imbalances, resulting in very long waiting times. In addition, due to the braking impulses, the motor, drive belts and bearings are loaded.
drum.

The invention thus formulates the problem of giving know a procedure to balance a rotating body of the type quoted at the beginning in which safely and in a while as short as possible an imbalance compensation is achieved before passing through the zone of the critical speed of rotation or its resonance frequencies.

In the context of the invention, this problem through a procedure with the particularities of the claim 1. Advantageous improvements and improvements of the invention result from the following claims high schools.

The advantage that can be achieved through procedure configured according to the invention results from the evaluation of frequency compensation processes relatively low, so that the instant of compensation of the imbalance can be previously determined very accurately and with this a step through the critical speed of rotation is possible with the minimal imbalance

An exemplary embodiment of the invention is represented simply schematically in the drawings and it will describe more in detail below. It shows in

Figure 1 asymmetric speed evolution of rotation of a body that rotates with axis of horizontal rotation and regulated drive

Figure 2 the imbalance signal of the total imbalance consisting of laundry and weights, throughout the weather

Figure 3 the envelope curve of the value of the imbalance signal

Figure 4 a schematic drawing of a machine washing machine to perform a balanced balancing procedure according to the invention

Figure 5 a speed profile of spin-time in a washing machine like the indicated.

The invention is based on the following knowledge:

In bodies that rotate with horizontal axis of rotation or approximately horizontal, which are affected by a imbalance, the speed of rotation varies periodically with the imbalance position. If the body has a drive regulated, then certainly the regulation tries to compensate for these variations, but this then results in oscillations not sinusoidal in the speed signal (see figure 1).

Therefore there is no ideal circular motion of the body that turns. For such bodies with balancing equipment dynamic according to the general concept of claim 1 a check, therefore, only the fundamentals govern theorists (see for example Kellenberger: Elastic balanced; Springer publishing house; P. 402f), which indicate that they result between center of gravity of the compensation weights and the center of gravity of the imbalance a constant phase offset, which in the range of subcritical rotation speeds is 0º, in the range of Critical turning speeds is 90º and in the supercritical range it is 180º.

In the subcritical range the centrifugal forces are reduced due to low turning speed. Thus the perimeter direction forces of the track of rolling, which due to oscillations due to regulation They act on compensation weights. It is then a sliding between the weights and the raceway and in consequence also between weights and body imbalance That has been assumed to be in a fixed place. Because of this "emigrate" the position of the center of gravity of the masses of compensation permanently with reference to the center of gravity of body imbalance.

In the range of supercritical turning speeds high centrifugal forces act on the weights and give rise to these to a high friction by adhesion in the track of rolling The frictional force caused by the friction of adhesion acts as opposed to the forces in the direction perimeter of the raceway, which are formed due to the oscillations caused by regulation. That is why they assume the weights constant positions, resulting between the center of gravity of the weights and the center of gravity of the imbalance a phase offset 180º constant. The weights then compensate for imbalance.

The passage through the range of turning speeds criticism usually takes place very quickly and can considered as a transition between the two phases described above.

In the subcritical zone, the slippage between weights and the imbalance of the body causes them to overlap two signs of sinusoidal imbalance (also weights mean an imbalance when its distribution on the track of rolling is not uniform) with different frequencies and give rise to a derives from the total imbalance signal (see figure 2). The cause resides then that the imbalance of the body circulates with the speed of rotation of the body and imbalance of the balls, due to when sliding, it has a slightly lower turning speed. Since the difference in turning speeds is only very Small, drift has a low frequency. The same is in the Example described below of a washing machine drum, for a drum rotation speed of 100 min -1, of about 60 seconds. In the minimum of the drift are the imbalance of the body and center of gravity of the opposing balls, and it compensate each other.

In bodies with vertical axis of rotation can achieve the evolution of the non-sinusoidal speed of rotation by a specific regulation or control, in which from the drive positive acceleration pulses are printed or negative to the rotating system. These impulses are emitted, so advantageous, so that they act periodically on the system. By such specific impulses you can (even in bodies with horizontal axis of rotation) influence the duration of the drift.

The procedure is described below. configured according to the invention for use in a machine drum washer:

Figure 4 shows based on a drawing schematic the essential parts for the invention in a machine washing machine as indicated. It has a container for laundry (1), in which a drum (2) to house the laundry (3) is supported so that it can rotate. The drum drive (2) takes place by means of a motor (4), and the transmission of force to through a V-belt (5). In this regard, the speed of motor rotation can be adjusted in the known manner by means of a motor regulator (6a) integrated in the control by microprocessor (6) of the washing machine, depending on the program and status.

