Two-Component Metering Pump

This invention relates to variable diaphragm type metering pumps, and more particularly, to an adjustable pump which is well adapted for accurately and adjustably supplying metered quantities of a two-component product.

One common usage of metering pumps is in the measuring of components of multi-component products, such as paints, resins, and floor coverings, and also in adding small quantities of concentrate to water as in fertilizing and spraying herbicides onto crop fields.

It is readily apparent that with such widely different usages, numerous requirements are encountered as to make very substantial demands upon the capability of the pump.

Although a two-component metering pump has been known previously, inherent construction features clearly limit the usefulness in certain situations. Metering capability has been provided by mechanically limiting the return stroke of the piston. See U.S. Pat. No. 1,612,727. In limiting the return stroke of the piston, the piston encounters a mechanical stop which suddenly absorbs the inertia of the piston, any assemblies connected with it, and the diaphragm-operating hydraulic fluid or oil. The revolving cam will initially lift off the stopped piston and then impact the piston again to suddenly start it into motion. Depending upon the shape of the cam and the time in each cycle at which the cam reengages the piston, the repeated impact of the cam against the piston and the repeated impact of the piston against the stop can create substantial vibration in the pump.

Other single component diaphragm type metering pumps have used other types of mechanisms for varying the pumping rate. For instance, one pump has a port in the piston for suddenly releasing pressure in the cylinder at the end of the pressure stroke, as the piston port passes by the end of a stationary and adjustable rod, see U.S. Pat. No. 3,285,182. Another pump varies the length of stroke of the piston by varying the eccentricity of the driver for the piston, see U.S. Pat. No. 3,374,750. Such varying of eccentricity involves complicated mechanisms; and relying upon relief of developed pressure at the end of the pressure stroke requires a rather complicated mechanism and the developing of vacuum pressures on the return stroke which cause related complicating problems.

Still other diaphragm type pumps show the basic separation between the hydraulic fluid pumped by the reciprocating piston and the other liquid pumped by the diaphragm. Excess pressure under certain circumstances is relieved in various ways in these pumps and of course refilling of the cylinder after such relief is necessary. See U.S. Pat. Nos. 2,578,746; 3,075,468; 3,254,845; and 3,680,981.

An object of the invention is to provide an improved two-component diaphragm pump to simply and effectively vary the quantities of components pumped over a wide range.

Another object of the invention is to provide in a two-component tandem diaphragm pump, a simple and readily variable control apparatus for changing the proportioning of the pumped liquid.

Still another object of the invention is the provision of a two-component tandem diaphragm pump and drive therefor adapted to vary the quantities of both liquids being pumped and also the proportion of the liquids as compared to each other.

A further object of the invention is the provision in a variable diaphragm pump. of an adjustment control and proportion-varying apparatus facilitating extremely accurate adjustments of the quantities pumped and which adjustments are highly repeatable.

Still another object of the invention is to provide a tandem diaphragm pump incoporating long life and effectively sealing pumping diaphragms which resist the deteriorating effect of liquids being pumped.

An additional object of the invention is the provision of a two-component proportioning diaphragm pump which provides for relief of the pressures of the pumping hydraulic fluid when flow of the pumpage is suddenly stopped, and prevents relief of any of the pressure of the hydraulic fluid during normal operation and flow of the pumpage to the dispensing nozzle.

A principal feature of the present invention is the provision of the two-component proportioning pump having tandem diaphragm pumps each operated by a separate piston pump with a common drive and an adjustable sleeve forming the cylindrical wall of one of the piston pumps in order to obtain the desired proportioning at the diaphragm pumps.

Another principal feature of the invention is the provision of a two-component proportioning pump utilizing tandem diaphragm pumps and piston pumps to operate the diaphragm pumps, one of the pistons operating in an adjustable sleeve with a refill port therein communicating directly with the common reservoir of pumping oil, the sleeve extending well into the reservoir with its exterior exposed to the reservoir while the piston extends into the interior thereof.

Another feature of the present invention is the provision of a variable speed characteristic in the two-component proportioning pump for controlling the quantity of pumping by both of the diaphragm pumps and with control apparatus for changing the relative pumping capabilities of the two diaphragm pumps to obtain correct proportioning of the pumped liquid.

Another feature of the invention is the provision of a double thread adjusting arrangement on an adjustable sleeve forming the cylinder of a piston pump operating the diaphragm pump according to the present invention.

