The present invention relates to article cleaning, and in particular concerns an apparatus and method for the cleaning of and degreasing of engineering components with an organic solvent or a detergent preparation.

Traditional chlorinated hydrocarbon solvents such as 1, 1, 1 -trichloroethane are increasingly replaced by alternative preparations. Whilst these alternatives have certain advantages over 1, 1, 1 -trichloroethane , they typically have a higher boiling point or low flammability which renders them unsuitable for use in a vapour degreasing system. The present invention accordingly seeks to provide for effective article cleaning using a liquid solvent.

According to the invention there is provided article cleaning apparatus comprising a bath for cleaning liquid, means for releasably retaining articles to be cleaned, the retaining means being movable between a first position in which the articles are immersed in the liquid and a second position in which the articles are removed therefrom, and means for drying the cleaned articles whilst the retaining means is in the removed position .

The retaining means may comprise a cage or a basket or a jig.

Preferably the apparatus includes means for heat¬ ing the cleaning liquid and for maintaining the cleaning liquid at a predetermined temperature. The apparatus may further comprise means for agitating the cleaning liquid, for example eduction nozzles. The retaining means may be movable in said first position to facili¬ tate cleaning. Means may be provided for oscillating the retaining means in said first position, and means may be provided for recycling of the cleaning liquid.

The drying means may comprise a series of air jets or air knives. The retaining means may be movable with respect to the drying means, for example by oscillation.

The apparatus preferably includes means for recovering vaporised cleaning liquid. The recovery means may include an extraction system. There may be provided condensing means or a refrigerant coil, and a filter is preferably provided.

Preferably the apparatus incorporates programmable logic control.

The apparatus as described in any of the six

preceding paragraphs is preferably self-contained, in that cleaning and drying may be carried out within the same housing. The housing may be closable to enable automatic operation therein of cleaning and drying, thereby without spillage of cleaning liquid or emission of air containing vaporised cleaning liquid.

According to the invention there is further prov¬ ided a method of cleaning articles comprising providing a bath of cleaning liquid, immersing an article to be cleaned therein, subsequently removing the articles from the liquid and drying the article.

Preferably the method comprises heating of the cleaning liquid prior to immersion of the articles. The liquid may be agitated to facilitate cleaning. The article may be oscillated when immersed in the cleaning liquid .

The article may be dried by a series of air jets or air knives, and may be oscillated during drying.

The method may further comprise recovery of vaporised cleaning liquid after drying.

The cleaning and drying of articles in accordance with the method as described in any of the four

preceding paragraphs may be carried out within the same housing. The method may be carried out automatically within the one housing once the latter is closed, subsequent to location therein of articles to be cleaned, whereby to prevent spillage of cleaning liquid and emission of air containing vaporised cleaning liquid .

The invention further includes a method according to any of the preceding three paragraphs for cleaning articles using a cleaning liquid selected from LOTOXANE, another organic solvent or a detergent preparation.

The invention will be further described for the purposes of illustration only with reference to the accompanying drawings, in which:-

Fig. 1 is a schematic plan view of an apparatus according to a first embodiment the invention;

Fig. 2 is a schematic side view in the direction of arrow A of Fig. 1 ;

Fig. 3 is a schematic section on B-B of Fig. 1 but omitting certain features for clarity;

Fig. 4 is a schematic plan view of an apparatus according to a second embodiment of the invention;

Fig. 5 is a schematic side view in the direction of arrow c of Fig. 4;

Fig. 6 is a schematic end view in the direction of

a r r ow D o f F i g . 4 ; a n d

Fig. 7 is a schematic end view in the direction of arrow E of Fig. 4.

Referring to Figs. 1 to 3 of the drawings, an article cleaning apparatus, particularly suitable for the cleaning and degreasing of heavy engineering components, comprises an outer housing 10 mounted on castors 12. Within the housing 10 is mounted a vessel 14 for a cleaning liquid. The vessel 14 has a dished base with a closable drainage outlet 16 at the lowermost point thereof. A screen 17 overlies the base to allow particulate debris to fall through preventing re-suspension due to turbulent action of eductor nozzles as described hereinafter. An open-topped stainless steel wire basket is mounted within the housing and is movable by a winch (not shown) from a first position 18A in which it is substantially immersed in liquid in the tank 14 and a second position 18B vertically spaced from the first, in which the basket is lifted clear of the liquid. The two positions 18A, 18B represent cleaning and drying positions respectively for articles contained within the basket. The basket is arranged to permit oscillation within the cleaning liquid when in the first position to facilitate cleaning.

A pump and filter unit 20 is in a fluid circuit 22

with the vessel 14 and introduces liquid to the latter through three eductor nozzles 24, two of the eductor nozzles being shown on respective opposed sides of the vessel 14. Liquid is removed from the vessel 14 through an outlet 26 on an end wall thereof, from where the liquid is returned to the pump and filter unit 20.

