JPH0266612A - Temperature control circuit for refrigerator - Google Patents

Abstract

PURPOSE:To maintain the proper foodstuff storing ability of a refrigerator until the abnormality of a sensor means is recovered by switching the control mode so as to perform the time control of a driving means via a time counting means in the case of detecting the occurrence of the abnormality of the sensor means. CONSTITUTION:For instance, an intra-refrigerator temperature sensor of a sensor means 1 has a trouble of the disconnection or conduction, and the voltage value V of a sensor signal A is set out of the set voltage range of a sensor abnormality deciding means 4. Thus an abnormality deciding signal C is outputted. A control mode switch means 6 receives the input of the signal C and switches the signal supplied to a driving means 3 to the output D of a time counting means 5 from the output B of a temperature deciding means 2. The means 5 decides the working time and the halt time of the means 3 after the input of the signal C based on the real working time and the real halt time of the means 3 set under the control of the means 2 before input of the signal C. In this case, both the working time and the halt time of the means 3 are set variable and a compressor motor is operated or stopped in accordance with the using conditions of the out-refrigerator temperatures, the intra-refrigerator load, etc.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a temperature control circuit for a refrigerator.

(Prior Art) FIG. 4 is a block diagram showing the configuration of a temperature control circuit of a conventional refrigerator.

This temperature control circuit includes a drive means 3 for operating or stopping the motor of the refrigerator cooling compressor. code 1
is a sensor means whose output voltage value V changes according to the temperature inside the refrigerator. Specifically, this sensor means is a voltage dividing circuit in which a DC power supply is connected to the ground through an internal temperature sensor and a resistor in series, and the internal temperature sensor has a negative resistance value, for example. It consists of a thermistor with characteristics.

The output of the sensor signal A is obtained from this voltage division point.

Temperature determination means 2 compares the output voltage value V of sensor means 1 with a set voltage value and operates or deactivates drive means 3 to operate the compressor motor only when the temperature inside the refrigerator is equal to or higher than the set temperature. outputs a binary logic signal B that causes The sensor abnormality determination means 4 outputs an abnormality determination signal C when the output voltage value V of the sensor means 1 falls outside a set voltage range that includes the voltage range during normal operation of the refrigerator and is set wider than this range. . The display circuit 7 displays this abnormality determination signal C.

The conventional refrigerator temperature control circuit described above uses the sensor means 1, the temperature determination means 2, and the drive means 3 to maintain the internal temperature near the set temperature.

Now, a disconnection failure or a continuity failure may occur in the internal temperature sensor of the sensor means 1.

When a disconnection fault occurs, the voltage value V of the sensor signal A becomes 0, and the sensor abnormality determining means 4 outputs the abnormality determination signal C. Furthermore, when a continuity failure occurs, the voltage value V of the sensor signal A becomes the same high voltage as the DC power supply. This voltage value is also outside the set voltage range of the sensor abnormality determination means 4, and an abnormality determination signal C is output. Therefore, when a disconnection failure or a continuity failure occurs in the internal temperature sensor, this failure is displayed on the display means 7.

(Problems to be Solved by the Invention) In the conventional refrigerator temperature control circuit described above, when the occurrence of a disconnection failure or continuity failure is detected, it is only necessary to display this on the display means 7 and issue an alarm. Since the operation of the drive means 3 was continued to be controlled based on the sensor signal A which was not a normal value, the following problem occurred when it took a long time to recover from the abnormality by repair.

That is, in the case of a disconnection failure, the drive means 3 continues to stop operating even if the internal temperature actually exceeds the set temperature.

Therefore, the temperature inside the refrigerator becomes abnormally high, leading to food spoilage.

In the case of a continuity failure, the drive means 3 continues to operate even if the temperature inside the refrigerator is actually lower than the set temperature. therefore,
The inside of the refrigerator becomes supercooled and the food freezes.

In view of the above points, the present invention provides a temperature control circuit that can maintain an appropriate food storage capacity of a refrigerator until the abnormality is recovered even when an abnormal output voltage value of a sensor means occurs. The purpose is to

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, a temperature control circuit for a refrigerator according to the present invention has a configuration shown in FIG. 1. However, since the configurations of the sensor means 1, temperature determination means 2, drive means 3, and sensor abnormality determination means 4 are the same as the conventional ones explained in FIG. 4, their explanations will be omitted.

