EP2770101A1

EP2770101A1 - Laundry machine

Info

Publication number: EP2770101A1
Application number: EP13156301.7A
Authority: EP
Inventors: Alessandro Cecco; Paolo Driussi
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2013-02-22
Filing date: 2013-02-22
Publication date: 2014-08-27
Anticipated expiration: 2033-02-22
Also published as: EP2770101B1; WO2014128226A1; PL2770101T3

Abstract

A laundry machine (100) for treating laundry items is proposed. The laundry machine (100) comprises a drum (110) adapted to house the laundry to be treated, a motor (120) arranged for rotating the drum, and a control system (210) adapted to adjust the operation of the laundry machine at least partially based on acquired operating information. Said control system (210) comprises at least one speed sensor (310) adapted to provide an electrical signal containing information on a rotating speed of the motor (120), and at least two electrical connection elements (317a, 317b) adapted to electrically connect the speed sensor (310) to a control unit (150) for transferring the electrical signal from the speed sensor (310) to the control unit (150). Said control unit (150) is operable to receive said electrical signal and adjust the rotating speed of the motor (120) accordingly. In the solution according to an embodiment of the present invention, the control system (210) further comprises at least one electrical coupling member (325) adapted to electrically interconnect said two electrical connection elements (317a, 317b) for preventing said two electrical connection elements (317a, 317b) from acting as a receiver of electromagnetic fields permeating the laundry machine (100). In addition or alternatively, the control system (210) further comprises a failure-check apparatus (430) connected to either one of said two electrical connection elements (317a, 317b), the failure-check apparatus (430) being adapted to provide to the control unit (150) an electrical signal identifying a failure condition in which at least one of said two electrical connection elements (317a, 317b) and/or the speed sensor (310) is subjected to a malfunction.

Description

The present invention relates to laundry machines, such as laundry washing machines, laundry washing/drying machines both for domestic and professional use. More particularly, the present invention relates to a laundry machine comprising means for preventing malfunctions thereof.
A household and/or professional laundry machine - such as a laundry washing machine and a laundry washing/drying machine - typically comprises a washing tub, enclosed in a casing, that houses a rotatable drum in which the laundry can be loaded/unloaded, and accessible by a user for loading/unloading the laundry through a loading/unloading aperture selectively closable by a door.
The operation of the laundry machine comprises various operation phases. For example, initially washing liquid (e.g., water or water mixed with washing/rinsing products) is introduced in the tub of the laundry machine by means of an inlet hydraulic system fluidly connected to the tub and is heated up to a predetermined temperature. Subsequently, a washing phase starts in which the laundry previously loaded into the rotatable drum is washed thanks to the chemical reactions exerted by the washing liquid, supported by the tumbling action caused by the rotation of the drum. At the end of the washing phase the washing liquid is drained from the tub into an outlet hydraulic system and the laundry may be rinsed and spin-dried. Finally, in washing/drying machine, a drying phase may be started, during which the laundry is properly dried by forcing a hot and dry air stream into the tub and throughout the laundry. Preferably, one or more operating parameters (e.g., target washing liquid/drying air temperatures) of the operating phases may be set by a user through a user interface, provided for this purpose, in the laundry machine.
In order to correctly perform the operating phases just mentioned, the laundry machine is advantageously provided with a plurality of electric/electromechanical elements (e.g., a heater) adapted to perform one or more of such operating phases (e.g., heating the washing liquid), which are generally controlled by a control system (e.g., comprising a microcontroller, sensors and ancillary circuitry such as conditioning circuits). The control system actuates the electric/electromechanical elements according to predetermined set of instructions (e.g., stored in a memory device) associated to a laundry treating cycle (e.g., each designed for a peculiar of textile type) selectable by a user (e.g., through the user interface) and/or operating information acquired from one or more sensor element (e.g., a temperature sensor) comprised in the control system.
The rotating speed of the drum is subjected to several changes while the laundry machine performs one among various selectable laundry treating cycle. Thus, the operation of a (electric) motor that imparts rotation to the drum is carefully controlled by the control system. A speed sensor element (e.g., a tachometer dynamo), for measuring the rotation speed of a rotor shaft of the motor, is usually connected to the control unit through suitable electrical connection elements (e.g., wires). Since the drum motor is usually housed in a bottom position inside the casing while the control unit is usually placed in a top position of the casing, such electrical connection elements are usually quite long (generally they have a length in the order of the meter). The speed sensor element provides a control unit (e.g., comprising a microcontroller and possibly conditioning circuit) of the control system with an electrical signal indicating the motor rotating speed (for examples, a tachometer dynamo provides an electrical signal having an oscillating frequency proportional to the rotating speed of the motor shaft). As known, this electrical signal is used by the control unit to adjust the operation of the motor and therefore the rotating speed of the drum.
Unfortunately, a failure condition may occur in which the speed sensor element and/or the electrical connection elements are subjected to a malfunction and electrical signals indicating the motor rotating speed are no more provided to the control unit. For example, this malfunctions may comprise, in a non limiting way, events such as a break down of the speed sensor or of an electrical connection element, or a disconnection of the speed sensor element and of one of the electrical connection elements one from the other or from the control unit. Moreover, during this failure condition the open-circuited electrical connection elements may start to act as a receiver antenna, absorbing electric energy from electromagnetic fields permeating the environment in which the laundry machine is placed, and therefore the laundry machine itself, and converting such electric energy into spurious electrical signals; for example, electromagnetic field(s) produced by the alternating voltage from the Mains may be received by the electrical connection elements. In such cases, the control unit is fed with no electrical signals or with spurious electrical signal at fixed fundamental oscillating frequency (i.e., typically 50 or 60 Hz) of the alternating voltage and/or oscillating at harmonics and/or sub-harmonics frequencies thereof, which may be misinterpreted by the control unit as corresponding to a motor rotating speed. Therefore, the control unit receives the spurious electrical signals at fixed-frequency or no electrical signals at all, independently from the actual rotating speed of the motor. This may lead to a situation in which the control unit indefinitely increases the rotating speed of the motor, and consequently of the drum (for reaching a desired rotating speed), since there is no electrical signals (i.e., interpreted as idle motor condition by the control unit) or no change in the frequency of the spurious electrical signal received by the control unit. This situations are likely to cause serious drawbacks such as motor malfunctions due to uncontrolled rotating speed thereof, damages to the drum and/or to the tub for the uncontrolled rotating speed, and resulting oscillations, of the drum and damages to the laundry (loaded in the drum) being treated. Moreover, an excessive rotating speed of the drum may cause the laundry machine to move, possibly damaging neighboring items (such as pieces of furniture), which may be hit by the laundry machine during such movement.
