Cooling arrangement for power components in a vacuum cleaner

Abstract: This invention relates to a vacuum cleaner comprising a housing (10) which is provided with an electric circuit, a motor-fan unit (14) and a chamber (11) for a dust container (12). The chamber is provided with an opening (16) through which the dust container can be removed from the chamber, said opening normally being closed by a cover (17). The cover (17) is provided with a heat transmitting surface which is thermally connected with at least one heat generating power component (42) in the cover.

Description: This invention relates to a vacuum cleaner comprising a housing which is provided with; an electric circuit having at least one heat generating power component such as a triac or a start-up resistor; a motor-fan unit for drawing air through a dust container chamber the chamber being provided with an opening through which the dust container can be removed from the chamber, said opening normally being closed by a cover. The electric circuit for vacuum cleaners of the type mentioned above usually comprises different types of heat generating power components for instance start-up resistors or triacs to control the speed of the motor. These power components which generate a lot of heat are usually placed in close vicinity of and after the motor-fan unit as seen in the flow direction. Sometimes integrated circuit boards are used on which the components are collected which facilitates assembly - see for instance EP 365797. Such a disposal means that the electric components will not be cooled in an efficient way since the air flow is also used to cool the electric motor of the motor-fan unit and hence will be heated up before it reaches the electric components. Since the power of electric motors for vacuum cleaners has been gradually increased it has been necessary to enlarge the area of the cooling surfaces for the power components in order to get efficient cooling as well as to use components which are highly specified and this has increases the costs. In order to effectively cool a power component for a vacuum cleaner it has also been suggested, see DE-A-4212643, to put the component in the cold air flow on the inlet side of the fan and by means of an electric conductor connect the component with an integrated circuit board which is placed after the fan seen in the air flow direction. A similar arrangement is also described in SE 349742 in which the heat sensitive components are placed on a heat transmitting plate close to the dust container. The disadvantages of these arrangements are however that assembling the components and connecting them to the other electric equipment is complicated. It has also been suggested, see JP 63-283671, to use optic sensors for vacuum cleaners in order to sense the type of dust bag being used in the vacuum cleaner and in dependency of this type control the motor of the vacuum cleaner so that it works under optimal conditions. The sensor is arranged in the cover belonging to the chamber in which the dust bag is placed. This arrangement does however not relate to a power component but to a single electric component which has been placed in a suitable position in the vacuum cleaner solely in order to read the type of bag being used. FR-A-2411452 describes a vacuum cleaner that is provided with a temperature sensor for the motor. The purpose of this invention is to achieve an arrangement which gives an effective cooling of the heat generating components and hence to make it possible to use cheap components and which also facilitates assembly since the electric components can be mounted on the cover as a seperate unit before the cover is mounted in the vacuum cleaner. The cover is easily accessible and has such a position in the vacuum cleaner that it can be connected to the other electric components by means of a minimal amount of conductors. Since the cover is placed close to or comprises the sleeve to which the hose of the vacuum cleaner is connected also the establishment of the electric connection between a remote control placed at the tube handle of the vacuum cleaner and the motor of the vacuum cleaner is facilitated. The arrangement also has the advantage that the same cover can be provided with different electric components for different types of vacuum cleaners. By means of the suggested arrangement the space behind the motor-fan unit which is normally occupied by electric equipment instead can be used for filtration and sound reduction. Said advantages are achieved by means of a device having the characteristics mentioned in the claims. An embodiment of the invention will now be described with reference to the accompanying drawings in which Fig. 1 is a vertical section through a vacuum cleaner which is provided with a device according to the invention whereas Fig. 2 is a vertical section in a larger scale through a part of the vacuum cleaner. The vacuum cleaner comprises a housing 10 which encloses a chamber 11 for a dust container 12, which preferably is an air pervious paper bag. The chamber 11 communicates via a filter 13 with the inlet side of a motor-fan unit 14 arranged in the rear part 15 of the vacuum cleaner. The chamber 11 has an opening 16 which is normally closed by a cover 17 and this cover is provided with a bent sleeve 18 to which the end part 19 of a flexible hose 20 can be connected. Near the sleeve 18 there is a holder 21 for a collar 22 which is a part of the dust container. The holder is pivotally supported at 23 and has an opening 24 through which the end of the sleeve 18 protrudes when the cover is in its closed position. The cover 17 is supported by a hinge 25 and is sealed from the edges of the opening 16 by means of a sealing 26. The cover can by means of a locking mechanism, not shown, be fixed in the closed position as shown in Fig. 1. The cover 17 which preferably is of plastics has a hollow structure and comprises an outer and an inner wall part 27 and 28 resp. Between the wall parts 27 and 28 there is a integrated circuit board 29 resting on supports 30 extending upwards from the inner wall part 28. The integrated circuit bord 29 is a part of the electric circuit of the vacuum cleaner and is provided with different electrical components such as pressure sensing means, switches, indicating means and power componenets for operating and controlling the vacuum cleaner. The circuit of the integrated circuit board 29 or the components are connected to contact means 31 and 32. The contact means 31 is so placed that when the end part 19 of the hose 20 is fixed to the sleeve 18 the contact means 31 is in engagement with a plug 33 which via a conductor, not shown, is electrically connected to a remote control means arranged on the tube handle to which the hose is fixed. The contact means 32 extends through a rear side wall 34 of the cover and is, when the cover is closed, in engagement with contact plates 35 which via conductors 36 is connected to the electric motor of the motor-fan unit 14 as well as conductors, not shown, for supplying electric energy to the vacuum cleaner. When the cover is open the contact means are out of engagement with the contact plates which means that no electric energy is supplied to the parts of the electric circuit which is placed in the cover. The inner wall part 28 has an opening 37 covered by a grating 38 which prevents people from getting in touch with electric details above the grating. Between the opening 37 and the integrated circuit board 29 there is a tube shaped wall 39 seperated from the integrated circuit board by a sealing 40. A heat conductive metal plate 41 extends into the area surrounded by the wall 39 and this plate is thermally connected to one or a plurality of the heat generating power components 42 so that heat is easily conducted to the metal plate 41. The power component 42 is a triac, a start-up resistance or some other type of heat generating device. The cooling arrangement works in the following way. Air which is sucked in to the chamber 11 through the hose 20 by means of the motor-fan unit 14 enters into the dust container 12 in which dust is seperated from the air. The air then flows through the walls of the container and the filter 13 into the motor-fan unit from which the air via channels at the rear end of the vacuum cleaner escapes to atmosphere. A part of the air flowing through the chamber 11 also flows through the grating 38 before it leaves the chamber 11 which means that the air when passing the metal plate 41 takes up heat which is transmitted from the power components 42 to the metal plate 41 thereby efficently cooling the components. Tests have shown that a considerable temperature reduction is achieved by means of this arrangement.

