Apparatus For Degreasing Objects By Means Of A Solvent

Abstract

An apparatus for removing grease, oil and fat from articles consists of means for boiling a solvent so that the vapor fills a chamber in which the cool articles are placed. The wall of the chamber is designed as a lid which can be lifted for facilitating the insertion and removal of the articles. A spraying means for liquid solvent is arranged in the upper part of the treating chamber to spray liquid solvent over the articles.

Description

The invention relates to an apparatus for degreasing objects by means of a solvent, more specifically an apparatus of the type comprising a chamber for liquid solvent, a heating means to bring the liquid solvent to the boil, and a treating chamber for the objects to be degreased, the treating chamber being in communication with the chamber for the liquid solvent so that it can be filled with steam from the solvent which then condenses on the relatively cool objects. The solvent condensed in this way dissolves grease and oil on the surface of the objects and then streams off the objects. A chlorinated hydrocarbon is preferred as solvent, such as trichloroethylene or tetrachloroethylene, or a fluorochloro-hydrocarbon, for example, trichlorotrifluoroethane.

When the temperature of the objects has increased to that of the steam, of course, no further condensation takes place. Objects with much grease on the surface may therefore be incompletely cleansed. Attempts have been made to solve this problem by alternately immersing the objects in liquid solvent and subjecting them to steam from boiling solvent. Such treatment requires a lifting means for the objects. The object of the present invention is primarily to provide an apparatus in which the objects do not need to be moved while they are being alternately treated with liquid and vaporized solvent. In this way extremely large or heavy objects can be simply degreased. Another object of the invention is to keep the consumption of solvent low.

The apparatus according to the invention is characterized in that the wall of the treating chamber is constructed as a lid or hood which is removable from the apparatus, that a lifting means is arranged to raise the lid for the insertion and removal of objects in the apparatus, and that a spraying means for liquid solvent is arranged in the upper part of the treating chamber to spray liquid solvent over the objects. The solvent which is sprayed over the objects should have a temperature which is lower, suitably by at least 10.degree. than the boiling point of the solvent. The liquid solvent may thus be permitted to contain dissolved grease and oil which is removed during a subsequent vaporization treatment.

According to a preferred embodiment the spraying means consists of cooling pipes on which the steam of the solvent condenses and the condensate flows down on to the objects. Since the condensate consists or pure solvent, the degreasing process can in this case be completed with a treatment with liquid solvent.

The invention will now be described with reference to the accompanying drawings in which:

FIG. 1 and 2 describe two embodiments of the apparatus according to the invention.

The apparatus according to FIG. 1 comprises a lower part 1 having a chamber 2 for liquid solvent, a heating means 3 by means of which the solvent can be brought to the boil, and a perforated bottom 4 for the objects 12 to be degreased. The apparatus also comprises a lid 11, open at the bottom, which can be raised and lowered by means of a cable 5 which is would onto a winding drum 6 driven by a motor 7.

The lower edge of the lid 11 is situated in a liquid lock formed by a lower wall 8 and a sidewall 9 which is double and can be cooled by cooling water supplied through a pipe 13 with a valve 14 and which is drawn off through a pipe 15. The liquid solvent which collects in the liquid lock flows down into the chamber 2 through openings 10.

The lid 11 forms a treatment chamber 30 for the objects 12. In the upper part of the treatment chamber 30 is a spraying means in the form of cooling pipes 16 to which cooling water is supplied through a pipe 18 with a valve 19 and withdrawn through a pipe 20. The pipes 18, 20 are attached in the lower part 1 of the apparatus and also have the function of supporting the cooling pipes 16. On the lower side of the pipes 16 are ridges or spikes 17 from which the condensed solvent flows and is thus evenly distributed over the objects 12.

In the upper part of the treatment chamber 30, above the cooling pipes 16, a thermostat 21 is arranged to start a timer 22 when the thermostat 21 senses a temperature which is equal to or lower than the temperature of the solvent steam. The timer 22 is joined to a contactor 23 which closes and breaks the current to the motor 7, and to a magnetic control device 24 which controls the valve 19.

On the lid 11 is a peg 25 which cooperates with a limit position switch 27 which controls the valve 14 via a magnetic device 28. On the upper part of the lid 11 is a ventilation conduit 29 in the form of a flexible tube 29. This is connected to a fan 55 driven by a motor 56. The current to the motor 56 is connected and disconnected by a contactor 57 controlled by the above-mentioned limit position switch.

The apparatus according to FIG. 1 operates in the following manner. The objects 12 inserted in the apparatus are first subjected to vapor degreasing, the steam from the boiling solvent in the chamber 2 rising and condensing on the cold objects 12. The condensate with dissolved grease flows down into the chamber 2. When all the objects 12 have reached the temperature of the steam, the steam rises further past the cooling pipes 16 (the valve 19 is kept closed) and reaches the thermostat 21, which then emits a signal to the timer 22. The timer emits a signal to the magnetic control device 24 to open the valve 19 so that the cooling water can flow to the cooling pipes 16. The steam condenses on the cooling pipes 16 and the condensate flows down onto the objects 12 and dissolves the grease which has not been removed during the vapor degreasing.

