The invention relates to improvements in vacuum cleaners in order to reduce air flow losses in air passages through a vacuum cleaner.
The suction efficiency of a vacuum cleaner is determined, besides by the effective power of the electric motor, also to a large extent by the suction effect losses or air flow losses in the air passages through the vacuum cleaner.
Avoiding air flow losses in the air passages is important in all kinds of vacuum cleaners in order to achieve a high suction efficiency and reduce energy consumption. However, it is especially important in vacuum cleaners having an electrical motor powered by batteries. In such a case it is not a preferred option to compensate for air flow losses in the air passages by increasing the motor power, since this will have the effect that the battery power will be used up in a shorter time, necessitating more frequent recharging. As an alternative, the battery power capacity could be increased by providing more batteries in the vacuum cleaner, but this will have the effect that the costs and the weight of the vacuum cleaner also will increase.
Battery powered vacuum cleaners are known in many different embodiments. The most common type of battery powered vacuum cleaners are small hand held units used for easy cleaning of kitchens, motor cars and the like. Due to the battery operation, which eliminates the need for connecting a mains supply cable, it is possible to perform, for example, daily cleaning of a kitchen swiftly and easily. There are also known battery powered vacuum cleaners of a stick-formed type, having a nozzle device in a lower end and a handle in an upper end, by means of which it is possible to vacuum clean floors for example. There are also known battery powered vacuum cleaners being a combination of these two types, that is, a so called 2-in-1 vacuum cleaner comprising a hand held unit which optionally can be inserted into an elongated support body to form a stick-type vacuum cleaner having a nozzle device in a lower end and a handle in an upper end, by means of which, for example, floors easily can be vacuum cleaned, whereas the hand held unit also can be used separately to vacuum clean, for example, tables, worktops or narrow spaces. In this latter type of vacuum cleaner, all of the machinery, such as the motor, fan unit, batteries and debris collector, is positioned inside the comparatively small hand held unit, whereas the support body only functions as a carrier for the hand held unit when vacuum cleaning floors. As a consequence, the available space for the machinery is limited at the same time as the air must be drawn a comparatively long distance from the nozzle device in the lower end of the support body, through the air passages inside the same, and through the hand held unit.
It is an exemplary object of the invention to improve the suction efficiency by reducing the air flow losses in the air passages of a vacuum cleaner.
According to a first exemplary aspect of the invention, it is an object to improve the suction efficiency through the air passages of a vacuum cleaner of a hand held unit type. At least this object may be achieved by a vacuum cleaner according to claims 6, 7, 8 and 11.
According to a second exemplary aspect of the invention, it is an object to improve the suction efficiency through the air passages of a stick formed vacuum cleaner. At least this object may be achieved by a vacuum cleaner according to claims 1, 6, 7, 8 and 12.
According to a third exemplary aspect of the invention, it is an object to improve the suction efficiency through the air passages of a vacuum cleaner of a so called 2-in-1 type comprising a hand held unit and a support body, in which the hand held unit is insertable in order to optionally use the hand held unit separately or as a stick-type vacuum cleaner. At least this object may be achieved by a vacuum cleaner according to claims 1, 3, 6, 7, 8, 12 and 13.
According to a fourth exemplary aspect of the invention, it is an object to improve the suction efficiency through the air passages of a vacuum cleaner having a cyclone-like type of debris collector. At least this object may be achieved by a vacuum cleaner according to claims 6, 7 and 8.
An exemplary embodiment will now be described in the form of a so-called 2-in-1 vacuum cleaner, with reference to the drawings, in which:
A vacuum cleaner of a 2-in-1 type, is shown in
Reference is now made to
Generally, air flow losses in vacuum cleaners can be reduced by: avoiding abrupt contractions or enlargements, changes of the cross sectional shape or sharp direction changes of air passages; avoiding leakage of outside air into the air passages; and preventing clogging of debris in the air passages. In order to render stick-type vacuum cleaners compact, smooth and easy to control during use and cost-effective to manufacture, it is known to attach the nozzle device in a lower end mechanically by means of an articulated joint and pneumatically by means of a flexible hose, preferably in the area behind the articulated joint in order to hide the flexible hose as well as possible behind the articulated joint. Traditionally, this flexible hose has an oval or circular cross section. In order to make the appearance of the flexible hose as discrete as possible, the maximum width of the flexible hose may be restricted. Since the cross section is oval or circular, this has the effect that the cross sectional area of the flexible hose becomes unnecessarily restricted, which increases the air flow losses through the flexible hose.
