Electronically controlled backflow prevention

Abstract

A system for preventing backflow from a household appliance is provided. In some embodiments, the system includes a flow meter (603) for measuring a water flow and a control circuit (606, 607), where the flow meter (603) includes a quadrature encoder that provides a dual channel signal. The control circuit is configured to determine a flow direction based on the first signal of the first channel and the second signal of the second channel, and to provide a control signal for the valve (602) based on the determined flow direction. Associated methods and assemblies are also provided.

Description

Technical Field

[0001] This application relates to an electronic control system for preventing water backflow from household appliances, particularly for controlling valves of household appliances to prevent water from flowing back from the inlet of the household appliances into the domestic water supply system. Background Technology

[0002] Household appliances with fixed water supply connections (such as washing machines and dishwashers) are connected to the water supply network. In such systems, backflow from the appliances to the water supply network must be prevented. In particular, backflow from the appliances to the water supply network can occur when pressure drops in the network. Backflow, especially from grey water lines, must be avoided to prevent contamination of the water supply system.

[0003] New regulations may require additional check valves to prevent backflow from household appliances into the water supply system. However, these additional check valves are expensive and include moving parts within the water flow path that could clog the water supply or cause leaks if they malfunction or break down.

[0004] Therefore, a simple and inexpensive solution is needed to prevent backflow from household appliances to the water supply network, preferably with no or almost no additional components in the water flow path. Summary of the Invention

[0005] This application provides an electronic solution for measuring flow rate and providing corresponding control signals to valves that disconnect household appliances from freshwater supply systems.

[0006] It is known that flow meters are provided at the inlet or downstream of household appliances to measure the inflow rate of water entering the appliances.

[0007] This application provides a system for preventing backflow from a household appliance into the local freshwater supply by electronically controlling a valve according to the direction of water flow.

[0008] According to a first aspect of the disclosed technology, a system for preventing backflow from household appliances is provided. For example, a system for preventing backflow from a dishwasher or washing machine into a local water supply system. The system includes a flow meter for measuring water flow, wherein the flow meter includes a quadrature encoder and control circuitry; the quadrature encoder provides dual-channel signals, the dual-channel signals having a first signal on a first channel and a second signal on a second channel; the control circuitry determines the flow direction based on the first signal of the first channel and the second signal of the second channel, and provides a control signal to a valve based on the determined flow direction. Each signal of each channel can preferably be generated by a corresponding sensor.

[0009] In certain configurations, the flow meter is a conventional flow meter based on a single sensor that measures the rotational speed signal, wherein the flow meter includes an additional sensor that provides a second signal, which is out of phase with the first signal. This system can be applied to commercially available appliances. For example, an existing single-channel flow meter can be reconfigured by providing the additional sensor. The control circuitry can be based on existing available electronic control platforms, such as those currently used to control dishwashers or washing machines. For example, an Aweco AMP converter can be used. The signals from the quadrature encoder (formed by two sensors providing dual-channel signals, where each signal is preferably 90° out of phase) can indicate the flow direction. For example, the sign of the phase difference between the two channels indicates whether the water flowing through the flow meter is in the forward direction (i.e., water flows out of the water supply system and into the appliance's inlet) or in the reverse direction (i.e., water flows out of the appliance's inlet and back into the local water supply system). In some configurations, a positive / negative sign can indicate forward flow, while a negative / positive sign can indicate reverse flow. Based on the determined flow direction, the system can provide control signals to valves. In some configurations, the valve can be part of the system or can be a valve upstream of the appliance's inlet, such as a stop valve. The flow meter can provide a signal that allows determination of the impeller speed. In some configurations, when the flow direction through the flow meter is reversed, the system can provide a control signal to close the valve. The control signal can alternatively be a digital signal, an analog signal, or a PWM (pulse width modulation) signal. Alternatively, the control signal can be a TTL signal, an analog voltage, or a software-implemented digital input, such as a stored variable. In some configurations, the valve can open based on a high or true signal and close upon receiving a low or false signal. In some configurations, the valve can open and close based on an analog voltage. In some configurations, the valve can open and close based on a digital voltage indicating a true or false state.

[0010] This solution allows existing flow meters to be modified to provide quadrature encoders by providing additional sensors. Therefore, the solution is versatile, easy to implement, and inexpensive.

[0011] Preferably, the quadrature encoder includes two sensors and at least one magnet, wherein the first sensor provides a first signal provided on a first channel, and the second sensor provides a second signal provided on a second channel. Thus, the flow meter can detect flow rate and direction by providing two out-of-phase signals. In the case of backflow, the valve (e.g., a stop valve) closes upon receiving a corresponding control signal from the disclosed system. Therefore, the control circuitry advantageously replaces mechanical solutions, such as check valves.

