FR2466563A1 - IMPROVEMENTS ON DRUM WRENCHES - Google Patents

Abstract

The subject of the invention is a drum wringer comprising a substantially hermetic outer casing, air intake and outlet orifices each located in a rear wall of the casing, a rotating drum for the laundry, mounted in the outer casing, a motor mounted radially outside the drum in the outer casing, a fan mounted on the motor shaft and arranged to cause air to circulate, via the air intake, in the casing, forward around the drum and back through the drum, through an outlet in the rear wall of the drum. The air, after passing through the outlet 54 in the rear wall 44 of the drum, passes through an annular duct 60 disposed in a space between the rear walls of the drum and the casing 44, 12, and the fan 114 extends radially towards the air. 'interior partially in said space. (CF DRAWING IN BOPI)

Description

I

  The present invention relates to improvements

  tyme drum wringers with

  an outer casing which is substantially hermetically

  an air inlet and an air outlet, a clothes drum mounted inside the housing so as to be rotatable about a horizontal axis, and a motor mounted in the housing at least partially below the

  drum with a fan mounted on or connected to the

  motor and arranged to pressurize the housing.

  Such drum wringers have already been proposed in British Patent Nos. 1,221,343 and 1,416,881. In the first of these patents, lies

  a particular description of the pressurisation of the car-

  ter and how air is circulated from

  then an inlet port at the front of the housing rearwardly below the drum, penetrating through the rear wall of the drum and exiting through an anterior loading opening of the drum and from there, via ducts, in the door and in

  the top of the crankcase to an exit opening

  térieure. In the second British patent, namely No. 1,416,881, the air flow is through an air inlet port in the rear wall of the casing forward in the housing around the drum up to an air intake opening in the drum at the anterior end and from there rearward through the drum above the laundry and outwardly through an outlet port in the drum on the axis of it and consequently through an outlet

  in the rear wall of the housing.

  In each of these earlier publications, the engine has a horizontal axis and the fan

  is mounted on the motor shaft near the ad-

  mission to the casing. In the case of the patent NI 1.221.343,

  the diameter of the fan is such that it is located

  well below the level of the lowest point of the drum. In the case of British Patent No. 1,416,881, the engine is mounted in a corner of the housing

  but the diameter of the fan is limited by the

  space available by the drum path and in each

  No. of these prior embodiments, the axial position of the fan is limited by the space available by the drum path and in each of these prior embodiments, the axial position of the fan is

  in alignment with a portion of the drum. These limitations

  This leads to a limitation of the size of the fan, which tends to reduce the ability of the system to maintain adequate air circulation against the resistance of a vent pipe or a fan.

  partially clogged filter. In some

  the type represented in British Patent No. 1,416. 881, a variety of expedients

  were used to obtain the air circulation ne-

  necessary. For example, in one case, a two-pole motor is used to drive a small fan, but this requires the use of a reduction system.

  having two belts to drive the drum which adds

  to the complexity and cost of the system.

  In another commercial arrangement, still using a small diameter fan, the realization

  uses the more complicated type of cage fan

  squirrel with a chamber around the ventilator

  in order to obtain acceptable air circulation.

  Even in this case, the power of the heating element

  had to be limited below average in these

drums of drum spinners.

  Although in British Patent No. 1,221,343, the fan diameter is reasonable under

  prediction of adequate height below the drum

  bour, this is not always an acceptable solution, for example, when the wringer has to adapt to a

  washing machine having the same envelope and the same

  door and consequently the height of the drum is im-

  posed by the requirements of the washing machine.

  The main object of the present invention is to provide a relatively simple embodiment which alleviates or solves some of the problems stated above. Thus, according to one aspect of the present invention, a drum wringer has an outer casing which

  is substantially hermetic, except for the charging door-

  laundry, an air inlet and an air outlet, each located in a rear wall

  of the outer casing, a rotating drum for

  in the outer casing for rotation about a horizontal axis, the drum? and the casing presenting

  a space between their rear walls, a motor

  radially outside the drum in the outer casing, a fan mounted on the motor shaft and

  arranged to pressurize the casing by causing a cir-

  culation of air through the air intake, - in the housing, forwards around the drum in and back through the drum, through an outlet

  in the posterior wall of the drum, through the

  annular duct disposed in said space, and

  the air outlet, the fan extending

  partially inwardly in said

pace.

