JPH08240347A - Control device of freezing cycle pressure - Google Patents

Abstract

PURPOSE: To provide a less-expensive surely operating pressure control device by a method wherein a suction side pressure sensor for a compressor is applied as a semiconductor pressure sensor and a pressure sensor for discharging side is applied as a mechanical pressure switch. CONSTITUTION: In a pressure control device in which an operation of a freezing cycle pressure device is stopped when a high pressure is more than a set value, or a low pressure becomes a refrigerant pressure less than a set value so as to prevent a seizing at a compressor during its freezing cycle, there are provided a semiconductor pressure sensor 2 for use in sensing a suction pressure of the compressor 100 and a mechanical type pressure switch 3 for use in sensing a discharging pressure of the compressor 100. Then, an output signal of the pressure sensor 2 is stored in a RAM 72 through an A/D converter means 4. In the case that a mean value of the suction side pressure is larger than an ON-set value of a controlling condition stored in EEPROM 73, an operating signal output means 10 is turned on. In addition, in the case that the discharging pressure is increased to be higher than the set value and the pressure switch 3 is turned off, a signal for turning off the operating signal output means 10 is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control device for controlling the pressure of a refrigerant in a refrigerating cycle of a refrigerator. Furthermore, the present invention relates to a pressure control device suitable for preventing seizure of a compressor of a refrigeration cycle.

[0002]

2. Description of the Related Art In a refrigerating cycle such as a refrigerating apparatus or a cooling apparatus constituted by connecting a compressor, a condenser, an expansion valve and an evaporator in a circulating manner by pipes, refrigerant pipes before and after the compressor are provided with high or low pressure. Refrigerant pressure is generated, which may impair the normal operation of the refrigeration cycle depending on the magnitude of this pressure. In order to solve this problem, conventionally, pressure switches were attached to the refrigerant pipes before and after the compressor of the refrigeration cycle,
When the high pressure becomes equal to or higher than the set value or the low pressure becomes equal to or lower than the set value, these pressure switches are operated to stop the operation of the apparatus. Further, no consideration was given to confirming the cause of the high pressure when the high pressure is detected and the pressure switch operates.

However, these pressure switches
This is a mechanical means, and the operating pressure is set by turning the adjusting screw to adjust the amount of expansion and contraction of the spring.Therefore, there is a limit to the setting accuracy and only a rough value can be set. It was not possible to perform high motion control. Further, in turning on and off such a mechanical pressure switch, one value, for example, an off operating pressure is set by turning the adjusting screw, and the on operating pressure causes a differential pressure with respect to the off operating pressure. Since the expansion and contraction of the spring is set by turning the differential pressure adjusting screw, when the on-off operation is set with a pressure of 0 Kgf / cm ² , this differential pressure is set incorrectly. There was also a risk of doing it.

In the mechanical pressure switch, the adjusting screw may be loosened due to the vibration or shock of the refrigerant pipe, and the operating set value may move. Further, in the conventional mechanical pressure switch, the output of the on-off operation may be generated. There has been a problem that it is difficult to arbitrarily control the delay time.

In the pressure control of the refrigeration system, when the refrigeration cycle is controlled to be turned on and off, in order to prevent chattering due to minute vibrations of the pressure and frequent on and off of the refrigeration cycle, a predetermined value is set. Although it is necessary to provide the on / off pressure difference, the on / off value may be set to a minute setting value within the on / off pressure difference setting range.

Further, at the time of test operation of the refrigeration system, it is necessary to count the number of on-off operations within a predetermined time to check whether or not the system operates normally. If the side pressure and the discharge side pressure are balanced, there is a problem that the time for restarting the compressor becomes long and the time required for the inspection becomes long.

The manual reset type pressure switch is used for notifying or recording to the maintenance manager that the refrigerator has stopped due to an increase in high pressure. For example, when the cooling water becomes insufficient, if the automatic return type is used, the pressure on the high-pressure side rises and falls quickly, and if the high-pressure switch follows it, a short cycle occurs when the compressor starts and stops, It may burn out or damage other equipment.

Since the pressure switch used in the pressure control device is a safety device that operates by detecting an abnormally high pressure, once the high voltage side cuts off the electric circuit, it is dangerous to enter into automatic operation without ascertaining what the cause is. It will be repeated again. If the pressure switch is a manual reset type,
You can investigate the cause of the dangerous state, correct it, and restart it manually. From this point of view, the automatic reset type pressure switch can be regarded as a safety limit switch, and the manual reset type pressure switch can be regarded as a hazard prevention alarm switch.

