Patent Application
20060228621
The invention relates to quick connect couplings adapted for use with electric battery water replenishment systems.
Electrical batteries that have aqueous electrolytes and see heavy duty industrial use, such as large industrial lead-acid batteries powering fork-lift trucks, consume water during recharging. Water in the electrolyte breaks down into oxygen and hydrogen gases as a result of electrolysis during charging. The gases bubble up through the electrolyte and escape from the battery housing through a vent opening. The electrolysis causes a loss of water from the electrolyte solution, and as a result, such batteries require periodic replenishment of the lost water.
For large batteries with many cells, single point watering systems were developed to avoid the error-prone, labor-intensive and tedious process of visually inspecting and manually watering each cell individually. Single point watering systems may comprise, for example, float valves positioned in each cell, the cells being linked together by a system of water supply conduits which feeds water to the cells through the float valves. When water replenishment is required, the water supply conduit system is connected to a water reservoir, water flows from the reservoir to the cells and the float valves close to cut off the flow of water once their respective cells are filled.
For batteries having many cells, it is tedious and expensive to construct a water supply conduit system. The large number of battery cells result in large numbers of valves, each of which may be connected to two sections of conduit. Thus, each cell may require two connectors, and additional connectors will also be necessary to complete the system. The most common tubing connection method uses flexible tubing and fittings having barbed ends. The fittings may be part of a valve, or may stand alone as required to effect the necessary connections. In constructing such a system, the end of a flexible tube is pushed directly on to a barbed fitting. Sometimes, a clamping ring is added to hold the tube in place against high water pressure. While this method is inexpensive and operates satisfactorily in most applications, it is both laborious and time-consuming to install on the battery. For example, typically an installer will use a heating system such as an oven, hot air gun or hot water to soften the tubing before pushing it on to the barbed fitting. The tubing shrinks as it cools to make a tight connection. However, if a moderately high pressure is to be used, say 30 psi or more, the installer will use the additional ring clamps to prevent the tubing from blowing off the barbed fitting. Since there may be well over 80 connections of this type to make on a single 40 cell battery, it is clear that a better and quicker attachment means would be preferred by users.
There is a type of quick connect coupling that has found use in household plumbing systems as well as hydraulic oil systems for industry. Such quick connect couplings allow a conduit to be inserted into the coupling where it is held fast in a fluid tight connection using a seal such as an O-ring and a retainer positioned within the coupling. The retainer has a set of metal teeth that are forced into engagement with the conduit. The teeth cut into the tubing, which is usually plastic, and hold it firmly in sealing relation with the coupling. Internal pressure or external forces that would tend to withdraw the conduit from the coupling are resisted by the teeth, which are integrated in any one of a number of self-jamming arrangements that cause them to engage the conduit with a force proportional to the applied force tending to withdraw the conduit from the coupling.
Quick connect couplings as described above have thus far never been used in battery water replenishment systems. Such couplings are generally used in applications with high fluid pressures, for example 100 psi, and are generally recommended by their manufacturers to be used in conjunction with rigid or semi-rigid tubing only, such as polyethylene, polypropylene, polybutylene, rigid PVC or even metal pipe because the softer tubing, such as flexible PVC or rubber, tends to pull out easily and thereby fails to form a fluid tight connection. In fact, these push in couplings are generally considered to be incompatible with soft flexible tubing. In cases where soft tubing must be used, it is generally recommended that ferrules made from rigid materials be placed inside the ends of soft tubing to reinforce those ends, before pushing the tubing into the coupling. This gives the tubing enhanced rigidity, making the soft tubing into rigid tubing at its ends.
Additional disadvantages are inherent in these prior art retainers which find their source in the use of metal teeth. It is preferred to avoid any use of metal in battery watering systems due to the corrosive effects of the electrolyte, typically sulfuric acid, which attacks most metals including some stainless steels. It is especially undesirable to have metal form internal components that are critical to the proper functioning of a device such as the retaining teeth of a coupling. However, common wisdom dictates that metal must be used for retainers so that they hold an edge and have sufficient strength to cut into and hold the conduit as required.