  Conveniently, the rear wall of the drum is supported by a bearing mounted on a support extending transversely between the side walls of the housing, and the rear wall of the housing is removable for

  an interview without disturbing the landing.

  The annular duct is preferably mounted

on the transverse support.

  In order to obtain a control of the dryness obtained

  by the drum wringer, associated stationary and mobile dry contacts are preferably in said space with the one or more movable contacts mounted on the end of the drum facing said space, and being connected to the dryness sensor (s) located in the drum. In this case, the or each movable contact may comprise a curved metal strip of limited circumferential extent, the arc being described around the horizontal axis. Curved tape can expand

about 30 around the axis.

  Conveniently, the contact system includes a pair of stationary contacts and a pair of

  mobile contacts, one of each pair being connected to the

  a pair of detection probes located in the drum. The fan may have two sets of integral blades, one set being arranged to cause said air flow, and the other set being arranged to

  cause a cooling air flow through the

towards the engine.

  Preferably, the second set of blades is arranged

  to cause two air flows to the ventilator

  a flow through the engine and the other around the periphery of the crankcase

of the motor.

  The solution envisaged by the present invention to the problems set out above provides a space between the posterior wall of the drum and the posterior panel.

  of the casing, so that the diameters of the fan

  drum and drum can overlap. From this

  an adequate fan diameter is provided without

  that it is necessary to provide either a maximum height

  Complementary is an increased motor speed. One

  duit is used to convey the exhaust air

  then the back of the drum until an opening in the rear panel of the housing. This duct is also used to form the rear bearing support of the drum. The duct is mounted so that it is

  supported by the casing rather than the posterior panel

  so that it can be removed

  without disturbing the drum and the belt of it.

  This facilitates easy assembly of the drum and

  without the need for additional access panels to adjust the belt on the

  pulleys and also provides easy access for

  nance. In addition, the overall achievement is relatively

  cheap and simple to perform reliably a-

with a minimum of moving parts.

  The invention can be practiced with a

  number of ways, but one embodiment

  particular will now be described, as an example, in

see the attached drawings.

  Figure 1 is a sectional side elevation

  of a drum wringer according to the invention.

  Figure 2 is a posterior elevation of

  the drum wringer of Figure 1, the posterior panel

  being withdrawn and some parts being

cut in sections.

  FIG. 3 is a plan section of the rear part of the drum wringer of FIGS. 1 and 2,

along line 3-3 of Figure 2.

  Fig. 4 is a large-scale sectional side elevation of a portion of Fig. 1 showing in detail the drum bus bar arrangement and resilient contacts for detecting dryness;

linen.

  Figure 5 is a section of one of the drum blades of the wringer showing the method of attachment

  a probe to detect the dryness of the laundry.

  Figure 6 is a schematic rear view of

  than the drum wringer showing the circulation

air.

  Figure 7 is a top view with the tamper

  withdrawn bour showing air moving forward

  from the motor-fan assembly.-

  Figure 8 is a side view of the assembly.

  motor-fan blower showing the air circulation.

  Figure 9 is a circuit of the machine.

  Figure 10 shows the waveform of

voltage at two points of the circuit.

  Figure 11 is a time chart of

  the sequence of operation of a timer

  constituting part of the machine.

  The drum wringer shown on the

  includes an outer casing for hermetically

  to allow the inside of the crankcase to

  be pressurized in a manner that will be described later.

  Thus, the housing comprises a pair of side walls, shown in Figure 3, an anterior wall 11, a removable rear panel 12 attached to flanges

  folded inwardly 14 of the side walls 10 to the

  screw yen 16, a top 18 and a base 20.

  Stretching from one side to the other of the back of the

  casing, inside the rear panel 12, is

  a pair of vertically spaced horizontally disposed support posts 22 and 23 are secured by bolts 24 to the folded edges 14. For rigidity purposes, each of the transverse posts 22 and 23 is substantially U-shaped as shown in FIG. Figure 1. Extending vertically between central regions of the cross uprights 22 and 23 is a vertical bearing support as a whole

  by 28. This includes later parts of

  vertically extending bottom and bottom 30 and 32 respectively which are respectively attached to the two transverse uprights 22 and 23. Between the parts

7 2466563

  and 32, is a part 34 positioned towards the

  in which is mounted a horizontally extending drum support rod 36. As shown in detail in FIG. 3, this rod is mounted by means of a fitting screwed into a threaded collar 28 which is

  rigidly attached to part 34. A blocking nut

  40A ge completes the assembly of the rod. This montage by

  screwing allows an axial adjustment of the position of the

  in order to catch up with a terminal game of mounting a tamper

  rotational stock designated as a whole by 40. The

  The precise details of this drum will now be described with particular reference to FIG.

  a circular or peripheral wall 42, a wall pos-

  44 and an anterior wall 46. The drum

  three horizontally extending blades 48, of which

  one is shown in Figure 1, and by means of

  which the linen is lifted and lowered during the rota-

drum.

