Patent Application
20110041782
The present invention is directed to an apparatus for controlling pests among other uses, particularly vegetation or weeds using a blast of hot air and steam, hot water or hot water vapor. In particular, the present invention is directed to an apparatus having various features such as valve arrangements, output nozzles, etc. to maximize operation of the apparatus.
The control of unwanted pests, such as vegetative growth, is utilized to improve aesthetic appearance as well as removing the noxious pests or vegetation. In the past, one of the most common methods of controlling such unwanted growth was through the application of pesticides to the vegetation. Such pesticides, particularly herbicides, were commonly applied by spraying a liquid herbicide or through spreading of powders or granules. However, in recent years the use of herbicides has met with increased resistance owing to environmental, health and safety concerns. Herbicides can contaminate soil, air, groundwater and desirable vegetation and may cause health problems to those exposed to such chemicals. In view of these problems, the use of herbicides has been restricted or in some cases completely banned in many jurisdictions.
As environmental concerns are reducing the use of pesticides, and the prohibitive costs and inefficiencies of manual weeding become apparent, the use of heat and/or steam for vegetation control is gaining popularity. Heat coagulates plant protein, destroying plant cells, disrupting vascular flow and respiration. Also waxy protective leaf coatings are removed, promoting dehydration and death of the plant. Studies have shown that exposure to 80 C. (176 F) for one second can kill vegetation. Also steam or moist heat is superior to flame or dry heat for weeding as damp air transfers heat more readily, and is easier to apply in a downward direction (hot, dry air rises and diffuses faster). Steam or moist air is less likely to cause accidental fires and thus is safer than flame or dry heat.
Recently, the use of heat to kill unwanted vegetation has been utilized and a number of apparatus to apply heat, generally in the form of hot water or steam have been proposed. Examples of such apparatus are shown in U.S. Pat. Nos. 5,385,106, 5,430,970, 5,927,601, 5,946,851, 6,029,589, 6,047,900, and 6,321,037, PCT Patent Application WO 00/22926 and New Zealand Patent Application 237,524 among others.
In my previous U.S. Pat. No. 7,100,040, the disclosure of which is incorporated herein by reference, an apparatus for directing steam, hot water or hot water vapor and hot air onto a target area was described. The apparatus included an applicator wand, having a steam generator immediately adjacent the target area within a steam head at one end of the applicator wand. The applicator wand also included trigger controls to allow for a continuous flow of water to a flash boiler located in the steam head as part of the steam generator. However, the valve arrangements illustrated in that patent were fairly complex with a number of divergent paths and individual valves.
While the apparatus described in U.S. Pat. No. 7,100,540 was effective for weed control, particularly on hard surfaces, the efficiency of operation of the apparatus was found to be less than that of traditional herbicide application.
There thus remains a need for a steam generating apparatus for pest control in particular weed control having a simpler design and operation as well as having increased efficiency compared with the prior apparatus.
In one aspect of the invention, there is provided an apparatus for generating at least one of steam, hot water and hot water vapor along with air heated by a burner for application to unwanted vegetation. The apparatus comprises a wheeled cart supporting a water container, a control module, a holder for an applicator wand and a fuel container. The applicator wand comprises a holding means and an applicator head coupled to the holding means. The applicator head comprises a housing, an inlet and an outlet to define a cavity to accept a flash boiler adjacent the outlet, the flash boiler comprising a steam generator and a burner for heating the steam generator. A first elongate hose connects the water container to a first control located on the applicator wand, the first control controlling and supplying a flow of water to the steam generator, and a second elongate hose connects the fuel container to a second control located on the applicator wand, the second control controlling and supplying a flow of fuel to the burner. Both the first and second controls are controlled by a single switch, such that when said switch is activated, fuel and water are supplied essentially simultaneously to said flash boiler and a blast of heated air and at least one of steam, superheated steam, hot water and hot water vapor is urged from the outlet to the unwanted vegetation. The control module of the wheeled cart includes a water pump to supply water to the applicator wand from the water tank, a source of energy for the water pump and control and feedback circuitry and displays to allow an operator to monitor the operating parameters of the apparatus.
In another aspect of the invention, the apparatus is provided with a plurality of flash boiler in a broad applicator head to provide a wide application to the unwanted vegetation.
In another aspect, the present invention provides for a flow control and flush valve for a steam generating apparatus for weed control, which allows for a simple means of controlling the volume of water flowing through the system. The flow control valve comprises a first fixed elliptical orifice and a second rotating elliptical orifice. The center of rotation of the second elliptical orifice is located adjacent one end of the orifice. The rotation of the rotating orifice varies the overlapping area between the fixed orifice and the rotating orifice to allow for control of the volume of water flowing through the overlapping orifices.
