SYSTEM AND METHOD FOR CORRECTING THE ROTATION DIRECTION OF A

TWO-POLE MOTOR APPLIED TO A TWO-WAY PUMP Field of the invention

The present invention relates to the field of electromechanical engineering, more specifically, electromechanical devices, commonly known by household appliances, specifically a system comprising a pump coupled to a synchronous two-pole motor and a method of identification and correction of the direction of the associated rotation applied to washing machines.

Background of the invention

The rotation from electrical motors is the base mechanism for many household appliances. At times, this rotation movement is obvious, as in fans or cake mixers, but often remains somewhat disguised, as in the agitators of washing machines or electric windows from the windows of some cars, by being hidden in the operation mechanism of such equipment. Electrical motors are encountered in the most various shapes and dimensions, each appropriated to its respective task and function to which is intended. The motor rotor needs an initial torque to begin running. Such torque, also known as momentum, is commonly produced by magnetic forces developed between the magnetic poles of the rotor and the stator ones. Attraction or repulsion forces, developed between the stator and rotor, pull or push the moving poles of the rotor, producing torque, which makes the rotor to spin faster and faster, until the friction or loads connected to the shaft reduce torque, reaching a minimum value of the resultant force. At this point, the rotor spins with a constant angular speed, maintaining the spin.

Both the rotor and the stator of the motor must be magnetic, as they are the forces between the poles that produce the torque required to spin the rotor. The rotor is a permanent magnet that spins between two stationary electromagnets. As the electromagnets are powered by alternating current, their poles reverse their polarity as the direction of the current also reverses. Thus, the rotor spins when its north pole is pulled firstly to a first electromagnet, south, and pushed by a second electromagnet - north. Each time the rotor north pole is about to reach the south pole of a stationary electromagnet, the current reverses and such south pole becomes a north pole, alternating the forces that 'push' and 'pull' the rotor. The rotors keeps spinning continuously, ending a turn to each cycle of the alternating current. As it rotates perfectly synchronized with the reversals of alternating current, this motor is called synchronous electric motor of alternating current. This process can be better understood by looking at Figure 1. The water pumps motors with an inlet and an outlet, applied to washing machines, for example, are this type.

The water pumps used in washing machines are designed to implement this fluid drainage during washing and often are used to recirculate the liquid, i.e. move continuously the water that is present in the bottom of the machine to the top. There are ways to improve the drainage and recirculation operation, avoiding the use of two water pumps. One of them is the use of a regular pump, coupled to a flow directing valve. Another one, less common, is to use a pump with an inlet and an outlet, also known as Y pump, which uses an outlet for drainage and other for recirculation. Through the rotation direction control of the pump, one can control the direction of water flow to one of the mentioned outputs. Typically, the engine used for this purpose has over two poles, and may thus create a displacement of the rotor in less than 180 °, allowing, with this shorter displacement, to force a specific rotational direction to the shaft. The drawback of such engines is its constructive complexity, a fact which leads to a higher cost. The water pumps motors, commonly used in washing machines, have only two poles, and can thus align the poles in only two points, in an angle of 180 degrees between them. This precludes the creation of an efficacious control to assign the direction of rotation of the motor. These engines are used in a pump with an inlet and an outlet, no matter in which direction, as for any of the directions the water is pumped to the same outlet.

The drawback resides in the fact of how to control a pump that has two outlets with a simplified operation, in which is not possible to control the initial direction of rotation. There is no economical and simple solution known to combine these processes. It is necessary to know which way the rotor is spinning, because in some pumps there may be an element of derivation (commonly called flap) that switches according to the rotation of the rotor.

In order to solve this problem we have developed a system powered by a two-pole single-phase motor, applied to a two-way pump, commonly applied to the discharge of washing machines, combined with a method of identifying and correcting the rotation direction.

Analysis of the state of the art

The patent US3773432, from July 13, 1971 describes a bi-directional turbine pump for selective fluid flow through two different discharges, depending on the direction of rotation of the propeller. This document presents a pump with an inlet and two outlets, however without defining a method associated to perceive the rotation direction of the motor.

The invention US4091644, from April 08, 1977, relates to a reversible turbine pump that allows the selective fluid flow in two different directions. This document presents a pump with an inlet and two outlets, however without defining a method associated to perceive the rotation direction of the motor.

The document US5493745 describes a washing machine that recirculates and frains water by means of a reversible pump and two valves of two-way that determine the fluid flow pumped, for recirculation or for flow.

The patent GB 1218724 from March 02, 1968 relates to a pump associated to a rotor, preferably of two poles, without commutation and whose rotor is mounted in a sealed chamber of a pump and having position sensors that receive the permanent magnet position to control de commutation circuit, however, the document does not advances the application of this motor in a "Y" pump having an inlet and two outlets.

The invention WO 2007/053042 describes a washing machine with recirculation, highlighting a speed control, even though it refers to a three- phase motor applied to a two-outlet pump.

Brief description of the invention

This invention describes a system and a method for identifying and correcting the rotation direction of a synchronous motor that drives a two- way pump applied to washing machines, such a method that allows the use of a more cost effective motor in washing machines. The speed control of the motor also provides more accuracy to the process, preventing water wastes.

The solutions uses a two-pole motor associated to an innovating method to detect the rotation direction and speed control of the motor, thus reducing costs because of the simplified construction of such motors.

