Washing machine

Abstract

Provided is a washing machine capable of further improving the accuracy of sensing the amount of laundry by rotating a pulsator. The washing machine of the embodiment includes a rotating tub, a pulsator disposed at the inner bottom of the rotating tub, a motor that rotates the pulsator, and a control unit that drives the motor using a torque current to rotate the pulsator and thereby perform sensing of the amount of laundry in the rotating tub. The control unit measures the rotational speed of the motor during a period in which the pulsator is rotated in the forward direction and then idles, and then the pulsator is rotated in the reverse direction and then idles, when performing sensing of the amount of laundry. The torque current for rotating the pulsator is initially set to a first current that is relatively large, and then switched to a second current that is relatively small.

Description

Technical Field

[0001] Embodiments of the present invention relate to a washing machine that senses the amount of laundry placed into the drum. Background Technology

[0002] In so-called vertical washing machines with an impeller at the bottom of the drum, there exist washing machines that rotate the impeller when sensing the amount of laundry placed in the drum, and sense based on its rotational state. For example, Patent Document 1 discloses a washing machine that applies a drive voltage to a motor that drives the impeller to rotate, and senses the amount of laundry contained in the washing tub, i.e., the amount of fabric, based on the applied voltage that makes the rotational speed of the drive motor not limited to the load of laundry.

[0003] Existing technical documents

[0004] Patent documents

[0005] Japanese Patent Application Publication No. 2003-311077 Summary of the Invention

[0006] The problem that the invention will solve

[0007] However, in the control of applying a drive voltage to the motor, the output torque of the motor is not constant, so the accuracy of sensing the amount of fabric will be reduced.

[0008] Therefore, a washing machine is provided that can further improve the accuracy of sensing the amount of fabric by rotating the impeller.

[0009] Methods for solving problems

[0010] The washing machine of the embodiment includes: a rotating drum; an impeller disposed at the inner bottom of the rotating drum; a motor that rotates the impeller; and a control unit that drives the motor using torque current to rotate the impeller, thereby sensing the amount of fabric inside the rotating drum. When sensing the amount of fabric, the control unit measures the rotational speed of the motor during a period in which the impeller rotates in the forward direction and then idles, and then rotates the impeller in the reverse direction and then idles. The torque current during the period in which the impeller rotates is initially set to a relatively large first current, and then switched to a relatively small second current.

[0011] Invention Effects

[0012] The washing machine according to the present invention can further improve the accuracy of sensing the amount of fabric by rotating the impeller. Attached Figure Description

[0013] Figure 1 This is a longitudinal sectional side view schematically showing a portion of the configuration of a washing machine according to one embodiment.

[0014] Figure 2 This is a circuit diagram showing the electrical structure of a washing machine.

[0015] Figure 3 This is a block diagram representing the electrical structure of a washing machine.

[0016] Figure 4 This is a flowchart showing the processing of weight sensing control during forward rotation.

[0017] Figure 5 This is a flowchart illustrating the processing of weight sensing control during reversal.

[0018] Figure 6 It is a graph that shows the change in rotational speed under no-load conditions using waveforms.

[0019] Figure 7 The graph shows the change in rotational speed with a load of 4.5 kg.

[0020] Figure 8 This is a graph showing the change in the number of pulses measured based on weight, under the condition that the q-axis current is kept constant at 0.8A from the beginning and the same control is performed as in this embodiment.

[0021] Figure 9 This is a graph showing the change in the number of pulses measured based on weight under the control conditions of this embodiment.

[0022] Explanation of reference numerals in the attached figures

[0023] In the attached diagram, 7 represents the control circuit, 9 represents the speed sensor, 102 represents the rotating drum, 108 represents the impeller, and 113 represents the electric motor. Detailed Implementation

[0024] Hereinafter, an embodiment will be described with reference to the accompanying drawings. Figure 1 As shown, in this embodiment, the washing machine 100 has an open-topped, bottomed cylindrical water tank 102 elastically supported inside the outer casing 101 that forms its outer shape by an elastic suspension mechanism 103. Inside the water tank 102, an open-topped, bottomed cylindrical rotating drum 104 is rotatably provided. The rotating drum 104 can be removed and placed inside to hold laundry.

