Textiles: fluid treating apparatus – Machines – Combined
Patent
1997-01-24
1998-09-29
Stinson, Frankie L.
Textiles: fluid treating apparatus
Machines
Combined
210144, 74573R, D06F 3722
Patent
active
058132538
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention refers to an arrangement for balancing of a main mass having an imbalance and rotating about an axis, said balancing being made by means of balancing masses which are relatively freely moveable with respect to the main mass and disposed in at least one closed path symmetrically positioned around the axis, the main mass being adapted to be rotated at speeds both below and above the critical speed and the path being connected with the main mass so as to rotate in synchronism therewith.
In the publications GB-A-1598399 and FR-A-1213067 washing machines are described comprising a washing drum which is rotatable about a horizontal axis. In order to balance the drum when it is accelerated up to a centrifugal speed the drum has been provided at its rear and front end, respectively, with annular closed paths which follow the periphery of the drum, each path containing a plurality of ball-shaped bodies which can move freely in the respective path. In order to dampen the sound from the balls moving in the ball paths and, at the same time, to make the behaviour of the balls become calmer as well as to counteract the tendency of ball self-oscillation the ball paths are filled with oil. In order to prevent, as far as possible, that the balls are activated at washing speed, but, at the same time, achieve that the balls can rapidly change position at speeds above the critical speed the viscosity of the oil has to be properly chosen.
In the washing machines described it can happen that when the washing drum is accelerated to centrifugal speed and when during the following centrifugation phase the drum is driven at that speed the balls in the respective path hit one another causing oscillations of the washing drum in a direction perpendicular to the direction of the axis of rotation. The course can be described as chaotic and instead of a smooth vibrationless movement of the balanced drum additional movement patterns are obtained which complicate the balancing procedure.
Another problem in the washing machines described is that when the drum rotates below the critical speed the balls acting as balancing masses can cooperate with the imbalance in the drum due to the unevenly distributed laundry therein causing very large oscillation amplitudes of the oscillating system to be developed. This leads to great difficulties when the drum is to be accelerated to a centrifugal speed above the critical speed, passing the latter at which the amplitude of the oscillation is at the greatest. The balls which are freely moveable in the closed paths work very well for the purpose of compensating the imbalance in the drum due to the laundry at speeds above the critical speed. However, if allowed to move freely at speeds below the critical speed the balls can cause the disadvantages referred to above.
Another problem is that the relative movement between the balancing weights and the main mass (between the balls and the washing drum including the laundry) can be very large if no measure is taken. This happens when the main mass (the washing drum) and the balancing weights (the balls) are not rotating in synchronism which occurs primarily when the main mass is retarded to standstill while the balancing weights, which cannot be influenced from the outside, continue rotating until the kinetic energy thereof has decayed.
SUMMARY OF THE INVENTION
An object of the invention is to remedy the drawbacks present in the prior art and to provide a balancing arrangement in which the balancing masses are prevented from moving with respect to the main mass when the main mass is rotated at a speed below the critical speed whereas at speeds above the critical speed the balancing masses can be freely positioned in the paths so as to compensate the instantaneous imbalance of the main mass.
DESCRIPTION OF THE DRAWINGS
These and further features of the present invention will be apparent with reference to the accompanying description and drawings, wherein:
FIG. 1 schematically shows a front-load washing ma
REFERENCES:
patent: 1967163 (1934-07-01), Thearle
patent: 3410154 (1968-11-01), Deakin
patent: 4075909 (1978-02-01), Deakin
patent: 4117742 (1978-10-01), Stein
Aktiebolaget Electrolux
Stinson Frankie L.
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