Additionally, the speed control step of the motor prevents the unnecessary flow of water, avoiding waste.

The solution also features a system equipped with a pump with an inlet and two outlets, supplied with sensors and two-pole single phased motor driven using the proposed method, providing a constructive simplicity and therefore a lower cost. The system also contemplates an electro-electronic circuit supplied with a microprocessor programmed with reference values. Description of drawings

Figure 1 reveals an operation scheme of synchronous two-pole motors, where can be identified the iron cores (6) that influence the permanent magnet (7) fixed to a central shaft (8) in order to spin freely when the power source (9) of alternating current actuates.

Figure 2 reveals a schematic upper perspective view of the pump with its components: inlet duct of liquids (1), outlet duct for recirculation (2), discharge duct (3), valve (4), propellant (5) and motor (1 1).

Figure 3 reveals a schematic upper perspective view of the Y pump with its components: inlet duct of liquids (1), outlet duct for recirculation (2), discharge duct (3), valve (4), propellant (5) and motor (1 1).

Figure 4 provides a schematic view of the Y pump application (10) in a washing machine, highlighting a recirculation duct (12), discharge duct

(13) and cleaning liquid (14).

Figure 5 demonstrates the synchronous motor rotation direction correction method workflow.

Figure 6 shows a speed control method workflow, applied consecutively to the rotation direction correction method.

Detailed description of the invention

This invention relates to a system comprised by an electro-electronic circuit (not illustrated), means of detection of the motor rotation direction (11) and a synchronous two-way pump (10), also known as Y pump, supplied with a two-pole single-phased motor (1 1), associated to a method for identifying and correcting the rotation direction of the propellant (5).

The pump (10) is commonly applied to washing machines aiming at the discharge to one of the ways of the Y pump (10) and recirculation to another way of the same Y pump (10).

Thus, when the pump is actuated (10), the propellant (5) moves, driving the liquid inserted through the inlet duct (1) to the outlet, which could be through the outlet duct for recirculation (2) or through the discharge duct (3), separated physically through the valve (4) that directs the liquid flow according to the rotation direction of the rotor (5).

When the pump is activated (10), the two-pole motor (11) spins in any and unpredictable direction. Specific sensors allocated in any positions where they can perceive the rotation direction, like, for instance, in outlets (2 and 3) of the Y pump (10), at the pump housing (10), at the rotor shaft, at the propellant or even on the pump wall (10), associated to a specific computer application, perceive the rotation direction driven to the propellant (5). If the spin direction of the propellant (5) is perceived by the sensor as the direction reverse to the programmed at the machine, the voltage supplied to the motor (1 1) is stopped, preventing the operation of the Y pump (10). Then, a new charge is applied to the motor (1 1), resuming the process from the beginning, repeatedly, until the spin rotation is according the programming of the washing machine. If the direction is according the one previously adjusted in the machine, the pump (10) runs correctly.

The method can be briefly summed up by the following steps: power supply to the motor (1 1); the sensor perceives the rotation direction of the motor (10) and checks if the direction is the equal to the one programmed at the washing machine. If not, it stops the power supply and restarts the cycle. If so, it continues the operation according to the programming of the washing machine. The method is clarified by the logic workflow of the method shown in Figure 5.

This first embodiment defines a method simplified for detecting and correcting the rotation direction of a Y pump (10), applicable to any pumps for detecting the rotation direction.

In a preferred embodiment, the described method uses an electro-electronic system (not illustrated), comprised by sensors and a digital electronic set, controlled by a microprocessor, which has an application previously defined for such functions, with the reference values, which runs the whole method functioning logic, connected to actuators that make the interface with the motor (1 1) of the pump (10).

In an additional embodiment, the method previously approached incorporates the speed control of the rotation of the motor (11) and consequently the water flow control driven by the Y pump (10). This speed control of the motor (1 1) of the pump (10) avoids water wastes, since, by previously identifying the rotation direction, prevents the unnecessary water flow.

The application operation can be briefly described as follows: request water flow through a duct (12 or 13); turn the pump on (10) at low rotation and check if the rotation direction is correct. If not, turn the pump off (10), wait the water to return and restart the cycle. If so, increase speed of the pump (10) in order to enter the water flow range and indicate to the application that the position is proper to run the flow. The operation of the speed control can be better understood by looking at Figure 6.

During the detection step of the rotation direction, the flow of the Y pump (10) is insufficient to cause the water to flow, since the pressure created by the pump (10) is smaller to the water column in the ducts, but sufficient to allow the detection of the rotation direction. Figure 4 clarifies the pump position (10) in relation to ducts and heights of the column of water.

Alternatively, one can use only the speed control of the rotation direction, without using the speed control of the propellant (5).

Additionally, the method allows a constant reading of the motor (11) in order to allow the perception of the rotation continuity, aiming at identifying the operation outage due to the entry of strange bodies in the pump (10) or to the loss of synchronism of the pump (10), thus, identifying if the pump (10) is operating correctly.

This invention is not limited to the representations mentioned or illustrated here, and it has to be understood in its wide scope. Many changes and other representations of the invention will come in mind of the one adept to the technique to which this invention belongs, having the benefit of the precept presented at previous descriptions and attached drawings. Further, it has to be understood that the invention is not limited to the revealed specific shape, and that the changes and other shapes are understood as enclosed within the scope of the attached claims. Although specific terms are nominated here, they are only used in a generic and descriptive form and not with a limiting purpose.