  The rear wall 44 of the drum has a perforated central portion 50 extending vertically in which is mounted centrally a bearing 52 by means of which the rear end of the drum is mounted on the support rod 36. The periphery of the central part of the wall posterior 44 is transformed into an axial step 54. A felt seal 56 cooperates with the external surface of this step and also with a rim 58 extending axially from a substantially frustoconical partition 60, whose rear face is

  shown in Figure 2 and which has an opening

  center 62 through which the central part extends

  trale 34 of the upright 28 extending vertically. The or-

  62 is also an exit path for air leaving the drum 40 rearwardly through

  the openings of the central part 50.

  A dome-shaped filter 64, removable, is

  disposed in front of the bearing 52 and is connected to the wall pos-

44 of the drum.

  It should be noted in particular that the rear wall 44 of the drum is spaced a distance

  of the rear panel 12 of the housing, mainly

  by the realization of the rod support 36 and the frustoconical partition 60 surrounding it. The space between

  the posterior wall 44 of the drum and the posterior panel

  12 serves several purposes which will be explained

in more detail later.

  As shown in FIG. 1, at the anterior end of the drum, the anterior wall 46 possesses

  an axial flange 66 delimiting a load opening-

  drum. The flange 66 is supported by a

  number of spaced apart brackets 68 extending

  curved, one of which is shown in Figure 1. These

  they are mounted on a similar axial flange 70 of an envelope 72 of a heating element which is mounted

  stationary way between the anterior wall 46 of the drum

  bour and the front wall 11 of the housing. The casing has another axial rim 74 on which is mounted a ring 76 against the door and which extends forward abutting with an annular portion 78 of the intermediate wall of the housing 11. A door 80 which comes into contact with a seal 82 carried by the annular portion 78 is hingedly mounted.

  around a vertical axis in this area of the crankcase.

  As shown in FIG. 1, a heating toroid 86 is provided between the casing 72 of the heating member and the front wall 46 of the drum and a

  annular heating member 88 is mounted in this torus.

  The periphery of the casing 72 of the heating member.

  is spaced slightly from the drum 40 to constitute

  an annular air inlet 90 for the passage of air

  then the outside of the drum 40 in the torus 86.

  in front of the heating element, the anterior wall

  46 of the drum is provided with perforations in 92 for

  put air backward from the torus 86 and through the drum and above the laundry in the direction of the arrows shown on the

figure 1.

  A motor 100 with short-circuit winding of horizontal axis is mounted on the bottom wall 20

  crankcase in a corner of it, the anterior end

  the shaft of which a pulley 102 is

  a belt 104 surrounding the drum 40. The former

  Posterior tremity 106 of the motor carries a fan generally designated 108 and which is embodied as a plastic molding. The fan has a support plate 110 on the side

  previous of which are mounted cooling blades

  motor 112 and on the rear side of which

  are mounted blades 114 of larger diameter pres-

  cranking the crankcase. In alignment with the fan, the rear panel 12 of the housing is provided with a grid

116.

  In operation, the blades 114 draw air horizontally into the housing through the grid 116 as shown. The air is unloaded from

  centrifugally from the blades 114 and pressurizes the

  seems of the crankcase. The air passes forwards below the drum 40 as well as upwardly behind it

  and from one edge to the other of the top of the drum of the

  Figure 1 shows the air passing through the drum through the torus 90 and then backwards above the laundry, through the filter 64 and the perforated posterior wall portion 50 and from there. through the central opening 62 in the

  frustoconical partition 60 to be unloaded in a deflec-

  120 mounted on the rear of the rear panel 12.

  This deflector directs the air flow vertically,

  for example, in a conduit 122, by which the air of

  exhaust is transmitted to a suitable orifice in order to

  avoid the moist air to be unloaded in the room in

  which operates the drum wringer.

