FR2668852A1 - PRESSURE SWITCH FOR THERMAL SAFETY OF A WASHING MACHINE OR ANALOGUE APPARATUS. - Google Patents

Abstract

The pressure switch has an internal chamber (24) with a member such as a membrane (7), sensitive to pressure and acting on electrical contacts (13,14,15). The chamber (24) is connected to an external volume (2), the pressure of which is to be controlled, by two connecting pipes (18,19) mounted "in parallel", to improve the safety function. Particular application: thermal protection for washing machine.

Description

I "Pressure switch for the thermal safety of a washing machine or appliance

  The present invention relates to a pressure switch, that is to say a thermal safety device having an internal chamber with a member, such as a membrane, sensitive to pressure and acting on

  at least one electrical contact, the chamber being connected to an external volume

  the sensing element such as diaphragm deforms or moves under the influence of pressure variations, and opens or closes electrical contacts, inserted in suitable protection circuits, as soon as the pressure to be controlled is transmitted to said chamber. that pressure

limit is reached.

  A pressure switch of this type can be used as a safety device, for example in a washing machine, in which case the pressure switch is connected to a compression chamber, which is itself connected to the washing machine tank. The contacts of the pressure switch thus complement the thermal protection of the washing machine, and they can be

  mandatory for compliance with safety requirements.

  Usually, the pressure to be controlled is transmitted to such a pressure switch by a single pipe If this single pipe is closed or pinched, the pressure switch can no longer perform its safety function It is possible

  avoid this inconvenience by doubling the entire security system, that is,

  say by providing two pressure switches or a dual body pressure switch, as well as

  that two respective connecting pipes, and possibly two volumes

  my distinct from o leave these two pipes This solution is heavy,

expensive and cumbersome.

  The present invention aims to eliminate these disadvantages by providing

  a technical solution which avoids the use of a second pressure switch and a second compression chamber in the washing machine or other apparatus to be controlled, while considerably limiting the risks resulting from a clogging or pinching of a transmission hose

pressure.

  For this purpose, the subject of the invention is a pressure switch of the type specified in the introduction, which comprises at least two connection pipes mounted "in parallel" between the external volume, the pressure of which is to be controlled,

  and the internal chamber with pressure sensitive member.

  Thus, in case of closing or pinching of one of the pipes, it is still practically certain that the other pipe can properly transmit the pressure to the aforementioned chamber, so that the

  pressure switch remains able to perform its safety function.

  The internal chamber of the pressure switch can be delimited, in known manner, by a housing cover and a membrane constituting the pressure-sensitive member; in this case, according to one embodiment of the invention, the housing cover comprises two end pieces for connecting the respective ends of the two pipes whose other ends are connected to the external volume

whose pressure is to be controlled.

  In the case of the application of the invention to the thermal protection

  washing machine, the external volume to which the laundry is connected

  tooth the two pipes is a single compression chamber, itself

  connected to the tub of the washing machine.

  In any case, the invention will be better understood by means of the

  description which follows, with reference to the single figure of the schematic drawing

  annexed representative, by way of non-limiting example, a form of execution

of this pressure switch.

  This figure is a sectional view of a pressure switch according to the present invention, applied to a washing machine or other similar household appliance The pressure switch itself, generally designated by the mark 1, is connected to a chamber of compression 2,

  itself put into communication via a tubular connection

  3 with the tank 4 of the washing machine, for which a control

is necessary.

  In known manner, the pressure switch 1 comprises a support housing 5, closed by a cover 6 A membrane 7 has its periphery clamped between the support housing 5 and the cover 6, while its central part rests on a movable disc of thrust 8 subjected to the action of a spring 9 of

  adjustment of the engagement pressure The force of the spring 9 is itself

  even adjusted by means of a screw 10 Inside the housing-support 5 is mounted a bistable mobile mechanical assembly 11, connected to a fixed terminal 12 and carrying an electrical contact 13 which can be multiple; the movable contact 13 cooperates with at least one normally closed fixed electrical contact 14 and a normally open fixed electrical contact,

  a set screw 16 to act on the position of the latter con-

  tact 15 to adjust the reclosing pressure Finally, a stop 17

  ensures safety in case of bonding between contacts 13 and 15.

  According to the invention, the pressure switch 1 is connected to the compression chamber

  2 by two pipes 18 and 19 The first pipe 18 is connected at one end to a first nozzle 20 of the cover 6 of the pressure switch 1 and, at its other end, to a first nozzle 21 of the compression chamber 2. 19 is connected at one end to a second end piece 22 of the cover 6 of the pressure switch 1 and, by its other

  end, to a second endpiece 23 of the compression chamber 2.

  Thus, the two pipes 18 and 19 are connected "in parallel" and normally transmit one and the other, towards the pressure switch 1, the pressure that prevails inside the compression chamber 2 This pressure

  is brought into the chamber 24 delimited by the lid 6 and by the

  brane 7, and it acts beyond a certain threshold, via the thrust disk 8, on the bi-stable mobile assembly 11, to modify

the state of the contacts 13,14 and 15.

  If one of the two pipes 18 and 19 is accidentally closed or pinched, the other pipe always ensures the transmission of pressure from the chamber 2 to the pressure switch 1, and the latter still provides its safety function, responding to any dangerous rise in pressure,

  in particular to provide thermal protection.

  It goes without saying that the invention is not limited to the sole embodiment of this pressure switch which has been described above, by way of example;

  it embraces, on the contrary, all the variants of implementation and application

  cation in accordance with the same principle It is thus, in particular, that one would not depart from the scope of the present invention by modifying the constructive details of the pressure switch, such as the arrangement or the number of electrical contacts, or by destining this pressure switch to one use

  other than the safety of a washing machine.

Claims (3)

  1 pressure switch comprising an internal chamber (24) with a member (7) responsive to pressure and acting on at least one electrical contact (13, 14, 15), the chamber (24) being connected to an external volume (2), the pressure to be controlled is transmitted to said chamber, characterized in that it comprises at least two connection pipes (18, 19) mounted "in parallel" between the external volume (2) whose pressure is to be controlled   and the inner chamber (24) with pressure sensitive member (7).   2 pressure switch according to claim 1, wherein said chamber   (24) is delimited by a housing cover (6) and by a member   brane (7) constituting the pressure-sensitive member, characterized in that the housing cover (6) has two end pieces (20, 22) for connecting the respective ends of two pipes (18, 19) whose other ends are connected to the external volume (2) whose pressure is to be controlled.   3 pressure switch according to claim 1 or 2, characterized by its application to the thermal protection of a washing machine, said external volume (2) being a compression chamber itself   connected (in 3) to the tank (4) of the washing machine.