JP7425659B2 - Refrigerator - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies.Sold to the customers listed in the list of sales customers (delivery customers) between February 4, 2020 and March 31, 2020.

The present invention relates to a technology for detecting deterioration of an internal fan before it completely fails in a refrigerator equipped with an internal fan that is PWM controlled.

Pulse width modulation is well known as one of the methods for controlling the rotational speed of a motor. In pulse width modulation control, or PWM control, the voltage applied to the motor is pulsed on and off at regular intervals, and the proportion of on time in one cycle, that is, the duty ratio, is varied to increase or decrease the motor. Control to desired rotation speed. In the cold air forced circulation type refrigerator to which the present invention is directed, it is well known to perform PWM control on the fan motor of the internal fan, and this is disclosed in, for example, Patent Document 1.

Further, Patent Document 2 discloses a lifespan determination device that can detect deterioration when a PWM-controlled fan motor deteriorates due to factors such as aging. Here, a reference PWM value (reference duty ratio: 50%, for example) and a reference rotation speed of the fan motor (for example, 1000 rpm) corresponding to this value are stored in advance in the storage section. The life determination device actually drives the fan motor at a reference PWM value, measures the number of rotations when the rotation becomes stable, that is, the actual number of rotations, and compares this with the reference number of rotations. If the rotation difference, which is the value obtained by subtracting the actual rotation speed from the reference rotation speed, is less than or equal to a predetermined value, the fan motor is determined to be normal, and conversely, if the rotation difference is larger than the predetermined value, the fan motor is It determines that the product is nearing the end of its lifespan and displays a warning. If this lifespan determination device is applied to the internal fan of a refrigerator, maintenance personnel will be able to detect the progress of deterioration of the internal fan before the internal fan completely breaks down and causes insufficient cooling within the refrigerator. We can inform you so that appropriate measures such as replacement or repair can be taken.

Japanese Patent Application Publication No. 2008-70012 Japanese Patent Application Publication No. 2001-298989

The life determination device disclosed in Patent Document 2 determines the state of a fan motor based on the rotational speed when the fan motor is actually driven at a reference PWM value. In other words, in order to detect the progression of deterioration of the fan motor at an early stage using the lifespan determination device of Patent Document 2, it is necessary to periodically control the fan motor to drive it at a reference PWM value, in addition to the normal control of the fan motor. Therefore, the control flow of the fan motor may become complicated.

An object of the present invention is to detect the progress of deterioration of a refrigerator at an early stage without complicating the control flow of the fan motor in a refrigerator equipped with a PWM-controlled internal fan.

The refrigerator according to the present invention includes a cooler 4 that cools the air in the refrigerator interior 3, an interior fan 6 that circulates the air, a defrosting means 5 for defrosting the cooler 4, and an interior fan. A motor control unit 20 that controls the rotation speed of a fan motor 7 that is a drive source of the fan motor 6 is provided. The motor control unit 20 includes a drive unit 24 that applies a pulse voltage to the fan motor 7, a speed command unit 22 that outputs a target value of the rotation speed of the fan motor 7, and a measurement unit that measures the actual rotation speed of the fan motor 7. The duty ratio of the pulse voltage is set based on the target value output from the speed measurement section 23 and the speed command section 22 and the measured value measured by the speed measurement section 23, and the set value is output to the drive section 24. A PWM command unit 21 that performs the operation, a storage unit 25 that stores the normal value of the duty ratio of the pulse voltage, and a set value of the duty ratio outputted from the PWM command unit 21 at a predetermined timing during the cooling operation is acquired, a determination unit 26 that determines the degree of deterioration of the fan motor 7 by comparing the set value with a normal value stored in the storage unit 25, and the timing of determination by the determination unit 26 is determined by the defrosting means. This is the point in time when a predetermined measurement start time has elapsed since the cooling operation was restarted after the defrosting operation including the heating of the cooler 4 by No. 5 was completed .

The set value of the duty ratio of the pulse voltage output from the PWM command unit 21 at the time when the measurement start time has elapsed after the cooling operation is restarted after the first defrosting operation is completed after the cooling chamber is started. is stored in the storage unit 25 as a normal value.

In the refrigerator according to the present invention, the state of the fan motor 7 is determined based on the duty ratio of the pulse voltage applied to the fan motor 7 of the internal fan 6. Specifically, at a predetermined timing during the cooling operation, the set value of the duty ratio outputted from the PWM command unit 21 is acquired, and the set value is compared with the normal value stored in the storage unit 25. Accordingly, the degree of deterioration of the fan motor 7 is determined. According to this, the degree of deterioration of the fan motor 7 can be determined while performing normal cooling operation, and special control of the fan motor 7 for this determination can be made unnecessary. That is, according to the present invention, the progress of deterioration of the fan motor 7 can be detected at an early stage without complicating the control flow of the fan motor 7.

