TECHNICAL FIELD

The invention relates to devices for injecting liquid into pressurized systems. More particularly, it relates to such devices for injecting liquids into air conditioning systems.

BACKGROUND ART

Air conditioning systems often leak refrigerant This is undesirable from an economic point of view as the system will not operate as efficiently with reduced quantities of refrigerant, and the refrigerant needs to be replaced. It is also undesirable environmentally.

Leak detection is generally performed by injecting a fluorescent dye into the system. Typically dyes used for this purpose fluoresce in the ultraviolet region, so an ultraviolet light is shone on the system. Wherever leaks occur the dye will escape the system and fluoresce under the light.

A number of injectors have been developed for getting liquids into an air conditioning system. US patent number 4,745,772 issued May 24, 1988 to Ferris describes a chemical additive device. The device has a container that unscrews to allow access to the interior for pouring in the additive. The container is screwed back together, the device is connected to the air conditioning system and the additive is injected under pressure into the system. Although there is no indication in the Ferris patent of the material used for the container, it is likely to be metal or some other visually solid material capable of withstanding the pressures used in air conditioning systems.

US patent number 4,938,063 issued July 3, 1990 to Leighley discloses a mist infuser for infusing a fluorescent dye into an air conditioning system. The Leighley infuser has two concentric glass cylinders sandwiched between two circular end caps. Together the end caps and the small cylinder define a reservoir. One end cap has a circular inlet through its centre, while the other has an outlet. An inlet bore opens from the outlet, perpendicular to it, through the circumference of the outlet end cap. Similarly, an outlet bore opens to the inlet from the circumference of the inlet end cap. The bores have respective sealing caps.

In operation, the infuser is turned on its side and the sealing caps are removed. The dye is added through the inlet bore, while air escapes through the outlet bore. The level of the dye is visible through the glass cylinders.

The Leighley device has a number of drawbacks. It is expensive to manufacture and assemble due to the number of components and their specialized nature. The device must be filled on its side which is very cumbersome. The glass is susceptible to being broken. This is the likely reason for having two glass cylinders, one inside the other, to contain the dye in the event of breakage. Even if the glass is not broken, it is susceptible to being scratched, possibly, impairing sight to the interior.

Another problem in the art is the desire for different sized injectors. Injectors can be used not only for the injection of dye, but also refrigerant oil and other liquids. Different jobs will require different amounts of liquid to be injected. Typically small amounts of

dye are injected, while larger amounts of oil are injected. However, the amounts used for each can vary from application to application. The use of many sizes of injectors is expensive. The use of an oversized injector is not always possible and, even if it is

possible, it is wasteful of dye or oil. Also, in the leak detection process there is typically a desirable ratio of dye to refrigerant. Adding more dye can decrease the effectiveness of the process and can contaminate the refrigerant in the system.

It is an object of the invention to address these or other problems with devices for the injection of liquids into pressurized systems.

DISCLOSURE OF THE INVENTION

In a first aspect the invention provides an injector for use in injecting a liquid into a pressurized system using a charging system. The injector has a generally tubular body having a generally tubular interior. A non-opaque tube is inserted into the interior of the body. The body receives fluid connections at opposing ends of the body to the charging system and to the pressurized system, respectively. At least one opening through the tubular body, not at the opposing ends, is used for viewing the liquid in the tube. The tube and body are in sealed connection such that the liquid will not escape through the at least one opening while under pressure. The tube and body receive the liquid prior to injection into the pressurized system.

The tube may be translucent or transparent, and it may be uncoloured. It may be a glass tube, possibly clear borosilicate glass.

A valve coupler at one of the opposing ends of the body may connect to an on-off valve between the coupler and die pressurized system. There may be an end fill cap at the other opposing end for connection to die charging system. The end fill cap may be manually releasable from the body to provide interior access to the injector for filling the tube with the liquid. The liquid may be poured into the injector through the interior access when the body is held sufficiently upright to retain the liquid.

The at least one opening may be at least two openings, one for viewing and the others for allowing light to pass into the tube.

The charging system may be a refrigerant charging system. The liquid may have a fluorescent dye component for leak detection. The pressurized system may be an air conditioning system.