  Due to the permanent use of gold

  During a drying cycle, the machine as a whole tends to heat up and it has been found that the temperature of the air between the casing and the drum is higher than that of the ambient air at room temperature. outside the wringer. An elevation

  150C is typical. This gives rise to difficulties

  if this air is used to cool the

  Therefore, in this embodiment, measures are taken to ensure that the engine is cooled by air very shortly after it has been sucked into the crankcase and before it heats up as a result of a transfer. heat from the body of

  heating, drum, etc. In addition to Figure 1, the

  FIGS. 6, 7 and 8 also show the direction of the air flow caused by the fan 108. The main blades 114 cause a flow of the type

  radial position shown in FIG.

  the engine-fan assembly in a corner of the

  casing, the air is also unloaded-in the same way as

  Figure 7 along one side of the housing and also below the motor, as shown in Figure 1 and Figure 8. Fan blades

  112 cooling the engine also cause a

  outflow that causes low pressure

  in the region 160 around the tree 106, as shown

  1 and 7. It will be seen that the fan blades 112 have end portions 162 arranged to closely overlap the rear end of the motor 100 and these tend to cause a low

  164. As a result, a

  Backward air flow is caused both through the engine in the direction indicated by arrows 166 in FIG. 8 and around the periphery of the engine as indicated by the arrows 168 in FIG. he

  two air flows tend to suck air from

  shot of a power supply that has just moved forward from the fan and as a result,

  this air is still relatively cold, if not at the same time.

  room temperature. Accordingly, satisfactory engine cooling is provided by air which is not substantially heated, if at all, by heat transfer from the drum and the heater.

  In particular, it should be noted that

  1 and 2 that the outer diameter of the blades 114 of

  fan is greater than the space below the tani-

  40 inside the housing and as a result, the

  the 114 of relatively large diameter and thus-allows the obtaining of adequate pressures and air flows inside the system against the resistance of the ventilation pipe or con-ducts or a filter

  partially clogged without sacrificing power. nominal

  the heating element, which in this example is 2.5 kW. This is contrary to some earlier proposals in which the diameter of the fan

  had to be such that it fits under the drum,

  thus avoiding a reduction of the air flow with the result that in order to overcome the back pressures 2.5 due to ventilation pipes or the like and to clogged filters, the nominal power of the heating element was reduced to 1.7 kW or less, which is well below average. This, of course, is

  translated by prolonged drying times for the esso-

reuse as a whole.

  A supervisory body is provided between the

  drum and a circuit of the machine in the

  to control the dryness of the dried linen by the manufacturer.

  China. Basically, the system includes sound

  3-5 spaced apart inside the drum of the machine which are periodically connected to the circuit in a way that scra dre written farther. The variation.- r-r. the second between the probes com.mande a period initi, a3 heating of indeterminate hard. Event -.nt,] The probes and the circuit detect a dryness of the order of 15c, .-, after which a period of heating diterminated

  Manuellenient is expected to complete the drying of the

to the desired degree of dryness.

  Referring to Figure 1, the lintérieua of

  drum has three longitudinal blades 48 urifc? é-

  spaced, one of which is shown, and mounted

  on one of these blades is a pair of probes es-

* paced 130 each of which is of the form represents in detail in Figure 5. Thus, each probe comprises fLn

  metal element 131 substantially V-shaped, .onz-

  on an insulating support element 132 and maintained in

  position on the blade 48 by means of a bolt 134 is

  extending through a plastic support sleeve

  than 136 on the outside of the blade 48. The bolt pzszE-

  a head 138 through which the metal element 131 of the probe is electrically connected to a terminal 1k4 on the outer end of the bolt 134 and by which the probes are connected to the circuit in a manner i will be described with reference to Figure 9. Since the probes 131 obviously rotate with the drum, it em%

  necessary to provide a sensor device which is

  killed in the space between the posterior wall 44 of the drum

  and the rear panel 12 of the casing

  shown in FIGS. 1, 2 and 4. The terminals 140 of the two probes 131 are respectively connected by pins

  (not shown) to a pair of bus bars

  142 and 144, each of which has a curved stainless steel band, the arc of which is described around the axis of the rotary drum, each band having a pair

  ends folded inwards 146 by means of

  it is mounted on an insulating support block 148 fixed to the end wall 44 of the drum by means of screws 150 shown in FIG. 4. It can be seen in FIG. 4 that the two bus bars 142 and 144 are

  spaced axially from one another and that they cooperate

  with rotary elastic contacts 152 and 154, respectively. It can be seen that the contacts 152 and 154 are mounted on another insulating support block 156 which is fixed to a flange 157 extending axially forwards from the vertically lower rear part 32 of the bearing support 28, as shown on FIG.

