Patent Application
20130276262
Not applicable.
The present invention relates generally to vacuum cleaners, and in particular to vacuum cleaners used for picking up fine materials, which may include ash.
The applicants developed a new vacuum for use in vacuuming ashes. It includes a safety feature that was developed to reduce the risk of fire in the event a user uses the device with hot ashes, but may offer pre-filtering advantages in a broad range of vacuum cleaners.
The vacuum cleaner disclosed in U.S. Pat. No. 4,355,434 is designed for use on ashes. The product has a metal screen cage (33) that is wrapped around the filter (30) to protect the filter from sparks/smoldering ashes. The use of expanded metal cages to hold a filter in place is common in the art, with a bolt and wing nut combination that passes through the filter often used to enable the user to remove the screen cage from the lid and simultaneously free the filter for cleaning or replacement.
The new arrangement not only reduces the risk of fire in the event that the product is used to pick up hot ashes, but is also less messy to use and has been found to provide better support and pre-filtering than conventional filter arrangements.
Like prior known vacuum cleaners used for vacuuming ashes, the new vacuum cleaner has a receptacle for debris, a lid that fits on the receptacle, a screen cage that is attached to the lid and extends into the receptacle, and a vacuum source that develops an airflow path that leads into the interior of the receptacle, through the screen cage, to a replaceable filter.
Unlike in previously known vacuum cleaners used for this purpose, the screen cage is permanently attached to the lid, and the replaceable filter is mounted to a power head that can be removed from the lid while the lid remains attached to the receptacle, enabling the filter to be removed and replaced while the lid and screen cage remain attached to the receptacle. The new vacuum cleaner also has a thermal cutoff that shuts the vacuum cleaner off when the temperature of air in a part of the flowpath exceeds a limit.
Unlike previously known screen cages, the new screen cage has multiple layers of screens with different screen sizes. Its primary screen has apertures in the range of 0.05-0.3 mm. It has an inner support that has greater rigidity than the primary screen and has apertures larger than those of the primary screen: in the range of 0.3-2.0 mm. The new screen cage also has an outer screen that is made of a different material than the inner support and has greater rigidity and larger apertures.
The invention may be better understood by referring to the accompanying drawings, in which:
As seen in
As seen in
When the vacuum cleaner is turned on, the vacuum source creates a vacuum that draws dirt-filled air into the receptacle 18 through the inlet 20. An optional deflector 42, preferably made of die cast metal such as aluminum, is mounted adjacent the inlet and directs the incoming airflow to bend 90 degrees and swirl around the perimeter of the receptacle. Dirt and debris falls out of the swirling airflow and collects in the bottom of the receptacle.
The vacuum source 35 draws the rest of the airflow in the receptacle 18 through a screen cage 25 before it reaches the replaceable filter 30. It is preferred that the screen cage be generally cylindrical in shape (as seen in the drawings). As best seen in
It is preferred that the primary screen have apertures in the range of 0.05-0.3 mm. The illustrated primary screen is made of 70×70 mesh of type 304 stainless steel with 0.0065″ wire diameter, providing 0.008″ openings.
It is also preferred that the screen cage 25 have one or more additional layers of screen made of a different material. One preferred layer, best seen in
Another preferred layer is an outer screen 55 that has larger apertures than the primary screen 50, providing further pre-filtering of the airflow. Preferably, the outer support has apertures in the range of 0.3-2.0 mm. In the illustrated example, the outer screen is made of the same 16×16 mesh of galvanized steel with 0.0018″ wire diameter used for the support. Using the same material for both a support and an outer screen can provide efficiency advantages.
The illustrated screen cage is made by rolling all three layers of screen together into a cylinder that is approximately 6¾″ tall and has an outside diameter of approximately 6″. The layers are simultaneously joined with a row of spot welds. The cylinder is then attached, such as by spot welding, to an upper ring 57 and to a lower plate 59. The illustrated upper ring and lower plate are made of 0.6 mm thick electro zinc coated deep-drawn quality cold rolled steel, though other materials can also be used. This method of manufacture is particularly useful and efficient.
The assembled screen cage 25 is attached to a lid 60 on the receptacle 18, and preferably extends into the receptacle. In this case, the inlet 20 is on the lid and the lid is itself removable from the rest of the receptacle. However, other arrangements are possible, and it is not essential that the inlet be on the lid or that the lid be separable from the rest of the receptacle.
In some cases, it may be preferred that the screen cage 25 is permanently attached to the lid 60. This can be done, for example, by mechanically fastening the upper ring to the lid, or in any of a variety of conventional ways. In other cases, it may be advantageous to use a screen cage that can be removed from the lid by the owner for cleaning or replacement.
The power head 14 is detachably mounted to the lid 60, covering an aperture 62 in the lid that opens to the interior of the screen cage 25. In this example, a short plastic tank spacer 65 is provided on the lid, ensuring a good fit against a lower rim 67 on a lower housing part 70 of the power head. The replaceable filter 30 extends downwardly from the power head and, when the power head is mounted to the lid, extends through the aperture into the interior of the screen cage, nesting within the screen cage. As seen in
In the illustrated example, conventional latches 75 (best seen in
In the illustrated vacuum cleaner 10, an automatically resetting thermal cutoff 75 is provided in the flowpath between the impeller 39 and the exhaust 40. This thermal cutoff detects the temperature of air in that part of the airflow path and shuts the vacuum cleaner off when the temperature exceeds a limit. This provides additional fire protection in the event that the vacuum cleaner is used to vacuum hot ash. In this example, the thermal cutoff is mounted on a second plastic housing part 80
This description of various embodiments of the invention has been provided for illustrative purposes. Revisions or modifications may be apparent to those of ordinary skill in the art without departing from the invention. The full scope of the invention is set forth in the following claims.