In a second aspect the invention provides a liquid injection system made up of the pressurized system, charging system and injector of the first aspect

In a third aspect the invention provides a method for operating the injector of the first aspect by the following steps. First, connect the opposing ends of the body to the charging system and to the pressurized system, respectively, while fluid connection to the pressurized system is disabled. Fill the tube and body in a generally upright position with the liquid. Second, enable fluid connection to the pressurized system. Third, inject the liquid into the pressurized system using the charging system. Fourth, view the tube through the opening to determine if a sufficient amount of the liquid was propelled from the injector by the charging system.

In a fourth aspect the invention provides a supplemental reservoir for use with an inline end fill injector, such as the ones described above, having an end cap with a first thread for threading to a second thread of a first opening of the injector. The reservoir has a hollow receptacle enclosing a chamber. The receptacle has first and second aperaturcs to the chamber. The first aperature is surrrounded by a third thread corresponding to the second thread on the first opening of the body of the injector. The second aperature is surrounded by a fourth thread corresponding to the first thread on the end cap.

The chamber may be cylindrical. The receptacle may have a cylindrical adaptor with a first open end opposing a first enclosed end. The first enclosed end would have the first aperature. The receptacle may further have a cylindrical base with a second open end opposing a second enclosed end. The second enclosed end has the second aperature. The first and second open ends have corresponding threads.

In a fifth aspect the invention provides a reservoir set for use with an inline end fill injector such as those described above. The set has a plurality of supplemental reservoirs as described above. The set may have reservoirs with chambers of different capacities. The set may have a first reservoir with a chamber having a 2 ounce capacity, a second reservoir with a chamber having a 3 ounce capacity, and a third reservoir with a chamber having a 4 ounce capacity.

In a sixth aspect the invention provides an adaptor set for use with an inline end fill injector of the type described above. The adaptor set has a plurality of cylindrical adaptors of the type described above for the reservoirs. The adaptors may have different distances between the respective first enclosed ends and first open ends to provide for different capacities. The adaptor set may have three adaptors which when combined with the base will enclose chambers having capacities of 2 ounces, 3ounces and 4 ounces, respectively.

BRIEF DESCRD7TION OF THE DRAWINGS

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which show the preferred embodiment of the present invention and in which:

Figure 1 is a perspective exploded view of an injector according to the preferred embodiment of the present invention,

Figure 2 is a cross-section of the injector of Figure 1 ,

Figure 3 is a sketch of the injector of Figure 1 connected to a charging system and a pressurized system,

Figure 4 is an exploded perspective sketch of a supplemental reservoir according to the referred embodiment of the invention in combination with an inline end fill injector.

Figure 5 is a cross-section of the combination of Figure 4, and

Figure 6 is an exploded perspective sketch of an adaptor set employing the combination of Figure 4.

MODES FOR CARRYING OUT THE INVENTION

Referring to Figures 1 and 2, an injector 1 has a valve coupler 3, a valve coupler seal 5, a tube 7, a tube seal 9, a body 11, a fill cap seal 12, and a fill cap 13.

The coupler 3 has a conical nipple 15 with exterior thread 17, and a tubular plug section 19 with exterior threads 21. Through the centre of the coupler 3 is a bore 23.

The valve coupler seal 5 is a flat ring seal for durability, while the tube seal 9 and the fill cap seal 12 are O-ring seals. Neoprene O-rings are used as they tend to expand outwardly as they are compressed thus providing additional sealing surface, while they rebound to their original position when compressive forces are removed thus reducing the tendency to stick to the surfaces that are compressing them. As well, neoprene has

been found to be suitable for use with fluorescent dyes typical in automotive air conditioning applications. Those skilled in the art will recognize that other seals and sealing mechanisms may be used.

The tube 7 may be formed from any suitable material, such as borosilicate glass. The material should be chosen for specific clarity, strength and compatibility requirements of a given application. Although the tube 7 and the body 12 do not have to be tubular, this is certainly the easiest configuration for manufacturing purposes.

The fill cap 13 has a tubular plug 25 with exterior threads 27. The cap 13 has a grip section 29 with a roughened surface 31. Inside the grip section 29 about the centre of the cap 13 is a reverse conical thread 33 (see Figure 2) into the cap 13. The thread 33 corresponds to the thread 21. Through the centre of the cap 13 is a bore 35.

The body 11 is tubular and has threads 37, 39 at opposing ends about its interior. Between the threads 37, 39 through the body, equally spaced about die axis of the body 11, are three openings 41 (two openings 41 are evident in Figure 1, while only one is shown in Figure 2). Beyond the threads 37 moving into the body 11, the internal diameter of the body 11 is narrowed by an annular projection 43. Between the projection 43 and the threads 39, the internal diameter of the body 11 widens to a support surface 45.

