Multiple-dose, flush-through injector

Details Multiple-dose, flush-through injector Multiple-dose, flush-through injector

1999-05-21

2001-03-06

Doerrler, William (Department: 3744)

Refrigeration

With means for charging closed refrigeration producing system

C222S135000, C222S145500

Reexamination Certificate

active

06196016

ABSTRACT:

FIELD OF THE INVENTION
The field of the invention is refrigeration systems and refrigeration system servicing.
BACKGROUND OF THE INVENTION
Refrigeration systems, including mobile units and stationary units, require servicing from time to time. Refrigeration system servicing often involves the introduction of a fluorescent, leak detection dye into the system. Servicing similarly can involve the introduction of a liquid compressor lubricant, e.g., a mineral oil, a polyol ester, or a polyalkylene glycol. These liquids are introduced into refrigerant systems by means of devices commonly called “dye injectors” (or “oil injectors”). Although various dye injectors have been used, they can be generally classified into two types, i.e., flush-through-type and injection-type.
The feature that distinguishes conventional flush-through injectors is that refrigerant flow supplies the force that moves (flushes) the liquid dye from the injector into the refrigeration system. Conventional flush-through injectors are single-application devices. This means that the injector must be opened and refilled with dye, for each dose of dye injected. An additional limitation is that the dose per injection is fixed at the capacity of the dye chamber, which must be filled completely, to avoid introducing air into the refrigeration system.
The feature that distinguishes conventional injector-type devices is that the concentrated liquid dye is displaced from the injector by a mechanical pushing mechanism, instead of refrigerant flow. In other words, the fluid does not flow through the injector. This type of design is analogous to a caulking gun or a drug syringe. Conventional injectors allows multiple injections. However, unless the injector output hose remains filled with dye, it must be purged of air each time the injector is connected to a refrigeration system. With this type of device, a small amount of dye often remains at the point of attachment between the injector and the refrigeration system.
SUMMARY OF THE INVENTION
In general, the invention provides devices and methods for multiple-dose, injection of a liquid or paste into a closed system, using fluid flow through the closed system to move the liquid into the system. Thus, the invention achieves the advantages of a flush-through injector with the advantages of an injection-type injector, while avoiding their respective limitations.
The invention features a device for introducing a liquid or paste into a closed, fluid system. The device includes a fluid flow path between a fluid input port and a fluid output port; a liquid reservoir; a one-way reservoir output valve between the liquid reservoir and the fluid flow path, which valve is biased toward closure of a liquid reservoir outlet; and a liquid-expelling mechanism, whereby liquid or paste can be expelled from the liquid reservoir, through the one-way reservoir output valve, into the fluid flow path.
In some embodiments, the liquid reservoir includes a cylinder wall, and the liquid-expelling mechanism includes a piston. Some embodiments of the invention include a liquid flow path between the one-way reservoir output valve and the fluid flow path. The device can include a batch chamber in fluid communication with the fluid output port, and a one-way fluid input valve biased toward closure of the fluid input port. Typically, the ratio of liquid reservoir volume to batch chamber volume is at least 2:1, e.g., 10:1, 50:1 or 100:1. The batch chamber wall can be substantially transparent, thereby permiting visual confirmation of batch chamber filling and emptying. The device can include a shutoff valve (or service coupling) at the end of an output hose. This allows the device to be connected successively to different refrigeration systems without re-purging, once air is initially purged from the device. The device can include a mechanism for controllably moving the piston. The mechanism can be a threaded push rod and an actuation knob. For convenience in dispensing measured amounts of liquid, the actuation knob can be calibrated in relation to liquid reservoir volume, e.g., one batch chamber volume per knob rotation.
Some embodiments include a one-way valve biased in the closed position, at a reservoir fill port. Such an embodiment can include a push rod, with a handle and a handle pivot bar, for controllably moving the piston. The liquid reservoir input fitting can be compatible with an output fitting on a liquid source such as a detachable dye cartridge. In such an embodiment, the ratio of reservoir volume to batch chamber volume can be about 1:1, while the ratio of cartridge volume to reservoir volume is at least 2:1, and preferable at least 10:1.
Some embodiments of the invention are dual injectors, which include a second liquid reservoir, one-way valve, and liquid expelling mechanism associated with a single fluid flow path. Such embodiments provide for convenient injection of two different liquids, e.g., fluorescent leak detection dye and compressor lubricant, into a refrigeration system, using a single injector. Alternatively, both liquid reservoirs of a dual injector can be filled with the same liquid, thereby doubling the capacity for a single liquid.
The invention provides a refrigeration system service apparatus. The service apparatus includes a refrigerant reservoir, e.g., a conventional refrigerant cylinder, and an injector device as described above. The injector device can remain mounted on the refrigerant reservoir while the service apparatus is connected, disconnected, and reconnected to successively-serviced refrigeration systems. The refrigerant can be dispensed from the service apparatus with the injector remaining passive unless and until actuated.
The invention features a method for introducing a liquid or paste into a closed system. The method includes: (a) providing a fluid flow path that includes a one-way fluid input valve and a fluid output port; (b) providing a liquid reservoir; (c) providing a one-way reservoir output valve that permits liquid or paste to flow from the liquid reservoir into the fluid flow path at a point between the fluid input valve and the fluid output port; (d) connecting the fluid flow path into the closed system; and (e) forcing liquid or paste from the liquid reservoir, through the one-way reservoir output valve, into the fluid flow path, at a point between the fluid input valve and the fluid output port.
Examples of closed systems on which the method can be used include refrigeration systems, e.g., mobil air conditioners and stationary refrigeration systems. The method is useful for injecting a fluorescent leak detection dye, compressor lubricant, or other liquid, into a refrigeration system.
As used herein, “liquid reservoir” means an enclosure from which a liquid or paste is expelled through a one-way reservoir output valve, into a fluid flow path.
As used herein, “fluid” means a gas or a liquid.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present application, including definitions will control. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference.
Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described below. The materials, methods, and examples are illustrative only and not intended to be limiting. Other features and advantages of the invention will be apparent from the detailed description, and from the claims.


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