Here, the reason why the state of the fan motor 7 can be determined based on the duty ratio of the pulse voltage will be explained. If the fan motor 7 deteriorates and becomes difficult to rotate, for example, compared to the initial stage of operation, the fan motor 7 measured by the speed measurement unit 23 may The actual rotation speed of 7 is lower than the target rotation speed corresponding to the normal value. Therefore, the PWM command unit 21 upwardly adjusts the duty ratio of the pulse voltage in order to bring the measured value of the rotation speed closer to the target value. This upward correction is repeated until the measured value reaches the target value. In other words, the more the fan motor 7 deteriorates, the higher the duty ratio set by the PWM command section 21 becomes, and the greater the deviation from the normal value stored in the storage section 25 becomes. In the present invention, this phenomenon is utilized to determine the degree of deterioration of the fan motor 7.

The timing of the determination by the determining unit 26 can be set at the time when the measurement start time (for example, 5 minutes) has elapsed after the cooling operation is restarted after the defrosting operation is finished. According to this, the determination section 26 can perform each determination under the same condition that there is no frost on the cooler 4, so that the degree of deterioration of the fan motor 7 can be determined with high accuracy at all times.

After the first defrosting operation is completed after the cooling chamber is started, and when the measurement start time has elapsed after the cooling operation is restarted, the set value of the duty ratio of the pulse voltage output from the PWM command unit 21 is set. , can be stored in the storage unit 25 as a normal value. According to this, it is possible to set a normal value that reflects the installation environment there, the load situation inside the refrigerator 3, etc. at each shipping destination of the refrigerator. By using the normal value set in this way, the degree of deterioration of the fan motor 7 can be determined with higher accuracy than when the normal value is uniformly set at the time of factory shipment of the refrigerator.

FIG. 2 is a block diagram showing a motor control section of the refrigerator according to the embodiment of the present invention. It is a longitudinal cross-sectional view showing the schematic structure of the main part of the refrigerator. It is a block diagram showing the whole control system of a refrigerator. It is a timing chart showing the relationship between the driving state of each device and the temperature inside the refrigerator. 3 is a flowchart showing a procedure for determining the state of a fan motor.

(Example) An example of a refrigerator according to the present invention is shown in FIGS. 1 to 5. In FIG. 2, the refrigerator includes a rectangular parallelepiped-shaped insulating box 1 having an opening on the front, and an insulating door 2 that opens and closes the opening. At the top, there are a cooler 4 for cooling the air inside the refrigerator 3, a defrosting heater (defrosting means) 5 for defrosting the cooler 4, and an interior fan 6 for circulating the air inside the refrigerator 3. It is provided. The internal fan 6 is an axial fan whose driving source is a fan motor 7 consisting of a DC motor.

The cooler 4 constitutes a refrigeration cycle together with a compressor 11 and a condenser 12 installed in a machine room 10 outside the refrigerator. When the compressor 11 is in operation, that is, in a cooling operation, the cooler 4 is supplied with cooled low-temperature, low-pressure refrigerant liquid via the condenser 12 and an expansion valve (not shown), and the cooled refrigerant liquid is supplied to the refrigerator 3 that passes through the cooler 4. air is cooled by heat exchange. An internal temperature sensor 8 is arranged between the internal fan 6 and the cooler 4 to detect the temperature of the internal chamber 3 (the temperature of the air before it passes through the cooler 4 and is cooled). Reference numeral 13 is a cooling fan for air cooling the compressor 11 and condenser 12.

A control unit 15 (see FIG. 3) that controls the entire refrigerator mainly controls the compressor 11 on and off to maintain the refrigerator interior temperature D detected by the refrigerator interior temperature sensor 8 at the set temperature D0. Specifically, as shown in the timing chart of FIG. 4, a set temperature range of (D0±α)°C centered around the set temperature D0 is provided, and the upper threshold of the temperature range, that is, (D0+α)°C, is set when the compressor The cooling start temperature Don at which the compressor 11 starts to be driven is defined as the cooling start temperature Don, and the lower threshold value of the temperature range, that is (D0-α)° C., is defined as the cooling stop temperature Doff at which the drive of the compressor 11 is stopped. The internal fan 6 (fan motor 7) is driven at high speed when the compressor 11 is driven, and is driven at low speed when the compressor 11 is stopped. In other words, the control unit 15 alternately performs a cooling operation in which the compressor 11 and the internal fan 6 are driven simultaneously, and a blowing operation in which only the internal fan 6 is driven, to keep the internal temperature D within the set temperature range. to be maintained. Note that the cooling fan 13 is controlled to be turned on and off in conjunction with the compressor 11. The same applies during the defrosting operation which will be explained next.

