Dry cleaning apparatus for cleaning pieces of fabric

A dry cleaning apparatus for pieces of fabric such as clothing has a tumbler drum with a washing space within it in which the clothing is firstly washed with solvent and thereafter is dried and if necessary aired. To this end the drum space with the clothing therein is firstly joined up with a solvent circulation system and then with a hot air circulation system. The solvent circulation system has a filter unit within it for cleaning the solvent and the air circulation system has an air cooler with a condensate trap and furthermore an air heater. For drying the dirt in the filter unit air is branched off from the hot air circulation system at a point downstream from the air heater so that while drying is taking place part of the hot air makes its way through the filter unit and then comes out of the filter unit and by way of a second branch duct goes back into the hot air circulation.

FIELD OF THE INVENTION 
The present invention relates to the dry cleaning of pieces of fabric such 
as clothing, and more specifically to a way of undertaking such cleaning 
in which the pieces of fabric are placed in a processing space, such as a 
tumbler drum, and are first washed with a solvent for washing and 
dissolving out the dirt thereon, the solvent being circulated through the 
clothing and through a filter outside the tumbler, whereafter the input of 
solvent to the tumbler is turned off, the tumbler is drained of solvent 
and the clothing or the like is acted upon by a second circulated fluid, 
that is to say hot air, so that the solvent still in the clothing is 
evaporated and may be recovered from the hot air current by condensation. 
In such a plant the dirt filter unit has to be cleaned, or the filter 
cartridge therein replaced, from time to time. 
BACKGROUND OF THE INVENTION 
In a more limited sense, the present invention has to do with a dry 
cleaning apparatus for use in such a cleaning process and with a cleaning 
plant for the dry cleaning of pieces of fabric as for example clothing, 
the apparatus having a processing space formed by a turning tumbler or 
tumbler drum which is joined up with a solvent circulation system and a 
hot air circulation system, whose operation takes place after that of the 
solvent circulation system, each such circulation system having a pump 
therein. Furthermore the solvent circulation system has a dirt filter, 
whereas the hot air circulation system has an air cooler with a condensate 
trap and an air heater coming after the air cooler in the direction motion 
of the air. 
Such plant is known in the art. In such a plant or apparatus, the dirt 
washed out in the washing operation is kept back and taken up by the 
filter unit so that, dependent on the design of such unit, the filter unit 
has to be cleaned or the filter cartridge therein has to be taken out and 
a new one put in its place. In this case, in the prior art, for example in 
an apparatus having an "expander filter", the first step is to take out 
the filter cake produced, and to put it in a still vessel with the solvent 
from the solvent circulation system, the still forming part of a solvent 
processing and recovery unit so that the solvent may be recovered for 
further use. In the distillation process using the still, dyes and 
bacteria, for example, are cleared from the solvent. 
However, the outcome of such processing is that the still or distillation 
apparatus becomes dirty so that work of disposing of the dirt is not made 
any simpler but only undertaken in a different part of the apparatus. In 
other cases in which throw-away filters, made for example of paper, are 
used, there are still troubles in connection with disposal of the used 
filter papers, inasfar as there will in all cases still be a certain 
amount of solvent in the dirt sticking to the filter paper so that, for 
safeguarding the environment, it is not possible for the filters simply to 
be thrown away and they have to be taken care of by special organizations 
as chemical waste, this being complex and expensive. 
SUMMARY OF THE PRESENT INVENTION 
The invention has to do with such shortcomings in the prior art and one 
purpose or object of the invention is that of designing an apparatus of 
the sort noted, which makes it possible for the dirt from the filter or 
the filter cartridge itself to be disposed of without undesired effects on 
the environment and without the filter or dirt having to be specially 
transported from the apparatus to some special tip for chemical waste. 
A still further purpose of the present invention is to make this possible 
in the simplest possible way. 
For effecting this purpose, and further purposes, in the present invention 
a first air duct is branched off from the hot air circulation system at a 
point downstream from the air heater, such duct running to the inlet side 
of the filter unit, and the outlet side of the filter unit has a second 
air duct running therefrom to the hot air circulation system. 
With apparatus designed on these lines it becomes possible, at the time 
cleaning is taking place, for a part of the hot air current to be branched 
off from the condensing unit, and run though the filter unit, while the 
pieces of fabric are being dried and while the solvent is being evaporated 
off, with the outcome that the solvent in the filter unit and in the 
filtered-out dirt, is evaporated and taken along with the hot air current. 
The dirt and the dirty filter cartridges no longer have to be processed as 
chemical waste or refuse. Because hot air is in any case "on tap" in the 
apparatus, the changes needed in such apparatus for putting the teaching 
of the invention into effect are very simple. 
Further details and general teachings of the invention will be made clear 
using the account now to be given of one working example thereof, to be 
seen in the figures.