According to exemplary embodiments of the invention, the flexible hose 11 may have a generally rectangular cross sectional shape. In this way the flexible hose 11 can be made with a comparatively large cross sectional area and still, to a large extent, be hidden behind the articulated joint. This contributes to an attractive appearance of the vacuum cleaner while minimizing the air flow losses. In embodiments in which the air passage 8 in the support body also has a general rectangular cross section, this also has the effect that there will be small or substantially no air flow losses due to changing cross sectional shapes between the nozzle device and the air passage. In the exemplary embodiment, the available space behind the articulated joint may be utilized effectively to the utmost possible extent to hide the flexible hose behind the articulated joint and, at the same time, provide an air passage having a comparatively large cross sectional area. A rectangular or square hose will also be thinner, from a front side to a rear side, than an oval or circular hose having the same cross sectional area. This is advantageous, for example, when vacuum cleaning in narrow spaces under furniture. With a thinner hose it is also possible to lower the articulated joint between the nozzle device and the support body, which likewise facilitates access under furniture. Another advantage is that the movability of the nozzle is increased since the rectangular hose is less likely to contact the floor than an oval circular hose due to the concave walls thereof.
As mentioned before, it is advantageous to maintain substantially the same shape and cross sectional dimension of the air passages at least to the debris collector for the purpose of lowering the air flow losses. By forming the flexible hose with a rectangular or square cross section, it is easier to achieve this object since it normally is more favorable to form the air passages in the support body with a rectangular cross section. In addition, though it is a disadvantage, in respect of restricting the air flow losses, to have air passages with too small cross sectional dimensions, it is also a disadvantage if they are to big. It has been found, according to one embodiment of the invention, that a cross sectional dimension of the air passages between 1.085 to 0.465 square inches (in2) (i.e., 0.07-0.03 square decimeters (dm2)) is optimal for an air flow of between 1098 to 427 cubic inches per second (in3/sec) (i.e., 18-7 liters per second (l/sec)). This is due to the fact that the air flow rate must be sufficiently high to be able to perform vacuum cleaning with a good result.
In order to reduce air flow losses in the air passages, it is also important to prevent clogging of debris in the air passages. However, if any debris should nevertheless get stuck in the air passages, it is advantageous if the vacuum cleaner is constructed such that the debris can easily be removed. Accordingly, in one embodiment of the invention, the flexible hose may be attached to the support body and/or to the nozzle device by a quick release arrangement such that at least one end of the flexible hose easily can be released and any stuck debris can be removed from the hose.
In the shown exemplary embodiment, the upper end of the flexible hose 11 is attached to the support body 2 by means of a quick release fitting 12, which facilitates removing debris that may possibly stick in the flexible hose and eliminates the risk of air flow losses for this reason. The quick release fitting 12 is illustrated in more detail in
In the case of a so called 2-in-1 vacuum cleaners having a small hand held unit, which is insertable in a support body, it has been found that one weak point for air flow losses is the connection between the hand held unit, that is, the tube-shaped air inlet of the hand held unit, and the air passage from the nozzle in the support body. To reduce air flow losses it is beneficial that as little air as possible can be drawn from the outside through this connection and into the air passage. At the same time the hand held unit must be easily and readily releasable from the support body to enable vacuum cleaning with the hand held unit alone. In one embodiment of the invention the connection may be formed by an annular shoulder in the support body, being adapted to abut against the annular rim of the tube-shaped air inlet at the hand held unit, and a bead that is adapted to abut against the outer surface of the air inlet at least partially around its circumference. As explained below, the connection may be formed by an insert sleeve, having an annular shoulder as well as a bead, that is mounted in the air passage in the support body. However, it would also be possible to provide a connection by means of a separate bead-forming element, for example a bead-forming element that is mounted in a circumferential groove in the air passage, and a separate sealing element being positioned on an annular shoulder in the air passage. In order to ensure convenient releasing of the hand held unit from the support body, it may be suitable to provide the sealing bead only partly around the circumference of the tube-shaped air inlet. Preferably, the insert sleeve, or separate bead and sealing elements, are formed of a material that is at least slightly resilient to ensure sealing abutment against the air inlet tube of the hand held unit.