The Applicant has tackled the problem of devising a satisfactory solution able to provide a laundry machine robust against failures of the speed sensor element and/or the electrical connection elements and able to identify such a failure thereof.
The Applicant has found that by providing a coupling member adapted to interconnect the electrical connection elements together it is possible to prevent the spurious electrical signal from arising and at the same time a failure-check check apparatus allows identifying the failure condition of the speed sensor element and/or the electrical connection elements; therefore, the drawbacks mentioned above are substantially timely avoided.
One aspect of the present invention proposes a laundry machine for treating laundry items is proposed. The laundry machine comprises a drum adapted to house the laundry to be treated, a motor arranged for rotating the drum, and a control system adapted to adjust the operation of the laundry machine at least partially based on acquired operating information. Said control system comprises at least one speed sensor adapted to provide an electrical signal containing information on a rotating speed of the motor, and at least two electrical connection elements adapted to electrically connect the speed sensor to a control unit for transferring the electrical signal from the speed sensor to the control unit. Said control unit is operable to receive said electrical signal and adjust the rotating speed of the motor accordingly. In the solution according to an embodiment of the present invention, the control system further comprises at least one electrical coupling member adapted to electrically interconnect said two electrical connection elements for preventing said two electrical connection elements from acting as a receiver of electromagnetic fields permeating the laundry machine. In addition or alternatively, the control system further comprises a failure-check apparatus connected to either one of said two electrical connection elements, the failure-check apparatus being adapted to provide to the control unit an electrical signal identifying a failure condition in which at least one of said two electrical connection elements and/or the speed sensor is subjected to a malfunction.
In an advantageous embodiment of the invention, the least one electrical coupling member comprises at least one impedance element.
Preferably, the speed sensor and the at least two electrical connection elements exhibit a first value of the total equivalent resistance in an operating condition, when the speed sensor and the at least two electrical connection elements operate properly, or a second value of the total equivalent resistance in a failure operating condition, when the speed sensor or at least one of the at least two electrical connection elements is subjected to a malfunction, the first value of the total equivalent resistance being lower than the second value of the total equivalent resistance, and wherein the impedance element of the coupling member exhibits a resistance that is higher than the first value of the total equivalent resistance of the speed sensor and the at least two electrical connection elements and is lower than the second value of the total equivalent resistance of the speed sensor and the at least two electrical connection elements.
In an advantageous embodiment of the invention, the control unit is electrically connected to an output node of the failure-check apparatus for receiving the electrical signal, the failure-check apparatus comprising at least one resistive element forming at least part of a voltage divider, said voltage divider being adapted to provide the electrical signal at the output node to be received by the control unit.
More preferably, the voltage divider further comprises the electrical coupling member, and/or at least one further resistive element.
In an advantageous embodiment of the invention, the at least one resistive element comprises a first resistive element connected to either one of said two electrical connection elements, a second resistive element connected with the first resistive element at the output node and connected to a reference terminal for receiving a reference voltage.
Preferably, the failure-check apparatus further comprises a first diode element connected between the common node and the reference terminal, and a second diode element connected between a supply terminal for receiving a supply voltage and the output node, the first diode and second diode elements being adapted to clamp a voltage below an upper value and above a lower value, respectively.
More preferably, the failure-check apparatus further comprises at least one capacitive element connected between the output node and the reference terminal, the capacitive element and the at least one resistive element forming a low-pass filter configured to cut off high-frequency electrical signals.
In an advantageous embodiment of the invention, the control unit is configured to receive the electrical signal from the failure-check apparatus when the motor is not actuated.
Preferably, the laundry machine further comprises a control panel adapted to allow a user to select at least one laundry treating cycle, and wherein the control unit is configured to receive the electrical signal from the failure-check apparatus at a power on of the control unit before actuating the motor, and/or the control unit is configured to receive the electrical signal from the failure-check apparatus before performing the selected at least one laundry treating cycle, and/or the control unit is configured to receive the electrical signal from the failure-check apparatus before any actuation of the motor during the execution of the selected at least one laundry treating cycle.
In an advantageous embodiment of the invention, the laundry machine further comprises a switching element connected between either one of said two electrical connection elements and the failure-check apparatus, said switching element being operable by the control unit to selectively electrically connect either one of said two electrical connection elements and the failure-check apparatus.
Preferably, the control unit is configured to provide a closing signal at a closing value for closing the switching element only when the motor is not actuated, and to provide the closing signal at an opening value for opening the switching element before actuating the motor.
More preferably, the laundry machine further comprises a control panel adapted to allow a user to select at least one laundry treating cycle, and wherein the control unit is configured to provide the closing signal for closing the switching element at a power-on of the control unit, and/or the control unit is configured to provide the closing signal for closing the switching element before performing the selected at least one laundry treating cycle, and/or the control unit is configured to provide the closing signal for closing the switching element before any actuation of the motor during the execution of the selected at least one laundry treating cycle.
In an advantageous embodiment of the invention, the control unit is configured to prevent the drum rotation once the electrical signal at the second value is received.
Preferably, the control unit is configured to actuate an alarm element once the electrical signal at the second value is received.