[0012] The sensor can be any sensor configured to detect a magnetic field; in particular, the sensor can be configured to detect changes in the field direction. Providing two sensors and two sensor channels that provide signals from the sensors (where the sensors are aligned with a preferred electrical phase angle of 90° relative to the measured entity) allows for the determination of movement and direction of movement. The sensor can be a Reed sensor or a Hall sensor.

[0013] Today, household appliances use flow meters, which provide a single-channel signal typically generated by a reed switch. The reed switch detects the magnetic field of a magnet rotating with the flow meter's impeller. While the rotation frequency can be determined when the magnet rotates around the impeller's axis, the direction is uncertain. For example, when the poles of a bipolar magnet rotate in a circle around the axis of rotation, the single-channel reed switch generates two pulses per revolution. However, the signal is the same for every direction of rotation.

[0014] Two magnetic sensors (e.g., Hall or Reid sensors, mounted relative to the axis of rotation and at a preferred 90° angle to each other) and a bipolar magnet (whose poles are arranged to rotate in a circle around the axis of rotation of the impeller) allow for direction detection. The phase difference between the signals indicates direction. For example, direction can be determined by comparing which signal leads another. Furthermore, double-edge detection using the rising and falling edges of one channel will produce the same resolution as the known single-channel reed switches currently used in flowmeters without direction sensing. Single-edge detection using only one edge (rising or falling edge) of one channel will provide half the resolution. Quadruple-edge detection using the rising and falling edges of two channels will produce double the resolution. Therefore, the resolution can be changed by the software used or by programming. Thus, the resolution can be adjusted, for example, the system can be configured to use quadruple-edge detection where high resolution is required.

[0015] The advantage of using a Hall sensor instead of a Reid sensor is that the sensor is smaller and easier to install.

[0016] Alternatively or additionally, the sensor used for the quadrature encoder can be a bipolar latching sensor. Advantageously, bipolar latching sensors are more robust than Hall or Reid sensors and provide more reliable detection and corresponding signals.

[0017] Alternatively or additionally, the magnetic poles of a magnet rotating around the impeller's axis of rotation of the flowmeter may generate a peak magnetic field of 100 mT at the sensor. The sensor's switching threshold can be 10 mT.

[0018] Alternatively or additionally, these two signal channels can be provided on separate signal lines that can be connected to the I / O expansion ports of commercially available electronic control circuits for household appliances. For example, the electronic control circuit can connect the two sensor signals and the stop valve using appropriate drive circuitry (e.g., relays, power transistors, triacs, etc.).

[0019] Alternatively or additionally, the control circuitry can analyze the dual-channel signal, for example, by analyzing the switching patterns of the rising and falling edges to determine the phase difference. The phase difference between the rising and falling edges, or a particular switching pattern, can correspond to a specific direction of rotation. For example, a first phase difference or switching pattern corresponds to the forward direction, and a second phase difference or switching pattern corresponds to the reverse direction of movement or rotation.

[0020] Preferably, the sensor is arranged in a plane perpendicular to the rotation axis of the flowmeter, and the sensor is arranged on a radial line originating from the rotation axis of the flowmeter (particularly the impeller of the flowmeter), wherein the radial line encloses an angle. By providing an angle between the measurement positions of the two signals from the two sensors, the signals generated by the sensors have a phase difference relative to each other. This is especially true when the rotation speed is constant. Preferably, this angle can be between 45° and 135°, more preferably between 80° and 100°. The angle can be 90°, producing a signal out of phase by 90°. This configuration corresponds to a typical quadrature encoder. The 90° angle is particularly advantageous in terms of robustness against fluctuations in rotational rate. However, it must be understood that any angle that allows the rotational direction to be evaluated via a phase difference can be used.

[0021] For rotary encoders (such as bipolar magnets), a dual-channel signal (where the signal switches with each sensed or detected change in the direction of the magnetic field) allows the determination of the rotational direction and speed of the rotating element.

[0022] Preferably, the control circuit is configured to provide a control signal that instructs the valve to close when the determined flow direction is reversed. The control signal can be received by the valve's control circuit, which opens or closes the valve in response to the control signal. The control signal can be a TTL signal or an indication of true or false status. Providing a control signal indicating whether the valve should be closed or open allows the system to operate with different types of valves. For example, the valve can be an electrically controlled water valve or a stop valve.

[0023] Preferably, the control circuit includes a direction detection circuit that analyzes the dual-channel signals to determine the rotation direction of the flowmeter impeller. The direction detection circuit can provide the result as a signal. The signal can be a digital signal encoding the result, where the result can be either forward or reverse water flow. The signal can be a true signal or a false signal, where a true signal corresponds to forward water flow and a false signal corresponds to reverse water flow. The signal can be a TTL signal or an analog voltage. In principle, the signal can be any two-state signal.