In another aspect of the invention there is provided a trigger control valve having a bypass channel such that a small flow of fluid passes through the valve when the valve is in the closed position.
In a further aspect of the invention the trigger control valve is provided with an inlet and outlet and a spring biased poppet, which seals the outlet when the valve is in the closed position. The sealing surface of the valve against which the poppet rests is provided with a channel to allow for a low flow of water in the closed position.
In yet another aspect of the invention there is provided a steam nozzle for a steam generating apparatus for weed control. The steam nozzle aids in diffusing the steam and accelerating the airflow through the steam generating apparatus. The steam nozzle comprises an inlet and a plurality of outlets to provide for the diffusion of the steam from the steam generating apparatus.
In yet another aspect of the invention, the steam nozzle is centrally mounted within the outlet of the steam generating apparatus by a plurality of spacers or fins located between the exterior of the steam nozzle and the interior wall of the steam head of the steam generating apparatus.
In yet another aspect of the invention, the steam generating apparatus is provided with an air blower to increase the volume of air flowing through the steam generating apparatus to increase the combustion of the fuel used to heat the flash boiler, as well as to increase the output of steam and hot air from the steam generating apparatus.
In yet another aspect of the invention, the steam head containing the steam generating apparatus is provided with an outlet having an elliptical or oval shape to concentrate the steam and hot air to the target area.
In yet another aspect of the invention, the steam head is provided with a floating inner barrel. The inner barrel is attached to the outer barrel at only one end, preferably the exit end. It fits snugly but floats within the sleeve of the outer barrel at the other end—the intake end. The allows for heat expansion as the inner barrel lengthens further than the outer barrel due to higher temperatures to which it is exposed.
Preferred embodiments of the present invention are illustrated in the attached drawings in which:
A preferred embodiment of the apparatus of the present invention generates a blast of hot air and at least one of steam, hot water or hot water vapor from an applicator head containing a flash boiler heated by a burner, the flash boiler being located in the apparatus adjacent to the outlet to apply the blast to a target area. The apparatus is useful for many applications requiring a blast of hot air and steam, hot water or hot water vapor such as controlling pests through the application of hot air and steam, hot water or hot water vapor directly to the pests only as needed. Other possible uses include a steam cleaner for surfaces not susceptible to heat damage or for heat activation of other materials such as detergents or cleansers or other uses as set out below. Preferably, the apparatus is for controlling pests, particularly unwanted vegetation; however, the apparatus may also be used to control other pests, such as insects, microbial infestations, invertebrates such as mollusks or mussels, etc. The apparatus preferably has an applicator wand for delivery of the heat and steam, hot water or hot water vapor to the vegetation and is characterized by the wand being provided with an applicator head having a steam generator, preferably a burner assembly and a flash boiler, located at the end of the wand, adjacent to or in close proximity to the target area of application. The apparatus has a water supply and fuel supply for the burner and steam generator, the water and fuel being supplied to the burner and steam generator through suitable hoses.
A preferred embodiment of the apparatus of the present invention, is illustrated in
The applicator wand 10 is designed for one hand operation and consists of a forearm brace 40, a pistol style grip 42 with trigger controls, and a suitable dimensioned metal tube or pipe 44 carrying the fuel and water lines and connected to the applicator head 36 containing the burner assembly and steam generator. The applicator head 36 preferably has an insulated, reflective, metallic wall 46 to maximize and focus heat production. The applicator head 36 is dimensioned to produce the desired steam and heat output while being able to be manipulated by the user. Preferably, the applicator head 36 is tubular having an inner diameter of between about 2 and 6 inches, more preferably about 2 to 4 inches, and a length of between about 12 and 30 inches, more preferably about 18 to 24 inches, depending upon application, burner size and desired steam and hot air output.
Referring to
The water hose 30 is connected to a trigger control valve 64 controlled by the trigger control 56. The trigger valve 64 provides reduced water flow in the “STAND-BY” position, and permits water flow in the “ON” position as will be described in detail below. From the trigger control valve 64, a water line 66 is attached to a flow control valve 68 designed to set the flow of water to the flash boiler as will be described below. From the flow control valve 68, the water travels down a water line 70 along the applicator pipe 44 to a flash boiler arrangement within the applicator head 36. The details of the flash boiler arrangements are set out in U.S. Pat. No. 7,100,540, the disclosure of which is incorporated herein by reference.
In many of the applications where steam is used for pest control, it is desirable to provide for a continuous flow of water to the flash boiler, even in STAND-BY mode. By providing a small trickle of water to the flash boiler, the response time when the switch is pressed to the ON position is reduced and the life of the flash boiler is extended. The continuous small flow of water is provided by a valve arrangement having a suitable means to feed a small amount of water to the flash boiler at all times. One means of accomplishing this is utilizing the trigger control valve 64 and flow control valve 68 of the present invention, both of which are “leaky” valves as will be explained below.
