EP0071308A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Drum speed control system for a washing machine
Assignee: Whirlpool Europe BV
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Filing: 1982-07-22
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Granted: —
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Expires: 2002-07-22
Abstract
Abstract In a washing machine of the type in which the laundry drum speed is controlled to pass relatively slowly through an intermediate laundry distribute speed, in order to cause the articles of laundry load to distribute themselves evenly around the drum, before the drum speed is increased to a spin-dry speed. In the system according to the invention, the distribute speed is maintained for a period while an out of balance test is carried out. Any out of balance causes the speed to change cyclically instead of remaining constant and this change is detected. The drum is then caused to slow down and pass through the intermediate speed again in order to redistribute the laundry load in the drum.
Inventors
- 👤 Siya Vallabh Seth
- 👤 Alexander Hendrik Francis Keulemans
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 19:21
CPC Classifications
D; D06; D06F; D06F37/00; D06F37/30; D06F37/304; H; H02; H02P; H02P25/00; H02P25/02; H02P25/10; H02P25/14; H02P25/145; D06F2103/00; D06F2103/24; D06F2103/26; D06F2105/00; D06F2105/46; D06F2105/48; D06F33/00; D06F33/30; D06F33/48; D06F34/00; D06F34/10; Y; Y02; Y02B; Y02B40/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
220 words
A drum speed control system for a washing machine of the type having a laundry drum which is rotatable about a substantially horizontal axis by an electric motor which is provided with a tachogenerator having an a.c. output signal which is proportional to the speed of the motor and, hence, of the drum; the system being arranged for connection to said motor and tachogenerator to form a speed control loop whereby the motor speed may be automatically brought to a wash speed at which the laundry articles may be washed and then to a higher (spin) speed at which the articles may be at least partially spin-dried, the control system being provided with means for causing the motor to drive the drum relatively slowly through an intermediate speed range to a given (distribute) speed to enable the articles to be distributed evenly around the drum before the control system causes the drum speed to increase to the required spin speed, characterised in that the system includes means for maintaining the distribute speed for a given period, for monitoring the actual speed during this period, and for giving an output signal if the speed changes during this period by more than a predetermined amount, which change in speed is indicative of an unbalanced distribution of the laundry articles around the drum.
Claim 2
Dependent Claim
220 words
A drum speed control system for a washing machine of the type having a laundry drum which is rotatable about a substantially horizontal axis by an electric motor which is provided with a tachogenerator having an a.c. output signal which is proportional to the speed of the motor and, hence, of the drum; the system being arranged for connection to said motor and tachogenerator to form a speed control loop whereby the motor speed may be automatically brought to a wash speed at which the laundry articles may be washed and then to a higher (spin) speed at which the articles may be at least partially spin-dried, the control system being provided with means for causing the motor to drive the drum relatively slowly through an intermediate speed range to a given (distribute) speed to enable the articles to be distributed evenly around the drum before the control system causes the drum speed to increase to the required spin speed, characterised in that the system includes means for maintaining the distribute speed for a given period, for monitoring the actual speed during this period, and for giving an output signal if the speed changes during this period by more than a predetermined amount, which change in speed is indicative of an unbalanced distribution of the laundry articles around the drum.
Claim 3
Dependent Claim
73 words
A control system as claimed in Claim 1, characterised in that the system further includes means responsive to said output signal to cause the motor to reduce the drum speed at least to the wash speed, then to pass through the intermediate speed range to the distribute speed, and then to repeat the monitoring stage to check that the articles are sufficiently evenly distributed around the drum to proceed to the spin speed.
Claim 4
Dependent Claim
62 words
A control system as claimed in either previous Claim, characterised in that the system is so arranged that, if a said output signal is given, the motor is stopped for a time sufficient for the articles to fall to the lowest portion of the drum before the speed is increased again to the wash speed and then through the intermediate speed range.
Claim 5
Dependent Claim
22 words
A control system as claimed in any previous Claim wherein the said predetermined amount is a speed change of more than 5%.
Claim 6
Independent Claim
221 words
A method of controlling the drum speed of a washing machine of the type having a laundry drum which is rotatable about a substantially horizontal axis by a motor which is provided with a tachogenerator having an output signal which is proportional to the speed of the motor and, hence, of the drum, the system being connected to said motor and tachogenerator to form a speed control loop whereby the drum speed may be automatically brought to a wash speed at which the laundry articles may be washed and then to a higher (spin) speed at which the articles may be at least partially spin-dried, the method including the steps of driving the drum relatively slowly from the wash speed through an intermediate speed range to a given (distribution) speed to enable the articles to be distributed relatively evenly around the drum, and subsequently increasing the drum speed to the spin speed, characterised in that the method further includes the steps of maintaining the drum speed at the distribute speed for a given period, monitoring the drum speed during this period, detecting if the drum speed changes during this period by a given amount representative of unevenly distributed articles around the drum, and preventing the drum from increasing its speed to the spin speed if such a speed change is detected.
Claim 7
Independent Claim
221 words
A method of controlling the drum speed of a washing machine of the type having a laundry drum which is rotatable about a substantially horizontal axis by a motor which is provided with a tachogenerator having an output signal which is proportional to the speed of the motor and, hence, of the drum, the system being connected to said motor and tachogenerator to form a speed control loop whereby the drum speed may be automatically brought to a wash speed at which the laundry articles may be washed and then to a higher (spin) speed at which the articles may be at least partially spin-dried, the method including the steps of driving the drum relatively slowly from the wash speed through an intermediate speed range to a given (distribution) speed to enable the articles to be distributed relatively evenly around the drum, and subsequently increasing the drum speed to the spin speed, characterised in that the method further includes the steps of maintaining the drum speed at the distribute speed for a given period, monitoring the drum speed during this period, detecting if the drum speed changes during this period by a given amount representative of unevenly distributed articles around the drum, and preventing the drum from increasing its speed to the spin speed if such a speed change is detected.
Claim 8
Dependent Claim
63 words
A method as claimed in Claim 5, characterised in that it further includes the steps of reducing the drum speed to zero, for a time sufficient for the articles to drop in the drum, if a said change in speed is detected during the monitoring period, increasing the speed through the intermediate speed range again, and then repeating the monitoring and detecting steps.
References Cited (Backward Citations)
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