[0009]

In view of the above problems, the first invention of the present application uses a semiconductor pressure sensor for the suction side pressure detecting means and a mechanical pressure switch for the discharge side pressure detecting means. An object of the present invention is to provide a pressure control device capable of easily setting a highly accurate operating pressure value.

It is another object of the present invention to provide a pressure control device which prevents the discharge side pressure detecting means from malfunctioning due to pulsation of discharge pressure.

A third object of the present invention is to provide a pressure control device capable of confirming the cause of increase in high pressure by self-holding the output of the mechanical pressure switch.

It is another object of the present invention to provide a pressure control device which prevents the discharge side pressure detection means from malfunctioning due to pulsation of discharge pressure without using any special monitoring means.

Further, in the fifth invention, when the compressor is repeatedly turned on and off, after the operation of the compressor is stopped, the compressor is restarted before the suction side pressure and the discharge side pressure are balanced. An object of the present invention is to provide a pressure control device adapted to the above.

[0014]

In order to achieve the above object, the first invention of the present application is a pressure detecting means for detecting the suction side pressure and a pressure for detecting the discharge side pressure of a compressor during a refrigeration cycle. In the pressure control device of the refrigeration cycle, which is provided with a detection means, and which stops the compressor when the suction side pressure is equal to or lower than the minimum pressure setting or the discharge side pressure is equal to or higher than the maximum pressure setting value, The pressure detecting means for detecting the suction side pressure is a semiconductor pressure sensor, and the pressure detecting means for detecting the discharge side pressure is a mechanical pressure switch.

The second invention of this application comprises pressure detecting means for detecting the suction side pressure of the compressor in the refrigeration cycle and pressure detecting means for detecting the discharge side pressure, and the suction side pressure is below the minimum pressure setting. In the pressure control device of the refrigeration cycle, in which the compressor is stopped when the discharge side pressure becomes equal to or higher than the maximum pressure set value, the semiconductor pressure sensor is used as the pressure detecting means for detecting the suction side pressure. The pressure detecting means for detecting the discharge side pressure is a mechanical pressure switch, and means for delaying the output of the mechanical pressure switch is provided.

The third invention of this application comprises pressure detecting means for detecting the suction side pressure of the compressor in the refrigeration cycle and pressure detecting means for detecting the discharge side pressure, and the suction side pressure is below the minimum pressure setting. In the pressure control device of the refrigeration cycle, in which the compressor is stopped when the discharge side pressure becomes equal to or higher than the maximum pressure set value, the semiconductor pressure sensor is used as the pressure detecting means for detecting the suction side pressure. The pressure detecting means for detecting the discharge side pressure is a mechanical pressure switch, and means for holding the output of the mechanical pressure switch is provided.

The fourth invention of this application comprises pressure detecting means for detecting the suction side pressure and pressure detecting means for detecting the discharge side pressure of the compressor in the refrigeration cycle, wherein the suction side pressure is equal to or lower than the minimum pressure setting. In the pressure control device of the refrigeration cycle, in which the compressor is stopped when the discharge side pressure becomes equal to or higher than the maximum pressure set value, the semiconductor pressure sensor is used as the pressure detecting means for detecting the suction side pressure. The pressure detecting means for detecting the discharge side pressure is a temperature sensor.

The fifth invention of this application comprises pressure detecting means for detecting the suction side pressure of the compressor in the refrigeration cycle and pressure detecting means for detecting the discharge side pressure, and the suction side pressure is below the minimum pressure setting. In the pressure control device of the refrigeration cycle, which stops the compressor when the discharge side pressure becomes equal to or higher than the maximum pressure set value, the pressure difference between both pressure detection means has a preset minimum difference. Restart the compressor when pressure drops below.

[0019]

In the first aspect of the present invention, the semiconductor pressure sensor is used as the pressure detecting means for detecting the suction side pressure of the compressor during the refrigeration cycle, and the mechanical pressure switch is used as the pressure detecting means for detecting the discharge side pressure. When the pressure on the suction side is less than or equal to the minimum pressure setting, or when the pressure on the discharge side is greater than or equal to the maximum pressure setting value, with a configuration that is less expensive than using all pressure detection means as semiconductor pressure sensors. The compressor can be surely stopped.