Figure 4.

  To illustrate how the resistance variation

  between the probes 130 controls the operation of

  the machine, Figure 9 represents the parts concerned

  of the machine circuit, while FIG. 10 illustrates the waveforms appearing at different points of the circuit, and FIG.

  of time diagram, the sequence of operation of

  do not timer part of the machine.

  The circuit of the machine comprises a circuit de-

  200 which is connected to the probes 130, and which controls

  of a relay 202 which has a single contact normally

  open 202-1. As long as the laundry in the drum

  boom of the wringer has a higher moisture content

  At approximately 15%, Relay 202 remains inactive, and half

  nuterie, which is powered by a motor 204, remains

  de-energized. During this phase, of course, the

  100 and the heating element 217 are excited. Lors-

  that the moisture content of the laundry has fallen to about%, the relay 202 is energized and the timer motor 204 is energized via the contact 202-1, so that the timed portion of the operating cycle

of the machine now begins.

  During this part of the operating cycle, the excitation of the motor 100 and the heating element

  217 is continued for a period which is

  completed by the user, and can be up to about 43 minutes. At the end of this period, the heating element 217 is de-energized, but the motor 100 continues to rotate for another 10 minutes, cooling the

  laundry lying in the drum. This completes the

  cycle, the laundry should now be dried to the desired degree. The remaining part of the cycle lasts about 1 hour, during this part of the cycle, the motor is excited briefly, once a minute, to tumble the laundry and help prevent a development

  folds. The linen can, of course, be removed to a -

  moment during this last phase since

is already dry.

  The details of the operation of the circuit detect

will be described later.

  The timer has a first cam that turns

  constantly at 1 rpm as long as

  timer 204 is energized, and commands an interruption.

  206; as shown in FIG. 11, the switch 206 is closed for 3 seconds during each turn of

  This switch 206 controls the excitation

  Termitten the motor 100 during the final part of the machine cycle. The timer also has five other cams, which rotate together in 60 hops of 60, and control five switches 208, 210, 212, 214 and 216. The switch 208 controls the period between

  leaps made by the cams, by non-recom-

  shown in the figures; as shown in Figure 11, for most of the time, the period between hops is 2 minutes, but from position 21 to position 26, the period between hops is only 30 seconds.The group of five cams is connected at a command button,

  by which the cams can be advanced manually

  in any desired position.

  The switch 210 controls the power supply of the

  most parts of the machine, although two lamps-

  neon witnesses 218 and 220 take their dietary

  The switch 210 is closed in all positions of the timer cams, except for the last position, the position 60, so that it isolates itself from the mains, and not through the switch 210.

  the main parts of the machinery, including the

  timer 204, when the machine cycle has been

completely completed.

  The switch 212 controls mainly, the chufúant element 217, the interlocker 214 controls the

  motor 100 which causes the drying drum to rotate

  tion, and Interrupteur 216 conreals the engine of

  terie 204, with detection circuit 200 'Er..on. cnnemen: * the machine is started by closing a mains power switch 222, in ferman ia po'e the machine, so that a micro-

  switch 224 actuates by -a door is closed, and in fact

  to advance the group of five timer cams, which would have stopped in the ostio 60 at the end of the previous cycle9 in an intermediate position between

  position 1 and 'The posit'or. 25, depending on the degree of sicci-

  The desired line of the switch 222 directly energizes the lamp 218 indicating that the machine is running. Closing the microswitch

  224 and the inumery 210 delivers energy through the

  a thermostat 211 that includes con-

  thermostatically controlled high and low temperature tem-

  21 and 215 respectively and a separate switch

  up / down reader 219, and through the intermediary of

  Switch 212 to heater 217. Switch 212 is a three-position switch, constituting a switch with a central off position; for any cam position from position I to position 26, switch 212 is closed to supply energy to heating element 217, but the heating element is de-energized for all other positions

  of cam. During a final part of the cycle, the interrup-

  Ieur 212 is a replacement conductive path,

  whose role will be explained later.

