WO2010107896A1

WO2010107896A1 - Vacuum cleaner sensor

Info

Publication number: WO2010107896A1
Application number: PCT/US2010/027637
Authority: WO
Inventors: Fredrik Sjoberg
Original assignee: Electrolux Home Care Products, Inc.
Priority date: 2009-03-17
Filing date: 2010-03-17
Publication date: 2010-09-23
Also published as: GB2481546A; WO2010107896A8; CN102421347A; GB201116066D0; US20100236013A1

Abstract

A vacuum cleaner having an inlet nozzle for conveying air and dust to a dirt separator chamber via a dirty air inlet passage is provided. The dirt separator chamber has a chamber opening, an emitter window, and a receiver window. The emitter window and the receiver window may be substantially transparent. An emitter is positioned so that it emits light or another electromagnetic energy into the separator chamber via the emitter window. A receiver is positioned so that it receives light or another electromagnetic energy from the separator chamber via the receiver window. The emitter window and the receiver window each form a projection into the separator chamber during operation of the vacuum cleaner. Airflow creates a cyclone in the dirt separator chamber, and the projections increase the air velocity over the projections, cleaning the emitter window and the receiver window of dust.

Description

VACUUM CLEANER SENSOR

FIELD OF THE INVENTION

[01] The present invention relates to features for use with vacuum cleaners that employ a cyclonic cleaning system, such as upright vacuum cleaners, commercial vacuums, stick vacuums, canister vacuums, central vacuums, and the like.

BACKGROUND OF THE INVENTION

[02] Vacuum cleaning devices, such as upright and canister vacuum cleaners, stick vacuums, electric brooms and other devices, are in widespread use as tools to clean floors, upholstery, stairs, and other surfaces. Known vacuum cleaning devices have various features intended to improve their utility or cleaning effectiveness. For example, pressure sensors in a vacuum cleaner may detect when the bag is full of dust or indicate when the user should replace the bag or filters, or empty the dust cup. The pressure sensor device alerts the user to replace the bag or dust cup, and makes it less necessary to check the bag manually. Using a cyclone separator vacuum, windows to view the cyclone separator may be useful to determine the level of dust in the cyclone separator. However, dirt may be spun against the walls of the cyclone separator, obscuring the view from the windows.

[03] While the prior art provides various features relating to cleaning effectiveness and user convenience, there still exists a need for improvement of and alternative designs for these and other features of vacuum cleaning devices.

SUMMARY OF THE INVENTION

[04] In a first exemplary aspect, there is provided a vacuum cleaner that has an inlet nozzle for conveying air and dust to a dirt separator chamber via a dirty air inlet passage. The dirt separator chamber has a chamber opening, an emitter window, and a receiver window. The emitter window and the receiver window may be substantially transparent. An emitter is positioned so that it emits light or other electromagnetic energy into the separator chamber via the emitter window. A receiver is positioned so that it receives light or other electromagnetic energy from the separator chamber via the receiver window. One or both of the emitter window and the receiver window forms a projection into the separator chamber during operation of the vacuum cleaner.

[05] In another exemplary aspect, there is provided a vacuum cleaner that has an inlet nozzle for conveying air and dust to a dirt separator chamber via a dirty air inlet passage. The dirt separator chamber has a chamber opening, an emitter window, and a receiver window. One or both of the emitter window and the receiver window forms a projection into the separator chamber. Air flows into the dirt separator chamber from the inlet nozzle and the dirty air inlet passage, and the air is formed into a cyclone either inside the dirt separator chamber, or before the air gets to the dirt separator chamber. The velocity of the air in the cyclone increases as the air passes over the projections of the emitter window and the receiver window. The velocity over the projections may be increased by at least about 10%, and more preferably by at least about 40%. In exemplary aspects, the velocity may increase from about 10 meters per second to at least about 11 meters per second, and more preferably to at least about 14 meters per second.

[06] The recitation of this summary of the invention is not intended to limit the claimed invention. Other aspects, embodiments, modifications to and features of the claimed invention will be apparent to persons of ordinary skill in view of the disclosures herein. Furthermore, this recitation of the summary of the invention, and the other disclosures provided herein, are not intended to diminish the scope of the claims in this or any prior or subsequent related or unrelated application. BRIEF DESCRIPTION OF THE DRAWINGS

[07] The present invention is described in detail with reference to the examples of embodiments shown in the following figures in which like parts are designated by like reference numerals.

[08] Figure l is a schematic cross sectional view of an exemplary embodiment of a vacuum cleaner having a dirt cup releasably positioned within a housing, where the dirt cup has internal, self-cleaning projections to facilitate the operation of an emitter and a receiver located outside the dirt cup.

[09] Figure 2 is a partial schematic perspective view along plane T of Figure 1.

[10] Figure 3 is a partial schematic cross sectional view of along plane T of Figure 1.