These and others features and advantages of the solution according to the present invention will be better understood by reading the following detailed description of some embodiments thereof, provided merely by way of exemplary and non-limitative examples, to be read in conjunction with the attached drawings, wherein:

Figure 1A is an isometric view of a laundry machine in which the present invention may be implemented;
Figure 1B is a schematic cross-sectional view of the laundry machine of Figure 1A ;
Figure 2 is a schematic diagram of laundry machine circuitry comprised in the laundry machine of Figure 1 ; and
Figure 3 - 6 are schematic diagrams of a portion of the control system designed for controlling a motor of the laundry machine in which different embodiments of the present invention are implemented.

With reference to the drawings, Figures 1A and 1B are isometric and cross-sectional views, respectively, of a laundry machine 100 in which the present invention may be implemented.
The laundry machine 100 is a machine for treating laundry (such has a laundry washing machine, a laundry washing/drying machine, and possibly a laundry drying machine, etc.) of the front-loading type. Anyway, it should be apparent from the following description that laundry machines of the top-loading type may also benefit from the solution according to the present invention.
In the example at issue, the laundry machine 100 comprises a casing or cabinet 105 preferably substantially parallelepiped-shaped, which encloses a washing tub, or simply tub, 107 (as shown in Figure 1B ) preferably substantially cylindrically-shaped, wherein the laundry is treated, along with any other component of the laundry machine 100 necessary for its operation (e.g., hydraulic, electronic and electromechanical apparatuses as described in the following).
The tub 107 houses a rotatable drum 110 preferably substantially cylindrically shaped, which, in operation, rotates about an axis A in order to tumble the laundry to be washed. Typically, the tub 107 comprises, in a backside or backwall 107a thereof, a shaft opening 107b, in which a drum rotor shaft 110a is inserted. The rotor shaft 110a is attached to the drum 110 and rotatably connected by means of a transmission apparatus 115 to a drum motor 120, preferably electric, comprised in the laundry machine 100 in order to rotate the drum 110 during operation. The drum motor 120 is preferably, although not limitatively, positioned in a bottom position with respect to the casing 105. The transmission apparatus 115 may comprise a transmission belt or chain 115a coupled with a pair of pulleys 115b and 115c, of which a first pulley 115b is mounted to the drum rotor shaft 110a while a second pulley 115c is mounted to a motor shaft 120a. Alternatively, in other embodiments according to the present invention (not shown in the Figures), the rotating movement may be transferred to the drum in any known manner; for example, a motor may be directly connected to the drum (so called "direct drive"), with the motor shaft coinciding to the drum shaft.
In order to allow a user to access the tub 107 and the inside of the drum 110 (for loading/unloading the laundry), a loading/unloading opening 125 is advantageously provided on a front side of the laundry machine 100. The tub 107 is provided with a tub opening 107c, and the drum 110 is provided with a drum opening 110b. The tub opening 107c is adapted to be aligned with the loading/unloading opening 125 provided in the casing 105, and with the drum opening 110b of the drum 110.
Preferably, in order to achieve a watertight connection between the loading/unloading opening 125 and the tub opening 107b (in order to avoid leakages of washing liquid into the casing 105), a bellows 130, preferably made of an elastomeric and waterproof material, is mounted in a watertight manner (such as by gluing, by welding, by interference fitting, etc.) to both a border of the tub opening 107c and a border of the loading/unloading opening 125.
The loading/unloading opening 125 is closable by a door 135, which is hinged, preferably, to the casing 105 by means of a hinge (not shown in the figures).
The tub 107 is fluidly connected with a hydraulic apparatus (not shown in the drawings) adapted to provide washing liquids (e.g., water mixed with detergents) in the washing tub 107 for treating the laundry therein, and to exhaust such liquids once used. The laundry machine 100 may possibly comprise also a drying air apparatus (not shown) fluidly connected with the tub 107 adapted to heat up and blow drying air into the tub and draw therefrom moisturized cool air.
In addition, preferably, although not limitatively, on a top portion 105t of the casing 105 a user interface 140 is provided. Preferably, although not limitatively, the user interface 140 may comprise a control panel 140a for selecting laundry treatment cycles (e.g., a set of operations and parameters designed for treating peculiar fabrics, such as wool items) to be carried out by the laundry machine 100, and a drawer 140b for loading laundry-treating products (e.g., detergents, softeners, bleachers, etc.).
The laundry machine 100 is advantageously provided with a control unit 150 (e.g., comprising one or more microcontroller and/or other electronic devices) adapted to control the laundry machine 100 operation (as discussed in the following), which is preferably, although not necessarily, placed in a top position inside the casing in order to be less prone to contacts with liquids or humidity possibly leaking from the tub 107.
Turning now to Figure 2 , there is shown a schematic diagram of a laundry machine circuitry 200 comprised in the laundry machine 100.
It should be readily understood that the term laundry machine circuitry 200 is herein meant to denote generally the electric, electromechanical and electronic components provided in the laundry machine 100. In other words, the laundry machine circuitry 200 comprises elements of the laundry machine 100 that (both directly or indirectly) require electric energy for their operation.
Preferably, the laundry machine 100 is connected to the Mains through an electric cable element (not shown), such as an electric cord, which provides electric energy to the laundry machine circuitry 200. For example, the laundry machine 100 receives the line power signal at a line node L of the laundry machine circuitry 200, while at a node N the neutral power signal is provided.
A voltage converter, such as a SMPS (Switching Mode Power Supply), 205 is connected to both line node L and neutral node N, thus receiving the electric energy from the Mains - usually provided with a 230V or 125V alternating voltage at a frequency of 50Hz or 60Hz, respectively. The SMPS 205 is connected to a control system 210, feeding thereto one or more regulated supply voltages (e.g., 3V, 5V and 12V DC supply voltages with respect to a reference voltage at 0V also supplied by the SMPS 205), for example adapted to be supplied to electronic devices (such as microcontroller, sensor, memory devices, etc.) comprised in the control system 210. The control system 210 comprises one or more sensor elements (not shown in the figure), each of which adapted to acquire part of an input information I related with the operation of one or more respective electric/electromechanical elements - denoted with 215 as a whole - provided in the laundry machine 100 for the operation thereof (e.g., in order to perform the selected laundry treating cycle), which is controlled by output control signals O (as described in the following). In addition, the control system 210 is advantageously adapted to receive a further part of the input information I set through the control panel 140a by a user (such as a selected laundry treating cycle).