Another disadvantage of using metal in internal components such as retainers is the cost. Metal retainers or retainers made of a combination of plastic and metal cost as much as 10-15 times greater than an all plastic retainer.
Combination metal and plastic retainers further suffer from a higher part count than retainers made of a single material that can be made in a unitary fashion, for example, molded from plastic resin.
It is clear that there is a need for a quick connect coupling that is useable with soft tubing in an acid environment and that does not suffer the disadvantages corrosion, excessive cost and high part count of prior art couplings.
The invention concerns a quick connect coupling for use with plastic conduit in an acid environment, for example, in a battery water replenishment system. The coupling comprises a housing having an inlet for receiving the conduit and an outlet. A collar is positioned within the inlet. The collar has a tapered bore with a smaller diameter facing the inlet. A retainer member is disposed within the collar so as to be movable axially relative to the collar. The retainer member has a plurality of flexible fingers connected to one another at a proximal end. The fingers extend longitudinally therefrom to a distal end and are positioned relative to one another so as to receive the conduit between the fingers. Each of the fingers has a tooth positioned distally from the proximal end. Each tooth projects inwardly so as to engage the conduit inserted within the inlet. Each tooth grips the conduit and is urged thereagainst by the tapered bore of the collar upon axial motion of the conduit and the retainer member in a direction outward from the housing.
Preferably each tooth is formed of plastic and extends transversely to the conduit. The retainer member may comprise a collet having a ring member from which the fingers extend. The conduit is received through the ring member. Preferably the collet is formed as a unitary member from a plastic resin.
In operation, the teeth of the retainer member are urged against the conduit by contact between the fingers and the tapered bore. The collar may be formed as either an integral or a separate member from the housing.
The invention also includes valves adapted for use with battery watering systems, as well as batteries having watering systems that use a quick connect coupling as described above.
Valve 12 has a quick connect coupling 26 which has an inlet 32 that receives conduit 20, a first outlet 34 (see
Coupling 24 comprises a housing 38 that defines the inlet 32. A collar 40 is positioned within the inlet 32. The collar may be a separate member as shown in
A retainer member 48 is disposed within the collar 40. The retainer member comprises a plurality of flexible fingers 50 connected to one another at a proximal end 52. Preferably the fingers 50 are connected to one another by being attached to a ring 54, the ring 54 and fingers 50 forming a collet 56 that is axially moveable relatively to the collar 40. An axis 55 extending longitudinally and defining the axial direction of motion of the collet is shown for orientation purposes. As shown in
Preferably, the conduit 20 is formed from a soft, acid resistant plastic tubing, such as polyethylene. The housing, collar and collet, including the fingers 50 and the teeth 58 are also formed from acid resistant plastic, particularly plastics that are resistant to sulfuric acid. Such plastics include polyethylene, polypropylene, polycarbonate or ABS plastic by way of example. By making the retainer member entirely from acid resistant plastic and avoiding the use of metal, several advantages are realized. First, the problem of corrosion that is associated with metal teeth is avoided. The acid environment of the battery causes accelerated corrosion of metal parts and will thus cause couplings having metal components to fail rapidly, requiring frequent replacement. Second, the cost of the all plastic collet is significantly less than one which includes metal teeth integrally molded within the fingers. Finally, the all plastic collet has a lower part count, thereby achieving simplicity of design. It is thought throughout the industry that metal teeth are necessary to ensure a reliable connection between the coupling and the conduit, and that plastic teeth will not be adequate. However, tests have shown that for self watering battery systems as described herein, a plastic collet having plastic teeth performs adequately and provides a reliable, fluid-tight joint.
The operation of the quick connect coupling according to the invention is described with reference to
The embodiments thus described are preferred for conduit having a diameter up to about 12 mm. For larger diameter conduit it may be desirable to reinforce the conduit with a ferrule 70 as shown in
Couplings according to the invention may be used as stand alone devices or with valves to provide a single point watering system for lead-acid batteries that does not suffer from the problems of corrosion, excessive cost and high part count, and provide a system that is easy to install rapidly to provide reliable, fluid tight joints.
This application claims priority to U.S. Provisional Application No. 60/662,498, filed Mar. 16, 2005, which is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60662498 | Mar 2005 | US |