The laundry container (1) is suspended of springs (7) oscillatingly in the housing (8) and rests, to dampen these oscillations, in the lower zone, through shock absorbers (9) against the floor of the housing. For more oscillation attenuation, are arranged in the container for laundry (1) additional weights (11), so it does not it hits the housing (8) when it crosses the critical area of the turning speed.

On the drum cover (in the previous area of the drum, not shown) and eventually also on the floor of the drum (in the rear area of the drum, not shown) is used as a balancing system a so-called ball balancer. In its raceways (12) individual balls (13) are arranged as weights and can move freely in the perimeter direction of the drum. To ensure maximum compensation, each raceway (12) must be filled in very compressed packaging, in an area prescribed angle, with balls. By determining the size and of the amount of the balls (13), an imbalance can be generated in the order of magnitude of its total weight and with it also compensate In washing machine drums (2) supported by a side is enough a ball balancer on the drum cover. The imbalance masses on the back of the drum (2) they have only a small lever arm and at the front of the drum (2) a large lever arm. The imbalance forces are retransmitted by the drum (2) through the bearing (no represented) to the oscillating unit (laundry container (1), springs (7), shock absorbers (9)). When the drum torque (2) is large, increases the total load of the oscillating unit. The load must therefore be attributed to the torque and thus to the product of imbalance, acceleration and lever arm mass. It is therefore sufficient to balance the masses of imbalance with the large lever arm in the front half of the drum.

Since when the axis of rotation is horizontal the force of gravity acting on the balls (13) is exceeded from a desired rotation speed and balls (13) are dragged along the raceway (12), the same with a viscous damping element (14), using advantageous way oil. Without this damping element (14) the balls (13) would be subjected only to rolling friction and with it they would roll in the lower part of the raceway (12), without developing its compensatory effect. An oil is used with a very high viscosity, which ensures that the balls (13) are already dragged at wash spin speeds of about 50 min -1. Then they generate in the subcritical zone a fixed imbalance B that rotates with the drum. After passing through the Critical range of turning speeds are distributed, to compensate, totally or at least partially, the imbalance of laundry B which results from an irregular distribution of the laundry.

A path sensor (15), arranged parallel to a shock absorber (9) or integrated into it, calculate the lowering of the laundry container, which is a function of weight, and transmits the corresponding signal to a computer circuit (6B) integrated into the microprocessor control (6). Centrifugal force that acts on the imbalances A and B or on the total imbalance C resulting from them, overlaps vectorly to the force of gravity, bringing the signal of weight is subject to periodic oscillations that depend on imbalance, which must be included to calculate the imbalance by the computer circuit (6B). Instead of trajectory sensor (14) can be used for example a sensor acceleration known from DE 195 22 393 for the detection of imbalance. Additionally or alternatively to this method you can calculate another computer circuit (6c) the imbalance by evaluation of the oscillations of a signal that depends on the speed of rotation (motor current, slip) or of the own turning speed (with a tachogenerator (15)).

An evaluation circuit (6d) integrated in the processor control prepares the imbalance signal of the circuit or circuitry of the computer (6b, c) measured during the drum rotation so that only the curve is calculated envelope of the imbalance signal value and is evaluated for continue with the motor regulation (see figure 3).

The procedure corresponding to the invention to balance the drum of a washing machine is represented in Figure 5 based on a velocity profile of turn-time and works as follows:

After the washing process, it takes place First, an evacuation by pumping the laundry from the wash bowl (1). Then the acceleration starts of centrifuge. It starts with the boot up to a speed of measurement n_ {Mess1} above the speed of turn of support of the laundry n_ {A}, but below the value more low resonance speed n_ {R1}. For the drain prior to the laundry and for a more precise detection of imbalance, can rise directly after the distribution of the laundry in the drum wrap (2c) the speed of rotation for a brief moment until the drain turning speed n_ {E}, but nevertheless the value must always be less than lowest value of the resonance rotation speed n_ {R1}. The turning speed is then lowered to the speed of measurement turn n_ {Mess1}.

After reaching again the turning speed of measure n_ {Mess1} total imbalance detection takes place C through the computer circuits (6b, c). From the signal of imbalance, the evaluation circuit evaluates the curve envelope of the signal value, to start at the minimum of Drift passes through resonance. For this the acceleration continues spin and the drum (2) accelerates to a speed of spin above the resonance frequency n_ {R1}.

Drift frequency (see figure 2) can be reduced by strong periodic acceleration impulses, with what the duration until the passage by the minimum of drift is shortened in the time.