[0024] Preferably, the control circuit further includes a determining circuit that compares the determined flow direction with a preset flow direction and generates a Boolean signal indicating whether the determined flow direction matches the preset flow direction. The system also includes an AND gate, where the Boolean signal generated by the determining circuit is provided to the AND gate. Furthermore, the system includes an electronic control circuit that controls the inflow rate by providing the Boolean signal to initialize the water flow. The electronic control circuit provides the signal to the AND gate, which is connected to the signal input of a stop valve. Preferably, the direction detection circuit can receive dual-channel signals and determine the flow direction through the flow meter based on the dual-channel signals. The determining circuit can receive a signal indicating the flow direction from the direction detection circuit, for example, in the form of a Boolean signal, where true indicates forward and false indicates reverse. However, any suitable signal can be used. The determining circuit may have stored a normal direction corresponding to normal operation (i.e., forward flow). The determining circuit can have a Boolean value or value corresponding to the forward-associated signal received from the direction detection circuit. For example, true can correspond to forward. In this case, the true signal received from the direction detection circuit is identified as indicating forward. Therefore, the determining circuit matches the received signal with the stored signal associated with the positive direction. If the determining circuit determines that the signal matches the stored signal, the determining unit can provide an OK signal, such as a true signal, a high signal, or a corresponding analog voltage. If the received signal does not match the value or signal associated with the positive direction, the determining unit provides an ERROR signal, such as a false signal, a low signal, or a corresponding analog voltage. The determining circuit provides the generated output signal to a logic AND circuit. The logic AND is connected to a valve configured to close the water supply to an appliance. This configuration allows for further conditions to allow water to flow between the water supply system and the appliance, because each input of the AND circuit requires two true signals to provide a true signal to the valve or the valve's control circuitry. For example, an additional true signal generated by the appliance's electronic control circuitry indicates that the appliance needs water. Furthermore, if the determining circuit provides an ERROR signal, the water flow will immediately stop because a false signal will cause the AND output to be false. Therefore, regardless of whether the electronic control circuitry needs more water, the valve will stop as soon as backflow is determined.

[0025] Preferably, the circuit, particularly the determining circuit, provides an error signal when the flow direction is reversed, and wherein the determining circuit provides an OK signal when the flow direction is forward. By providing logic signals, the control logic of the valve or the AND circuit can be operated.

[0026] Preferably, the system includes a valve. The valve can be connected to a control circuit, particularly a determining unit, which allows for the provision of a valve that can be controlled by the circuit.

[0027] Preferably, the valve is a water valve or a stop valve at the inlet of the electrical appliance. The system is adapted to provide a signal that allows control of the stop valve or the water valve at the inlet, thereby allowing interoperability with known systems (e.g., stop valves). Therefore, the system can be easily integrated into existing solutions. Furthermore, the system avoids additional mechanical components in the water flow path that could be damaged by water if existing valves are used.

[0028] Preferably, the flow meter includes an impeller and a magnet that rotates with the impeller. Specifically, the magnetic poles of the magnet rotate in a circle around the axis of rotation of the impeller. The magnet can act as an encoder for the impeller. The encoder may include at least two, four, or any even number of magnetic poles. Providing an orthogonal encoder linked to the impeller allows the determination of the impeller's rotational frequency, thereby determining the volume of water flowing through the flow meter and the direction of water flow.

[0029] Preferably, the magnet is a bipolar magnet, and the poles rotate in a circle around the axis of rotation of the flowmeter. This solution uses only one signal magnet. Therefore, the solution is inexpensive and allows for at least one signal to be provided with each rotation. The system may include annular or disc magnets or arrangements of magnets comprising any even number of poles. These solutions advantageously improve resolution. Thus, a magnet with four or more poles allows backflow to be detected in less than half a rotation of the flowmeter. Therefore, backflow stops earlier compared to a magnet with only two poles. Preferably, when using more than two magnets, the sensors are arranged at an angle relative to each other determined by dividing 180° by the number of poles. For example, with two poles, the sensors are arranged at a 90° angle. When using four poles, the sensors may be arranged at a 45° angle, and so on.

[0030] In another aspect of the disclosed technology, a component for a household appliance is provided, including the system described above. The system can be integrated with components of the household appliance (e.g., a dishwasher or washing machine). The component may be part of the appliance's water inlet system.

[0031] Preferably, the component includes an inlet chamber. By providing additional sensors and modifying existing control electronics, this allows the use of existing components for electrical appliances, particularly the inlet chamber, which already include a single-channel flow meter. Compatibility is ensured because the component is compatible with the electrical appliance.

[0032] Preferably, the flow meter is positioned at the inlet of the inlet chamber. Therefore, the flow direction is determined upstream of the water buffer in the electrical appliance.

[0033] In another aspect of this disclosure, a household appliance comprising the above-described system is proposed. The household appliance may be a dishwasher or a washing machine. The household appliance includes the above-described system and provides a control signal to the appliance's shut-off valve.