The details of the preferred embodiment of the trigger control valve 64 of the present invention are illustrated in
In order to provide for the “leaky” or slow flow characteristic of the trigger control valve 64, sealing surface 78 is provided with a leak channel 92 which allows for a low flow of water through the channel 92 when the poppet 82 is in the closed position. As there may be some collection of debris in the leak channel 92, a further cutout 94 may be provided to flush any debris from the leak channel 92 when the poppet 82 is opened.
In some applications, it is desirable that a higher proportion of hot air to steam and hence higher treatment temperatures be applied, which can results in a higher rate of operation. In other applications such as more flammable situations, a higher proportion of steam and hence a lower treatment temperature is desired. The proportion of steam to hot air in the output of the apparatus of the present invention can be adjusted by the amount of water being provided to the flash boiler. The higher the amount of water provided to the flash boiler, the more steam generated as the water is converted to steam. Thus by adjusting the flow rate of the water to the flash boiler, the relative amounts of steam and hot air in the output of the apparatus can be regulated.
There are a number of ways in which the flow of water to the flash boiler and hence the ratio of hot air and steam in the output can be adjusted. This can be accomplished by providing a flow control valve 68 with a variable adjustment to allow for complete control over the flow of water. In this way, the operator can select the flow rate to provide the optimum ratio for a particular application.
In the preferred embodiment, the flow control valve 68 is a face seal rotary valve with elliptical orifices. As shown in
Face seal plate 104 is provided with a second elliptical opening 114 which in the open maximum flow position shown as D generally aligns with the first elliptical opening 100 on the recessed surface 98 of the outlet 96. As illustrated in
For most applications, the actual ratio of steam to hot water may not be critical, rather the presence of a certain amount of hot water in the output may be advantageous. It is therefore preferred if a multi-position switching means is provided to allow the operator to select a high water, high steam and perhaps intermediate positions. For example, the flow control valve 68 is calibrated for the desired output settings and the adjustment knob 102 of the valve 68 is provided with markings to allow the user to easily select the desired setting. Thus the valve 68 is calibrated for a high steam output and the adjustment knob position for this setting is indicated. Similarly, a high water setting is determined and the adjustment knob position indicated. One or more intermediate positions between these two settings may be also provided if desired.
In another aspect of the present invention, the flash boiler of the steam generating apparatus is provided with a steam nozzle arrangement as shown in
It is preferred if the steam nozzle 120 is centrally located in the lower opening of the applicator head 36. In order to achieve this, mounting spacers or fins 128 are provided attached to the body of the steam nozzle. Spacers or fins 128 are sized to fit within the opening of the applicator head 36 to maintain the steam nozzle in the desired position within the applicator head 36. The embodiment illustrated in the figures has four such spacers or fins 128, however fewer or more such structures may be provided depending upon the size and configuration of the applicator head.
In another aspect of the present invention, a new design for the applicator head 36 has been developed as illustrated in
Another improvement to the steam generating apparatus is the provision of an air blower 58 to increase the volume of air flowing through the steam generating apparatus to increase the combustion of the fuel used to heat the flash boiler, as well as to increase the output of steam and hot air from the steam generating apparatus. Such an arrangement has been illustrated in
A further embodiment of an applicator head of the present invention is illustrated in
A broad head applicator head for providing a wide treatment area is illustrated in
The broad head applicator head 300 may be attached to the front of a cart similar to that as described above, or as illustrated in
The broad head applicator head is preferably provided with a wheel or skid at the front thereof to space the enclosed box slightly above the surface to be treated to allow the broad head applicator head to pass over the surface to be treated. This embodiment of the applicator head is of particular use on gravel and interlocking paths and generally open space, non-linear weed control.
The present invention provides for numerous improvements in steam generating apparatus for pest control, resulting in more efficient operation. The improvements make the operation of the apparatus easier for the user and result in some cases in an apparatus having a reduced weight which also increases ease of operation.
In addition to the uses of the various improvements to steam generating apparatus as described above, it will be appreciated that certain of the described components may have broader application. For example, the “leaky” valves described above have utility in other applications where it would be advantageous to have a continual low flow of fluid through the valve at all times. In particular, applications where the valves controlling the fluid flow are exposed to extremes in temperature, particularly temperatures below freezing could benefit from such valves. The low flow rate at all times through the valves could prevent the fluid within the lines or the valves itself from freezing and causing potential damage. Other uses for these and other components described above will be apparent to those skilled in the art.
Although various preferred embodiments of the present invention have been described in detail, it will be appreciated by those of skill in the art that variations may be made thereto without departing from the spirit of the invention.
| Number | Date | Country | |
|---|---|---|---|
| 61168210 | Apr 2009 | US |