The one or more electric/electromechanical elements 215 are, preferably, selectively connected to the line node L and the neutral node N by means of at least one respective switching element of a set 217 of switching elements (such as transistors, triacs, relays, etc.), controlled by the control system 210 (as described in the following). In the example at issue, the one or more electric/electromechanical elements 215 of the laundry machine 100 advantageously comprises, in a nonlimiting way, a drain pump 225 in series with a pump switching element 225a, a washing heater 230 in series with a washing switching element 230a, a drying apparatus 235 (e.g., an air heater element, a blower, etc.) in series with a drying apparatus switching element 235a, a recirculation/drying apparatus actuator 240 (e.g., adapted to actuate a recirculation pump and/or a blower fan) in series with an actuator switching element 240a, the drum motor 120 in series with a drum motor switching element 220a and a plurality of valves (e.g., adapted to hydraulically interconnect treating-product reservoirs and water inlet pipe), such as a wash valve 245, a pre-wash valve 250 and a bleach valve 255 each in series with a respective valve switching element 245a, 250a e 255a.
Preferably, a door switch 260 is provided between the line node L and part of the electric/electromechanical elements 215. For example, the door 135 may comprise mechanical, electromechanical or magnetic elements adapted to close the door switch 260 only when the door 135 is in the closed position. This is a security measure, which prevents the electric/electromechanical elements 215 downstream the door switch 260 from being operated while the door 135 is open; in this way, annoying and/or potentially harmful accident (e.g., liquids leakages and/or laundry items ejection caused by valves 245, 250 and 255 opening and/or drum 110 rotating, respectively, while the door 135 is open) are avoided.
In addition, each of the electric/electromechanical elements 215 comprising rotating parts (such as the motor 120 and/or recirculation/drying apparatus actuator 240 in the example at issue) may be selectively connected in opposite configurations to the line node L and to the neutral node N by means of relay elements (such relay elements are omitted in Figure 2 for the sake of simplicity since they are well known) to be rotated in different directions (as described in the following). Such relay elements are coupled in series between the line nodes L and N and the electric/electromechanical elements 215 comprising rotating parts, and are also connected to the control unit 150 (for receiving one of the output control signals O that select the configuration, as described in the following).
During operation, the control system 210 is adapted to output one or more output control signals O, which are generally, but not limitatively, used for controlling the operation of the laundry machine 100. For example, the control system 210 ensures a selected laundry treating cycle (e.g., a wool items treating cycle) to be performed by the laundry machine. The control system 210 advantageously operates one or more switching element of the set 217 according to an acquired part of the input information I and/or associated operating instructions (e.g., sequences of activation of one or more electric/electromechanical elements 215 and/or predetermined operating time periods thereof) stored in a memory device (not shown) comprised in the control system 210. Each sensor element converts a respective part of the acquired input information I (such as washing liquid/drying air temperatures, revolution per minutes of the motor 120, etc.) in a corresponding electrical signal provided to the control unit 150 (shown in Figure 3 ) comprised in the control system 210 (as discussed in the following).
In other embodiments of the present invention (not shown in the drawings), the control of the supplying of electric energy to the electric/electromechanical elements 215 may be automatically performed by the control system 210, for example, by automatically implementing an instructions set stored in the memory device of the control system 210 (e.g., the laundry machine 100 may be adapted to automatically perform a predetermined laundry treating cycle).
Considering now Figure 3 , it is a schematic diagram of a portion 300 of the control system 210 designed for controlling the operation of the drum motor 120 of the laundry machine 100 in which an embodiment of the present invention is implemented.
The control system 210 comprises a (angular) speed sensor, such as a tachometer dynamo 310, preferably coupled with the motor shaft 120a of the motor 120. A pair of electrical connection elements, such as a couple of wires 317a and 317b connects the tachometer dynamo 310 with the control unit 150.
The control unit 150 comprises a conditioning circuit 315 and a controller 319. The conditioning circuit 315 receives the first wire 317a of the couple at a first input In₁ (e.g., a connector element provided on an electronic board, not shown, onto which component parts of the control unit 150 are mounted), and the second wire 317b at a second input In₂ (e.g., another connector element). Such wires 317a and 317b may have a length in the order of the meter since the motor 120 is positioned in a substantially opposite location with respect to the control unit 150 inside the casing 105, as can be appreciated in Figure 1 b. Moreover, the conditioning circuit 315 receives (e.g., from the SMPS 205) a first supply voltage V_SMPS1 (e.g., 5V) at a first supply terminal V_s+, and a reference voltage V_GND (e.g., 0V) at a second supply terminal V_s-. An output terminal O_s of the conditioning circuit 315 is connected with a motor input terminal In_M of the controller 319 mentioned above.
The controller 319 receives a second supply voltage V_SMPS2 (e.g., 5V) at a first supply terminal V_c+, and the reference voltage V_GND at a second supply terminal V_c-, both provided by the SMPS 205. The controller 319 is connected, by means of an output terminal O_M, to a control terminal of the drum motor switching element, a triac 220a in the example at issue, coupled to the drum motor 120. In order to allow the motor 120 being rotated in different directions (in order to rotate the drum 110 in different directions too), relay elements 321a and 321b are coupled with the drum motor 120. Such relay elements 321a and 321b are controlled by the controller 319 (in the figure connections between the relay elements 321a and 321b and the controller are omitted for the sake of simplicity) in order to selectively connect the motor 120 in two opposite configurations with the line node L and the neutral node N (as well known in the art). For example, a first configuration causes the motor 120 (and the drum 110) to rotate in clockwise direction (e.g., with the relay elements 321a and 321b connecting the line node L and neutral node N to the motor 120 in a first manner), while a second configuration cause the same to rotate in counterclockwise direction (e.g., with the relay elements 321a and 321a connecting the line node L and neutral node N in a second manner complementary to the first manner).
