JP2012072920A - Refrigeration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency by controlling the number of revolutions of a blower for a condenser.SOLUTION: A refrigeration apparatus includes: a compressor 1; the condenser 2; and the blower 14 for the condenser having the controllable number of revolutions. The refrigeration apparatus further includes: a suction pressure sensor 101 which detects a suction pressure of the compressor; a delivery pressure sensor 102 which detects a delivery pressure of the compressor; and a control unit which controls the number of revolutions of the blower 14 for the condenser. The control unit memorizes the allowable range of a pressure ratio of the compressor in which the efficiency of the compressor is maximized, calculates the actual pressure ratio by using detection values of the delivery pressure sensor and the suction pressure sensor, and compares the calculated actual pressure ratio with the allowable range of pressure ratio of the compressor, in a state in which a refrigerating cycle of the refrigeration apparatus is stabilized, and controls the number of revolutions of the blower 14 for the condenser such that the actual pressure ratio falls into the allowable range when the calculated actual pressure ratio does not fall into the allowable range.

Description

  The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus that controls the rotational speed of a blower.

  As a conventional refrigeration apparatus that controls the rotational speed of a blower, as shown in Patent Document 1, the rotational speed of the blower is controlled so that the condensation temperature substantially matches the target value according to the evaporation temperature, and the air volume is adjusted. Refrigeration equipment is known.

JP 2002-147875 A

  In the above-mentioned Patent Document 1, consideration is given to preventing an increase in input due to an increase in discharge temperature due to an increase in height difference at a low outside air temperature and an increase in high pressure due to excessive air volume suppression. Not enough attention has been given to improving efficiency.

  Further, in another conventional refrigeration apparatus, the temperature of the liquid refrigerant discharged from the condenser is detected by a thermistor attached to the refrigerant pipe, and the output voltage of the condenser fan is detected by the fan controller according to the detected temperature. The rotational speed of the blower is controlled by changing. That is, the condenser blower is generally controlled independently according to the condensation temperature of the condenser, and no consideration is given to improving the efficiency of the refrigeration cycle.

  An object of the present invention is to obtain a refrigeration apparatus capable of improving efficiency by controlling the rotational speed of a condenser blower.

  In order to achieve the above object, the present invention detects a suction pressure of the compressor in a refrigeration apparatus comprising a compressor, a condenser, and a condenser blower capable of controlling the number of revolutions for circulating air through the condenser. A suction pressure sensor that detects the discharge pressure of the compressor, an allowable range of the pressure ratio of the compressor that maximizes the efficiency of the compressor, and stores the discharge pressure sensor and the The actual pressure ratio is calculated using the detected value of the suction pressure sensor, and the calculated actual pressure ratio is compared with the allowable range of the compressor pressure ratio in a state where the refrigeration cycle of the refrigeration apparatus is stable. And a control means for controlling the rotational speed of the condenser blower so that the actual pressure ratio falls within the allowable range when it is outside the allowable range.

  According to the present invention, by controlling the rotation speed of the condenser blower, the efficiency of the compressor is controlled so as to be improved, so that the efficiency of the refrigeration apparatus can be improved.

The refrigeration cycle block diagram which shows Example 1 of the freezing apparatus of this invention. The diagram explaining an example of rotation speed control of the air blower for condensers according to refrigerant | coolant temperature. The diagram explaining the other example of rotation speed control of the air blower for condensers according to refrigerant | coolant temperature. The diagram explaining the relationship between the pressure ratio in a compressor, and compressor efficiency. The control flowchart explaining an example of control of the freezing apparatus shown in FIG.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  Compressors vary in compressor efficiency depending on the operating pressure ratio, and each compressor has a unique pressure ratio that maximizes compressor efficiency. The pressure ratio inherent to the compressor with the highest efficiency is the same pressure ratio if the structure and dimensions of the compressor are the same (model is the same). Even if the capacities are different, the structure is similar and the capacity difference is 2 If the difference is about 30%, the pressure ratio is almost the same.

