JP2019027724A - refrigerator - Google Patents

Abstract

To provide a refrigerator that includes a highly reliable low-pressure storage chamber at low cost.SOLUTION: A refrigerator includes a low-pressure chamber 6 and decompression means for decompressing the low-pressure chamber 6, and uses a vacuum pump 7 not having pressure detection means, as the decompression means. The vacuum pump 7 includes a pump mechanism part and a DC motor for driving the pump mechanism part, and controls the vacuum pump 7 based on a current flowing through the DC motor.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a refrigerator.

  A conventional refrigerator is disclosed in JP 2009-36440 A (Patent Document 1). This refrigerator is provided with a decompression storage chamber, and this decompression storage chamber is installed in another storage chamber to be cooled, and is decompressed by sucking air with a vacuum pump. Thereby, the oxidation of a food can be suppressed and the freshness performance of the food when stored for a long time can be improved. In addition, a pressure switch is used as a means for detecting the air pressure in the decompression storage chamber. When the detected pressure is higher than the specified pressure, the vacuum pump is operated. When the detected pressure is lower, the vacuum pump is stopped and the power is reduced by intermittent operation. doing.

JP 2009-36440 A

  However, the conventional example described above has the following problems.

  In Patent Document 1, since ON / OFF of the operation of the vacuum pump is controlled by a pressure switch, as shown in FIG. 5 of Patent Document 1, in addition to the decompression storage chamber (low pressure chamber), a pressure switch is provided in the vacuum pump. It is necessary to form a sealed chamber. As described above, when a plurality of sealed spaces are provided, the possibility of air leakage increases accordingly. In addition, the provision of a pressure switch leads to an increase in cost.

  An object of the present invention is to realize cost reduction while improving reliability in a refrigerator provided with a decompression storage chamber.

  The present invention is a refrigerator provided with a storage chamber and a decompression means for decompressing the storage chamber, using a vacuum pump having no pressure detection means as the decompression means, the vacuum pump comprising: a pump mechanism section; And a DC motor that drives the pump mechanism, and controls the vacuum pump based on a current flowing through the DC motor.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerator provided with the reliable and low-cost decompression storage room can be provided.

It is a front view of the refrigerator of one embodiment of the present invention. It is a front view of the refrigerator compartment part of the refrigerator of FIG. It is a cross-sectional perspective view of the lowest space part of the refrigerator compartment of FIG. It is a perspective view of the low pressure chamber of the refrigerator compartment of FIG. It is the figure which showed simply the connection of a vacuum pump, a conduit | pipe, and a low pressure chamber. It is a control block diagram in this embodiment. It is a figure which shows the pressure reduction performance of a vacuum pump. FIG. 3 is a basic control time chart during a pressure reducing operation in the first embodiment. FIG. 3 is a basic control flowchart at the time of a pressure reducing operation in the first embodiment. FIG. 10 is a basic control time chart during a pressure reducing operation in the second embodiment. FIG. 10 is a basic control flowchart in the pressure reducing operation in the second embodiment. It is a figure which shows transition of the current signal at the time of setting 4th predetermined time longer than 50% in Embodiment 2. FIG. It is a figure which shows transition of the current signal at the time of setting the 4th predetermined time to 50% or less in Embodiment 2. FIG. It is a figure which shows the characteristic of the direct-current motor in Embodiment 3. FIG. 10 is a basic control time chart during a pressure reducing operation in the third embodiment. FIG. 9 is a basic control flowchart at the time of a pressure reducing operation in the third embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a front view of the refrigerator of the present embodiment. The refrigerator is constructed and arranged in the refrigerator compartment 2, the ice making compartment 3, the freezer compartment 4, and the vegetable compartment 5 from the top. The refrigerator compartment 2 and the vegetable compartment 5 are storage compartments in a refrigerated temperature zone, and the ice making compartment 3 and the freezer compartment 4 are storage compartments in a freezing temperature zone of 0 ° C. or less (for example, a temperature zone of about −20 ° C. to −18 ° C.). It is. Reference numeral 13 denotes an operation panel which is composed of a display LED 13a (not shown) and an operation switch (not shown).

