JPH065151B2 - refrigerator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator in which the rotation speed of a compressor is changed based on a refrigeration load, and more particularly to a refrigerator using a rotation speed conversion device.

2. Description of the Related Art The amount of heat to be removed in a unit time by a cooling operation is called a refrigeration load in order to keep the air inside the refrigerator in a required state.
This refrigeration load can be roughly known by measuring the difference between the temperature inside the refrigerator and the temperature set value.

On the other hand, the refrigerating capacity of the refrigerator can be changed over a wide range by controlling the rotation speed of the compressor.

Therefore, it is possible to perform the minimum required cooling operation by changing the rotation speed of the compressor based on the refrigeration load, which can significantly improve the operation efficiency and greatly contribute to energy saving. Further, it is possible to always operate the compressor at the best rotation speed so that the temperature inside the refrigerator becomes the temperature set value, and it is possible to realize smooth temperature control inside the refrigerator.

Problems to be Solved by the Invention As described above, the conventional control system for changing the rotation speed of the compressor based on the refrigeration load has a voltage difference depending on the difference between the internal temperature and the temperature set value as shown in FIG. Since the control system is a so-called linear circuit that linearly changes the frequency to the compressor by using a frequency converter or the like and linearly controls the rotation speed of the compressor, the circuit is too complicated. Also, in performing the interlocking control with the internal temperature, the frequency setting or the error is large because the frequency is set by the analog signal, and therefore, the capacity error is large. Further, there is a drawback that the frequency fluctuates subtly even with a slight fluctuation in the internal temperature, and a fluctuating noise is generated. Furthermore, since the rotation speed of the compressor is controlled linearly, there is a possibility that it will be stable at any rotation speed from low rotation to high rotation.
There was a problem of causing noise and vibration due to resonance of the compressor and cooling system piping.

Therefore, the present invention has been made in view of the above points, and provides a refrigerator that simplifies the control circuit, suppresses fluctuations or errors in the rotational speed of the compressor, and suppresses noise discomfort and vibration. With the goal.

Means for Solving the Problems In order to achieve this object, the present invention compares the difference between the internal temperature and the temperature setting value with a preset threshold value at predetermined time intervals, and determines a predetermined value according to the result. A comparison control device is provided for sending a rotation speed setting signal to the rotation speed conversion device for sequentially increasing or decreasing the rotation speed of the compressor with time, or maintaining the current condition.

In the refrigerator of the present invention, since the comparison control device sends the rotation speed setting signal to the rotation speed conversion device at every predetermined time, the rotation speed of the compressor does not change until the predetermined time elapses. There is little fluctuation in the rotation speed of.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, an AC voltage 1'of a power supply 1 is converted into a DC 2'by a rectifier circuit 2 and applied to a rotation speed converter 3. In this rotation speed conversion device 3, a pulse width modulation signal generator 4 generates a pulse width modulation signal according to a motor rotation position of a compressor 6 in response to a digital signal, that is, a rotation speed setting signal a, and is amplified and switched by a power element 5. , And is converted into a variable voltage rotation position synchronizing pulse width modulation pressure 3 '. The output voltage of the rotation speed conversion device 3 is about 40 to 250.
It can be continuously changed in the range of V, whereby the rotation speed of the compressor 6 changes in the range of 1800 to 5400 rpm.

On the other hand, the digital signal applied to the rotation speed conversion device 3, that is, the rotation speed setting signal a is the output of the comparison control device 7, and the comparison control device 7 is operated by the operation switch 8 for quick freezing, thawing, etc. 9 and temperature setting device 10
, The microcomputer 11 performs logical operation processing based on a preset program,
The load 12 such as a fan motor is operated, and the rotation speed setting device 3 is supplied with the rotation speed setting signal a. Further, the internal configuration of the comparison control device 7 is the microcomputer 11
, And various timers are made in the microcomputer 11 based on the oscillation frequency input of the oscillator 13. The input of the internal temperature sensor 9 and the input of the temperature setter 10 are digital data sent from the memory 14 in which the preset program is stored to the data latch 16 through the central processing unit 15 for D / A conversion. The comparator 17 compares the reference voltage corresponding to the digital data with the comparator 18. The result of the comparison is returned to the central processing unit 15, and this operation is repeated by changing the digital data to obtain the data b corresponding to the internal temperature value and the data c corresponding to the temperature set value. The difference between the data b and the data c is calculated by the arithmetic processing unit 15
A temperature difference value can be obtained by performing a logical operation with. Next, data corresponding to the preset threshold value is stored in the memory 14
The temperature difference value is taken out from the central processing unit 15 and compared with the temperature difference value at every predetermined timer time. As a result, digital data corresponding to the rotation speed is sent to the rotation speed conversion device 3 through the data latch 19. Here, the memory 14, the central processing unit 15, and the data clutches 16 and 19 are configured by the one-chip microcomputer 11.