  Therefore, in this embodiment, the allowable range of the pressure ratio at which the efficiency of the mounted compressor is maximized is stored in the control device, and the suction side pressure (Ps) detected by the suction pressure sensor and The actual pressure ratio (Pd / Ps) during operation is calculated from the discharge side pressure value of the compressor detected by the discharge pressure sensor, and the actual pressure ratio is compared with the stored allowable range of the optimum pressure ratio. If it is outside the allowable range, the rotational speed of the condenser blower is controlled so that the actual pressure ratio of the compressor falls within the allowable range.

  That is, since the suction pressure is determined by the load of the low-pressure device connected to the refrigeration apparatus, it is necessary to change the discharge pressure (Pd) in order to change the actual pressure ratio so as to improve the efficiency of the compressor. Therefore, the discharge pressure (Pd) is changed by controlling the rotation speed of the condenser fan so that the efficiency of the compressor is further improved, and the compression ratio (Pd / Ps) is set to the target value (allowance for the optimum pressure ratio). Range).

Embodiment 1 of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a refrigeration cycle configuration diagram showing Embodiment 1 of the refrigeration apparatus of the present invention.
In FIG. 1, I is an air-cooled integrated refrigeration apparatus, and II is a low-pressure apparatus. These are connected by the pipe connection parts 15 and 16, and comprise the refrigerating cycle. In the air-cooled integrated refrigeration apparatus I, 1 (1a, 1b) is a scroll compressor, which may be a constant speed type driven by a commercial power source or a variable speed type driven by an inverter. In the example, 1a is constituted by a variable speed scroll compressor (inverter compressor) using an inverter, and 1b is constituted by a constant speed type scroll compressor (constant speed compressor).

  Reference numeral 2 denotes a condenser installed on the downstream side of the scroll compressor 1 (1a, 1b), and 3 denotes a supercooler constructed integrally with the condenser 2. A liquid receiver 5 is provided in the middle of the refrigerant pipe connecting the condenser 2 and the supercooler 3. Reference numeral 14 denotes a condenser blower for introducing outside air into the condenser 2 and the supercooler 3 for cooling.

  The high-temperature and high-pressure refrigerant gas discharged from the scroll compressor 1 enters the condenser 2 and is cooled and condensed by the outside air supplied by the condenser blower 14, and the condensed liquid refrigerant is stored in the receiver 5. Then, only the liquid refrigerant is guided to the supercooler 3 and further supercooled. The supercooled liquid refrigerant from the supercooler 3 passes through the dryer 9 and the sight glass 8, and then flows to the low-pressure apparatus II side.

  The low-pressure device II is composed of one or a plurality of evaporators 4, and each evaporator 4 is provided with an expansion valve 6 and an electromagnetic valve 7 on the upstream side thereof. Each low-pressure device such as a refrigerator in which each evaporator 4 is installed is provided with an internal temperature thermostat 301 that operates when the internal temperature becomes a predetermined temperature or lower, Each solenoid valve 7 is configured to open and close in accordance with the operation of its internal temperature thermostat 301.

  The liquid refrigerant supplied from the air-cooled integrated refrigeration apparatus I side to the low-pressure apparatus II side passes through the open electromagnetic valve 7, expands by the expansion valve 6, and enters the evaporator 4. The gas refrigerant evaporated in the evaporator 4 is returned again to the air-cooled integrated refrigeration apparatus I, constitutes a refrigeration cycle in which the gas refrigerant passes through the accumulator 13 and is sucked into the scroll compressor 1 again.