[11] Figure 4 is a partial schematic cross sectional diagram view along plane T of Figure 1.

[12] Figure 5 is a cross-sectional view of the separator chamber of Figure 1, with arrows designating exemplary airflow therein.

[13] Figure 6 is an isometric view of an alternative embodiment of a separator chamber of the present invention.

[14] Figure 7 is a cross sectional view of another embodiment of a window of the present invention, showing a membrane window in a "resting" position.

[15] Figure 8 is a cross section view of another embodiment of a window of the present invention, showing a membrane window in an "active" position.

[16] Figure 9 is another embodiment showing an emitter and a receiver on the same side of a window. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTIONS

[17] The present disclosure provides numerous inventive features for vacuum cleaners. A number of these features and alternative embodiments of the invention are described with reference to their exemplary use in an upright vacuum cleaner, such as the vacuum cleaner shown in partial view in Figure 1. It will be appreciated, however, that the features described herein can be used in various other contexts. For example, the various features described herein can be used with canister vacuums, stick vacuums, portable and handheld vacuums, shop vacuums, central vacuum systems, and so on. Furthermore, the various features described herein may be used separately from one another or in any suitable combination. The present disclosure illustrating the use of the various inventions described herein is not intended to limit the inventions in any way. Moreover, not all of the parts of a typical vacuum cleaner (such as the vacuum fan and motor, inlet nozzles, filters, etc.) are shown, but they will be readily understood by persons of ordinary skill in the art. Only parts relevant to demonstrate the operation of the various inventions described herein are shown.

[18] Referring to Figure 1, a typical vacuum cleaner housing 105 includes a motor (not shown) and a dirt separator assembly (shown cut away). The housing 105 may be formed from a plastic or metal material, and may also include other components. For example, the housing 105 may include one or more wheels (not shown) mounted to the outer surface of the housing 105 to allow the housing 105 to roll. The motor and the dirt separator assembly may be attached to the vacuum cleaner housing 105. In an alternate embodiment, the motor and dirt separator assembly may be attached to one or more structures separate from the housing 105, but may be in communication with the housing 105 through hoses, as known in the art. Examples of vacuum cleaners having various housing configurations and with which the present invention may be used are provided in the attached U.S. Pat. Nos. 6,502,277; 5,935,279; 7,163,568; 5,813,085; 6,829,804; and 6,910,245, which references are incorporated into the present disclosure. The illustrated exemplary embodiment is used in a device similar to the two-stage cleaners shown in 5,935,279 and 6,910,245, but it may be adapted for use in single-stage cleaners or other kinds of cleaning device.

[19] The dirt separator assembly 100 may be removably attached to the housing 105, and mounted by tabs, hooks, latches or other well-known devices. The dirt separator assembly 100 may include an inlet 102 that receives dirt and air from a dirty air inlet on the vacuum cleaner (not shown), and an outlet 104 that conveys air substantially removed of the dirt to a vacuum fan associated with the motor (not shown). The dirty air inlet (not shown) is associated with, for example and without limitation, a floor or inlet nozzle or an above-floor cleaning hose. Suction created by the motor creates a vacuum that draws air and dirt through the floor nozzle or the above-floor cleaning hose. The combined air and dirt enter the dirt separator assembly 100, where the dirt is substantially removed from the air. The dirt may be removed by the air by, for example, the creation and maintenance of a cyclone inside the dirt separator assembly 100, which may force the dirt out of the cyclone and into the dirt separator assembly 100. A filter of screen (not shown) may also be used to remove dirt from the air. When the dirt separator assembly 100 is attached to the housing 105, the dirty air inlet of the dirt separator assembly 100 may be associated with the floor nozzle or the above- floor cleaning hose, and the outlet may be associated to the vacuum fan and the motor. In other embodiments, the motor may be located between the inlet and the dirt separator assembly, in which case it will force air through the dirt separator assembly under positive pressure, as opposed to operating under negative pressure as in the embodiment described above.

[20] The motor (not shown) may be contained within the housing 105, and may include a vacuum fan. The motor may be any type of device to operate the vacuum fan as known in the art, and may include, for example and without limitation, an electric motor. The motor may operate the vacuum fan to create a suction. The motor may be, for example, an electric motor that is in electrical communication with one or more power supplies. The one or more power supplies may draw electricity from, for example and without limitation, one or more power outlets. In another embodiment, the one or more power supplies may be in communication with one or more batteries. The batteries may provide electricity to the power supply, or may provide electricity to the motor directly. Both one or more power supplies and one or more batteries may be present, and may provide electricity to the motor alternately or in parallel. The one or more power supplies and/or the one or more batteries may be contained within the housing 105, or may provide electricity to the elements contained in the housing 105 via a cable or other electricity transfer device.

