Brushing – scrubbing – and general cleaning – Machines – With air blast or suction
Patent
1990-01-29
1990-11-13
Moore, Chris K.
Brushing, scrubbing, and general cleaning
Machines
With air blast or suction
15344, A47L 928
Patent
active
049692291
DESCRIPTION:
BRIEF SUMMARY
The present invention refers to a battery-operated surface treatment apparatus having a booster function, preferably a vacuum cleaner, according to the preamble of the appending claim 1.
A vacuum cleaner operated from the mains and having a booster function is described in the Swedish patent specification 449 947. In this connection the booster function is to be understood as a temporary increase of the suction force caused by an increase of the speed of the suction fan. For this purpose the supply voltage of the electric motor that drives the suction fan is increased above the level corresponding to the maximum continuously available power for said motor. As a result the operating temperature of the motor increases and may reach unallowable values in case the booster condition is allowed to continue. Hence, a time control device has been provided limiting the period of operation of the booster function.
In the vacuum cleaner referred to an electronic speed control device has been provided by which the booster function can be activated and by which the speed of the electric motor can be varied by variation of the supply voltage. The object of the invention is to permit the use of the booster function also in battery-operated vacuum cleaners or other battery-operated surface treatment apparatus, in particular those not provided with any electronic speed control device. The object will be achieved in a surface treatment apparatus having the features indicated in claim 1. Preferred embodiments have been indicated in the appending sub-claims.
The invention will now be described more in detail in connection with an embodiment with reference to the enclosed drawing showing a circuit diagram for a battery-operated vacuum cleaner.
For the operation of the electric motor 10 of the vacuum cleaner a power supply unit 11 is provided which comprises a suitable number of batteries. The unit 11 has two output terminals, a positive terminal 12 and a negative terminal 13. The terminal voltage is designated "V".
In order to establish a booster function, i.e. a temporary increase of the speed of the motor 10, it is suggested, in accordance with the invention, to increase the supply voltage by introducing a separate battery 14. The terminal voltage of this battery is designated "U" and is considerably lower than the terminal voltage V. With V amounting to about 12 volts U can be about 3.6 volts. The terminals of the separate battery have been designated "+" and "-" and the negative terminal is connected via a conductor 15 to the terminal 12 of the power supply unit. Via a conductor 16 the positive terminal of the battery is connected to a fixed contact 17 of a starting contact device 18 for the booster function. A movable contact 20 is operated by a knob 19 to connect the contact 18 with an additional fixed contact 21 connected to a terminal 22 of a relay 23. The relay has a movable contact 24 and two fixed contacts 25, 26. When the relay is inactivated the movable contact bears on the contact 26 which is connected to the terminal 12. When the relay is activated, the contact 24 will shift to bear on the contact 25, creating a holding circuit for the relay. An additional terminal 27 is provided on the relay and is connected to the negative terminal of the battery 14. The winding 23a of the relay is connected between the relay terminals 22 and 27. A time control device or timer 28 is connected between the terminal 22 on the relay and the movable contact 24. The switching function of the timer is schematically indicated by a contact 29. The relay contact 24 is connected to a terminal 30 which is one of the two terminals 30, 31 of the motor 10. The terminal 31 is connected to the terminal 13 of the power supply unit 11.
The main battery included in the power supply unit 11 suitably comprises a rechargeable battery and in the example a lead accumulator has been chosen. Suitably, the separate battery 14 is also of the rechargeable type, however, in addition it has to be designed so as to take the large current supplied by the main
REFERENCES:
patent: 4535501 (1985-08-01), Hollowell et al.
patent: 4920607 (1990-05-01), Kohn
patent: 4920608 (1990-05-01), Hult et al.
Kilstrom Lars G.
Larsson Anders E. C.
Svanberg Joakim A.
Tuvin Lars G.
Aktiebolaget Electrolux
Moore Chris K.
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