[0025] A reinforcing member 105 is provided at the bottom of the drum 104 to strengthen the bottom of the drum 104. The drum 104 is configured to rotate around a vertical axis and serves as a washing drum for washing clothes, a rinsing drum for rinsing clothes, and a dehydrating drum for dehydrating clothes. That is, the washing machine 100 is a so-called longitudinal axis type washing machine in which the rotation center axis of the drum 104 extends in a vertical direction.

[0026] The rotating drum 104 has multiple holes 106 on its peripheral wall. These holes 106 are interconnected, allowing for the passage of water and air. Additionally, in... Figure 1 Only a portion of the multiple holes 106 are shown. A balancing ring 107 made of synthetic resin, for example, containing a liquid such as brine, is installed on the upper part of the rotating drum 104. Inside the rotating drum 104, specifically at the inner bottom, a pulsator 108, for example, made of synthetic resin, is rotatably provided as a stirring element. A drainage path 109 is provided at the lower part of the water tank 102. A drain valve 110 is provided in the drainage path 109; when the drain valve 110 is opened, water in the water tank 102 is drained outside the machine. Additionally, an anti-air valve 111 for water level sensing is provided at the bottom of the water tank 102.

[0027] A drive mechanism 112 is provided at the center of the lower part of the water tank 102. The drive mechanism 112 includes a clutch mechanism 112a, which contains a motor 113 that drives the rotating drum 104 to rotate, and a clutch / reduction gear. During the washing or rinsing process, the drive mechanism 112 transmits rotational force to the impeller 108 via the clutch mechanism 112a. Therefore, during the washing or rinsing process, the rotating drum 104 is not driven to rotate; only the impeller 108 is driven to rotate. At this time, the impeller 108 is driven to rotate at 1 / 5 of its speed. Furthermore, during the spin-drying process, the drive mechanism 112 transmits the rotational force of the motor 113 to both the impeller 108 and the rotating drum 104 via the clutch mechanism 112a. Therefore, during the spin-drying process, the impeller 108 and the rotating drum 104 rotate together. At this time, the rotating drum 104 is driven to rotate without slowing down.

[0028] A top cover 114 is provided on the upper part of the outer casing 101. The top cover 114 has a folding cover 115 that can be opened and closed to allow the laundry inlet and outlet to be opened and closed. Additionally, a tub cover (not shown) is installed on the upper part of the water tank 102. An operation panel 116 is provided at the front of the top cover 114. A control unit 117 that controls the overall operation of the washing machine 100 is located inside the operation panel 116. A water supply mechanism 118 that supplies water from a water source to the water tank 102 is located at the rear inside the top cover 114. The water supply mechanism 118 includes a water supply valve (not shown) and a water supply path (not shown) connected to the water tank 102. The control unit 117 controls the water supply to the water tank 102 by controlling the opening and closing of the water supply valve.

[0029] Figure 2 This is a functional block diagram representing the drive control system of the electric motor 113. In this case, the control unit 117 includes a PWM control inverter, i.e., inverter circuit 1. PWM is short for Pulse Width Modulation. The inverter circuit 1 is constructed by connecting six IGBTs 2a to 2f as semiconductor switching elements in a three-phase bridge configuration, with flywheel diodes 3a to 3f connected between the collector and emitter of each IGBT 2a to 2f. The output terminals of each phase of the inverter circuit 1 are respectively connected to the motor windings 113u, 113v, and 113w of the electric motor 113. In this embodiment, the electric motor 113 is, for example, an external rotor type three-phase brushless DC motor.