[21] The separator chamber 110 includes an emitter window 120 and a receiver window 130. The separator chamber 110 may be substantially cylindrical, or may be another shape to promote air to form a cyclone or another substantially circular or helical motion. The separator chamber 110 may be formed from the same material as the emitter window 120 and the receiver window 130, or the separator chamber 110 may be formed from a different material from the emitter window 120 and/or receiver window 130. For example, the separator chamber 110 may be formed from an opaque material, and the receiver window 130 and the emitter window 120 may be formed from a optically translucent material. The separator chamber 110 is removably attached to the housing 105, and is attached to the housing 105 so that an emitter 127 is capable of transmitting electromagnetic energy into the separator chamber 110 via the emitter window 120, and a receiver 137 is capable of receiving electromagnetic energy from the separator chamber 110 via the receiver window 130. The emitter window 120 and the receiver window 130 are shaped such that they are discontinuous from the inner surface of the separator chamber 110, and form projections within the inner wall of the separator chamber 110. In other embodiments, however, the emitter window 120 or the receiver window 130 may simply comprise a portion of the separator chamber 110 wall. The emitter window 120 and/or the receiver window 130 may also be provided as projections that extend the length of the separator chamber 110. An example of such an embodiment is shown in Figure 6, in which a separator chamber 610 is provided having an emitter window 620 and a receiver window 630 formed as full-length shapes. In the embodiment of Figure 6, the use of such full-length shapes may facilitate manufacture of the separator chamber 610. Also in this embodiment, the emitter and receiver can be placed at any desired location along the emitter and receiver windows 620, 630, and multiple sets of emitters and receivers may be used to provide readings at various locations.

[22] The emitter window 120 may be formed from the same material as the separator chamber 110 wall, or may be formed from a different material and attached to the separator chamber 110 wall in a manner known in the art. The emitter window 120 may comprise an inner emitter window surface 121 and an outer emitter window surface. The emitter window 120 is formed from a material that allows some or substantially all of the electromagnetic energy transmitted by the emitter 127 to enter the separator chamber 110.

[23] The inner emitter window surface 121 is shaped so that the inner emitter window surface 121 projects into the separator chamber 110. The inner emitter window surface 121 projection may form a curve that extends into the separator chamber 110. The faces 123a and 123b of the inner emitter window surface 121 that face the axial line of the separator chamber 110 may be flat, or substantially normal to the separator chamber 110 surface, or the faces 123a and 123b of the emitter window surface that face the axial line of the separator chamber 110 may be angled or curved. The outer emitter window surface may be flush or continuous with the separator chamber 110 wall's outer surface, or may be discontinuous with the separator chamber 110 wall's outer surface. [24] The receiver window 130 may be formed from the same material as the separator chamber 110 wall, or may be formed from a different material and bonded with the separator chamber 110 wall in a manner known in the art. The receiver window 130 may comprise an inner receiver window surface 131 and an outer receiver window surface. The receiver window 130 is formed from a material that allows some or substantially all of the electromagnetic energy transmitted by the emitter 127 and entering the separator chamber 110 through the emitter window 120 to pass through the receiver window 130 and be received by the receiver 137. The inner receiver window surface 131 may be substantially similar to the inner emitter window surface 121, including with respect to the faces 123a and 123b of the inner emitter window surface 121 and the faces 133a and 133b of the inner receiver window surface 131. The outer emitter window surface and the outer receiver window surface also may be substantially similar. Of course, in other embodiments, the inner and outer receiver window surfaces may be shaped differently than the inner and outer emitter window surfaces.

[25] As noted above, it will be appreciated that the emitter window 120 and receiver window 130 can be made in any suitable way. For example, they may be molded integrally with the separator chamber 110 wall. As another example, the separator chamber 110 may be constructed with openings into which the emitter and receiver windows 120, 130 are installed. As still another example, the separator chamber 110 wall may be constructed as a continuous wall (as typically done in the prior art), and the emitter window 120 and receiver window 130 may be formed by attaching additional material to the inner surface of the separator chamber 110 wall to form projections therein.

[26] Turning now to Figures 2, 3, and 4, various exemplary views of the vacuum cleaner shown in Figure 1 are shown along plane T. The emitter 127 and receiver 137 preferably are mounted to the housing 105 and remain with the housing even when the separator chamber 110 is removed for emptying, but this is not required in all embodiments. The emitter 127 may be retained in an emitter housing 125, which may be formed from the same material as the housing 105, and may be formed, for example, when the housing 105 is formed. The emitter housing 125 includes one or more attachment points for the emitter 127. For example, the emitter housing 125 may include one or more projections to which the emitter 127 and associated circuitry may be attached by screws or rivets or the like. The construction of emitters and the attachment of the same to vacuum cleaner housings are known in the art, and the details need not be described herein. The emitter housing 125 is positioned within the housing 105 so that the emitter 127 aligns with the emitter window 120 on the separator chamber 110 when the separator chamber 110 is mounted to the housing.