  The liquid refrigerant pipe between the dryer 9 and the sight glass 8 provided downstream from the supercooler 3 and the intermediate pressure chambers of the scroll compressors 1a and 1b are connected by liquid injection pipes 10 (10a and 10b). Has been. Each liquid injection pipe 10 is provided with a pressure reducing device 11 and an electromagnetic valve 12 each composed of an electronic expansion valve or a capillary tube for controlling the amount of liquid injection. By opening the electromagnetic valve 12, a part of the liquid refrigerant flowing through the liquid refrigerant pipe is injected into the intermediate pressure chambers of the scroll compressors 1a and 1b via the liquid injection pipe 10. Thereby, the temperature of the discharge gas discharged from the scroll compressor 1 is kept at a temperature equal to or lower than an allowable value.

  In the embodiment shown in FIG. 1, the example in which the liquid injection pipe 10 is connected to the liquid refrigerant pipe between the dryer 9 and the sight glass 8 is shown, but the connection point of the liquid injection pipe 10 is shown in FIG. The liquid refrigerant pipe is not limited to the above, as long as it is a liquid refrigerant pipe on the downstream side of the supercooler 3 and is connected to the liquid receiver 5 so that the liquid refrigerant in the liquid receiver 5 is injected into the scroll compressor 1. Also good. The decompression device 11 is not limited to an electronic expansion valve, and may be a decompression device using a capillary tube or an expansion valve. Further, the compressor is not limited to the scroll compressor 1, and may be a compressor of another type such as a rotary type.

The air cooling integrated refrigeration apparatus I is provided with a fan controller 201 that controls the condenser blower 14 and a control board (control device) 202 that controls the scroll compressor 1 and the like.
The fan controller 201 is configured to control the rotational speed of the blower 14 in accordance with the liquid refrigerant temperature (condensation temperature) detected by the liquid temperature thermistor 106 provided in the liquid receiver 5.

  Further, the control board 202 is connected with a suction pressure sensor 101, a discharge pressure sensor 102, a suction gas temperature thermistor 103, a discharge gas temperature thermistor 104, and an outside air temperature thermistor 105. Pressure values and thermistors from these sensors are connected. The control board 202 performs the rotational speed control of the inverter compressor 1a, the ON / OFF control of the constant speed compressor 1b, and the like based on the detected temperature.

  Note that the rotation speed control of the blower 14 by the fan controller 201 is not performed according to the temperature detected by the liquid temperature thermistor 106 described above, but instead of the blower determined according to the outside air temperature detected by the outside temperature thermistor 105. You may make it perform based on a characteristic.

Next, the rotation speed control of the condenser blower 14 will be described with reference to FIGS.
FIG. 2 is a diagram for explaining an example of the rotation speed control of the condenser blower according to the refrigerant temperature (voltage control chart with respect to the refrigerant temperature output to the blower by the fan controller to control the blower rotation speed). In the example, the rotational speed of the blower is changed by changing the voltage output to the blower 14. In this case, a DC (direct current) motor is used as a motor for driving the blower.

  That is, as shown in FIG. 2, the fan controller 201 determines and stores the output voltage ratio to the liquid refrigerant temperature (the rated output voltage is 100%) and is detected by the liquid temperature thermistor 106. Depending on the temperature of the liquid refrigerant, the output voltage to the blower 14 is determined, and if the liquid refrigerant temperature rises, the output voltage to the blower 14 is increased to increase the rotation speed, lower the condensation temperature to lower the condensation pressure, and accordingly Reduce compressor discharge pressure. Conversely, if the detected liquid refrigerant temperature falls, the output voltage of the blower 14 is lowered to lower the rotational speed, the condensation temperature (liquid refrigerant temperature) is raised to raise the condensation pressure, and the compressor discharge side pressure Raise.

  FIG. 3 is a diagram for explaining another example of the rotation speed control of the condenser blower according to the refrigerant temperature (frequency control chart with respect to the refrigerant temperature output to the blower by the fan controller to control the blower rotation speed). In this example, the rotational speed of the blower 14 is directly controlled according to the liquid refrigerant temperature. In this case, for example, the rotation speed of the induction motor may be controlled by an inverter. In the case of controlling the blower 14 as shown in FIG. 3, as in the case of FIG. 2, a target rotation speed ratio with respect to the liquid refrigerant temperature (with the rated target rotation speed set to 100%) is determined in the fan controller 201. The target rotational speed for the blower 14 is determined based on the temperature of the liquid refrigerant detected by the liquid temperature thermistor 106, and the rotational speed of the blower 14 is controlled in the same manner as shown in FIG.