A cleaning liquid such as LOTOXANE (U.K. Registered Trade Mark) is introduced into the vessel 14 prior to use of the apparatus. Articles to be cleaned are introduced into the basket, which is lowered to the position 18A so that the articles are immersed in the liquid. The pump 20 causes this liquid to circulate into and out of the vessel 14 via the circuit 22, in this example at a rate of 80 litres per minute. The cleaning liquid enters the vessel 14 through the eductor nozzles 24 which induce turbulence within the vessel 14 aiding the cleaning of articles within the basket. The basket is oscillated vertically further to facilitate the cleaning. The cleaning liquid leaves the vessel 14 through the outlet 26 and is returned by the circuit 22 to the pump and a filter unit 20, for example a cartridge filter which filters out particulate matter is 5 microns. The circulating cleaning liquid is heated by means not shown to a temperature appropriate to the cleaning liquid. The fluid flow rate, temperature and duration of the cleaning process may be controlled by a

programmable logic controller (not shown in detail) as is well known in the art, and which is operated by means of a control panel 30 provided on the exterior of the housing 10. The temperature should be within 20°C of the flash point in the case of flammable solvents.

When the cleaning process is complete, the basket is raised from the position shown at 18A to the position shown at 18B by the winch so that the articles contained within the basket are lifted clear of the cleaning liquid in the vessel 14. When the basket reaches the position 18B it enters a drying area 32 of the apparatus. On the apparatus at either side of the basket there is provided a metal plate 34 having a series of slots or holes 36 to form an air curtain. A fan assembly 35 blows air through the slots 36 whereby to produce a series of horizontal air jets or air knives. There can be produced an air velocity of 5500 fm and a volume of 500 cfm. The basket is oscillated vertically in the region of the air jets whereby to effect drying of the components contained within the basket. The drying process is also controlled by the programmable logic controller. Air from the jets is extracted for example by way of a further fan assembly, from the top of the apparatus at outlets indicated at 38 as will be described. The air so extracted contains vaporised cleaning liquid and is passed through a

condensing baffle or refrigerant coil (not shown) to separate the liquid, which is collected and may be returned to the vessel 14. A charcoal activated filter (not shown) may be provided to scrub any fugitive emissions of volatile organic compounds. The clean air is re-circulated to the air intake of the drying fan 35.

An upper part of the apparatus is arranged to provide sloping walls 37 in which are located the outlets 38, and an inwardly directed lip 39 at the upper edge of each wall 37. This arrangement is particularly effective in reducing solvent emissions from the apparatus. Solvent-laden air bypassing the outlets 38 due to boundary layer friction tends to be circulated on reaching the adjacent wall 37 and rim 38 so that it is redirected to the outlet.

Drying of the articles is assisted by latent transfer of energy gained by the articles during immersion in the heated liquid bath. By re-circulation ^■ of the drying air, the same also tends to become warmed, thus further assisting the drying process.

As the drying process takes place vertically above the cleaning stage, the apparatus is particularly compact. The apparatus is simple to operate, being automatically controlled, and provides for

sel -contained solvent recovery and recycling to prevent emission to atmosphere of cleaning liquid, for example by use of the activated carbon filter or other absorption media suitable for the solvent employed. All components susceptible to wetting may be constructed of high grade stainless steel or other material appropriate to the cleaning liquid being used. The apparatus is particularly suited to the cleaning of components using LOTOXANE (U.K. Registered Trade Mark), but may also be used with another solvent or a detergent.

The controller may provide for warning signals or shut down of the apparatus in the event, for example, of pump or fan failure, low level of cleaning liquid or over temperature o f cleaning liquid.

Figs. 4 to 7 show a modified article cleaning apparatus 50. The apparatus 50 has many features similar to those shown and described in Figs. 1 to 3, and like reference numerals are used for these features in Figs. 4 to 7. Referring specifically to Fig. 5, the modified apparatus 50 incorporates an alternative mechanism 54 for raising and lowering the basket. This includes a motor driven lead screw with a carriage for an independent motor. The basket is located on a saddle, which in turn fits a dovetail slide arrangement, A cable is linked to the motor by a cam arrangement and

the saddle whereby to provide for oscillation of the basket. This arrangement can be provided at one end only of the apparatus 50, thereby permitting the provision of appropriate plates and slots 36 for the formation of an air curtain at each of the other three sides of the apparatus. In the arrangement shown in Figs. 4 to 7, appropriate heating means 56 is provided to warm the supply of air from the fan assembly 35 to further assist the drying process.

Modifications may be made within the scope of the invention. The liquid circulation and drying systems may be different from those described and shown. Any desired control and/or monitoring of features may be incorporated. Control features can allow for wash only or dry only programmes in addition to wash and dry.