Claims: Vacuum cleaner comprising a housing (10) which is provided with; an electric circuit having at least one heat generating power component (42) such as a triac or a start-up resistor; a motor-fan unit (14) for drawing air through a dust container chamber (11) the chamber being provided with an opening (16) through which the dust container (12) can be removed from the chamber, said opening normally being closed by a cover (17), characterized in that the cover (17) encloses the power component and is provided with a heat transmitting surface (41) that is thermally connected to the power component and is placed such that air passing the chamber cools the power component (42). Vacuum cleaner according to claim 1, characterized in that the cover (17) is provided with an outer and an inner wall part (27,28) placed at a distance from one another and that an integrated circuit board with said power component (42) is placed between the wall parts. Vacuum cleaner according to any of the preceding claims, characterized in that the cover is provided with a sleeve (18) or the like to which a hose (20) can be connected. Vacuum cleaner according to claim 2, characterized in that the inner wall part (28) is provided with an air inlet opening (37) communicating with a compartement which is at least partly limited by the heat transmitting surface (41). Vacuum cleaner according to claim 4, characterized in that the air inlet opening (37) is covered by a grating (38).

Inventors: LINDQUIST TOMMY, LINDQUIST, TOMMY
Applicants: ELECTROLUX AB, AKTIEBOLAGET ELECTROLUX
Application year: 1996
Main classification: A47L9
IPC codes: A47L9