  FIG. 4 is a diagram illustrating the relationship between the pressure ratio and the compressor efficiency in the compressor. That is, it is a diagram showing the characteristics of the compressor efficiency with respect to the ratio (pressure ratio) between the suction pressure and the discharge pressure of the scroll compressor 1. As shown in this figure, the efficiency of the compressor varies depending on the operating pressure ratio, and each compressor has a unique pressure ratio (optimum point A) that maximizes the compressor efficiency. . The pressure ratio inherent to the compressor with the highest efficiency is the same pressure ratio if the structure and dimensions of the compressor are the same (model is the same). Even if the capacity is different, the structure is similar and the capacity difference is small. The pressure ratio is almost the same. In the embodiment shown in FIG. 1, the inverter-driven scroll compressor 1a and the constant-speed scroll compressor 1b are identical or similar in structure and size, and have a unique pressure that maximizes the compressor efficiency. The ratio (optimum point A) is almost the same.

  The suction pressure to the compressor 1 is determined by the saturation pressure of the evaporation temperature determined on the low pressure device II side, and the discharge pressure is determined by the capacity of the condenser 2, the capacity of the blower 14, the outside air temperature, and the like. That is, the suction pressure is determined by the use application on the low-pressure device II side, but greatly changes due to the load fluctuation on the low-pressure device II side, and the discharge pressure of the compressor also varies accordingly. When the load of the low-pressure apparatus II is stabilized, the suction pressure is stabilized, and accordingly, the discharge pressure is also stabilized. However, since the blower 14 for controlling the discharge pressure is controlled by detecting only the liquid refrigerant temperature by the liquid temperature thermistor 106, for example, it is stable at points B and C in FIG. For this reason, the scroll compressors 1a and 1b are hardly operated at a place where the efficiency is high (a specific pressure ratio (optimum point A) at which the compressor efficiency is maximized).

  Therefore, in the present embodiment, the control board 202 stores in advance an allowable range (target pressure ratio) of the compressor pressure ratio that maximizes the compressor efficiency of the scroll compressor 1 (1a, 1b). . Then, the refrigeration cycle of the refrigeration apparatus is monitored while monitoring the operating state of the compressor using the detected values of the suction pressure sensor 101 that detects the suction pressure of the scroll compressors 1a and 1b and the discharge pressure sensor 102 that detects the discharge pressure. In a stable state, for example, when the actual pressure ratio during operation of the compressor (actual pressure ratio) is calculated and this actual pressure ratio does not change for a certain time (or when the discharge pressure or suction pressure does not change for a certain time, 14 (the output voltage to the DC motor) or the rotation speed may not change for a certain period of time), the refrigeration cycle is judged to be stable, and the actual pressure during operation of the compressor in that stable state The ratio is compared with an allowable range (target pressure ratio) of the pressure ratio of the compressor that maximizes the compressor efficiency stored in advance. As a result, for example, when the point indicated by B in FIG. 4 is stable, a signal is sent from the control board 202 to the fan controller 201 to increase the output voltage of the blower (increase the number of rotations) and discharge the compressor. The side pressure is decreased and the pressure ratio is controlled to be small so that it is in the region near the optimum point A in FIG. 4 (the allowable range of the pressure ratio of the compressor that maximizes the compressor efficiency).

  On the other hand, when it is stable at the point C in FIG. 4, the output voltage of the blower is lowered (the number of revolutions is lowered), the compressor discharge side pressure is raised, and the pressure ratio is increased. Thus, the region is in the vicinity of the optimum point A in FIG. In this way, in this embodiment, the actual pressure ratio during operation is calculated, and this actual pressure ratio becomes the optimum compression ratio (the allowable range of the pressure ratio that maximizes the compressor efficiency) of each compressor. The output voltage (the number of rotations) of the blower can be increased or decreased to improve the energy saving performance.