Further, the control unit 15 starts energizing the defrosting heater 5, that is, starts defrosting operation, at regular timing or at a timing when a predetermined amount of frost formation on the cooler 4 is detected. During the defrosting operation, in addition to the compressor 11, the internal fan 6 is also controlled to stop. When the defrosting operation is performed, the internal temperature D rises above the cooling start temperature Don, so the required time T2 of the cooling operation performed after the end of the defrosting operation is longer than that of the normal cooling operation (after the end of the ventilation operation). It is longer than the required time T1. Note that the control unit 15 does not restart the cooling operation immediately after the power supply to the defrosting heater 5 ends, but waits for several minutes to drain water from the cooler 4 and then resumes the cooling operation. In this embodiment, this draining time is also defined as part of the defrosting operation.

The motor control unit 20, which is a part of the control unit 15, drives the fan motor 7 at high speed (2000 rpm in this embodiment) during cooling operation, and drives the fan motor 7 at low speed (1000 rpm in this embodiment) during blowing operation. The duty ratio of the pulsed voltage applied to the fan motor 7 is controlled so that the fan motor 7 is driven with This duty ratio is set by the PWM command section 21 shown in FIG. The PWM command unit 21 outputs a target value (2000 rpm or 1000 rpm) of the rotation speed of the fan motor 7 output from the speed command unit 22 and a measured value of the actual rotation speed of the fan motor 7 measured by the speed measurement unit 23. Set the duty ratio of the pulse voltage based on. That is, the duty ratio of the pulse voltage is set by feedback control. The set duty ratio is output to the drive unit 24, and the drive unit 24 generates a pulse voltage of the duty ratio by switching control, and applies it to the fan motor 7.

In addition to the above-mentioned PWM command section 21, speed command section 22, speed measurement section 23, and drive section 24, the motor control section 20 includes a storage section 25 that stores various information. The information stored in the storage unit 25 includes the normal value of the duty ratio of the pulse voltage applied to the fan motor 7 during cooling operation (while the internal fan 6 is being driven at high speed), and the normal duty ratio centered around this normal value. Includes range. In this example, the normal range of the duty ratio is set to 70 to 130% (70% or more and 130% or less) of the normal value.

The normal value of this duty ratio can be uniformly set when the refrigerator is shipped from the factory, but in this example, the actual duty ratio when the refrigerator is started at the shipping destination is set as the normal value. I set it. Specifically, after the first defrosting operation after the cooling warehouse is started, the PWM command unit The set value of the duty ratio of the pulse voltage outputted from 21 is stored in the storage unit 25 as a normal value (steps S1 to S4 in the flowchart of FIG. 5). This measurement start time is set to be sufficiently shorter than the required time T2 for the cooling operation after the defrosting operation shown in FIG. 4. Therefore, at the time when the measurement start time has elapsed, the refrigerator is always in continuous cooling operation (the internal fan 6 is operating at high speed). When the target rotational speed of the internal fan 6 at high speed is 2000 rpm, the normal value of the duty ratio is approximately 40%.

Furthermore, the motor control section 20 includes a determination section 26 that determines the degree of deterioration of the fan motor 7. After the second and subsequent defrosting operations are completed after starting the cooling chamber, the determination unit 26 determines whether the measurement start time (5 minutes) has elapsed at the same timing as the previous normal value setting, that is, after the resumption of the cooling operation. , obtains the set value of the duty ratio output from the PWM command section 21, and compares the set value with the normal range stored in the storage section 25 (steps S5 to S8 in the flowchart of FIG. 5). If the obtained setting value is within the normal range, it is determined that the degree of deterioration of the fan motor 7 is light, that is, normal; on the other hand, if it is not within the normal range, the deterioration of the fan motor 7 is determined to be such that it cannot be overlooked. It is determined that the vehicle has progressed to that point, and the notification means 30, such as a buzzer or a lamp, is activated (step S9). Thereby, it is possible to notify the user, maintenance personnel, etc. of the deterioration of the fan motor 7, and prompt them to take appropriate measures such as replacement or repair.