[0034] In another aspect of the disclosed technology, a method for preventing backflow from a household appliance is provided. The method includes determining the flow direction through an inlet of the household appliance, and providing a control signal to a valve located upstream of the inlet of the household appliance based on the determined flow direction. Therefore, once backflow is detected, the valve shuts off the water flow. This method can be applied to appliances to meet regulatory requirements by providing an additional mechanism to prevent backflow into the water supply system.

[0035] Preferably, the method further includes generating a control signal based on the determined flow direction and providing the control signal to a valve located upstream of the inlet of the household appliance, wherein the control signal instructs the valve to close if the determined flow direction is reversed. According to the method, the valve is closed based on the control signal. Therefore, this method allows control of commonly used valves to interrupt water flow between the water supply system and the appliance.

[0036] In another aspect of the disclosed technology, the use of quadrature encoders for determining the flow direction in household appliances is proposed. An advantage of using quadrature encoders is that existing household appliances (such as dishwashers or washing machines) typically include single-channel flow meters, which can be modified by adding another magnetic sensor or by replacing the single sensor with two magnetic sensors (such as reed sensors, Hall effect sensors, or magnetoresistive (MR) sensors) to provide dual-channel signals with a 90° phase offset between channels. Therefore, using quadrature encoders to determine the direction of water flowing through a household appliance is easy and inexpensive to implement. The use of quadrature encoders also allows for easy implementation of flow detection because only one or two additional signals are needed, for example, these signals can be provided to existing control circuitry that controls valves or switches relays already connected to the appliance.

[0037] Preferably, the quadrature encoder is used according to the above system, wherein the quadrature encoder is part of a flow meter downstream of the inlet of the household appliance and provides a dual-channel signal based on the rotation of the impeller of the flow meter. Attached Figure Description

[0038] Figure 1 An illustrative quadrature encoder is shown.

[0039] Figure 2 The signals of two channels of the quadrature encoder are shown.

[0040] Figure 3 The signals of two channels of the quadrature encoder are shown.

[0041] Figure 4 The flow meter is shown.

[0042] Figure 5 A schematic diagram of an existing technology system is shown.

[0043] Figure 6 A schematic diagram of the present invention is shown.

[0044] Figure 7 A schematic representation of the method according to this disclosure is shown. Detailed Implementation

[0045] The disclosed technology generally utilizes a quadrature encoder to detect the direction of water flow through a flow meter. A quadrature encoder is an incremental encoder that converts angular or linear position information into digital signals for use by a motion control system.

[0046] Figure 1 A schematic diagram of a quadrature encoder is shown. The encoder includes a rotating component 101 and two sensors 2a and 2b. The rotating component 101 acts as the encoder by providing an alternating signal. The encoder can be attached to the rotating component of a device. For example, a disk or toroidal magnet can rotate around an axis, or a linear magnet can rotate around an axis. Figure 1In this design, rotating magnet 101 is a bipolar magnet that rotates about an axis. Rotating magnet 101 can be a toroidal magnet. The rotating element can have alternating north and south poles arranged in a specific pattern. For example, one half of the toroidal magnet can be the north pole, and the other half can be the south pole, thus providing different magnetic field orientations every 180° of rotation of the toroidal magnet. Two sensors 102a, 102b, particularly magnetic sensors (such as Reid sensors, Hall sensors, or any other magnetoresistive sensors), are arranged at a preferred angle of 90°. This angle can be arbitrary. The sensors provide two signals on two signal channels, Ch A and Ch B. The signals are out of phase as the encoder rotates. The phase difference is caused by the different positions of the sensors. Sensors 102a, 102b can be out of phase at a predetermined angle. The sensor signals are preferably 90° out of phase. The sensors are arranged such that the encoder or rotating element must rotate 90° so that the second sensor detects or measures the same encoder portion as the first sensor. The sensors detect changes in the magnetic field or the direction of the magnetic field and provide corresponding output signals on the respective channels. The sensors generate signals based on the magnetic field. For example, a sensor can provide a signal with two states, such as high and low. If the detected magnetic field corresponds to the North Pole, the sensor provides a signal based on one of the states; if the detected magnetic field corresponds to the South Pole, it provides a signal. Therefore, the signal indicates the direction or orientation of the magnetic field. The sensor can change the state of its output signal as the orientation of the detected magnetic field changes. Therefore, the signal can indicate a change in the direction of the magnetic field.

[0047] A preferred 90-degree phase difference between the two signals allows the system to determine the direction of motion. Specifically, when each sensor provides a signal for its corresponding sensor channel, the direction can be determined based on which of the two sensor channel signals is leading. For example, the signal that transitions from a low state to a high state before the other channel signal switches from low to high is leading.

[0048] Figure 2 and Figure 3 This illustrates two signals from a two-pole encoder rotating in both clockwise and counterclockwise directions.

[0049] exist Figure 2 In this case, channel A leads channel B, and the movement is in a specific direction (e.g., clockwise).

