FR2736943A1 - STOPPING POSITIONING PROCESS OF A ROTATING PART MOVED BY A UNIVERSAL MOTOR, IN PARTICULAR OF THE DRUM OF A WASHING MACHINE LOADING FROM THE TOP, AND IMPLEMENTATION DEVICE - Google Patents

Abstract

The positioning device of the invention is applied in particular to a washing machine to position its drum when stationary so that its gate faces the upper opening of the machine. It essentially comprises a magnet (4) fixed on the pulley (1) of the drum, cooperating with a flexible reed switch (5) fixed on the frame. The switch is connected to a microprocessor (6), controlling a pulse control circuit of the universal motor (2) of the drum.

Description

The present invention relates to a stationary positioning method

  a rotary part driven by a universal motor, in particular the drum of a top-loading washing machine, and

  to a device for implementing this method.

  In a top-loading washing machine, it is preferable that at any time during an operating cycle, in particular at the end of the treatment cycle, generally after the last spin or after drying, the drum s stops in such a way that its gate is just opposite the upper opening of the machine, so that the user can

  remove or add laundry without having to turn the drum by hand.

  Drum positioning devices with asynchronous motors are known, but these devices cannot be used with a

  so-called universal type motor, which is generally used in today's washing machines.

  Positioning devices operating with a universal motor are also known, these devices comprising either

  mechanical locking means of the drum, or Hall effect sensors.

  These solutions are too expensive to be able to be implemented in

  washing machines produced in large series.

  The present invention relates to a positioning method when a rotating part is stopped, driven in rotation by a universal motor, in particular the drum of a top-loading washing machine, making it possible to stop this drum. so that its door stops facing the upper opening of the machine (the one by which the laundry is introduced and taken out) in practically all cases of use, as quickly as possible. The present invention also relates to a device for

  implementation of this process, the device which is as inexpensive as possible.

  The method according to the invention consists in locating the stopping point of the rotating part using an electrical output sensor, and from the start of the stopping phase of the part's engine, cutting its supply and send it controlled pulses of current, substantially evenly spaced, of increasing durations until detection of passage at the breakpoint, then reversing the direction of rotation if the part has not stopped at the desired position and sending it other substantially regularly spaced current pulses, of increasing durations, and so on until stopping at the desired position. If, at the end of a determined period of time after the start of the stop phase, the stop is not obtained at the desired position, a second positioning phase is commanded which applies to the motor another series of pulses of increasing duration, with possible change of direction of rotation at each passage through the desired position, and the sending of these pulses is stopped when the part is as close as possible to the desired position, or when this part passes for the first time

  of this second phase by the position sought.

  The device for implementing the method of the invention applied to a machine comprising a rotary part driven in rotation by a universal motor, comprises a position or presence sensor, a first part of which is fixed on the rotary part and the second on the support of the rotating part, facing the first part when the rotating part is in the desired stop position, a processing circuit connected to one of the parts of the sensor, and an engine control device, connected to the sensor and comprising circuits for producing current pulses of duration

variable.

  The present invention will be better understood on reading the

  detailed description of an embodiment, taken by way of example not

  limiting and illustrated by the appended drawing, in which: - Figure 1 is a simplified schematic view of a washing machine according to the invention; FIG. 2 is an example of a timing diagram of signals detected in the machine of FIG. 1, under normal conditions, - FIG. 3 is another example of a timing diagram of signals detected in the machine of FIG. 1 in the presence of a strong laundry unbalance

in this machine.

  The present invention is described below with reference to a lavelinge, but it is understood that it can be implemented in other types of machines or equipment requiring precise positioning when the parts driven are stopped. rotation, for example a dryer

  top loading drum.

  In FIG. 1, only the parts of the washing machine have been represented.

  linen necessary for understanding the invention, namely the pulley I of the machine drum, its universal drive motor 2, and the belt 3 which connects them. A magnet 4 is fixed on the pulley 1, near its edge, and a flexible blade switch 5 is fixed on the frame of the machine.

  so that it is right in front of magnet 4 and as close as possible to it

  ci when the door of the drum carrying the pulley 1 is just opposite the upper opening of the washing machine. The switch 5 is connected to an input of a microprocessor 6. This microprocessor is either the one equipping the machine, when this is the case, or a processor dedicated to the positioning function of the drum. The microprocessor 6 is connected to a circuit 7 for controlling the motor 2. This circuit 7 is a power circuit which controls, in a manner known per se, under the control of the microprocessor of the machine, where it exists, or of a electromechanical programmer, the different engine speeds (start, stop, reverse direction of rotation and different speeds). For the purposes of the invention, the microprocessor 6 also controls the circuit 7 by making it send motor 2

  variable width current pulses, as described below.

  Referring to Figure 2, suppose that at an instant to the microprocessor program 6 begins the drum positioning phase, for example after the last spin of the laundry contained in this drum. Suppose that at this instant the drum stopped so

  that the magnet 4 is far from the switch 5. This switch 5 is therefore open.