[27] The emitter 127 may be any electronic apparatus capable of transmitting electromagnetic energy. For example, the emitter 127 may emit visible light, or may emit infrared or ultraviolet light. The emitter window 120 of the separator chamber 110 is capable of transmitting the electromagnetic energy of the emitter 127 into the separator chamber 110. For example, if the emitter 127 emits visible light, then the emitter window 120 may be capable of transmitting some or all of the visible light emitted from the emitter 127 into the separator chamber 110. The emitter 127 is positioned so that the emitter 127 transmits the electromagnetic energy in the general direction of the emitter window 120. If desired, the emitter window 120 may be shaped to help direct the electromagnetic energy towards the receiver window 130. It will also be appreciated that the emitter window 120 may be shaped as a lens to focus or spread the energy. The emitter 127 may be in electrical communication with a power supply (not shown), as known in the art, and may be operated continuously or periodically by any suitable control circuitry.

[28] The receiver 137 may be mounted to the housing 105 in a receiver housing 135, which may be formed from the same material as the housing 105, and may be formed, for example, when the housing 105 is formed. The receiver housing 135 includes one or more attachment points for the receiver 137. For example, the receiver housing 135 may include one or more projections to which the receiver 137 and associated circuitry may be attached by screws or rivets or the like, as known in the art. The receiver housing 135 is positioned within the housing 105 so that the receiver 137 aligns with the receiver window 130 when the separator chamber 110 is mounted to the housing 105.

[29] The receiver 137 may comprise any electronic apparatus capable of receiving and detecting electromagnetic energy. For example, the receiver 137 may receive and detect visible light, or may detect infrared or ultraviolet light. The receiver 137 is capable of detecting the electromagnetic energy from the emitter 127 (at least when there is nothing obstructing the energy path), so that if the emitter 127 emits, for example, visible light, the receiver 137 is capable of detecting the visible light. The receiver 137 is positioned so that the receiver 137 may receive the electromagnetic energy from the general direction of the receiver window 130, and the receiver window 130 may be shaped to help direct the energy from the emitter window 120 to the receiver 137. It will also be appreciated that the receiver window 130 may be shaped as a lens to focus or spread the energy. The receiver 137 may be in electrical communication with a power supply (not shown), as known in the art, and may be operated continuously or periodically by any suitable control circuitry.

[30] Together, the emitter 127 and receiver 137 are operated to evaluate the amount of dirt or dust in the separator chamber 110. For example, the emitter 127 may be energized to emit electromagnetic energy, and the receiver 137 may be used to determine how much of the energy is received. The signal from the receiver 137 may vary depending on the amount of energy received. The amount of signal loss may be measured to determine the amount and nature of the dirt in the separator chamber 127. For example, if no signal is received, then the chamber may be obstructed with dirt at the level of the emitter 127 and receiver 137, indicating that it should be emptied. More than one emitter 127 and more than one receiver 137 may be used in an embodiment. For example, a number of emitters 127 and a number of receivers 137 may be arranged so that different levels of dirt in the separator chamber 127 may be detected. In other embodiments, the emitter 127 and/or receiver 137 may comprise a cluster of multiple emitter elements and/or receiver elements at generally one location. Additionally, more than one emitter window 120 and more than one receiver window 130 may be formed with the separator chamber 110 wall. As another example, the signal may be detected to include rapid, large fluctuations, indicating that relatively large particles are passing through the cyclone. As another example, the signal may be fluctuating with a relatively small amplitude, indicating that smaller particles are passing through the cyclone.

[31] The emitter 127 and the receiver 137 may be continuously energized while the vacuum is in operation, and the signal generated by the receiver 137 may be continuously monitored by the control logic. In another embodiment, the emitter 127 and receiver 137 may be energized at the start of the operation of the vacuum, or at the end of the operation of the vacuum, or may be selectively energized and the signal monitored at discrete intervals. In yet another embodiment, the control logic may presume that the separator chamber 110 is obstructed by dust and/or debris at the start up of the vacuum, and may energize a light to indicate that the separator chamber is obstructed. If, after the signal from the receiver 137 is evaluated, the control logic determines that the separator chamber 110 is not sufficiently obstructed, the control logic may de-energize the light to indicate that the separator chamber 110 is not obstructed. The control logic may then continue to monitor the signal from the receiver 137, or may not monitor the signal from the receiver 137 until the vacuum is restarted.