[0030] The emitters of IGBTs 2d, 2e, and 2f on the lower arm side are grounded via a shunt resistor 4, which serves as a current sensing element. Furthermore, the common connection point between the emitters of IGBTs 2d, 2e, and 2f and the shunt resistor 4 is grounded via a resistor 5 and a capacitor 6. The common connection point of the resistor 5 and the capacitor 6 is connected to the A / D input terminal 2 of the control circuit 7 and to the input terminal of the overcurrent detection circuit 8. The overcurrent detection circuit 8 is constructed using a comparator, etc. The output signal of the overcurrent detection circuit 8 becomes an emergency stop signal based on overcurrent detection. When an emergency stop signal is input, the control circuit 7 stops the PWM signal output to the inverter circuit 1.

[0031] A speed sensor 9 for detecting the rotor speed is provided in the motor 113. The speed sensor 9 is a magnetic sensor, for example, composed of a Hall IC, and outputs a sensor signal for detecting the speed. The sensor signal output from the speed sensor 9 is input to the control circuit 7 via the NOT gate 10. The output terminal of the NOT gate 10 is grounded via the capacitor 11. In addition, as long as the speed sensor 9 is provided in at least one location, the control performed in this embodiment can be executed.

[0032] A drive power supply circuit 12 is connected to the input side of inverter circuit 1. Drive power supply circuit 12 uses a full-wave rectifier circuit 14 composed of a diode bridge and two capacitors 15a and 15b connected in series to perform voltage multiplication full-wave rectification on a 100V AC power supply 13, supplying approximately 280V DC voltage to inverter circuit 1. The output terminals of each phase of inverter circuit 1 are connected to the windings 113u, 113v, and 113w of each phase of motor 113. First power supply circuit 16 steps down the approximately 280V drive power supply supplied to inverter circuit 1 to generate 15V power, which is then supplied to drive circuit 17 and high-voltage driver circuit 19. Second power supply circuit 18 is a three-terminal regulator that steps down the aforementioned drive power supply to generate 5V control power, which is then supplied to control circuit 7, speed sensor 9, and third power supply circuit 20.

[0033] The high-voltage driver circuit 19 is configured to drive the IGBTs 2a to 2c on the upper arm side of the inverter circuit 1. The third power supply circuit 20 generates a 3.3V power supply from the aforementioned 5V and supplies this power to the overcurrent detection circuit 8. The A / D input terminal 2 of the control circuit 7 is pulled up to the 3.3V power supply using resistor element 21. A series circuit of resistor elements 22a and 22b is connected between the output terminal of the drive power supply circuit 12, the positive DC bus of the inverter circuit 1, and ground. The common connection point of both is connected to the A / D input terminal 1 of the control circuit 7.

[0034] The control circuit 7 detects the three-phase current flowing to the motor 113 based on the terminal voltage of the shunt resistor 4, and performs vector control to generate a PWM signal with a sinusoidal voltage rate in the upper and lower portions of the three phases. The control circuit 7 outputs the PWM signal to the gates of each IGBT 2a to 2f constituting the inverter circuit 1 via the drive circuit 17 and the high-voltage driver circuit 19. In the drive circuit 17, each input terminal used to input the PWM signal is pulled down to ground potential by the resistor 23.

[0035] In the above configuration, bootstrap capacitors 24d, 24e, and 24f are connected between the emitters of IGBTs 2d, 2e, and 2f on the lower arm side and the high-voltage driver circuit 19, respectively. In this configuration, the bootstrap capacitors 24d to 24f are charged with the switching action of IGBTs 2a to 2f, thereby generating the power supply voltage used by the high-voltage driver circuit 19 to drive the gates of IGBTs 2a to 2c on the upper arm side.

[0036] A series circuit of resistors 25a and 25b is connected between the W-phase output terminal of inverter circuit 1 and ground. The common connection point of resistors 25a and 25b is connected to the leakage current sensing input port of control circuit 7. Control circuit 7 senses the generation of leakage current by the voltage generated at the common connection point.

