Patent Application
20090108103
This invention pertains generally to a liquid spray system and more particularly to a valve assembly of the spray system for liquid output control.
Spray systems with a spray nozzle assembly and a conventional valve assembly controlling a liquid flow rate are generally known in the prior art. The present assignee's product brochure as disclosed in the information disclosure statement describes such liquid spray systems. For example, the MeterMist model discloses a liquid spray system with a spray nozzle assembly attached to a metering body assembly including a piston pump and a valve assembly controlling liquid output. Such liquid spray system is used to apply coolant in applications like drilling, milling, tapping, stamping, or punch, or to apply lubricant in chainline or assembly applications.
In liquid spray applications, ability to maintain and control a liquid flow rate is desirable in achieving an optimal liquid coverage efficiency. The present invention relates to a liquid spray system with an improved valve assembly enhancing controllability of liquid output for applications that may have varying liquid flow rates and/or that may use different viscosity liquids.
The present invention provides for a spray system with an improved needle valve assembly having a variable orifice and a fixed orifice for enhanced controllability of liquid output. The liquid output control is enhanced when a variable orifice is adjusted to regulate a liquid flow rate while a minimum flow rate is precisely maintained by a proper selection of a fixed orifice.
According to one preferred embodiment, a spray system for various liquid applications includes a metering body connected to a liquid tank, a spray nozzle assembly, and a pressurized gas supply. In such system, a flow rate of liquid entering the metering body from the liquid tank is controlled by a valve assembly including a variable orifice and a fixed orifice. In an open variable orifice position, the liquid flow rate is controlled by a flow area of the variable orifice adjustable by a slidable needle valve, while a minimum liquid flow rate is maintained by a fixed orifice within the needle valve. In a closed variable orifice position, the liquid flow rate is controlled only by the size of the fixed orifice. The liquid regulated by the valve assembly is then transported into the spray nozzle assembly where the liquid is atomized by a gas stream from the pressurized gas supply forming a liquid spray.
According to one embodiment of a needle valve assembly, the needle valve has a conical valve control surface and sits in a valve body which includes an inlet and an outlet and a fluid passageway extending therebetween. The needle valve is slidable in a valve chamber toward and away from an annular valve seat arranged about the valve axis wherein a variable orifice is formed between the conical control surface and the valve seat. The needle valve also includes a fixed orifice maintaining a minimum flow rate and connecting the inlet and the outlet of the valve body in a parallel fluid circuit with the variable orifice.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
As shown in
The first gas supply 18 is directed through the spray nozzle assembly 16 where it atomizes a liquid such as lubricant to form a liquid spray. The second gas supply 20 in this embodiment is connected to the metering body 14 to drive a piston pump cycle, pumping a liquid from the liquid tank 12 through the metering body 14 into the spray nozzle assembly 16 where the liquid is atomized by the gas stream from the first gas supply 18, forming the liquid spray. The liquid tank 12 is connected to the metering body 14 and can either be gravity fed or with light pressure when desirable.
Referring to
As illustrated in
Considering the needle valve assembly 30 in more detail, with reference to
Referring to
The needle valve insert 68 is generally conical in shape and has a cylindrical shape portion 82 and a truncated tip 80. The fixed orifice 60 is formed through the needle valve insert 68 coaxially with the valve axis 49 and includes a restricted flow area 100 with a reduced diameter and a portion of the flow passageway with a larger diameter 102. The needle valve insert 68 has a cylindrical portion of its body 82 which has a cylindrical bore extending through the cylindrical portion of its body, defining a compartment 84 in which the valve stem 70 is mounted. The valve insert 68 also has a portion of its body defining a conical control surface 54 which includes a stepped axial bore defining the fixed orifice 60. The axial bore has coaxial bore portions defining a restricted flow area 100 and an increased diameter fluid passageway 102 within the valve insert 68. The transition between bore portions 100 and 102 is tapered. The restricted flow area 100 extends to the truncated tip 80 defining a fixed orifice inlet 62. The fixed orifice inlet 62 opens to the fluid passageway 46 which is connected to the piston chamber 34.
