Device for a vacuum cleaner

Abstract

 A vacuum cleaner including a vacuum source in the form of a fan arrangement (15) comprising a fan unit (22). The fan unit (22) is driven by a commutator motor (23) via a shaft (30). The commutator (24) is received in a separate chamber (31), which is sealed from the other parts of the electric motor. The chamber is connected to an inlet channel (36) and an outlet channel (37). Air flows through the chamber and takes up carbon particles from the commutator and delivers same to a dust bag.

Description

[0001] The present invention relates to a device for a vacuum cleaner comprising a vacuum source in the form of a fan arrangement comprising a fan unit which, via a shaft, is driven by a motor unit in the form of a commutator motor.

[0002] Vacuum cleaners of the type mentioned above are previously known. One problem in vacuum cleaners having commutator motors is that carbon particles are torn away from the carbon brushes during operation and these particles follow the air flow which is created by the fan and which is normally used to cool the electric motor. In order to collect these particles, and to take care of smaller particles which are not taken up by the dust bag of the vacuum cleaner, special fine filters which can easily be exchanged are used at the outlet side of the vacuum cleaner. However, the fine filters, which are rather expensive, are quickly filled with carbon particles. The carbon particles discolor the filter and cause an increased flow resistance and, hence, need to be changed relatively often.

[0003] It is also previously known to use a separate fan to cool the electric motor. However, using a dedicated motor-cooling fan complicates the vacuum cleaner and motor design. In order to achieve a reasonable pressure drop with a limited filter area, a course mesh filter with a low flow resistance is used. Coarse mesh filters do not, however, prevent carbon particles from leaving to atmosphere.

[0004] U.S. Patent No. 3,791,774 describes a vacuum cleaner having a commutator motor in which the carbon particles are collected on a plate inside the motor. The cooling air flow through the motor takes up the carbon particles and the direction of the air flow is abruptly changed, causing the particles to be thrown against the plate on which they are collected. However, this arrangement has certain disadvantages. Firstly, there is no means for taking care of the small carbon particles which will inevitably follow the air flow to the outlet. Secondly, cleaning of the plate is problematic since the plate is a part of the motor. Accordingly, the motor has to be removed from the vacuum cleaner in order to access the plate.

[0005] It should also be mentioned that it is previously known in connection with electric machines, see GB 2144924, to provide a closed chamber surrounding the commutator and to blow air through the chamber in order to expel the carbon particles to atmosphere. Thus, this arrangement does not relate to a vacuum cleaner and there is no intention to filter or trap the carbon particles.

[0006] An object of the present invention is to provide an arrangement for a vacuum cleaner which takes care of the carbon particles from the brushes in a simple way by means of an air flow in close connection with the commutator, and delivers the particles to a place where they can be separated from the air flow. This object is achieved by a small amount of air which simultaneously assists in cooling the commutator, the brush holders, and the bearings of the electric motor. Since the amount of air is very limited, the air is preferably taken in before the dust bag at the suction side of the fan without considerably reducing the suction efficiency of the nozzle. Thus, the carbon powder will also be drawn into the dust bag and be separated from the air flow in the bag, which means that the carbon powder will never reach the outlet filter, if any, on the pressure side of the fan. Thus, replacement of the dust bag means that the collected carbon powder is also removed from the vacuum cleaner.

[0007] These and further features of the invention will be apparent with reference to the following description and drawings, wherein:

FIG. 1 is a schematic vertical section through a vacuum cleaner which is provided with a device according to the present invention; and,

FIG. 2 is a vertical section through the fan unit of the vacuum cleaner according to the present invention.

[0008] A vacuum cleaner 10 according to the present invention comprises a shell 11 enclosing a chamber 12 for a dust container 13, a motor housing 14 enclosing a motor-fan unit 15, and a chamber 16 receiving a cable reel 17. The dust container 13 is connected, via a sleeve 18, to a vacuum cleaner hose 19. The vacuum cleaner hose 19 is connected to a tube shaft and a nozzle (not shown). The dust container 13 comprises a plate 20 of comparatively stiff material to which an air-pervious bag 21, preferably of paper, is fixed.

[0009] The motor-fan unit 15 comprises a fan unit 22 and a motor unit 23. The motor unit 23 includes a commutator motor with a conventional commutator-carbon brush arrangement 24. The inlet side of the fan unit 22 communicates, via an inlet part 25, with the chamber 12. The inlet part 25 is covered by a catastrophe filter 26. The catastrophe filter prevents larger particles or debris from being drawn into the fan unit 22 if the dust container 13 should break.