[32] Of course, the emitter 127 and receiver 137 may be calibrated to account for actual or expected losses of energy through a clean or empty separator chamber 110. In such a case, the calibration may be performed at the factory (e.g., by including a simple loss factor into the control logic), or it may be performed in use by using the signal loss after each cleaning as a baseline loss for that cleaning session (e.g., by resetting the sensor baseline loss level each time the separator chamber 110 is emptied or providing a manual reset button). The emitter 127 and receiver 137 may be calibrated so that if an actual or expected loss of energy through a clean or empty separator chamber 110 is not found (i.e., the energy received by the receiver 127 is higher than what would be expected if the energy passed through a clean or empty separator chamber 110), it may be recognized that the separator chamber 110 is not seated or is seated improperly. In a situation where the separator chamber 110 is not seated or is seated improperly, the control logic may not allow the motor (not shown) to start, or may stop the motor if it is running. The control logic may also energize an error light or similar indicator to note that the separator chamber 110 is not seated properly or is missing. The emitter 127, receiver 137 also may be oriented and arranged such that they rely on their windows 120, 130 to direct the emitted energy from the emitter 127 to the receiver 137. In such an embodiment, the receiver 137 does not receive any appreciable amount of energy from the emitter 127 unless the dirt separator assembly 100 is properly installed in the housing 105. This embodiment can be used to indicate a fault condition when the dirt separator assembly 100 is not properly installed.

[33] The foregoing and/or other control methods may be used, as known in the art, to provide the user with an indication of the type and/or amount of dirt that is passing through the separator chamber 110 or other functions, such as to indicate that the separator chamber is missing.

[34] When the vacuum cleaner is switched on, the motor (not shown) creates a vacuum. Air and dirt are drawn into the vacuum cleaner via the inlet 102. The inlet 102 directs the air and dirt into the separator chamber 110, where the chamber walls, shape of the inlet, and the pressure difference between the inlet and the outlet create one or more cyclones or other substantially circular or helical airflow patterns. As known in the art, one or more filters or screens may be located within the chamber 110 to help create a cyclone and/or filter the air leaving the separator chamber 110. The vacuum may comprise a single cyclone, or, as in the shown embodiment, may comprise a multiple stage cyclone separator system. In the shown embodiment, the separator chamber 110 in which the emitter and receiver operates is the first stage 140 of a two-stage cyclone. A filter (not shown) may be located in the separator chamber 110, and the windows and sensors may be located below the filter, or at the level of the filter but oriented so that the filter does not obstruct the operation of the sensors. Air leaving the first stage 140 passes into a second stage cyclone 150, which deposits removed particles into an associated chamber 152.

[35] Within the separator chamber 110, the air rotates generally tangentially with respect to the separator chamber 110 walls, as known in the art. While embodiments described herein are referred to as "cyclones," it will be understood that embodiments may be used with any kind of centrifugal separator, or even with devices that do not use centrifugal or cyclone flow. This rotation applies a radial centrifugal force that pushes the dust from the inside of the separator chamber 110 to the wall of the separator chamber 110. As the dust and larger particles are separated, they tend to settle in a lower portion 142 of the separator chamber 110. One problem discovered with cyclone separator chambers is that dirt and dust tends to cling to the wall of the separator chamber 110 both during and after operation of the vacuum cleaner. Such clinging dirt may interfere with the operation of the transmitter 127 and receiver 137 by reducing the strength of the signal reaching the receiver 137.

[36] Turning now to Figure 5, there is shown an exemplary cross-sectional view of the separator chamber 110, with arrows designating the airflow along the boundary layer adjacent the inner wall of the separator chamber 110. The inner surface of the wall includes an exemplary projection 510, which may be the inner emitter window surface 121 or the inner receiver window surface 131. Only one of the window surfaces is shown as an example in this figure, but a similar analysis and results are obtained with multiple projecting window surfaces. As shown, the air flows around the separator chamber 110, and is directed away from the outer wall as it passes over the projection 510. As the air passes over the projection 510, its velocity increases, for reasons that are explained according to the well-known principles of fluid dynamics. The boundary layer of the cyclonic air in the separator chamber 110 also may decrease as the air passes over the projection 510. Without being bound by any theory of operation, it is believed that the increased air flow velocity, as well as the decreased boundary layer size, at the projection 510 help dislodge dust particles from the projection 510 surface. This provides a cleaning action, generally not present throughout the remainder of the separator chamber 110 wall, that helps keep the projection 510 free of accumulated dust and operating properly. It is believed that the velocity of the airflow passing over a projection 510 (such as the one shown or over similar projections formed as emitter and/or receiver windows) can be increased by 10%, 40%, 50%, or more. For example, it has been calculated that the airflow velocity may increase from about 5 to 10 meters per second without projections being present, to about 11 meters per second, about 14 meters per second, or about 15 meters per second at locations where a projection 510 is provided. In one simulation, it was calculated that adding projections increased the airflow over the projections to about 150% of the value at locations where no projections were present, and decreased the boundary layer (i.e., the portion of the airflow between the wall surface and the location at which peak velocity is obtained) to about 80% of the value at locations where no projections were provided.