DETAILED DESCRIPTION 
The apparatus of FIG. 1 is used for the dry cleaning of pieces of fabric as 
for example clothing. In the housing 1 of the apparatus there is a tumbler 
or cleaning drum 2, which is supported in the housing 1 so that it may be 
turned about a horizontal axis and the pieces of clothing put into its 
inside space 3 tumbled and washed. The pieces of fabric firstly undergo a 
process step in which they are washed with a solvent for dissolving out 
and washing out the dirt in the fabric. To this end the processing space 3 
is joined up with a solvent circulation system 4. This system 4 includes a 
solvent tank or container 5, from which the solvent is pumped by a pump 7 
by way of a pipe 6. Coming out of the pump, the solvent then makes its way 
to a filter unit 8 with a filter cartridge or element 9 through a pipe 10 
joined up with the inlet side of the filter unit 8. The solvent makes its 
way into the inlet side of the filter unit and goes through the filter 
cartridge 9, in which the dirt washed out from the clothing by the solvent 
is deposited. Thereafter the solvent makes its way out of the outlet of 
the filter unit 8 and goes through a pipe 11, forming part of the solvent 
circulation system, to the tumbler drum 2, into which the solvent is run 
axially, the solvent nextly flowing out of the drum housing 1 by way of 
its outlet 12 to a fluff filter 13 and then back into the tank 5. 
When the washing operation has run to an end, the supply of solvent to the 
processing space 3 is cut off and the fabric in the drum 2 spun, the 
solvent centrifuged from the fabric running off into the solvent tank 5. 
At one and the same time the solvent makes its way out of the filter unit 
8 back into the tank 5, this being by way of the pipe or duct 11 or, 
dependent on the special design of the system, by way of the pipe or duct 
10. 
The processing space 3 is joined up with a further circulation system, that 
is to say with a hot air circulation system, through which hot air makes 
its way through the drum 2 and a drum housing head 14. After the washing 
and spinning, the clothing in the drum 2 is acted upon by this hot air 
current, the rest of the solvent therein being evaporated. The hot air 
current comes out through a top radial outlet 15 of drum housing 1 from 
the processing space 3, goes through a further fluff filter 16 and then 
comes back into the processing space after flowing through an air cooler 
17, an air heater 18 joined up with the outlet side of the air cooler 17 
and a top radially pointing inlet 19. The air cooler 17 has a condensate 
trap 17a to take up the solvent condensing here out from the hot air 
current. The outcome is that the air, after being heated up again in the 
air heater, comes back into the processing or washing space in a condition 
free of solvent. The hot air current is produced by a second pump, which 
is placed in the housing head 14 between the fluff filter 16 and the air 
cooler 17, and of which only the motor 20 will be seen in the figure. 
After this stage of the dry cleaning process the dried pieces of fabric are 
aired with circulated air or with air taken in from outside the dry 
cleaning apparatus, and to this end the drum housing 1 has a fresh air 
intake door 21, marked in broken lines, that is opened up after the drying 
operation, while the pump with motor 20 is kept turned on so that the 
fresh air makes its way through the outlet 15 into the head 14. Here the 
circulated or fresh air is moved through the fluff filter 16 and the air 
cooler 17 so that, once again, any solvent still in the air will be 
cleared from such air by condensation. The air, after this cleaning stage, 
is then let off to the outside by blowing through an outlet or discharge 
door 22 between the air cooler 17 and the air heater 18, it being clear to 
the reader that the door 22, like the door 21, is kept shut in the process 
stages coming before this part of the process. 
The dirt filter unit 8 has to be cleaned from time to time or the cartridge 
9 therein changed for a new one. There is however some trouble in this 
connection inasfar as the dirt washed out of the clothing or the like will 
be soaked in solvent, so that for the reason of safeguarding the 
environment the filter cartridge 9 may not simply be thrown away or 
cleaned, for example by washing it. If no special steps are taken, the 
dirt has to be handled as chemical waste, that is to say processed in line 
with special public health regulations. 
In order to make this part of the process simpler, after washing, but while 
evaporation of the solvent out of the processing space 3 is still taking 
place, a part of the hot air current is branched off and ducted through 
the filter unit 8 so that the solvent in the collected dirt and in the 
filter unit, is evaporated and is cleared by the hot air current. In this 
respect the said part of the hot air current is tapped at a point 
downstream from the position at which condensation takes place, that is to 
say downstream from the air cooler 17, and goes to the filter unit 8. The 
branch point is furthermore placed downstream from the air heater 18 in 
the hot air circulation system, so that the clean air coming into the 
filter unit will be hot air. The air makes its way along an air duct 25 
branching off from the head 14 of the housing and joining up with the 
inlet side of the filter unit 8. This air duct 25 may be shut down and is 
in fact shut off in the washing operation. A valve 26 is used for this 
purpose. 