When this degreasing with liquid solvent has continued for a desired period, which is set on the timer 22, the timer emits a signal to the magnetic device 24 to close the valve 19 and a signal to the contactor 23 to start the motor 7. When the lid 11 starts to be lifted the peg 25 actuates the breaker 27 to emit signals both to the contactor 57 to start the fan motor 56 and to the magnetic device 28 to open the valve 14. The wall 9 will thus be cooled, so that at the moment when the lower edge of the lid leaves the liquid in the liquid lock the solvent vapor will flow through the openings 10 and condense on the wall 9. The cooling capacity of the wall 9 is suitably maintained so high that all steam developed from the solvent condenses on this wall. This means that the level of the solvent vapor in the lid 11 will fall from the cooling pipes 16 to the openings 10 so that a corresponding quantity of air is drawn in through the ventilation tube 29.

The lid 11 is lifted so far that its lower edge is above the cooling tubes 16, after which the degreased objects 12 are removed in horizontal direction and new objects inserted. In order to facilitate the handling of the objects, the perforated bottom 4 may be constructed as a roller conveyor. The lid 11 is then lowered, upon which the peg 25 actuates the breaker 27 to close the valve 14 and stop the fan motor 56, and the process is then repeated.

The valves 14 and 19 with their control devices thus make it possible to save cooling water in comparison with if the wall 9 and pipes 16 were permanently cooled.

In the apparatus according to FIG. 2 corresponding parts have been given the same designations as in FIG. 1. The apparatus according to FIG. 2 includes a cooler 41 situated in the lower part 1 of the apparatus and fed with cooling water through a tube 42 provided with a magnetically controlled valve 43. Cooling water is withdrawn through a tube 44. The cooler 41 replaces the cooled wall 9 in the apparatus according to FIG. 1. The condensate from the cooler 41 is collected in a trough 45 and led through a conduit 46 to a chamber 47. This chamber 47 is in communication with a pump 48 which, via a conduit 49, pumps the solvent to a spraying means in the form of perforated tubes 50 in the upper part of the treating chamber 30. The solvent flows down from the spraying means 50 over the objects 12 and is collected in the chamber 47. The timer 22 is in communication with a contactor 51 for the motor to the pump 48, a contactor 52 for the heating means 3 and a magnetic device 53 to control the valve 43.

The lid 11 according to FIG. 2 is provided at the top with a filter 58 containing active carbon. The filter can be blown clean by steam which is supplied through a conduit 59 and can be dried with air supplied through a conduit 60. The filter communicates through a flexible tube 61 with a cooler 62 in which the mixture of water vapor and solvent vapor formed during the cleaning process condenses. The condensate flows to a separator 63 where the heavier solvent departs through a tube 64 and the lighter water through a tube 65.

The arrangement according to FIG. 2 is also provided with a ventilation drum 66 surrounding the liquid lock 8, 9. The drum 66 communicates with a fan, not shown, through a tube 67. Air is drawn in through a gap 68 at the upper edge of the wall 9. This ventilation prevents solvent from the liquid lock from coming out into the working premises in the form of vapor, and exercises a cooling effect on the wall 9. The ventilation drum 66 and the fan are suitably so dimensioned that they can take care of the entire quantity of solvent vapor which may be developed by the boiler 3 upon a fault in the apparatus.

The lid 11 in FIG. 2 is provided with a safety breaker in the form of a peg 69 which, when the lid is raised, actuates a breaker 70 which disconnects the current to the boiler 3 by means of the contactor 52. Boiling can thus only take place when the lid is lowered.

The apparatus according to FIG. 2 operates in the following manner. During the vapor degreasing the valve 43 is closed and the pump 48 out of operation. When the vapor reaches the thermostat 21 the timer 22 is started and emits a signal to the contactor 51 to start the motor for the pump 48. The comparatively cool solvent from the container 47 is now sprinkled over the objects 12. After a predetermined interval the timer stops the motor for the pump 48 and emits a delayed signal to the contactor 52 to disconnect the current to the heating means 3 and similarly emits a delayed signal to the magnetic device 53 to open the valve 43. The steam in the treating chamber 30 condenses primarily on the objects 12 and rinses off any remains of oil and the like, and then on the cooler 41. The lid 11 is then raised and the objects 12 replaced, after which the process is repeated.

In the description of the drawings it has been assumed that one degreasing with vapor and one with liquid is sufficient. In difficult cases, however, the objects may of course be subjected to several treatments with vapor and liquid alternately.