  Closing the microswitch 224 and the minute

  terie 210 also delivers energy, through

  intermediate switch 214, the motor 100; Inter-

  switch 214 is closed for all positions of

  me from position 1 to position 31. So, we see

  until the cam group moves to the position

  26, the heating element 217 and the motor 100 se-

  will be continually excited (subject to the control of the heating element by the thermostat) and drying

laundry will run normally.

  As explained above, the minute engine

  204 does not rotate until the moisture content

  laundry has fallen to about 15%. The final dryness of the laundry is set by appropriate manual adjustment of the timer cams, thereby setting the time that elapses from when the timer motor is energized until the timer goes to the position.

  26. When moving to heading 26, the heating element

  ghost is de-energized and the heating phase of the cycle

ends.

  The end of the heating phase is controlled

  by a combination of resistance detection and half-

  nutage, rather by resistance detection only, since the variation in resistance with the variation in moisture content is much greater at a moisture content of 15% than when the linen approaches total dryness. Also, the moisture content declines fairly quickly in the range just below

  15%; that's why the timer pro-

  faster bunting during positions 21 to 26. An error of one position in the manual setting of the timer cams would have a considerable effect on

  the final dryness of the linen if it resulted in a continuation

  the heating phase for 4 minutes instead of

  2 minutes after the timer motor 204 has started

  to turn. For longer timer periods

  corresponding to lower moisture content

  a mistake of 2 minutes can be tolerated. The maximum period before the timer switches to

sition 26 is about 40 minutes.

  After position 26, the motor 100 continues to rotate the drum, and the fan 108 blows

  cold air in the cooling drum.

  When switching to position 31, after 10 more minutes

  At the same time, the switch 214 opens to de-energize the motor 100. At the same time, the switch 212 closes the aforementioned replacement conductive path. This path connects the indicator lamp 220 to the neutral pole of the power supply, through the heating element, so that the lamp

  lights to indicate that the laundry is ready.

  The switch 206 is connected in parallel

  switch 214, to control the main motor

  100. Obviously, it has no effect as long as the switch 214 is closed, but once the switch 214 is open, the switch 206 has

  effect of exciting the motor 100 for 3 seconds each

  that minute. This will tumble the laundry briefly, and help

  to prevent wrinkling.

  A buzzer 226 is connected, in series with an on / off switch 228, between the neutral pole of

  the pilot lamp 220 and the phase wire of the main engine

  pal 100. Thus, when the indicator lamp 220 is on,

  indicating that the laundry is ready, a closure of the

  switch 206 to energize the motor 100 will also briefly sound the buzzer 226, signaling that the

  linen is ready. If a buzzer alarm is not

  If necessary, the switch 228 is open.

  This stage of the cycle, with intermittent tumbling, will continue for about 60 minutes, after which the timer cams will have reached position 60,

  and the timer motor 204 will stop.

  The detector circuit 200 is supplied with energy

  via switch 216 for all

  the cam positions from position 1 to position 26.

  A power supply 230 delivers a low DC voltage from the energy supplied via

  the switch 216. The detection circuit 200 con-

  is essentially a capacitor C3, across which the voltage varies depending on the moisture content of the laundry, a detection transistor TR3 which controls the voltage across the capacitor C3 and a Schmitt trigger controlled by the transistor TR3, and comprising

  transistors TR1 and TR2, in the emitter wires

  in common of which is connected the relay coil

202.

  In operation, the probes 130 are connected during a fixed period during each revolution of the drum.

  drying, two terminals 232 and 234 of the circuit de-

  tection. During this period, the resistance of the laundry in contact with the probes forms, with a resistor R7, a voltage divider connected across the DC supply. The midpoint of this voltage divider is

  connected, via a diode D3, to the condensation

  C3. When the probes 130 are not connected to the terminals 232 and 234, the diode D3 is polarized in the direction

  reverse, and the voltage on capacitor C3 drops

  because this capacitor is connected by

  intermediate a resistor R5 of high value at the base of the transistor TR3. During the period during which the probes 130 are connected to the terminals 232 and 234, the diode D3 is forward biased, and a weak

  Current flows in capacitor C3, raising again

  its tension in a quantity which depends on the resistance

  Accordingly, the voltage on the capacitor C3 will be a sawtooth, and in this case the voltage on the capacitor C3 will be a sawtooth.

  conditions of steady state, the upper limits

  re and lower of the voltage excusrion will be linked direc

  the resistance between the probes 130 and consequently

  the moisture content of the laundry.