Since a digital signal is applied to the rotation speed conversion device 3, it is possible to provide a fine correspondence between the predetermined timer time and the compressor rotation speed. The explanation has been changed to make it easier to explain.

Hereinafter, an example of the correspondence between the difference between the internal temperature and the temperature setting value and the rotation speed setting signal a will be shown, and the operating state thereof will be described with reference to FIGS. 3 to 4.

Fig. 3 shows the operating conditions during cooling operation. The temperature difference in which the internal temperature is 0.5 degC higher than the temperature setting value is threshold I, and the temperature difference 0.5 degC lower is threshold II. , The zone where the temperature difference value is above the threshold I is zone a, the zone between the thresholds I and II is zone β, and the zone below the threshold II is zone γ.
The zone. The operating states are associated as shown in the table corresponding to the zones divided by these threshold values.

In the left diagram of FIG. 3, when the cooling operation is started, the internal temperature is in the α zone which is higher than the threshold value I with respect to the temperature set value, so the operation is started at the upper limit rotation speed [5400 rotations] of the rotation speed set value,
At this time, the rotation speed setting signal a corresponding to the upper limit rotation speed [5400 rotations] is output from the comparison control device 7 to the rotation speed conversion device 3, and the compressor 6 is operated. At the time when A time has elapsed after the start of operation, the temperature difference between the internal temperature and the temperature setting value (hereinafter abbreviated as temperature difference) is still in the α zone, so the rotation speed setting signal α is about to be increased by one step Since the rotation speed has been reached, operation will continue at the maximum rotation speed [5400 rotations].
After the lapse of B hours, the temperature difference reaches the β zone, so the operation is continued at that rotation speed [5400 rotations]. Further, the temperature difference is detected by the comparison control device 7 every time B has elapsed, and at the time point C when the temperature difference reaches the γ zone, the rotation speed setting signal a is lowered by one step to [4800 rotations]. After that, the same control is repeated each time B time has elapsed. In the right diagram of FIG. 3, when the temperature difference between the internal temperature and the temperature set value is between the threshold values I and II, that is, in the β zone when the cooling operation is started, the intermediate value as the rotational speed set value at this time is shown. The operation of the compressor 6 is started at the rotation speed [3200 rotations]. At the point of time A, the temperature difference is in the γ zone, so the operating speed is reduced by one step [22
00 rotation]. At the time point e after B time elapses, since the temperature difference is still in the γ zone, the rotation speed is reduced by one step to [1800 rotations]. Further, after the lapse of B time, since the temperature difference is still in the γ zone, the rotation speed is further reduced by one step [0 rotation], that is, the compressor 6 is stopped.
Next, when the time B has elapsed, when the temperature difference reaches the β zone, the operation is continued in that state and the compressor 6 is stopped. After that, the temperature difference is detected by the comparison control device 7 every time B time passes, and when the temperature difference reaches the α zone, the restart is performed after [0 rotation], and as shown in the table, the intermediate rotation speed is reached. Operate at [2200 rpm]. After that, the same control is repeated every time B time elapses, and the operating speed of the compressor 6 is controlled such that the temperature difference between the internal temperature and the temperature set value is within the temperature range of the threshold values I and II. It is a thing.

FIG. 4 is a flowchart of the comparison control device 7 showing the above control operation. The cooling operation is controlled in a continuous state by the flow of signals shown in this flowchart. In this embodiment, the operating speed is set in seven stages from 1800 to 5400. First, when the cooling operation is started, a subroutine for detecting the zone of the internal temperature is called, and the subroutine is executed from the point b to detect whether it is the α zone, the β zone, or the γ zone. From this result, the number of rotations at the start of operation is determined, and the operation is performed for A time to reach point c. After that, the subroutine is called, and if the room temperature is in the α zone, the number of revolutions is increased by one step, if it is the β zone, the operation is continued at that number of revolutions, and if it is in the γ zone, the number of revolutions is decreased by one stage. In addition, as shown at point d, if it is currently 0 revolutions, it is started from 2200 revolutions when moving up one stage. If the cooling operation does not stop, e
After performing the timer processing for the passage of time B at the point, the procedure returns to the point c and the same processing is performed. When the operation is stopped, the operation is stopped at the point f. It is controlled as described above, but when the compressor 6 is operated near 2700 rpm in this refrigerator, the compressor 6
Since noise and vibration increase due to the resonance phenomenon of piping pipes, etc., avoid setting the rotation speed during 2700 rotations ± 300 rotations, and set it to 2200 rotations and then 3200 rotations.