  FIG. 2 is a front view of the inside of the refrigerator compartment 2 of FIG. Reference numeral 8 denotes a refrigeration room door switch that detects opening and closing of the refrigeration room door 2a that closes the opening of the refrigeration room 2, and a low pressure room 6 that is a storage room is disposed at the lowermost stage of the refrigeration room 2. Here, the low pressure chamber refers to a chamber that can be depressurized from 0 kPa · G (atmospheric pressure) to less than atmospheric pressure by a depressurizing means (for example, a vacuum pump).

  FIG. 3 is a perspective view of the lowermost step portion of the refrigerator compartment 2 in FIG. 2, and FIG. 4 is a perspective view of the low pressure chamber 6. The low pressure chamber 6 has a low pressure chamber door 6a for opening / closing the food intake / outlet opening on the front surface, and a low pressure chamber door switch 9 detects opening / closing of the low pressure chamber door 6a. Reference numeral 7 denotes a vacuum pump, which is an operation / configuration in which the vacuum pump 7 and the low pressure chamber 6 are connected by a conduit 7a, and the air in the low pressure chamber 6 is sucked by the vacuum pump 7 through the conduit 7a. FIG. 5 is a diagram simply showing the connection from the vacuum pump 7 to the low pressure chamber 6. As shown in FIG. 5, the vacuum pump 7 is electrically connected to the inside of the low pressure chamber 6 through a conduit 7a.

(First embodiment)
In the above configuration, a first embodiment will be described in which the pressure in the low pressure chamber 6 is reduced while suppressing excessive vacuum pump ON without using a pressure switch.

  FIG. 6 is a control block diagram. Reference numeral 10 denotes a refrigerator temperature sensor for detecting the temperature in the refrigerator compartment 2, reference numeral 12 denotes a microcomputer mounted on a refrigerator control board (not shown), reference numeral 13a denotes a display LED incorporated in the operation panel 13, reference numeral 7b. Is a DC motor that drives the vacuum pump 7. The detection signals of the refrigerator compartment door switch 8, the low pressure compartment door switch 9, and the refrigerator compartment temperature sensor 10 are input to the microcomputer 12, and output signals are output to the display LED 13a and the vacuum pump 7 (DC motor 7b) based on the control specifications described later. It is a configuration. The current signal 7c is a signal representing the motor current of the DC motor 7b, and the signal is fed back to the microcomputer 12. Further, the current signal 7c fed back to the microcomputer 12 is amplified by the current amplifier circuit 11 mounted on the refrigerator control board, so that a minute current increase / decrease can be detected more accurately.

  Next, FIG. 7 shows the pressure state inside the low-pressure chamber 6 and the state of the current signal 7c when the vacuum pump 7 is continuously operated. The horizontal axis indicates the operation time after the vacuum pump 7 is started, and the vertical axis indicates the pressure in the low-pressure chamber 6 and the level of the current signal 7c. In this specification, the pressure value is a gauge pressure, and the unit is represented by kPa · G. Therefore, atmospheric pressure = 0 kPa · G, and a negative value at a lower pressure than that.

  When the vacuum pump 7 was connected to the low pressure chamber 6 and operated, according to the experiments by the inventors, when the vacuum pump 7 was started to operate as shown in FIG. 7, the pressure gradually decreased with time. Here, the vacuum pump 7 in the present embodiment uses a pump whose decompression capacity does not fall below -30 kPa · G. By using such a pump, the volume of the low pressure chamber 6 is different, that is, the amount of air to be sucked is different, but when the same vacuum pump 7 is used, the smaller the volume, the faster the pressure decreases. However, in this embodiment, the pressure inside the low pressure chamber 6 is considered not to fall below -30 kPa · G.