FIG. 5 is a control flowchart for explaining an example of the control of the refrigeration apparatus shown in FIG. 1, and the control procedure in the control board 202 shown in FIG.
First, when the operation of the refrigeration apparatus is started, the actual pressure values during operation (the suction pressure value Ps and the discharge pressure value Pd are read by the suction pressure sensor 101 and the discharge pressure sensor 102 (step S1).
Next, in step S2, an actual pressure ratio (Pd / Ps) during operation is calculated and stored from the read suction pressure value Ps and discharge pressure value Pd. In step S3, the change in the pressure ratio (Pd / Ps) is monitored. If the pressure ratio has changed, steps S1 to S3 are repeated again. When the change in the pressure ratio is lost, the process proceeds to step S4, and it is determined whether the elapsed time after the change in the pressure ratio is lost and becomes stable has passed a predetermined time. If the predetermined time has not elapsed, steps S1 to S4 are repeated. If the change in pressure ratio has ceased and a certain time has elapsed, it is determined that the refrigeration cycle has become stable, and the process proceeds to step S5. In step S5, the actual pressure ratio in the stable state is compared with a preliminarily stored compressor pressure ratio allowable range (target pressure ratio) that maximizes the compressor efficiency. As a result, if the actual pressure ratio is equal to the target pressure ratio (allowable range of pressure ratio at which efficiency is maximum), the rotation speed of the condenser blower 14 is maintained without being changed. (Step S6), the process returns to Step S1.

  As a result of the comparison in step S5, when the actual pressure ratio is different from the target pressure ratio, that is, when the actual pressure ratio is outside the allowable range of the pressure ratio at which the efficiency is maximum, the process proceeds to step S7. In step S7, if the actual pressure ratio is larger than the target pressure ratio (for example, in the region B in FIG. 4), the fan from the control board 202 is increased so as to increase the rotational speed of the condenser blower 14. A command is issued to the controller 201 (step S8). As a result, the fan controller 201 can increase the output voltage to the blower, increase the rotational speed, and decrease the condensing pressure, thereby reducing the compressor discharge side pressure (discharge pressure Pd). Therefore, the actual pressure ratio (Pd / Ps) can be reduced to approach the optimum point A shown in FIG. Thereafter, the process returns to step S1 and the same operation is repeated, whereby the actual pressure ratio can be made the target pressure ratio.

  When the actual pressure ratio is smaller than the target pressure ratio in step S7 (for example, in the region C in FIG. 4), the control board 202 is configured to reduce the rotational speed of the condenser blower 14. A command is issued to the fan controller 201 (step S9). As a result, the condensing pressure can be increased to increase the compressor discharge side pressure (discharge pressure Pd), and the actual pressure ratio (Pd / Ps) can be increased, so that the optimum point A shown in FIG. Thereafter, the process returns to step S1 and the same operation is repeated to make the actual pressure ratio the target pressure ratio.

  Note that the pressure on the compressor suction side may also change by increasing or decreasing the blower rotation speed in steps S8 and S9. In this case, the inverter is based on the detected value from the suction pressure sensor 101. By changing the rotational speed of the compressor 1a or controlling the number of operating compressors 1, the suction pressure Ps of the compressor can be controlled to an appropriate value according to the load of the low-pressure equipment.

  As described above, according to the present embodiment, the actual pressure ratio is calculated using the detection values of the discharge pressure sensor and the suction pressure sensor, and the calculated actual pressure is calculated while the refrigeration cycle of the refrigeration apparatus is stable. Control for controlling the rotation speed of the condenser fan so that the actual pressure ratio is within the allowable range when the ratio is outside the allowable range. Since the means (control board 202, fan controller 201, etc.) are provided, the condenser blower is controlled so that the compressor efficiency is optimized, and as a result, the efficiency of the refrigeration apparatus can be improved.