The needle valve stem 70 is mounted in the valve insert compartment 84 completing the fixed orifice fluid circuit 60. The valve stem 70 is a solid, one-piece element which includes a cylindrical main body portion 86, a reduced diameter cylindrical portion 88, and a head portion 90 which includes axial and radial fixed orifice passageways 104, 106. The needle valve stem 70 includes an axial bore 104 with a diameter equivalent to the diameter of the valve insert passageway 102. The axial bore 104 extending from the end of head portion 90 continues through until it meets a radial bore 106. The axial passageway 104 is orthogonally connected to the radial flow passageway 106. The radial bore 106 extends through one side of the head portion 90 defining a fixed orifice outlet 64. The head portion 90 fits into the valve insert compartment 84, connecting fluid passageway 102 of the valve insert 68 with the axial passageway of the valve stem 104, thereby defining the fixed orifice 60 extending from the fixed orifice inlet 62 to the fixed orifice outlet 64. The fixed orifice outlet 64 opens to the fluid passageway 46 leading to the nozzle assembly.
The reduced diameter cylindrical portion 88 of the valve stem 70 is connected to the cap dial 78. The cap dial 78 has a cylindrical bore 79 through its body where the reduced diameter 88 of the cylindrical valve stem 70 is tightly fitted. The main body portion 86 of the valve stem 70 has threads on its outer surface. The adapter 76 is generally cylindrical shape and has a larger diameter portion with hexagonal outer surface and a reduced diameter portion. The adapter 76 is bored through with complementary threads on its inner surface which mate the threads on the valve stem, thereby enabling manual adjustment of the needle valve stem 70 together with the needle valve insert 68 by rotating the cap dial 78. For example, in one preferred embodiment of the needle valve assembly 30, turning the cap dial 78 in a clockwise direction moves the needle valve 48 toward the valve seat 52, decreasing the variable orifice gap 56, and ultimately engages the conical control surface 54 with the valve seat 52 to a closed variable orifice position. In such operation, a liquid flow rate is reduced as the variable orifice decreases until the liquid flow through the variable orifice 56 is stopped in the closed variable orifice position, while a minimum liquid flow rate is maintained by the fixed orifice 60.
The minimum flow rate of liquid in the present invention is controlled by a fixed orifice flow area 60. The controllability of the minimum flow rate is enhanced with the metering body 14 which includes multiple interchangeable needle valve assemblies 30, each with a fixed orifice of a different flow area to provide for different minimum liquid outputs. By a way of selecting a proper valve assembly 30 according to the viscosity of a liquid, a desired minimum flow rate may be obtained. Efficiency of an operation is improved when a quick changeover to a different liquid is made possible with multiple interchangeable valve assemblies 30. Alternatively, the metering body 14 may include a kit having multiple interchangeable needle valve inserts 68, each with a fixed orifice of a different flow area to provide for different minimum liquid output.
Referring back to
Once the regulated amount of liquid passes the valve assembly 30, the liquid is transported through the liquid passageway 46 exiting out of the fluid outlet 42 of the metering body 14 and enters a fluid passageway 26 of the spray nozzle assembly 16. A gas stream from the first pressurized gas supply 18 flows into the spray nozzle assembly 16 and passes through a gas passageway 22, expelling at the nozzle tip 28. The exiting gas stream creates a venturi effect placing a suction on the fluid passageway 26 at the tip of the nozzle 28, thereby expelling the liquid into the gas stream where the gas stream atomizes the liquid, forming a liquid spray output.
In a normal operation of this embodiment, the liquid enters the metering body 14, continuously in a low volume, and is controlled by a needle valve assembly 30 with a variable orifice 56 and a fixed orifice 60. In low liquid volume applications using low viscosity liquids, the variable orifice 56 remains closed, leaving only the fixed orifice 60 for the liquid output control. For applications with higher viscosity liquids or higher liquid volumes, the variable orifice 56 is opened to obtain a desired liquid flow rate.
The needle valve assembly 30 in the alternative embodiment is same as the needle valve assembly 30 described above in the first preferred embodiment. In this spray system 10, the needle valve assembly 30 is selected according to the liquid viscosity in a particular application. For example, a needle valve assembly 30 with a smaller fixed orifice flow area is selected for lighter liquids with a low viscosity or where a low liquid flow rate is desired. In such applications, the variable orifice 56 remains in the closed position to stop liquid flowing through the variable orifice 56. For applications involving heavier liquids with a higher viscosity, the variable orifice 56 is adjusted manually with the cap dial 78 until a desired liquid flow rate is obtained. Thus, controllability of liquids with different viscosities is improved through use of both the variable orifice 56 and the fixed orifice 60.
Moreover, the improved needle valve assembly allows for expanded utilization of a spray system by enabling applications of liquids with different viscosities simply by exchanging the needle valve assembly 30 and adjusting the variable orifice 56. This embodiment of the spray system 10 may be used for paint spray applications, lubricant applications for stamping, punch, assembly operations, and chainline lubrication. The spray system may also be used for some food applications such as coating baking trays.
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