  On the other hand, the current value of the current signal 7c increases as the pressure in the low-pressure chamber decreases. This phenomenon is due to the characteristics of the DC motor 7b used as the power source of the vacuum pump 7. Since the DC motor has a characteristic that the motor load and the motor current are proportional, the current value increases as the motor load increases as the atmospheric pressure in the low-pressure chamber decreases.

  When the pressure is below a certain pressure, the work of the pump mechanism is reduced (no pressure reduction), so the motor load is reduced and the motor current is reduced.

  In the refrigerator described above, the control specifications for detecting that the pressure in the low-pressure chamber 6 is equal to or lower than a predetermined pressure with a vacuum pump that does not have a switch for detecting pressure, and the flowchart shown in FIG. Will be described.

First, since the low-pressure chamber 6 is stored inside the refrigerator compartment 2, it is determined whether the vacuum pump 7 is turned on depending on whether the refrigerator compartment door 2a is opened or closed.
In the present embodiment, the vacuum pump is turned on only when the time from when the refrigerator door 2a is opened (S001) to when it is closed (S002) is 3 seconds or more. (S003). If the open / close time is less than 3 s, the vacuum pump remains off (S004), and if it is 3 s or longer, the vacuum pump 7 is turned on (S005).

  Here, the basis for the door opening time of 3 seconds, which is a condition for operating the vacuum pump, will be described. To open and close the low-pressure chamber door 6a of the low-pressure chamber 6, open the refrigerator compartment door 2a (in the case of a double door French door), open the low-pressure chamber door 6a and open the tray. A series of procedures of drawing out, putting in and out food, returning the tray, closing the low pressure chamber door 6a, and closing the refrigerator compartment door 2a is required, which is longer than the case where the low pressure chamber 6 is not used.

  Therefore, it was confirmed by an experiment by 21 people how much time it took concretely using a refrigerator whose refrigerator door had a French door. Then, the average time is about 7 seconds. As a result of considering variation, if the vacuum pump is operated when the opening time of the refrigerator door is 3 seconds, a refrigerator room other than the low pressure chamber 6 is used. It has been found that it is possible to prevent the vacuum pump from being operated in vain.

Whether the refrigerator door is opened or closed while the vacuum pump is on is detected (S006). If the door is opened or closed, the low pressure detection control is terminated and the vacuum pump is turned on until the third predetermined time (t3) after the refrigerator door is closed. The operation ends (S007).
Here, the third predetermined time (t3) is a time for setting the pressure inside the low pressure chamber 6 between -15 and -20 kPa · G, and in this embodiment, a value such as 150 s is set. doing. The third predetermined time (t3) needs to be changed depending on the volume of the low-pressure chamber 6, for example, 150 s for 20L and 75s for 10L.

  When the first predetermined time (t1) has passed without the refrigerator compartment door being opened or closed, the first current value (I1) at that time is measured (S008). As shown in the chime chart of FIG. 8, since the direct current motor 7b is much larger than the normal current immediately after being turned on and a current (rush current) flows, the first predetermined time after the vacuum pump 7 is turned on in order not to detect this accidentally. The first current value (I1) is measured after (t1) has elapsed. Since the inrush current is several ms to several hundred ms as a guide, in the present embodiment, the first predetermined time is 10 s.

Thereafter, when the refrigerator compartment door 2a is not opened or closed until the second predetermined time (t2), the second current value (I2) is measured (S011). When the refrigerator compartment door 2a is opened and closed before the second predetermined time (t2) elapses, the low-pressure detection control is finished, and after the refrigerator door is closed, the vacuum pump is turned on until the third predetermined time (t3), and the operation is finished. (S010)
Here, the second predetermined time (t2) is set to be shorter than the third predetermined time (t3), so that if the pressure in the low pressure chamber 6 is already low and no further pressure reduction is necessary, an excessive vacuum is applied. The operation of the pump 7 can be suppressed.