The clock means 5 outputs a binary logic signal that activates or deactivates the drive means 3 for a predetermined period of time.

The output B of the temperature determining means 2 is not input directly to the driving means 3, but is inputted to the driving means 3 via the control mode switching means 6. When the control mode switching means 6 receives the input of the abnormality determination signal C, the control mode switching means 6 switches the binary logic signal B outputted from the temperature determination means 2 to the binary logic signal outputted from the timekeeping means 5 and is driven. Supply means 3.

In addition, when taking into consideration the usage conditions of the refrigerator, in the temperature control circuit for the refrigerator according to the present invention described above, the timer 5 is configured to control the temperature determination means 2 before the abnormality determination signal C is input.
It is preferable to determine the operating time and the operating stop time of the drive means 3 after the abnormality determination signal C is manually applied based on the actual operating time and the actual operating stop time of the drive means 3 under the control of the abnormality determination signal C.

(Function) When there is no abnormality in the output voltage value of the sensor means 1, that is, when the voltage value V of the sensor signal A is within the set voltage range of the sensor abnormality determination means 4, the abnormality determination signal C is output. There isn't. Therefore, the control mode switching means 6 is switched to the temperature determining means 2 side, and this temperature determining means 2
The operation of the drive means 3 is controlled by the binary logic signal B output from the drive means 3. Therefore, the operation of the compressor motor is controlled according to the temperature inside the refrigerator.

In the sensor means 1, for example, when a disconnection failure or a continuity failure occurs in the internal temperature sensor and the voltage value V of the sensor signal A falls outside the set voltage range of the sensor abnormality determination means 4, an abnormality determination signal C is output from this determination means. be done. When the control mode switching means 6 receives this abnormality determination signal C, it switches the signal supplied to the drive means 3 from the output B of the temperature determination means 2 to the output of the time measurement means 5. At this time, both the operation time and the operation stop time of the drive means 3 are determined by the time measurement of the time measurement means 5. In other words, the operation of the compressor motor is time-controlled regardless of the apparent internal temperature determined by the sensor means 1 and the temperature determination means 2.

The temperature determination means 2 before the time measurement means 5 inputs the abnormality determination signal C
The drive means 3 after inputting the abnormality determination signal C based on the actual operating time and the actual operation stop time of the drive means 3 under the control of
When determining the activation time and its deactivation time,
The operating time and the operating stop time of the driving means are variable, and the compressor motor is operated or stopped in accordance with usage conditions such as the temperature outside the refrigerator and the load inside the refrigerator.

(Example) FIG. 2 is a circuit diagram of a temperature control circuit for a refrigerator according to an example of the present invention.

10 is a sensor circuit in which one end of the internal temperature sensor 11 and one end of the resistor 12 are connected at a connection point 13. The internal temperature sensor 11 is made of, for example, a thermistor whose resistance value has negative temperature characteristics.

The other end of the internal temperature sensor 11 is connected to a DC power supply Vcc, and the other end of the resistor 12 is connected to ground, forming a voltage dividing circuit. The voltage at the connection point 13 is output as a sensor signal SS. This sensor circuit 1o corresponds to the sensor means 1 described above.

Reference numeral 20 denotes a temperature determination circuit, and a sensor signal SS is input to an inverting input terminal of a comparator 21. The non-inverting input terminal of the comparator 21 is connected to the resistor 22, 23, 24
It is connected to the DC power supply VCC, ground, and its own output terminal through the terminal. The binary logic signal output of the comparator 21 is input to the microcomputer 40 as the output of the temperature determination circuit 20, that is, the temperature determination signal SF.

This temperature determination circuit 20 corresponds to the temperature determination means 2 described above.

Reference numeral 30 denotes a sensor abnormality determination circuit, which includes two comparators 31 and 3B. The sensor signal SS is input to the inverting input terminal of the comparator 31.