In an improved extension of the procedure, choose a start instant for spin acceleration found before reaching the minimum drift. Since the balls (13), due to sliding, continue to move until the passage through the resonance rotation speeds and the own acceleration towards spin spin speed increases strongly sliding can be achieved in this way that in the moment of the passage through the critical turning speed a minimum imbalance and with it the deviation of the unit oscillatory be kept small.

For this, the first minimum of the curve is detected envelope and this value is memorized. Then wait for the circuit evaluator (6d) until the total imbalance reaches below a threshold that depends on the first minimum, the total load, the type wash and acceleration procedure, threshold that is higher to the minimum first detected. Then the spin acceleration proper through the resonance rotation speeds n_ {Ri}.

A faster alternative to this is the calculation one instant start for spin acceleration through the evaluation circuit (6d) found before first minimum of drift. This instant depends on the service point (load status) of the washing machine and can be calculated using an algorithm from the envelope curve. The optimal point is is in the area of the turning point of the envelope curve, in each case before reaching the first minimum.

Another improvement is to consciously generate laundry imbalances in terms of magnitude and / or position. The Procedures hitherto known for laundry support pursue the goal of positioning it in the most possible uniform in the drum wrap (2c). Since both the type of wash as well as the amount of laundry can presuppose as known by attracting different parameters (e.g. suction times, lowering of the container washing, etc.), can be generated by a speed pulse of I turn a laundry imbalance that corresponds to the ball compensation capacity (13). In this case, in the minimum drift almost completely compensates for the entire imbalance of the laundry by means of the conglomerate of balls. Through the specific positioning of the imbalance of the laundry in relation to to the conglomerate of balls, the Time to find the minimum.

To achieve another optimization, they can be repeated these algorithms also between the different resonance zones n_ {Ri}. By choosing the acceleration profile properly, you can take advantage of the equilibrium zone n_ {messi} that found between the different resonance frequencies n_ {Ri} also to continue minimizing the imbalance.

Claims (8)

1. Procedure to balance a body, which by means of a regulated drive it is put into rotation, using a balancing equipment, consisting of at least one track of rolling (12) circulating with the body, concentrically arranged with its axis of rotation and in the form of a circular ring, within the which weights (13) are arranged so that they can move freely and using a device to detect the imbalance (6b, c), which transforms the deviations due to system imbalance composed of the body and equipment balanced during rotation and / or its speed oscillations of turn due to imbalance in an imbalance signal, turning the system in a first stage of the procedure for detection of imbalance with a turning speed below its critical turning speed or below the turning speed critical of your support system and the equipment being configured balanced in such a way that for this speed of rotation the weights (13) are dragged along the raceway (s) (12), characterized in that an evaluation circuit (6d) calculates the envelope curve of the value of the imbalance signal and in the zone of its minimum or when it becomes lower than a limit value, accelerates the body to a turning speed above its turning speed Critical or critical turning speed of your support system. 2. Procedure to balance a body that rotates according to claim 1, characterized in that the evaluation circuit, taking into account the service parameters, calculates a value to start the acceleration up to a speed above the critical speed of the body or its support system, the value being found just before reaching the first minimum of the envelope curve of the imbalance signal value. 3. Procedure to balance a body that
rotates according to claim 1 or 2, characterized in that the adjusting elements of the speed of rotation or of regulation acting on the drive emit at least one positive or negative acceleration pulse to the system during a complete turn of the system. 4. Procedure to balance a body that rotates according to claim 3, characterized in that the positive or negative acceleration impulses act periodically on the system. 5. Procedure to balance a body that rotates around an approximately horizontal axis of rotation according to the minus one of claims 1 to 4, characterized by the use of an element disposed in the raceway (s) (12) to increase the rolling friction of the weights or the flow resistance of the raceway (s). 6. Procedure to balance a body that rotates around an approximately horizontal axis of rotation according to the claim 5, characterized in that the element for raising the flow resistance of the raceway (s) (12) is composed of a viscous damping means (14), whose viscosity is achieved in such a way that the weights (13) they are dragged in the range of turning speeds in which the imbalance detection is performed. 7. Procedure for drum balancing (2) of a drum washing machine according to at least one of the claims 1 to 6, characterized in that the detection of the imbalance is carried out above a turning speed in which the laundry, due to centrifugal acceleration, is supported by the drum wrap (2c). 8. Procedure for drum balancing (2) according to claim 7, It characterized in that an unbalance of the laundry predetermined magnitude and / or position is generated.