According to a second aspect of the present invention, a semiconductor pressure sensor is used as the pressure detecting means for detecting the suction side pressure of the compressor in the refrigeration cycle, and a mechanical pressure switch is used as the pressure detecting means for detecting the discharge side pressure. Since the means for delaying the output of the mechanical pressure switch is provided, the malfunction due to the pulsation of the discharge pressure can be prevented with a simple means.

According to the third aspect of the invention, since the self-holding means for holding the pressure of the mechanical pressure switch by itself is used, the cause of the increase in the high pressure is investigated, the cause is eliminated, and the restart is manually performed. You can

In the fourth aspect of the invention, the semiconductor pressure sensor is used as the pressure detecting means for detecting the suction side pressure of the compressor during the refrigeration cycle, and the temperature sensor is used as the pressure detecting means for detecting the discharge side pressure. It is possible to prevent malfunction due to pulsation of the discharge pressure without monitoring the pressure pulsation.

According to a fifth aspect of the invention, the differential pressure between the outputs of the pressure detecting means for detecting the suction side pressure and the pressure detecting means for detecting the discharge side pressure of the compressor during the refrigeration cycle becomes a preset differential pressure value. I tried to restart the compressor when
When the compressor is repeatedly turned on / off, it can be easily restarted.

[0024]

1 is a schematic view of a refrigerating cycle, which comprises a compressor 100, a condenser 200, an expansion valve 300, an evaporator 400 and a pipe 500 connecting each device. The refrigerant in a gas state is compressed by the compressor 100, has its pressure increased, and is delivered from the discharge port 101 to the condenser 200, where it condenses heat to be transformed into a liquid. The liquid refrigerant is sent to the evaporator 400 via the expansion valve 300. In the evaporator 400, the refrigerant, which has absorbed the heat of vaporization, transformed into a gas, and whose pressure has dropped, is sent to the suction port 102 of the compressor 100. In such a refrigeration cycle, the compressor 100
When the pressure of the discharge port 101 exceeds a predetermined value, or when the pressure of the refrigerant sent from the suction port 102 falls below the predetermined value, the operation of the compressor 100 is stopped to destroy the compressor 100. In order to prevent seizure, the low pressure detecting means 600 is provided near the suction port 102, and the high pressure detecting means 700 is provided near the discharge port 101, respectively.
The operation of the compressor 100 is controlled to protect the compressor 100. The pressure control device 1 is formed by the low pressure detection means 600, the high pressure detection means 700, and the control means (not shown).

The present invention is an invention relating to the pressure control device 1 of the refrigeration cycle, and FIG. 2 is a block diagram showing a schematic configuration of a first embodiment of the pressure control device according to the present invention. The configuration will be described below with reference to FIG. The pressure control device 1 according to the present invention includes a semiconductor pressure sensor 2 for detecting the suction pressure of the compressor 100, a mechanical pressure switch 3 for detecting the discharge pressure of the compressor 100, and a digital analog output of the semiconductor pressure sensor. Analog converted to value
Digital conversion means (A / D conversion means) 4, interface 5 for inputting the output of mechanical pressure switch 3 to the CPU, central processing unit (CPU) 6, and storage means 7
A display means 8, an operation switch 9 for setting an operating pressure value and the like, and an output relay 10 as an operation signal output means for on / off controlling the operation of the compressor to be controlled.
And a reset means 11 for resetting the output hold state by the pressure switch.

The semiconductor pressure sensor 2 is arranged so as to detect the pressure in the pipe 500 near the suction port 102 of the compressor 100, and outputs an analog electric signal proportional to the detected pressure. The mechanical pressure switch 3 is the discharge port 1 of the compressor 100.
The pressure switch is arranged so as to detect the pressure of the pipe 500 near 01 and is turned on / off at a preset detection pressure. The A / D conversion means 4 converts the output of the semiconductor pressure sensor into a digital value. Interface 5
Is an interface unit for interfacing the pressure switch 3, the display unit 8, the operation switch 9, the output relay 10, and the CPU 6.

