Brushing – scrubbing – and general cleaning – Machines – With air blast or suction
Utility Patent
1999-08-02
2001-01-02
Warden, Sr., Robert J. (Department: 1744)
Brushing, scrubbing, and general cleaning
Machines
With air blast or suction
C015S319000
Utility Patent
active
06167588
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to vacuum cleaners. Particularly, but not exclusively, the invention relates to domestic vacuum cleaners.
BACKGROUND OF THE INVENTION
A domestic vacuum cleaner normally consists of an airflow path having a dirty air inlet at one end and a clean air outlet at the other end. Arranged in the airflow path, normally at or near the clean air outlet, is a fan driven by a motor which draws dirt-laden air into the dirty air inlet. The airflow then passes through dirt and dust separating apparatus to remove dirt and dust particles from the airflow and past the fan and motor before exiting to the atmosphere via the clean air outlet. The passage of the airflow past the motor cools the motor during operation.
Very many vacuum cleaners incorporate filters designed to protect the motor. These filters can be arranged upstream or downstream of the motor. Occasionally, filters are arranged both upstream and downstream of the motor. These filters are in addition to the main dirt and dust separating apparatus of the vacuum cleaner. The dirt and dust separating apparatus will normally consist of either a bag or a cyclonic separator as in U.S. Pat. Nos. 4,571,772; 4,593,429; 4,643,748; 4,826,515; 4,853,008; 4,853,011; 5,062,870; 5,078,761; 5,090,976; 5,145,499 and 5,160,356. Some vacuum cleaners incorporate bleed valves which allow additional air to be bled into the airflow path in the event of a blockage occurring in the airflow path as in WO 94/00046 and WO 98/02080, the disclosure of which is incorporated by reference herein. In some cases, this can help to prevent the motor overheating due to insufficient cooling. However, the filters arranged close to the motor, particularly the pre-motor filter, can also become clogged after extensive use. What very often happens is that the motor includes a thermo-trip which cuts off the motor if it begins to overheat due to insufficient cooling. The user is forced to stop using the cleaner until the motor has cooled down. However, in many cases, the user merely recommences cleaning as soon as possible without addressing the problem of why the motor is overheating. This is because the user is unaware of the specific cause of the motor overheating. Repeated overheating and cut-out of the motor is frustrating to the user. An indication of the cause of the overheating so that the user can address the problem would alleviate some of that frustration.
Provision of an indication to the user of the clogged condition of a dirt-collecting bag is known from U.S. Pat. No. 3,936,904.
Indication to the user that a postmotor filter may require changing is disclosed by DE-A-3712233.
It is an object of the present invention to provide a vacuum cleaner which is easy to operate and which provides an indication to the user that specific action is required to overcome a problem. It is a further object of the present invention to provide a vacuum cleaner which provides an indication to the user that the pre-motor filter is blocked.
SUMMARY OF THE INVENTION
The invention provides a vacuum cleaner as set out in claim
1
. Advantageous features are set out in the subsidiary claims.
The advantage of the invention is that a signal, which warns the user that some action is required, is given when the motor overheats or is likely to overheat due to the pre-motor filter becoming blocked. Blockages upstream of the bleed valve cause air to be bled into the airflow path to maintain sufficient airflow past the motor to prevent overheating. Therefore, the signal is only given when the cause of overheating is different from a blockage occurring upstream of the bleed valve. The signal can be audible or visual, preferably in the form of an illuminated sign or light which is intended to inform the user that the filter or filters located adjacent the motor require to be changed. The signalling means can be made responsive to the actual motor temperature, the ambient temperature within the motor housing or a vacuum pressure change. All three of these characteristics or operating conditions are indicative of a situation in which the motor is likely to overheat.
By providing a warning signal, the user is encouraged to change the filter or filters arranged near the motor. Changing the filter or filters is highly likely to remove the reason for the motor overheating and cutting out. This results in improved performance of the vacuum cleaner and enhanced customer satisfaction.
REFERENCES:
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patent: 4733431 (1988-03-01), Martin
patent: 5141309 (1992-08-01), Wörwag
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patent: 94/00046 (1994-01-01), None
patent: 98/02080 (1998-01-01), None
Morrison & Foerster / LLP
Notetry Limited
Snider Theresa T.
Warden, Sr. Robert J.
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