The non-inverting input terminal of the comparator 31 is connected to the resistor 32°3.
3 to the DC power supply Vcc and ground, respectively. The binary logic signal output of the comparator 31 is input to the microcomputer 40 as a short-circuit abnormality determination signal SU. Further, the sensor signal SS is input to the non-inverting input terminal of the comparator 3B. The inverting input terminal of comparator 36 is connected to resistor 37. It is connected to the DC power supply Vcc and the ground via H, respectively. The binary logic signal output of the comparator 36 is input to the microcomputer 4o as an open abnormality determination signal SL. Two comparators 31
．． A sensor abnormality determining circuit 30 having a so-called window comparator consisting of 36 corresponds to the sensor abnormality determining means 4. That is, the comparator 31 determines the upper limit of the voltage value V of the sensor signal SS, and the comparator 36
determines the lower limit of this voltage value V. The upper and lower limit setting voltages are
It is set wider than this to include the voltage range during normal operation of the refrigerator.

The microcomputer 40 has an internal timer 41 and an input/output board. However, the timer 41 can be configured with a software timer. This microcomputer 40 corresponds to the time measuring means 5 and control mode switching means 6, as will be described later.

A compressor control signal sc, which is a binary logic signal output from the microcomputer 4o, is input to the base of an NPN transistor 52 via a resistor 51 in a compressor control circuit 50. The emitter of this transistor is grounded, and the collector is connected to a DC power supply Vcc via a relay coil 53. A diode 54 is connected to both ends of this coil with its cathode facing the DC power supply Vcc side.

An a-contact 55 of a relay having a coil 53 is connected to an AC power source 57 in series with the compressor motor 5G.

This compressor control circuit 50 corresponds to the drive means 3.

In addition, the display signal SD output from the microcomputer 40 to indicate an abnormality in the internal temperature sensor 11 is
It is connected to the cathode of a light emitting diode 61 in the display circuit 60 . The anode of this light emitting diode 61 is connected to a DC type [Vcc] via a resistor 62.

The memory 70 stores the operating time TON and the operating stop time TOFF of the compressor control circuit 50, which are used when an abnormality occurs in the internal temperature sensor 11. These times TON and TOFF are determined in advance through experiments and the like, and are read out from the memory 70 as a time signal ST and sequentially set in the timer 41 in the microcomputer 40.

FIG. 3 is a flowchart showing the operation of the microcomputer 40. Hereinafter, the operation of the temperature control circuit for a refrigerator according to an embodiment of the present invention will be explained based on FIG. 2 and this flowchart.

In step 1, the display signal SD at H level is output to turn off the light emitting diode 61 of the display circuit 60.

After this initialization, in steps 2 and 3,
Check the logical values of the short-circuit abnormality determination signal SU and the open abnormality determination signal SL.

Since the upper and lower limit set voltages of the sensor abnormality determination circuit 30 are set wider than these to include the voltage range during normal operation of the refrigerator, a continuity failure of the refrigerator internal temperature sensor 11 occurs and the voltage value of the sensor signal SS is When V becomes the same high voltage as the DC power supply Vcc, this voltage value V exceeds the upper limit setting value of the comparator 31. Therefore, the short-circuit abnormality determination signal SU at the L level is input to the microcomputer 40. When a disconnection failure occurs in the internal temperature sensor 11 and the voltage value V of the sensor signal SS becomes 0, this voltage value V is applied to the comparator 36.
below the lower limit setting value. Therefore, the open abnormality determination signal SL at the L level is input to the microcomputer 40. In a normal state in which neither a conduction failure nor a disconnection failure occurs in the internal temperature sensor 11, both the short circuit abnormality determination signal SU and the open abnormality determination signal SL are at H level.

If both the short-circuit abnormality determination signal SU and the open abnormality determination signal SL are at H level, the process proceeds to step 4, but if either is at L level, the process jumps to step 7.

In step 4, the logical value of the temperature determination signal SF is checked.

The temperature determination signal SF output from the temperature determination circuit 20 is
Normally, the L level is reached when the internal temperature is above the set temperature, and the H level is set when the temperature is lower than the set temperature. Since the resistance value of the internal temperature sensor 11 has negative temperature characteristics, the voltage value V of the sensor signal SS increases as the temperature increases. In other words, when the temperature inside the refrigerator rises and exceeds the set temperature,
The output of the comparator 21, that is, the temperature judgment signal SF is L
become the level. Conversely, when the temperature inside the refrigerator decreases and becomes lower than the set temperature, the temperature determination signal SF becomes H level.