The storage means 7 is a read-only memory (R) for storing a control program and a voltage-pressure conversion table.
OM) 71 and the control calculation result and the like are temporarily stored (RA
M) 72 and a storage means (EEPROM) 73 that stores the control contents such as various set values input from the operation switch 9 and retains the stored contents even after the power supply is cut off. The display means 8 displays control conditions such as the detected pressure value of the semiconductor pressure sensor 2 or the set value of the operating pressure.
The operation switch 9 is means for inputting control conditions such as operating pressure. The output relay 10 outputs an operation signal that controls the operation of the compressor 100 that is the control target.

The function of the pressure control device of the present invention will be described with reference to FIG. The first pressure detecting means 2 for detecting pressure and outputting an electric signal of an analog amount proportional to the pressure includes a semiconductor pressure sensor, a resistance conversion type pressure sensor using the piezo effect, a capacitance type pressure sensor, and a strain gauge. A pressure detector 21 including a pressure sensor used, for example, −
It is composed of a pressure-voltage converting means 22 for converting a pressure of 0.5 to 5 Kgf / cm ² into a voltage of 0.35 to 4.65 V.

The second pressure detecting means 3 is a mechanical pressure switch which is commonly used, and is a switch which is turned on when the pressure in the pipe 500 is below a predetermined value and is turned off when the pressure inside the pipe 500 is above a predetermined pressure. It is possible to use a pressure switch for turning on / off the micro switch by the reversing operation of the reversing plate by pressure, a pressure switch for turning on / off the micro switch by a bellows and a return spring, and the like. For example, an example of a diaphragm type pressure switch is shown in FIG. In FIG. 4, the mechanical pressure switch 3 includes two contacts 31 that are in a conductive state when not operating, an actuation rod 32 that releases the connection state of the two contacts, and a diaphragm 33.
A joint 34 connected to the pipe 500, a receiver 35 brazed to the joint 34, a case 36, a terminal 37 connected to the contact 31, a space 38, and a switch lever 39. Diaphragm 33 and its upper and lower receivers 3
The outer circumference of No. 5 is hermetically sealed by arc welding. When the pressure in the space 38 connected to the pipe 500 increases, the diaphragm 33 flexes outward to push up the actuation rod 32 and release the contact point 31 against the switch lever 39, and when the internal pressure in the space 38 decreases, the diaphragm 33 moves. Space 3
The switch lever 39 of the contact point 31 returns to the 8 side, the switch rod 39 of the contact point 31 returns, the operation rod 32 is pushed down, and the contact point 31 returns to the contact state.

The output of the first pressure detecting means 2 is analog /
The digital value is converted into a digital value by the digital converting means 4, and CP
Input to U6. The CPU 6 has a function 61 for converting a voltage represented by a digital signal into pressure data, a display data conversion function 62 for converting the pressure data into data suitable for display, and a control calculation function 63 for controlling the operation of the compressor 100. And these functions can be realized by a microcomputer and software that constitute the CPU 6. The control calculation function 63 is the conversion function 61.
An operation signal for a relay drive circuit or the like for operating a solenoid valve or the like provided in the refrigeration cycle based on the pressure data converted by the above, the operation signal input from the operation signal input means 9, the data stored in the storage means, and the like. Is calculated and output, and a process of holding the operation output means off when the pressure switch is turned off is performed. Storage means 7
Is composed of a storage means for storing a control program and the like, a storage means for temporarily storing a control calculation result, and a storage means for storing control conditions and the like even when the power is cut off.

The display function is realized by the digital display means 8 such as a liquid crystal display device and displays the pressure value, the control condition and the like according to the output signal posted by the conversion function 62. The operation signal input function is realized by operation signal input means 9 for inputting signals such as set pressure and interrupt signal. The operation signal output function is realized by the operation signal output means 10 that outputs a control signal symmetrically in accordance with the signal output calculated by the control calculation function 63. The reset signal input function is realized by the reset signal input means 11 which inputs a reset signal for canceling the state in which the output of the operation signal output means 10 in which the signal from the pressure switch 3 is processed by the control calculation function 63 is held off. It

The operation mode of the first invention of this application will be described with reference to FIG. When the power of the device is turned on, a runaway detection process of sending a normal operation signal to an external runaway detection circuit is executed (S1).

The pressure value corresponding to the average value of the past ten digital data obtained in step S8 is selected from the voltage value-pressure value conversion table prepared in the storage means 71 (S2).

The pressure value converted in step S2 is converted into data suitable for display on the display means 8 (S3).

The data converted in step S3 is output to the selection display means 8 to display the pressure value (S4).