  The microprocessor 6 goes to a first subroutine which then controls the sending by the circuit 7 of controlled pulses (allowing speed regulation) to the motor 2. The first of these pulses is referenced II. The duration of this pulse It is for example around 200 ms, and it makes the motor 2 rotate by a certain angle. Suppose that after 11, the magnet 4 is still distant from the switch 5. After a period of approximately 1 s after 11, sufficient to allow the drum to stabilize at standstill, the microprocessor 6 commands the sending at time tl by circuit 7 of a second pulse 12 of duration 200 + 200 = 400 ms approximately. Suppose that after 12 the drum stabilizes at stop without the magnet 4 passing in front of the switch 5. After a period of approximately 1 s after 12, the microprocessor 6 commands, at time t2, the sending of a third pulse 13 to the motor 2. The progression of the durations of the pulses being arithmetic, of reason 200 ms approximately, the duration of 13 is therefore 400 + 200 = 600 ms approximately. Suppose that shortly after sending 13 the magnet 4 passes in front of the switch 5 at time t3, but that the inertia of the motor + drum assembly causes the latter a little beyond the

  angular stop position sought.

  The transient closing of the switch 5, taken into account by the microprocessor 6, causes it to pass to a second subroutine which commands the reversal of the direction of rotation of the motor 2 and the sending, about 2 seconds after t3, to the instant t4, of a pulse 14 with a duration of about ms. It is assumed that shortly after t4, at time t5, when the drum stabilizes at stop, the magnet 4 is opposite the switch 5 which closes definitively. In this case, the microprocessor 6 ends the positioning program, and can advantageously report this fact by

  commanding the lighting of an appropriate indicator.

  If, after 14, the magnet 4 does not reach the switch 5, the microprocessor 6 commands the sending of another pulse, similar to 12, and so on until the closing of the switch 5. If this closure is final, the positioning program stops. Otherwise, said first

  subroutine is called again, and so on.

  In order for the microprocessor to easily detect the passage of the magnet 4 in front of the switch 5, the rotation speed of the drum must be relatively low (for example less than rpm), so that the pulse produced by the transient closing of the switch when the magnet passes has a width sufficient to be

  taken into account by the electronic circuits of the microprocessor.

  If the laundry in the drum is poorly distributed and has a high imbalance, the positioning program may take a long time to stop the drum at the right angular position, or even fail to do so. To avoid this, the invention provides, according to an advantageous aspect, to limit, for example to about one minute, the search phase. At the end of this period of time, if the desired positioning is not obtained, we

  can either temporarily stop the positioning program described above

  above and order a short phase of re-distribution of laundry in the drum (a few alternating slow rotations followed by a short rotation at high speed, for example) and immediately order a second phase of distribution, similar to the first, either pass immediately to a second distribution phase, and be content in the event of a second failure, with an approximate positioning, that is to say a stop at approximately + 10 from the desired position. Within this angular limit, the user can see the door of the drum through the upper opening of the machine, and turn the drum by hand to bring it to the desired position. Such a case is illustrated in FIG. 3 o, at the end of the first positioning phase P1, lasting approximately one minute, ending at time T'1, the position

  desired is not obtained. Immediately afterwards begins the next phase P2.

  At time '12, the switch S closes temporarily, that is to say that the drum slightly exceeds the desired breakpoint. The positioning program is immediately stopped, because there is then a high probability that

  the drum has just passed the desired stopping point.

Claims (9)

  1- Positioning method when a rotating part (1) is stopped, driven in rotation by a universal motor (2), characterized in that it consists in locating the stopping point of the rotating part at using a sensor (4,5), with electrical output, and from the start of the engine shutdown phase of the part, cut off its supply and send it controlled current pulses (11, 12, 13 ) substantially evenly spaced, increasing in length until detection of passage to the breakpoint, then reversing the direction of rotation if the part has not stopped at the desired position and sending it other current pulses substantially regularly spaced (14), of increasing durations, and so on until stopping at the position sought.   2- Method according to claim 1, characterized in that if, at the end of a determined period of time after the start of the stop phase, the stop is not obtained at the desired position, a second command is ordered positioning phase which applies to the motor another series of controlled pulses of increasing duration, and we stop sending these   pulses when the part passes through the desired position.   3- A method according to claim 1, characterized in that if, after a determined period of time after the start of the stop phase, the stop is not obtained at the desired position, a second command is ordered positioning phase which applies to the motor another series of controlled pulses of increasing duration, with change of direction of rotation at each passage through the desired position, and the sending of these pulses is stopped when the part is as close as possible to the desired position.   4- Method according to one of claims 1, 2 or 3, characterized   the current pulses have respective durations of approximately 200 ms, 400   ms, 600 ms, ...., according to an arithmetic progression of reason 200 ms.   - Method according to one of the preceding claims,   characterized in that the pulses are spaced approximately 1 s apart.   6- Method according to one of claims 2 to 5, characterized in that   that said determined period of time is approximately 1 min.   7- Method according to one of the preceding claims,   characterized in that the first pulse (14) sent after detection of passage through the desired stop position, without stopping in this position, is   sent approximately 2s after this detection.   8- Method according to one of claims 2 to 7 for the application   a washing machine for laundry, the rotating part of which is its drum, characterized in that if the laundry in its drum has a high imbalance, a re-distribution of the laundry is carried out before ordering   the second positioning phase.   9- Positioning device at the stop of a rotary part (1) driven in rotation by a universal motor (2), characterized in that it comprises a position or presence sensor of which a first part (4) is fixed on the rotating part and the second (5) on the support of the rotating part, facing the first part when the rotating part is in the desired stop position, a processing circuit (6) connected to one of the parts of the sensor, and a motor control device (7), connected to the sensor and comprising circuits for producing current pulses at variable duration.   - Device according to claim 9, characterized in that the position or presence sensor comprises a magnet (4) and a flexible blade switch (5).   11- Washing machine characterized in that it comprises a device for   positioning of the drum according to claim 9 or 10.