Fluid handling – Systems – With pump
Reexamination Certificate
2000-07-27
2001-11-13
Rivell, John (Department: 3753)
Fluid handling
Systems
With pump
C366S181800, C366S182200
Reexamination Certificate
active
06314996
ABSTRACT:
BACKGROUND OF THE INVENTION
Foam marking systems are well known in the agricultural industry for marking passes through a field so that subsequent passes will not overlap or be spaced from previous passes. Such conventional foam marking machines utilize a large tank wherein the foaming agent is mixed with water to create a foam solution. The solution is then mixed with air to produce a detergent-type foam which is dropped off the end of an agricultural sprayer boom periodically to leave a path to follow on the next pass through the field. The foam path prevents overlapping or gaps, both of which are detrimental to crop yield.
Air, water and foam concentrate are the three primary components for foam generation. In most prior art systems, the air supply is constant. The mixed solution for water and foam concentrate typically ranges between 32:1 to 256:1. This mix ratio is dependent upon several variables to achieve optimum foam delivery, including ambient temperature, water temperature, water hardness, and foam concentration.
Several problems exist with conventional prior art foam marking systems. First, the systems require a large, usually heavy, tank mounted on the sprayer to hold the mixed water and foam solution. Secondly, the operator must mix the foaming agent in water to achieve the desired quality of foam solution, which is often difficult due to the variables which affect the foam quality. Also, many operators do not carefully measure the water and foam concentrate when making the solution, resulting in foam solutions which may be too stiff or too wet for a particular application.
Another problem in prior art foam marking systems which utilize pre-mixed or pre-diluted foam solutions is the use of hard water. In such pre-mixed solutions, the calcium and magnesium ions present in most water sources react with certain ingredients in the foam concentrate, thereby precipitating active ingredients which reduce the performance of the foam marking system. The precipitation effects increase gradually over time, making the pre-mix or pre-dilute systems unsatisfactory, particularly as the time between mixing the solution and generating the foam increases.
Accordingly a primary objective of the present invention is the provision of an improved foam marking system which overcomes the problems of the prior art.
Another objective of the present invention is the provision of a foam marking system wherein the sprayer carriers separate smaller tanks for the foam concentrate and water, with a small mixing chamber to provide a desired mixed solution.
A further objective of the present invention is the provision of a foam marking system wherein the mix ratio is maintained constant regardless of the volume of foam generated.
Another objective of the present invention is the provision of a foam marking system wherein the foam solution is mixed on the go in the field as the sprayer is operated.
Another objective of the present invention is the provision of a foam marking system wherein the mixing of the water and foam concentrate is adjustable via separate pumps for each liquid, with each pump being controlled with a pulse width modulation electronic circuit.
A further objective of the present invention is the provision of a foam marking system which maintains a linear relationship between the water and foam concentrate at all foam output levels.
Another objective of the present invention is the provision of an improved method of generating a foam marker.
A further objective of the present invention is the provision of an improved foam marking system which eliminates or avoids the precipitation effects of hard water interacting with foam concentrate.
Still another objective of the present invention is the provision of a foam marking system which enables the operator to vary the composition of the resultant foam to meet the needs of the operating conditions at the time of spraying.
These and other objectives will become apparent from the following description of the invention.
SUMMARY OF THE INVENTION
A foam marking system is provided with a fresh water tank and a separate foam concentrate tank. A mixing chamber is also provided for receiving and mixing water and foam from each of the tanks, as supplied by first and second pumps, respectively, to create a foam solution. The pumps are adjustable and controlled by separate pulse width modulators. The primary control sends an output signal to both the water pump and a slave control unit, which in turn sends a signal to the foam concentrate pump. Thus, the marking system maintains a linear relationship between the water and foam concentrate at all foam output levels, since the slave control unit for the concentrate pump operates as a function of the master control for the water pump.
REFERENCES:
patent: 3164374 (1965-01-01), Ralph
patent: 3319937 (1967-05-01), Wilson et al.
patent: 3424439 (1969-01-01), Baker
patent: 3912234 (1975-10-01), Peter
patent: 4090695 (1978-05-01), Stone et al.
patent: 4296875 (1981-10-01), Borglum
patent: 5031834 (1991-07-01), Simpson
patent: 5133500 (1992-07-01), Simpson
Borglum Anthony R.
Borglum Richard P.
Cerwinske Corey W.
Richway Industries Ltd.
Rivell John
Zarley McKee Thomte Voorhees & Sease
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