[0010] The air flow leaving the fan unit 22 flows over the motor unit 23 in order to cool the motor before exiting to atmosphere via openings (not shown) in the shell. The shell 11 also has one or more openings 27 through which air is drawn into the chamber 16 in order to cool the cable reel 17.

[0011] As shown in FIG. 2, the fan unit 22 comprises a two stage fan with the impellers 28 placed in a fan housing 29 on a common shaft 30. The shaft 30 is driven by the motor unit 23 provided with a commutator motor 24. The commutator 24 is arranged in a closed pocket 31 which also comprises a bearing housing 32 for one of the bearings 33 on which the shaft 30 is supported. The closed pocket 31 is thus limited or defined by the motor housing 34, the bearing housing 32 and an annular sealing gasket 35 surrounding the commutator 24. The pocket 31 has two openings, each of which are provided with a nipple to which two conduits 36 and 37 are connected. One conduit 36 is connected to the chamber 16, while the second conduit 37 is connected to the sleeve 18, as shown in FIG. 1.

[0012] The device operates in the following manner. During the operation of the vacuum cleaner, working air is drawn through the nozzle, and the hose 19, and into the dust bag 13. Dust is separated from the air in the bag 13 and the cleaned air flows into the fan unit 22. The cleaned or filtered air flows over the motor 23 and cools the motor before exiting to atmosphere via an optional fine filter.

[0013] Simultaneously, relatively cold ambient air is drawn through the opening 27 and into the chamber 16. The ambient air cools the cable reel 17, and flows through the conduit 36 to the pocket 31. In the pocket 31, the air flow cools the commutator 24, the carbon brushes and the bearing 33 and, at the same time, takes up the carbon particles which are released from the commutator brushes. Thereafter, the air flows through the conduit 37 to the sleeve 18 wherein it mixes with the working air flowing therethrough. The carbon particles will follow the working air into the dust bag 13 and collect on the filter surfaces. The filtered carbon particles will thus be removed from the vacuum cleaner when the dust bag 13 is replaced.

[0014] It should be observed that it, of course, is possible to create the air flow through the pocket 31 by other means than what has been mentioned above. For instance, the air flow could be created by supplying a minor part of the air flow from the pressure side of the fan to the pocket, or by using some kind of pump or fan and simultaneously placing a smaller filter for taking up the carbon particles after the pocket, as seen in the direction of flow.

[0015] The present invention also makes it possible to not use a separate outlet filter after the dust bag. Accordingly, there is no need for a careful sealing arrangement on the pressure side of the fan which, up to now, has been necessary in order to prevent the carbon particles from leaking out of the air channels between the fan and the outlet filter.

Claims

1. A vacuum cleaner comprising a fan unit (22) which is driven by a motor unit (23), said motor unit being a commutator motor, characterized in that a commutator (24) of said motor is received in a separate chamber (31) which is sealed from other parts of the motor unit, said chamber being connected to an inlet channel (36) and an outlet channel (37), wherein air is introduced into said chamber via said inlet channel and is removed from said chamber via said outlet channel, carbon particles from the commutator exiting said chamber with said air via said outlet channel, said outlet channel (37) being connected to a filter (21), which is operable to collect said carbon particles.

2. A vacuum cleaner according to claim 1, characterized in that a bearing (33) for said shaft (30) is disposed within said chamber (31).

3. A vacuum cleaner according to claim 1 or 2, characterized in that the fan unit (22) causes air to flow through the chamber (31).

4. A vacuum cleaner according to any of the preceding claims, characterized in that the outlet channel (37) is connected to an air flow channel placed upstream of the filter (21).

5. A vacuum cleaner according to any of the preceding claims, characterized in that the filter (21) is an air-pervious dust bag, said dust bag being disposed within the vacuum cleaner.

6. A vacuum cleaner according to claim 5, characterized in that the outlet channel (37) is connected to a sleeve (18), said sleeve being inserted into the dust container (13).

7. A vacuum cleaner according to any of the preceding claims, characterized in that the inlet channel (36) is connected to atmosphere via an additional chamber (16) in the vacuum cleaner, said additional chamber housing a cord reel (17).

Drawing