For example, it is judged whether or not the control condition setting mode is in accordance with whether or not the button for changing the control condition of the operation signal input means 9 is pressed (S5). If not in the control condition setting mode, step S1 Return processing to.

When the control condition mode is determined in step S5, the control condition is input from the operation signal input means 9, and the control condition is stored in the RAM 72 and the EEPROM 73.
To be stored. The control conditions include setting of the ON operation point (compressor operation point) and the OFF operation point (compressor stop point) of the relay during the refrigeration cycle.

There is an interrupt in the middle of steps S1 to S6,
When the detection signals from the pressure detecting means 2 and 3 are read, the following processing is performed.

The analog voltage signal corresponding to the pressure signal from the pressure detecting means 2 on the suction port 102 side of the compressor 100 is A
The / D conversion means 4 converts it into a digital signal and stores this data in the RAM 72 (S7).

The data of step S7 in the past interruption is read ten times and the average value is calculated (S8).
As a result, malfunction due to pulsation of pressure in the pipe is prevented.

The average value obtained as a result of the calculation is stored in the RAM 72 (S9).

Then, a control calculation process is executed (S1).
0). That is, when the pressure average value obtained on the suction port 102 side is larger than the ON set value of the control condition stored in the EEPROM 73, a signal for turning on the operation signal output means 10 is output, while the control condition is OFF. When it is smaller than the set value, a signal for turning off the output of the operation signal output means 10 is output.

The calculation result in step S10 is output to the operation signal output means 10 to control the operation of the compressor, which is symmetrical to the control (S11).

On the other hand, when the pressure switch 3 is turned off, control calculation processing is executed based on this signal (S).
10). That is, when the discharge pressure of the compressor 100 rises above the set value and the pressure switch 3 is turned off, a signal for turning off the operation signal output means 10 is output, and that state is maintained thereafter. In this state, the reset signal input means 1
When 1 is turned on, a signal for turning on the output of the operation signal output means 10 is output.

The calculation result in step S10 is output to the operation signal output means 10, and the compressor 100 having a control symmetry.
The operation is controlled (S11), and the interrupt process ends.

By the above operation, when the pressure on the input side of the compressor 100 becomes equal to or lower than a predetermined value or the pressure on the discharge side exceeds the predetermined value, the operation of the compressor is stopped, so that the seizure of the compressor in the refrigeration cycle occurs. It is possible to prevent damage to the compressor drive device.

Next, the second invention of this application will be described.
FIG. 6 is a block diagram showing its configuration. The present invention is different from the first invention in that a timer circuit 12 for delaying the output by the pressure switch 3 is provided, and a malfunction due to the pulsation of the discharge pressure of the compressor 100 in the first invention is avoided with a simple configuration. In point. Since each means to which the same reference numeral as that of the invention 1 of the present invention is attached operates substantially the same as the means of the first invention, the description thereof will be omitted.

The timer circuit 12 has a function of delaying this signal for a predetermined time (for example, 10 to 30 seconds) and outputting it to the operation signal output means 10 when the pressure switch 3 is turned on. This timer circuit 12 can be configured as an independent means, and the software and CP
It can also be configured as a process executed by U6.

The operation will be described with reference to FIG. The processes of steps S1 to S6 are almost the same as those of the first aspect of the invention, so that the illustration is omitted and the description thereof is also omitted.

During the processing of steps S1 to S6, if the discharge pressure of the compressor 100 exceeds the set value and there is an interrupt due to the operation of the pressure switch 3, the control calculation function 63 of the CPU 6 executes the following processing. To do.

When the signal that the pressure switch 3 is turned off is received and an interrupt is made, the timer circuit 12 starts counting (S21).

It is judged whether or not the count value of the timer has reached a predetermined value (S22), and if it has not reached the predetermined value, step S
Return to 21 and continue counting.

When the current output of the pressure switch 3 is off, control calculation processing is executed (S24). That is, a signal for turning off the operation signal output means 10 is output and the state is maintained thereafter. In this state, when the reset signal input means 11 is turned on, the operation signal output means 10
The signal that turns on the output of is output.

The calculation result in step S24 is output to the operation signal output means 10 (S25), the operation of the compressor 100 to be controlled is stopped (S26), and the interrupt process is ended.

According to the present invention, the mechanical pressure switch 3
It is possible to prevent the compressor from being immediately stopped even if the erroneous operation occurs due to the pulsation of the discharge pressure.