The injector 1 is assembled by inserting seal 9 into the body 11 past the threads 39 until it meets the projection 43. The tube 7 is inserted in a similar manner. The external diameter of the tube 7 and the internal diameter of the support surface 45 are matched to allow for expansion and contraction differences between the various materials at the temperatures likely to be encountered by the injector 1. A few thousands of an inch

between the tube 7 and body 11 is usually sufficient at operating temperatures. The seal 5 is then inserted into the injector 1 and the coupler 3 threaded into the body 11. The coupler 3 squeezes the seals 5, 9 and creates a continuous surface from the projection 43 through the internal diameters of the seal 9, the tube 7, the seal 5 and the coupler 3.

5 To remove the tube 7, for cleaning, repair or replacement, the reverse process is followed.

The fill cap seal 12 is inserted to the opposite side of the projection 43 and die fill cap 13 is threaded into the body 11 until the fill cap 13 squeezes the seal 12 and creates a continuous surface from the projection 43 through the internal diameters of the seal 12 0 and the fill cap 13.

Referring to Figure 3, a charging system 49 has a high pressure side 51 and a low pressure side 53 and is connected to a source of refrigerant supply 55. A low side hose 57 is connected from the charging system 49 and threaded into the threads 33 of the cap 13. The valve coupler 3 is threaded at the threads 17 into an on-off two way ball valve 15 59. Another suitable valve could be used, however a two way is recommended in case the injector 1 is connected backwards. The valve 59 is connected through a further low side charging hose 61 to the low side 62 of an air conditioning system 63.

In operation, the valve 59 is closed, die fill cap 13 is manually unthreaded from d e body 11 at the threads 27 by gripping the roughened surface 31. The body 11 is held vertically 20 and liquid to be injected into the air conditioning system 63 is poured into the tube 7 up to the threads for the fill cap 13. The fill cap is then re-threaded into the body 11.

Excess liquid is squeezed out the threads 27 as the fill cap 13 is threaded. This ensures that a minimum of air is retained in the injector 1. Injecting air into an air conditioning system 63 could render d e system 63 unstable and potentially dangerous.

The valve 59 is dien opened to provide fluid connection to d e air conditioning system 63. The charging system 49 is activated using refrigerant to propel the liquid from the injector 1 into the system 63. Having the valve coupler 3 immediately adjacent d e valve 59 lessens the chance that air will be introduced between the injector 1 and the valve 59 and injected into the pressurized system.

Examples of liquids that can be used are a fluorescent dye, refrigerant oil combination used to detect leaks from the system 63 as the dye escapes from the system 63 and is made visible using an ultraviolet light. The dye has a distinctiy different colour from refrigerant. The interior of the injector 1 can be viewed through one opening 41 and d e tube 7, while light flows in the other openings 41 and die tube 7 to illuminate the interior. In this way one can check ύiat the dye has been fully propelled from die injector 1.

The tube 7 must at a minimum be non-opaque to allow the user to determine if sufficient amounts of the liquid have been propelled. Determining a sufficient amount will depend on the particular application of the user. For better viewing it is preferable to use a transparent tube 7. The colour of the tube 7 must be compatible with the contents to be viewed. For example, some fluorescent dyes are yellow and refrigerant is clear so die use of a yellow tube 7 is not advisable. For the widest general use, the tube 7 will be clear.

The body 11 shields the tube 7 as the injector 1 may be subject to a good deal of knocking about in a shop or repair environment. The body 11 can be machined from

aluminum or brass stock, witii the valve coupler 3 and fill cap 13 separately manufactured, preferably from the same material as the body for compatibility purposes. The body 11 can be formed from other materials of suitable strength that are compatible witii the liquid.

The preferred embodiment has been described witii reference to injection of dye into an air conditioning system 63. For use witii automotive air conditioning systems pressures are typically in the range of 145 to 180 psi. It will be evident to those skilled in die art that the principles described herein can be extended for use in other applications where liquids are to be injected under pressure. For example, d e injector could be used to inject refrigeration oil or to inject chemical additives as described in US patent no. 4,745,772 issued May 24, 1988 to Ferris mentioned previously.