  As described above, since the current value of the DC motor 7b increases / decreases depending on the motor load, it is preferable that the second predetermined time is as long as possible in order to secure a sufficient pressure change range. However, in order to suppress excessive ON of the vacuum pump 7, it is necessary to make the time as short as possible. In the present embodiment, the second predetermined time (t2) is set to 30 to 70% of the third predetermined time (t3). For example, in the case of a low pressure chamber capacity in which the third predetermined time (t3) is set to 150 s, the third predetermined time is set to 75 s.

The difference between the first current value (I1) and the second current value (I2) is calculated (S012), and the result (ΔI), 0 kPa · G (atmospheric pressure), and threshold value (X) for determining the low pressure Are compared (S013). When ΔI <X, the pressure in the low pressure chamber 6 is determined to be low, and the vacuum pump 7 is turned off. (S014). When ΔI ≧ X, it is determined that the pressure in the low pressure chamber 6 is 0 kPa · G (atmospheric pressure), and the vacuum pump 7 is kept ON until the third predetermined time (t3). (S015)
With the above control specifications, it is possible to estimate the pressure in the low pressure chamber 6 from the current of the DC motor 7b, and to suppress useless operation of the vacuum pump 7. Thereby, the reliable refrigerator which reduced the leak can be provided by discriminating the pressure in the low pressure chamber 6 without using the pressure switch. Note that the term “leak” here means that air flows into the sealed space through the gap between the sealed space due to a pressure difference between the decompressed sealed space and the sealed space in the sealed space of the decompression storage chamber or the vacuum pump.

(Second embodiment)
Next, a second embodiment will be described in which the pressure in the low pressure chamber 6 is reduced while suppressing excessive vacuum pump ON without using a pressure switch by simpler control than in the first embodiment. The component configuration is the same as in the first embodiment.

  A time chart in the second embodiment is shown in FIG. 10, and a flowchart is shown in FIG.

  First, the operations from S016 to S022 are the same as those from S01 to S07 described in the first embodiment.

  After the vacuum pump 7 is turned on (S020), when the operation is continued until the fourth predetermined time, the fourth current value (I4) at that time is measured (S023).

The first current value (I1) is compared with the low pressure determination value Y (S024). If I1 <Y, the pressure is determined to be low and the vacuum pump 7 is turned off (S025). If I1 ≧ Y, 0 kPa · G (large Pressure) and the vacuum pump 7 is kept ON until the third predetermined time (t3) (S026).
Here, in the refrigerator according to the present embodiment, the fourth predetermined time is set to a time within a range of 50% or less of the third predetermined time. As described above, the motor current of the DC motor 7b used as the power source of the vacuum pump 7 increases in proportion to the increase of the motor load. When the fourth predetermined time is set to be longer than 50% of the third predetermined time, the current increases even if the pressure reduction starts from 0 kPa · G (atmospheric pressure), and there is a clear difference from the case where the pressure is reduced from the low pressure. It is difficult to distinguish. FIG. 12 shows the transition of the current signal in this state. As shown in FIG. 12, when the vacuum pump is turned on from 0 kPa · G (atmospheric pressure), or when the low-pressure air vacuum pump is turned on, any fourth current value (I4) is larger than Y and cannot be discriminated. ing.

  On the other hand, when the fourth predetermined time is 50% or less of the third predetermined time, the fourth current value (I4) when the vacuum pump is turned on from 0 kPa · G (atmospheric pressure) is lower than the low pressure judgment value Y. , 0 kPa · G (atmospheric pressure) and low pressure can be discriminated. The transition of the current signal in this state is shown in FIG.

  With the above control, it is possible to provide a refrigerator that can determine the pressure in the low pressure chamber 6 without using a pressure switch with a simpler control configuration.

(Third embodiment)
Next, a method for determining whether the pressure in the low pressure chamber 6 is 0 kPa · G (atmospheric pressure) or low pressure based on the rotational speed of the DC motor 7b will be described.

  First, FIG. 14 shows a characteristic diagram of a general DC motor. The vertical axis represents the current [I] and the rotational speed [min ^ -1], and the horizontal axis represents the torque [mNm]. The torque represents the weight of the load applied to the motor.

