Sprayer controller and method

Details Sprayer controller and method Sprayer controller and method

2000-12-07

2004-09-07

Mar, Michael (Department: 3752)

Fluid sprinkling, spraying, and diffusing

With selectively preset flow cutoff or initiating means

C239S550000, C239S551000, C239S562000, C239SDIG001

Reexamination Certificate

active

06786425

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a sprayer controller, and particularly to a sprayer controller which controls sprayer check valves and spray nozzles.
BACKGROUND TO THE INVENTION
Sprayers are used in agriculture and horticulture for applying chemicals and/or liquid fertilisers to growing crops, and for the treatment of harvested produce.
Generally, sprayers have a series of outlets across the width of the sprayer boom. Each outlet through which liquid is passed is provided with a check valve, commonly known as an Anti Drip Check Valve, and the check valve is generally equipped with a means to attach a nozzle or applicator on the downstream side of the check valve. Check valves are provided to prevent liquid flowing from the outlets when the said liquid is below a predetermined pressure. For example, a check valve may be set up so that liquid may not pass through the valve unless the liquid is at the intended working or application pressure, referred to hereinafter as the operating pressure.
The most common type of check valve used in agricultural and horticultural sprayers is a mechanical device and comprises a sealing diaphragm maintained against a sealing face by a compressed coil spring, the spring rate, or loading of which is determined by the pressure at which the valve is required to open and the surface area of the sealing diaphragm.
Other types of check valve are known, for example the check valve described in UK patent application no 9710834.4, and PCT/GB98/01546, the AirSTOP AS-200 valve available from KZCO Incorporated, the Air Chemsaver manufactured by Spraying Systems Co, and an air/spring operated valve described in FR-A-2515304.
Sprayer booms generally comprise a plurality of boom sections. This is so that the boom which may be 40 meters wide may be folded down to a width narrow enough to be transported on public roads. Also, it is convenient to be able to divide the boom into discrete sections which can be controlled individually. It is common for a sprayer boom to have a number of sections, and for the supply of liquid to each section to be controllable independently from the other sections. This is generally achieved by placing ball valves or other similar valves in the spray lines to each section so that the flow of liquid to any desired section can be shut-off, whilst the other sections continue to spray.
The types of valve used to control the flow of fluid to a boom section are relatively expensive, slow and heavy, as is the control equipment required to operate them. Increasing the weight of a sprayer boom is undesirable. Furthermore, it is only possible to control the flow of fluid to any one group of nozzles, i.e. all the nozzles on a particular boom section.
It would therefore be desirable to provide a sprayer controller which does not suffer from the disadvantages suffered by currently available equipment.
SUMMARY OF THE INVENTION
This invention includes aspects or features of applicant's copending U.S. patent application Ser. No. 09/424,568 of Matthew James Harold RAWLINGS titled “IMPROVEMENTS IN METERING DEVICES” filed Nov. 24, 1999, which is hereby incorporated by reference.
The invention provides a device for delivering a controlled dose of a fluid to an outlet from a fluid supply at an operating pressure, the device comprising an actively operable check valve, pressure exerting means to selectively exert first and second pressures on the check valve such that when one of the first and second pressures is exerted on the check valve the valve prevents the passage of fluid at operating pressure through the outlet, and when the other pressure is exerted on the check valve the valve permits the passage of spray fluid at operating pressure, characterised by signal generating means to generate a control signal characteristic of the fluid operating pressure, and control means for deriving at least one of the said first and second pressures from the said control signal.
The invention also provides a controller for a liquid spraying apparatus comprising at least one spray line provided with at least one outlet, each outlet being provided with an actively operable check valve, signal generating means to generate a control signal characteristic of the spray fluid pressure, pressure exerting means to selectively exert first and second pressures on the check valve, wherein at least one of the said first and second pressures is derived from the said control signal, wherein when one of the first and second pressures is exerted on the check valve the valve prevents the passage of spray fluid at operating pressure, and when the other pressure is exerted on the check valve the valve permits the passage of spray fluid at operating pressure.
The or each outlet may be provided with a nozzle or an applicator.
The first and second pressures may be derived from the said control signal.
The first pressure may be less than the spray operating pressure and the second pressure may be greater than the spray operating pressure. The first pressure may be 0.05 bar less than the spray operating pressure, and the second pressure may be 0.05 bar greater than the spray operating pressure.
The first and/or second pressures may follow the fluid spraying pressure, so that the first and/or second pressures is/are only fractionally greater or less than the spraying fluid operating pressure.
The pressure exerting means may comprise pressurised fluid, such as air, electrically or electronically powered actuators, or hydraulic actuators.
The said first and second pressures may be proportional to the said control signal. Alternatively, the said first and second pressures may be a differential of the said signal. The first and second pressures may be a fixed percentage of the spray fluid pressure irrespective of the actual spray fluid pressure.
The signal generating means may comprise a pressure transducer attached to the spray fluid line. The signal may be generated as a mathematical relationship to a measured parameter of the spray fluid circuit, the signal generating means comprising means to measure the said parameter.
When the said first pressure is exerted on the check valve, the said valve functions as a check valve, the check valve being actuated when the spray fluid pressure falls below a pre-determined value. Where the operator does not want spray fluid to flow through the nozzles until the pressure falls below the said predetermined value, he switches the controller so that the second pressure is exerted on the check valve which is higher than the spray fluid operating pressure, thereby providing substantially instantaneous shut off.
In the case of pneumatically operated check valves, low pressure and high pressure air lines may be provided, an exhaust being provided to permit the high pressure to decay, and preferably the low pressure air line supplies air to the check valves through the high pressure air line. Preferably, the controller limits the time during which the exhaust valve may be opened, thereby limiting the volume of air which can pass therethrough, and hence the fall in pressure in the check valves. The controller may comprise means to vary the time for which the exhaust valve is opened. In one embodiment opening the exhaust valve for 0.1 seconds allows the air pressure to decay sufficiently.
Air pressure in a pneumatic system may be controlled electronically or low-mechanically.
Preferably, air is distributed to the check valves, individually or in groups, through at least one manifold comprising a plurality of valves. The manifold valves may be actuated electrically, or electronically. Advantageously, a manifold may be provided in each of the high and low-pressure airlines.
Preferably, a 24 Volt DC supply is provided to power the electric and electronic components of the controller.
In one embodiment of the invention, the check valves are of the type where a force is exerted on a diaphragm against the spray fluid pressure to prevent flow thereof through the check valve. For these types of valve, when a pressure greater than the spray fluid oper

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