[37] The airflow in Figure 5 indicates a clockwise cyclone rotation, but a counterclockwise rotation may be used instead. Furthermore, the projection 510 may be optimized for a particular rotation direction (i.e., clockwise or counterclockwise). The projection 510 also may be oriented along a helical path to account for vertical movement of the airflow. If desired, features may be provided to help make the air flow over the projections in a regular pattern. For example flow control planes may be provided along the upper and lower walls of each projection. Other variations will be apparent to persons of ordinary skill in the art in view of the present disclosure.

[38] One particular advantage of some embodiments of the invention (which advantage is not required in all embodiments, of course) is that the separator chamber 110 may be removed from the housing 105 for cleaning, maintenance, and/or replacement without removing the emitter 127 or receiver 137. The emitter window 120 and the receiver window 130, being attached to the separator chamber 110, are also removed with the separator chamber 110 for cleaning. A user may clean the inner surface of the separator chamber 110, including the inner receiver window 130 and the inner emitter window 120, to remove accumulated dust that is not removed by the increased air velocity and decreased boundary layer, and thereby restore the device to its most favorable operating conditions. To this end, forming the emitter and receiver windows 120, 130 with projections has the added advantage of providing visual and tactile indicators to help direct the user to areas requiring attention during cleaning. While such cleaning may be desirable, it may not be required, and it is expected that typical users will not specifically clean the windows 120, 130 during regular cleaning. Once cleaned, the user may then replace the separator chamber 110 within the housing 105. When the user replaces the separator chamber 110 within the housing 105, the emitter window 120 is positioned within the housing 105 so that the emitter 127 is operable to transmit electromagnetic energy into the separator chamber 110. The receiver 137 is also positioned to receive electromagnetic energy from the separator chamber 110, transmitted through the receiver window 130. Thus, not only does this exemplary embodiment provide a self-cleaning function during use, but it also allows the user to clean the emitter and receiver windows 120, 130 in a way that may not be possible if the windows remained in the housing 105 or if the emitter 127 and receiver 137 were not separable from the separator chamber 110. Despite the foregoing, in alternative embodiments, the emitter 127 and/or receiver 137 may be attached to the housing 105, which may not be removable from the housing, or may be removed by disconnecting electrical circuits to the emitter 127 and/or receiver 137.

[39] In other embodiments of the invention, the emitter window 120 and/or the receiver window 130 may be formed from an elastic material. The use of a deformable window for the emitter window 120 and/or receiver window 130 may thus allow the window to be cleaned of dust and debris at the beginning and/or end of the operation of the vacuum. Either the receiver window 130 or the emitter window 120 may be formed from an elastic material, or both the receiver window 130 and the emitter window 120 may be formed from an elastic material. If the receiver window 130 or the emitter window 120 is formed from an elastic material, then the other may be formed as a projection into the separator chamber 110, shown above, or may be formed in another way.

[40] An example of a deformable window is show shown in Figure 7. Here, an elastic emitter window 710 is shown with an emitter 127. The elastic material allows electromagnetic energy from the emitter 127 to enter the separator chamber 110. For example, the elastic material may be substantially optically transparent, or may be transparent to the electromagnetic energy that the emitter 127 emits. The elastic material is molded in a "resting" position, such as shown in Figure 7, but is deformable into at least one "active" position, such as shown in Figure 8, in which the geometry of the window is different from the geometry in the "resting" position. In the shown embodiment, the window 127 assumes a generally parabolic shape extending outside the separator chamber 110 in the resting position, and generally the opposite shape in the active position. In other embodiments, however, other shapes may be used

[41] The window 710 may be formed of the same material as the separator chamber 110 and joined to the separator chamber 110 by adhesives, welding or the like. The window 710 also may be formed integrally with the separator chamber 110 as, for example, a relatively thin portion of the chamber wall. The window 710 alternatively may be formed of a different material as the separator chamber 110, and attached by any of the various known attachment means, such as ultrasonic welding, adhesives, fasteners, and the like. In Figure 7 and Figure 8, for example, the elastic emitter window 710 is formed of a separate, relatively thin piece of flexible material that is sandwiched between the separator chamber 110 wall and another piece of material 720 attached to the separator chamber 110. The elastic emitter window 710 may be attached on the outside of the separator chamber 110 wall or the inside of the separator chamber 110 wall. The elastic window 710 also may be formed from more than one layer of material. For example, the elastic material may be formed from one or more plastic layers (or one or more metal layers or other reflective layers, in the case of a flexible mirror as described below). In the shown embodiments, the window 710 comprises a generally continuous piece of material, but in other embodiments, the window 710 may comprise a rigid or relatively rigid central portion that is mounted in a flexible ring.