In another aspect, Figures 4 and 5 show a supplemental reservoir 401 used in conjunction witii an inline end fill injector 403. The injector 403 could be the same as the injector 1; however, it does not need to be. The injector 403 need only separate between an end cap 429 and a body 407. Like names are used for components that are similar in the Figures showing injector 403 to those in the Figures showing the injector 1; a detailed description will not be repeated. Although the injector 403 is shown without a window, such as opening 41 of injector 1, a window would continue to be useful for die reasons discussed above with regard to die injector 1.

The reservoir 401 has a cylindrical adaptor 409 and a cylindrical base 411. The adaptor 409 is enclosed at one end, except for an aperature 413. The aperature 413 is surrounded by a cylindrical nipple 415 witii threads 416. The threads 416 correspond to direads 417 in a first opening at one end of the body 407. At die opposing end, die

adaptor 409 has outside threads 418. The base 411 has interior threads 419 at one end, corresponding to threads 418. The opposing end of die base 411 is enclosed, except for an aperature 421 surrounded by tiireads 423 (see Figure 5).

The adaptor 409 and base 411 are threaded toged er to form a hollow receptacle 434 which encloses chamber 435 (see Figure 5). A liquid gasket, commonly referred to as "lock tight", not shown, is poured in the threads 419 and threads 418. This seals the adaptor 409 and base 411 for pressure applications and prevents them from being unthreaded by the user.

A two piece receptacle 434 formed from an adaptor 409, base 411 combination is used for manufacturing reasons. The receptacle 401 shown in the Figures is made from metal (aluminum) and it is easiest to hollow out the adaptor 409 and base 411 from their open ends. It is possible to make a single piece receptacle 4 1 using blow moulding or oti er such techniques. The material and dimensions of d e receptacle 4 1 must be selected to withstand the pressures of the particular application; pressure of 1200 PSI are ouside design limits for a wide variety of air conditioning applications.

Threads 423 correspond to threads 425 on plug 427 of end cap 429. Threads 425 of die end cap 429 also correspond to tiireads 417 of d e injector 403 and are the same as threads 416 of die adaptor 409. Similarly, threads 423 are the same as threads 39 and correspond to tiireads 416.

Seals 431, 433 are similar to seal 12 described previously.

In operation, as shown in Figure 5, seals 431, 433 are placed in the opening to body 407 and the aperature 421. The receptacle 401 is threaded to the injector body 403 and die cap 429. In this way, the effective capacity of the injector 403 is increased. Dye, oil or

other liquids, not shown, can be added through the aperature 421 (when the cap 429 is removed) until the injector 403 and receptacle 401 are filled. The cap 429 is then threaded to the receptacle 401 in die same manner that cap 13 is threaded to injector 1.

The reservoir 401 saves having to use separate injectors for different desired capacities. Injectors are fairly expense components, particularly where a window is used. Although a reservoir 401 may be used for injecting dye, it is particularly useful for injecting refrigerant oil where larger amounts of liquid are typically used.

These advantages are multiplied by using a set of reservoirs 401 in different capacities. For example, reservoirs 401 with 2 ounce, 4 ounce and 6 ounce capacities would allow for 2, 3, 4, 5, 6, 7, and 9 ounce capacities when used alone or piggybacked by threading one reservoir 401 to another between the injector 403 and cap 429. Previously, 7 different injectors would be used to allow for each of tiiese different capacities. The reservoirs 401 are not restricted simply to these sizes; these are examples only. The savings are particularly significant when greater capacity injectors are desired.

As shown in Figure 6, different effective reservoir 401 sizes can be created using base 411 and a set of different sized adaptors 409 A, 409B and 409C. For example, adaptor 40 A when combined witii base 411 may create a 2 ounce capacity chamber 435; adaptor 409B and base 411 may create a 3 ounce capacity; and, adaptor 409C and base 411 may create a 4 ounce capacity. Although only one base 411 is shown in Figure 6, it is understood tiiat a base 411 would be provided for each adaptor 409 in this application. Larger permutations and combinations are possible witii greater numbers of adaptors 409 and bases 411, and greater variety in the sizes of the adaptors 409 and the bases 411.

It is possible to provide reservoirs 401, adaptors 409, bases 411, and injectors 403 separately or in sets. For pressure applications it may be desirable to provide assembled sealed reservoirs 401 ratiier than require the user to perform the assembly or permit the user to use the reservoir 401 without a proper seal between adaptor 409 and base 411.

It will be understood by tiiose skilled in the art that this description is made with reference to the preferred embodiment and that it is possible to make other embodiments employing the principles of the invention which fall within its spirit and scope as defined by die following claims.