[0050] exist Figure 3 In this case, channel B leads channel A, and the direction of movement is in the opposite direction (e.g., counterclockwise).

[0051] Those skilled in the art will understand that the correspondence between the direction of rotation and which signal is leading depends on the specific arrangement, particularly the geometry of the sensors, the definition of which channel is which, and which magnetic orientation or magnetic transition corresponds to the high and low portions of the signal. Control electronics or circuits can be programmed according to this specific arrangement to determine the direction of rotation.

[0052] Therefore, the quadrature encoder 100 provides two signals via two channels relative to the two sensors 102a, 102b to allow determination of the rotational direction of the encoder plate 101 (e.g., a magnet rotating about an axis, particularly a toroidal magnet). Quadrature encoders are known in the art. A quadrature encoder includes circuitry that determines direction based on the corresponding sensor signals received via the two channels. In the same manner as an incremental encoder, the quadrature encoder can still count the number of increments to determine how far the rotating element has moved or how many rotations the rotating element has performed.

[0053] Figure 4A typical design of a flow meter 400 is shown. For example, a flow meter 400 used in a washing machine or dishwasher allows control electronics to determine the amount of water flowing into the appliance. The flow meter 400 has an inlet 401 and an outlet 402. In other embodiments, the configuration of the inlet 401 and outlet 402 is reversed without affecting the ability to detect the flow direction. The flow meter includes an impeller 403 driven by water flowing from the inlet to the outlet, i.e., the impeller 403 is arranged such that the blades of the impeller 403 are struck by the water flow on one side of the impeller relative to the axis of rotation 405. The impeller 403 may include a magnet 404, such as an annular magnet acting as an encoder disk. The water flow causes the impeller 403 to rotate, and the alternating magnetic field induces an alternating signal in a corresponding readout sensor (not shown), so that each time the direction of the magnetic field changes (e.g., in response to a change in the direction of the magnetic field caused by the annular magnet acting as an encoder), the corresponding readout sensor can generate a signal. In other words, the flow meter can generate a so-called tacho-signal or act as a frequency generator. For example, during a full rotation of impeller 403, the bipolar magnets will cause the magnetic field detected by the sensor to change from one orientation to another. Therefore, the sensor can provide a signal that is in one state when the impeller rotates 180° and in a second state when the impeller rotates another 180°. Thus, when the impeller rotates at a constant speed, the sensor can generate a signal with a constant frequency corresponding to the rotational frequency of the impeller. Adding an additional set of alternating magnetic poles, causing the magnetic field at the sensor to alternate from north to south, then back to north, and back to south during a full rotation, will result in the frequency of the sensor's output signal being twice the rotational frequency of the impeller. Therefore, the flowmeter counts the rotation or the frequency at which the encoder or a portion of impeller 403 passes through the sensor. Thus, the speed of the flowmeter can be determined, but there is no information about the direction of rotation of impeller 403. Reverse rotation will result in a signal with the same frequency.

[0054] Figure 5 A schematic representation of a prior art flow meter in a household appliance (such as a dishwasher or washing machine) is shown.

[0055] The appliance is connected to the domestic water supply system 501 via valve 502 (e.g., a stop valve), which shuts off the water supply in the event of a leak or malfunction. Stop valves, commonly used in washing machines and dishwashers, are a safety feature designed to prevent leaks and flooding. The stop valve system typically consists of double-walled hoses. The inner hose delivers water to the appliance, while the outer hose is designed to contain any water that may leak from the inner hose. A pressure sensor or float switch is mounted at the end of the outer hose, near the appliance's connection point. This sensor detects the presence of water in the outer hose. When the sensor detects water, it triggers the stop valve to close. This valve is typically located at the connection point between the hose and the water supply system. The stop valve may be connected to the appliance's control electronics.

[0056] The electrical appliance is connected to the domestic water supply system 501 via a hose, which can be a commercially available water-stop system hose as described above. The water-stop valve 502 or water valve 502 as described above is placed in the water flow path between the inlet of the electrical appliance and the domestic water supply system 501.

[0057] Such as about Figure 4 In general description, a flow meter 503 is arranged within an appliance, located downstream of the water flow during normal operation (i.e., water flowing from the water supply system into the appliance). The flow direction from the water supply system to the appliance is forward flow, and the flow direction from the appliance to the water supply system is reverse flow. The flow meter 503 measures the water velocity or the amount of water entering the appliance. For example, the water volume is determined by generating a rotational speed signal based on the rotational speed of the flow meter's impeller. The water flow, velocity, or volume is determined by a control circuit 504 based on signals received from the flow meter 503. The flow meter 503 provides a single-channel signal. The flow meter 503 may include an impeller that rotates about a rotating axis. The inflowing water drives the impeller, thus allowing the flow meter to determine the water flow, velocity, or volume. The flow meter may include a two-pole annular magnet that rotates with the impeller.