  According to the characteristic diagram shown in FIG. 14, the current [I] increases in proportion to the increase in torque, and the rotational speed [min ^ -1] has a characteristic that causes a phenomenon in proportion.

  In the first and second embodiments, the low-pressure detection method using the current [I] has been described. In the third embodiment, the low-pressure detection method based on the rotational speed [min ^ -1]. explain.

  FIG. 15 shows a time chart of low-pressure detection control using the rotational speed [min ^ −1], and FIG. 16 shows a flowchart. The operation will be described below with reference to FIGS.

  The control flow is the same as S001 to S015 shown in the first embodiment, and the detection target is changed from current to rotation speed.

  As in the first embodiment, the first rotation speed (N1) and the second rotation speed (N2) are measured, and the difference ΔN is calculated (S038). If ΔN <Z, the pressure in the low pressure chamber 6 is calculated. Is determined to be low pressure, and the vacuum pump 7 is turned off. (S014) When ΔN ≧ Z, the pressure in the low pressure chamber 6 is determined to be 0 kPa · G (atmospheric pressure), and the vacuum pump 7 is kept ON until the third predetermined time (t3). (S041) With the above operation, it is possible to estimate the pressure in the low pressure chamber 6 from the rotational speed of the DC motor 7b, and to suppress the useless operation of the vacuum pump 7. Thereby, the reliable refrigerator which reduced the leak can be provided by discriminating the pressure in the low pressure chamber 6 without using the pressure switch.

  The means for detecting the rotational speed of the DC motor 7b can be obtained from the frequency of the motor current in the case of a DC brush motor.

  Some DC brushless motors output a rotation speed signal (FG signal) on a built-in drive board, and thus the rotation speed can be detected.

  In any motor, when the low pressure is detected from the rotational speed, the current amplification circuit 11 can be dispensed with, so that it is possible to realize a cheaper low pressure detection specification.

2 cold room 2a cold room door 3 ice making room 4 freezer room 5 vegetable room 6 low pressure room 6a low pressure room door 7 vacuum pump 7a conduit 7b DC motor 7c current signal 11 current amplification circuit 8 cold room door switch 9 low pressure room door switch 10 refrigeration Room temperature sensor 11 Current amplification circuit 12 Microcomputer 13 Operation panel 13a Display LED

Claims (6)

A refrigerator equipped with a storage room and a decompression means for decompressing the storage room,
As the pressure reducing means, a vacuum pump having no pressure detecting means is used,
The vacuum pump has a pump mechanism and a direct current motor that drives the pump mechanism,
A refrigerator that controls the vacuum pump based on a current flowing through the DC motor. In claim 1,
Detecting a first current value of the DC motor after a first predetermined time has elapsed since turning on the vacuum pump;
Furthermore, after the second predetermined time has elapsed, the second current value of the DC motor is detected,
A refrigerator that determines whether or not to continue to turn on the vacuum pump based on the difference between the first current value and the second current value. In claim 2,
If the difference between the first current value and the second current value is greater than a predetermined value, the vacuum pump is kept on,
The refrigerator characterized by turning off the vacuum pump when the difference between the first current value and the second current value is smaller than a predetermined value. In claim 1,
A first current value of the DC motor is detected after elapse of a first predetermined time from turning on the vacuum pump;
A refrigerator that determines whether or not to continue to turn on the vacuum pump based on the magnitude of the first current value. A refrigerator equipped with a storage room and a decompression means for decompressing the storage room,
As the pressure reducing means, a vacuum pump having no pressure detecting means is used,
The vacuum pump has a pump mechanism and a direct current motor that drives the pump mechanism,
A refrigerator that controls the vacuum pump based on the rotational speed of the DC motor. A refrigerator equipped with a storage room and a decompression means for decompressing the storage room,
As the pressure reducing means, a vacuum pump having no pressure detecting means is used,
The vacuum pump has a pump mechanism and a direct current motor that drives the pump mechanism,
The refrigerator characterized in that, even in a state where the storage chamber is depressurized, the vacuum pump is once turned ON from OFF.

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