In the above description, the operation signal of the mechanical pressure switch 3 is delayed and then the operation stop of the compressor is controlled. However, whether the pressure switch 3 operates to immediately stop the operation of the compressor or not. It is also possible to provide a means for self-maintaining this state after the operation is stopped through the above method so that the operation of the compressor is not restarted until a restart command is externally issued. According to the third invention in which the self-holding means is provided as described above, when the cause of the operation of the compressor is investigated, the cause is removed, and the operation is restarted, the operation is restarted before the cause of the compressor stop is removed. The inconvenience caused by restarting the operation of the cycle is not caused.

Next, the fourth invention of this application will be described with reference to FIGS. This invention differs from the first invention in that the discharge pressure on the discharge side of the compressor is controlled by the temperature sensor 3-2.
The point is to detect using. That is, the present invention utilizes the fact that the relationship between the temperature of the refrigerant and the pressure of the refrigerant is determined for each refrigerant in the refrigeration cycle, and uses the temperature switch that is extremely inexpensive as compared to the mechanical pressure switch to make the entire device. It is a reduction in the cost of. Further, since the temperature sensor used in the present invention has a response speed which is not as fast as that of the pressure switch, it has a function of averaging the pressure pulsation and has an effect that it is not necessary to delay the output.

The present invention is different from the first invention in that the temperature sensor 3-2 is used and its output is input to the A / D conversion means 4, and the CPU 6 uses a digital voltage (temperature)-. ROM with pressure value conversion function 64
71 differs in that it stores a digital voltage (pressure) -pressure value conversion table as well as a digital voltage (temperature) -pressure value conversion table.

The points different from the first aspect will be mainly described below. The temperature sensor 3-2 can use a temperature detecting means such as a thermistor whose resistance value changes with temperature. The output of the temperature sensor 3-2 is input to the A / D conversion means 4, is converted from an analog signal to a digital signal, and is then input to the CPU 6.

In the CPU 6, the digital voltage (temperature)-
The pressure value conversion function 64 obtains the discharge side pressure data using the digital voltage (temperature) -pressure value conversion table stored in the ROM 71.

The interrupt operation when the data of the temperature sensor 3-2 of the present invention is read will be described with reference to FIG. FIG. 10 shows only the interrupt operation when the reading operation of the temperature sensor 3-2 is performed, and the operations of steps S1 to S6 are the same as in the case of the first aspect of the invention, and therefore are omitted. Further, the interruption at the time of reading the data of the semiconductor pressure sensor 2 is the same as in the case of the first aspect of the invention, and therefore the description thereof is also omitted.

When the output of the temperature sensor 3-2 is read out, the A / D conversion means 4 performs a conversion process into a digital signal and the output voltage of the sensor is converted into a digital value (S31).

This output is converted to pressure value data by the digital voltage (temperature) -pressure value conversion function 64 in the CPU 6 (S32). As for this pressure data, since the responsiveness of the temperature sensor 31 is poor, the pulsation of the discharge pressure is averaged, the influence thereof is removed, and the average value of the discharge pressure is output.

Next, a control calculation process is executed using the obtained discharge pressure value (S33). That is, when the obtained discharge pressure value is larger than the OFF set value of the control condition, a signal for turning off the operation signal output means 10 is output, and on the other hand,
When it is smaller than the OFF set value of the control condition, the output of the operation signal output means 10 is held as it is.

The calculation result in step S33 is output to the operation signal output means 10 (S34), the operation of the compressor 100 to be controlled is stopped (S35), and the interrupt process is ended.

As described above, in the present invention, since the output of the temperature sensor is the average value of the pressure fluctuation, the discharge port of the compressor 100 can be provided without providing any special means for monitoring the pulsation of the discharge pressure. It is possible to prevent erroneous stoppage of the compressor 100 due to pulsation of the discharge pressure of 101.

Next, the fifth invention of the present invention will be described.
The present invention is to control the operation of the compressor 100 by using the differential pressure between the pressure value on the suction side and the pressure value on the discharge side of the compressor 100.