However, the set voltage of the comparator 21 requires a resistor 24.
Hysteresis is provided by positive feedback.

The microcomputer 40 outputs an L level temperature determination signal S.
Upon receiving the input of F, in step 5, the compressor control signal SC of H level is output. At this time, in the compressor control circuit 50, the transistor 52 is turned on, the coil 53 is energized, and the a contact 55 is turned on. Therefore, the AC @[57 causes the compressor motor 56
is driven to cool the inside of the refrigerator.

On the other hand, when the microcomputer 40 receives the temperature determination signal SF at the H level, the compressor control signal SC at the L level is output in step 6. At this time, the transistor 52 in the compressor control circuit 50 is turned off, and the a contact 55 is turned off. therefore,
The driving of the compressor motor 56 is stopped, and the cooling inside the refrigerator is stopped.

As described above, if there is no abnormality in the internal temperature sensor 11 and there is no abnormality in the voltage value of the sensor signal SS, the sensor signal SS
Since the voltage value V always corresponds to the internal temperature, the microcomputer 40 executes the loop of steps 2.3.4 and 5 or the loop of steps 2, 3.4 and 6, and adjusts the compressor voltage according to the internal temperature Motor 56 is activated or deactivated.

However, if a conduction failure or a disconnection failure occurs in the internal temperature sensor II, the process jumps from step 2 or step 3 to step 7 as described above.

First, in step 7, an L level display signal SD is output to light the light emitting diode 61 of the display circuit 60. As a result, the occurrence of an abnormality in the internal temperature sensor 11 is displayed as an alarm.

In step 8, the time during which the compressor motor 56 should be operated, that is, the operating time TO of the compressor control circuit 50 is determined.
N is read out from the memory 70 and set in the timer 41 to start timing. In step 9, it is determined whether or not the timer 41 has completed counting the operating time TON. If this has not been completed, in step 10, the timer 41 waits for completion of counting while outputting the H level compressor control signal SC. Therefore, as in step 5, the compressor motor 56 is driven to cool the inside of the refrigerator.

When the timer 41 completes counting the operating time TON, the process jumps from step 9 to step 11.

In step 11, the operation stop time TOFF is stored in the memory 70.
, and sets it in the timer 41 to start measuring time. In step 12, it is determined whether or not the timer 41 has completed counting the operation stop time TOFF. If this has not been completed, in step 13, the timer 41 determines whether or not the timing has been completed while outputting the L level compressor control signal SC. wait. Therefore, as in the case of step 6, the driving of the compressor motor 56 is stopped, and the cooling inside the refrigerator is stopped.

When the timer 41 completes counting the operation stop time TOFF, the process returns from step 12 to step 8.

Thereafter, the execution of internal cooling in steps 8 to 10 and the stopping of internal cooling in steps 11 to 13 are sequentially repeated. That is, the compressor motor 56 is controlled on and off depending on the time, and the temperature inside the refrigerator is maintained within an appropriate temperature range. This time control mode continues even if the failure of the internal temperature sensor 11 is temporarily recovered. In other words, the time control mode of steps 8 to 13 is canceled only when the refrigerator is turned off, the failed internal temperature sensor 11 is replaced with a healthy one, and then the power is turned on again. returns to normal operating mode.

Note that the operating time T is stored in the memory 70.

N and the operation stop time TOFF may be determined by the microcomputer 40 itself in the following manner.

That is, first, the timer 41 measures time while executing the loop of steps 2, 3, 4, and 5 and outputting the H level compressor control signal SC. This timing continues until the execution control of the microcomputer 40 shifts to the loop of steps 2, 3, 4, and 6 when the temperature judgment signal SF rises, and at this transition, the timing result of the timer 41 is used as the operating time TON. The data is stored in the memory 70. This TON
Simultaneously with the data storage, time measurement by the timer 41 is started. At this time, the timer 41 measures the output time of the compressor control signal SC at the L level, and this time measurement occurs when the temperature determination signal SF transitions from the H level to the L level and the execution control of the microcomputer 40 starts at step 2.3. Continue until you return to loops 4 and 5. During this transition, timer 4
The timing result of step 1 is stored in the memory 70 as the operation stop time TOFF.
Store in. Thereafter, time measurement by the timer 41 and updating of the operating time TON and the operating stop time TOFF are repeated. In this case, the values of the times TON and TOFF used in steps 8 and 11 are equal to the actual values of the internal temperature sensor 11 immediately before the failure occurs. In addition, the timer 41
The average value of a plurality of timing results may be stored in the memory 70 as the operating time TON. The same applies to the operation stop time TOFF.