It will be seen that there is a second air duct running from the outlet 
side of the filter unit 8 back to the hot air circulation system so that 
air is ducted into the processing space 3. This second air duct is formed 
in the present working example by the pipe 11 running from the filter unit 
8 to the space 3, such pipe forming part of the solvent circulation system 
and having a two-fold function: while washing is going on it is 
responsible for transporting the solvent, and when the washing stage has 
run to an end and the solvent circulation system has been turned off, the 
hot air current, which is branched off from the air drying the clothing to 
the filter for drying the same, goes through the pipe 11. In this way the 
filtered-out dirt is changed into a dried condition so that the filter may 
be simply thrown away as normal waste, or if it is question of a permanent 
filter, the same may be cleaned on the spot and does not have to handed 
over to a special organization for disposal. The drying of the dirt is a 
very simple operation, because generally speaking it is only necessary to 
make use of the air duct 25. Furthermore the prior art apparatus may be 
changed in its design for use in the invention quite straightforwardly. 
Another point is that the drying of the dirt or of the filter takes place 
at the same time that the clothes are being cleaned so that there is no 
loss of time. Once the cleaning process has run to an end, it is only 
necessary to take out the filter and throw it away. 
In order to be quite certain that the dirt is completely freed of all 
solvent, it is possible in addition to let air into the filter unit 8 from 
the room in which the apparatus is placed, such air coming out of the 
filter unit 8 and making its way into the processing space 3. In the 
present working example of the invention this is done at the same time as 
the airing of the pieces of clothing or other fabric within the processing 
space 3, as has been detailed hereinbefore. This operation is again 
undertaken without causing any loss of time, and furthermore, because the 
circulating air is let into the processing space 3, which is acted upon by 
the aspirating effect of the pump with motor 20 or fan or the like, the 
same moving the air for ventilating the clothing in through the drum 
housing door 21 and driving it out again by way of the outlet door 22, no 
further pumps or fans or the like are necessary, and it is only necessary 
to have a connection, for example in the form of an intake door 27 marked 
in FIG. 1 in broken lines, on the inlet side of the filter unit. This door 
is naturally kept shut when the earlier process stages are taking place. 
The two air currents from the room coming in by way of the doors 21 and 27 
for this reason come back into the processing space 3 and are let off 
therefrom by way of the door 22. 
The connections for air from the room, in the form of the doors 21, 22, and 
27, may be actuated at the same time as part of running of the program for 
the cleaning operation. It will be clear that, furthermore, the operation 
of the valve 26 and the operation of the two shut-off valves 28 and 29 to 
be seen in the figure, and any further valves and controllers that may be 
used, will be automatic and will not be by hand. 
FIGS. 2 and 3 are views of a special form of the filter unit 8 in two 
possible conditions of operation. This filter unit 8 has a filter housing 
30 having opening into it: the first air duct 25, the length 11 of pipe 
forming the second air duct and placed downstream from the filter unit 8, 
and furthermore the part 10 of the pipe (forming part of the solvent 
circulation system), that is downstream from the filter unit 8. In this 
respect it is only possible to see in FIG. 2 the opening of the first air 
duct 25 into the filter housing, the air duct 25 being placed on the 
backside (that is under the plane of the figure) of the housing 30. 
Furthermore the pipe 10 of the solvent circulation system is cut up into 
two legs 10a and 10b, which are in the form of hoses or pipes coming 
together at a point near the pump 7 and running, near the filter unit 8, 
on the two sides of the pipe 11 that is placed in the middle. 
The filter cartridge 9, which is flat in form and has a filter plane at a 
right angle to the vertical and may be in the form of a paper element, is 
placed on the funnel-like opening end 31 of the upstream part of the pipe 
11 that is part of the solvent circulation system. The ends or openings of 
the pipes 10 and 11 are placed on the same side of the housing 30, and in 
fact in the present working example of the invention are at the lower side 
32 of the said housing 30 with a fixed distance between them. Furthermore 
the ends or openings of the two pipes 10 and 11 may be joined together and 
separated from each other flowwise by way of a driving part 33 which may 
be controlled from outside the apparatus in such a way that a connector 34 
(which is fixed on the end of the driving part 33) may be moved between a 
position in which a channel therein provides communication between the 
ends of pipes 10a, 10b and 11 (see FIG. 2) and a position in which the 
ends of pipes 10a, 10b and 11 communicate freely with the interior of 
housing 30 (FIG. 3). This connector 34 is placed in the position of FIG. 2 
like a cover on the two ends of the pipes 10 and 11 fluid-tightly, the 
seals necessary in this respect not being shown in the figure. In this 
position it is possible, at the time washing is taking place, for the 
solvent to go by way of the legs 10a and 10b of the pipe 10 into the two 
angled arms 35 and 36 of the connector 34, the two arms being placed each 
to one side of a middle bell-like part 37 and having their ends placed in 
alignment with the legs 10a and 10b. Coming from the arms 35 and 36 the 
solvent makes its way as shown by arrows into the middle part 37 by way of 
openings therein so that the solvent flows come together and at the open 
lower part, which becomes wider in downward direction, make their way to 
the filter cartridge 9. The solvent is filtered thereby and is then 
discharged through the pipe 11. The filter cartridge, which may for 
example be in the form of a plate, is supported on a filter grid 40, which 
for its part is supported on the wall of the pipe 11. The filter cartridge 
9 is fixed in position by the middle part 37 of the connector 34, which is 
a sort of cover and is seated at the edge on the filter cartridge 9 and is 
pushed thereagainst. 
