Liquid delivery system

This application claims benefit, under 35 U.S.C. §119(e), of U.S. Provisional Application Ser. No. 61/672,465 filed on Jul. 17, 2012, and U.S. Utility application Ser. No. 13/681,601 filed Nov. 20, 2012, the contents and substance of which are herein incorporated by reference.

1. Field of the Invention

This invention relates generally to liquid delivery systems, and is concerned in particular with the on demand mixture and constant flow delivery of multiple liquids, some of which may have elevated viscosities and/or levels of suspended solids, and others of which may require delivery at extremely high ratios.

2. Description of Related Art

As herein employed, the term “on demand” means a system in which the mixture of liquid components occurs in response to and simultaneously with delivery of the resulting mixture.

With reference to FIG. 1 , a prior on demand liquid mixing and delivery system is generally depicted at 10 and includes a mixing chamber 12 . A first liquid component, which may for example be water received via a conduit 13 from a municipal water source, is supplied to the mixing chamber via a first supply line 14 . The first supply line includes a first constant flow valve 16 , a downstream metering orifice 18 and an optional check valve 20 .

As herein employed, the term “constant flow valve” means a flow control valve of the type described, for example, in any one of U.S. Pat. Nos. 7,617,839; 6,026,850 or 6,209,578, the descriptions of which are herein incorporated by reference in their entirety.

These types of valves are normally closed, are opened in response to pressures exceeding a lower threshold level, are operative at pressures between the lower threshold level and an upper threshold level to deliver liquids at a substantially constant pressures, and are again closed at pressures above the upper threshold level.

A second liquid component, e.g., a tea concentrate, is received via conduit 22 and is supplied to the mixing chamber 12 via a second supply line 24 . Conduit 22 is connected to a pressurized source of the second liquid component, one non limiting example being a pump 26 , which may be driven by compressed air received via conduit 27 . The second supply line includes a second constant flow valve 28 , a downstream second metering orifice 30 having a fixed size, and another optional check valve 32 . The first and second constant flow valves 16 , 28 serve to deliver the first and second liquid components to the mixing chamber 12 at substantially constant pressures, irrespective of variations in the input pressures in the conduits 13 , 22 between the upper and lower threshold levels of the valves, and at substantially constant flow rates governed by the flow resistances of the first and second metering orifices 18 , 30 .

The first and second liquid components are combined in the mixing chamber to produce a liquid mixture having a mix ratio governed by the selected variable size of the first metering orifice 18 and the fixed size of the second metering orifice 30 .

Although not shown, it will be understood that the locations of the first and second metering orifices 18 , 30 may be reversed, with the adjustable metering orifice 18 being located in the second supply line 24 and the fixed metering 30 orifice being located in the first supply line 14 . Alternatively, the first and second supply lines 14 , 24 may both be equipped with either fixed or adjustable orifices.

A discharge line 34 leads from the mixing chamber 12 and through which the liquid mixture is delivered to an on/off dispenser 36 . A third metering orifice 38 is provided in the discharge line 34 . As shown, the third metering orifice is upstream and separate from the dispenser 36 . Alternatively, the third metering orifice may be included as an integral component of the dispenser.

When the dispenser is open, the discharge line 34 has a maximum flow rate that is lower than the combined minimum flow rates of the first and second supply lines 14 , 24 , thus creating back pressures in the first and second supply lines downstream of their respective constant flow valves 16 , 28 . These back pressures, together with the inlet pressures applied to the constant flow valves, maintain the constant flow valves open, thereby delivering the first and second liquid components to the mixing chamber at substantially constant pressures and flow rates.

For many applications, the above described system operates in a generally satisfactory manner, although there are certain applications that can be potentially problematic. For example, when the second liquid component has an elevated viscosity and/or level of suspended solids, and the ratio of the first liquid to the second liquid is relatively high, e.g., 400:1 there is a danger that the metering orifice 30 in the second supply line 24 will become plugged, necessitating a shut down of the system while the metering orifice is either cleaned or replaced. Such maintenance procedures are both disruptive and costly.

Even when the second liquid has a relatively low viscosity and has little if any suspended solids, its mixture with the first liquid at extremely high ratios on the order of 1000:1 can be difficult if not impossible to achieve due to limitations imposed by the metering orifices.

Also, for certain liquid combinations, adequate mixture in the mixing chamber 12 may be difficult to achieve, resulting in a less than a homogeneous mixture being delivered to the dispensing valve.

Broadly stated, the objective of the present invention is to provide an improved on demand liquid mixing and delivery system which addresses each of the above described shortcomings of the prior liquid delivery system.

In accordance with one aspect of the present invention, an on demand liquid mixing and delivery system comprises a manifold defining a mixing chamber. The manifold has first and second inlets communicating with the mixing chamber, and an outlet connected to an on/off dispenser. A first constant flow valve has a first outlet connected to the first manifold inlet via a first supply line. The first constant flow valve is adapted to deliver a first liquid to the mixing chamber at a substantially constant first pressure. A second constant flow valve has a second outlet connected to the second manifold inlet via a second supply line. The size of the second manifold inlet is at least as large as the size of the second outlet. The second constant flow valve is adapted to deliver a second liquid to the mixing chamber at a substantially constant second pressure greater than the first pressure.