Battery powered vacuum cleaners and especially hand held units, are often equipped with a debris collector in form of a cyclone-like separator to separate the debris from the air flow. One main reason for this is that the available space in the debris collector of battery powered vacuum cleaners is too small for bags of ordinary size, and would necessitate an unwanted frequent replacement of bags. It has been found that the shape of the air channel and the inlet opening to the cyclone-like separator can be important for reducing the air flow losses in the vacuum cleaner. According to one exemplary embodiment of the invention, the air passage from the air inlet of the hand held unit may be curved and have an inlet opening into the cyclone-like separator that is positioned off-center in relation to the symmetry plane of the cyclone-like separator. In this arrangement, the air flow enters the cyclone-like separator substantially in the tangential direction in the upper periphery of the cyclone-like separator. Thereby direction changes of the air passage at the inlet opening into the cyclone-like separator are reduced, and air flow losses are lowered.
An example of the foregoing embodiment is illustrated in
To restrict the air flow losses in the hand held unit from the inlet tube 9 to the cyclone-like separator, an air channel 18 in the hand held unit has, according to this exemplary embodiment of the invention, been formed with a curved shape. The broken lines indicate the extension of the air channel 18 and an outlet opening 20 to the debris container 7. In
To direct the air flow inside the cyclone-like separator, there may be provided a partition wall between the filter insert and the inner surface of the debris container. This partition wall may extend from the inlet opening of the cyclone-like separator to preferably at least about one quarter to half the distance around the filter insert. At an end portion distant from the inlet opening, the partition wall may be curved in the direction towards an end of the filter insert, in order to smoothly direct the air flow helically around the filter insert.
An exemplary embodiment of a partition wall is shown in
The air flow around the filter insert is further illustrated in
In the shown exemplary embodiment, the parts form an air passage between the filter, the inner surface of the debris container, an end wall of the debris container and the partition wall 24, which may have substantially the same shape and cross sectional area dimension as the air passage 18 through the support body. In the shown embodiment, this passage is substantially rectangular, has mainly the same shape and cross sectional size as the air passage 18 in the support body, is defined between the filter surface, the inner surface of the debris container, an end wall of the debris container and the partition wall, and extends about a quarter to half of the distance around the filter insert. This may be advantageous with respect to restricting air flow losses and maintaining a sufficient air flow rate, as mentioned before, and creates a favorable air flow inside the cyclone-like separator.
After passing through the filter insert in the cyclone-like separator, the air flow is passed to the motor-fan unit through an inlet opening. According to an exemplary embodiment of the invention, the inlet opening to the motor-fan unit may be funnel-shaped in order to reduce air flow losses when the air flow is transferred from the cyclone-like separator to the motor-fan unit after passage through the filter insert. Further, according to regulations in most countries, the inlet opening to the motor-fan unit has to be covered by an intake screen to prevent physical injuries from the rotating fan. In order to reduce air flow losses, the intake screen may be formed with a domed shape. This is beneficial for the reduction of air flow losses in two different ways. On the one hand, this has the effect that the area of the intake screen will become larger such that the total area of the air flow openings through the intake screen can be made larger. On the other hand this has also the effect that the intake screen will become stronger, due to the dome-shape, which can be utilized to reduce the cross-sectional dimensions of individual screen members, which also will reduce the air flow losses through the intake screen.
To reduce the air flow losses through a vacuum cleaner, it also may be important not to unnecessarily slow down the air flow through the air exhaust section from the fan unit. Therefore, in one exemplary embodiment of the invention, the vacuum cleaner may be provided with a first air outlet on a front side as well as a second air outlet on a rear side. This feature can be incorporated in a hand held unit, in a stick formed vacuum cleaner, as well as in a 2-in-1 type of vacuum cleaner. In the latter case the hand held unit is provided with a first air outlet in the front side and a second air outlet in the rear side, whereas the support body is provided with air flow openings in the rear side of the recess for accommodating the hand held unit, which substantially coincide with the second air outlet.
An exemplary example of the foregoing arrangement is shown in the Figures. According to this exemplary embodiment of the invention, the hand held unit is provided with a first air outlet 37 on the front side as well as a second air outlet 38 on the rear side, as can be seen, for example, from
It is to be understood that it is within the scope of the invention that all the features, mentioned in this specification, for reducing air flow losses through a vacuum cleaner, can be applied separately in a vacuum cleaner or in any combination. It will also be understood that variations to the foregoing exemplary embodiments may be made without departing from the spirit of the inventions described herein, and the description of various exemplary embodiments is not intended to limit the scope of the invention.
Number | Date | Country | Kind |
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0700143 | Jan 2007 | SE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/SE2008/000043 | 1/18/2008 | WO | 00 | 12/7/2009 |
Publishing Document | Publishing Date | Country | Kind |
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WO2008/088278 | 7/24/2008 | WO | A |
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