Pumps – Motor driven – Fluid motor
Reexamination Certificate
2000-04-18
2001-09-04
Walberg, Teresa (Department: 3742)
Pumps
Motor driven
Fluid motor
C417S395000
Reexamination Certificate
active
06283727
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to metering pumps, and more particularly, to a pneumatically operated metering pump.
BACKGROUND OF THE INVENTION
Metering pumps are used in a wide variety of industries. Typical uses include the addition of chemicals in liquid form to a reaction vessel or system or even simply for mixing purposes. Metering pumps are also extensively used in the food industry for metering ingredients into processes for the manufacture of processed foods. Other examples of their use will readily come to the mind of those skilled in the art.
Metering pumps also come in various types. One type of particular interest employs a diaphragm which is alternatively employed to draw the fluid to be pumped into a pumping chamber and then discharge the fluid from the pumping chamber. Usually, but not always, the diaphragm is cycled by a pressure fluid such as a pressurized gas or hydraulic fluid under pressure. Of the two, the latter is preferred because the incompressible nature of hydraulic fluid assures that its use as the pressurizing fluid in a diaphragm pump will cause the pump to operate as a positive displacement device throughout its cycle of operation. Consequently, the metering function of the pump is more accurate. Metering pumps today frequently employ pneumatic air cylinders to drive plungers to pressurize fluid to actuate a diaphragm to meter fluids.
Pumps of this sort work well for their intended purpose but systems in which they are employed may be unnecessarily bulky. Moreover, pumps of this type typically have a limited range of capacity. Where adjustment is provided within the range of capacity, the range is not sufficiently great as to encompass the entire spectrum of possible flow rates for which the pump might be used. Consequently, frequently a pump bought for a particular process because of its capability of operating within a capacity range needed for that particular process cannot be used in another materially different process where a completely different capacity range is required.
The present invention is directed to overcoming one or more of the above problems.
SUMMARY OF THE INVENTION
It is the principal object of the invention to provide a new and improved metering pump. More particularly, it is an object of the invention to provide a new and improved metering pump that is operated by hydraulic fluid under pressure.
An exemplary embodiment of the invention achieves the foregoing object in a metering pump structure including a housing having a pumping chamber within the housing. A diaphragm is moveable in the pumping chamber and separates it into a pumping side for receiving and discharging fluid to be pumped, and a pressurizing side for receiving hydraulic oil under pressure to move the diaphragm. An inlet is provided to the pumping side and includes a check valve for allowing a fluid to be pumped to flow into the pumping side while preventing flow from the pumping side through the inlet. Also provided is an outlet from the pumping side which includes a check valve which allows fluid to be pumped from the pumping side while preventing flow back into the outlet. A hydraulic pump is located in the housing and has a hydraulic piston containing hydraulic side. A port connects the hydraulic side to the pressurizing side of the diaphragm pump and a hydraulic oil reservoir is located in the housing and in fluid communication with the hydraulic side.
In one form of the invention, a bypass device is located in the housing and is connected to the port. The bypass device is operable upon operation of the piston to receive a predetermined amount of hydraulic oil, thereby providing a means of control over the amount of hydraulic oil delivered to the pressurizing side of the diaphragm pump.
In another facet of the invention, a cavity is located in the housing and the hydraulic pump includes a sleeve with an elongated bore removably secured in the cavity and a hydraulic piston reciprocally received in the bore and operated by an actuator for the pump. The use of the sleeve that is removably received within the housing and defines the bore of the hydraulic pump enables the hydraulic pump to be readily repaired in the event of wear caused by operation as well as allows the substitution of sleeves with different size bores receiving different size pistons so that the range of capacity of the pump can be substantially altered over a wide spectrum simply by selectively placing a sleeve with a desired bore size and a desired piston size therein into the pump.
According to still another facet of the invention, a second cavity is located in the housing and is connected to the port. A pressure relief valve is located in the second cavity.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.
REFERENCES:
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patent: 5860793 (1999-01-01), Muscarella et al.
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patent: 1-122131 (1998-05-01), None
Bean Robert F.
Borish David M.
Caspar Richard J.
Fastovsky L
Milton Bay
Walberg Teresa
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