The removal of dirt and debris from streets, parking lots, airport runways, factory floors, and other similar paved surfaces, through the use of various types of street sweeping vehicles or factory sweeping vehicles, as may be the case, has been known for many years. As is well known in the industry, street sweeping vehicles, also known as mechanical street sweepers, employ a sweeping broom to remove dirt and debris from a surface and a conveying type elevating mechanism to lift the debris several feet up and deposit it into a hopper. Also, as is well known in the industry, factory sweeping vehicles, also known as factory sweepers, employ a sweeping broom to remove dirt and debris from a surface and sweep the debris several feet up and deposit it into a hopper. For the sake of brevity, clarity and simplicity, such vehicles will be generally referred to in this document as surface sweeping vehicles.
In surface sweeping vehicles, a pair of counter-rotating brushes sweep dirt and debris inwardly to underneath the central area of the sweeper and an elongate cylindrically-shaped sweeping broom that rotates about a horizontal axis sweeps the dirt and debris forward up and onto a conveyor. The conveyor deposits the dirt and debris into a hopper for subsequent controlled dumping from the hopper. Such mechanical broom sweepers can remove large amounts of dirt and debris from a paved surface quite quickly and can generally remove large pieces of debris quite readily. However, they cannot contain fine particulate matter that has become airborne, without the use of water for dust suppression. The use of water is undesirable as it creates two problems. A covering of wet dirt remains on the surface behind the surface sweeping vehicle. During the warm months, when the water in this wet dirt evaporates, significant amounts of dried small particulate matter from the wet dirt become air borne. Also, water cannot be used in cold winter months because the water tends to freeze on the surface being swept, thus creating unsafe conditions, and tends to freeze in tank, lines and water pipes.
It is widely accepted in the industry that the containment of dust generated during the street cleaning operation is extremely difficult, especially the containment of dust having a particle size under ten microns, without using water. Virtually all street sweepers--that is to say mechanical street sweeping vehicles employing sweeping brooms as the primary means for removing dirt and debris from a road surface--have an inherent problem with containment of dust, especially dust having a particle size under ten microns. With street sweeping vehicles, it is common to use water for dust suppression. However, water can be used only during warm weather when the water will not freeze, and thus, such sweepers are often avoided altogether in many colder climates. Moreover, after a wet road surface has been swept by a sweeping broom, the wet road surface dries and leaves behind a residual fine dust that ultimately becomes airborne, commonly in the form of very fine dust having a particle size under ten microns, which is highly unacceptable.
Recently, it has become increasingly important for environmental reasons to not just fully remove dirt and debris during a street cleaning operation, but to remove dust and other particulate matter, especially particles less than about ten microns. In many jurisdictions, there are strict environmental laws pertaining to the removal and containment, during a street cleaning operation, of particulate matter having a size of less than ten microns, which is essentially breathable particulate.
Some mechanical type street sweeping vehicles employ a rotating broom that throws dirt and debris into a "squeegee" type elevator for deposit into a hopper. The elevator overthrows the dirt and debris into a hopper behind the elevator. The filtration system is located within the hopper, directly over the entire volume of the hopper. Air from the hopper is drawn upwardly through the filters, thus always creating a negative pressure within the hopper, elevator, and sweeping broom areas, and is expelled through a small additional filter to the atmosphere. During use, the filters trap dust and fine debris from the air stream created by the fan. A vibrating mechanism shakes the filters to shake loose the trapped dust and debris and deposit it into the hopper. However, since the air stream is continuously flowing at an aggressive pace through the filters, the trapped dust and debris can tend to clog the filters. In order to properly clear the filters completely, the sweeping operation must be stopped, and the filters vibrated until they are clear. Often, additional cleaning and maintenance of the filters may be necessary.
Moreover, due to the inherent positioning of the filter in the hopper, such filters are susceptible to moisture carryover, which can lead to clogging of the filters, thereby possibly causing cessation of dust control.
The only mechanical street sweeping vehicles that can employ an auxiliary debris suction hose to facilitate the supplemental suctioning of debris, must first stop their street sweeping operation due to their inherent design and operating characteristics.
It is an object of the present invention to provide a dust controlling apparatus for use in a mechanical surface sweeping vehicle, which dust controlling apparatus substantially precludes dust that is generated during a street cleaning operation from being expelled to the atmosphere.
It is an object of the present invention to provide a dust controlling apparatus for use in a mechanical surface sweeping vehicle, which dust controlling apparatus substantially precludes dust that is generated during a street cleaning operation from being expelled to the atmosphere, without the use of water for dust suppression.
It is another object of the present invention to provide a dust controlling apparatus for use in a mechanical surface sweeping vehicle, which dust controlling apparatus substantially precludes dust that is generated during a street cleaning operation, and has a particle size of less than ten microns, from being expelled to the atmosphere.
It is a further object of the present invention to provide a dust controlling apparatus for use in a mechanical surface sweeping vehicle, which dust controlling apparatus substantially precludes dust that is generated during a street cleaning operation from being expelled to the atmosphere, during the cleaning in both wet and dry street conditions.
It is yet another object of the present invention to provide a surface sweeping vehicle that can suction dust and various forms of debris while sweeping a surface with a sweeping broom.
It is yet another object of the present invention to provide a surface sweeping vehicle having a dust and debris separator that does not become clogged with moist debris.