If the outline of the filter cartridge 9 is round, a sealing effect may be 
simply produced by the edge thereof. (It will furthermore be clear in the 
present connection that the wording "flat filter cartridge" is used in the 
sense of a cartridge that may possibly be folded in a zig-zag form, but 
with the body of the cartridge mainly running in a single plane and more 
specially horizontally). 
The driving part 33 is formed by a rod or the like stretching down through 
a hole in the top side of the housing 30 and being joined up resiliently 
with the connector 34 by a spring 41. The connector 34 is pushed against 
the openings or ends of the pipes 10 and 11 by way of the driving part or 
rod 33 or the like. In this respect the connector 34 on the lower end of 
the rod 33 or the like may be air powered or power-moved in some other way 
and controlled from the outside. The control of such motion of the driving 
part so as to get the connector 34 into the position to be seen in FIG. 2 
or into that of FIG. 3, may be produced as part of one step of a program 
for controlling the apparatus. 
When the filter unit is designed in this way there will be only a small 
amount of solvent in it so that the overall amount of solvent needed in 
the apparatus may be kept down. 
Furthermore door 27 for air from the room is hinged on the filter housing 
30, the function of the door having been made clear hereinbefore. In place 
of a door or flap, however, it is furthermore possible to have a short 
pipe-like inlet controlled by a valve. 
Because the openings of the pipes 10 and 11 are placed in the floor of 
housing 30, the solvent will be drained off more or less completely after 
the solvent circulation system has been turned off. 
When the washing and spinning operation has run to an end, the cover-like 
connector 34 is lifted into the position of FIG. 3 so that within the 
filter housing 30 the air duct 25 will be joined up with the pipe 11 
inasfar as the hot air now will be able to make its way down through the 
filter cartridge 9 and the dirt sticking thereto. The hot air which at the 
same time is forced into the opening of the upstream pipe 10 only has the 
effect of forcing the solvent of the solvent circulation system back into 
the supply tank 5 or will be stopped by the shut shut-off valve 28 so that 
there will be no blow off of hot air at this point. At the time the dirt 
on the filter is being dried by the hot air, the door 27 (for letting in 
air from the room) on the filter housing 30 will be still shut. Nextly the 
room air door 27 is opened, and the valve 26 may be shut so that air will 
still go on being forced through the dirt on the filter. 
Lastly it is possible, after such drying of the filter cartridge 9 (which 
may be made for example of filter-quality paper or specially-made 
non-woven fabric) has been completed, the cartridge may be taken out 
through a door in the filter housing 30 and thrown away. Furthermore the 
filter cartridge may be washed and used again. 
It will be clear from FIG. 1 that a blower or other form of pump 43 may be 
placed in the bypass (having the filter unit 8 within it) shunting the hot 
air circulation system, such a blower speeding up the rate of transport of 
hot air through the filter unit 8. In this way it is possible to make 
certain of an even quicker drying of the filter cartridge, the layer of 
dirt thereon, or of a thick filter cake, by the air being forced through 
it. This blower 43 may be placed in the first air duct 25 or - as in the 
working example to be seen in the figure - in the second air duct or pipe, 
formed here by the pipe 11 (of the solvent circulation system) on the 
downstream side of the filter unit 8 and joining the same with the 
processing space 3 in the tumbler drum 2. Of these two possible line-ups, 
the second one may be better because it takes up less space. Furthermore 
in view of the room air door 27 on the inlet side of the filter unit 8, it 
is useful to have the blower 43 in the second air pipe or duct, inasfar as 
when this is so, after drying with hot air, a large amount of air from the 
room is aspirated in by way of the door 27. 
It is furthermore possible for the blower 43 or its motor two be connected 
to the pump having motor 20 or the like of the hot air circulation system 
in such a way that the two are turned off or turned on at one and the same 
time. Lastly it is to be specially noted that the first air duct 25 comes 
to an end at the outlet of the air heater 18 and preferably ends at a 
location within the housing 1 of the apparatus, so that is placed as close 
as possible to the outlet of the heated air, that is to say at the hottest 
point. This is marked in broken lines in the figure.