According to one embodiment of the present invention the control system 210 further comprises at least one impedance element, such as a resistor, implemented as an electrical coupling member 325, connected between the first wire 317a and the second wire 317b. Advantageously, the electrical coupling member 325 may be provided in proximity of the conditioning circuit 315; for example the coupling member 325 may be positioned near to the connection between the conditioning circuit 315 and the wires 317a and 317b, preferably, although not limitatively, between the inputs In₁ and In₂ of the conditioning circuit 315 (e.g., between the connectors on the electronic board mentioned above). Nevertheless, in other embodiments according to the present invention (not shown in the drawings), the electrical coupling member 325 may comprise one or more impedance elements other than a resistor. In some embodiments, the resistor may be replaced by another suitable impedance element (e.g., comprising inductors and capacitors) adapted to exhibits an impedance comprising a desired resistive value on a selected range of operative frequencies (e.g., a range of frequencies comprising the frequencies corresponding to angular speed of the motor 120 properly working). In other embodiments, an active element may be used as coupling member 325. For example, a MOS transistor may be connected between the first wire 317a and the second wire 317b by means of conduction terminals thereof; whereas, a control gate of the MOS transistor may be biased (e.g., by the controller 319) for operating in triode region (i. e., with a desired resistive value).
During (normal) operating condition (i.e., when the portion 300 of the control system 210 works properly), the tachometer dynamo 310 provides an oscillating voltage V_T that oscillates at a frequency proportional to the number of revolution per minutes (rpm) performed by the motor shaft 120a, and, for example having a maximum amplitude comprised between 50V and 100V. The conditioning circuit 315 is adapted to convert such oscillating voltage V_T into a conditioned signal adapted to be processed by the controller 319. For example, the conditioning circuit 315 may be adapted to convert the oscillating voltage V_T into a (conditioned) square-wave signal V_Sq switching between the first supply voltage V_SMPS1 and the reference voltage V_GND at a frequency proportional to (e.g., equal to) the oscillating voltage V_T.
The controller 319 provides a motor control signal to the triac 220a through the motor output terminal O_M based on such conditioned signal. In detail, the controller 319 analyses the conditioned signal and determines if an actual rotating speed of the motor shaft 120a (and therefore of the drum 110) corresponds to a target rotating speed (e.g., defined by the operating instructions) or if the actual rotating speed has to be increased up or slowed down for catching such target rotating speed. Therefore, the controller 319 provides the motor control signal to the triac 220a, which is alternatively opened and closed by the motor control signal in such a way to feed a required average amount of electric energy to the motor 120 for rotating the motor shaft 120a (and therefore of the drum 110) at the target rotating speed. For example, during each half-period of the alternating voltage from the Mains, in order to increase the rotating speed of the motor shaft 120a the triac 220a is closed for a time interval longer than a complementary time interval in which is open; vice-versa, in order to slow down the rotating speed of the motor shaft 120a the triac 220a is closed for a time interval shorter than a complementary time interval in which is open.
In (normal) operating condition, the electrical coupling member 325 is preferably designed in order not to have any influence on the portion 300 of the control system 210, which is controlling the drum motor 120 operation. This can be achieved by designing the resistance R_D of the electrical coupling member 325 to be much greater than an equivalent resistance R_T exhibited by the tachometer dynamo 310 (at the coupling member 325 terminals) and than an equivalent resistance R_W exhibited by the wires 317a and 317b (at the coupling member 325 terminals) when properly working; in this way, any electric current crossing the electrical coupling member 325 will be of a negligible amount. In other words, the resistance R_D of the electrical coupling member 325 has to be grater than a total equivalent resistance R_tot exhibited by the wires 317a and 317b and the tachometer dynamo 310 as can be detected at connecting terminals of the coupling member 325 (i.e., which connects the coupling member 325 to the wires 317a and 317b). For example, the total equivalent resistance R_tot (during the operating condition) comprises the equivalent resistance R_T of the tachometer dynamo 310, which is usually comprised between 50-100Ω (although other resistance values are possible), and an equivalent resistance R_W of each wire 317a and 317b, which is usually in the order of few to tenths of Ohms (although other resistance values are possible); thus by designing the resistance R_D of the electrical coupling member 325 equal, or greater than, 10KΩ, any electric current flowing through the electrical coupling member 325 will have an intensity substantially equal to, or lower than, the approximately 0,5-1% of an intensity of a current flowing through the wires 317a and 317b and the tachometer dynamo 310 (i.e., a negligible intensity).
Conversely, a failure condition occurs when a malfunction of the tachometer dynamo 310 (e.g., one or more component parts thereof break down or disconnect, thus impeding the tachometer dynamo 310 from properly working), and/or of at least one of the first wire 317a and the second wire 317b (e.g., breaking or detaching from the tachometer dynamo 310 due to excessive operating oscillations) opens the connection between the tachometer dynamo 310 and the conditioning circuit 315. Therefore, the total equivalent resistance R_tot exhibited by the tachometer dynamo 310 and by the wires 317a and 317b rises up to an ideally infinite value. In other words, the failure condition occurs whenever the electrical link between the inputs In₁ and In₂ provided by the tachometer dynamo 310 wires 317a and 317b (without considering the coupling member 325) opens, which brings the total equivalent resistance R_tot to an open circuit value (i.e., ideally infinite). In such a scenario, the electrical coupling member 325 (which resistance R_D now results much lower than the total equivalent resistance R_tot ) maintains connected together the first wire 317a and the second wire 317b. The electrical coupling of the electrical coupling member 325 with the first wire 317a and the second wire 317b exhibits an overall low impedance (substantially equal to the resistance R_D itself) compared to the actual total equivalent resistance R_tot. It follows that, thanks to the electrical coupling member 325, the wires 317a and 317b are prevented from acting as an antenna; in other words, the wires 317a and 317b are prevented from receiving variable electromagnetic fields (e.g., produced by the alternating voltage supplied from the Mains) and from generating spurious electrical signals from electrical energy absorbed from such variable electromagnetic fields thanks to the electrical coupling member 325 interconnecting the first wire 317a with the second wire 317b. It should be noted that by positioning the electrical coupling member 325 close to (or at) the conditioning circuit 315 inputs In₁, and In₂ a good robustness against mechanical stresses mentioned above thereof is achieved as well as a protection from failure conditions (e.g., at least a wire 317a,317b breaks down) of the wires 317a and 317b that may occur at any length thereof is ensured.