[42] In a preferred embodiment, the window 710 is adapted to deform from the resting position to the active position, then back to the resting position, many times. A suitable material is believed to be polyethylene terephthalate, which relatively strong, impact resistant and transparent. The rate at which the material transitions from the resting position to the active position, and vice versa, may be gradual or relatively quick. Preferably, the transition rate is relatively quick to help remove debris by rapidly accelerating and/or decelerating the window 710. [43] As shown in Figure 8, when the vacuum cleaner is in operation, the air pressure inside the separator chamber 110 drops below the air pressure outside the separator chamber 110. This pressure difference causes the elastic emitter window 710 to flex or deform into the separator chamber 110, placing the elastic emitter window 710 in the active position. Deformation of the elastic emitter window 710 into the separator chamber 110 may dislodge dirt or other debris adhering to the emitter window 710, and thereby clean the elastic emitter window 710 of some or all debris. If the emitter window 710 is configured to flex relatively quickly to the active position when the vacuum is activated, this may assist with dislodging any clinging debris. In addition, when the elastic emitter window 710 is in the active position, it forms a projection into the separator chamber 110, and the airflow around the projection may also clean dust and debris from the elastic emitter window 710 as explained above with respect to previous embodiments. The elastic emitter window 710 may remain in the active position while the air pressure inside the separator chamber 110 is less than the air pressure outside the separator chamber 110.

[44] When the vacuum is not in operation, the pressure inside and outside the separator chamber 110 reaches an equilibrium, and the elastic emitter window 710 returns to the resting position, shown in Figure 7. Dust or other debris that accumulates over the elastic emitter window 710 during operation may be dislodged when the elastic emitter window 710 returns to the resting position. In addition, the emitter window 710 may be retracted from the separator chamber 110 so that it does not obstruct the path of dirt when the separator chamber 110 is being emptied.

[45] While the foregoing embodiments describe the window 710 being displaced by the vacuum generated inside the separator chamber 110, such movement may be assisted or controlled by other means. For example, springs may be used to bias the window 710 into either position, and a mechanical device may be used to force the window 710 into either position. As one example of such an arrangement, a mechanism may be used to push the emitter 127 against the window 710 to move them both into the separator chamber 110 when the vacuum fan is operating.

[46] Of course, Figure 7 and Figure 8 may also represent the receiver window and the receiver 137, so that the receiver window may be formed from an elastic material, and may operate in a similar way as the elastic emitter window 710 shown in Figure 7 and Figure 8. In addition, the elastic emitter window 710 and/or the receiver window 130 may extend along the length of the separator chamber 110, as in, for example, Figure 6.

[47] Another exemplary embodiment of the invention is shown in Figure 9. In embodiments such as this, the emitter 127 and the receiver 137 may be positioned on the same side of a single window 910. A reflector 920 is provided to reflect the signal from the emitter 127 to the receiver 137. The reflector 920 may be formed from or coated with a material that reflects some or all of the electromagnetic energy emitted by the emitter 127. For example, the reflector 920 may be coated or formed from a mirrored material (such as a thin foil) that reflects visible or infrared light, if the emitter 127 emits visible or infrared light. The emitter 127 may emit electromagnetic energy through the emitter window 910 and into the separator chamber 110. Some or all of the electromagnetic energy may be reflected by the receiver window 920 back into the separator chamber 110. The receiver 137 may then receive the electromagnetic energy through the emitter window 910 (or, alternatively, through a separate window provided for the receiver 137), and may transmit a signal to suitable control circuitry to operate the vacuum as described in the preceding paragraphs. The emitter window 910 and/or the receiver window 920 may be fixed, as shown in Figures 1-6, or may be elastic, as shown in Figures 7-9 (Figure 9 shows the window 910 and reflector 920 in the resting position). The reflector 920 also may be located outside the separator chamber 110 behind a suitable rigid of flexible receiver window 920. For example, the reflector 920 may be located on the housing 105.

[48] It will be appreciated that embodiments of the devices disclosed herein may be used in any vacuum cleaner having a rigid dirt receptacle. For example, U.S. Pat. Nos. 6,613,129, 6,994,740 and 5,935,279 and U.S. Application No. 11/761,961 disclose upright vacuum cleaners having one or more cyclonic cleaning stages. The cyclones include a dirt receptacle formed by a rigid housing that surrounds or sits below the cyclone member. Embodiments of the present invention may be used in any of the various cyclone stages (e.g., in an upstream coarse particle separator or a downstream fine particle separator), or in a dirt receptacle located below the cyclone itself (in which dirt typically continues to circulate in a swirling manner). Embodiments of the present disclosure also may be used in horizontal or tilted cyclones, such as the cyclone shown in U.S. Pat. No. 6,502,277, in central vacuums using cyclone separators, or in other kinds or configurations of vacuum cleaner. All of the foregoing references are incorporated herein and form part of the present disclosure.

[49] The present disclosure describes a number of new, useful and nonobvious features and/or combinations of features that may be used alone, together, with upright vacuum cleaners, canister vacuum cleaners or other types of cleaning device, or in other ways. The embodiments described herein are all exemplary, and are not intended to limit the scope of the inventions in any way. It will be appreciated that the inventions described herein can be modified and adapted in various ways and for different uses, and all such modifications and adaptations are included in the scope of this disclosure and the appended claims.