The second supply conduit lacks any metering orifice. Instead, flow resistance in the second conduit is provided primarily by the length and/or internal size of at least a section of the second conduit, with that section advantageously being readily interchangeable with other sections having different lengths and/or internal sizes selected to provide flow resistances suitable for fluids having different viscosities and/or levels of suspended solids.

According to another aspect of the present invention, extremely high ratios can be achieved by atomizing one or more of the liquid components of the liquid mixture being delivered to the dispenser.

According to still another aspect of the present invention, mixture of the liquid components may be enhanced by the introduction of pressurized air into the mixing chamber.

These and other objectives, features and advantages of the present invention will now be described in greater detail with reference to the accompanying drawings, wherein:

FIG. 1 is a diagrammatic illustration of a prior liquid delivery system;

FIG. 2 is a diagrammatic illustration of a liquid delivery system in accordance with an exemplary embodiment of the present invention; and

FIG. 3 is a diagrammatic illustration of an alternative manner of incorporating atomized liquid into the liquid mixture being delivered to the dispenser.

An exemplary embodiment of an on demand liquid mixing and delivery system embodying aspects of the present invention is depicted at 40 in FIG. 2 . The same reference numbers have been employed to designate components of the system 40 that are similar or identical to those of the prior system 10 illustrated in FIG. 1 .

The mixing chamber 12 has first and second inlets 12 a , 12 b and an outlet 12 c . The first constant flow valve 16 has a first outlet 16 a connected by supply line 14 to the first inlet 12 a . The first constant flow valve 16 is adapted to deliver a first liquid to the mixing chamber 12 at a first pressure.

Similarly, the second constant flow valve 28 has a second outlet 28 a connected by supply line 24 to the second inlet 12 b . The second constant flow valve 28 is adapted to deliver a second liquid to the mixing chamber at a second pressure that is greater than the first delivery pressure of the first constant flow valve. The size of the second inlet 12 b is at least as large as the second constant flow valve outlet 28 a.

According to one aspect of the present invention, the second supply line 24 lacks any metering orifice. Instead, flow resistance to the second liquid being delivered to the mixing chamber is provided exclusively by the second supply line, and primarily by the length and/or internal size of at least one conduit section 42 of the second supply line. Advantageously, quick disconnect couplings 44 allow the conduit section 42 to be readily interchanged with other conduit sections having different lengths and/or internal sizes selected to provide different flow resistances suitable for liquids having different viscosities and/or levels of suspended solids. In comparison to conventional orifices, the conduit sections 42 are far less prone to plugging, and thus contribute advantageously to trouble free operation of the liquid delivery system.

According to another aspect of the present invention, an atomized third liquid is incorporated into the liquid mixture being delivered to the dispenser 36 . Atomization may be achieved by compressed air received via conduit 46 and fed through a third constant flow valve 48 connected to the mixing chamber 12 by a third supply line 50 .

The third supply line includes a check valve 52 and an atomizer 54 , one non-limiting example being a Micro Mist Nebulizer available online at justnebulizers.com. The third liquid is drawn by the atomizer 54 from a container 56 and directed through a third metering orifice 58 and into mixing chamber 12 where it is combined with the first and second liquids.

Alternatively, as depicted in FIG. 3 , the third supply line 50 may bypass the mixing chamber 12 and may be connected to the discharge line 34 .

According to still another aspect of the present invention, in order to enhance the mixture of liquids in the mixing chamber 12 , compressed air received via conduit 60 and a fourth constant flow valve 62 may be introduced into the mixing chamber 12 via a fourth supply line 64 including a check valve 66 and a fourth metering orifice 68 .

A typical non-limiting example of the use to which the above described system may be put is the on demand dispensing of tea at rates of between 1.0 and 2.0 oz/sec., where the mixture being fed to the on/off dispenser 36 includes water delivered to the mixing chamber 12 via supply line 14 , a tea concentrate delivered via supply line 24 , and an essense to enhance the tea aroma of the dispensed mixture delivered via supply line 50 .

When dispensing the tea mixture at a rate of about 1.5 oz/sec., exemplary ratios of water to tea concentrate may range between 11/1 and 5/1, with the essence contributing about 0.001% of the mixture being provided to the dispenser. If enhanced mixing is required, compressed air at about 14.5 p.s.i may be introduced into the mixing chamber 12 .

When the dispenser 36 is closed, back pressures in the supply lines 14 , 24 , 50 and 64 increase and contribute to a rise in the operating pressures of the constant flow valves 16 , 28 , 48 and 62 above their respective upper threshold levels, causing the valves to close. When the dispenser is opened, back pressures drop to levels permitting the constant flow valves to open and operate between their respective upper and lower threshold levels.