Another feature of the present invention is the provision of the two-component proportioning pump utilizing tandem diaphragm pumps which utilize diaphragms with a sandwich construction of Buna-N rubber at the oil side of the diaphragm and Teflon at the pumping side of the diaphragm to resist deteriorating effects of liquids being pumped and wherein the sandwiched diaphragm has annular inner and outer sealing beads confined in grooves in the housing and the piston-operated stem attachment.

Still another feature of the invention is to adopt a two-component proportioning pump utilizing diaphragm pumps, to be driven by either a rotary eccentric or by another fast acting reciprocating drive, such as a piston type pneumatic motor.

A principal advantage obtained by the present invention is the accurate varying of the proportions of the quantities of liquid being pumped over a wide range and permitting the quantities of both of the liquids to be varied considerably and without allowing any undesired vibrations to be set up in the pumping assembly, regardless of the pressures and speeds involved. With the present invention the quantities being pumped may be readily adjusted and repeated.

FIG. 1 is a diagrammatic plan view illustrating the invention.

FIG. 2 is a longitudinal section view taken on an upright plane as indicated approximately at 2--2 in FIG. 3.

FIG. 3 is a longitudinal section view taken approximately at 3--3 in FIG. 2.

FIG. 4 is an enlarged detail section view taken approximately at 4--4 in FIG. 3.

FIG. 5 is a diagrammatic plan view showing a modified form of the invention.

FIG. 6 is an elevation view, partly in section, of a modified form of proportioning pump.

The variable two-component pump is indicated in general by numeral 10 and is illustrated in FIG. 1 to be typically used to supply the pumpage to a mixer 11 from which the mixed components are conveyed by a long hose 12 to an airless sprayer 13. It should be recognized that supplemental equipment may be employed between the pump 10 and the mixer 11, for accomplishing such functions as heating and filtering the pumpage. In one typical usage, resin is supplied from one source 14, and catalyst is supplied from another source tank 15.

A motor 16 provides a rotary source of power for the pump 10 and is connected through a variable speed pulley 17, belt 18, and pulley 19 to the input shaft 20 of the pump. In the form of pump illustrated in FIGS. 2 and 3, the pump 10 has a housing 21 which defines a central chamber 22 defining a reservoir for hydraulic fluid. The shaft 20 is mounted on bearings 23 and 24, and defines an eccentric 25 which includes an eccentric portion 26 of the shaft 20 which is embraced by a ball bearing 27, the outer annular peripheral surface 27a of which gyrates as an eccentric around the rotation axis of the shaft 20.

The pump 10 includes a pair of diaphragm pumps 28 and 29, and a pair of piston pumps 40 and 41.

The two diaphragm puing the inlet side of the housing; a deflector deflecting the fluid to flow from the fluid inlet, through the filter body, and then out through the fluid outlet; a cleaning body having an inlet adjacent to the filter body and an outlet connectable to the atmosphere for effecting a self-flushing action of the filter body via the inlet of the cleaning body; drive means for moving said cleaning body with respect to said filter body to cause the cleaning body inlet to sweep along the cylindrical surface of the filter body facing the inlet side of the housing; and pressure-sensing means disposed within said deflector for sensing the pressure difference at the inlet and outlet sides of the housing and effective, upon sensing a predetermined difference, to actuate said drive means..]. 33. A self-cleanable filter, comprising: a housing having a fluid inlet, and a fluid outlet, a filter body within the housing and having a cylindrical surface facing the inlet side of the housing; and a cleaning body within the housing and movable axially from a home position along said cylindrical surface of the filter body for cleaning same; said cleaning body comprising a first section defining an internal chamber having a circular inlet opening facing the surface of the filter body to be cleaned and movable axially along said surface for cleaning same; and a second section having an outlet opening communicating with said internal chamber and located within said housing in the home position of the cleaning body but movable, upon the axial movement of the cleaning body, to connect said internal chamber to the atmosphere for cleaning the filter body by producing a reverse flow of fluid therethrough to the atmosphere, said second section of the cleaning body including a plurality of hollow rods disposed in a circular array with respect to said cylindrical surface of the filter body, one of the ends of the rods communicating with the internal chamber of said first section, the opposite ends of the rods projecting through the housing and being connected together by a circular member externally of the housing, said opposite ends of the rods being formed with outlet openings which are normally disposed within the housing but are movable externally thereof upon the axial movement of the cleaning body.