[0037] In this embodiment, the control circuit 7 functions as a current detection unit that detects the current flowing through the motor 113, and also functions as a control unit that performs vector control on the motor 113 based on the current detected by the current detection unit. In this case, the control circuit 7 controls the motor 113 so that the rotational speed of the motor 113 follows a desired target speed. The control circuit 7 performs predetermined sensing control based on sensor signals. Specifically, the control circuit 7 performs abnormal sensing control and weight sensing control as predetermined sensing control.

[0038] Abnormal sensing control includes, for example, sensing abnormalities such as leakage current or overcurrent. Weight sensing control, which is equivalent to fabric quantity sensing, is as follows: after the clothes are put into the drum 104, the rotation speed of the drum 104 is calculated based on the sensor signal when the impeller 108 rotates, and the amount of clothes is determined based on the calculated rotation speed.

[0039] Figure 3 This is a block diagram that roughly represents the electrical structure of the washing machine 1, centered on the control circuit 7. The control circuit 7, for example, is primarily composed of a microcomputer and has the function of controlling the overall operation of the washing machine. This control circuit 7 receives input signals from the operation input unit 33, water level sensor 34, safety switch 30, speed sensor 9, etc. Based on these input signals and a pre-existing control program, the control circuit 7 controls the motor 35, which switches between the display unit 32, water supply valve 118, motor 113, clutch mechanism 112a, or drain valve 110.

[0040] Next, refer to Figures 4 to 9 The function of this embodiment will be explained. Figure 4 as well as Figure 5 This is a flowchart illustrating the weight sensing control processing performed by control circuit 7. Figure 4 In the process of making the impeller 108 rotate forward, the control circuit 7 first positions the rotor for, for example, 0.2 seconds (F1), then sets the d-axis current Id in the vector control to, for example, 4A, and starts the forward rotation of the motor 113 by forced commutation (F2). Then, referring to the sensor signal of the speed sensor 9, the speed measurement begins (F3). Specifically, the number of pulses of the sensor signal output in pulse form is measured.

[0041] If the speed of motor 113 reaches 300 rpm or higher (F4; YES), the torque current, i.e., the q-axis current Iq, is set as the first current, for example, to 2A, and the current drive of motor 113 continues (F5). Then, if the speed of motor 113 reaches a threshold, i.e., 700 rpm or higher (F6; YES), the q-axis current Iq is changed as the second current, for example, to 0.8A. If this state continues for 0.6 seconds, the forward rotation of impeller 108 ends (F8; YES), and the power supply from inverter circuit 1 to motor 113 stops (F9). Afterward, if the rotation of motor 113 stops (F10; YES), the number of pulses of the sensor signal output by speed sensor 9 before that moment is stored (F11). Through the above, the processing during forward rotation ends, and the process moves to... Figure 5 The processing during reversal is shown.

[0042] The processing during reverse rotation is performed symmetrically to the processing during forward rotation. Figure 5 In the flowchart shown, the part corresponding to the forward rotation process is labeled "R" instead of "F". However, the end waiting time in step R8 is set to 0.4 seconds, which is shorter than the waiting time during forward rotation. In the above process, the control circuit 7 measures and stores the number of pulses of the sensor signal output during reverse rotation. Then, the number of pulses of the sensor signal measured during forward and reverse rotation are summed, and the weight of the laundry is inferred based on this sum.

[0043] The washing machine of this embodiment has a maximum load capacity of 7 kg for laundry. Figure 6 The waveform shows the change in rotational speed under no-load conditions. Figure 7 The waveform shown illustrates the change in rotational speed when the load is 4.5 kg. In the latter case, the rotational speed is 0 rpm before 2 seconds have elapsed.