In such a failure condition, thanks to the coupling member 325 the conditioning circuit 315 provides a constant electrical signal (e.g., a 5V voltage at 0Hz) to the motor input terminal In_M of the controller 319, which is not interpreted as a fake speed indication (i.e., an oscillating spurious electrical signal). Advantageously, the controller 319 may be configured to identify a failure condition if the constant electrical signal is received at the motor input terminal In_M whenever a not-null speed is expected according to the selected treating cycle. For example, the controller 319 may identify the failure condition whenever is received the constant electrical signal (instead of an oscillating electrical signal) while the controller 319 is driving the triac 220a for actuating the motor 120.
Preferably, once a failure condition is identified, the controller 319 may be configured for taking countermeasures to prevent damages to the laundry being treated, the laundry machine 100 and/or the environment where the laundry machine 100 is placed. For example, the controller 319 may be configured to set the triac 220a in an open condition (i.e., disabling the drum motor 120), to activate an alarm (e.g., by activating an optical and/or acoustical alarm element provided in the control panel 140a) and/or to complete the selected treating cycle in a safe mode (e.g., concluding the treating cycle without rotating the drum 110).
Preferably, although not limitatively, the controller 319 may be configured to prevent any further activation of the drum motor 120 after a failure condition is identified. A reset or ON/OFF element (e.g., a pushbutton not shown in the drawings) may be further provided in the control panel 140a or in the control system 210 in order to enable the operation of the drum motor 120 again, once the origin of the failure has been overcome (e.g., broken tachometer dynamo 310 and/or wires 317a and 317b are repaired or replaced).
Therefore, the laundry machine 100 according to an embodiment of the present invention is able to safely avoid drawbacks due to electromagnetic fields - permeating the environment where the laundry machine 100 is placed, and therefore the laundry machine 100 itself - an energy of which may be converted by the wires 317a and 317b in (oscillating) spurious electrical signals.
Considering now Figure 4 , it is a schematic diagram of an alternative portion 400 of the control system 210 designed for controlling the operation of the drum motor 120 of the laundry machine 100 in which an another embodiment of the present invention is implemented.
The portion 400 of the control system 210 differs from the portion 300 previously described in the following.
The portion 400 of the control system 210 according to one embodiment of the present invention comprises a failure-check apparatus 430, which is connected to one between the wires 317a and 317b and to a failure input terminal In_F of the controller 319, and adapted to identify a failure condition. For example, the failure-check apparatus 430 may be coupled to one of the wires 317a and 317b in proximity to the connection between the conditioning circuit 315 and the wires 317a and 317b; preferably, although not limitatively, the failure-check apparatus 430 may be connected to one of the inputs In₁ and In₂ of the conditioning circuit 315 (e.g., to one of the connectors on the electronic board mentioned above), obtaining the similar advantages to those mentioned above with respect to the coupling member 325.
In the example at issue, the failure-check apparatus 430 comprises a first resistor 435, a second resistor 440, a capacitor 445 and, preferably, but not limitatively, a pair of diode elements 450a and 450b (e.g., a pair of normal p-n junction diodes, Schottky diodes, Zener diodes, etc.). The first resistor 435 is connected between the second wire 317b and a output node X of the failure-check apparatus 430, while the second resistor 440, the capacitor 445 and the (first) diode element 450a are connected between the output node X and a reference terminal at the reference voltage V_GND. The (second) diode element 450b is instead connected between the output node X and a supply terminal for receiving a third supply voltage V_SMPS3 (e.g., 12V or 5V supplied by the SMPS 205). The output node X is connected to the failure input In_F of the controller 319. Advantageously, the resistors 435, 440 and the electrical coupling member 325 and the capacitor 445 provide a low-pass filter adapted to suppress (attenuating) any oscillating signals from the tachometer dynamo 310.
It should be clear that the structure of the failure-check apparatus 430 described above is merely an illustrative embodiment which may subjected to several changes without departing from the scope of the present invention; particularly, other embodiments of the present invention are possible featuring a different number of resistors (i.e., just one resistor or more than two resistors).
The controller 319 is advantageously adapted to verify if the failure condition occurs at predetermined time instants of the operation of the laundry machine 100. Advantageously, the controller 319 may be configured for sensing the voltage signal received at the failure input In_F during a startup phase of the laundry machine 100, which is started by the power on of the laundry machine (e.g., by means of a power-on button provided in the control panel 140a). Alternatively or in addition, the controller 319 may be configured for sensing the voltage signal received at the failure input In_F just before starting a selected laundry treating cycle (e.g., selected by a user through the control panel 140a). As a further alternative or addition, the controller 319 may be configured for sensing the voltage signal received at the failure input In_F during each selected laundry treating cycle before any actuation of the drum motor 120. Generally, the controller 319 is preferably configured for sensing the voltage signal received at the failure input In_F at any time the rotation of the motor 120 is stopped, in order to substantially avoid any drawbacks mentioned above at any point of the operation of the laundry machine 100.