In addition, in the embodiment described above, a comparator is used in the temperature determination circuit 20 and the sensor abnormality determination circuit 30, but the sensor signal SS is converted into a multi-bit digital value by an A/D converter, and this digital value is is input into the microcomputer 4o, and this microcomputer 40
The above-mentioned temperature determination and sensor abnormality determination may be performed by.

[Effects of the Invention] As explained above, the temperature control circuit for a refrigerator according to the present invention operates the drive means according to the internal temperature obtained by the sensor means when there is no abnormality in the output voltage value of the sensor means. On the other hand, if an abnormality occurs in the sensor means, the abnormality is detected by the sensor abnormality determination means, and the control mode is switched so that the time control of the drive means is performed by the timer means. Even if this occurs, the proper food storage capacity of the refrigerator can be maintained until the abnormality is resolved. Therefore, there is an effect that more time is available for repairing the sensor means.

The timer calculates the operating time and stop time of the drive means after the abnormality determination signal is input based on the actual operating time and actual stop time of the drive means under the control of the temperature determination means before the abnormality determination signal is input. If determined, it is possible to control the operation of the compressor motor in accordance with usage conditions such as outside temperature and internal load.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a temperature control circuit of a refrigerator according to the present invention. FIG. 2 is a circuit diagram of a temperature control circuit of a refrigerator according to an embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of a temperature control circuit of a refrigerator according to an embodiment of the present invention. Flowchart showing the operation of FIG. 4 is a block diagram showing the configuration of a temperature control circuit of a conventional refrigerator. Explanation of symbols ■...Sensor means, 2...Temperature determination means, 3...
Driving means, 4... Sensor abnormality determination means, 5... Time measuring means, 6... Control mode switching means, 7... Display means, 10... Sensor circuit, 11... Internal temperature sensor ,
20...Temperature judgment circuit, 30...Sensor abnormality judgment circuit, 4o...Microcomputer, 41...Timer, 50...Compressor control circuit, 56...Compressor motor, 6o...Display Circuit, 70...Memory, SC...Compressor control signal, SD...Display signal, SF...Temperature judgment signal, SL...Open abnormality judgment signal, SS...Sensor signal, ST...・Time signal,
SU...short circuit abnormality determination signal, TOFF...operation time, TON...operation stop time.

Claims (1)

[Claims] 1. A sensor means that includes a drive means for starting or stopping a motor of a refrigerator cooling compressor, and whose output voltage value changes according to the temperature inside the refrigerator, and an output voltage value of the sensor means. temperature determining means for outputting a binary logic signal that operates or deactivates the driving means to operate the compressor motor only when the internal temperature of the refrigerator is equal to or higher than the set temperature by comparing the temperature with a set voltage value; Temperature control for a refrigerator, comprising sensor abnormality determination means that outputs an abnormality determination signal when the output voltage value of the sensor means falls outside a set voltage range that includes the voltage range during normal operation of the refrigerator and is set wider than this range. In the circuit, a clock means outputs a binary logic signal for activating or deactivating the drive means for a predetermined period of time, and a binary value output from the temperature determination means when receiving the input of the abnormality determination signal. 1. A temperature control circuit for a refrigerator, comprising control mode switching means for switching a logic signal to a binary logic signal output from the timer and supplying the same to the drive means. 2. The timing means calculates the operating time and stoppage of the drive means after the abnormality determination signal is input based on the actual operating time and actual stoppage time of the drive means under the control of the temperature determination means before the abnormality determination signal is input. 2. The temperature control circuit for a refrigerator according to claim 1, wherein the temperature control circuit determines the time.