[0044] Figure 8 This is the result of controlling the q-axis current Iq to be constant at 0.8A from the beginning, using the same control as in this embodiment. The straight line shown in the figure illustrates the ideal variation characteristics. If the weight of the bleached cloth provided as a load exceeds 2kg, the rotational speed hardly increases, resulting in a rotational lock-in state. In contrast, it can be seen that... Figure 9 In the case of the embodiment shown, it will not be as Figure 8 In that state of rotational locking, the number of pulses obtained by rotating the impeller 108 changes to a level that can distinguish up to 6 kg.

[0045] As described above, according to this embodiment, the control circuit 7 drives the motor 113, which rotates the impeller 108 disposed at the inner bottom of the rotating drum 104, through torque current to perform fabric quantity sensing within the rotating drum 104. Specifically, during fabric quantity sensing, the rotational speed of the motor 113 is measured during the period when the impeller 108 is rotated in the forward direction and then idled, and then the impeller 108 is rotated in the reverse direction and then idled again. Furthermore, the torque current during the period when the impeller 108 is rotated is initially set to a relatively large first current, and then switched to a relatively small second current.

[0046] Thus, by using torque current to drive the motor 113, the difference in rotational state corresponding to the amount of fabric becomes clear. Furthermore, initially using a relatively large first current prevents rotational lock-up, and then switching to a relatively small second current prevents excessive and continuous rotation of the motor 113. This allows for higher accuracy in sensing the amount of fabric and also prevents prolonged sensing time.

[0047] Furthermore, if the speed of the motor 113 reaches a threshold of 700 rpm, the control circuit 7 switches the torque current from the first current to the second current. Therefore, the torque current can be switched appropriately based on the speed, reliably preventing excessive continuous rotation. Moreover, since the control circuit 7 uses the q-axis current obtained by vector control of the DC brushless motor 113 to impart the torque current, the accuracy of torque control of the motor 113 can be improved, and the sensing accuracy of the fabric quantity can be enhanced.

[0048] (Other implementation methods)

[0049] Alternatively, shunt resistors 4 can be configured in each phase and the phase current can be detected individually.

[0050] The threshold is not limited to 700 rpm; it can be adjusted appropriately according to the individual design.

[0051] Furthermore, the speed at which the motor 113 is switched from forced commutation to torque current drive is not limited to 300 rpm.

[0052] The maximum load capacity of a washing machine is not limited to 7kg.

[0053] The specific values ​​of the first and second currents can be appropriately changed while maintaining the relationship between the two.

[0054] Alternatively, instead of using the speed sensor 9, the speed can be measured by sensing the current and induced voltage of the motor 113. For example, the speed can be measured by detecting the phase current during the driving of the motor 113, and by referring to the idle speed of the motor 113. Figure 2The leakage current sensing input shown can be used to detect the induced voltage and measure the rotational speed.

[0055] It is not necessary to use the q-axis current obtained through vector control as the torque current for control.

[0056] While several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are included in the scope of the invention as set forth in the claims and its equivalents.

Claims

1. A washing machine, characterized in that, have: Rotating bucket; The impeller is located at the bottom inside the rotating drum; An electric motor causes the impeller to rotate. The control unit uses torque current to drive the motor, causing the impeller to rotate, thereby sensing the amount of fabric inside the drum; and A speed sensor detects the speed of the motor. When performing the fabric weight sensing, the control unit measures the motor speed during the period when the impeller is rotated in the forward direction and then idled, and then rotated in the reverse direction and then idled again. It sums the number of pulses of the sensor signals measured by the speed sensor when the impeller is rotated in the forward direction and when the impeller is rotated in the reverse direction, and infers the weight of the laundry based on the sum of the number of pulses. During this period, the torque current is initially set to a relatively large first current, and then switched to a relatively small second current.

2. The washing machine according to claim 1, characterized in that, If the speed of the motor reaches a threshold, the control unit switches the torque current from the first current to the second current.

3. The washing machine according to claim 1 or 2, characterized in that, The motor is a DC brushless motor. The control unit uses the q-axis current obtained by vector control of the DC brushless motor to impart the torque current.

Images