During operation under normal condition, only a negligible electric current - drained from the conditioning circuit 315 through the coupling member 325 - flows through the first resistor 435 towards the second resistor 440 (since any electric current is almost entirely absorbed by the tachometer dynamo 310 thanks to the low total equivalent resistance R_tot as previously described). The output node X is brought to a normal voltage value V_XW (which is provided to the failure input terminal In_F of the controller 319) substantially equal to the second supply voltage V_SMPS2 (provided by the conditioning circuit 315). The controller 319 is configured to identify the normal voltage value V_XW as an indication of a normal working condition (e.g., by means of a comparator element, not shown); therefore, the operation of the laundry machine 100 proceeds by implementing the selected treating cycle
Advantageously, the pair of (optional) diode elements 450a and 450b are adapted to clamp voltage oscillations from the tachometer dynamo 310 exceeding a voltage operating range defined by the on voltage V_D of diode elements 450a and 450b and the voltage V_SMPS3 supplied by the SMPS 205 (e.g., voltages higher than V_SMPS3 +V_D and voltages lower than - V_D ) that could harm the controller 319.
Conversely, when a failure condition occurs (e.g., at least one between the wires 317a or 317b, or the tachometer dynamo 310 fails), the electric current flowing through the first resistor 435 towards the second resistor 440 rapidly increases (since the total equivalent resistance R_tot rises, as previously discussed), and the output node X is brought to a failure voltage value V_XF equal to the portion of the second supply voltage V_SMPS2 across the second resistor 440. In other words, the failure voltage value V_XF at output node X is determined by a voltage divider comprising the coupling member 325, the first resistor 435 and the second resistor 440, or: $V_{XF} = V_{SMPS 2} \cdot \frac{R_{F 2}}{R_{F 2} + R_{F 1} + R_{D}},$
where R_F1 is the resistance of the first resistor 435, and R_F2 is the resistance of the second resistor 440.
When at the failure input terminal In_F senses a voltage at the failure value V_XF, the failure condition is detected. Therefore, countermeasure(s) may be taken; for example, preventing the laundry machine operation 100 and/or activating an alarm (e.g., provided in the control panel 140a).
Thanks to the failure condition control performed during the startup phase of the laundry machine 100 by the failure-check apparatus 430 according to an embodiment of the present invention, it is possible to prevent any uncontrolled actuation of the drum motor 120 and of the rotation of the drum 110, nullifying (or at least minimizing) any harmful drawbacks mentioned above.
It should be readily understood that, in a further embodiment according to the present invention, the failure-check apparatus 430 may be connected to the first wire 317a instead to the second wire 317b as well. In such case (not shown) the voltage divider, now comprising the resistors 435 and 440 which resistances should be modified for providing again the failure voltage value V_XF at a value suitable to be received by the controller 319.
Moreover, in yet another further embodiment according to the present invention, the coupling element 325 may be omitted, with the failure-check apparatus 430 that alone allow the control circuit 150 to prevent the actuation of the drum 110 during a failure condition of the speed sensor 310 and/or of the wires 317a and 317b.
It should also be appreciated that an alternative failure-check apparatus 430 could be designed for providing a different electrical quantity other than a voltage in order to identify the failure conditions. For example, an alternative failure-check apparatus (not shown) may be implemented for providing a predetermined electric current value to the controller 319 when a failure conditions is identified.
Turning now to Figure 5 , it is a schematic diagram of an alternative portion 500 of the control system 210 designed for controlling the operation of the drum motor 120 of the laundry machine 100 in which a further embodiment of the present invention is implemented.
The portion 500 of the control system 210 differs from the portion 400 previously described in the following.
The failure-check apparatus 430 is preferably, although not limitatively, selectively connected to the second wire 317b by means of a failure-check switching element 555 (e.g., a transistor), which may advantageously be connected to a failure output terminal OF of the controller 319 through a respective control terminal to be operated by the controller 319.
At the predetermined time instants (e.g., at power on of the control unit 150, before a predetermined laundry treating cycle, and/or before any activation of the drum motor 120 as previously described), the failure-check apparatus 430 is connected to the electrical coupling member 325 by providing a closing signal at a closure value (e.g., a constant voltage at 5V) to the control terminal of the failure-check switching element 555, which closes. Then the voltage value received at the failure input terminal In_F is sensed as previously discussed. Once the failure check is performed, the failure output terminal OF provides the closing signal at an opening value (e.g., a constant voltage at 0V) to the failure-check switching element 555, which opens, thus disconnecting the failure-check apparatus 430 from the second wire 317b and the electrical coupling member 325.
Subsequently, the operation of the laundry machine 100 may be prevented and other countermeasure(s) such as the ones mentioned above may be performed, or the operation of the laundry machine 100 may normally start according to whether a failure condition has been detected or as not been detected, respectively.
During the operation under normal condition, the controller 319 maintains the failure-check switching element 555 in an open condition by providing the closing signal at the opening value to the control terminal of the failure-check switching element 555 through the fail-check output terminal OF. Under this condition, the failure-check apparatus 430 is disconnected from the considered part of the control system 210, neither substantially consuming electric energy nor providing any signal to the fail-check input port In_F.
It should be understood that a further failure-check apparatus (not shown) may be implemented, in which the failure-check switching element 555 could be directly connected to the wire 317a (in such case changes to the resistor may be required as previously discussed).
Also in this case, a further embodiment (not shown) according to the present invention may be provided in which the coupling element 325 is omitted.
Finally, it should be promptly understood that thanks to the solution according to the present invention it is also possible to prevent the driving of the motor 120 also in the case the latter incurs in a malfunction that prevents the same from rotating; thus avoiding the drawbacks caused by a motor 120 failure, such as overheating or sparks produced by malfunctioning of the (according to the type of electric motor implied) rotor or stator windings, and/or electrical brushes thereof.