With such a mechanism, during the cooling operation, it becomes possible to control the refrigerating capacity by changing the rotation speed of the compressor 6 according to the cooling load, that is, the internal cold storage temperature. Also this refrigerator is
Comparison control device 7 mainly composed of the rotation speed conversion device 3 and the microcomputer 11 controlled by the digital signal a
Since it is composed of, it is possible to perform complicated control with a simple circuit configuration. Furthermore, since the rotation speed is set by the digital signal a, fluctuations or errors in the rotation speed of the compressor 6 can be suppressed to an extremely low level. In addition, the internal temperature is controlled so as to be maintained between the threshold values I and II, and the rotational speed continues between the threshold values I and II at the same value. On the other hand, it is possible to eliminate the generation of annoying fluctuating sound without subtly changing the rotational speed. Further, since the rotation speed is changed in multiple stages, noise and vibration can be suppressed to an extremely low level by setting the rotation speed in advance to avoid resonance or resonance noise of the compressor 6 or the cooling system piping. . Furthermore, at the start of the cooling operation, it is possible to perform an operation with a good start-up, and it is possible to start the operation at an appropriate rotational speed from the start of the operation. Further, by making the A and B times longer than the A time, the first temperature comparison can be performed after the safe driving is started, so that the unstable state in the initial driving can be prevented.

Although not shown in the embodiment, the threshold value is configured by two or more, and the number of revolutions is increased or decreased by one step each time the temperature difference between the internal temperature and the temperature setting value falls below the threshold value. The control to be performed can also be realized with this configuration as it is, and more complicated and fine control can be performed.

EFFECTS OF THE INVENTION As is clear from the above description, the refrigerator of the present invention is provided with a comparison control device that sends rotation speed setting signals to a plurality of stages based on the difference between the internal temperature and the temperature setting value, and the rotation speed setting signal. It comprises a rotation speed conversion device that changes the rotation speed of the compressor to multiple stages, and compares the difference between the in-compartment temperature and the temperature setting value with a preset threshold value at predetermined time intervals, and determines the predetermined value according to the result. Since the comparison control device is configured to sequentially increase or decrease the rotation speed of the compressor for each time or maintain the current state, the circuit configuration becomes simple and
It is possible to suppress fluctuations or errors in the rotation speed of the compressor to an extremely low level, and to obtain an effect that vibration and noise can be made extremely low by setting the rotation speed to avoid resonance of the compressor or cooling system piping. is there.

In addition, by configuring the threshold value to be set in advance to two or more, the rotation speed of the compressor does not change between these threshold values, and the rotation speed slightly fluctuates in response to a slight temperature fluctuation in the refrigerator. It is possible to prevent the generation of annoying fluctuating sound without performing.

Further, by determining the rotation speed at the start of operation in accordance with the zones divided by the threshold value, the start-up operation characteristic is improved, and the operation can be started at an appropriate rotation speed from the start of operation.

In addition, since the predetermined time interval for detection is changed between when the operation is started and when the internal temperature is stable, it is possible to avoid detection and control in an unstable state at the beginning of operation, and control performance is improved. The effect that can be improved is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a refrigerator according to an embodiment of the present invention, FIG. 2 is a control circuit diagram of the refrigerator, FIG. 3 is an operation explanatory diagram of the refrigerator, FIG. 4 is a flowchart of the operation, and FIG. It is a control system figure in the conventional refrigerator. 3 ... Rotation speed conversion device, 6 ... Compressor, 7 ... Comparison control device, a ... Rotation speed setting signal.

Claims (4)

[Claims] 1. A comparison control device for transmitting a rotation speed setting signal to a plurality of stages based on a difference between an internal temperature and a temperature set value, and a rotation speed of a compressor to a plurality of stages by the rotation speed setting signals of the plurality of stages. The comparison control device compares the difference between the internal temperature and the temperature set value with a preset threshold value at predetermined time intervals, and the compression is performed at predetermined time intervals according to the result. Refrigerator configured to sequentially increase or decrease the number of rotations of the machine or maintain the current state. 2. The threshold value to be preset is composed of at least two threshold values, and the number of revolutions of the compressor is sequentially set every predetermined time corresponding to the zones divided by the threshold values. The refrigerator according to claim 1, which is configured to rise, fall, or maintain the current state. 3. The refrigerator according to claim 2, wherein the comparison control device is configured to start operation from a rotational speed set value corresponding to a zone divided by a threshold value at the time of operation start. 4. The refrigerator according to claim 3, wherein the comparison control device is configured such that the time interval of the predetermined time is changed at the time of starting operation and when the temperature inside the refrigerator is stable.