[0058] For example, flow meter 503 includes a sensor (e.g., a Reid or Hall sensor) that reads the orientation of the magnetic field of a rotating magnet that rotates with an impeller driven by the flow of water entering through flow meter 503. The magnetic sensor (e.g., a Reid or Hall sensor) provides a signal that changes at least once every half revolution. Therefore, counting the changes in the signal allows the rotational speed of the annular magnet to be determined, thereby determining the rotational speed of the impeller. The outlet of flow meter 503 can be connected to an electrical flushing chamber 505.

[0059] The appliance may include a water buffer, such as an inlet chamber. The inlet of the water buffer may be connected to the inlet of the household appliance. The water buffer may include a flow meter 503, wherein the inlet of the flow meter is connected to the inlet of the water buffer, and the outlet of the flow meter is connected to the water storage chamber of the water buffer.

[0060] Electronic control circuit 504 can control valve 502. The electronic control circuit can control water flow according to a predetermined program or based on internal sensors of the household appliance. In the event of a detected fault (e.g., a leak), the control circuit can close the valve. The electronic control circuit can consider the measured flow rate to determine the amount of water received by the appliance. The electronic control circuit can control the appliance based on the detected water volume. The electronic control circuit can open the valve only when the appliance needs or requests water from the water supply system 501.

[0061] Figure 6 This is a schematic representation of an anti-backflow system based on the technology of this disclosure. Figure 5The prior art system. Valve 602 is placed in the flow path of water flowing from domestic water supply system 601 to the inlet of the appliance. Flow meter 603 according to this disclosure is arranged downstream of the inlet of the appliance. The system includes a flow meter. The flow meter includes two sensors and a magnet mounted on the impeller of flow meter 603. The magnet is mounted such that its north and south poles are arranged adjacent to each other on the circumference of the impeller's axis of rotation. The sensors are magnetic sensors. The magnetic sensors can be Reid sensors, Hall effect sensors, or any other sensors suitable for measuring changes in magnetic fields or their direction. The two sensors and the magnet are configured to form an orthogonal encoder. Therefore, the system includes an orthogonal encoder that measures the speed and direction of rotation of the impeller of flow meter 603. The two sensors generate two signals provided via signal channels A and B, as described above regarding... Figures 1 to 3 As described, the two sensors are placed at a 90° interval (orthogonal) relative to the impeller motion. This disclosure is not limited to placing the sensors at a 90° interval, as any phase shift that allows for the determination of motion and direction is sufficient in the context of this disclosure. As the impeller rotates, the sensors preferably generate signals that are 90° out of phase. Each sensor generates, for example, a square wave signal based on the alternating direction of the detected magnetic field generated by a magnet that moves with the rotation of the impeller. For a 180° rotation, the sensor detects the north pole of the magnet in principle, and for another 180° rotation, the sensor detects the south pole. The phase difference between the signals from the two sensors corresponds to the angle between the two sensors, which is defined between two lines passing through each sensor from the center of the impeller.

[0062] The flow meter 603 of this disclosure generates a dual-channel signal with phase shift based on the arrangement of sensors. The direction of rotation of the flow meter can be determined based on the phase shift, and correspondingly, the direction of water flow through the flow meter can be determined. Magnetic elements rotating with the flow meter 603 (particularly the impeller of the flow meter 603) can define a magnetic mode; for example, the magnet can have four alternating north and south poles. In particular, an encoder disk, which can be composed of a magnet or several magnets, can have any even number of alternating north and south poles.

[0063] System 600 also includes a direction detection circuit 606 to determine the flow direction by determining the direction of rotation of the impeller of the flow meter. The direction detection circuit 606 receives dual-channel signals from the flow meter 603 (specifically from a sensor of the flow meter 603) and determines which signal leads the other. For example, a signal from channel A leading the signal from channel B may correspond to a forward flow direction, i.e., flow from the inlet of the appliance through the flow meter into the appliance, for example, into the appliance's flushing chamber. In this case, a signal from channel B leading the signal from channel A indicates a reverse or opposite flow direction, i.e., flow from the appliance through the inlet towards the domestic water supply system. Those skilled in the art will understand that the correspondence between which channel leads and the flow direction is determined by the specific arrangement. This disclosure covers any combination. For example, channel B leading channel A may correspond to a forward flow. The correspondence between which channel leads and the flow direction is determined during the setup of the control electronics, such as during manufacturing. This correspondence may be programmed or hardwired into the circuitry of the device.