Claims

We claim:

1. A sensor assembly for a vacuum cleaner, the sensor assembly comprising: a vacuum cleaner housing; a dirt separator chamber having a dirty air inlet, a clean air outlet, an emitter window, and a receiver window; an emitter mounted on the housing and positioned to emit electromagnetic energy through the emitter window; and a receiver mounted on the housing and positioned to receive electromagnetic energy through the receiver window; wherein the dirt separator chamber is removable from the housing, and at least one of the emitter window and the receiver window forms a projection into the dirt separator chamber during operation of the vacuum cleaner.

2. The vacuum cleaner of claim 1, wherein the emitter window and the receiver window form respective projections into the dirt separator chamber during operation of the vacuum cleaner.

3. The vacuum cleaner of claim 2, further comprising an emitter housing attached to the vacuum cleaner housing, the emitter being attached to the emitter housing.

4. The vacuum cleaner of claim 2, further comprising a receiver housing attached to the vacuum cleaner housing, the receiver being attached to the receiver housing.

5. The vacuum cleaner of claim 1, wherein the dirt separator chamber comprises a cyclone separator.

6. The vacuum cleaner of claim 1, wherein a fan is adapted to convey dirty air into the dirt separator chamber under positive pressure.

7. The vacuum cleaner of claim 1, wherein a fan is adapted to convey dirty air into the dirt separator chamber under negative pressure.

8. The vacuum cleaner of claim 1, wherein the projection comprises a raised surface that is discontinuous from the curvature of the separator chamber.

9. The vacuum cleaner of claim 1, wherein the projection comprises a lens.

10. The vacuum cleaner of claim 1, wherein the dirt separator chamber is removable from the vacuum cleaner housing without removing the emitter and the receiver.

11. A sensor assembly for a vacuum cleaner, the sensor assembly comprising: a vacuum cleaner housing; a dirt separator chamber having a dirty air inlet, a clean air outlet, an emitter window, and a receiver window, the dirt separator chamber being adapted to contain a generally cyclonic air flow; an emitter mounted on the housing and positioned to emit electromagnetic energy through the emitter window; and a receiver mounted on the housing and positioned to receive electromagnetic energy through the receiver window; wherein at least one of the emitter window and the receiver window forms a projection into the dirt separator chamber during operation of the vacuum cleaner, and wherein the velocity of the generally cyclonic air flow increases by at least about 10% at a location adjacent the projection.

12. The vacuum cleaner of claim 11, wherein the emitter window and the receiver window form respective projections into the dirt separator chamber during operation of the vacuum cleaner.

13. The vacuum cleaner of claim 11, wherein the velocity of the generally cyclonic air flow increases by at least about 40% at a location adjacent the projection.

14. The vacuum cleaner of claim 11, wherein the velocity of the generally cyclonic air flow increases by at least about 50% at a location adjacent the projection.

15. The vacuum cleaner of claim 11, wherein the velocity of the generally cyclonic air flow increases from about 10 meters per second to about 11 meters per second at a location adjacent the projection.

16. The vacuum cleaner of claim 11, wherein the velocity of the generally cyclonic air flow increases from about 10 meters per second to about 14 meters per second at a location adjacent the projection.

17. The vacuum cleaner of claim 11, wherein the velocity of the generally cyclonic air flow increases from about 10 meters per second to about 15 meters per second at a location adjacent the projection.

18. The vacuum cleaner of claim 11, wherein the boundary layer of the generally cyclonic air flow decreases by about 20% at a location adjacent the projection.

19. The vacuum cleaner of claim 11, wherein the dirt separator chamber is removable from the vacuum cleaner housing without removing the emitter and the receiver.

20. A sensor assembly for a vacuum cleaner, the sensor assembly comprising: a vacuum cleaner housing; a dirt separator chamber having a dirty air inlet, a clean air outlet, an emitter window, and a receiver window, the dirt separator chamber being adapted to contain a generally cyclonic air flow; an emitter mounted on the housing and positioned to emit electromagnetic energy through the emitter window; and a receiver mounted on the housing and positioned to receive electromagnetic energy through the receiver window; wherein at least one of the emitter window and the receiver window forms a projection into the dirt separator chamber during operation of the vacuum cleaner, and wherein the boundary layer of the generally cyclonic air flow decreases by about 20% at a location adjacent the projection.

21. The vacuum cleaner of claim 20, wherein the emitter window and the receiver window form respective projections into the dirt separator chamber.

22. The vacuum cleaner of claim 21, wherein the emitter window and the receiver window are rigidly formed with the dirt separator chamber.

23. The vacuum cleaner of claim 21, wherein the emitter window and the receiver window are movable with respect to the dirt separator chamber.

24. The vacuum cleaner of claim 20, wherein the dirt separator chamber is removable from the vacuum cleaner housing without removing the emitter and the receiver.