  The transistor TR3 has a resistance of

  transmitter constituted by a potentiometer R3, the cursor of which is connected to the base of transistor TR2, which constitutes the input of the Schmitt rocker. As long as the moisture content of the laundry is greater than about%, the voltage on the slider of the potentiometer R3, which

  voltage on capacitor C3, will never drop

  but low enough to block the transistor TR2. The values

  their resistances in the Schmitt flip-flop are chosen so that the resulting current across the transistor TR2 is insufficient to drive the relay 202. However, when the moisture content has dropped below about 15%, the limits The lower of the voltage excussion on the capacitor C3, as repeated by the transistor TR3, will be low enough to block the transistor TR2 and drive the transistor TRI. The current in the transistor TRI is sufficient to actuate the relay 202, so that the motor of

  timer 204 starts to turn, as described above.

  Once the Schmitt seesaw has changed

  state, as described above, Relay 202 will remain

  until the power supply is disconnected from

  detection 200. This will occur when the

  nuterie will go to position 26; after this position,

  the switch 216 delivers energy directly to the

  timer 204, ensuring that the timer completes

its cycle.

  If the capacitor C3 is brought back to the positive end of the power supply, the transistor TR3 will hardly drive when power is restored, which ensures that when the machine is restarted, the relay

202 will not be pressed.

  The detection circuit 200 also comprises a resistor R10 which, by closing a switch 236, can be connected in parallel to the resistor R7. This changes the moisture content at which the relay 202 will be operated at perhaps 30%, so that

  It is possible to dry the laundry at a "meal dryness-

  The sensing circuit 200 also includes various components, such as capacitors C4 and C2, and diodes D1 and D2, which serve to suppress a

  interference or to protect-the transistors junctions.

  These components are not essential to an understanding

the operation of the circuit.

Claims (8)

  1) Drum wringer with outer casing   which is substantially airtight except for the laundry loading door, an air inlet and an air outlet each located in a rear wall of the housing, a rotating drum for the laundry   mounted in the outer casing for a rotation   turn of a horizontal axis, a motor mounted radially to   the outside of the drum in the outer casing, a   tilator mounted on the motor shaft and arranged to   crank the housing causing air to circulate, through the air intake, into the housing, forward around the drum and back through   the drum, through an exit in the posterior wall   drum, characterized in that the air, after passing through the outlet (54) in the rear wall   (44) of the drum, passes through an annular duct (60)   placed in a space between the posterior walls of the drum.   b and the housing (44, 12), and in that the fan (114) extends radially inward partially in said space.   2) Drum wringer according to claim 1,   characterized in that the air outlet orifice is   killed in the rear wall of the housing in alignment with the axis of the drum.   3) Drum wringer according to claim 1   or 2, characterize that the posterior wall of the drum   bour is supported by a bearing (52) mounted on a sup-   port (22, 23) extending transversely between   side of the housing, and the rear wall (12) of the housing is removable to allow maintenance without disturb the landing.   4) - drum wringer according to claim 3, characterized in that the annular conduit (60) is mounted on the transverse support. 2-466563   ) Drum wringer according to one of the claims   tions, characterized by contacts of   stationary and associated mobile stations (154, 144)   killed in said space with the one or more movable contacts (144) mounted on the end of the drum facing said space, and being connected to one or more sensors   dryness (130) located in the drum.   6) Drum wringer according to the claim, characterized in that the or each movable contact   has a curved metal strip (144) for   limited circumferential circumference, the arc being described   round the horizontal axis of the drum.   7) Drum wringer according to claim 6, characterized in that the curved strip extends over around 300 around the axis.   8) Drum wringer according to one of the claims   5 to 7, characterized by a pair of contacts   stationary and a pair of movable contacts, a   tact of each pair being connected to one, different,   a pair of probes located in the drum.   9) Drum wringer according to one of the claims   tions, characterized in that the ventilation   has two sets of blades, one set (114) being   arranged to cause a flow of cooling air dissement through the engine.   Drum wringer according to claim 9,   characterized in that the second set of blades is a-   set to cause two air flows to the   fan, a flow being made through the   and the other around the periphery of the engine crankcase.