I: Air-cooled integrated refrigeration system, II: Low-pressure side equipment 1 (1a, 1b): Scroll compressor 2: Condenser 3: Subcooler 4: Evaporator 5: Receiver 6: Expansion valve 7: Solenoid valve 8 : Cytoglass 9: Dryer 10 (10a, 10b): Liquid injection piping 11: Pressure reducing device 12: Solenoid valve 13: Accumulator 14: Condenser blower 15, 16: Piping connection 101: Suction pressure sensor 102: Discharge pressure Sensor 103: Intake gas temperature thermistor 104: Discharge gas temperature thermistor 105: Outside air temperature thermistor 106: Liquid temperature thermistor 201: Fan controller (control means)
202: Control board (control device; control means)
301: Internal temperature thermostat.

Claims (10)

In a refrigeration apparatus comprising a compressor, a condenser, and a condenser blower capable of controlling the number of revolutions for circulating air through the condenser,
A suction pressure sensor for detecting the suction pressure of the compressor;
A discharge pressure sensor for detecting a discharge pressure of the compressor;
The allowable range of the pressure ratio of the compressor that maximizes the efficiency of the compressor is stored, and the actual pressure ratio is calculated using the detection values of the discharge pressure sensor and the suction pressure sensor, thereby freezing the refrigeration apparatus. In a state where the cycle is stable, the calculated actual pressure ratio is compared with the allowable range of the pressure ratio of the compressor, and if the actual pressure ratio is outside the allowable range, the actual pressure ratio is within the allowable range. And a control means for controlling the rotational speed of the condenser blower.   The fan controller according to claim 1, further comprising: a fan controller that controls a rotation speed of the condenser blower, wherein the fan controller is based on a characteristic of the blower determined according to a condensation temperature of the condenser or an outside air temperature. The refrigerating apparatus characterized by controlling the number of rotations.   3. The refrigeration apparatus according to claim 2, wherein the blower is driven by a DC motor, and the rotation speed of the blower is controlled by controlling an output voltage to the DC motor.   In any one of Claims 1-3, the said compressor is comprised by 1 or more units | sets, The at least 1 compressor is an inverter compressor which can control a drive frequency, and the detection value of the said suction pressure sensor is used. A refrigeration apparatus for controlling a drive frequency of the inverter compressor based on the control unit.   5. The refrigeration apparatus according to claim 1, wherein the compressor includes a plurality of compressors, and controls the number of operating compressors based on a detection value of the suction pressure sensor.   3. The refrigeration apparatus according to claim 2, further comprising: a liquid temperature thermistor that detects a temperature of the refrigerant condensed by the condenser; and an outside air temperature thermistor that detects an outside air temperature.   The refrigeration apparatus according to claim 6, further comprising a liquid receiver downstream of the condenser, wherein the liquid temperature thermistor is provided in the liquid receiver.   In any one of Claims 1-7, it is determined that the refrigeration cycle of the refrigeration apparatus is in a stable state when the actual pressure ratio has not changed for a certain time, and the actual pressure ratio and the pressure ratio of the compressor are A refrigeration apparatus that compares with an allowable range.   In Claim 3, when the output voltage to the DC motor does not change for a certain time, it is determined that the refrigeration cycle of the refrigeration apparatus is in a stable state, and the allowable range of the actual pressure ratio and the pressure ratio of the compressor A refrigeration apparatus characterized by comparing the above.   In any one of Claims 1-9, when the actual pressure ratio is larger as a result of comparing the calculated actual pressure ratio with the allowable range of the pressure ratio of the compressor, the rotation of the condenser fan When the actual pressure ratio is smaller, the rotational speed of the condenser blower is decreased. Further, when the actual pressure ratio is within the allowable range of the compressor pressure ratio, the condenser blower A refrigerating apparatus characterized by maintaining a rotational speed.

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