When evaluating the durability and reliability of the compressor during the refrigeration cycle, it is necessary to repeatedly turn the compressor on and off. In such a situation, after the compressor is turned off, if the pressure on the discharge side and the pressure on the suction side of the compressor are balanced, it takes time to restart the refrigeration cycle and the time required for evaluation. May increase. The present invention is an example of coping with such a problem. After the compressor is stopped, the minimum pressure difference between the pressure on the discharge side and the pressure on the suction side, for example, 3 Kgf / cm ² G is secured and restarted. By doing so, it is possible to easily restart the compressor.

The present invention will be described with reference to FIGS. 11 to 14. FIG. 11 is a block diagram showing the configuration of the pressure control device of the present invention, FIG. 12 is a diagram showing the functional configuration of the pressure control device of the present invention, and FIG. 13 shows the operation when there is an interrupt. FIG. 14 is a flowchart showing the operation of each pressure and compressor according to the present invention. The present invention will be described below with reference to the drawings.

The present invention is different from the first invention in that the means for detecting the discharge pressure on the discharge side of the compressor 100 is a semiconductor pressure sensor 3-3 similar to the pressure detection means on the suction side. The point is that the differential pressure between the outputs of the two pressure sensors is detected, and when the differential pressure decreases to a predetermined value, the operation of the compressor is restarted.

The output LP of the suction side pressure sensor 2 of the compressor 100 and the output HP of the discharge side pressure sensor 32 are input to the A / D conversion means 4, respectively converted to digital voltage values and output to the CPU 6. It Similar to the above-described invention, the CPU 6 converts the pressure value into the pressure value based on the voltage value-pressure value conversion table stored in the ROM 71 of the storage means 6. Each pressure value is compared with a set value stored in the ROM 71, and when the compressor is stopped, for example, when the output HP of the discharge side pressure sensor 3-3 exceeds the discharge pressure upper limit set value HS. Alternatively, when the output LP of the suction side pressure sensor 2 is below the suction pressure lower limit set value LS, the compressor 10 operates in the same manner as the above-described invention.
The operation of 0 is stopped (S46).

After stopping the compressor 100, the output LP of the suction side pressure sensor 2 and the output H of the discharge side pressure sensor 3-3.
P is monitored (S47), and the difference is a predetermined minimum pressure difference ΔP.
When the following occurs, the compressor 100 is restarted (S
48).

As described above, according to the present invention, when the difference between the output LP of the suction side pressure sensor 2 and the output HP of the discharge side pressure sensor 3-3 becomes a predetermined minimum pressure difference ΔP or less,
Since the compressor 100 is restarted, the time required for restarting the refrigeration cycle can be shortened, which is extremely effective, for example, when the compressor is repeatedly turned on and off.

[0074]

As described above, according to the present invention,
In the pressure control device of the refrigeration cycle, by using the semiconductor pressure sensor as the suction side pressure sensor of the compressor and the mechanical pressure switch as the discharge side pressure sensor, an inexpensive and reliable operation of the pressure control device can be obtained. .

Further, according to the present invention, by providing the timer circuit, it is possible to prevent unnecessary stoppage of the compressor due to malfunction due to pulsation of the pressure switch.

Further, according to the present invention, by making the pressure sensor on the discharge side an inexpensive temperature sensor, it is possible to make the entire apparatus inexpensive and utilize the slow response speed of the temperature sensor. It is possible to prevent unnecessary stoppage of the compressor due to malfunction due to pulsation of discharge pressure.

Further, according to the present invention, the compressor is restarted by detecting that the pressure difference between the suction side pressure and the discharge side pressure becomes equal to or less than a predetermined pressure difference, so that the compressor is restarted. It is possible to shorten the time required to restart the refrigeration cycle when repeatedly performing the on / off operation.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the configuration of a refrigeration cycle.

FIG. 2 is a block diagram showing the configuration of a pressure control device according to the present invention.

FIG. 3 is a functional configuration diagram of a pressure control device according to the present invention.

FIG. 4 is a sectional view showing the configuration of a mechanical pressure switch.

FIG. 5 is a flowchart illustrating the operation of the pressure control device according to the present invention.

FIG. 6 is a block diagram showing a configuration of a pressure control device according to a second invention.

FIG. 7 is a flowchart illustrating the operation of the pressure control device according to the second invention.

FIG. 8 is a block diagram showing a configuration of a pressure control device according to a third invention.

FIG. 9 is a functional configuration diagram of a pressure control device according to a third invention.

FIG. 10 is a flowchart for explaining the operation of the pressure control device according to the third invention.

FIG. 11 is a block diagram showing a configuration of a pressure control device according to a fourth invention.