Claims

A laundry machine (100) for treating laundry items comprising a drum (110) adapted to house the laundry to be treated, a motor (120) arranged for rotating the drum, a control system (210) adapted to adjust the operation of the laundry machine at least partially based on acquired operating information,
said control system (210) comprising at least one speed sensor (310) adapted to provide an electrical signal containing information on a rotating speed of the motor (120), at least two electrical connection elements (317a, 317b) adapted to electrically connect the speed sensor (310) to a control unit (150) for transferring the electrical signal from the speed sensor (310) to the control unit (150), said control unit (150) being operable to receive said electrical signal and adjust the rotating speed of the motor (120) accordingly,
characterized in that
the control system (210) further comprises at least one electrical coupling member (325) adapted to electrically interconnect said two electrical connection elements (317a, 317b) for preventing said two electrical connection elements (317a, 317b) from acting as a receiver of electromagnetic fields permeating the laundry machine (100), and/or
a failure-check apparatus (430) connected to either one of said two electrical connection elements (317a, 317b), the failure-check apparatus (430) being adapted to provide to the control unit (150) an electrical signal identifying a failure condition in which at least one of said two electrical connection elements (317a, 317b) and/or the speed sensor (310) is subjected to a malfunction.
The laundry machine (100) according to claim 1, wherein the at least one electrical coupling member (325) comprises at least one impedance element.
The laundry machine (100) according to claim 1 or 2, wherein the speed sensor (310) and the at least two electrical connection elements (317a, 317b) exhibit a first value of the total equivalent resistance in an operating condition, when the speed sensor (310) and the at least two electrical connection elements (317a, 317b) operate properly, or a second value of the total equivalent resistance in a failure operating condition, when the speed sensor (310) or at least one of the at least two electrical connection elements (317a, 317b) is subjected to a malfunction, the first value of the total equivalent resistance being lower than the second value of the total equivalent resistance, and wherein the impedance element of the coupling member (325) exhibits a resistance that is higher than the first value of the total equivalent resistance of the speed sensor (310) and the at least two electrical connection elements (317a, 317b) and is lower than the second value of the total equivalent resistance of the speed sensor (310) and the at least two electrical connection elements (317a, 317b).
The laundry machine (100) according to any one of the preceding claims 1 to 3, wherein the control unit (150) is electrically connected to an output node (X) of the failure-check apparatus (430) for receiving the electrical signal, the failure-check apparatus (430) comprising at least one resistive element (435, 440) forming at least part of a voltage divider, said voltage divider being adapted to provide the electrical signal at the output node (X) to be received by the control unit (150) .
The laundry machine (100) according to claim 4, wherein the voltage divider further comprises the electrical coupling member (325), and/or at least one further resistive element (435, 440).
The laundry machine (100) according to claim 4 or 5, wherein the at least one resistive element (435, 440) comprises a first resistive element (435) connected to either one of said two electrical connection elements (317a, 317b), a second resistive element (440) connected with the first resistive element (435) at the output node (X) and connected to a reference terminal for receiving a reference voltage.
The laundry machine (100) according to any one of the preceding claims 1 to 6, wherein the failure-check apparatus (430) further comprises a first diode element (450a) connected between the common node and the reference terminal, and a second diode element (450b) connected between a supply terminal for receiving a supply voltage and the output node, the first diode (450a) and second diode (450b) elements being adapted to clamp a voltage below an upper value and above a lower value, respectively.
The laundry machine (100) according to any one of the preceding claims 4 to 7, wherein the failure-check apparatus (430) further comprises at least one capacitive element (445) connected between the output node (X) and the reference terminal, the capacitive element (445) and the at least one resistive element (435, 440) forming a low-pass filter configured to cut off high-frequency electrical signals.
The laundry machine (100) according to any one of the preceding claims 1 to 8, wherein the control unit (150) is configured to receive the electrical signal from the failure-check apparatus (430) when the motor is not actuated.
The laundry machine (100) according to any one of the preceding claims 1 to 9, wherein the laundry machine further comprises a control panel (140a) adapted to allow a user to select at least one laundry treating cycle, and
wherein the control unit (150) is configured to receive the electrical signal from the failure-check apparatus (430) at a power on of the control unit (150) before actuating the motor (120), and/or
the control unit (150) is configured to receive the electrical signal from the failure-check apparatus (430) before performing the selected at least one laundry treating cycle, and/or
the control unit (150) is configured to receive the electrical signal from the failure-check apparatus (430) before any actuation of the motor (120) during the execution of the selected at least one laundry treating cycle.
The laundry machine (100) according to any one of the preceding claims 1 to 10, further comprising a switching element (555) connected between either one of said two electrical connection elements (317a, 317b) and the failure-check apparatus (430), said switching element (555) being operable by the control unit (150) to selectively electrically connect either one of said two electrical connection elements (317a, 317b) and the failure-check apparatus (430).
The laundry machine (100) according to claim 11, wherein the control unit (150) is configured to provide a closing signal at a closing value for closing the switching element (555) only when the motor (120) is not actuated, and to provide the closing signal at an opening value for opening the switching element (555) before actuating the motor (120).
The laundry machine (100) according to claim 11 or 12, further comprising a control panel (140a) adapted to allow a user to select at least one laundry treating cycle, and
wherein the control unit (150) is configured to provide the closing signal for closing the switching element (555) at a power-on of the control unit (150), and/or
the control unit (150) is configured to provide the closing signal for closing the switching element (555) before performing the selected at least one laundry treating cycle, and/or
the control (150) unit is configured to provide the closing signal for closing the switching element (555) before any actuation of the motor (120) during the execution of the selected at least one laundry treating cycle.
The laundry machine (100) according to any of the preceding claims 4 to 13, wherein the control unit (150) is configured to prevent the drum (110) rotation once the electrical signal at the second value is received.
The laundry machine (100) according to any of the preceding claims 4 to 14, wherein the control unit (150) is configured to actuate an alarm element once the electrical signal at the second value is received.