Here, the reason why the state of the fan motor 7 can be determined based on the duty ratio of the pulse voltage will be explained. If the fan motor 7 deteriorates and becomes difficult to rotate, for example, compared to the initial stage of operation, the fan motor 7 measured by the speed measurement unit 23 may The actual rotation speed of No. 7 is lower than the target rotation speed (2000 rpm in this embodiment) corresponding to the normal value. Therefore, the PWM command unit 21 upwardly adjusts the duty ratio of the pulse voltage in order to bring the measured value of the rotation speed closer to the target value. This upward correction is repeated until the measured value reaches the target value. In other words, the more the fan motor 7 deteriorates, the higher the duty ratio set by the PWM command section 21 becomes, and the greater the deviation from the normal value stored in the storage section 25 becomes. In this embodiment, the allowable range (normal range) of this deviation is set within 30% of the normal value, and if this is exceeded, it is determined that the fan motor 7 is approaching the end of its life.

As described above, in the refrigerator according to the present embodiment, the duty ratio of the pulse voltage set by the PWM command unit 21 is acquired during the cooling operation, and this is compared with the normal value stored in the storage unit 25. By doing so, the degree of deterioration of the fan motor 7 is determined. According to this, the degree of deterioration of the fan motor 7 can be determined while performing normal cooling operation, and special control of the fan motor 7 for this determination can be made unnecessary. In other words, according to this embodiment, the progress of deterioration of the fan motor 7 can be detected at an early stage without complicating the control flow of the fan motor 7.

Further, in this embodiment, the timing of the determination by the determination unit 26 is set to the time when the measurement start time has elapsed after the cooling operation was restarted after the defrosting operation ended. According to this, the determination unit 26 can perform each determination under the same condition that there is no frost on the cooler 4, so that the degree of deterioration of the fan motor 7 can be determined with high accuracy at all times. Furthermore, in this embodiment, after the first defrosting operation is completed after the refrigerator is started, and when the measurement start time has elapsed after the cooling operation is restarted, the pulse voltage output from the PWM command unit 21 is The set value of the duty ratio is stored in the storage unit 25 as a normal value. According to this, it is possible to set a normal value that reflects the installation environment there, the load situation inside the refrigerator 3, etc. at each shipping destination of the refrigerator. By using the normal value set in this way, the degree of deterioration of the fan motor 7 can be determined with higher accuracy than when the normal value is uniformly set at the time of factory shipment of the refrigerator.

In the embodiment described above, the defrosting means 5 is constituted by a heater, but instead of this, for example, hot gas directly supplied from the compressor 11 to the cooler 4 may be used. The present invention can also be applied to showcases in which foods are displayed in a refrigerated or frozen state.

3 Inside the refrigerator 4 Cooler 5 Defrosting means (defrosting heater)
6 Internal fan 7 Fan motor 20 Motor control section 21 PWM command section 22 Speed command section 23 Speed measurement section 24 Drive section 25 Storage section 26 Judgment section

Claims (2)

A cooler (4) that cools the air inside the refrigerator (3), an interior fan (6) that circulates the air, a defrosting means (5) for defrosting the cooler (4), It is equipped with a motor control section (20) that controls the rotation speed of a fan motor (7) that is a drive source of the inner fan (6),
The motor control unit (20)
a drive unit (24) that applies a pulsed voltage to the fan motor (7);
a speed command section (22) that outputs a target value of the rotation speed of the fan motor (7);
a speed measurement unit (23) that measures the actual rotation speed of the fan motor (7);
Based on the target value output from the speed command unit (22) and the measured value measured by the speed measurement unit (23), the duty ratio of the pulse voltage is set, and the set value is output to the drive unit (24). A PWM command unit (21),
a storage unit (25) that stores a normal value of the duty ratio of the pulse voltage;
By acquiring the set value of the duty ratio output from the PWM command unit (21) at a predetermined timing during cooling operation, and comparing the set value with the normal value stored in the storage unit (25). , a determination unit (26) that determines the degree of deterioration of the fan motor (7);
Equipped with
The timing of the determination by the determination unit (26) is when a predetermined measurement start time has elapsed after the cooling operation is restarted after the defrosting operation including heating of the cooler (4) by the defrosting means (5) is completed. A refrigerator characterized by : After the first defrosting operation is completed after the cooling chamber is started, and the measurement start time has elapsed after the cooling operation is restarted, the duty ratio of the pulse voltage output from the PWM command unit (21) is determined. The refrigerator according to claim 1 , wherein the set value is stored in the storage unit (25) as a normal value .

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