FIG. 12 is a functional configuration diagram of a pressure control device according to a fourth invention.

FIG. 13 is a flowchart for explaining the operation of the pressure control device according to the fourth invention.

FIG. 14 is a characteristic diagram illustrating an operation of the pressure control device according to the fourth invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure control device with digital display means 2 Semiconductor pressure detection means 21 Pressure detection 22 Pressure-voltage conversion 3 Mechanical pressure switch 4 A / D conversion means 5 Input / output interface 6 Arithmetic processing means (CPU) 61 Digital voltage-pressure data conversion Function 62 Display data conversion function 63 Control calculation function 64 Digital voltage (temperature) -pressure data conversion function 65 Control calculation means 66 Pressure-output data conversion means 7 Storage means 71 ROM 72 RAM 73 EEPROM 8 Display means 9 Operation signal input means 10 Operation signal output means 11 Reset means 12 Timer circuit

Claims (7)

[Claims] 1. A pressure detecting means for detecting a suction side pressure of a compressor in a refrigeration cycle and a pressure detecting means for detecting a discharge side pressure, wherein when the suction side pressure is equal to or lower than a minimum pressure setting or the discharge is performed. In the pressure control device of the refrigeration cycle configured to stop the compressor when the side pressure becomes equal to or higher than the maximum pressure set value, the pressure detecting means for detecting the suction side pressure is a semiconductor pressure sensor, and the discharge side pressure is A pressure control device for a refrigeration cycle, wherein a pressure detecting means for detecting is a mechanical pressure switch. 2. A pressure detecting means for detecting a suction side pressure and a pressure detecting means for detecting a discharge side pressure of a compressor in a refrigerating cycle, wherein when the suction side pressure is equal to or lower than a minimum pressure setting or the discharge is performed. In the pressure control device of the refrigeration cycle configured to stop the compressor when the side pressure becomes equal to or higher than the maximum pressure set value, the pressure detecting means for detecting the suction side pressure is a semiconductor pressure sensor, and the discharge side pressure is A pressure control device for a refrigerating cycle, wherein the pressure detecting means for detecting is a mechanical pressure switch, and means for delaying the output of the mechanical pressure switch is provided. 3. A pressure detecting means for detecting a suction side pressure of a compressor in a refrigeration cycle and a pressure detecting means for detecting a discharge side pressure are provided, and when the suction side pressure is equal to or lower than a minimum pressure setting or the discharge is performed. In the pressure control device of the refrigeration cycle configured to stop the compressor when the side pressure becomes equal to or higher than the maximum pressure set value, the pressure detecting means for detecting the suction side pressure is a semiconductor pressure sensor, and the discharge side pressure is A pressure control device for a refrigerating cycle, wherein the pressure detecting means for detecting is a mechanical pressure switch, and means for retaining an output of the mechanical pressure switch in an accident is provided. 4. A pressure detecting means for detecting a suction side pressure and a pressure detecting means for detecting a discharge side pressure of a compressor in a refrigerating cycle, wherein when the suction side pressure is equal to or lower than a minimum pressure setting or the discharge is performed. In the pressure control device of the refrigeration cycle configured to stop the compressor when the side pressure becomes equal to or higher than the maximum pressure set value, the pressure detection means for detecting the suction side pressure is a semiconductor pressure sensor, and the discharge side pressure is A pressure control device for a refrigeration cycle, characterized in that the pressure detecting means for detecting is a temperature sensor. 5. The pressure control device for a refrigeration cycle according to claim 4, wherein the pressure is calculated based on the output of the temperature sensor. 6. A pressure detecting means for detecting a suction side pressure of a compressor in a refrigeration cycle and a pressure detecting means for detecting a discharge side pressure are provided, and when the suction side pressure is equal to or lower than a minimum pressure setting, or the discharge is performed. In a pressure control device for a refrigeration cycle, which is configured to stop the compressor when the side pressure becomes equal to or higher than the maximum pressure set value, the compression is performed when the differential pressure between both pressure detection means reaches a preset differential pressure value. A pressure control device for a refrigerating cycle, which is characterized by performing on-off control of a machine. 7. The pressure control device for a refrigerating cycle according to claim 6, wherein the pressure detecting means for detecting the suction side pressure and the pressure detecting means for detecting the discharge side pressure are semiconductor pressure sensors.