[0064] System 600 may further include a determining circuit 607 that determines whether the flow direction corresponds to a positive direction based on a signal received from the flow direction detection circuit 606. In other words, the determining circuit 607 compares the direction determined by the direction detection circuit 606 with a predetermined flow direction. The predetermined flow direction may be a positive flow direction. When the signal received from the direction detection circuit 606 indicates that the flow direction is positive, the determining circuit may generate a signal indicating normal flow, such as a true signal, in the form of a high TTL signal or an analog voltage defining a high or true state. When the direction detection circuit 606 determines that the flow direction is reversed, the determining circuit 606 generates an error signal. In particular, since the determining circuit 607 determines that the direction indicated by the signal received from the direction determining circuit 606 does not match the predetermined direction corresponding to the flow direction under normal operation. For example, when the direction indicated by the signal received from the direction detection circuit 606 does not match the predetermined direction (e.g., positive) under normal operation, the determining circuit 607 may generate a false signal in the form of a low TTL signal or an analog voltage defining a low state. Those skilled in the art will understand that, by definition, the true and false states and the high and low states can be arbitrarily interchanged; that is, the OK state can be indicated by a low signal, while the ERROR state can be indicated by a high signal.

[0065] The determining circuit 607 can provide a signal to the valve 602. When the signal indicates an OK state, the valve opens or opens in response to the OK signal. The valve 602 may include internal circuitry (or a valve driver) that opens or closes the valve based on a received control signal. Specifically, the valve driver can be used to switch the valve 602 based on a logic signal (such as a TTL signal) or a software state (such as a state variable) to adapt a given logic signal to an appropriate valve switching signal. In some embodiments, a valve driver (not shown) is provided between the AND circuit 608 and the valve. In some embodiments, the valve 602 is an AC valve, for example, driven by 230V AC. In such embodiments, the valve driver may be provided, for example, in the form of a TRIAC. In some embodiments, the valve 602 is, for example, a DC valve driven by a DV voltage between 12V and 320V. In such embodiments, the valve driver may be provided in the form of a transistor, such as a bipolar transistor or a field-effect transistor (FET).

[0066] Preferably, the determining circuit 607 can provide the generated signal to the logic AND circuit 608. The logic AND circuit 608 can be connected to the valve. In other words, the determining circuit 607 can be connected not directly to the valve, but via the logic AND circuit 608.

[0067] The household appliance may also include an electronic control circuit 605 for controlling its operation. For example, the electronic control circuit 605 may receive at least one signal from one channel of the flow meter 603 to determine the amount of water in the appliance. Therefore, the electronic control circuit 605 may receive only the rotation speed signal from the flow meter. However, the electronic control circuit 605 may also receive a complete dual-channel signal generated by a sensor of the flow meter 603. The electronic control circuit 604 may control the operation of the appliance based at least in part on the determined amount of water flowing into the appliance. The electronic control circuit 604 may control operation based on measurements from sensors in the rinsing or washing chamber. If the electronic control circuit 605 determines that additional water is needed, it may provide a true signal to the logic AND 608. Therefore, when the control electronics request water and the signal from the determining circuit 607 is true (i.e., the flow direction is positive), AND generates a true signal at both inputs and provides the true signal to the valve. Upon receiving the true signal, the valve 603 opens, allowing water to flow into the household appliance. Therefore, the valve will only open if the water flow is forward and the electronic control circuit 604 requests water. As long as the determining circuit 607 does not determine that the flow direction indicated by the signal provided by the flow direction detection circuit 606 indicates a reverse flow direction, the determining circuit 607 can be configured to provide an OK signal, such as a high signal. In other words, the output of the determining circuit 607 is true except when indicating reverse flow. Therefore, the determining circuit 607 can be configured to output a signal in one state (e.g., high) and switch the signal to another state (e.g., low) only when the flow direction is reversed.

[0068] When the control electronics 605 requests water, the AND circuit 608 provides a true signal. If the flow direction is not reversed, the determining unit also provides a true signal, and the AND circuit sends a true signal to the valve. The valve can open in response to the true signal to open the valve.

[0069] For example, if the pressure in the water supply system 601 drops and causes water to be drawn from the appliance, the impeller of the flow meter reverses its rotation direction. This causes the flow meter's dual-channel signal to correspond to a signal indicating reverse rotation. For example, the sign of the phase difference between the signals on the two channels of the flow meter signal changes. The flow direction determination circuit 606 determines the flow direction reversal, i.e., reverse, based on the dual-channel signal, and the determination circuit 607 indicates an ERROR state by providing a false signal to the logic AND circuit 608 when it receives the corresponding signal from the direction detection circuit 606. Since one of the inputs to the logic AND 608 is low, the output is low, and the signal sent to the valve is low. Based on the high-to-low signal provided to the valve by AND 608, the valve 602 closes. The flow meter 603 has two sensors, and these two sensors generate a dual-channel signal, which allows the direction to be determined within one revolution, and the valve closes before a large amount of water downstream of the flow meter can flow out of the appliance's inlet.