The spraying means 16, 50 may alternatively be permanently fixed in the lid 11 itself. The supply of liquid to the lid and its removal from the lid is then suitably carried out by means of flexible hoses of such length that the lid can be raised.

Due to the closed construction of the apparatus the losses of solvent will be minimal. Evaporation from the liquid lock is slight, and the air leaving through the ventilation tube when the steam from the solvent rises in the apparatus contains hardly any solvent, and this can be recovered as described in connection with FIG. 2.

Claims

What is claimed is:

1. An apparatus for degreasing objects by means of a solvent, comprising wall means forming a support (4) for the objects to be degreased, a lid (11) having a top wall and sidewalls extending downwardly from said top wall and arranged to fit over and about the support for said objects with the lower edge of said sidewalls of said lid located below the support, the support and said lid forming a treating chamber (30) for the objects, said wall means forming a chamber (2) for liquid solvent located below the support, heating (3) in communication with the chamber for the liquid solvent arranged to bring the liquid solvent to a boil, said wall means providing communication for the vapor of the boiling solvent between the chamber for the liquid solvent and the treating chamber, means (16) for spraying liquid solvent being located in the upper portion of the treating chamber above the support for spraying liquid solvent over the objects, lifting means (5-7) secured to said lid for raising said lid so that objects can be placed on and removed from the support, means (9,41) in communication with the chamber for the liquid solvent for condensing the vapor of the boiling solvent while the lid is in its raised position, said means for condensing the solvent vapor being located below the support (4) and said wall means forming a liquid lock (8,9) arranged to receive the lower edge of said sidewalls of said lid, the liquid lock arranged to receive liquid solvents condensed upon the walls of said lid, and said wall means providing overflow openings (10) for conveying the excess of liquid solvents within the liquid lock into the chamber (2) for the liquid solvent. 2Apparatus according to claim 1, characterized in that the means for spraying liquid solvent consists of cooling pipes (16) on which the steam of the solvent condenses, and the condensate flows down on to the

objects. 3. Apparatus according to claim 2, characterized by a magnetically controlled valve (19) in a supply conduit (18) for delivering coolant to the cooling pipes (16), a thermostat (21) in the upper part of the treating chamber (30) being arranged to emit a signal to open the valve (19) when the solvent steam has risen above the cooling pipes (16).

. Apparatus according to claim 3, characterized by a timer (22) connected to the thermostat (21) and arranged to reclose the valve (19) after a

predetermined period. 5. Apparatus according to claim 4, characterized in that the timer (22) is arranged after the termination of the predetermined

period to start a motor (7) to raise the lid (11). 6. Apparatus according to claim 2, characterized in that stays attached to the lower part of said apparatus being arranged to support said means (16) for spraying liquid solvent, and said stays comprising tubes (18) in the form of cooling pipes

for supplying cooling water to said means for spraying liquid solvent. 7. Apparatus according to claim 1, characterized in that said means for condensing the vapor of the boiling solvent comprising a portion of said

wall means forming the liquid lock. 8. Apparatus according to claim 1, characterized in that a ventilation conduit (29) is arranged in communication with the top of the lid (11), and a fan (55) connected to

the ventilation conduit. tubes (50) 9. Apparatus according to claim 7, characterized by a valve (14) operated supply conduit (13) for supplying coolant to the wall means (9), and by a breaker (27) which is arranged to be actuated by the lid (11) to open the valve (14), suitably via a

magnetic device (28), when the lid (11) is raised. 10. Apparatus according to claim 1, characterized in that the means for spraying liquid solvent consists of tubes (50) having nozzles and a pump (48) to supply liquid solvent to the tubes, and that a thermostat (21) in the upper part of the treating chamber (30) is arranged to emit a signal to start the pump (48)

when the solvent steam has risen above the tubes (50). 11. Apparatus according to claim 10, characterized by a timer (22) connected to the thermostat (21) and arranged to stop the pump (48) again after a

predetermined period. 12. Apparatus according to claim 11, characterized in that the timer (22) is arranged, with a delay after the pump has stopped, to break the heat supply to the heating means (3), and after a delay to open the cooling water supply to a cooler (41) situated below the

treating chamber (30). 13. Apparatus according to claim 1, characterized in that a ventilation means (66-68) is arranged in said wall means forming the liquid lock (8) to prevent steam from the solvent from coming out into

the working premises. 14. Apparatus according to claim 1, characterized in that the lid (11) is connected at the top to a filter (58) containing

active carbon. 15. Apparatus according to claim 14, characterized in that the filter (58) is provided with supply conduits (59,60) for steam and air and is connected to a cooler (62) and a separator (63) to recover the

solvent. 16. Apparatus according to any of claims 1, characterized in that the lid (11) is arranged to actuate a safety breaker (70) which permits heat to pass to the heating means (3) only when the lid (11) is in its operating position.