[0070] Therefore, the system of flowmeter 603, which acts as a quadrature encoder, includes two sensors that provide dual-channel signals based on the position of an encoder disc in the form of bipolar magnets. Electronic evaluation of these signals provides a corresponding control signal to the valve, offering an effective measure to prevent backflow from electrical components to the water supply system. By adding a second sensor, the system can be applied to known systems that already have a flowmeter (which can only measure the impeller speed using a single sensor).

[0071] Figure 7 This is an illustrative representation of the method according to this disclosure. In step S1, the flow direction through the flow meter of the household appliance is determined. In step S2, a control signal is generated based on the determined flow direction, specifically by comparing the determined flow direction with a forward flow direction. If the determined flow direction matches a forward flow direction, the control signal indicates that the valve between the water supply system and the appliance inlet can be opened. The control signal can be a true signal. If the determined flow direction is reversed, the control signal indicates that the valve should be closed, for example, the control signal is a false signal or is in a false state. In step S3, if the determined flow direction is reversed and the control signal indicates that the valve should be closed, the valve is closed.

[0072] If reverse flow is detected, then utilize Figure 6 The system shown will shut off the valve upstream of the appliance's inlet.

[0073] The various components or functions of the disclosed technology are described in the embodiments and corresponding examples as software or hardware solutions. However, this does not mean that a function described as a software solution cannot be implemented in hardware, and vice versa. Similarly, those skilled in the art will also conceive of hybrid solutions in which components and functions are implemented partly in both software and hardware.

[0074] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" does not exclude a plural.

[0075] A single unit or device can perform the functions of multiple elements listed in the claims. The fact that various functions and elements are listed in different dependent claims does not mean that combinations of these functions and elements cannot be used advantageously.

Claims

1. A system for preventing backflow from a domestic appliance, wherein the system comprises: a flow meter (603) for measuring a water flow, wherein the flow meter (603) comprises a quadrature encoder providing a two-channel signal, and a control circuit (606, 607) configured to: determine a flow direction based on a first signal of a first channel and a second signal of a second channel, and provide a control signal for a valve (602) based on the determined flow direction.

2. The system according to claim 1, wherein the quadrature encoder comprises two sensors and a magnet, and wherein the first sensor provides the first signal provided on the first channel, and the second sensor provides the second signal provided on the second channel.

3. The system according to any of the preceding claims, wherein the sensors are arranged in a plane perpendicular to an axis of rotation of the flow meter, and wherein the sensors are arranged on a radial line originating from the axis of rotation of the flow meter, and wherein the radial line defines an angle.

4. The system according to claim 3, wherein the angle is between 45° and 135°, preferably between 80° and 100°, more preferably wherein the angle is 90°.

5. The system according to any of the preceding claims, wherein the control circuit (607) is configured to provide a control signal indicating the valve (602) to be closed in case the determined flow direction is reverse.

6. The system according to any of the preceding claims, wherein the control circuit further comprises: a direction detection circuit (606) configured to determine a flow direction based on the two-channel signal, and a determination circuit (607) configured to compare the determined flow direction with a preset flow direction and generate a Boolean signal indicating whether the determined flow direction matches the preset flow direction, wherein the system further comprises: an AND gate (608), wherein the Boolean signal generated by the determination circuit (607) is provided to the AND gate, and an electronic control circuit (605) controlling the amount of water in by providing a Boolean signal to initiate water flow and providing a signal to the AND gate (608), wherein the AND gate (608) is connected to a signal input of a valve (602).

7. The system according to any of the preceding claims, wherein the system comprises the valve.

8. The system of claim 2 or any one of claims 3 to 7 as dependent on claim 2, wherein the flow meter comprises an impeller, and the magnet rotates with the impeller, wherein, the magnet is a two-pole magnet, and the magnetic poles rotate on a circumference around an axis of rotation of the flow meter.

9. An assembly for a domestic appliance comprising the system according to claim 1.

10. The assembly of claim 9, wherein, the assembly comprises a water inlet cavity, wherein the flow meter is arranged at an inlet of the water inlet cavity.

11. A domestic appliance comprising the system according to claim 1, wherein the system provides a control signal to a water stop valve of the domestic appliance.

12. A method for a domestic appliance, the method comprising the steps of: determining (SI) a flow direction through an inlet of a domestic appliance; - providing (S2) a control signal to a valve arranged upstream of the inlet of the domestic appliance based on the determined flow direction.

13. The method according to claim 12, further comprising: - generating (S2) a control signal based on the determined flow direction, - providing (S3) the control signal to a valve arranged upstream of the inlet of the domestic appliance, wherein in case the determined flow direction is reversed, the control signal indicates to close the valve, and - closing the valve according to the control signal.

14. Use of a quadrature encoder for determining a flow direction in a domestic appliance.

15. The use of a quadrature encoder according to claim 14, wherein the quadrature encoder is part of a flow meter downstream of an inlet of the domestic appliance and provides a two-channel signal according to a rotation of an impeller of the flow meter.

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